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 SOILS  OF  MOSCOW
AND  URBAN
ENVIRONMENT


Марина Строганова Алла Мягкова Татьяна Прокофьева Ирина Скворцова ПОЧВЫ МОСКВЫ и ЭКОЛОГИЯ ГОРОДА
Marina Stroganova Alla Myagkova Tatiana Prokofieva Irina Skvortsova SOILS OF MOSCOW AND URBAN ENVIRONMENT
List of Contributors Marina Stroganova is an associate professor at the department of soil geography, faculty of soil science, Moscow State University. She is the expert in the field of geography, cartography, and genesis of soils. Her field studies have covered Eastern and Western Siberia, the Far East, and the center of the European part of Russia. Among the most recent works are the Soil Map of the World (co-author, 1975, in Russian), textbook Soil Cover of Foreign Countries (1979, in Russian), monograph Soil and Biogeocenotic Studies in Forest Biogeocenoses (1989, in Russian). The last 10 years she studies the soils of cities in the center of Russia. She is the executive editor and co¬ author of the papers in the bode Soil, City, and Ecology (1997, in Russian). Alia Myagkova is a senior instructor at the department of soil science, faculty of soil science, Moscow State University. She is a specialist in the field of soil science, mineralogy, and geochemistry of soils. Starting in the 1960s, she have studied geochemical, mineralogical, and micromorphological properties of different types of soils. Her papers are devoted to the soils of the Tien- Shan, Caucasus, Polar Urals, Kola Peninsula, Karelia, Valdai, and Baltic Region. Soils of cities have gained her interest in the last 10 years with re¬ spect to general problems of urbanization. She is the co-author of papers in the book Soil, City, and Ecology (1997, in Russian). Irina Skvortsova is a senior researcher at the department of soil biology, faculty of soil science, Moscow State University. She possesses a profound exper¬ tise in the field of microbiological properties of natural and anthropogenic soils. The area of scientific interests is development of methods of indication of soil pollution by means of microbiological and plant tests. She partici¬ pated in writing of the monograph Microorganisms and Soil Conservation. She is the author of textbooks on identification of soil bacteria. She is also the author of papers in the bode Soil, City, and Ecology (1997, in Russian). Tatiana Prokofieva is a junior researcher at the department of soil science, faculty of soil science, Moscow' State University. Her expertise lies in the field of ecology of urban soils, including sealed soils. She is the co-author of papers in the book Soil, City, and Ecology (1997, in Russian) e-mail: marina@soil.msu.ru
CHAPTER 1 Global Problems of Urbanization The global environmental changes such as aridization, greenhouse effect, en¬ vironmental pollution, and degradation of soils and vegetation exert a consid¬ erable effect on the urbanized areas. The term urbanization involves city growth and development, growing proportion of urban population in a particular region, and acquisition by rural areas of industrial and social features of towns. Industrial, especially heavily populated, cities intensively grow since the middle of the 19th century. After cities had been involved in sophisticated production, they started to form spe¬ cialized industrial areas covering the area comparable to that under public houses. 1.1. Development of Urbanization In countries with a high fraction of urban population, urbanization is an acute problem. For example, in the Russian Federation, 100 million people, or 75% of the country's total population, live in towns and settlements, which occupy 0.65% of the area of the country. Of the total amount of towns in Russia in 1995, approximately two-thirds have acquired the status of the town in the 20th century and one-third has done it after the World War II (1945). In the mid-1990s, 43% of the w’orld's population, or 2.3 billion people, lived in urbanized areas in comparison with only 29% in 1950. If the growth of urban population follows the predicted tendency (by 2.5 times by the year 2005), then the proportion of urban population will exceed 50%. By the year
2025, more than three-fifths of the world's population (5.2 billion people) will live in the urban environment. Of this amount, 77% will account for devel¬ oping countries. As estimated, the urban population of developing countries will exceed that of developed countries by four times by the year 2025 (Fig. 1.1). Fig. 1.1. Daily increase of the categories of population over the period of 1950-2025 (data of the International Congress Habitat-H, Istambul, 1996). In Australia, New Zealand, Northern and Western Europe, the urban population exceeds 80%, whereas in Southern Europe, Eastern Europe, and the former Soviet Union it is 66, 63, and 66%, respectively. In Europe, the proportion of urban lands is the greatest in Belgium (28%), United Kingdom (12%), and Germany (11%). According to the Or¬ ganization for Economic Cooperation and Development, during the last 25 years, the area under construction has been increasing twice fast as the population. The world statistics does not give reliable data about areas under houses and industrial objects. According to the estimation of the Executive Committee of UNEP, urbanized lands comprise about 60 million ha or 0.46% of total land. As predicted, 3 .2 billion people will live in towns by the year 2000. The area of urbanized lands will exceed 100 million ha. Accelerated development of large cities increases the human impact both on the urban environment and on vast nearby rural areas. Typically, the area affected by the city- is 20 to 50 times greater than that of the city itself. Since suburbs are frequently contaminated with liquid, gaseous, and solid household and industrial wastes, cities are poorly provided with natural re¬ sources. Pollution is accompanied by the development of dangerous geody¬ namic processes (karst, subsidence, landslide, waterlogging, etc.). So, the sta¬ 250 ■ 1 00 Qurban (developed countries) ■ urban(developing countries) □ rural (developed countries ) Hrural {developing countries)
bility of lands decreases, while the role of abiotic factors and the ecological risk for all components of the environment (air, vegetation, water, and soils) increase (Osipov, 1994). The city is a model of the extremely unstable system incapable of self ¬ restoration and unable to withstand adverse environmental effects, including those induced by humans. The cost of maintenance of the stability in the ur¬ ban environment is very high and requires constant significant supply with material and energy. The ecological status of urban lands in megalopolises was analyzed by the example of Moscow. Large cities are characterized by rapid deterioration of the quality of all components of the environment and by high ecological risk because of accelerating urbanization and technogenic pressure on the en¬ vironment (About the Status..., 1993). The proportion of urbanized lands under cities and settlements and of lands under buildings, yards, streets, industrial enterprises, railway installa¬ tions, etc. significantly vary throughout republics of the former Soviet Union. According to the data of the Land fund of the Soviet Union, the urban lands on average occupy 1%. In more agriculturally developed republics of the former Soviet Union, the proportion of lands under settlements is greater, be¬ ing 8.95% in Ukraine (including 6.30% under rural settlements) and 8.29% (7.35%) in Moldova, respectively. In Russia, lands controlled by city and ru¬ ral administrations occupy 2.2% of the total country's area (Tabic 1.1). Table 1.1. The urban and settlement area in Russia Lands Percentage Lands under buildings, roads, streets, etc., 10.72 including those under buildings 5.07 Agricultural lands, 65.21 includmg arable lands 16.35 Forested area, includmg parks, squares, boulevards 9.85 Lands under trees and shrubs 3.00 Bogs 3.25 Water bodies 2.07 Disturbed lands 0.27 Other lands 5.63 Overall 100% Source: Stale (National) Report about the Status and Use of Land Resources in the Russian Federation in 1996.
1.2. Natural-Urban Ecosystems and Their Soils Research of urban soils is a new line in soil science. However, already 100 years ago V.V. Dokuchaev, the founder of modem soil science, paid attention to the necessity of studying soils of St. Petersburg and other cities of Russia. In 1890, he argued for “the detailed natural historical, physicogeographical, and agricultural study of St. Petersburg and its vicinities”. Dokuchaev devel¬ oped the ecologically comprehensive program of studies and recruited the most outstanding scientists to fulfill it. Under the leadership of Dokuchaev, the special commission worked on compiling the atlas of St. Petersburg, which included the following maps: hypsometric, geological (with mapping of groundwater and mineral re¬ sources), soil, zoological, botanical, agricultural, hygienic, and veterinary. “It is necessary to study genetic interrelationships between all diverse divisions and branches of natural science mentioned above, mostly concerning humans. ... The explanation of these relationships makes the essence of all truly scien¬ tific research and the highest, clear as a crystal, as beauty or as truth, pleas¬ ure of any science” (Dokuchaev, Selected works, vol. VII, 1953). The initi¬ ated work was stopped because of insufficient financing. Earlier the task to study soils of St. Petersburg has been set before the City Duma in 1875. The St. Petersburg Society of Naturalists (Section of Geology and Mineralogy') proposed to take a chance of extensive earthworks conducted by the City Government to establish horse railroads for the study of urban soils. So, the research of urban ecosystems and their soils may be regarded as old as the study of Russian chernozem. In 1982, Dolotov and Ponomareva already stressed the necessity of de¬ velopment of urban soil science—a direction in applied soil science. Presently, much research is devoted to fundamentals of the doctrine of urban ecosystems and to the role of soils in them. A number of works was published on urban ecology. In addition, the concept of modem “ecopolises”, maintenance of ecologically optimal conditions for human life, is developed by Kavtaradze (Zheveleva, Ignatyeva, and Kavtaradze, 1993). Thus, there is a widely known Vink's monograph Landscape Ecology and Land Use
(1983), in which special attention is paid to urbanized ecosystems. Recently, the collective volume Soil in the Urban Environment (1991) and the mono¬ graph of Craul Urban Soil in Landscape Design (1992) devoted to urban soils were published. The collective volume Ecogeochemistry of Urban Landscapes (1995) issued by the faculty of Geography (Lomonosov Moscow State University) was devoted to ecological and geochemical analysis of towns of Russia, Mongolia, and Poland. This book was the one to present geochemical princi¬ ples for ecological and geographical systematics of towns. They are based on quantitative and qualitative geochemical parameters, which characterize natu¬ ral and technogenic situation in cities. A number of towns has been studied using the same methodology that enabled the authors to develop guidelines for classifying towns and their components. Thus, N.S. Kasimov and A.I. PcrePman proposed two levels of systematics: (1) town as an integrated natural- tcchnogenic system and (2) individual urban landscapes within it. The geochemical systematics of towns (Table 1.2) proposed by Kasi¬ mov and Perel'man (1995) considers the intensity and character of techno¬ genic impact and the natural-technogenic geochemical situation (facilities for migration of pollutants). The urban geochemistry significantly depends on the location of town in the basin of atmospheric transfer, pollution peculiarities, and the self-cleaning capacity of the atmosphere. The type of cascade land¬ scape-geochemical system is also important. Table 1.2. Basic taxonomic units for the geochemical classification of towns (first level) according to Kasimov and Perel'man (1995) Taxonomic unit Recognition criteria Order Leading role of technogenic migration, artificial relief, and concen¬ tration of population Category The degree of technogenic impact on the population and urban envi¬ ronment Group Group of natural geochemical landscapes Type Type of natural geochemical landscape Family Peculiarities of air migration of technogenic products Class Class of water migration of technogenic products Genus Geochemical speciation of substratum
The geochemical systematics of landscapes within the city limits is based on the analysis of technogenic flows of pollutants, transformation of the natural environment, and resistance of natural-anthropogenic landscapes to pollution (Table 1.3). Table 1.3. Basic taxonomic units of the geochemical classification of ur¬ ban landscapes (second level) according to Kasimov and Perel'man (1995) Taxonomic unit Recognition criteria Order Occurrence in the functional zone and the type of pollution Division Peculiarities of deposition and emission of pollutants, geo¬ chemical speciation of emissions and wastes Family Severity and danger of pollution Group and type Peculiarities of nutrient cycling Class Class of water migration of technogenic products Genus Peculiarities of air and water migration, position in landscape- geochemical catenas Species Geochemical speciation of substratum Rapidly developing urbanization and expansion of areas under towns and settlements permanently modify the urban environment through the action of both internal and external factors. The process of urbanization produces an urban ccosystem. The urban ecosystem is an integrated natural-urban system composed of fragments of natural ecosystems surrounded by residential areas, industrial zones, roads, etc. The urban ecosystem is characterized by new types of hu¬ man-made systems resulted from degradation, destruction, and (or) substitu¬ tion of natural systems. The extent to which the functions of individual components of the urban environment are disturbed depends on the source, type, and intensity of hu¬ man impact and on the quality of the environment itself (Table 1.4). In urban ecosystems, the nutrient cycle is disturbed. Their biodiversity decreases as structural and functional characteristics worsen. The number of pathogenic microorganisms increases. So, the change in the quality of the ur¬ ban habitat deteriorates the living conditions for humans. Medical and demo¬ graphic parameters in towns become worse: disease incidence and the fre¬ quency of genetic diseases grow, new diseases appear, and the life expectancy decreases.
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The majority of urban areas, including Moscow, are subject to adverse processes that change ecological functions of soils. As esti¬ mated by ecologists, development of these processes will diminish the area under vegetation and soils, while the territory sealed with stone, asphalt, etc. will expand. In addition, worsening of soil hydrological properties (waterlogging and bogging), increase of ground-level pol¬ lution, and overuse of recreation facilities are expected. The other adverse ecological consequences are strong compaction within the rooting layer, contamination by wastes deposited on the soil surface, environmental pollution caused by regular and accidental emissions and global mass transfer, loss of soil organic matter, and changes in soil reaction. In addition, the diversity of the soil microflora decreases, while its struc¬ ture is transformed; soils are infected with pathogenic microorgan¬ isms (See Chapter 4). In modem soil science, there is an understanding of the necessity' of studying the surface cover of urban territories, while so far it was refered to as soil-ground, urban land, or merely land. There are two possible ap¬ proaches to this nontraditional object: (1) Urban soil is not a soil in Dokuchaev's pedological perception — it is a geological sediment. Therefore, it is the subject matter of engineering ge¬ ologists. At its best, urban soils can occur only in forest-parks and urban for¬ ests. These are the only sites in towns to which soil scientists may experience some interest. (2) Urban soil is a soil,.but its definition somewhat differs from the clas¬ sical view of soil as a natural historical body. We presume that the urban soil is a bio-mineral system that consists of solid, liquid, and gaseous phases and, obligatory, of living organisms. It per¬ forms certain ecological functions. Soils develop in town under the action of the same soil forming factors as natural soils. However, the leading role be¬ longs to the urban-anthropogenic factor.
• • • Urban soils are distinguished from natural soils mainly because: • of occurrence of fragments of constructional and household waste in the topsoil; • of changed acid-alkaline balance with a tendency for alkalization; • of high pollution with heavy metals and oil products; • of changed physicomechanical properties (lower water retention ca¬ pacity, strong compaction, stoniness, etc.); • of upward growth of the soil profile due to intensive aerial deposition; • they develop on filled, washed or mixed sediments, and cultural layers. The methodology of “pure” soil science, its field and analytical methods as well as its classification approaches can be definitely applied to urban soils. According to the second definition, this rather unique object deserves a greater attention of soil scientists and more thorough research. The additional argument to this is the great area occupied by urban soils.
CHAPTER 2 Basic Concepts of Urban Soils. Role of Soil in the Urban Environment What is an Urban Soil? • In a broad sense, an urban soil is any soil that is located in the urban environment * In a more restricted meaning, the urban soil is a soil directly affected by “the urban load”, and/or human-made soil in the town, with the human activity being simultaneously a trigger and a permanent regulator of the urban soil formation - urbopedogenesis 2.1. Urbanozem as a New Soil Type Urbanozems arc genetically individual soils that combine properties of natu¬ ral soils and some specific features.
We presume that a mature urban soil (or central image of the urban soil) is presented by a deep urbanozem on an ancient cultural layer. The profile starts with a deep dark-colored organic horizon — urbic (U) — growing up¬ wards owing to dust accumulation or anthropogenic input of matter. In humid areas, it lacks horizonation of the eluvial-illuvial type that is inherent to natural soils adjacent to towns. It is worth reminding that the con¬ cept of urbanogenesis and urban soils as its derivates is discussed in this book basing on the experience and data concerning the eastern European taiga. The majority of the profiles of urban soils are either turbated or de¬ stroyed, whereas the time required for the development of a mature profile is insufficient, since normal pedogenesis is incompatible with the life time of towns and cities (The “Eternal City”, Rome, may be among very rare excep¬ tions). Pedogenic processes, such as humus accumulation, gley formation, re¬ moval or redistribution of solid and liquid phase operate in urbanozems along with truncation, disturbance, and/or artificial input of matter and the effect of abundant artifacts (Stmganova et al., 1990, 1993, 1997; Burghardt, 1993. 1994, 1995). These pedogenic processes are more or less advanced in accor¬ dance with the age of the substrate, climate, and land use. The imprint of zonal pedogenetic features is thought to be obedient in all urban soils and their manifestations are rather evident in urbanozems on cultural layers or loose sediments. Nevertheless, the concept of urban soil applied by specialists in urban ecology now is more oriented to soil functioning in the environment than to morphology and traditional soil characteristics. Functioning presumes per¬ forming functions in the urban environment that are proper to natural soils and that complement with those originating from the specific behavior of ur¬ ban ecosystems. Urbanozems have been compared with the natural zonal soils — soddy- podzolic, or Podzoluvisols in the FAO system (Table 2.1). Summing up, it seems worth to emphasize that the most conspicuous properties of urbanozems are inclusions of wastes, compaction, alkaliniza- tion, accumulation of technogenic pollutants and growth of pathogenic mi¬ croorganisms.
Table 2.1. Common and specific properties of urbanozems and Podzolu- visols Common properties (1) Organomineral body (2) Importance of biological component (3) Organomineral compounds, humus (4) Pedogenic processes: lessivage, humus accumulation, gleying, redistribution of mineral compounds (5) Similarity of ecological functions: productive, sorptive, gaseous Specific properties of urbanozems Morphological properties (1) No genetic bonds between topsoil and subsoil (2) High horizontal and vertical variability (3) Artifacts, wastes, waste and other inclusions (4) Stratification; fabric diversity of strata (5) Cultural layers, paleosols as parent (underlying) rock Chemical properties and processes (1) Elevated alkalinity (2) High carbonate content (3) Predominance of humates (4) Accumulation of pollutants (5) Violation of nutrient cycling and dynamics Physical properties and processes (1) Abundant rock fragments (2) Compaction, structure degradation (3) Specific gaseous regime, low aeration (4) Stronger warming, weaker freezing (5) Contrasts in water regime Biological properties and processes (1) Low biodiversity, suppressed activity ofbiota, changes in its composition and structure (2) Low species diversity along with high biomass (3) Occurrence of specific pathogens
2.2. Classification of Urban Soils 2.2.1. Approaches, Definitions, Criteria, and Terminology An overview of the literature on urban soils has shown the high abundance of data on chemical and agrochemical properties for the urban soils in the Kuzbass region (Bachirova, 1970), Baltic states (Nicodemus et al., 1984), and Moscow (Lepneva et al., 1987, 1988, 1990; Obukhov et al., 1987, 1989, 1990 a, b; Nikiforova et al., 1995). This is in a strong contrast to the scarcity of information concerning their classification, functioning, and morphology (Gantimurov, 1966; Dolotov et al., 1982; Rokhmistrov et al., 1985; Short et al., 1986; Craul, 1992; Stroganova et al., 1993, 1997). Weakly studied re¬ mains the diagnostics of both disturbed and newly formed layers and soil ho¬ rizons, controversial is the system of their terminology and horizon designa¬ tions, which either derives of the knowledge of natural soils or follows formal substantive parameters. The importance of the problem and the growing in¬ terest of scientists forced them to insert translocated, turbated or artificial soils of towns into the already existing soil taxonomic systems. The definition of urban soils was coined by J.G. Bockheim in 1974, it was the following: “Soil material with a human-made non-agricultural layer deeper than 50 cm formed by mixing, filling or pollution of the land in urban and suburban territories'’. This definition was widely accepted and is used almost without any changes in many countries. • • • Following Bockheim (1974) and Bridges (1989), we define urban soils as soils having a human-made upper layer deeper than 50 cm resulting from mixing, filling, burial and/or pollution of town-produced material. The depth of 50 cm was chosen, since when thinner, the added material does not strongly affect the soil, which behaves like a natural body, except for drastically transformed soils, for example, those covered by a 15-cm-thick layer of asphalt or concrete. First classifications of urban soils are known since the 1980s, when they
were developed in Germany, Great Britain, the United States, and Poland for the purposes of soil survey in towns. These issues were especially successful in Germany, where a special Working Group on Urban Soils (Arbeitskreis StadtbodenlSoils of urban, trade, industrial, and mining sites) was organized in 1987 within the framework of the German Society of Soil Science — Deutsche Bodenkundliche Gesellschaft. In the last versions of the FAO Revised Legend for the Soil Map of the World (1989, 1994), there is a subunit of Urbic Anthrosols (within the An- throsols) comprising soils of towns and mines. Urbic Anthrosols have “more than 50 cm of accumulated wastes from mines, town waste, fills from urban development, etc." (Revised legend, 1989, p. 75). In the majority of national soil classifications, the soils of towns, even when considered, are dispersed over different taxonomic levels. Therefore, their nomenclature is far from being holistic. For example, in the German system (Blume, 1989) and in the last version of the New Russian Taxonomy (.Lebedeva et ai, 1997) the human-transformed or -made soils refer to the highest levels. In the American Soil Taxonomy (1975), they may be recog¬ nized as suborders in Entisols and Inceptisols, i.e., at the second level; al¬ though their separation from the natural soils is not clear enough. That is why the new order of Anthrosols was proposed in the mid-1980s, and a special commission (INCOMMANTH) elaborates a comprehensive svstematics of anthropogenically transformed soils and, as we hope, of urban soils in par¬ ticular. We presume that the taxonomic systems oriented at the natural soils are inapplicable to the urban ones, so special systems should be developed. Criteria for separating taxa in urban soil systematics comprise soil mor¬ phology; origin and evolution and the properties of the substrates. An applied approach was proposed by the Soil Survey of England and Wales (Clayden and Hollis, 1984). In it, a great soil group of man-made soils was subdivided into man-made humus soils (with a dark topsoil at least 40-cm thick) and disturbed soils (disturbed subsurface layer that extends below 40-cm depth) of open-cut mines G. Antonovic of Yugoslavia (1986) uses the name damaged soils to specify various types of contamination and/or physical disturbance; he em¬ phasized the difference between transformed natural soils and soils on human-
made substrates. The same approach was used by Hollis (1991), Agarkova and Stroganova (1991). According to Polish scientists, the properties of substrates are thought to be of primary importance. Konecka-Betley et al. (1985), and Czerwinski and Pracz (1991) subdivide soils at the highest level into mechanically trans¬ formed, loose sediments superimposing the natural soil, and chemically trans¬ formed soils. The character of transformations, origin and properties of sedi¬ ments are used at the next level. Of special interest for us is the legend to the map of Western Berlin; it is in the same time a classification of urban soils that has much in common with the approaches used for soil investigations in Moscow. At the highest level Blume (1989) identifies three categories of soils: soils of closed surfaces, transformed soils preserving natural features, and soils on filled and/or mixed substrate. For the natural soils, traditional soil names were applied, such as Pararendzina, Pararegosol, Parabraunerde, etc. Special artificial names were also introduced, such as Nekrosols for soils on cemeteries in the town. Arbeitskreis Stadtboden of the German Soil Science Society' published in 1989 the first draft of guidelines for urban soils mapping, where the term Urbic Anthrosols was substantiated for soils on human-made substrates. The soil evolution promoted by the natural environment comprises initial stages, when soils are comparable to syrozems; later on, they may evolve into Re- gosols, Rankers, Rendzina, and Pararendzina. Urban soils, that are more ad¬ vanced in their evolution should be categorized according to the rules applied for natural soils (Blume, 1989). Arbeitskreis Stadtboden suggests to combine the origin of substrate and stages of development for classifying urban and industrial soils (Table 2.2). Great importance is attached in the German system to human-produced substrates: truncated by scalping, mixing, impregnated by gases and liquids. They correspond to Meiktosols and Deposols — soils on mixed or deposited material, respectively. Meiktosols comprise Hortisols under gardens in towns, Nekrosols, in cemeteries and church yards. Deposols are formed by addition of material more than 40-cm deep; if this material overlays the natural sub¬ strate, Allosols are formed, if the substrate is technological, these are Techno- sols, if the lower substrate is mixed, soils are qualified as Phyrosols. Soils with strong reductive features confined to organic garbage are termed Re-
ductosols, oil-impregnated soils near the gasoline stations are recognized as Intrusols. Individual categories are formed by Denusols — denuded, or trun¬ cated soils — and Lithosols that comprise soils with high content of rock fragments along with soils under asphalt or stony pavement. Table 2.2. Class: Urbic Anthrosols 1. Meiktosols (mixed substrates) Without material input Treposols (deep-ploughing) Rigosols (mixing > 30 cm) With humus input (Ah > 40 cm) Hortisols (garden soil) Nekrosols (church yard soil) 2. Deposols (deposited material >80 cm) Allosols (natural substrates). Phyrosols (mixture of natural and technological substrates). Technosols (technological sub¬ strates) Allosyrosem*; Alloregosol**; Allorendzina*** Phyrosyrosem*; Phyroregosol**; Phyrorendzina***. Technosyrosem*; Technoregosol**; Technorendzina * * *. 3. Reductosols (reduced by methane) No further subdivision 4. Denusols (scalped to depth > 40 cm) No further subdivision 5. Intrusols (recently penetrated by ground¬ water, dust, gases, and organic liquids) No further subdivision Source: Arbeitskreis Stadlboden. 1989; Schraps, 1989; cited from Burghardt, 1994. * development of Ai-C-Profile (Syrozems); ** development of Ah-C-profile, without carbonates (Regosols); *** development of Ah-C-profile, with carbonates (Calcaric Regosols). Note: Allosols, Allosyrosem, Alloregosol, and Allorendzina evolve to Braunerde (Cambisols) and are classified like soils of natural origin. Basing on the analysis of these and some other sources and following the ideology' of the New Russian Taxonomy, the authors proposed their own systematics of urban soils for substrates occurring in the European taiga .
2.2.2. Urbic Diagnostic Horizon We think reasonable to specify the urbic (urbs, urbanus—town, city) diag¬ nostic horizon as an individual horizon basing on its individual features and taking into account the pedogenetic agents responsible for its properties, as well as processes inherent to this horizon. Urbic horizon is regarded as a di¬ agnostic one for the majority of urban soils and as a criterion to discriminate them with the natural soils. It is worth reminding that the concept of diagnos¬ tic horizons is widely applied now in the New Taxonomic System in Russia. The urbic horizon is being formed in towns and cities during centuries, or it may be “constructed” in a few days in the course of landscape design¬ ing, forming lawns or gardens. Once being made, it gradually adjusts to the urban soil body, presumably, this process is quicker than pedogenesis under natural environment. Such “adjustment”, or tending to equilibrium with the soil body, may be never reached: urbic horizon does not display any genetic bonds with the underlying material. We consider this discrepancy to be one of the indications to recognize and classify an urban soil. • • • Properties of urbic horizon in different soils of towns vary in a wide range, and this is also its diagnostic feature. High variability is recognized for texture, bulk density, some chemical properties, and abundance of artifacts. The latter feature is expedient; artifacts comprise municipal wastes, remnants of pottery, wire, plastic bags and the like. The urbic horizon is always a topsoil (unless buried), mixed; although it is not necessarily heterogeneous. It is made in most cases by accumulation of loose, partly oiganic matter over a buried soil (paleosol), or its remnants, or any other ground (Fig. 2.1). The contribution of eolian processes — urban dust transfer to the pool of fine earth in urbic horizon is not negligible. (Chapter 4). Texture and consistence strongly vary' in accordance with the contribution of different materials, although loamy sands or sandy loams pre¬ dominate. Measurements of the bulk density in Moscow soils showed its fluctuations within 1.1 and 1.6 g/cm3. The structure of the urbic horizon is mostly weak; aggregates are rather unstable and dominated by clods, angular blocks or crumbs. Crumby or
granular aggregates occur locally near the sleeping chambers or channels of earthworms. Most of urbic ho¬ rizons are dark in color: according to Munsell soil colour charts, the value should be four or less. The upper part of the urbic horizon is en¬ riched in humus; the bulk of it contains more humus than the back¬ ground soils. The com¬ position of humus may be termed as relatively humate: the proportion of humic acids and of their second fraction (bound with Ca) is more elevated than it should be under the existing climatic conditions. Rather elevated are the values of nonhydrolyzable residue, testi¬ fying to rather unfavorable conditions of oiganic remains transformation into humus substances. The urbic horizons are mostly base-saturated and have a neutral to moderately alkaline pH, which is explained by the addition of cement or lime¬ stone dust, and by the neutral to weakly alkaline pH of atmospheric fallout: industrial and/or town dust and “alkaline” rains'. Effervescence with hydro¬ chloric acid has been registered for some urbic horizons. Micromorphological data confirm the major specific features of the ho¬ rizon. Thus, the hindered transformation of oiganic residues is recognized in thin sections by the frequent occurrence of weakly decomposed plant tissues, similar to organic skeletal material of podzolic soil litter (S. Sedov, personal Fig. 2.1. Ingredients of the urbic horizon substrate. 1 Along with '“acid rams ', very popular among ecologists, large industrial centers are known lor their elevated pH fallout owing to industrial emissions (Kasimov et al., 1995).
communication). Fine organic matter is flaky, brownish in colour. Calcite grains are common in the majority of uibic horizons. These are mostly primary, rock-inherited carbonates; however, indices of carbonates re- distriburion — coatings (calcitans) and plasma impregnations were identified. The S-matrix is often heterogeneous—composed of microfragments, or inclusions, among which remnants of initial soil horizons are frequent, such as ВТ horizon “outliers”, or those of the Al horizon of a young humus- accumulative soil formed on a sandy embankment. Thin section studies of urbic horizons are not yet numerous. Neverthe¬ less, three main features are thought to be diagnostic for the urbic horizon: weak oiganic matter decomposition, heterogeneity, and presence of active carbonates. Along with these, proper to “the central image” of urbic horizon, we have encountered such pedofeatures as iron-manganic nodules, vivianite neoformations and bleached skeletal grains in oiganic matter-enriched micro¬ zones. This assemblage is indicative of current gley and eluviation processes. Urbic horizon should be at least 5-cm thick. It is made by land trans¬ porting and may comprise the cultural layer with its artifacts (Fig. 2.1). Processes inherent to the urbic horizon are dominated by the natural ones. Among the main processes operating in the urbic horizon, the following should be enumerated: humus accumulation, structuring (comprising biogenic reworking), biopedoturbation, weak lessivage, gley + iron segregation, and mobilization of carbonates. There are two more processes, which may be re¬ ferred to human-induced: pollution by heavy metals and polycvclic aromatic hydrocarbons, the occurrence of pathogenic microoiganisms, and ephemeral discontinuous salinization. We have tried to look for analogues of the urbic diagnostic horizon in other taxonomic systems. The diagnostic horizons were not identified in the former Russian sys¬ tem (Classification and Diagnostics of Soils of the USSR. 1977). In the FAO list of diagnostic horizons, urbic horizon is absent w hereas the list of soils includes Urbic Anthrosols. which are qualified as soils of cer¬ tain sites (1989).
The WRB system — the FAO derivative — along with diagnostic hori¬ zons, comprises anthropogenic soil material for towns, oil spills, landfills, and mines (1994). Anthrosols were also recognized there, although the Urbic Anthrosols unit was excluded. Only strongly transformed agricultural soils are ingredients of the Anthrosol group. Soil Taxonomy (1975) has its anthropic horizon which covers at least the major part of the proposed concept of the urbic horizon The modem literature does not contain examples of the diagnostics, de¬ scription, and notation of soil horizons with special respect to urban soils. However, recently, A Field Manual on Description of Soils in Urban, In¬ dustrial, and Mining Areas was published in Germany (Empfehlungen des Arbeitskreises Stadtboden..., 1997). It contains a list of major and minor symbols of horizons. The major indices of horizons (capital letters) designate natural horizons grouped in subaquatic, oiganic, and mineral. Minor indices of horizons (small letters) designate “geogenic, anthropogenic, and pedogenic properties”. Thus, the category of anthropogenic and geogenic horizon sym¬ bols reflects the content of carbonates, marlstones. and humus, relict and al¬ luvial features, impregnation with oil, types of natural and artificial substrates redeposited by humans, seaside deposits, etc. The category of pedogenic horizons symbols indicates lessivage, ferrali- tization, degree of oxidation, clay depletion, presence of concretions, biogenic mixing, secondary salinization, etc. However, this system (ideology) does not recognize peculiarities of urban soils by themselves. Furthermore, anthropo¬ genic and landscape (geogenic) properties are separated from pedogenic ones. We proposed the other system of horizon indices that was tested and re¬ fined during soil surveys in Moscow. We think it is easy to use and embraces reflects the main properties of urban soils. The notation categories are in good agreement with the principles of horizon notation used by the New' Russian Soil Classification System. The main elements of horizon notation in urban soils are shown below'. The urbic horizon is designated as U (always capital letter), one soil profile may have several urbic horizons. This index is followed by an Arabian numeral — Ul, U2, etc. — similarly to that as it is used for many natural
diagnostic horizons (BT1, BT2; Al, A2). For indication of processes (features) superimposing the major process, the following letters are used: Major indices of urbic horizons Ud—soddy urbic horizon; Uh—humus-enriched urbic horizon; Uih—illuvial-humus urbic horizon. Humus illuviation is identified along root channels and animal passages. Ug—gley urbic horizon; Uca—calcareous urbic horizon; Upt—petroleum-enriched urbic horizon. Minor indices are used for weakly manifested properties of urbic horizons and when urbic features superimpose on “natural” genetic horizons: Au—humus accumulation with some urbic features; Elu—eluviation with some urbic features. Indices of other layers, which can be specified: Cu—parent rock that at the same time is a part of the cultural layer; Du—underlying rock that may be presented by the cultural layer; L—stony layer, e.g., remnants of basements and old brick walls; L—artificial barrier like asphalt or concrete layer within the soil. The abundance of inclusions of construction, industrial, and municipal wastes as percentage of the total volume of the layer or horizon are indicated by the letter a (anthropogenic) (Draft for Soil Horizons Notation, 1982). Thus, the following grades are recognized: al — few; a2 — <25%; a3 — 25-50%, a4 — >50%. Each soil has its own set of horizons, for example: weakly disturbed soddy-urbo-podzolic soil: О—Uld—U2hal—ELB—В—С; medium thick urbanozem consisting by 25% of artifacts and underlain by a concrete plate: Ulha2—U2a2—U3al-—U4al—3—L. Thus, the small letters are practically the same as those used for similar purposes for designation of natural soils. Among possible exceptions is a mixed urbic horizon composed of fragments (morphons) of natural horizons and cultural layer, waste, garbage, etc.
2.2.3. Urban Soils within the Framework of the New Russian Taxonomic System The urban soils were not included into the former official Russian system {Classification and Diagnostics of Soils of the USSR, 1977). However, the new system proposed by Dokuchaev Soil Institute in Moscow (Lebedeva, Tonkono- gov, and Shishov, 1993) that is underway now, provides high-level taxa for an- thropogenically transformed soils and for soil-like bodies. Taking this approach for the basis and assimilating the experience of colleagues from other countries concerning urban soils systematics properly, we made an attempt to insert soils of towns that we have studied in Central Russia into die New Russian Taxonomic System We consider this attempt to be the “first approximation”, partially be¬ cause of the feet that our urban soils are not yet full ingredients of the system; the system itself is flexible and the place of different urban soils may be shifted. In any case, we have to cope with the new national basic system, and further studies are expected to make contributions to the problem. In accordance with the principles of the New Russian Taxonomic System, soils of towns are classified by their profile as universal and comprehensive crite¬ rion, which is supported by recognition of properties of parent materials. Soils of towns comprise natural (undisturbed) and human-transformed soils, which are further subdivided into surface-transformed (urbo-soils), and strongly transformed (urbanozems and chernozems). There are also human- made, or technogenic, soil-like bodies—urbotechnozems (Table 2.3). Major mor¬ phological features of these groups of urban soils are given on Fig. 3.9. The natu¬ ral undisturbed soils preserve the normal sequence of horizons and occur under urban forests and forest-paiks located within the town. They have some features caused by the effect of town, which may be mainly disclosed by chemical analy¬ ses, e.g. elevated concentrations of heavy metals, higher pH than in similar soils outside the town. They may also contain artifacts that do not exert any influence on the composition of their profiles. The surface-transformed soils comprise soils with transformations not penetrating deeper than 50 cm. Hence, their profile is composed of two different sequences of horizons: the topsoil is presented by urbic horizon less than 50-cm thick; the subsoil is undisturbed and preserves the initial set of horizons. The nomenclature of surface-transformed soils is in complete accor¬ dance with the principles used in the new system for such “semi-natural” soils
changed by fanning, erosion, mining etc. It is composed of the prefix indi¬ cating the type of disturbance: agro-, abra- (abraded = eroded), chemo- (changes in chemical poperties), respectively; in our case we have urbo-. The second member of the name indicates the original soil, so we have urbo- podzolic, urbo-alluvial, urbo-peaty soils in Moscow. ТаЫе 2.3. Categories of soils occurring in towns Soils Soil-like bodies Natural Human-transformed Human-made Surface transformed Strongly transformed physically chemically natural urbosoil urbanozem chernozem urboteduwaan Podzolic, alluvial, peaty urbo-podzolic, uibo-podzolic-gley, uibo-alluvial urbanozem agrouibanozem ekranozem nekrozem industrizem intruzem replantozem constructozem Strongly transformed soils in the New Russian Taxonomic System are classified separately: special high-level units are provided for them, which are compatible with such units as soils with textural profile, alluvial soils, Al-Fe- humus soils, etc. These units (orders — second level) comprise agrozems, abrazems (abraded, or eroded soils), chernozems (chemically intoxicated soils), stratozems (stratified soils with non-fluvial accumulation of material, they may originate by both natural and artificial ways). The majority of strongly-transformed soil orders are still weakly studied, and they cannot be regarded specific for the urban environment. Urbanozems Strongly transformed soils in towns are subdivided in accordance with domi¬ nating conspicuous changes in their properties: either physical (mechanical), or chemical. Soils with predominant strong physical transformations are pre¬ sented typically by urban soils — sensu stricto urbanozems. Their urbic ho¬ rizon is deeper than 50 cm; they occur on cultural layer, mixed or filled rocks, which are also more than 50-cm thick. Soil profiles comprise a set of U hori¬ zons (Ul, U2. . .), frequendy with admixture of town waste and followed by
impermeable layers (asphalt, concrete plates, pipelines); no other genetic ho¬ rizons may be recognized to the depth of 50 cm and even lower. Urbanozems comprise some speicfic soils, which are termed in accor¬ dance with the agent of their mechanical pedoturbation: culturozem, nekro- zem, and ekranozem. Culturozems (agrourbanozems) are urban soils of city gardens, old kitchen gardens, and botanical gardens. Culturozems have a thick humus ho¬ rizon, mucky-peaty-compost layers or lenses, the total depth exceeding 50 cm. This horizon is underlain by the original illuvial subsoil (argic horizon), cultural layer, or any other sediments. Culturozems may be also named agrourbanozems, if following the rules of the New Taxonomic System. Nekrozems are soils of cemeteries in towns; the depth of turbation is above two meters. Ekranozems is a preliminary name for sealed soils under asphalt or other impermeable layers as well as under stony pavements; the term origi¬ nated from the Russian word “ekran”, i.e., “screen” or “barrier”, and empha¬ sizes on the isolation of the soil body. Chernozems Properties of chernozems — chemically altered soils — are strongly changed by pollutants, penetrating the soil body both in a gaseous and liquid forms. They comprise industrizems and intruzems. Industrizems. Soils of industrial and municipal areas, severely polluted by heavy metals and/or other toxicants that change the CEC, almost eliminate the biodiversity, and even approximate them to abiotic bodies. Nevertheless, the initial soil profile (natural soils, or any of urbanozems) is recognized as basically unchanged. Soils are compact, lack structure, contain toxic non-soil inclusion—more than 20% by volume. The name is conventional and may be substituted by “pollutozem” Intruzems. Soils impregnated by organic oil and benzene liquids near refilling stations, or any oil-producing or transporting systems. As in the pre¬ vious case, the initial profile may be preserved; the leakage of oil products makes it “greasy” and smelling. The alternative names may be “neftezem” (neft = oil), or “urbochemozem” if the topsoil meets the criteria of urbic hori¬ zon. This means that polluted (impregnated) might be a natural soil, an urbo- soil, urbanozem or industrizem.
Urbotechnozems Along with these soils, soil-like human-made superficial bodies occur in towns — urbotechnozems. These are artificial soils — replantozem and constructozem — made by application to parent rock of fertile soil material, peat and/or composts. The soils are intergrades between “technozems”, which are non-soils and any urban soils; formerly they were termed “soil-grounds” (Zemlyanitskiy, 1962) in towns. Replantozems (the term was proposed for agricultural soils) comprise a thin humus horizon or a layer of peat-compost mixture placed over the surface of the rock in the course of rehabilitation pro¬ cedures. Soils are common in industrial areas on newly made lawns or in “sleeping blocks”. Construcrozem are completely artificial soils fully made from different materials with a humus-enriched layer on the top. Such soils are more hypo¬ thetical than real and may serve as an objective of further research. The criteria to further subdivision of human-affected soils are based on soil properties indicating a weak development of either natural or human- induced processes. The set of adjectives for the former processes and features is the following: soddy, carbonate, gleyic, leached, peaty, skeletal, primitive. Soils and soil-like bodies with artificial processes and properties are described by the following terms: ekranic, chemically-polluted (composition of pollut¬ ants is worth mentioning), low-biotic, oil-impregnated (intrusic), scalped (abraded). We presume that parent material is of primary importance for classify¬ ing the urban soils. This aspect was traditionally regarded in the Russian soil systematics at the level of genus. Parent rocks are specified in terms of origin, chemical composition, and texture. Three major groups of parent rocks are the most common for urban soils: mixed (in situ), filled (transported), and dredged. The degree of disturbancc/prcscrvation of the solum ranges from weak (in soils disturbed to the depth of 10-25 cm) to the strongly disturbed ones (up to 25-50 cm); buried soils with partially or completely preserved profile are also identified. Following traditional approaches, the extent of development of any phe¬ nomena in soil, or abundance of anv other qualitative parameter is referred to
as the species level. Thus, there are several soil properties characterized at the species level: • profile thickness: weakly developed soils <10 cm; shallow soils 10-50 cm, moderately deep soils 50-100 cm; deep soils >100 cm. • type of artifacts: (construction and municipal waste, industrial waste), or peat-mucky inclusions and fragments of soil horizons. • abundance of artifacts, percentage of the soil volume; few <25; com¬ mon 25-50; many >50. • depth of humus-enriched layer: shallow <15 cm; moderate 15-30 cm; deep >30 cm. • manifestations of gley: superficially and deeply gleyed. Examples of full names of soils are rather long and intricate: urbo- podzolic deeply gleyed lead-polluted loamy soil on loamy till; shallow car¬ bonate low-humus stony loamy sandy replantozem on construction waste, etc. Thus, in a large town, soils occur both on the land surface as natural soils, urbo-soils (seminatural soils), urbanozems (strongly human- transformed soils) and urbotechnozems (soils-sediments) and at a certain depth as soils or paleosols. The last are urban soils within the cultural layer or natural soils that existed before humans have inhabited this area. Along with these diverse bodies, there are plots with garbage and other town waste domi¬ nated by mineral rock or weakly humus-enriched thin upper layers. 2.2.4. Some Aspects of Urban Soils Evolution The driving forces of the evolution and transformation of urban soils are the following. • functional properties and land-use pattern: residential area, industrial zone, recreation or natural zones; • kinds of substrates, their physical and chemical features: the cultural layer, land fills, mixed and dredged sediments, and remnants of natural soils; • age: large time intervals starting with the Middle Ages (or even earlier) when cloisters, palaces, etc. had been established on deep cultural layer or series of artificial and natural paleosols and lasting until the present time when new "sleeping quarters” were constructed either over former arable or forested lands or over garbage and municipal
wastes disposal sites. The formation and evolution of urban soils comprises: • changes of natural soils: zonal soil—^weakly or strongly disturbed zonal soils (urbo-soil)—Hirbanozem. • development of soils on sediments: sediment (mineral sub¬ strate)—>organosediment (fresh peat-compost mixture on a sediment, urbotechnozem)->urbanozem. • development of soils on cultural layer: cultural layer—>urbanozem Formation of urban soils in time, or evolution trends, may be the fol¬ lowing: • transformations of quasi-natural and urbo-soils—natural evolution in town gardens or forests slighdy affected by urbogenesis; • development of soils on mineral sediments—zero-moment for pe¬ dogenesis in recently constructed residential areas; • formation of soils on organomineral mixed, filled or dredged sediments in suburbs and middle part of towns (“soil on sediment”) from zero- moment to nowadays; • changes in properties of soils on cultural layer (dated surfaces in the downtown). A set of specific urban processes is superimposing over the evolution models enumerated: chemical contamination, alkalinization, calcification, and salinization. 2.3. Ecological Functions of Urban Soils The principal postulate of soil science is that pedogenic processes develop when there are energy input to soil, matter and energy' exchange between soil and other natural bodies (atmosphere, substratum and living matter), and their transformation and transfer (Rode, 1971). As our research showed, soils of urban ecosystems have new components and matter-energy links com¬ pared to natural soils. Therefore, some additions and refinements should be done when regarding urban soils. There are the following processes of matter and energy exchange be¬ tween soil and other natural bodies:
(1) Gas exchange in the system of atmosphere (e.g., industrial gas emis¬ sions) — soil — plant (root) — substratum (e.g., leakage from pipe¬ lines); (2) Exchange between liquid and vapor water in the system of atmos¬ phere (e.g., industrial gas emissions) — soil — plant — substratum (e.g., leakage from pipelines); (3) Heat exchange in the system atmosphere (e.g., houses, thermal power stations, etc.) — soil — plant — substratum (e.g., leakage from pipelines); (4) Dust exchange in the system atmosphere — soil — plant — sub¬ stratum — construction and road surfacing; (5) Removal of organic matter synthesized by higher plants to soil (absence of forest litter and cutting of lawns); (6) Synthesis and decomposition of organic compounds (e.g., humification). The following processes occurring between urban soil (except the soils of natural complex) and other natural bodies are absent or negligible: (1) Bilateral exchange of ash elements and nitrogen in the system soil — higher plant (slow biological cycling). The exchange between soil and plants becomes one-sided, since leaf residues and dry branches and trees are removed, lawn grasses are cut; (2) The transformation of autrophic (detrital) residues by soil biota, when the quantity' of plant litter is small. We think that basic functions of soils in urban ecosystems are similar to those in natural soils (Dobrovol'skiy and Nikitin, 1990). The soils are the medium, where biogeochemical matter cycling and biochemical transforma¬ tion of filled layers occur and surface water is converted to groundwater. They also serve as a nutritive substratum for plants, seed bank, regulator of gas exchange, etc. Ecological functions performed by soils in towns are variable. Their main properties are fertility (soil suitability for plant growth) and capacity of absorption to prevent penetration of pollutants to soil and groundwater and, with dust, into urban air. The role of soil in towns is significant and diverse (Fig. 2.2). Soil makes up the framework of the environment, it alters the chemical composition of precipitation and groundwater; it is the universal biological sorbent, supplier and regulator of C02. Ck and N2 in the atmosphere.
Fig. 2.2. Soil functions in the urban ecosystem. In large cities — megalopolises — especially in highly industrialized ones, urban soils badly perform their ecological functions (Table 2.4). Degra¬ dation or weakening of ecological functions is especially severe in cities with strong chemical industry and in those located in northern regions. Soil in the city is a strong sorptive barrier for gases, including those emitted by motor transport, thermal power stations, plants, etc. It also regu¬ lates the gas composition of the atmosphere by emitting or sorbing the gases (methane, ammonia, carbon dioxide, etc.).
Table 2.4. Transformation and degradation of environmental functions of urban soils Natural soil Urban soil Soil-water Conversion of sewage wa¬ ter into groundwater and its cleaning. Sorptive barrier protecting rivers and lakes from pol¬ lution. Alteration of the chemical composition of water Water passes soil by asphalt or through the surface of compacted soil and enters rivers. On its way through soil, water is contaminated with heavy metals and toxic compounds, so its composition when it leaves the soil differs from the original one. When strongly polluted, soil stops to be the barrier against pollution (saturated sorptive capacity). Additional water influx from pipelines (soil waterlogging and bogging) Soil-substratum The barrier protecting from vertical penetration of chemical and biological pollution. Biogeochemical transfor¬ mation of substrate, wastes, and disposal sites Protective barrier may not function. Geochemical link between soil and substratum may be ab¬ sent (soil on communication conduits). Mosaic or downfall migration. Substratum is the cause of biological and chemical pollu¬ tion. Soil on disposal sites accumulates heavy metals and toxic compounds Soil-air Gas absorptive barrier for gases, including those pro¬ duced by motor transport, thermal power stations, and plants. Regulation of the gas com¬ position in the atmosphere and its cleaning Absorption of gases, including those from motor transport, plants, and thermal power stations. Dust production at the soil surface. Gas exchange deteriorates to soil compaction. Greenhouse effect under asphalt or under compact soil crust. The ratio between anaerobic and aerobic microorganisms changes. Additional gas influx from communication conduits Soil-biota Environment for macro-, meso-, and microbiola. The basis of bioproductiv- ity. Sanitary barrier Disturbance of the environment and reduction in its biodi¬ versity (composition, structure and functions). Lowered bioproductivity. Appearance of human-associated species. Appearance of pathogenic microorganisms. Deterioration of sanitary functions.
The extent to which soil is directly involved in transformation of the air composition is primarily determined by soil microorganisms, which species composition and number vary stronger under urban conditions compared to natural ones. Soil affects the heat and water dynamics in near-surface layers of urban atmosphere. Owing to its biogeochemical properties and huge active surface, urban soil is a sink of toxic compounds, such as heavy metals, pesticides, oil prod¬ ucts, etc. coming from the atmosphere into groundwater and rivers. Soil con¬ verts sewage water into groundwater and cleans it. In addition, it appears to be a sorptive barrier protecting water of rivers and ponds from pollution. In large cities and industrial centers, up to 70 to 90% of the soil surface is sealed with asphalt, occupied by houses and constructions. Consequently, polluted precipitation passes the soil body by and enters ponds and rivers through canalization (Fig. 2.3). Fig. 13. The effects of sealing of the soil surface on the ecological situation in the city.
As noticed by Hobert (1978), sealed landscapes are characterized by the strongest increase in temperature and its greatest fluctuations. Asphalt covering protects the soil from most pollutants, prevents pene¬ tration of rainfall to soil, and alters its water and air regime. However, micro¬ organisms may still live under the cover, so maintaining the gas exchange between soil air and the atmosphere. One of the negative consequences is the greenhouse effect because from soil sealing. Without natural aeration, soil be¬ comes waterlogged that promotes the increased humidity in basements and the destruction of foundations. High humidity in rooms and development of pathogens and fungi, which are very difficult to combat, cause health prob¬ lems for the inhabitants of lower stories. A high percentage of area sealed with asphalt, as found on boulevards, squares, and other areas, also has an adverse effect. Thus, anaerobic conditions “kill” the roots that penetrate under asphalt cover. Therefore, ecologically sound stone blocks or other permeable materials should be used to replace the impermeable asphalt cover. Soil is one of the necessary factors for plant growth. Ecologically badly managed, un vegetated urban areas are the source of the additional emission of solid matter into the atmosphere, so increasing the effect of toxic compounds contained in the city atmosphere. Urban soils should provide optimal conditions for plant growth in urban phvtocenoses. While urban soils are sufficiently provided with nutrients, their fertility is limited by the following factors: high pH (7.0 and more), overcom- paction and pollution with heavy metals, toxic hydrocarbons etc. (Soils in the Urban Environments, 1991). Acting through its sanitary and recreational functions, soil determines human life conditions in a city. Its sanitary and hygienic functions are very important for the city', since the soil possessing good antiseptic properties to kill pathogenic microorganisms and decomposes organic debris and metabolic products of living organisms. Human-made disturbances of the soil cover seriously disturb and de¬ grade the whole natural complex, so threatening the health and life of people in the city.
2.4. Optimization of Ecological Functions and Integral Qualitative Assessment of Urban Soils Types of land use are very important for the understanding of the ecological state of urban lands, since they effect the soil development in the city. In Moscow, there are the following categories of lands: • built urban and rural sites—residential areas (including yards, squares, kindergartens, schools, and lawns along highways; • traffic, trade and industrial sites (plants, factories, motor services, thermal power stations, warehouses, gasoline stations, aeration fields, highways, airports, railroads, etc.); • natural recreational and nature-protection areas (urban forests, for- est-parks, parks, boulevards, squares, natural monuments, etc.); • agricultural lands (arable lands, farms, nurseries, and experimental fields); • unused lands (wastelands, dumps, quarries, and badlands). Each category of urban lands includes: (1) sealed (impermeable) areas under houses, pavements, roads, ware¬ houses, industrial buildings, and other buildings and communications; the water-air exchange on these lands is disturbed; (2) open, unsealed (permeable) areas represented by soils and substrates variously disturbed by humans. These lands perform sanitary, hygienic, ecological, and biospheric functions, so maintaining human life standards and are subdivided into • vegetated areas, where soils still perform ecological functions (squares, parks, forest-parks, lawns, etc.) and • unvegetated or poorly vegetated areas sporadically covered mainly with ruderal species and herbs (waste lands, yards, etc.). Ecological functions of soils in these sites are transformed, degraded, and strongly disturbed. Such plots may be found in all categories of lands. Thus, the urban area includes various types of lands with different functional suitabilities. Together with general characteristics, each type has its specific prop¬ erties. Properties of urban lands also reflect the pattern and type of land use.
Functional zones of city and soils located within these zones are affected by socioeconomic, political, and administrative aspects of city planning. Therefore, it was assumed that the type of land use is the crucial factor of soil evolution in urban and industrial areas. After parent material (filled, washed, and mixed substratum) is deposited, urbic and natural factors begin to interact. As land is used, individual plots become linked with each other in a soil-geochemical landscape. The approach to estimation of the ecological status and quality of soils and the soil cover is modified dependingly on the type of land use and its spe¬ cifics. It comprises: • chemical pollution of soils; • degradation of humus status; • sanitary status of soils; • soil resistance to mechanical action and erosion; • degree of soil disturbance. Chemical pollution of soils is estimated by learning natural peculiarities of the area, the subordination of soil-geochemical landscapes, and sorptive properties of soils (acid-alkaline and redox conditions, humus content, and particle-size distribution). In addition, bulk and mobile forms of chemical compounds in the soil are compared to their maximal and estimated allowable concentrations. The estimation of the sanitary' status of a soil also varies with the type of land use and physicochemical and biological soil properties. The sanitary status of soils is determined by: • the possibility for pathogenic bacteria and viruses to survive, simulta¬ neously preserving their virulence; • the role of soil as an intermediate medium for development; • the ability' of soil to self-purification; • the content of toxic compounds in soil; • the ability' of soil for dust production; • soil radioactivity' (the excess over background values). Up to the present time, the standards of optimal functioning and quality' of urban soils have not been developed. The preliminary list of parameters necessary for the estimation of the ecological status (quality) of urban soils is given in Table 2.5. As standards we used GOSTs (state standards) for arable
lands within the zone of soddy-podzolic soils corrected in accordance with results of our studies of urban soils in Moscow. Some estimated values suit for estimating the status of all types of urban lands, while the others suit only for a specific type. Presently, the qualitative assessment of urban soils is insufficiently elaborated, while it may be used for soil and urban land rating. We attempted to make the preliminary estimate of the urban land quality by using several parameters (Table 2.6) ranging from soils that almost do not require reha¬ bilitation to practically unrecoverable ones (strongly degraded soils). Table. 2.5. Optimal properties of urban soils Functional zone Natural-recreational and recreational Industrial Criteria, parameters parks and forest-parks squares and boulevards lawns boulevards, squares, alleys lawns (1) Content of stones in the 0-2 5-cm layer, % <10 <15 <25 <15 <25 (2) Content of physi¬ cal clay (<0.01 mm), % 10-40 10-30 20-40 10-30 20-40 (3) Groundwater level, m >3-4 >2-3 >1 4-5> >3 (4) Thickness of the fertile layer, including that for planting pit, cm 10-75 30-75 >25 30-75 >25 (5) Humus content in the 0-2 5-cm layer, % 2-3 2-3 3-4 2-A 3-4 (6) pHwaier 5.5-6.5 5.5-7.5 6.5-8.0 5.5-8.0 6.5-8.0 (7) Bulk density in the 0-25-cm layer, g/cm3 0.80-1.10 1.15-1.20 1.20-1.30 1.25-1.30 1.20- 1.30 (8) Radioactivity, |jR/h <20 <20 <20 20-25 20-25 (9) Number of patho¬ genic microorganisms per gram of soil Not elaborated (10) Soil phytotoxic¬ ity (times relatively to the background <1.1 1.1-1.3 1.1-1.3 1.1-1.3 11-13
Table 2.6. Integral qualitative assessment of urban soils Categories Very good Good Mean Poor Veiy poor Parameters no reha¬ bilitation required easily rehabilta ted moderately rehabili- ated poorly rehabili¬ tated almost unrecov¬ erable without energy spending Morphological parameters (1) Thickness of humus layer, cm (percentage of decrease relatively to the background) 0 25 50 75 n/d (2) Degree of surface dumping, % sporadic <25 25-50 50-75 >75 (3) Content of stones in the 0-0.5-m layer, % sporadic <25 25-50 50-75 >75 Physical parameters (1) Clay content (<0.01mm), % 20-30 10-20 30-40 5-10 40-50 0-5 50-60 >60 (2) Bulk density, g/cm3 <1.2 1.2-1.4 1.4-1.6 1.6-1 8 >1.8 Chemical parameters (1) Humus reserves de¬ crease, % (relatively to the background) 0 25 50 75 100 (2) pH 6.5-7.0 5.5-6.5 7.0-7.5 4.5-5.5 7.5-8.0 4.0-4.5 8.0-8.5 <4.0 >8.5 (3) Content of heavy met¬ als, ГТА <16 16-32 32-64 64-128 >128 Biological parameters (1) Mesofauna diversity 1 1 i 1 -H-+ ++ + n/d (2) Level of active micro¬ bial biomass, times less relatively to the back¬ ground <5 5-10 10-50 50-100 >100 (3) Phytotoxicity, times less relatively to the back¬ ground <1.1 1.1-1.3 1.3-1.6 1.6-2.0 >2.0 Note: n/d is not determined.
CHAPTER 3 Soils and the Soil Cover of Moscow More than 800 years ago the present territory of Moscow and its vicinities were covered with mixed coniferous-broadleaved forests alternating with meadows, lakes, bogs, and flooded meadows within the valley of the Moskva River. The soil pattern was dominated by various podzolic and soddy- podzolic soils (Podzoluvisols) intermingling with bog and alluvial soils. Gradually, from century to century', the human activity transformed the area under natural vegetation The city grew by capturing nearby villages, cloisters, and posads (suburbs). Finally, the top layer of soil has been replaced by a cultural layer. The modern environment in Moscow is the result of the city develop¬ ment during the 18-20th centuries, when the city was growing by enlarging on suburbs Before the 18th century, Moscow had been limited by Zemlyanoi Gorod (“Gr >und town”) and occupied the area less than two thousand hec¬ tares. In the 18th century, the city grew within the area adjacent to the Moskva and Yauza river valleys (7 .2 thousand ha). Since the end of the 19th century', the city has started its eastern extension toward the Meshchera Lowland. In the 20th century, it has begun to develop northward to the Lik- hoborka River. In the middle of our century, the city has acquired the southern part of the high interfluve area of Teplv Stan. In the 1960s, the city grew westward (Fig. 3 .1). As noted by Moscow architects and city builders, the city has the form
of an “amphitheater” with a densely built-up, rela¬ tively low downtown. Around it, similar to an¬ nual tree rings, new zones of city consequently de¬ veloped. The first zones appeared during pre- and after-World War II recon¬ structions near the posts of Kamer-Kollezhskiy Val. Beyond them there is an intermediate zone dominated by five-storied (“Khrushchev-style”) apartment buildings con¬ structed between the 1950s and 1960s. The pe¬ ripheral belt with many- storied houses was built between the 1970s and 1980s. Table 3.1. Stages of city development Stages of city development Area of the city, km2 1. Kremlin walls of 1495 0.2 2. Walls of Kitaigorod of 1538 0.9 3. Fortifications of Bely Gorod (“White town”, modem Boulevard Ring) of 1593 5.6 4. Fortifications of Zemlyanoi Gorod (“Ground town”, mod¬ em Garden Ring) of 1630 to 1640 18.7 5. Kamer-Kollezhskiy Val between 1742 and 1864 72.1 6. Moscow Ring Railroad of 1917 212.1 7. Boundaries of 1935-1960 356.7 8 Boundaries of 1960 within the Moscow Ring Road 876.9 9 Boundaries of modem city 1091 0
Table 3.2. Land structure in Moscow in 1997 Type of land Area, thousand ha (%) Lands under residential and public buildings 44.4 (40.7) Lands of public use (streets, plazas, squares, parks, 15.5(14.2) boulevards, etc.) Agricultural lands 6.5 (6.0) Lands for nature conservation, tourism, recreation, his¬ torical and cultural monuments, and urban forests 15.8(14.5) Lands under communications 8.0 (7.3) Lands under industrial buildings, municipal services, 13.2(12.1) warehouses, and military installations Unused lands 20(1.8) Water bodies, land water-protection zone 3.7 (3.4) Total: 109.1 (100) Source: The Moscow Committee for Land Resources. The suburbs adjacent to Moscow have received the status of the protec¬ tive belt of forest-parks in 1935. The suburbs include 13 towns and make a unitary system with the city. They are separated by strongly urbanized rural areas, which preserved fragments of original nature. Urbanization, which has started in the second half of the 19th century', resulted in the integration of Moscow and neighboring areas The present status of the environment in Moscow is not only a result of the activity of the city itself but is also due to the strong influence of very' ur¬ banized Moscow region. Thus, nearly 30% of the surface of urban lands are open and partly planted. These areas are occupied with various urban soils (Table 3.2). 3.1 Physicogeographical Conditions of Moscow In contrast to natural ecosystems, the development of urban ones is deter¬ mined not only by natural processes but rather by the human activity. There¬ fore, all natural pedogenic factors (parent material, climate, topography, and vegetation) are strongly modified in urban areas.
3.1.1. Geology Moscow is situated in the center of a platform — a deep depression in Pre- Cambrian rocks filled with predominantly marine sedimentary rocks up to a depth of more than 1.5 km. The Moscow1 Depression is filled with Devonian limestones, dolomites, and gypsum. The highest point of their occurrence is 200 m below the sea level. Devonian rocks are overlain by Carboniferous limestones and red clays with a thickness up to 330 m. The outcrops of Carboniferous limestones are eroded and dissected by elongated depressions. They are filled with later deposits and overlain by dark Jurassic clays and sands, which, in turn, are covered by Cretaceous deposits. However, throughout the territory of Moscow they were mostly transported by glaciers and washed out by preglacial and glaciofluvial flows. Only up to a 52-m thick layer of quartz sands was preserved in the southwestern part of the city on the Vorob'evy Gory. 3.1.2. Geomorphology and Hydrology Modem relief of Moscow was sufficiently made by glaciations and erosional activity- of rivers. Till of Moscow and Dnieper glacial advances covers most of the city and its vicinity. In the geomorphological respect, the city mostly occupies moraine and glaciofluvial plains, flood plain, terraces, and landslide slopes. Moscow and its vicinity are situated on the joint of the Smolensk- Moscow Elevation, plains of the Moskva and Oka rivers, and the Meshchera Lowland (Fig. 3.2). The northern part of the city occupies the very southern edges of the Klin- Dmitrov Ridge and the Moscow-Smolensk Elevation and embraces the interflu¬ ves of the Moskva, Klyaz'ma, and Yauza rivers. The topography is hilly with rela¬ tive elevations of 40 to 55 m. Rocks mostly consist of sands and till clays. In the northern part of the city, the topography was smoothed by filling of gullies and bogged depressions. The thickness of fills is from 3 to 6 m. The southern part of the city encloses the area between the Moskva and Pakhra rivers. The elevation of Teply Stan is the highest place in the southern part of the region. It reaches 200 m above the sea level, or 80 m above the level of the Moskva River.
Fig. 3.2. Geomorphological scheme of Moscow (Likhacheva, 1997). (1) moraine plain; (2) glaciofluvial plain; (3)-(5) terraces of the Moskva River (1st, 2d, and 3d); (6) low flood plain; (7) landslide and creep slopes; (8) talwegs: (a) of ravines; (b) of technogenically buried river network; (9) rivers and lakes. ЕШ41Ш51 16 Ш 7E38 ^ 9 Steeply Ming, it constitutes the hills of the Vorob'evv Gory. Rolling topography is dissected by erosional valleys, rills, and ravines. During construc¬ tion, these sites were significantly cut off and filled with ground. The topography was the most strongly changed in catchment areas of small rivers. Somewhere more than 85% of ravine network were filled. The thickness of anthropogenic deposits reaches 20 m. The eastern part of Moscow belongs to the edge of the Meshchera Low'land. This is a flat, somewhere bogged plain with elevations from 20 to 40 m above the level of the Moskva River. Eastern and southeastern parts of the Moscow downtown, which are the lowest and flattest, border the Meshchera Lowland. Reclamation of these lands resulted in fills up to 6-m thick. Nevertheless, the territory is characterized by shallow groundwater and strong waterlogging. The Moskva River valley occupies more than 30% of the city area. This river has washed a wide, asymmetric valley within the city boundaries with three terraces recognized. The youngest is the 1st Serebryannoborskava terrace with ab¬ solute elevation of 126 to 130 m. The more ancient one is the 2d Mnevnikovskava
terrace with elevations of 130 to 140 m. The terraces are composed of sand and loamy sands with pebble lenses. The greatest area is occupied by the 3d Kho- dynskaya terrace, which has the highest elevations (absolute elevation of 135 to 140 m, or 30 to 35 m above river level). It is composed of ancient alluvial sandy and pebble deposits overlain by fine clays and peats. The valley of the Moskva River is characterized by strongly modified topog¬ raphy. After reservoirs and the Moskva-\blga canal were constructed in the headwaters of the Moskva River, the water discharge has increased by one cubic kilometer This makes up 60% of river discharge. Therefore, the water level rose by 5 m, so that the plain was partly flooded. Gullies and rills dischaiging into the river valleys were gradually filled. The mouths of small rivers were captured. In valleys, the thickness of fills reaches 20 m. Gullies and rills dischaiging into the river valleys were gradually filled. The mouths of small rivers were captured. In valleys, the thickness of fills reaches 20-m. \ Long-term economic and construction activities significantly transformed the natural topography of Moscow (Fig. 3.3). The land surface was leveled, so that the branched erosional network disappeared and new Iandforms were created. So, the leveling of initially rolling topography comprised: filling of gullies and flood plains, cutting of hills and slopes, and capturing of small river into underground collectors. These changes were especially evident during the construction of the subway in the 1930-1960s. Later the gullies were filled, and the depressions were leveled with sandy and loamy till taken from a 20- to 50-m depth of mines and tunnels. As calculated by Kotlov (1978), the volume of ground moved to Moscow' in 1967 was 211 m3. The greatest artificial Iandforms are pits and causeways of motor and railway roads. However, from the periphery to the downtown, the ground rises because of the thicker cultural layer. Nonetheless, the buried topography continues to affect soil formation by means of abundant concealed confining beds and sandy lenses. Therefore, the ter¬ ritory is characterized by unexpected groundwater discharges, waterlogging under buildings, and development of karst, and sinkholes. In addition, within the area of Moscow, the chemical composition and depth of ground water change. Some areas of the city became waterlogged after the natural drainage systems were ruptured (Osipov, 1994). In intensively developing areas, bogs were drained, the valleys of small rivers and springs w ere filled.
Fig. 3.3. Scheme of the assessment of changes in topography within the area of Moscow (Bakhireva et al., 1989). The degree of changes: (1) high (changed absolute elevations, filled rivers and lakes); (2) moderate; (3) weak (almost unchanged topography); (4) lost rivers and streams. The groundwater raise was also enhanced by leakage from fresh water and sewer pipelines, seepage from ponds, and pits for building, irrigation, etc. Ac¬ cording to the Geological and Hydrological Expedition, in Moscow, of 510 km of w aterways of small rivers, 290 km were eliminated. Only seven rivers preserved their waterways open, including the Yauza, Setun', Skhodnya, and Ramenka riv¬ ers. Other rivers were partly or completely captured into collectors. Throughout the city, more than one hundred small rivers, creeks, gullies, dozens of dead rivers, and more than seven hundred ponds were filled. All this modified natural catch¬ ment areas.
Due to the poor quality of potable, sewage, and heating water pipelines, nearly 400 cubic meters of water per day percolates through soil. In some places, leakage reaches 40% compared to 4-6% for the city on the average. So, more than 40% of the city area (especially in Central, Eastern, Northeastern, and West¬ ern Administrative regions) is waterlogged (groundwater is within 3-m depth). At the same time, the water level can be deliberately lowered to facilitate construction. This, together with sealing of the territory with asphalt and building of houses and industrial installations, decreases water reserves within the rooting zone and di¬ minishes the subsurface discharge. Major sources of environmental pollution of ponds and groundwater are aeration stations (filtration fields), contaminated surface runoff and land pollution. The surface runoff within the city depends cm the amount of atmospheric precipi¬ tation, flood water, and the snow cover pattern. High content of dissolved salts in precipitation and atmospheric dust, discharge of industrial and household wastes made fresh groundwater more saline (salt content is 2-3 g/1) at 85% of the city area (Pmsenkov, 1974). 3.1.3. Parent Materials Parent rocks that occur in Moscow and its vicinity belong to two large groups: cultural layers and natural grounds. Cultural layer is a historical system of strata produced by the human activity during several centuries. The cultural layer is formed through the ac¬ cumulation on the soil surface of different materials resulting from economic and living activities of humans. It also may originate from transformation of the topsoil during construction and landscaping, when the alien matter is added to soil. The cultural layer of ancient Moscow (tell) is subdivided into several historicolithological layers (Aleksandrovskaya et al., 1997). (I) The original soil — typically this is a soddy—podzolic soil developed cm glacial, glaciofluvial, and mantle deposits. It can be bogged and disturbed to a different degree by later events. (II) Above the buried soil lies the “organogenic"’ layer referred to the pe¬ riod of wood city construction in the 12-16th centuries. This is nearly 2-m-thick layer with clayey texture, high humus content, tim¬ ber and saw residues, and a small amount of inclusions of const rue-
tion material (brick and lime fragments). (1П) The last layer is overlaid by a thick “lithogenic” layer enriched with fragments of brick and construction lime. It is referred to the period of brick and stone construction in the 17-19th centuries. This layer has a lower humus content but is more sandy in texture. (IV) The modem cultural layer contains even a greater amount of con¬ struction residues; it can be overlayed by asphalt concrete cover, otherwise thick urbanozems develop in its upper part (Fig. 3.4). The cultural layer of Moscow based on loose loamy-sandy brownish sediments includes quite different materi¬ als: brick fragments, stones, construction waste, abandoned foundations of build¬ ings, basements, wells, wooden decks, boulder and asphalt covers, and home ap¬ pliances. It also contains abundant de¬ caying organic residues. For example, the cultural layer represents a heterochronous system of buried urban soils, including paleourbanozems (Table 3.3). The cul¬ tural layer is continuous in the downtown — within the Garden Ring, while it is shallow and discontinuous in the areas of rccent construction. It occurs as rare spots and strips typically in the valleys of filled and captured rivers, ravines, quarries, and other human-made depressions. The territory of ancient large cities, such as Moscow, Novgorod, and Kiev can be divided in two major zones. The first is the zone of an ancient settlement with a well-developed cultural layer favorable for the formation of thick ur¬ banozems. The second one is the zone of recent city development with a poorly developed cultural layer. These areas may preserve variously disturbed natural soils, while shallow' poorly developed urbanozems or urbotechnozems (former called soils-gmunds) develop on fresh and old sediments. Fig. 3.4. Cultural layer.
Table 3.3. The composition of Moscow tell according to Kotlov (1962) Material Percentage Sand 67.6 Loamy sand 10.0 Rock fragments and construction waste 10.0 Loam 3.45 Clay 1.24 Organic matter 3.0 Ancient constructions 4.35 In the ancient part of Moscow, the cultural layer thickness ranges within 2 to 3 m on the watersheds and from 7 to 10 m in depressions. The maximum thickness of the layer (20 m) was found on Vasil'evskiy Spusk near the Kremlin. The cultural layer of Moscow is stratified, stony, has an alkaline reaction and an elevated content of phosphorus and organic matter. It is cal¬ careous and somewhat enriched in heavy metals (Table 3 .4). Table 3.4. Chemical properties of the cultural layer in the center of Moscow Horizon, depth, cm Century pH water Humus, % Loss by ig¬ nition, % COz of car¬ bonates, % РЛ, mg/kg A. 25 20 8.1 4.40 9.34 1.90 26.0 A. 70 18-19 7.9 3.45 9.03 2.86 52.4 El. 100 18 7.8 2.90 8.00 1.19 61.1 115 18 7.9 1.72 7.77 3.85 50.4 145 17-18 8.2 1.36 7.12 3.50 29.3 A. 160 17 8.0 2.34 6.84 1.44 49.0 170 17 7.9 1.46 6.41 0.73 52.0 195 17 8.1 1.48 7.16 3.09 41.8 195 16 7.5 3.08 7.85 0.40 63.1 Source: Aleksandrovskaya, 1996. The oiganic matter consists of detritus, humus, and abundant inclusions of wooden constmctions and chips in waterlogged layers. Limestone and lime widely used in the 17-18th centuries are the principal source of СаСОэ. As carbonates migrate downwards, they change the initially acid reaction to al¬ kaline. Additions of household wastes increase the phosphorous content by 100 to 200 times compared to natural soils (from 1-5 to 200-550 mg/100 g of soil), so that viviamte is often found in the cultural layer. It foims bright
blue films on the faces of bricks, archeological artifacts, and soil peds (Aleksandrovskaya and Aleksandrovskii, 1997). As for macroelements, biogenic potassium accumulates in the cultural layer and ancient soils of Moscow due to decomposition of wooden materials, frequent fires, and application of furnace ash as a fertilizer for kitchen gar¬ dens (Table 3.5). Table 3.5. Content of macroelements (%) in the cultural layer in the cen¬ ter of Moscow Horizon, depth, cm Century S1O2 АЪОз FcjOj TiOz CaO MgO k2o NazO A. 25 1995 70.3 10.5 5.11 0.59 9.42 0.95 1.97 0.5 A. 70 18-19 63.3 10.0 5.69 0. 73 16.0 0.92 2.10 0.5 El. 100 18 71.5 10.6 4.99 0.72 7.38 1.16 2.42 0.5 115 18 67.5 8.30 4.19 0.52 17.3 1.17 1.82 0.5 145 17-18 67.8 11.0. 4.39 0.64 11.4 1.11 2.50 0.5 A. 160 17 70.7 10.8 5.03 0.67 8.28 0.76 2.60 0.5 170 17 72.5 11.9 4.88 0.74 5.41 1.04 2.37 0.5 195 17 66.1 11.5 4.96 0.63 11.7 1.60 2.36 0.5 250 16 75.9 9.8 4.01 0.74 4.63 1.26 2.41 0.5 270 16 78.1 10.9 3.27 0.90 2.25 0.77 2.73 0.5 Source: Aleksandrovskaya, 1996. The human activity increased the content of different macro- and microele¬ ments in the oiganogemc cultural layer (wooden construction of the 16th and 17th centuries) and in above-lying wastes derived from lime and brick (the 18th and 19th centuries, Moscow deposits). Thus, the fraction of silica (63-73% Si02) in the total composition of the cultural layer relatively decreases, while the fraction of CaO and K20 increases up to 7.5-17.5 and 3%, respectively. Locally, ancient soils of Moscow were polluted with heavy metals and arsenic. Natural substrates. The whole range of sediments and rocks typical for this region occurs in the city. They are composed of a wide range of deposits: (1) till deposit; (2) mantle-postglacial loams; (3) glaciofiuvial and paleoalluvial sandy deposits; (4) contrast-texture deposits; (5) modem alluvial and lacustrine deposits; and (6) the eluvium of original pre-Quatemary rocks. The properties of substrates and their mixtures affect the soil properties, pedogenesis, and soil functions. There¬
fore, as noted by German soil scientists, the soil properties are mainly conditioned by properties of the substratum. Till has been deposited during the Mindel and Riss (Riss I and Riss П phases) glaciations, which had covered the territory of Moscow. The Wiirni gla¬ ciation had not reached the city vicinity being stopped north. However, its melt- water significantly promoted formation of the river valleys. Till of the Mindel gla¬ ciation occurs sporadically. It is composed of grayish-black, more rarely reddish- brown loams and loamy sands and contains pebble and boulders predominantly of local sedimentary rocks. Intermediate till (Riss I) is coarse, partly very compact grayish-brown loam with abundant boulders. Till forms a mantle (5 to 20-m thick) on the watersheds and penetrates along the slopes to river valleys. Upper till deposited after the Riss П stage consists of reddish-brown loamy-sandy or loamy deposits. It is more sandy and loose and contains abundant boulders. It is overlain by buned lacustrine deposits of the last Riss-Wurm inteiglacial. The composition of till significantly varies by the abundance of boulders and fine rock fragments and by their clay content. Being poorly sorted, till often con¬ tains fragments of calcareous rocks. Most deposits have a neutral reaction. Mantle loess-like loams are well sorted both in space and along the soil pro¬ file. They do not contain boulders, fine rock fragments, and coarse sand. Their composition is dominated by the fraction of coarse silt (0.05-0.01 mm) that com¬ prises 40 to 55% of the total mass of sediment. Glaciofluvial and ancient alluvial deposits are composed of differendy grained sands with rare pebbles. Sometimes they contain bands and lenses of gravel and pebble. On catchment areas, the thickness of glaciofluvial deposits ranges from 1 to 5 m, while it is 20 m and more in the ancient valley of the Moskva River. They also can contain fragments of calcareous rocks. Contrast-texture deposits, e.g., mantle loams above till, sand above tilL etc. They also affect formation of urban soils by changing water and temperature re¬ gimes, downward migration of compounds, profile distribution of roots, etc. Recent alluvial and lacustrine deposits occur on terraces of river flood plains. The upper part of recent alluvium is composed of brown and reddish- brown sandy loams and loams, sometimes replaced by fine and coarse clays downwards. Pre-Quaternary eluvium and slope deposits occur locally. Their composi¬ tion closely relates to the geological structure of slopes and watersheds. They are enriched with fragments of calcareous rocks on the outcrops of limestones, while
they are darker and contain more clay on the slopes with outcrops of black Juras¬ sic clays. In cities, substrates are modified to a significant depth, because foundations of buildings stretch to a depth of 35 m, while the subway is at the depth of 60 to 100 m. Formation of urban parent materials can occur through several processes, namely, moving, digging, and filling. These processes do not merely mix different geological strata but also change subsurface and, hence, geochemical flows. Filled grounds are the loosest. Soils developed on filled grounds are characterized by deep penetration of oiganic matter (including its dangerous compounds), nutrients (especially phosphates), and heavy metals. In contrast, natural soils are high in these pollutants only within the topsoil. Some urban areas develop on dredged grounds, for example, in the Marino district. Because of abundant construction wastes filled and mixed grounds are typically alkaline. Thus, urban soils—urbanozems and urbotechnozems — have the following parent materials: (1) cultural layer, (2) mixed and transported sediments and remains of natural soils; (3) fresh fills or dredged grounds. The above-mentioned groups should be subdivided into ecologically safe and toxic grounds at the lower level. 3.1.4. Climatic Peculiarities The climate in cities is distinguished from that in their vicinity. The urban climate somewhat resembles the climate of regions located at a distance of 200 to 300 km southwards. These differences are attributable in large to the following features of cities. As the area under houses and infrastructure ex¬ pands, the natural course of air and soil temperatures, precipitation pattern, moisture content, solar radiation, and other meteorological conditions change. This is primary because of a huge number of stony constructions, extensive surface of steel roofs, pavements, industrial installations, heating communi¬ cations, etc (Fig. 3.5). Heat and dust focuses forming in the urban atmosphere essentially af¬ fect the air temperature and precipitation pattern. Mean temperatures in the downtown are warmer than those in suburbs. Daily minimum temperatures also rise. Fluctuations of daily temperatures are not so noticeable in the city
fresh air J> used J) air water, food, energy, industrial materials, and products <r industrial products and wastes Tj) <ireen /one residential zone of the outskirts industrial zone residential zone center Climate umo of .sun shimnii j\crage annual (emperatuic .иегацс annual wind \ clocit> ■uni and iniciisit\ of precipitation relati\e air huimiidit\ dust in the air time fif fog existence ' eycialidii decree of coverage ‘)У’л, species' ai ieis introduced species 10-15% \ arietv •■> l*iotfi|H ' soils open suiiat'e .immmt uf пиюрицп 111 inHlci/l'IDS by 10 - 15% In 1 - 1,5°C ti\ 20 - 31) % by 10-15% by 10- 15% 10 times as hij:h by 30- 100% 10 and less 20 % and more 25 % and more Fig. 3.5. Ecological transect: Moscow city — suburb. as they are in its suburbs. Denser built-up and expansion of sealed areas from 20 to 50% increase the difference between maximum summer temperatures in the city and its outlying parts from 5 to 14 °C. The soil surface temperatures are maximally 10 °C higher than those on neighboring areas. Furthermore, urban soils are additionally warmed from in¬ side by city- heating communications. The snowmelt occurs in Moscow ear¬ lier, so, in some years, the snow cover persists only for two to three months (instead of four to five months in suburbs) that increases the duration of the growing season. We analyzed data on air and soil temperatures and precipitation ob¬ tained by observations made in 1988 at the Balchug (the center of Moscow)
and Tushino meteorological stations at the edge of the city (Figs. 3.6 and 3.7). In addition, the temperatures in vicinity of Moscow were measured in the park of Leo Tolstoy's museum-estate (Khamovniki). Soil surface temperature meteorological station Balchug meteorological statnin Tushino —л— park Khamovniky 35 Air temperature Fig. 3.6. Dynamics of air and soil surface temperatures in Balchug and Tushino meteorological stations and in the park of Leo Tolstoy’s Museum estatein Khamovniki from April to November 1988. The difference in air temperature between center and peripheral parts of Moscow is significant (4 to 5 °C) during spring, summer, and fell. These dif¬ ferences are reduced to 2 to 4 °C in winter. The course of temperature of the soil surface principally follows the change in air temperature. However, dur¬ ing warm periods, the temperature of the soil surface is higher than that of the air; while during cold periods, the temperature of the former is lower than that of the latter. In the city center, the temperature of the soil surface was by 3 to
—meteorological slalion Tushino —■—Khamovrtiky park Aug. Sept °ct- Nov. Fig. 3.7. Dynamics of soil temperature at the depth of 20 cm at Tushino weather station and in the park of Leo Tolstoy's museum-estate in Khamovniky from Augustto No¬ vember (1988). 5 °C higher from November to March. In August, the well-shaded soil sur¬ face in the park of Leo Tolstoy's museum-estate was cooler than soil with open surface at both Moscow meteorological stations in the downtown and suburbs (sometimes by 10°C and more). In fell, this difference gradually dis¬ appeared, so the temperature of the soil surface in the paik was higher by 3 to 6°C and more. In Tushino, the soil temperature at a depth of 20 cm increased up to 20°C in summer. Later it gradually decreased to 0 to 1°C and remained like this until spring. At all three sites, the soil temperature at a depth of 20 on was actually the same from August to December. In the center of Moscow, the sum of air temperatures was higher by 50 to 100°C compared to the city edge. More conspicuous was this phenomenon in July. Total precipitation was usu¬ ally 100 mm greater in Balchug than that in Tushino. The climate of Moscow is also characterized by higher (by 5 to 10%) precipitation and a lower influx of solar radiation reaching the soil surface (by 15 to 39%). In winter, the frequency of days with fogs increases by two times, while the mean wind speed is by 20 to 30% lower than that on neigh¬ boring rural areas. Although the total precipitation is higher in Moscow than in rural areas, its amount really entering the soil is less, owing to rain water discharge into collectors and to snow removal. “Overheating” of the city and the “greenhouse” effect result from heat emitted during fuel combustion, smog that prevents diurnal insolation, sparse vegetation, and greater areas
under asphalt, houses, and other surfaces that poorly absorb and retain water. The heat impact of industrial and municipal enterprises and heating commu¬ nications produces the effect of so-called “heat domes”. In this case, sedi¬ ments and groundwater are wanned to a depth of 60 to 100 cm and below. The distribution of snow cover essentially differs in the city and natural areas. Depending on site, snow in the city can be either removed or exces¬ sively accumulated by people and wind. Plots cleared from snow develop un¬ der conditions similar to those found in arid cold desert. When developed, its stony primitive deflated soils are covered with sparse “scale and pillow” vegetation. Plots with excessive snow cover, especially in shaded sites, have a microclimate and seasonal regime (phenophases) close to forest and forest- meadow landscapes and associated pedogenic processes. Frost heaving of soils and soliQucdonal landslides can develop in both cases. The major contributors to air pollution in cities are motor vehicles, in¬ dustrial enterprises, and construction sites. Poor weather conditions signifi¬ cantly stimulate the emission of toxic compound by industrial enterprises. Thus, according to the data of the Moscow Center for Monitoring of the En¬ vironment (1996), the concentration of: • nitrogen oxides increases by five to ten times throughout the city; • carbon dioxide and finely divided solids increase by two to five times in the Southeastern administrative region; • sulfur dioxide increases by two to five times in the Northern and Cen¬ tral administrative regions; • formaldehyde increases by two times in the Eastern and Central ad¬ ministrative regions; • ammonia increases by two and more times in the Central administra¬ tive region. Air pollution by motor vehicles produces almost 80% of the total emis¬ sion. Recent observations show that the level of air pollution is high and gradually increases. Urban climate affects physicochemical and biological processes in soil as well as its water-physical properties. Elevated temperatures cause a cer¬ tain water deficit in soils and sediments. Since temperature of groundwaters, soils, and air is generally higher in the downtown, there is a greater probabil¬ ity for the rise of salty groundwater there.
3.1.5. Vegetation Natural areas of Moscow make one complex with those of Moscow region. They are composed of lands of unique ecological, landscape, historical, and cultural importance. These are Losiny Ostrov natural park, Bitsa natural park, a water-landscape system of Krylatskoe-Serebryany Bor-Strogjno, historical and cultural ensembles of Kolomenskoe, Tsaritsyno, Kuskovo, etc. (Fig. 3 .8). These vegetated areas perform important functions of environment improvement along with sanitary, hygienic, recreational, and aesthetic ones. There are more than 36 forested areas in Moscow. Their size ranges from 5 to 3000 ha: Losiny Ostrov (3000 ha), Bitsa forest (1800 ha), Iz- mailovskiy forest-paik (1437 ha), Kuz'minld (962 ha). Twelve massives have the size of 150 to 600 ha, while the rest territories are less than 100 ha in area. Dominant tree species are birch (39%), pine (21%), linden (18%), oak (10.5%), aspen (4%), and spruce (2%). Parks are absent almost at 20% of the city area. Vegetation of parks, boulevards, and squares is represented by poplar, linden, maple, elm, chestnut, birch, and other species. In city squares and parks, the total amount of tree and shrub species varies from 4-6 to 15-18. The state of vegetated urban areas depends on many factors that domi¬ nate the vegetation of Moscow in a way as it is in other cities. The most es¬ sential factors are technogenic and recreation impacts and the soil properties. According to data of the Moscow Committee for Nature Protection, only in 1992, nearly 1,200,000 t harmful compounds, including 150,000 t nitrous oxides and 60,0001 sulfur dioxide, were emitted into the atmosphere of Mos¬ cow. The content of chlorophyll decreases, plant tissues become yellow and ocherous in color. They are also covered with red-brown and brown spots in¬ dicating necrosis. Within the city limits, the degree of damage differs for leafy and coniferous species. The most damaged are coniferous (pine and spruce) stands, whose needles are covered with brown spots and bums. Their canopy becomes thinner, while the tops of their boles die. According to data on the state of nature in Moscow {About the Status..., 1993, 1996), the largest aure¬ ole of pollution is in the southeastern part of the city. In most parts of the city, vegetation is characterized by the moderate degree of damage. The data from state report {About the Status..., 1993) proved the data published by Afonina
Fig. 3.8. Scheme of natural—recreational zones of Moscow, namely: 1 — Krylatskoe—Serebryany Boi^Strogino wateiHandscape system; 2 — Fili-Park; 3— Park of the Timiiyazev Agricultural Academy, 4 — Main Botanical Garden; 5 — Sokol’ni- ki park; 6 — Losiny Ostrov park; 7 — Izmailovskiy forest-park; 8 — Kuskovo; 9 — Vo- rob’evy Gory, 10— Neskuchny Garden and Goririy Park for Culture and Rest; 11 — Bitsa for¬ est-park (northern partX 12— Tsaritsyno; 13— Kolomenskoe, 14— Kuz’minkiparic. et al. (1990) about a direct relationship between the degree of plant damage and the accumulation of heavy metals in plants and soil. Although leafy forests are resistant to recreation, they are also vulner¬ able to diseases. Presently, leafy species are strongly damaged and partially decline along highways and around industrial enterprises.
According to rough estimations, the area of vegetated lands in Moscow is 15 to 17%, so providing only one-third of the area required for city popula¬ tion (Table 3 .6). Vegetation is very unevenly distributed throughout the city. In central districts of the city, the vegetated area ranges from 5 to 1 m2 per capita. Together with that of yards it does not exceed 4 to 5 km2. Its sanitary role is insignificant. Table 3.6. Distribution of areas under vegetation within the Moscow Ring Highway Category of vegetated lands Percentage (1) Forest-parks, urban forests 40.1 (2) Public parks, including: 59.9 parks for culture and rest 38.8 children parks 0.7 squares and boulevards 14.7 gardens 1.7 sport parks (stadiums) 4.0 Overall planted area 17.0 Source: Mashynskiy and Semenova-Prozorovskaya (About the Status.., 1993J. In the last years, the protective belt of forest-paiks around Moscow was intensively destroyed and occupied by constructions. According to ecological standards, the optimal ratio between the area of a big city and its protection belt should be not less than 1 to 5. Many Russian cities maintain this ratio; this ratio for Moscow is 1 to 1.5. The flood plains of small rivers were significantly disturbed. They are better preserved on the city periphery. Preserved areas along the Yauza River and other rivers are not managed. Some are used under unauthorized building and dumping. Furthermore, they arc subject to further fragmentation and de¬ struction, especially when surrounded by residential areas. Presently, ineffec¬ tively organized industrial enterprises, public utilities, and warehouses occupy up to 60% of the areas around the Moskva, Yauza, and other rivers. There¬ fore, the city cannot use nearly 3000 ha of territories suitable for landscaping and recreation. According to preliminary estimates, the state of vegetation attests to a quite unfavorable ecological situation, especially in the city center, within a
short distance from ecologically harmful enterprises, and along highways. Trees are mostly damaged. The share of declining trees is high on streets and squares. Natural elanents in urban complexes are very much different with respect to their ecological conditions. Their properties are best to observe in city and forest- parks, especially in old paries. Although, being managed by humans, they preserve natural biological cycling. Specific types of plant communities are created by hu¬ mans. Their ecological functioning is primarily controlled by humans, which re¬ move fallen leaves, apply organic and mineral fertilizers, etc. Urban vegetation does not completely lose its zonal features, and an- thropogenization in cities is controlled by zonal and climatic conditions (Kotlov, 1977 and 1978). In the forest zone, it acquires some “southern” features with appearance of xeromorphic elements. The climate of the city affects the whole Moscow region. So, there is a noticeable tail of air pollution and the temperature anomaly in northeastern, eastern, and southeastern directions. The precipitation pattern is changed within 90 to 100 km from Moscow. Within the distance of 30 to 40 km from Moscow, forests often suffer from diseases. Summarizing the data of ecologists, the following unfavorable factors affect the vegetation of Moscow: • High pollution, smoke and dust content in the air and chemical, bio¬ logical contamination of surface and ground waters. • Disturbance of soil temperature and water regimes. • Changes in physicochemical and physicomechanical properties of soils. • Excessive areas under asphalt pavement on streets and squares that deteriorate air and water exchange of rooting systems of trees. 3.2. Soils of Moscow 3.2.1. Morphology of Soils Today in cities, including Moscow, most of the area with natural soils has been destroyed or drastically changed (Blume and Runge, 1978; Dolotov and Ponomareva, 1982; Rokhmistrov and Ivanova, 1985; Short et al., 1986, Bridges, 1989; Stroganova etal., 1990, 1993; Agarkova et al., 1991, Craw/, 1992)
One could hypothesize that the present territory of Moscow once had the soil pattern typical for southern taiga dominated by coniferous¬ broadleaved forests. Watersheds of moraine and glaciofluvial plains were oc¬ cupied with various podzolic and soddy-podzolic soils, which had different degrees of podzolization, gleying, and humus accumulation. In addition, sur¬ face- and/or contact-bleached horizons could be found. These podzolic soils occurred in association with bog-podzolic and high-moor bog soils. The greatest diversity and complexity of soil profiles were within the top 0.5 m. Forest soils had well-developed, often raw-humus forest litter. Soddy-podzolic soils also occur on the slopes of drained terraces, somewhere composed of lithologically contrast-texture deposits or underlain by calcareous rocks. Different alluvial soddy, meadow, and bog soil were formed on the flood plain of the Moskva River. Our studies revealed that nowadays natural soils were left only as “islands” within urban forests and forest-parks (Losiny Ostrov, Fili park, etc.). Forest-paiks are dominated by natural soddy-podzolic soils with differ¬ ent humus content and degree of podzolization and disturbance. The soil pro¬ file of these soils has the following arrangement. Forest litter (O) is up to 3-cm thick. It overlays the humus horizon (A) 5 to 10-cm thick, which is fol¬ lowed by eluvial (El), transitional (E1B), and a series of illuvial (Bt) horizons. They gradually transit into parent material (C) or underlying rock (D). Somewhere in parks and forest-park bogs, bog-podzolic, and alluvial soils with a different degree of disturbance (urbo-soils) can occur along with urba¬ nozems. Modified variants of urbo-soils combine properties of the undis¬ turbed subsoils and human-affected topsoils. Urbo-soils differ in the way of their origin (filled, mixed), humus content, degree of gleying and profile dis¬ turbance, amount and composition of inclusions (concrete, glass, toxic wastes, etc.). In other parts of Moscow subject to stronger human impacts, urban soils developed. As shown above (Chapter 2), they can develop on natural parent rocks, cultural layers, and filled or mixed grounds. A peculiarity of urban soils, especially in the city center, are abundant inclusions of human- made materials (e.g., solidified lime solutions, slag, and old bricks) found in middle and lower parts of the soil profile. Urbanozems developing on the cultural layer have a humus-enriched topsoil. Morphologically, they differ in a set of filled layers and in their thick¬
ness. The soil profile is characterized by alternating loamy sandy horizons and sandy and loamy bands. The number of horizons ranges from one (homogeneously mixed layer) to six and more. Soils developed within the limits of the thick cultural layer are found in the center of Moscow. There urbanozems have a thickness from 40 cm (when underlain by concrete plate or residues of old footings) to 120 cm and more. In old parks (the Yusupovskiy park, a paric near the old building of Moscow State University on Mokhovaya Street), urbanozems have a thick humus ho¬ rizon. Most of the urbanozems are characterized by the absence of genetic A and В horizons. The soil profile contains different artificial layers varying by color and thickness. This is testified by short transitional zones and even sharp boundaries between them. Skeleton is composed of construction and household wastes, crushed brick and glass, pieces of asphalt, charcoal, etc. combined with industrial wastes, peat-compost mixture, and fragments of ho¬ rizons of natural soils. Some layers completely consist of waste materials. Types of the morphology of profiles of these soils are shown on Fig. 3.9. 3.2.2. Water and Physical Properties of Soils Soils of Moscow differ from soils of adjacent areas not only in morphology but also in texture and physicomechanical properties. While during formation of natural deposits particles become naturally sorted by shape and size, urban soils often develop through arbitrary mixing of different materials. We do not know well properties of these deposits within the limits of Moscow. Some producing companies reported that many deposits found in the city are capable of subsidence due to self-compaction and karst formation re¬ sulting in deformation of buildings. Poor knowledge of the composition and properties of different types of urban soils also prevents giving recommenda¬ tions on their use and estimation of their effect on geochemistry of the urban environment. When studying physical properties of surface horizons of urban and neighboring soils, it is revealed that they differ essentially from natural soils. In the first turn, their water-physical properties change (Table 3.7). Soil texture is a very important ecological property, which determines productivity, permeability', and water-retention capacity' of soils. Sandy and
soddy- podzolic soil ■ jt: LUiMfeli* ;ff yfjvel Slightly disturbed soddy-urbo- podzolic soil Strongly disturbed soddy-urbo- podzolic soil j Urbanozem Konstruktozem Replantozem Nekrozem Fig. 3.9. Types of urban soil profiles
loamy sandy soils when warmed by sun in spring typically thaw faster. Clay soils have a higher sorption capacity and provision with nutrients. All these properties directly relate to humus content, ecological (sorption, production, water-air, etc.) functions of soil and microbiological processes. So, sandy soils always contain fewer microorganisms, including pathogens; they are chemically purer, etc. Table 3.7. Physical properties of topsoils of urban soils Properties Soils Soddy-podzolic soils Urbanozems Soil hardness, kg/cm2 20-25 40-45 Pore space, % 45-55 30-40 Bulk density, g/cm3 0.9—1.2 up to 1.8 Field water capacity, % 14-20 5-14 Urbanozems are featured by lithological discontinuity, i.e. by abrupt change in structure, texture, bulk density, aeration, hydraulic conductivity’, available water content, and chemical composition of soil material. For urban soils, textural stratification of their parent materials controls transport of soil water and compounds solved in it, acting as a sealing and capillary barrier. Many urban soils contain layers of solid angular fragments. Therefore, such substrates are characterized by weak root penetration and rare occurrence of earthworms. Particle-size distribution in urban soils is primary determined by their occurrence on certain landforms and the degree of disturbance of their soil profiles. In central, eastern, and southwestern parts of Moscow, soils pre¬ dominantly have loamy sandy (sometimes sandy loamy and loamy) texture with significant admixture of stones. Stones sometimes comprise 50% and more of the soil volume (Fig. 3.10. Tables 3.8 and 3.9). All soil samples from landslide slopes and terraces of the Moskva River are dominated by the sandy fraction. It makes up to 50 to 80% of the total and is distributed evenly or “accumulatively” along the soil profile. The clay fraction (particles less than 0.001 mm) and the physical clay fraction (particles less than 0.01 mm) are found approximately in equal amounts (not more than 10%). Urbanozems almost lack clay differentition.
Table 3.8. Particle-size distribution of the fine earth in urban soils developed on sandy and loamy-sandy old alluvium on the river terrace (% per absolutely dry weight basis) Particle-size distribution, nun, % I <0.001 OnOOOJ0® — 40 \0 irj \0 2 00 PON- 2 оог^»л О 00 <№^ 00 ^ ON 'Al (N 00 hvoaiK -а -атэтэтэтэ ^2 "S'S "2 "S'S ТЗ ТЭТЭТЭ Ъ'й'ё'й ■O ТЭТЭТЭ б'й'й'й 1 TOO 0-500 0 On О 40 (N —; —; — О (N О r~. Over4; otVi- “О тг ТГТГ fz> oori 1Л 00(Nf“i — 0 — 0 * ?->* * * * о Hoooo oo 10.5* 8.5* 8.4* 12.5* 10.5* 8.8* 16.1* 12.8* Isooo-ioo Onc*^—■ (NtT‘/'4 СП (N (N ГП (N 00 (NOOvO Tf un i/“i О — 1Л[^1Л rn oirioi On О 1Л oirirs p 9oqqo ^ "sT (N fi tj-' ЧО 00 Of — (N SO (N’t'O О — <N — 10.05-0.01 10.4 8.2 8.8 15.8 23.6 0.9 ^ On(N^ iri wnOO.^ Г- (N —^ 7.8 5.8 11.5 12.8 «.5 13.0 8.0 10.2 27.0 41.0 11.0 6.0 10.0 10.0 —» t-^oor-; DO S(NOi «Т OOnnO rr (N 00 Г-’ m О ? ю rN О OO'OnnON К>ЛГ)0\00\ »/"» (N xr^on O' o’ <л — — (N — —; 00 —4p rn rSrSoo [N (N^rri m чОтг'О О (NO On (N (N<N — poop ОО ■^r Siridrid Г“> — (N —(N(N On f Г- О rn odo’S in Г-- rS чбоо’оо >• Г-- 1-0.25 1 —> ту чО'О'П'П 00 i/S г-* Ю Г-- vO > 00 ON —« О 00 (NON "3* С*1 ТГ \D On On с*1 О — чОГПтГ У“» Hi (N lT» ООО — —< Ov rf чО 1Л Tjin<n q0oooq rN н“> S oo" — rN 'ЛГ^'Л^О ON 40 — 00 /S (N00 ON rN (N — — (N rn(N4p — — On HCI losses,% 00 — \D Г". (N nO — <N —— (N — On f c*n/-» (N (N <N — Ш 00 00 00 rS i/S c*S(N тг (N^n ^ тг тг H ■о ТЭ^^ТЭТЭ T3 ТЭТЭТЭ Hygroscopic, water, % (N —(N'O^nr-' ОтГППОГ4 — ooo —с? m (N on e*i О 00 чО tj- — ООО 1.16 1.11 0.85 0.93 >»nwo Tj- On 00 — —oo ■о ТЭТЗТЗТЗТЗ сЭ ■а -a-a-a c2 '5'5'5 Depth, cm 0-10 10-30 30-75 58-75 75-122 122-148 0-40 40-63 63-71 71-110 0-10 10-20 30-60 60-115 0-10 10-20 35-50 90-130 0-3 3-22 22-39 39—42 42-60 60-70 0-13 13-68 68-83 83-120 0-10 10-34 34-65 65-80 Horizon «Sjssaa Ulha U2iha2 B1 B2 1 ^ ±3 (Nm Э D!=> 3 У S c) Э ^ Ulh U2h U3h U4 U5al U6al Ulh U2 U3 U4 Alu Layer 1 Layer 2 Layer 3 Pit no. Functional zone. Soil. 1 a илО vS о о о СЧрнСО ft. 10. Park. Urbanozem 13. Residential area Urbanozem 17. Residential area. Urbanozem 13g, Square. Urbanozem 33g, Square. Urbanozem .1 §§ rnooft: * particles less than 0.005 mm. Note: n/d is not delerminaled.
Table 3.9. Partide-size distribution of the line earth in urban soils on till and mantle loams (% per absolutely dry weight basis) Pit no. Functional zone. Soil Horizon Depth, cm Hygrocopc, w^er, % на loss*s,% Particle-size distribution, % fractions, mm 1-0.25 4 s О О 0.05- 0.01 0.01- 0.005 0.005- 0.001 <0.001 23. Ulh 0-3 2.59 6.4 18.1 14.3 33.0 7.2 10.2 10.8 Residential U2ihal 3-30 1.30 3.8 4.8 8.6 51.1 10.3 8.3 13.1 area. U3 30-70 1.63 3.7 10.9 18.1 46.8 9.6 6.7 4.2 Urbanozem B2 70-120 2.27 4.8 4.9 8.5 44.3 8.0 7.7 21.8 39. Lawn Uldal 0-8 0.49 10.2 42.6 33.6 7.2 0.6 0.8 5.0 between U2h 8-22 0.60 10.0 47.1 33.0 4.8 1.1 0.3 3.7 tracks U3ha2 22-35 0.53 7.7 42.6 33.7 8.6 1.2 0.7 5.5 Urbanozem U4 35-55 0.86 8.4 36.5 22.5 15.9 3.3 3.4 10.0 B1 55-77 0.84 7.0 44.2 23.3 10.6 3.1 1.0 10.8 B2 77-120 1.15 3.6 24.6 16.1 28.8 5.4 5.7 15.8 BC 120-170 2.11 3.2 12.6 4.3 42.6 9.5 10.4 17.4 4. Park. Ulh 0-14 2.28 3.9 6.3 49.8 4.2 7.0 10.0 18.0 Soddy- E1B 14-48 2.56 3.4 0.7 3.5 45.5 8.9 8.8 29.2 urbo- B1 48-80 2.13 3.4 n/d 4.2 45.8 8.0 8.4 30.2 podzolic soil B2 80-115 2.18 3.6 0.5 10.2 39.4 7.7 9.7 28.9 Soils on till deposits are characterized by finer texture. The greater content of sand in the topsoil of some urban soils is due to sand applied to¬ gether with thawing salts. The degree of disturbance of the soil profile and partly the age of terri¬ tory predetermine the soil stoniness and the content of carbonates. In more disturbed soils and urbanozems of squares, boulevards, lawns, and residential areas, the stoniness and content of carbonates typically correlate with the amount of construction and other lime-containing wastes. Abundance of stones or their shallow occurrence decreases the “useful” volume of soil and reserves of water and nutrients and lowers the soil fertility. In the center of Moscow, the stoniness of soils is relatively high (4 to 6% stones greater than 10 mm) and increases downwards. The chemical compo¬ sition of stony material, specifically its toxicity, is the important factor of chemical pollution of ecosystems.
Depth, сш Dcplli, cm residential area Depth, cm Particlc-sizc fractions: fine clay ( < 0,001 mm ) clay (0,001-0,01 mm) — - — silt (0,01-0,05 mm) — — . sand (>0,05 mm) Fig. 3.10. Partide-size composition of urban soils. For urban soils the amount of waste materials deposited on the soil sur¬ face is an important property. It characterizes to what extent the soil surface is excluded from the biotic cycling and/or affected by toxic compounds. This part of the soil can be considered as ballast. Bulk density of soils depends on their texture, structure, and oiganic matter content. Relatively loose soils with good structure and high porosity have lower bulk density. The bulk density characterizes the total pore vol¬ ume, the capacity of soil to accumulate water available for plants and simul¬ taneously to maintain a certain air content. It strongly affects water uptake, gas exchange between soil and the atmosphere, development of plant root systems, and the intensity of microbiological processes. The optimal bulk density for most soils ranges between 1.0 and 1.2 g/cm3. For urban soils it is often greater than 1.4 to 1.6 g/cm3.
The data obtained attest that soils of urbanized areas are subject to sig¬ nificant compaction. The bulk density widely varies in urban soils (Table 3.10, Fig. 3.11). Soils of residential areas — the most strongly affected by humans — have the highest compaction of the surface layer. Table 3.10. Moisture content, compaction, and hardness of soils in the Southwestern administrative district of Moscow Pit no. Soil Functional zone Depth, cm Moisture content, % Bulk density, g/cmJ 25. Soddy- Forest-park 0-5 26.92 1.10 podzolic 20-25 9.83 1.56 soil 45-50 3.42 1.46 65-70 3.24 1.51 105-110 8.45 1.61 10. Urbanozem Park 0-5 13.38 1.21 20-25 11.31 1.55 45-50 9.63 1.69 21. Culturozem Paik 0-5 22.16 1.04 20-25 11.90 1.31 70-75 6.25 141 60. Urbanozem Park 0-5 23.12 0.85 15-20 7.91 1.31 50-55 25.93 0.97 70. Urbanozem Square 0-5 45.94 0.74 15-20 16.21 1.15 65. Urbanozem Boulevard 0-5 22.12 1.20 15-20 19.62 1.16 13. Urbanozem Residential area 0-5 30.42 0.84 30-35 7.13 1.47 90-95 7.61 1.66 17. Urbanozem Residential area 0-5 16.50 1.22 20-25 14.93 1.32 60-65 8.32 1.23 23. Urbanozem Residential area 0-5 9.86 1.23 15-20 12.47 1.43 45-50 10.99 1.60 100-105 11.42 1.48 The bulk density changes from 0.74 to 1.47 g/cm1 in soils of lawns, yards, squares, boulevards, and parks. Such a variation depends on the state of tree and grass layers as well as on the “pressure” of the city. Low bulk density (<1.2 g/cm3) is usually noticed on lawns with a well-expressed soddy horizon. At the same sites, on strongly compacted and trampled patches, it
approaches 1.47 g/cm3. The highest bulk density is found on a children play¬ ground in yard (1.85 g/cm3). In soils of forest-paiks, the layer of 0 to 5 an is the loosest (0.9—1.1 g/cm3) while, the bulk density increases to 1.5-1.7 g/cm3 downwards. In disturbed soils, the downward change in the bulk density is spasmodic. This is caused by the presence of different amounts of construc¬ tion and household wastes. Compaction of the rooting layer is the basic process of physical deg¬ radation of soil that increases the bulk density in the topsoil. As a rule, urban soils are strongly compacted from the surface. It is likely that the strong com¬ paction and pollution of the surface layer are responsible for the specific de¬ velopment of plant rooting systems. This is when branching of roots begins not in the upper part of the profile (as it occurs under natural conditions) but at a certain depth (5 to 10 cm). 20 \ a> 20 ’ \ 7 ’ ' " \ b. 20 40 1 40 ^ 40 60 1 60 \ 60 N0 I 80 I 80 KM) 100 100 Depth cm Depth cm Depth cm Urbanophytocoenoses: a. forest-parks b. parks c. squares and boulevards d. lawns and flowerbeds e. residential area Fig. 3.11. Bulk density in urban soils under different types of urban phytocoenoses.
The lower limit of compaction hindering the root development is 1.4 g/cm3 for loamy soils and 1.5 g/cm3 for sandy soils The bulk density increased to 1.7 g/cm3 in sites with intensive traffic, while this value could be 0.8 to 0.9 g/cm3 in filled soils strongly improved with oiganic matter (Zemlyanitskiy et al., 1962). Zelikov (1964) showed that the ratio between loose and compact plots predetermined the state of conifer¬ ous stands. So, if a share of plots with a bulk density higher than 1.1 g/cm3 was greater than 30%, the tops of most pine trees suffered from drying. Gradual compaction changed the structure of soil horizons inducing the for¬ mation of coarse platy peds (Rokhmistrov and Ivanov, 1985). In addition, it was established that on lawns the rupture resistance of com¬ pacted soil with thinning and poor growth of grasses was 40 to 45 kg/cm2. For the normal growth of grasses, this value has to be two times lower (Abramashvili, 1985). Porosity is one of the most important soil properties that predetermines air and water regime. The size of pores controls the water content in soil, its permeability, and the height of capillary' rise. Soils of forest-parks, gardens, and boulevards are almost not com¬ pacted, so that their porosity varies between 45 and 75 vol %. Soil compac¬ tion decreases the porosity to 25-45 vol %. This seriously changes the water and air regimes of soils. As noted by Short et al. (1986), the average volume of pores in surface horizons of urban soils was 36.6% compared to 50% in natural soils in the state of Washington. For soils of Moscow center, the total porosity calculated by the density of soil solids is 40 to 45 vol % (Table 3.11). Typically, and contrary to natu¬ ral soils, the porosity is minimal in upper horizons of soils and increases downwards. In areas subject to a greater recreational impact, the porosity' is below 30%. It is 60% in fenced yards on improved soil. Water retention capacity and air capacity of soils are closely linked to the porosity. Deterioration of water holding capacity results in less accumula¬ tion of water in soil. The water defficiency is especially noticeable in summer, when water retention capacity makes up only 14% of that on compacted plots. Strong soil compaction in the rooting layer creates nearly anaerobic conditions, especially during continuous rains in spring and fall {Bridges, 1989; Kharaishvili, 1980; etc.). These conditions strongly complicate the
growth of fine (active) roots of trees and herbs and impede natural regenera¬ tion. Therefore, the mass of roots in compacted soils is 2.5 to 3 times lower that in noncompacted ones. Forest litter protects the soil. Its presence pro¬ vides minimal folding resistance of 4.1 to 6.9 kg/cm2 (Kucheryavy, 1981). Turf also prevents soil compaction. However, when folding resistance ex¬ ceeds 50 kg/cm2, grasses gradually disappear and a turf layer is destroyed. Table 3.11. Physical properties of urbanozems in Moscow Pit no. Func tional Horizon Depth, Hygro¬ scopic Density о soil solids, Bulk denaty, Pore vohane, Stoniness, watei weight percentage Specific surface. zone cm water, % g/cm3 g/cm3 % >1 mm >10 mm m2/g Sandy and loamy-sandy flat glaciolfluvial plain 4g- Ulh 0-27 3.20 2.57 1.17 50.9 60.0 16.6 54 Square U2 27-42 1.74 2.66 1.26 n/d 20.6 0.9 38 35g. Ulh 0-15 2.47 2.45 1.20 61.2 16.9 0.8 53 Lawn U3 20-27 0.66 2.67 1.17 56.2 29.4 3.6 8 U4 27-65 1.97 2.64 1.17 n/d 36.4 6.0 21 36g. Ulh 0-29 1.26 2.64 1.38 52.7 19.9 3.4 15 Residential U2 29-45 1.87 2.66 1.25 n/d 34.6 3.4 21 area U3 45-80 1.84 2.65 n/d n/d 26.1 2.2 19 Ancient sandy and loamy-sandy alluvium of the river terrace 33g. Ulh 0-15 1.09 2.73 1.25 60.4 22.0 2.8 6 Square U2 15-68 1.13 2.66 n/d 48.1 22.9 5.0 9 U3 68-81 0.49 2.70 n/d n/d 7.0 1.9 11 U4 81-120 2.15 2.65 n/d n/d 17.5 4.6 16 37g. A 0-10 1.04 2.57 1.39 45.9 8.1 2.0 10 Square, Layer 1 10-34 0.38 2.79 n/d 60.2 9.7 0.8 6 Replantoze Layer 3 34-65 n/d n/d n/d n/d 14.4 1.1 n/d Layer 4 65-80 n/d n/d n/d n/d 15.7 8.3 n/d 31g- Ulh 0-6 1.94 2.67 1.34 29.8 46.3 35.4 34 Square U2 6-65 1.88 2 60 1.28 48.5 31.4 5.2 6 32g. Ulh 0-8 2.75 251 1.47 47.4 5.8 0.0 64 Square. U2 8-26 2.68 1.95 1.32 24.6 0.0 0.0 62 U3 26-70 1.36 2.61 1.38 47.1 22.4 6.5 14 Note: n/d is not determined. Density of soil solids depends on the chemical and mineralogical com¬ position. It is determined by the average density of compounds constituting a particular soil and by their relative content. The density of soil solids ranges from 2.0 to 2.8 g/cm3 (Table 3.11).
Water movement. The ability of urban soils to absorb and transfer water entering their surface is an important characteristic. Water permeability and the rate of infiltration are expressed as millimeters of water column per unit time (minutes). Its value and character strongly vary with the degree of stoniness, porosity, and moisture content, and with chemical composition of soils. The presence of stones, voids, and cracks in a soil is also very essential. Urban soils are characterized by through or mosaic infiltration due to voids in the soil profile resulting from construction and household wastes. There is a relationship between the soil bulk density and the rate of infiltration. So, for example, in the undisturbed topsoil, the rate of infiltration is by 60% greater than that in a moderately trampled plot and by four times greater that in a strongly trampled plot (Amirov et al., 1982). Compacted soils of pedestrian paths have a higher bulk density and, hence, worse water-physical properties. So, rates of infiltration measured at neighboring patches of paths and lawns were essentially different (Table 3.12) The intensity of gas exchange between urban soils and the atmosphere exerts a strong effect on the urban environment and health of population. The com¬ position of soil air is also important. It depends on the gas influx from the at¬ mosphere and fluxes of gases within the soil. The other factors that affect the composition of soil air are sealing with artificial covering and leakage of natural gas from municipal communications. Table 3.12. The rate of infiltration and the density of urbanozems in a public garden near the Ivanovskiy Cloister Location Density, g/cm3 Rate of infiltration, mm/min Path 1.42 0.8 Uncompacted plot 1.30 3.5 For example, asphalt pavements almost completely seal the soil. One of the adverse consequences of slow'er gas exchange is the decreased influx of oxygen. So, the coefficient of oxygen diffusion lowers from 3 .8 x 10': cm2/sec on open sites to 5 x 10'5 cm2/sec under asphalt pavement. The low coefficient of diffusion and the absence of other sources of oxygen make its amount in¬ sufficient for the life of microorganisms and plant roots. However, oxygen can enter the soil beneath road asphalt from neighboring patches Further¬
more, there is a direct relationship between the oxygen content in the center of the road and its width. The gas composition of soils is also affected by gas leakage from mu¬ nicipal gas communications. In many Western European countries, this sometimes causes a decline of urban trees and shrubs as reported in detail in the monograph of Hocks (1972). It also likely occurs in our cities. However, this phenomenon is not sufficiently studied. After gas leakage is eliminated, the number and composition of micro¬ organisms and the composition of soil gas phase change essentially. It takes several months to one year to restore the original composition of the gas phase in soil. As a result of gas leakage, some inorganic reducers (Fe2+, Mn21", and S2') and organic acids can appear in soils. The composition of soil air in urban phytocenoses can be controlled through specially developed methods, including the establishment of ventilation canals and soil compressing within the rooting zone. The bulk of data on changes in water and physical properties in urban soils is insufficient; though available data attest to soil deterioration practi¬ cally at any level of human effect. Thus, urban conditions change physicomechanical properties of soils. Urban soils are compacted and very poorly structured. This is due to the fol¬ lowing changes. • The majority of urban soils is formed on the material of natural soddy-podzolic soils displaced from sites of their natural occurrence. This equally deforms their structure and arrangement of strata. • Soils experience the lack of organic matter—the basic aggregating component—that weakens the water-stable structure, diminishes the space of micropores, and, respectively, results in strong compaction. • Strongly compacted soils are characterized by disturbed cycles of wetting and drying compared to undisturbed soils. Wet, strongly com¬ pacted soils become dry more slowly than natural soils. In addition, they become wet slower when dry. As a result, the amount of available water in soil profiles decreases. Formation of a water-repellent crust on the bare surface of soil is promoted by several factors (Craul, 1992): surface compaction by trampling and pressure and the absence of loosening and protective influence of roots and plants. As a re¬ sult. the input of organic matter to soil decreases. The other factor, which was yet
poorly studied, is the effect of gasoline-based aerosols being deposited от the soil surface from the atmosphere. After interaction with soil, they can produce water- repellent structures, which finally form the surface crust. Since the occurrence of urban soils is restricted to a certain area, they are surrounded by “sealed” spaces and different barriers: walls, paved streets, founda¬ tions of buildings, etc. All these factors, including crust formation on the soil sur¬ face, strong compaction, and dumping with nonporous materials, deteriorate con¬ ditions for water exchange and movement throughout the soil profile. 3.2.3. Chemical Properties of Soils Most of the toxic compounds emitted into the urban environment concentrate on the soil surface. Their gradual deposition changes the physicochemical and chemical properties of soils and substrates. Owing to that, urban soils signifi¬ cantly differ in chemical properties from their natural analogues (Table 3.13). Acidity of urban soils varies greatly throughout the rooting layer. Nonethe¬ less, soils with a neutral and slightly alkaline reaction dominate (Gantimurvv, 1966; Nikodemus and Ramarm, 1984; Lepneva et al1987, 1990). The reaction of urban soils is typically more alkaline compared to natural soils (Blume. 1989; Obukhov et al., 1989, 1990a,b; Hollis^ 1991). Table 3.13. Properties of the topsoils of urbanozems and soddy-podzolic soils in the Moscow region Properties of topsoil Urbanozem Soddy-podzolic soil Corg, % 2-7 1-2 pHwata up to 8 45-6.5 Ca~, cM/kg of soil 5-100 5-10 Mg”, cM/kg of soil up to 30 2-3 С EC, cM/kg up to 30 10-12 Base saturation, % up to 100 60-70 P2O5, mg/100 g of soil 5-150 5-10 K2O, mg/100 g of soil 2-60 7-15 SO:,2", mg/100 g up to 220 0 СГ mg/100 g up to 40 0 NO3', mg/100 g 12-15 0 The high alkalinity of urban soils is attributed to the predominant accumula¬ tion of calcium and sodium chlorides and other salts used for snow tliawing on roads and pavements. They enter the soil with surface runoff. Another reason is
calcium release from fragments of construction waste, cement, brick, and other al¬ kaline-based compounds (Gcmtimurov, 1966; Obukhov etal., 1989; and others). The high alkalinity of urban soils is also due to the intensive deposition of dust, which contains calcium and magnesium carbonates. These compounds originate from highways and lime-based cement. The latter is easily weatherable and releases Ca to the soil. Bicarbonates are formed in soils under the action of precipitation when it is high in dissolved carbonic acid. These compounds are ca¬ pable to shift the soil reaction towards stronger alkalinity. Urbanozems and strongly disturbed natural soils are always more alkaline compared to soddy-podzolic soils of forest-paiks that have acid and slightly acid reaction. In upper soil horizons in parks and forest-paiks, pH widely ranges from slightly acid to slightly alkaline (pH^ is 5.8 to 7.5). In most cases, the pH de¬ creases to 4.8 to 6.5 downward the soil profile. In topsoils on lawns, squares, boulevards, fenced yards, and recreational areas, the pH*^ ranges from 7.3 to 8.3 (even up to 8.9 under asphalt). Most alkaline are soils inside the Boulevard Ring (pH 8.6 to 8.9) (Fig. 12a). As known, neutral pH promotes the development of most of the plants and microorganisms, and also immobilizes heavy metals. However, further alkaliza- tion may result in binding of some nutrients and microelements. In addition, at pH 8 to 9, the soil becomes unsuitable for plant growth. Thus, the human-made and strongly disturbed natural soils in Moscow are typically more alkaline than natural undisturbed urban soils and natural ones in rural areas (Tables 3.14-3.16). Urban soils also have specific proportions of exchangeable bases in the cation exchange complex. Soddy-podzolic soils are dominated by hydrogen and aluminum and are low in calcium and magnesium (10 to 15 cM/kg of soil totally). In contrast, in urbanozems, calcium constitutes up to 70% of the CEC, while the total CEC is more than 30 cM/kg of soil. Soils of all studied habitats contain significant amounts of exchangeable calcium (from 5 to 50 cM/kg of soil). Surface layers of soil in squares, boulevards, lawns, fenced yards, and residential areas are the richest in ex¬ changeable Ca (20 to 50 cM/kg and more). Its content is similar to that in high humus soils (Tables 3.14 and 3.15). In parks and forest-parks, its amount is 15 to 20 cM/kg in the topsoil (that is similar to its content in soddy-podzolic soils) and 5 to 10 cM/kg in subsurface horizons. It typically decreases downwards. In urbanozems, the content of exchangeable Ca di¬ rectly relates to the amount of Ca-containing inclusions.
Table 3.14. Chemical properties of urban soils on river terraces Note: n/d is not determined.
Table 3.15. Chemical properties of urban soils on hilly gently undulating plain Note: n/d is not determined.
Table 3.16. Chemical properties of urbanozems in the Moscow downtown Pit no. Functional zone Depth, cm pHwater Available, mg/kg Corg, % k2o P2Os Glaciofluvial plain in the Moscow downtown 24g. 0-16 8.0 228 291 2.50 Residential area 16-62 8.2 163 348 1.08 25& 1-10 8.2 188 348 3.53 Lawn 10-30 8.5 252 406 2.84 30-70 8.1 n/d n/d 0.92 26& 0-12 8.0 316 406 6.16 Lawn 12-27 8.6 232 212 1.87 27-60 8.9 n/d n/d 1.73 27& 0-4 8.7 132 186 0.91 Residential 4-15 8.2 188 134 0.28 area 15-42 9.1 196 248 0.86 28& 0-17 8.2 268 479 2.55 Residential 17-36 7.8 172 422 4.29 area 36-60 8.2 n/d n/d 3.33 34g. 0-27 7.5 265 296 1.99 Square 27—42 8.2 99 207 4.12 35& 0-15 8.1 248 146 4.7 Lawn 20-27 8.6 58 91 0.56 27-65 8.1 170 183 3.52 36& 0-29 8.4 n/d 251 2.22 Residential 29-45 8.5 n/d 250 1.97 area 45-80 8.3 n/d 305 1.56 River terraces in the Moscow downtown 13& 0-3 7.6 236 260 2.58 Square 3-22 7.0 1068 137 1.16 22-39 7.3 1048 81 0.56 39-42 8.7 n/d n/d 0.23 42-60 87 n/d n/d 0.83 60-77 8.2 n/d n/d 0.88 33& 0-13 7.9 282 195 2.04 Square 13-68 8.2 148 172 1.37 68-81 7.7 88 249 0.43 81-120 7.3 289 373 1.59 37g. 0-10 8.0 122 109 1.07 Square. 10-34 8.2 65 85 0.24 Replantozem 34-65 8.4 109 211 0.26 65-80 8.4 85 227 0.24 Note: n/d is nol determined.
The content of exchangeable Mg is much lower (0.5 to 5.0 cM/kg of soil). However, its distribution throughout soils of different habitats has a similar pattern to that of Ca. Its amount is lower in forests and forest-parks and is higher in urba¬ nozems. A relatively significant content of exchangeable Ca and Mg in soils in the park of Leo Tolstoy's museum-estate (Khamovniki) is likely attributable to the good management of these soils. Literature data confirm the high base saturation to be the typical feature of uiban soils. In many cases, it exceeds 80-95% and readies 100% (Bashirova, 1970; Blume et al., 1978). It is typically 60% and less in soils of most of the parks and city forests. The composition of exchangeable bases is dominated by Ca (up to 70%) and Mg (up to 30%) (Konecka-Betley et al., 1985; Lepneva et al., 1987; Bridges, 1989). The base saturation within the soil profile of soddy-podzolic soils in Moscow urban forest-parks (Kuntsevo and Vorob'evy Gory) varies from 60 to 85%. In soils of lawns situated along roads, the content of exchangeable sodium sometimes reaches 5 to 10% of the sum of exchangeable bases. According to Lepneva and Obukhov (1990), the application of deicing salts on roads and pave¬ ments contaminates with sodium the mehwater running to the lawns. Thus, the content of Na+ is up to 115 to 130 mg/1 and that of СГ is up to 75-140 mg/1. These contents are two times higher than those found in city parks. Their amount signifi¬ cantly decreases as a result of spring, summer, and fell precipitation. Salinization can adversely affect the plant development. The research con¬ ducted by Nikiforova and Lazukova (1995) in the eastern part of the city on areas along highways and local roads showed that soils had a relatively high amount of adsorbed sodium. This comprised up to 5 to 15% from CEC, so these soils were slightly and moderately solonetzic (alkaline). Plant nutrition status of urban soils attests to their good provision with nu¬ trients. However, nutrients (N, P, and K) are irregularly distributed in urban soils. Many researchers noted the strong enrichment of layers of tipped material and slightly disturbed soils with nitrogen, phosphorus, and potassium compared to natural soils (Zemlyanitsldy et al, 1962; Bashirova, 1970; Nikodemus and Ra- mann, 1984, Lepneva etal., 1987; and others). In acid soils, mobile forms of potassium and phosphorus are determined in IN NaCl and 0.2N HCI, respectively; in calcareous soils, mobile forms of potas¬ sium and phosphorus are determined in 0.2N (NH^COj, and 1% K2C03, re¬ spectively. In human-affected soils of the Kadriorg park in Tallinn (Estonia), the
content of plant-available potassium (K20) and phosphorus (P2O5) varies from 5.0 to 500 and from 4.0 to 125 mg/100 g of soil, respectively (Payu et al, 1980). In Riga, surface soil horizons contained potassium and phospho¬ rus in the amount ranging from 1 to 90 and from 1 to 180 mg/100 g of soil, respectively (Nikodemus and Ramann, 1984). Soils of Moscow consisting of tipped material (Zemlyanitskiy et al., 1962) were highly provided with plant available phosphorus (100 to 200 mg/100 g of soil and more). The data on their provision with plant-available potassium are contradictory. Sometimes only traces of potassium are detected. However, its content may reach 40 mg/100 g. In most cases, such an enrichment with nutrients is attributed to household and construction wastes deposited on urban soils. In most of the samples of urban soils in Moscow, the content of available P and К exceeds the need of plants for these nutrients (Table 3.14-3 .16). Provision of urban soils with nutrients can be considered as elevated, high, and very high. The content of mobile phosphorus and potassium ranges from 5 to 150 and from 2 to 100 mg/100 g of soil, respectively. Composition and content of organic matter The content of organic matter in urban soils is quite variable and depends on the nature of original substratum and management pattern: application of or¬ ganic and mineral fertilizers etc. Typically, the content of organic matter in urban soils often exceeds that in background soils. In old soils of squares, parks, and gardens, the humus content reaches the maximum (8 to 12%), while it is 4 to 6% on an average in Moscow and other cities within the forest zone (.Zemlyanitskiy et al., 1962; Bashimva, 1970; Nik¬ odemus and Ramann, \9%4, Lepneva et al, 1987; and others). It slightly, often ir¬ regularly, d.xreases downward the soil profile. As noted by Zemlyanitskiy et al. (1962), sometimes long-used soils acquired morphological features of chernozems as those in tre Aleksandrovkiy Garden of Moscow. Its highest amounts were found in disturbed and newly formed soil layers on lawns, squares, boulevards (5 to 11%), and residential areas (3 to 7%). In parks and forest-parks, natural humus horizons contained 1 to 2% oiganic carbon (2 to 3.5% humus), while its content in human-made horizons was 2 to 5% (4 to 9% humus). In parks and forest-parks, the humus content of soils strongly decreased downward the profile to tenths of percents or zero (Table 3.17; Fig. 3.12b). Urbanozems and culturozems have a deep humus-accumulative profile.
The humus content can remain significant (1 to 2% organic C) even at the depth of 50 to 70 cm and deeper. Depth, tin b о 10 20 30 40 5(1 60 70 80 90 Depth cm parks Depth, lawns cm 1 2 3 4 % 0 cm I 2 3 4 % 0 s 10 10 / 20 20 / 30 \ 30 1 40 \ 40 I 50 \ 50 / 60 У 60 / 70 / 70 / 80 / 80 * 9<l ' 90 Depth, residential area 6 % parks Depth, cm lawns Depth, cm residential area Fig. 3.12. Changes in chemical properties of urban soils with different land use (a) pHwater, (b) Corg.
Just a few studies on composition and properties of the organic matter of urban soils are available. A team of authors from the University of Kiel (Germany) studied the composition of organic matter in soils and litters of different urban soils (Beyer et al., 1995). When compared to natural soils with similar distribution of organic matter along the profile, the organic mat¬ ter of all urban soils was characterized by a low proportion of fulvic acids, while the fraction of hydrophobic lipids was very low. Apparently, microor¬ ganisms can destroy organic compounds that constitute the mentioned frac¬ tions and which are so abundant in natural soils. These changes can be due to a high pH of urban soils. The ability of microbial population to reduce the fractions of hydrophobic lipids and fulvic acids likely means that they prefer to consume these compounds. This can be useful, since intensive traffic is a constant source of pollution of urban soils with oil and gasoline. On the other hand, small proportions of lipids increase the water retention capacity and, hence, the heat capacity of soils. Properties of humus-like compounds formed during decomposition of composts made from urban garbage and their relation to humus compounds of natural background soils are described in many of papers (Gomez et al., 1987; Wtis et al., 1989). At the same time, there is some disagreement on the elementary composition of these compound. One can notice a lower biological stability' of humus compounds in the compost. This is attributed to the high share of proteins, lower molecular weight, and weaker bonds with the mineral part, particularly with Fe and Cu. It is thought that these organic acids are the early stage of formation of humus compounds. In young urban soils, fulvic acids and free components of compost (proteins and polysaccharides) dominate the organic matter. In old soils, pro¬ teins and polysaccharides are included in the humus matrix that likely dimin¬ ishes their availability for microorganisms. Thus, it is possible to control hu¬ mification in urban soils. The composition of humus in urban soils of Moscow differs from that in natural soils. The analysis of its group and fractional composition (Table 3.17) revealed domination of humic acids in some surface layers and hori¬ zons. Undisturbed soddy-podzolic soils and disturbed to some degree were characterized by a downward decrease in this ratio. The Cha-to-Cfa ratio was typically 0.6 to 0.9 (profiles 4, 10, and 25). In urbanozems (profiles 7, 67: and 72) on residential areas, squares, yards, boulevards, and parks, the com¬ position of humus remained humic or fiilvic-humic (Cha-to-Cfa ratio is 1.0-
Table 3.17. Composition of humus (percentage of total carbon) Pit no. Functional Horizon Depth, С total, Fractions of humic acids Sum zone. Soil cm % 1 2 3 25. A 0-10 2.69 12.1 8.0 7.1 27.2 Forest-park (Fili). AE1 10-30 0.59 22.9 17.0 8.3 48.2 Sodd)>- podzolic El 30-58 0.17 17.1 6.5 14.7 38.3 B1 58-75 0.17 11.2 4.7 8.8 24.7 B2 75-122 0.14 10.7 2.1 4.3 17.1 19. Forest park A 0-24 1.37 12.2 13.9 6.0 32.1 (Vorob'evy Gory) AE1 24-33 0.26 10.4 9.6 22.3 42.3 Soddy-podzolic E1B 33-54 0.18 10.0 8.9 18.9 37.8 B1 54-104 0.13 9.2 12.3 14.6 36.1 10. Park. Ulha2 0-10 3.46 11.7 12.1 7.0 30.8 Urbanozem. 20-30 1.41 13.1 8.7 9.2 31.0 U2ihn2 40 63 1.05 4.9 9.6 5.4 19.9 B1 63-71 0.43 10.5 19.3 9.1 38.9 B2 71-110 0.27 7.8 10.0 4.1 21.9 12. Boulevard. Ulha2 0-15 6.30 7.6 15.6 31.1 54.3 Urbanozem. U2ha2 15-30 6.49 4.9 5.1 6.5 16.5 30-52 2.72 6.3 5.2 14.3 25.8 13. Residential Ulha2 0-10 2.85 8.8 9.2 5.5 23.5 area. 20-30 1.81 7.4 20.1 6.5 34.0 Urbanozem. U2a2 30-60 1.12 16.4 14.7 10.3 41.4 U3a2 60-115 0.45 4.2 8.4 11.6 24.2 17 Residential Ulha2 0-10 4.66 9.3 10.4 10.9 30.6 area. U2a2 35-50 0.99 13.0 23.7 11.1 47.8 Urbanozem 90-130 1.02 10.2 15.6 10.9 36.7 1. Residential area. Ula4 0-40 1.42 8.4 12.9 10.6 31.9 Urbanozem. U2al 40-72 1.05 15.7 13.6 14.0 43.3 67 Playground. Ulh 0-14 2.79 10.4 9.3 20.4 40.1 Urbanozem. U2a4 14-40 1.64 6.1 11.0 15.2 32.3 40-60 1.79 8.9 14.5 15.6 39.0 21 Park. Ulhal 0-16 2.31 15.0 3.8 11.1 29.9 Culturozem. U2ih 16-44 0.34 18.2 9.7 12.4 40.3 U3 44-90 0.10 25.0 11.0 3.0 39.0 4 Park. Ulh 0-14 2.42 9.6 11.7 9.8 31.1 Soddv-urbo- E1B 14-48 0.28 20.4 6.4 12.5 39.3 podzolic. Bl 48-80 0.25 11.2 7.2 6.0 24.4 Note', n/d is not determined.
Fractions of fulvic acids Sum Cha/Cfa Unhydrolizable la 1 2 3 residue, % 7.9 8.4 8.3 10.5 35.1 0.78 37.7 10.5 1.2 20.7 2.5 34.9 1.38 16.9 17.1 5.3 10.0 9.4 41.8 0.92 19.9 7.1 0.0 12.4 1.5 21.0 1.17 54.3 17.9 7.1 0.7 5.7 31.4 0.55 51.5 13.4 22.0 1.0 11.0 47.4 0.68 20.5 17.3 2.7 17.7 1.5 39.2 1.08 18.5 18.9 5.0 9.4 5.6 38.9 0,97 23.3 20.0 10.8 11.5 5.4 47.7 0.76 16.2 5.8 5.2 6.3 8.0 25.3 1.21 43.9 13.5 7.5 13.5 0.4 34.5 0.90 34.5 10.5 7.5 2.1 3.1 23.2 0.86 56.9 14.4 8.1 13.3 5.4 41.2 0.94 19.9 30.7 2.7 21.9 4.8 60.1 0.36 18.0 5.9 8.6 12.5 4.9 31.9 1.70 13.8 6.2 0.5 4.5 3.2 14.4 1.15 69.1 2.9 n/d 13.6 1.5 18.0 1.43 56.2 9.2 9.1 16.2 8.7 43.2 0.54 33.3 12.1 7.2 7.5 7.1 33.9 1.00 32.1 13.5 3.9 19.0 6.5 42.9 0.97 15.7 11.6 n/d 21.3 n/d 32.9 0.73 42.9 5.7 7.6 12.5 5.8 31.6 0.97 37.8 13.1 6.1 9.1 6.8 35.1 1.27 17.1 4.4 4.8 20.8 11.9 41.9 0.88 21.4 9.0 3.3 9.7 2.3 21.3 1.31 43.8 19.3 6.6 7.3 6.2 39.4 1.10 17.3 9.0 0.7 21.5 7.5 38.7 1.04 21.2 5.5 1.2 8.5 7.9 23.1 1.39 44.6 4.5 1.1 10.6 6.7 22.9 1.71 38.1 8.3 12.9 17.4 8.8 47.4 0.63 22.7 16.8 11.2 10.9 6.5 45.4 0.89 14.3 10.0 13.0 14.0 13.0 50.0 0.78 11.0 8.4 13.7 4.2 2.9 19.2 1.06 39.7 15.7 2.1 27.9 3.2 48.9 0.80 11.8 17.2 3.2 25.2 20.4 66.0 0.37 9.6
1.7). The group of humic acids contained a small percentage of free humic acids in all samples (typically less than 15 to 20%). The proportion of the 2d and 3d fractions was greater. This was especially typical for soils (profiles 4, and 67) on squares, boulevards, and residential areas, where these fractions dominated throughout the soil profile. The group of fulvic acids was also featured by the high content of the 2d fraction bound with Ca (up to 15 to 20%). The proportion of other frac¬ tions was almost the same, although being much lower (usually up to 10%) — profile 4, 67, and 72. Natural soddy-podzolic soils in forest-parks were dominated by 1 st a and 1 st fractions of fulvic acids (profile 19). The studied soils had a low content of nonhydrolyzable residue (20 to 40% of the total carbon content) that characterized how tightly the humus compounds were bound with the mineral part of soil. Its content mostly de¬ creased downwards. Thus, urbanozems approach Ca-humus soils by some properties except the high content of organic carbon. They are also characterized by the Cha- to-Cfa ratio greater than 1.0. The content of free HA and FA and of nonhy¬ drolyzable residue is low, while fractions bound with Ca dominate. Data on soils of Yaroslavl with similar background conditions support this regularity' (Rokhmistrov and Ivanova, 1985). Bulk reserves of nitrogen in soils are low and almost do not vary (0.03 to 0.20%) tliroughout the city (Tables 3 14 and 3.15). Their higher content is noted in surface layers of some strongly disturbed soddy-podzolic soils (0.40%), urbanozems (0.3 to 0.6%), and culturozems (0.3%). The nitrogen content has “peaks" at the depth of 52 to 80 cm (0.31% nitrogen in pit 72) in buried humus horizons. 3.2.4. Pollution of Urban Soils Beginning in the 1960s and up to the present time, urban ecologists and soil scientists are very much interested in the problem of pollution of urban soils. Of 120 cities of Russia, 80% are characterized by contents of lead and other heavy metals essentially exceeding estimated allowable concentrations (EAC). It is assumed that more than 10 million people contact with soils on average containing lead in an amount greater than the EAC. The content of lead typically varies from 30 to 150 mg/kg, with an average of 100 mg/kg.
To a significant degree these parameters arc detennanod by the stance of pollution and the distance from it, and by the amauriL and anjmsakn of emission. The distribution of heavy metals is specific fir ooy cfly aid for any of its patches. Their distribution along the soil smface is «ЬнийиН by peculiarities of pollution source, weather pattern (wmd rase). guochcmical factors, vegetation, land use, and landforms. The severity of chemical pollution of soils with heavy metals depends an the content of their bulk and mobile forms, which, m turn is codroOd by some physicochemical properties and texture of sak. In Russia, the rale of soil pollution is determined as a ratio of the contort of a poUiflant in sod to its MAC (maximum allowable concentration), EAC (estimated allowable con¬ centrations, Table 3.19), and background values (Table 3.18, GOST(“Slaie Standards”) 17.4.3.06-86, Criteria for Estimation..., 1992; The Order of Determination..., 1993; GN (“Hygienic Standards”)2.1.7.020-94). Table 3.18. Content of heavy metals and arsenic in badkgpnmd mgfcg Soil 7a I Cd I Pb 1 He | Cm II Ca В Рй II As Soddy-podzolic soil (sandy and loamy sandy) 28 0.05 6 0.05 Ж 3 6 25 Soddy-podzolic soil (loamy and clay) 45 0.12 15 0.10 15 10 * 45 | Gray forest soil 60 020 16 0.15 US 12 35 ш>Я Chernozem 68 0.24 20 020 25 15 45 7-» Chestnut soil 54 0.16 16 0,15 20) 11 35 2 ; Note: n/d is not determined. Table 3.19. Classes of soil pollution with heavy metals, mg%g PotataA Level of soil pollution Pb 1 Cd Zn 1 c. 1 ш 1st class of toxicity 2ddHrf fondly Estimated allowable bulk concentrations 32-130 0.5-2.0 55-220 ЗЭ-Ш m-m Low 130-150 2.0-3.0 220-300 m-15® ГО-15© Moderate 150-500 3.0-5.0 300-500 13B-25® 1ЭЭ-ЗШ High 500-1000 5.0-10.0 500-1000 ЗГО-ШВ Extremely high >1000 >10.0 >1000 >зш >Ш) Source: Hygenic Standarts 2.]. 7.020-94; Temporary m ■■■—мЛийми* В 990..
Soil pollution results from the accumulation of pollutants of nonsoil ori¬ gin and is among the main features of urban pedogenesis. Contaminating material can be solid (paper, glass, plastic, and solid deposition from the at¬ mosphere), liquid (polluted atmospheric precipitation and surface runoff, in¬ dustrial waste, canalization discharge, etc.), and gaseous (methane, inciner¬ ating gases, gases from buried waste, etc.). Recently, the major importance has been gained by the problem, of soil pollution with human-made materials. Inclusions strongly influence all soil properties, since they restrict the area accessible for roots and suitable for mi¬ croorganisms. They also decrease the water retention capacity of soils. Cal¬ cium-containing construction waste, dust, cement fragments, and similar ma¬ terials promote soil alkalinization. In turn, toxic compounds and gases that substitute oxygen of soil air become released during decomposition of other wastes. Among many approaches to the factor differentiation of urban soils, of especial importantce is their pollution with heavy metals, radionuclides, chlororganic compounds, and other toxicants (Poltavskay, 1964; Grigoryan and Saet, 1980; Armolaitis, 1985; Saet et al., 1985; Obukhov et al., 1989; 1990a,b; Lepneva et al., 1987, 1988, 1990, Geochemistry of the Environ¬ ment, 1990; Thornton, 1991; Ecogeochemistry..., 1995; Nikiforova and Lazukova, 1995; and others). The territory of Moscow is affected by diverse sources of contamination (Fig. 3.13). Urban soils have the increased contents of heavy metals, namely, Ag, Cu, Zn, Pb, Cd, W, V, Ni, Cr, and Co in the topsoil. The high content of mo¬ bile (not only of bulk) forms of heavy metals is also dangerous (Tables 3.20 and 3.21). Presently, pollution in Moscow is mainly due to emission of industrial plants, themial pow'er stations, and motor transport; the latter is the main source of pollution. Specialists recognize more than 40 chemical compounds (many of them are toxic) in exhaust gases. The content of toxic lead is espe¬ cially high and is identified within the distance of 100 m from a highway.
communal, warehouse areas Fig. 3.13. The pattern of pollution sources in Moscow (industrial, communal, and warehouse meas). Inspections of Moscow Committee for Nature Protection established more than 100 unauthorized disposals of solid household, industrial, and con¬ struction wastes. The greatest amount of unauthorized disposals is in North¬ eastern, South, Southwestern, and Eastern administrative regions. Focuses of strong pollution are found in the Northwestern Administrative Region, in the city center, in the northern part of Izmailovo forest-park, and near Lyublino aeration fields. Here concentrations of some chemical compounds are by 20 to 30 times above their background values.
Table 3.20. Content of heavy metals in urban soils (extraction with IN HN03, mg/kg) Pit no. Functional zone. Soil Horizon Depth, cm Pollutants Cu Zh Pb Cd River terraces 25. A 0-10 5 42 15 0.3 AE1 10-30 10 12 6 0.2 Foresl-paik. El 30-58 6 4 4 n/d Soddy-podzolic B1 58-75 7 3 4 n/d B2 75-122 13 3 4 n/d B2 122-148 11 3 4 n/d 10. Ulha2 0-10 25.6 98 105 0.6 10-20 20.0 64 77 0.6 r3J\. 20-30 49.7 192 406 0.3 Urbanozem 30-40 12.1 46 37 0.3 U2ihal 40-63 16.4 48 18 0.3 B1 63-71 20.0 34 13 0.2 B2 71-110 15.5 18 5 0.1 72. Ulha2 0-15 262 1000 64 1.8 Boulevard U2ha2 15-30 88 336 160 1.0 Urbanozem 30-52 39 110 96 0.4 13. Ulha2 0-10 82 734 600 1.3 10-20 76 588 560 1.2 Residential area. 20-30 58 194 600 0.8 Urbanozem U2a2 30-60 28 58 25 0.5 U3a2 60-115 6 22 18 0.4 17. Ulha2 0-10 34 178 74 0.7 10-20 38 148 85 0.6 Residential area. 20-30 38 124 101 0.6 Urbanozem U2a2 35-50 16 16 52 0.5 90-130 21 30 37 0.5 Hilly-gently undulating plain 4. Ulh 0-14 19 84 74 0.6 E1B 14-48 15 16 9 0.3 г агк. B1 48-80 15 14 9 0.2 Sodcl\'-urbo-podzokc B2 80-115 14 18 8 0.2 23. Ulh 0-3 36 164 28 2.2 U2ihal 3-30 15 48 31 0.4 Residential area. U3 30-70 12 32 16 0.4 Urbanozem B2 70-120 100 130 74 0.6 39. Uldal 0-8 13 68 14 0.2 U2h 8-22 18 82 13 0.2 U3ha2 22-35 21 62 13 0.4 Urbanozem U4 35-55 10 28 11 0.1 Note: n/d is not determined.
Table 3.21. Content of heavy metals in urbanozems in the Moscow down¬ town (extraction with IN HNO3, mg/kg) Pit no. Func¬ tional zone Depth, cm Pollutants Pb Cu Zn Cd Fe Mn Co Ni V Glaciofluvial plain 23g. Residential 0-19 204 81 239 0.5 n/d n/d 3 5 6.69 area 27-37 167 46 216 0.4 n/d n/d 3 4 6.19 37-60 152 51 128 0.3 n/d n/d 2 4 10.9 24g. Residential area 0-16 84 39 156 0.7 n/d n/d 3 7 6.84 25g- 1-10 194 89 409 1.0 n/d n/d 2 11 9.79 Lawn 10-30 313 86 167 0.4 n/d n/d 1 7 10.0 30-70 228 131 177 0.3 n/d n/d 2 6 7.96 27g. Residential 0-4 32 20 166 0.4 n/d n/d 3 2 2.14 area 4-15 2 6 12 0.1 n/d n/d 2 1 1.44 15-42 40 26 95 0.2 n/d n/d 2 3 3.41 28g. Residential 0-17 117 75 247 1.9 n/d n/d 34 15 8.99 area 17-36 118 58 377 0.6 n/d n/d 2 9 14.2 34g. Square 0-27 110 80 375 3.2 1600 240 n/d п/d n/d 27-42 225 30 90 0.6 1500 200 n/d п/d n/d 35g. Lawn 0-15 70 30 125 0.6 1000 140 n/d n/d n^d 20-27 45 12 55 0 800 80 n/d п/d n^d 27-65 102 34 115 0.4 1200 146 n/d n/d n/d 36g. Residential 0-29 155 72 175 1.0 1600 160 n/d n/d n/d area 29-45 137 100 85 0.4 2900 200 n/d n/d n/d 45-80 212 70 85 0.2 2600 220 n/d n/d n/d River terraces 31 g. Square 0-6 215 48 180 1.0 1600 260 n/d n^d n/d 6-65 163 57 150 1.0 1800 240 n/d n^d n/d Note: n/d is not determined. Lead is the most widespread pollutant. However, its effect is accompa¬ nied by deposition of three tons of sulfur-containing compounds and of up to two tons of nitrogen-containing compounds (combined deposition is up to two tons) per square kilometer of the area of Moscow per year . The distribution of heavy metals typically does not follow the normal distribution. Their content can vary by two to three orders of magnitude,
somewhere exceeding maximum allowable concentrations (MAC) by 5 to 100 times (Obukhov et al., 1990). There can be two and more maximums in their content along the soil profile (Fig. 3.14). о 10 20 30 40 50 60 70 80 Depth, cm 50i 150| 2501 350| mg/kg 0 0,2 | 0,6 | 1,0| 1,4| mg/kg I У ■V • V ' ' У » I ' / I .1 Pb 10 20 30 40 50 60 70 80 residential area forest-park park lawn square Cd 90 90 Depth, cm Depth, cm Fig. 3.14. Heavy metal distribution in urban soils of different land-use types (extract with IN HNOj, mg/kg). The content of Pb and Zn in Moscow soils, with exception of forest- parks, is 3 to 4 times higher than their background contents (Obukhov et al., 1988, 1989, and 1990a, b). In soils of squares and residential areas of Mos¬ cow, the content of Cu is in excess of two to five times. Stronger pollution with Cd compared to background soils (by 2 to 3 times and more) is recog-
nized in soils of boulevards, lawns, and residential areas. As the center of the city is approached, the content of heavy metals in lawn soils along roads in¬ creases. As pollution becomes stronger, its spatial variability increases. The content of heavy metals is maximal in soils of lawn strips that divide the tracks (Lepneva et al., 1990). The accumulation of heavy metals in natural soils of Izmailovo and Fili parks, Vorob'evy Gory, and Kolomenskoe park- natural reserve is maximal in the layer of 0 to 5 cm. It is by 1.5 to 2 times higher than in soddy-podzolic soils of the Moscow region. According to the same authors, the significant content of heavy metals is noted for the parterre part of the Central Park for Culture and Rest; their distribution in the lower part of the profile is abnormal. This is because the park was partially estab¬ lished on the place of a city dump. Therefore, the substratum contains abun¬ dant inclusions of polluted construction debris. Increased amounts of heavy metals were reported in soils of the Luzhniki sport arena. This is the case when the accumulation of gas and dust emissions of industrial enterprises and transport is determined more by natural agents, than by authropogenic ones: the sport complex occupies the lower part of the flood plain of the Moskva River. The downtown of Moscow is located in the fluviatile landscape This makes it dependent on the input of pollutants from the elevated built-up city periphery, discharging groundwater, as well as to air stagnation in the valley In the city center, there are nearly 90 industrial enterprises comprising 20 en¬ terprises of machine and instrument industry, 10 oil refinery enterprises, 20 printing enterprises, 17 enterprises of light industry, 2 electrotechnical enter¬ prises, 3 energetic enterprises, etc. Industrial enterprises are irregularly em¬ bedded in residential areas. As a result, the center of Moscow is strongly polluted with heavy metals; and its pollution may be qualified as that of the 1st and 2nd class of toxicity by zinc, cadmium, lead, chromium, nickel, and copper This level of pollution was identified in soil, tree leaves, lawn grasses, and children sand boxes. In the downtown, the strong pollution of soils and vegetation is persistent. The way a particular patch of land was used in ancient cities, including Moscow, was changed several times, so altering the land-use pattern. This af¬ fects the properties of an accumulating substratum, including its pollution with heavy metals. Pollution with heavy metals could occur during industrial activities of the last centuries, because of bombing the buildings during wars
and their consequent reconstruction, and as a result of the installation of lead pipes. Research of the cultural layer in the ancient part of the city showed that pollution of Moscow soils has started many centuries ago (A leksandrovskaya, 1996, Aleksandrovskaya and Aleksandrovskii, 1997). Cultural layers of the 15th to 19th centuries are characterized by the noticeable accumulation of lead, arsenic, copper, and zinc. This reflects their diverse use by humans in metal working, utensils production, leather treat¬ ment, building, and other activities. So, the content of arsenic in a layer of the 17th to 19th centuries is up to 74 mg/kg, while its clarke (average content in the Earth’s crust) is 2 mg/kg. In addition, there is an intensive accumulation of copper. In cultural layers of the 15-16th centuries, the content of copper is up to 650 mg/kg (typically its content in soils of Moscow region is 3 to 20 mg/kg). The source of copper could be copper sulfate, which was widely applied, since, similar to lead, copper was easy to fuse, forge, etc. The average lead content in the Earth’s crust (13 mg/kg) is greater than that in the original soils. Wide application of lead during the 15th to 20th century has increased its content up to 450 to 900 mg/kg in layers referred to Medieval Mos¬ cow. It is sometimes up to 1321 mg/kg in layers of the 19th century (Table 3.22). Ancient pollutants often come to the surface layers during excavations. In this case, they can be mixed with the modem layers, so producing a cu¬ mulative effect, which is manifested in the gradual increase of pollution from deeper to surface layers. The eastern part of Moscow as well as its center has the most deterio¬ rated environment. These areas are most polluted with heavy metals, chloror- ganic and other toxic compounds. On one hand, these are heavily industrial¬ ized and densely populated territories; on the another hand, western winds carry here the additional amount of pollutants. Metallurgical, machinery, and polygraphical enterprises, thermal power stations, motor transport, and so on emit nearly 130 kg pollutants per inhabitant per year. The total pollution of the environment is 1.22 kg per square meter of the district area. Here the accumulation of Pb, Cu, Zn, Cr, and Cd in soils is by seven to eight times greater than the background contents of these elements (Nikiforova and Lazukova, 1995).
Table 3.22. Content of microelements (mg/kg) in the cultural layer, Moscow downtown No. Depth, cm Century Chemical elements Cr N1 Cu Zn As Pb Rb Sr Zr 1 25 beginning of the 20th 98 24 197 1552 74 1321 55 186 220 2 70 18-19 90 29 149 192 36 242 84 289 290 3 100 18 61 24 88 151 16 103 74 222 297 4 115 18 50 12 64 128 13 146 63 188 227 5 145 17-18 92 23 43 107 25 152 69 166 269 6 160 17 92 28 80 256 33 265 74 171 361 7 170 17 83 35 83 134 16 55 78 158 270 8 195 17 91 36 81 104 18 54 73 145 211 22 220 16 81 29 359 398 15 89 78 178 339 Clarke (after Fortescue, 1980) 122 99 30 76 1.8 13 78 384 162 Source: Aleksandrovskaya, 1996. It is also established that both bulk and mobile forms of heavy metals pollute soils (Table 3.23). The share of mobile compounds of heavy metals in their bulk content ranges from 20% for chromium to 80% for manganese. Technogenic anomalies in the content of heavy metals are found in all func¬ tional zones (parks, residential and industrial areas) in the Perovo municipal district. Extremely high contents (index of total accumulation relatively to the background, ITA, is 64 to 80 and more) of heavy metals, primarily of lead, zinc, copper, cadmium, and cesium, are found in soils of the industrial zone. Within the district, high contents of heavy metals (lead, cadmium, and copper with ITA 32 to 48) occur in residential areas, squares, and boulevards. This evidences to strong technogenic deposition of pollutants on soils of the city, since in background soils the fraction of mobile forms is not more than 1 to 5%. The sparse grass cover indicates vegetation decline near roads and industrial enterprises. This promotes formation of dust on the soil sur¬ face, which, in turn, becomes the source of air pollution. On unpolluted refer¬ ence sites, the content of lead in grasses does not exceed 0.5 to 1.0 mg/kg on dry-weight basis, while it is 4 to 12 mg/kg in lawn grasses. The MAC of lead in plants is 10 mg/kg.
The high content of lead in lawn grasses correlates to that content in soil (Table 3.24). Lawn soils contain 2 to 10 times more lead (10 to 15 mg/kg) than the background soddy-podzolic soils of the Moscow region. Table 3.24. Content of lead in lawn grass and soils in Moscow Sampling site Pb content, mg/kg in grass soil Michurinskiy prospect 4.8 54 Leninskiy prospect 5.9 68 Usacheva street (Kauchuk plant) 12.2 83 Komsomolskiy prospect 8.2 65 Leningradskiy prospect 4.2 74 Forest-park in the Vorob'evy Gory 2.5 30 Luzhniki park 7.0 90 Sokol'niky park 5.0 70 Izmailovskiv park 3.0 38 Fili forest-park 2.0 30 Source. Afonina et ai, 1990. Nowadays, significant attention is paid to pollution of soil with deicing salts (primarily with calcium and sodium chlorides) applied on roads and pavements. Generally, according to the geochemical survey (About the Status.... 1993), 22% of Moscow soils is weakly polluted. These are mainly soils in western and northern parts of the city and, more rarely, in its southern part. Nearly 40% of urban soils, mostly located in central and eastern parts of the city, are strongly polluted. The rest 38% of the city area have the average level of pollution (Fig. 3.15). For t! last 15 years, the area of strongly polluted soils in Moscow has increased ai. ost by 150 km2, while the area of slightly polluted soils has de¬ creased by mere than two times. This growth is especially rapid in former clean residential areas on the city periphery. In the center of Moscow, the concentrations of most of the toxic compounds, namely mercury, arsenic, cadmium, and bismuth, exceed their MACs by 30 and more times On the basis of ecological and economic research of the Moscow region, it is pre¬ dicted that within 30 to 40 years, the whole territory of Moscow will be a continuous geochemical anomaly because of strong pollution. The degree of pollution is very variable, though the maximal accumula-
tion is noted for elements of 1st and 2d classes of toxicity. Typically, there are several toxic compounds, whose contents exceed MAC (Pb, Cd, Zn, and Cu). Their synergetic effect deteriorates the situation. Plots with strong pollution occur in industrial zones with metal-consuming production and on city dumps. Fig. 3.15. Scheme of soil pollution with heavy metals. Source: About the Status..., 1993. Conventional symbols: Indexes of Total Accumulation □ <16 CD 16-32 шиш 32-128 The radioactive pollution insignificant in the city. Thus, radiation background in the city, for example, in 1995, was 7 to 20 цг/Ьоиг. Pollution with radionuclides primarily occurs in focuses, which are 3 x 3 m in size and from 0.1 to 0.5-m deep. In Moscow, there are more than 1500 enterprises that use radioactive compounds. Generally, for Moscow, the radioactive conditions (treatments and sources) do not threaten the environment and population of the city. Nevertheless, nuclear reactors, sources of ionizing radiation and radioactive products, and disposal sites located outside the city bear a severe potential and real danger.
Summarizing, we should like to emphasize that the chemical status of urban soils is essentially different from that of soils of rural areas and is char¬ acterized by excessive accumulation of heavy metals, strong shift in pH to¬ wards alkalinity, high base saturation, higher content of nutrients, etc. While being sufficiently provided with major nutrients, urban soils have the follow¬ ing limiting factors for plant development: high pH, strong compaction, and pollution with heavy metals and toxic compounds. Considering this and related changes in pedogenesis, one can confirm the necessity to distinguish industrizems among urbanozems, i.e., strongly polluted and/or chemically changed soils of urban industrial areas, even if the initial profile of native or urban soils is preserved. Presently, special attention is paid to studying the composition and im¬ pact of heavy metals and other toxicants found in urban soils. Our experience of research of urban soil showed that this is just one problem of urban ecol¬ ogy. The composition and content of heavy metals started to affect biological properties of soils and their productivity when their content was by several (more than 5 to 6) times greater than their MACs. In our opinion, not of less importance is the humus content and such water-physical properties of soils as density, permeability, porosity, and texture. Thus, the ecological status of the urban soil cover is of certain theoreti¬ cal and applied interest and its assessment is quite necessary for the im¬ provement of the general ecological situation in urbanized areas. 3.3. Sealed Soils: Their Role in the Urban Ecosystem and Possibilities for Reclamation When studying the ecological situation in cities, one should take into consid¬ eration the extensive sealing of the land surface, which buries soil and induces its degradation. Sealing restricts participation of soil in the nutrient cycling (small biological cycle) and in the great geological cycling of matter and en¬ ergy and makes soil biospherically inactive. Processing of aerial photos revealed that the degree of soil sealing in the center of Moscow reaches 90 to 95%. It is 80% in industrial zones and 60%
in modem residential areas. This is illustrated by Fig 3.16-3.18 developed by us for the Southeastern district of Moscow. The scheme shows the share of open surface (unsealed with asphalt) measured in percents of the total area. This value is the reciprocal of the degree of soil sealing. The surface can be sealed (isolated from the exchange with the atmos¬ phere) by buildings, dense impermeable road coverings (asphalt and cement plates) and permeable coverings (stone, pebble, and wood). Our special at¬ tention was attracted to soils under asphalt concrete, which is a very wide¬ spread road cover in Russia. The Government of Moscow decided to reconstruct and replan some historical sites. For this purpose, we also have investigated the soil cover at the territory of some former cloisters. Under these conditions, the question about the possibility for use of soil cleared from asphalt for the establishment of a vegetation cover becomes very acute. 3.3.1. Structure and Properties of Asphalt Concrete Coverings Since the 1930s asphalt concrete has become the most widespread road covering. It is used for surfacing not only of roads but also of free room between buildings. The word asphalt comes from Greek asphaltos (“mountain tar”). The general meaning of the term includes three constituents: (1) skeleton (60%) consisting of crushed limestone, debris produced during stone crushing, and fine sands; (2) mineral part (10%) consisting of fine-crushed lime, slag and waste products of cement production; (3) binding material (30%) represented by oil and shale bitumen. Despite its impermeable and nonporous appearance, precipitation partly penetrates through the road surface. It is known that the covering can be destroyed in the so-called aggres¬ sive media: acids, alkali, and different organic solvents (Munch, 1992). Bitu¬ men components of road coverings can be dissolved in chloroform, benzene, and petroleum ether. Hence, spilled gasoline can promote destruction of as¬ phalt concrete covering.
Mo4fcv« Rfvar - Residential areas Г1 I I I " Natu«l complex: urban forest, forest-parfc V// A ■ Disposal sites, abandoned lands | 1 Industrial zones: heat and electric power plants industrial enterprises, warehouses, car service I аяг I ' Agricultural areas (1) sealed>75%; (2) sealed by 50-75%; (3) sealed by 25-50%; (4) sealed < 25%. Fig 3.16. Map of share of the sealed suface for the Southeastern district of Moscow.
Industrial areas 26% agricultural areas 8% disposal areas 26% residential areas 40% Fig. 3.17. Distribution of open areas by functional zones in the Southeastern district of Moscow. Share of open soil Fig. 3. IS. Distribution of areas with different share of open areas by functional zones in the Southeastern district of Moscow. R—residential areas; In—industrial zones: heat and electric power plants, industrial enterprises, warehouses, car services; N—natural complex: urban forest, forest-parks; D— disposal sites, unused lands; A—agricultural lands.
3.3.2. The Effect of Land Surface Sealing on the Environment There is almost no input of substances to a sealed soil. Most of the polluted precipitation discharges directly into the river through canalization. There¬ fore, on the one hand, asphalt pavement protects soil, on the other hand, sealed soils do not act as a universal natural filter of the ecosystem against polluted water and dust. Road surfacing changes the boundary structures of the ecosystem. Thus, it indirectly affects unsealed urban soils, which are open for exchange processes. Asphalt concrete covering influences the character of the heat exchange between the soil and the atmosphere. The relationship between the increased temperature and the shrinkage of vegetated area is especially noticeable when the vegetation covers only 20 to 50% of the surface. In city, the temperature regime is favorable for people w'hen the vegetation covers not less than 50 to 60% of the area (Fig. 3.19). This is the reasonable value for urban demands [Formation of Light..., 1975). 50 asphalt cover water 5 grass 0 19 21 23 3 5 9 11 13 15 17 Time, hrs Fig. 3.19. Temperatures at the surface of different substrates in summer (KLaisnit^er, 1987).
A high percentage of sealed areas shifts the preapitation-evaporation bal¬ ance. Already by second to third day after sealing, the moisture content in soil de¬ creases to wilting point moisture (Craul, 1992). Russian geological engineers (Pashkin and Bessonov, 1984) consider that surface paving can result in both groundwater drawdown and rise. Asphalt paving of significant areas near build¬ ings essentially changes the water regime of grounds at their foundations and basements. Basements serve as a one-side water filter, which permits water pene¬ tration to the groundwater table, while prevents its evaporation On the other hand, waterlogging of soils and rocks under asphalt concrete can be so significant that shrubs can grow in cracks between the covering and buildings. 3.3.3. Properties of Sealed Soils under Asphalt We pioneered the research of soils sealed under asphalt concrete on the terri¬ tory of Moscow. We call the sealed soils ekranozems. This term is composed of two Russian words: ekran—screen and zem—soil. Under study were nearly 20 objects in places under reconstruction and archeological excava¬ tions Sealed can be urbanozems, natural soils, urbo-soils, and ur¬ botechnozems (Table 3.25). Table 3.25. Sealed bodies Ekranozems on Sealed grounds natural soils urbo-soils urbanozems (cultural layer, mixed and filled grounds) urbotechnozems ground without pe- dogenic features; human-made ram¬ parts more than 50 cm high The following transformations were recognized in all sealed soils: • compaction (shrinkage—owing to vibration — ranges within 5 to 70 mm/m/year); • changes in the w'ater regime (moisture either cannot penetrate below the covering or once penetrated cannot be easily evaporated); • change in the heat and gaseous regimes (the temperature gradient de¬ creases); • microbiota functioning under anaerobic conditions;
• no input of substances from the outside; • the upper part of the soil profile is destroyed during surfacing. Our observations allow us to consider that at least a part of the precipitation penetrates through the sealing cover. In summer, soil below the cover is wetted to a depth of 10 to 30 cm. Moistening of the lower layers is mainly due to groundwater or water from municipal water pipelines. However, perhaps, atmospheric water may penetrate even deeper in spring and fell. Measurements of the temperature of sealed and typical urbanozems at¬ test that the temperature of soil under asphalt is significantly lower than that of the open surface (Fig. 3.20). 17 June 25 June 15 July 27 July Date 25 17 June 25 June 15 July 27 July Date Цunder asphalt (0-5 cm) Bunder asphalt (15-20 cm) □ open soil surface Qopen soil (15—20 cm) Fig 3.20. Moisture and temperature dynamics in urbanozem (1992).
This difference is not so significant at the depth of 15 to 20 cm, while the temperature is stable in both variants. We monitored the moisture dy¬ namics in a sealed loamy sandy urbanozem on the territory of the Rozhdest- venskiy Convent (pit 6). According to its data and morphological descriptions of other pits, one can conclude that soil moisture content directly under road covering exceeds that in the surface layer outside the road covering (by 15%). Iron microconcretions accumulated at the depth of 5 to 10 cm under the road covering attest to the presence of alternating reduction and oxidation condi¬ tions. T\picallv, wetness was almost the same at the depth of 15 to 20 cm for sealed and unsealed soils. Despite their diversity, soils under surface covering have some common properties described below. This allows us to recognize a special subtype of urban soils provisionally called ekranozem. Profiles shown on Fig 3.21 illustrate the diversity of different urban soils sealed with asphalt concrete. Fig. 3.21. Types of soil profiles of ekranozems. Profile 1. Ekranozem on shallow replantozem. Profile 2. Unsealed replantozem. — ?• .** A e. « ** - ' f r v 46 OO о J о 0 a & о -Ц- (0 t - J ' 1 1 j 10C 1 2* qfilifwSi Bpyjg 100 120 »«• 1 о <to IM о UO 1(0 ?m| Profile 3. Ekranozem on shallow' urbanozem. Profile 4. Ekranozem on shallow urbanozem. Profile 5. Deep unsealed urbanozem.
The asphalt covering is very rarely placed directly on the soil. To make the road resilient, the covering should be in a close contact with underlying layers and is placed on a leveled surface. Usually, road paving is performed by either raising several ground layers for leveling the surface, or, vice versa, by the removal of the upper soil layer. The leveled surface is very often forti¬ fied with concrete that tightly binds asphalt layers to the underlying surface. The humus content in different horizons of the studied ekranozems ranged from 0.5 to 6.0%. Earlier studies of Moscow soils (Agarkova et al., 1991; Strogonova et al, 1993) revealed that, on an average, different layers of ekranozems contained less humus than the topsoil of unsealed urbanozems. All city soils are characterized by rather high carbonate content and the pH ranging within 7.5 to 9.0. Additional carbonates can accumulate in ekranozems due to cover destruction. They concentrate in upper layers of the sealed soil. The other reason of their appearance is a specific water regime. Water rarely penetrates below' the cover. Nevertheless, once got there, it evaporates very slowly. As re¬ vealed by chemical and micromorphological analyses, carbonates begin to accu¬ mulate at the depth of 10 to 15 cm. Their content is higher than 2%. According to micromorphological data, ekranozems are characterized by a greater amount of carbonate neoformations compared to unsealed soils. Carbonates occur as sparitic nodules and calcitic coatings along with micritic bridges between grains of the sandy skeleton. Accumulation of carbonates is traced in thin sections obtained from deep layers of all horizons of ekra¬ nozems. The content of heavy metals in sealed soils in the center of Moscow' exceeds their background content. Protective properties of the covering also should be mentioned. In sealed bodies, there is no accumulation of Co, Cd, and Ni, while they accumulate in unsealed urban soils. In addition, soils and grounds of new' residential areas sealed about 20 to 30 years ago are poor in almost all heavy metals (Table 3 .26). As for major nutrients (N, P. and K), their content in sealed soils is similar to that in urbanozems. All sealed soils are featured by the increased content of available P (50 to 600 mg/kg of P2O5). At the same time, the con¬ tent of К is high (40 to 200 mg/kg of K20), while that of N (traces to 10 mg/kg) sufficiently depends on the organic matter content in soil (Table 3 .27). Ekranozems are unable to perform many biocenological functions. Nonetheless, there is a weak gas exchange with the atmosphere and microor¬ ganisms. Plant roots can penetrate through the asphalt, while grasses and tree seedlings may grow in cracks of old coverings. Earthworms can stmcturize
the soils even below the cover. The covering creates new microbiological conditions under which an¬ aerobic microoiganisms develop. They live due to fermentation and reduction of nitrates and sulfates. Sometimes their index of abundance increases. Lower and more stable temperatures below the asphalt covering favor development of specific psychrotrophic microoiganisms. The basic microbial community that decomposes plant and other organic debris are the spore-producing bac¬ teria. In soils beneath the asphalt, their development is essentially oppressed. Table 3.26. Content of heavy metals in ekranozems and unsealed soils (extraction with IN HN03, mg/kg) Soil Depth, Heavy metals cm Pb Cu Zn Cd Co Ni Replantozem. 0-10 45.5 33.4 60.5 0.19 1.87 5.05 Profile 2 10-20 104.0 18.0 31.1 0.03 1.15 2.64 (control) 20-30 6.0 12.3 15.1 0.10 1.51 1.90 Ekrcmozem 8-14 12.3 11.9 22.7 0.05 1.44 2.68 on 14-19 8.51 10.3 13.8 0.07 1.10 1.72 replantozem. 19-29 3.75 7.2 9.0 0.00 0.65 2.76 Profile 1 29-40 2.79 8.4 8.7 0.00 0.54 1.32 Deep unsealed 0-10 185 63.4 151 0.71 2.17 6.20 urbanozem. 10-30 186 71.1 130 0.58 2.28 5.31 Profile 5 30-50 245 55.1 76.5 0.30 2.17 4.06 (control) 70-90 140 69.9 49.7 0.32 1.70 3.25 90-110 131 77.4 41.0 0.23 1.81 3.27 110-130 227 296.9 72.0 0.59 1.94 4.47 Ebnnozem 0-8 37.5 20.0 45.0 0.00 on shallow 8-25 60.0 26.0 55.0 0!20 n/d n/d urbanozem. 25—49 25.0 14.0 27.5 0.00 Profile 3 49-108 25.0 17.0 26.0 0.00 Ekranozem 0-5 1.93 4.32 5.28 0.00 7.15 1.15 on the deep 5-10 14.7 6.70 8.62 0.01 1.25 2.61 urbanozem. 10-25 38.1 39.14 23.2 0.03 1.11 2.19 Profile 4 90-150 187.7 49.67 119 0.12 9.98 3.18 150-170 4.95 16.84 10.5 0.12 1.41 2.03 Shallow 0-10 234 69.7 239 0.53 1.34 5.55 Urbanozem. 10-70 373 57.3 285 0.66 1.98 4.98 bricks Profile 6.a 85-110 108 22.1 68.8 0.20 . 1.45 3.57 (control) 110-120 32.7 13.8 28.3 0.09 1.33 3.01 Ekranozem 0-5 275 60.0 160 0.80 on urbanozem. 5-10 250 63.0 150 0.60 n/d n/d 10-20 225 75.0 130 0.60 Profile 6 20-60 250 59.0 110 0.60 Note: is not determined.
Table 3.27. Chemical properties of urban soils and their sealed analogues Soil DepUl, cm рНш CaCOj, % Humus, % PiO*. mg/kg K20, mg/kg NH* mg/kg Replantozem. (MO 8.1 1.18 1.37 158.0 76.0 2.37 Profile 2 10-20 7.9 1.34 0.61 15.0 96.0 1.94 (control) 20-30 7.9 0.00 0.60 97.0 44.0 1.29 Ekranozem 8-14 7.9 0.17 1.37 82.0 60.0 0.86 on replantozem. 14-19 6.8 0.00 0.61 71.8 55.6 1.08 19-29 7.3 0.00 0.60 102.0 44.0 0.43 Profile 1 29-40 7.1 0.00 n/d 93.0 38.0 n/d Deep unsealed 0-10 8.0 2.83 3.38 13.5 104 7.99 urbanozem. 10-30 8.5 3.71 1.86 12.2 118 1.94 Profile 5 30-50 8.5 4.62 1.62 46.6 14.8 1.93 (control) 50-70 8.3 3.68 1.69 n/d n/d n/d 70-90 84 4.83 2.00 n/d n/d n/d 90-110 8.3 3.05 n/d n/d n/d n/d 110-130 8.3 5.25 2.14 n/d n/d n/d 130-155 8.3 8.3 n/d n/d n/d n/d Ekranozem 0-8 8.4 0.76 3.22 180.0 96.8 2.5 on the shallow 8-25 8.6 1.66 1.33 236.0 141 2.0 urbanozem. 25-49 8.5 0.00 0.36 127.0 62.8 2.2 Profile 3 49-108 8.5 0.27 0.26 96.8 69.6 2.2 Ekranozem 0-5 7.1 2.11 1.03 n/d n/d n'd on the deep 5-10 7.8 0.40 0.84 9.61 83.2 6.0 urbanozem. 10-25 8.3 2.85 1.37 2.39 178 3.4 Profile 4 25-45 9.3 3.76 n/d n/d n/d n'd 45-67 9.2 1.28 3.05 n/d n'd n'd 67-90 8.9 2.13 5.90 n/d n/d n/d 90-150 7.8 1.42 5.80 n/d n'd 13 150-170 7.7 0.00 1.46 n/d n/d 7.3 Shallow 0-10 7.9 4.72 2.78 43.7 106 4.79 urbanozem. 10-30 7.5 3.78 2.16 47.4 142 4.75 Profile 6a 30-70 bricks 8.0 3.57 2.43 n/d n/d 11.4 (control) 85-110 8.2 2.73 1.93 n/d n'd n/d 110-120 7.9 2.10 1.55 n/d n/d n/d Ekranozem 0-5 7.7 3.80 3.76 275 179 4.0 on urbanozem. 5-10 8.0 3.46 2.95 312 251 5.0 10-20 8.1 3.73 3.59 339 233 3.6 Profile 6 20-60 8.1 3.80 3.31 335 203 3.2 Ekranozem on 0-5 9.3 3.74 0.61 15.5 40.8 2.5 urbo-soddy-podzolic 5-10 9.3 0.30 0.38 24.7 43.2 3.4 soil. 10-20 9.1 1.33 1.05 54.1 158 6.4 20-40 8.7 0.76 1.49 90.0 124 n/d Profile 7 40-80 8.1 0.37 n/d 33.7 154 0.6 Note: n/d is not determined.
Less aeration of the sealed substratum is attested by a low content of aerobic nitrifier—Azotobacter. As noted, its content decreases by 1.5 to 2.0 times compared to that in unsealed soils (Skvortsova et al., 1997). The question is if it is possible to consider the substrate sealed by the asphalt concrete cover as soils is still a matter of discussion. However, this body has morphological characteristics of soil and performs some its func¬ tions. Methods used in soil science can be applied to investigate these soils. 3.3.4. Ways for Remediation of Sealed Soils The described properties of sealed soils and the perception of the urban cul¬ tural layer as a system of buried soils enable us to give some advises to city managers how to adjust ecological conditions in the city for human life. In our opinion, we should regulate to some extent the sealing of the soil surface and use porous and ecologically safe materials for road surfacing. In this respect, one can remember that once streets of Moscow had been paved with blocks placed on a 20-cm layer of sand. Now blocks are paved on the layer of the same thickness but made of concrete. Such a cover is as imper¬ meable as several layers of asphalt concrete. At the German-French conference “Development of Road Construction in Some European Countries'’ (1992), special attention w'as paid to the im¬ plementation of draining asphalt for road covering during construction and reconstruction. Because of better evaporation through such an asphalt, the threat of waterlogging of foundations and basements of buildings with groundwater is partially eliminated. In addition, it improves the water regime of urban soils and conditions for plant growth. The asphalt concrete cover exerts both direct and indirect effect on components of the urban ecosystem. In this respect, on one hand, it is neces¬ sary to improve the technology of cover production. The cover should be more permeable for water and air than it is allowed by present technologies. On the other hand, we should restrict sealing of the land surface. This is be¬ cause at the modem technological level it is not enough to replace the type of cover to improve significantly soil functioning and plant growth. When compared to soils of unsealed areas, ekranozems are less subject to the effect of the environment. They preserve information about the history of the urban landscape and can serve as a planting reserve.
In conclusion, we hope that this knowledge will be useful for controlling the ecological situation in cities, efficient nature protection, and improvement of the living conditions for people. 3.4. Soil Cover of Moscow Urbanization and economical activities are significantly responsible for het¬ erogeneity of the soil cover in the city. Dissected topography also contributes to that as it determines drainage conditions and water regime. The complexity of the soil cover is also due to differences in the age of the area.Thus, the soil cover changes from the downtown with its thick cul¬ tural layer to newly developed areas where soils develop on recently tipped or mixed grounds. The degree of contrast and the heterogeneity of the soil cover is also a result of the complicated history of the city and of the mixing of cultural layers with buried soils. It is very difficult to map urban soils, especially urbanozems, because their properties are very variable. Common methods for mapping of natural soils cannot be merely applied. The mapping of urban soils is also compli¬ cated by the absence of a classification system suitable for urban soils. We compiled a medium-scale schematic soil map of Moscow (Fig. 3.22, Table 3.28). The schematic map is based on original and literature data and maps published in the state report About the Status of the Natural Environ¬ ment in Moscow in 1992 at a scale of 1:200,000: (1) geomorphological map; (2) map of reconstructed landscapes; (3) map of functional organization of the territory; (4) map of soil pollution; (5) map of waterlogging of the territory with groundwater; (6) maps of landslide, karst, and subsidence phenomena; (7) map of vegetation damage, and other maps, and color aerial photos at a scale of 1:25,000 per¬ formed by Aerogeologiya. We presumed the following approaches to be important: A. lithological and geomorphological division of the territory: (1) gently rolling interfluves with till and mantle loams; (2) flat glaciofluvial plain sandy and loamy sandy deposits;
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Conventional signes: -I -II -III -IV - arable improved soils - nonuscd soils, disposable sites, quarries cemeteries - cemeteries Fig. 3.22. Schematic soil map of Moscow Roman numerals (I -IV) are landscape types in table 3.28
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(3) terrace deposits composed of alternating sands and loams; (4) the flood plain of the Moskva River and its tributaries. B. The age of the area (downtown, developing areas, etc.). C. Functional zones of the city: (1) residential area; (2) industrial zone, thermal power stations, industrial enterprises, ware¬ houses, and car services; (3) Natural complex: city forests, forest-parks, etc. On the map, areas of agricultural lands, unused lands, dumps, and quar¬ ries are shown by conventional symbols because of their small size. The schematic map records differences in pedogenesis on various parent rocks, both semi-natural and artificial. The schematic soil map of Moscow is the first Russian map of the ur¬ ban territory. It presents the city soil resources, spatial and functional depend¬ encies between soils and soil cover and the environment. The map used the classification of urban soils developed by the authors and the new national classification of natural soils. When compiling the map, we accounted for the Soil Map of Western Berlin (Bodengesellschaften, 1984, author R. Grenzus, editor H.-P. Blume, 1:75,000). The presented schematic soil map of Moscow can become a basis for a series of applied maps, including soil-ecological map, map of chemical and microbiological pollution, map of erosion of urban lands, etc. One reason for the irregular distribution of soils is the land-use pattern in cities. In cities, the proportion of open, unsealed, plots with normal soil cover ranges from 3 to 5% in the center and 70 to 80% in the suburbs. I. The soil cover of hilly to broadly undulating interfluves. Soils devel¬ oped on till and mantle loams partially overlaid by a sandy cultural layer oc¬ cupy nearly 20% of the city area. This type of soil cover occurs in southern, southwestern, and partially in the northern parts of the city. In residential ar¬ eas, which occupy 12% of the city area, slightly to medium thick urbanozems with low' to medium humus content are fpund (Fig. 3.22, 1). In the central part of the city, urbanozems occur on the cultural layer. Large areas are oc¬ cupied by sealed soils — ekranozems. In the industrial zone (3%), soils are represented by industrizems on filled grounds and partly by urbanozems. Disturbed bog soils occupy depressions. Small spots of intruzems occur near some gasoline filling stations, while replantozems are frequent in recently de¬
veloped areas (Fig. 3.22, 2). Soils of urban forests and forest-parks (4%) are least disturbed. There soddy-podzolic and soddy-urbo-podzolic soils on till and mantle loams dominate the upper parts of catenas, while peat bog and soddy-podzolic gleyed and gley soils are identified in depressions and foot¬ hills (Fig. 3.22, 3). II. The soil cover of the flat glaciofluvial plain has sandy, loamy sandy, and sandy loamy deposits as parent material. It occupies nearly 18% of the city area. Small fragments of this type of the soil cover are dispersed both in northern and southern parts of the city. In residential areas (10%), ur¬ banozems are formed on glaciofluvial sands and loamy sands as well as on tipped, moved, and mixed grounds. Their humus layer is medium to very thick with low to medium humus content. In the city center, ekranozems are widespread, while urbanozemv are confined to the sandy cultural layer. Intru- zems occur near some gasoline filling stations. Replantozems are found in re- cently developed areas (Fig. 3.22, 4). In the industrial zone (3%), the occur¬ rence of complexes of industrizems and urbanozems depends on the degree of chemical pollution of soils. As natural drainage becomes worse, semihydro- morphic soils (gleyed urbanozems and peaty soils) appear in small flat closed depressions and flat, leveled plots characterized by waterlogging and groundwater raise (Fig. 3.22, 5). Natural soddy-podzolic and soddy-urbo- podzolic soils (4%) occur in city forests (e.g., Losiny Ostrov) and forest- parks (Fig. 3.22, 6). III. The soils on the terraces of the Moskva River are formed от sandy and loamy sandy deposits, somewhere overlaid by mantle loams. This type of the soil cover makes up the significant part of the city (35%). Topography and, hence, the soil pattern of terraces were strongly changed. The territory' was mostly leveled with the majority of gullies filled. The soils now develop on technogenic layers of 1- to 20-m depth. In parts of the city where topography remained dissected by gullies, soil erosion is com¬ mon. In the last decades, cutting up and filling of slopes and uncontrolled rain and meltwater runoff have significantly promoted soil erosion. In the residential area (21% of the area of these landforms), slightly to medium thick urbanozems with low to medium humus-enriched topsoil layer occur. Recently developed areas are typified by replantozems and shallow urbanozems. Ekranozems on the cultural layer are widely found in the city center (Fig. 3.22, 7). In the industrial zone (7%), strongly polluted soils are
represented by industrizems and intruzems in association with urbanozems. Sealing of the soil surface is also quite common (Fig. 3.22). In this part of the city, areas with natural soils were preserved (6%) in for- est-parks (Vbrob'evy Gory, Neskuchny Garden, Fili park, etc.). Natural soils are represented by soddy-podzolic and soddy-urbo-podzolic soils, which are differ¬ ently disturbed and partly eroded. Natural soil associations are well drained soddy-podzolic soils cm watersheds, semihydromorphic soddy-podzolic gleyed soils on gentle slopes, and bog soils in depressions (Fig. 3.22,9). IV. The soil cover of the flood plain of the Moskva River and its tributaries (15% of the total area) was drastically changed because of strong alteratoin of the topography. Here, gullies and washouts earlier opened to the valley of the river and its tributaries were filled. The flood plain was either partly flooded with water from reservoirs situated upstream, or it was risen by three to four meters by filling. Vast areas are under damps, abandoned lands, and filtration fields. Although very specific, the soil cover is very poorly studied. Nonetheless, the flood plain (nearly 10% of the area) is mostly built up, so urbanozems and replantozems are formed on filled and moved grounds (Fig. 3.22, 10). Arable soils are found on slopes and in bottoms of small tributaries of the Moskva and Yauza rivers. Overall, throughout Moscow, poorly and well-improved arable soils, in¬ cluding agrourbanozems {culturozems), occur on 5% of the city area on various topographic elements. 3.5. Assessment of the Ecological Status of Typical Landscapes 3.5.1. Memorial Territories in the Moscow Downtown The ecological status of areas around historical complexes and ensembles in the center of Moscow was examined during 1991 and 1992 in the Rozhdest- venskiy and Zachat'evskiy convents, and in a park around the Yusupovskiy Palace. Tree and grass layers were valued by the following criteria: vitality (satisfactory, unsatisfactory, damaged plants, and declining plants), leaf abundance and damage of crown and leaves. Each stand was assigned with a quality class. Thus, the general estimation of the state of tree stands in this
area was obtained. The grass cover was estimated through species diversity and coverage. Physical and chemical properties of soils were analyzed. On the basis of the obtained results, maps of the ecological status of three key sites were compiled. 3.5.1.1. Rozhdestvenskiy Convent The Rozhdestvenskiy (Nativity) Convent is situated on the high bank of the Neglinka River, l .3 km to the north of the Kremlin. Absolute elevation is 153 to 156 m above the sea level. Among the oldest buildings are the Cathedral of St. John the Zlatoust (Gold-lipped), burial building, and canteen constructed in 1676. Buildings of the convent were periodically reconstructed, and its ter¬ ritory was rearranged. Because of these activities, the cultural layer grew thicker. Before 1921, it was stricdy prohibited to walk over or to perform any works at some places (“unpassable sites”). Also, the convent had an orchard with improved fertile soils. The convent established in 1386 was closed from 1921 to 1992, and its territory was replanned. In the 1930s, a school has been built on the site of the cemetery and orchard. Simultaneously, communica¬ tions were installed and large areas were paved. In 1991, the church has got back the building of the cathedral. Later, the convent was re-established and it started to gradually return the other buildings. The present-day territory of the convent is very irregularly disturbed and built-up. The open surface is 13% from the total area. The peripheral, open part of the area is strongly dumped (by 25 to 75%) with household and con¬ struction wastes (Fig. 3.23). Trees within the area of the convent (linden, ash, poplar, and birch) are up to 100 years old. Trees and shrubs (hawthorn, lilac) are damaged and are characterized by poor growth and development. Their vitality is low as evi¬ denced by dry branches and few leaves (less than 50%). Up to 40% leaves have necrosis and other damages; 10 to 50% of the leaf surface is strongly damaged by chlorosis and insects; tree boles are also damaged (hollows, rots, and fungi) As a result, trees and shrubs lost their aesthetic value and resil¬ ience to environmental effects. The grass cover is dominated by low-productive ruderal species. Pene¬ tration of sucking roots of trees to the soil is restricted by layers with abundant solid inclusions and plates, typically occurring at the 1-m depth. Roots, which
Depth of high-humus layer, cm ШЛ 25 '50 50-75 Abundance of brick fragments. % L1 few LZ <25 L3 -25—50 L4 50-75 □ sealed surface buildings • absolute elevation Fig. 3.23. Rozhdestvensky Convent: Depth of the high-humus layer and abun¬ dance of brick fragments. strongly branch above these layers, almost do not penetrate deeper. Branching of grass roots usually starts from the depth of 10 to 15 cm, so escaping the most polluted upper soil layer. These peculiarities of the rooting system are reflected in the quality of tree stand and grass cover. The soil cover is unevenly disturbed within the convent and fragments of brickwork were found at the depth of 70 to 80 cm near the stump of a 200-year-old oak tree. The soils on the cultural layer with varying thickness are presented by loamy sandy and sandy loamy urbanozems. They contain abundant construc¬ tion waste: fragments of bricks, limestone, and stones (Fig. 3.23). Soil pro¬ files are weakly differentiated and comprise tipped layers. The top humus- enriched dark gray or brownish gray layer is 35- to 70-cm thick. At the depth of 30 to 100 cm. some layers contain abundant construction waste, which comprises up to 50 to 75% and more of the soil volume (profiles 1-91, 3-91). The high topographic position of the convent, good drainage, and the sandy texture of the soil do not favor gley development. Nonetheless, atmospheric water can stagnate above the human-made compacted layer. Because of anaerobic conditions, gray-blue mottles or con¬ tinuous gley horizons develop (pit 3-91). The sandy texture of all soils in the Rozhdestvenskiy Convent predetermines their high permeability (Table 3.29). *149д Rogdestvenka street
The spatial heterogeneity of the soil-forming layer results in both water stag¬ nation and downfall percolation of water. So, the rate of infiltration changes from 1.8 to 7.3 mm/min. The best permeability is noted in rarely visited places (profile 3-91). Table 3.29. Water-physical properties of urbanozems Pit no. Depth, cm Density of fine earth, K/cm3 Rate of infiltration, mm/min Rozhdestvenskiy Convent 1-91 0-10 1.3 1.8 35-45 1.2 n/d 75-85 1.0 n/d 3-91 0-10 1.1 7.3 40-50 1.2 n/d 80-90 1.0 7.1 5-91 0-10 n/d 2.6 Yusupovskiy park 18-91 0-10 n/d 9.7 19-91 0-10 1.15 3.9 24-91 0-10 n/d 9.9 25-91 0-10 1.20 n/d 30-40 1.40 n/d Soddy-podzolic 0-20 1.20 1.6 loamy soil 20-40 1.40 n/d Note: n/d is not determined. All soils of the area are calcareous. The content of CaC03 changes from 2 to 14.5% along the whole profile. Soils have slighdy alkaline to alkaline re¬ action (pHwaer from 7.1 to 8.6). Their high content of humus (up 6%) and nutrients is typical for urbanozems (Table 3.30). Most of the soils of the open areas in the Rozhdestvenskiy Convent are polluted with heavy metals (Table 3.31). The content of all determined ele¬ ments exceeded the background ones by several times. Thus, the concentra¬ tion of acid-soluble forms of lead, zinc, and copper was by 10-20, 10, and 5- 7 times liigher, respectively. To reconstruct the historical landscape of the Rozhdestvenskiy Convent and to restore its soil and vegetation cover, it is necessary to reclaim the pol¬ luted surface layer of 30-cm depth .
Table 3.30. Chemical and phisical of urbanozems Pit no Horizon Depth, cm Н|мшв,% ptUr CaCOj,% PjOs KzO Partkfe-dze dbbribiriion pfealavtdable mg/lOOgofsoi <0.005 <0.01 teituraldass Roihdestvenskiy Convent 1-91 Ulh 0-10 2.86 7.70 5.46 46.6 21 7 16 loamy sand 10-20 6.75 750 5.14 48.2 11 n/d n/d U2 20-30 3.89 7.80 10.9 45.0 13 10 18 loamy sand U3 30-50 2.44 8.30 14.50 38.6 10 11 18 loamy sand 50-70 2.59 8.10 4.20 n/d n/d n/d /d U4 90-105 3.86 7.10 5.56 n/d n/d n/d n/d 105-130 1.86 8.60 9.50 n/d n/d n/d n/d 3-91 Ulh 0-10 2.78 19 4.72 43.7 11 10 15 loamy sand 10-30 2.16 7.5 3.78 47.4 14 n/d n/d 30-50 3.75 8.0 3.78 n/d n/d 10 15 loamysand 50-70 2.43 8.0 3.57 n/d n/d n/d n/d U2 75-85 1.93 7.7 2.73 n/d n/d 11 13 loamy sand U3 85-110 1.55 8.2 2.10 n/d n/d 10 15 loamy sand U4 110-120 n/d 7.9 2.20 n/d n/d 8 10 loamy sand 5-91 Ulh 0-10 4.03 83 3.82 36.3 27 n/d n/d 10-20 4.59 ru'd n/d n/d n/d n/d n/d 20-40 3.00 8.0 5.46 32.0 41 n/d n/d U2h 35-60 4.00 7.9 7.14 n/d n/d n/d n/d 60-85 5.19 8.0 5.88 n/d n/d n/d n/d U3h 85-112 5.38 7.7 6.82 n/d n/d n/d n/d Zachat'evskiy Convent 32-91 Ulh 0-10 1.83 7.5 10.8 10.5 11 9 14 loamy sand U2h 30-50 2.90 7.8 11.8 n/d n/d 8 13 loamy sand U4 50-85 5.03 7.5 4.52 n/d n/d 9 16 loamy sand U5 85-100 1.24 8.0 1.55 n/d n/d 18 23 sandy loam 35-91 Ulh 0-10 3.76 73 3.57 20.0 10 n/d n/d U2I 10-30 n/d 7.0 4.62 n/d n/d n/d n/d 30-50 2.24 7.5 6.08 153 11 n/d n/d 50-75 3.52 8.3 7.76 n/d n/d n/d n/d 36-91 Uld 0-10 4.31 83 5.35 16.2 12 n/d n/d U2h 10-20 2.06 8.3 7.34 10.3 10 n/d n/d 50-85 n/d 83 n/d n/d n/d n/d n/d 38-91, Uld 0-10 1.69 8.9 8.18 12.2 12 n/d n/d U2 10-30 2.09 8.2 6.08 13.2 11 n/d n/d 30-50 1.62 8.3 3.84 n/d n/d n/d n/d Yusupovskiy park 25-91 Ulh 0-10 3.38 8.0 2.83 13.5 14 6 9 sand U2h 10-30 1.86 8.5 3.71 12.2 12 7 11 kxtmysand из 30-50 1.62 8.5 4.62 46.6 15 6 10 sand 50-70 1.69 83 3.68 n/d n/d n/d n/d U4 70-90 2.00 8.4 4.83 n/d n/d 7 8 sand U5 90-100 n/d 83 3.05 n/d n/d n/d 11 loamy sand 110-130 214 83 5.25 n/d n/d n/d n/d 130-155 n'd 83 n/d n/d n/d 8 12 loamy sand Note: n/d is nol determined.
Table 3.31. Content of heavy metals in urbanozems (extraction with IN HN03, mg/kg) Pit nos. Type of land use Horizon Depth, cm Elements Pb Cu Co V Cd Zn Ni Rozhdestvenskiy Convent l—91. Ulh 0-10 111 56 1.3 8.7 0.9 460 7.1 Square near 20-30 140 57 2.7 9.1 1.3 493 6.1 school U2 35-50 215 70 2.5 5.4 0.3 183 4.1 U3 50-70 107 38 1.7 5.6 0.2 77 5.2 U4I 105-130 151 67 2.2 9.2 0.3 124 4.3 3-91. Ulh 0-10 234 70 1.3 6.4 0.5 239 5.6 Flowerbed 30-50 373 57 2.0 6.2 0.7 285 5.0 U2 75-85 114 31 2.5 4.1 0.2 60 2.2 из 85-110 108 22 1.4 4.6 0.2 69 3.6 U4 110-120 33 14 1.3 3.9 0.1 28 3.0 5-91. Ulh 0-10 211 93 1.4 7.4 0.4 160 7.2 Flowerbed 10-20 136 69 2.0 10.2 0.4 117 6.6 U4 112-122 137 50 2.4 2.7 0.6 55 0.7 Zachat'evskiy Convent 32-91. Ulh 0-10 40 39 2.2 5.8 1.7 115 9.7 Lawn U2h 30-50 873 114 2.8 7.5 0.5 197 4.7 U4 50-85 473 75 1.7 6.0 0.5 114 4.3 U5 85-100 93 15 2.0 6.0 0.4 36 3.5 35-9. Ulh 0-10 267 80 0.3 n/d 1.0 292 9.3 Flowerbed U21 10-30 267 70 3.1 n/d 0.7 265 7.3 30-50 307 57 2.4 n/d 0.6 345 4.0 50-75 437 79 1.9 n/d 0.6 126 5.4 36-91. Uld 0-10 345 93 2.2 n/d 1.1 484 7.3 Square U2h 10-20 318 93 2.5 n/d 1.0 597 7.3 38-91. Uld 0-10 165 66 2.8 n/d 0.7 624 5.7 Square U2 10-30 229 46 2.3 n/d 0.3 67 3.4 30-50 144 34 1.7 n/d 0.3 85 3.4 Yusupovskiy park 25-91. Ulh 0-10 185 63 2.2 9.8 0.7 151 6.2 Park U2h 10-30 186 71 2.3 5.8 0.6 130 5.3 U3 30-50 245 55 2.2 5.7 0.3 77 4.0 U4 70-90 140 70 1.7 2.2 0.3 50 3.2 U5 90-110 131 77 1.8 3.5 0.2 41 3.3 110-130 227 297 1.9 5.8 0.6 72 4.5 Note: n/d is not determined. 3.5.1.2. Zachat’evskiy Convent The Zachat'evskiy (Conception) Convent was established in 1623 by the grandfather of Peter the Great. It is situated in Zemlyanoi Gorod on the 2nd terrace of the right bank of the Moskva River at a distance of 1.3 km south¬ west of the Kremlin. It was built on the site of the earlier destroyed cloister.
Hence, this area has being used by monks for more than 600 years. The Zachat'evskiy Convent was closed after the October Revolution in 1917. In the 1930s, the area of the convent was reconstructed, and buildings were partly dismantled. Thus, only the gateway church of the Savior and fragments of the walls have been preserved. A school was built on the site of the cemetery; and an orchard was established nearby. Most of the territory (65%) was paved. Presently, convent buildings are under intensive restora¬ tion. The surface of the open area is especially dumped on the periphery of the convent (25 to 75%), while its central part is better managed. Elm, maple, poplar, linden, mountain ash, and apple trees under 80 years old grow along the preserved monastery walls. Their state is satisfac¬ tory'. The central part of the area is occupied by dying trees; leaf density on crowns is 50 to 80%, while damage of crown and leaf surface is 20-40 and 90%, respectively. Leaves have necrotic signs. The soil cover of the area of the Zachat'evskiy Convent is composed of loamy sandy and sandy loamy urbanozems with, high content of construction and household waste, formed on the cultural layer. The profile differentiation Depth of the high-humus layer, cm <25 25-50 50-75 A 128.3 2d Zachat'evslcy lane 75-100 Abundance of brick fragments, % L1 few L2 <25 L3 25-50 L4 50-75 ■ building sealed □ surface a absolute elevation Fig. 3.24. Zachat'evskiy Convent: Depth of high-humus layer and abundance of brick fragments.
of the urbanozems vary from weak to strong. Typically, the upper 20-30-cm thick horizon of the urbanozems is dark grey, loose, and rich in humus. It is underlaid by more compact mixed layers, which contain 25-50% and more waste. The high waste content is a typical feature of all soils at the territory of the convent when compared to other investigated objects (Fig. 3.24). The soils contain carbonates throughout the profile. Their pH (7.2 to 8.9) is alka¬ line (Table 3.30). In addition, they are strongly polluted with heavy metals, especially with lead (by up to 60 times stronger than the background values) and zinc (by 10 times) (Table 3.31). Despite strong stoniness of the soil profile, the upper soil layer is fertile and is constantly improved by application of fertile mixtures and consequent loosening. Urbanozems that occur in the central part of the area are highly fertile. Therefore, during reconstruction of the area, the surface soil layer should be completely substituted, while revegetation should be made in ac¬ cordance with the historical landscape. 3.5.1.3. Yusupovskiy Park A park of 0.6 ha has been established in the 17th century around the palace of prince Yusupov. It is situated on a watershed plain at a distance of 2 km northeast of the Kremlin. In the end of the 1940s, the subway has been con¬ structed in the neighborhood of the park. Excavated ground and construction wastes were spread throughout the neighboring territory, including the park. In 1951, the park has been re-established and arranged, and some new trees have been planted. The tree community of the park (linden, birch, and ash trees) is similar by its structure to the natural forest and is in a satisfactory state: it has a well- developed undergrowth and forest and meadow herbs in the lower canopy. The leaf abundance is 30 to 70%. Crowns are damaged by up to the degree of 50% (30%) on the average). Leaf damage is 5 to 20% (5 to 10% for birch). The projection of leaves is 5 to 40%. Tree roots are found along the whole studied depth down to 150 cm. Grass roots are distributed within the layer of up 0 to 30 cm. The soil cover of the park is homogenous and represented by thick un¬ derlaid by loamy sandy and sandy loamy urbanozems developed on filled-up
sites. They have a low content of construction waste in the 0 to 50-cm layers and its medium content in the 50 to 100-cm layer. The soil profile has a loose well-structured, dark gray humus horizon up to 30-cm thick strongly compacted filled layers with irregular bedding. They may contain up to 2.14% humus at the depth of 110 to 130 cm. These soils display good structure despite their sandy texture. They are weakly compacted at the surface and at the depth of 30 to 40 cm (Table 3.29). This favors vegetation development. The rate of infiltration is high: 3.2 to 50.0 mm/min. The soil contains carbonates throughout the profile with a maximum in lower horizons (5.25% CaC03 at the depth of 110 to 130 cm). The surface horizon is the most leached (Table 3.30). Such a distribution of carbonates is explained by the high amount of construction waste in the subsoil. The soils have the alkaline reaction (pH >8.0) along the whole profile. The soils of the park accumulate heavy metals. The content of lead and zinc is by 15 and 3-4 times higher than their background values, respectively. The accumulation of other minor toxic elements is insignificant (Table 3 .31). Thus, the status of the soil cover and vegetation in the Yusupovskiy Park is much better compared to other historical monuments under study. Nonetheless, the soils of the park are also strongly polluted with many chemi¬ cal elements. 3.5.2. The Lyublino-Pererva Industrial Zone Presently, 68 industrial zones are recognized within the limits of Moscow Ring Road. They occupy 14,380 ha, or 16.8% of the city area. Industrial zones concentrate nearly 50% of production and 20% of research institutes of the city (Fig. 3.13). The Lyublino-Pererva industrial zone is situated in the Southeastern Ad¬ ministrative Region of Moscow—the main source of air pollution in the city (26.8% in 1995). It was chosen for a case study to exemplify the ecological status of in¬ dustrial zones. This is one of the biggest and most polluted (according to the complex estimate) zones in the city. Materials of Research and Production In¬ stitute of the General Plan of Moscow, of the Institute of City Ecology, and of
our original surveys of the territory were used to describe the components of the environment. The Southeastern Administrative Region is one of the biggest in the city. Industrial objects presorted by nearly 11,000 enterprises and organizations, in¬ cluding 800 industrial and 230 transport enterprises, occupy 30% of its area (Fig. 3.16). The main polluters are Moscow Oil Refinery (40,000 t/year), thermal power station (5000 t/year), motor producing plant (700 t/year) and Lyublin- skiy foundry-mechanical plant (600 t/year). Of secondary importance are Electropribor plant, reinforced concrete producing plants, motor services, parkings (40), warehouses, gasoline filling stations, etc. In 1995, the total emission of pollutants from motor transport was nearly 13,000 t/year. Such a high technogenic impact exerts a very unfavorable effect on the environment and health of the population of the region (About the Status.1996). The Lyublino-Pererva industrial zone has a well-expressed concentric structure with industrial enterprises forming some kind of core. They are sur¬ rounded by motor and railway transport services and warehouses. The third ring is formed by residential areas with “embedded” administrative and com¬ munal-municipal buildings and educational institutes. Of the total area of the industrial zone (nearly 267 ha), industrial enter¬ prises occupy 134 ha. The rest of the area is under abundant warehouses, ga¬ rages, motor services, gasoline filling stations, a trolley-bus park, a fire serv¬ ice, etc. The major sources of pollution are situated in this part of the indus¬ trial zone. There are also shops, a supermarket, markets, educational institutes, living houses, including dormitory, military barracks, and a sport ground. From one side, the industrial zone borders the residential area. From the other, it borders the Moskva River. In fact, the territory of the industrial zone is an integral anthropotechnogenic complex. The industrial zone and adjacent areas are located on the 2d terrace of the Moskva River. Parent materials are sandy and loamy deposits overlaid by thick technogenic deposits. The latter arc presented by the mixture of sands, rock debris, and loams with addition (up to 50%) of stones and fragments of bricks, concrete, asphalt etc. Their thickness varies from 1.5-3.0 to 6-7 m. Topography within the industrial zone was leveled, and natural plant as¬ sociations disappeared. The territory became spatially heterogeneous in ac¬ cordance with the land-use pattern.
3.5.2.1. Atmosphere The composition of the air above the industrial zone is determined by its close location to other industrial zones. Domination of western winds provides the additional air pollution. Emission from thermal power stations is the main cause of atmospheric pollution with nitrous dioxide, sulfiirous anhydride, mazut, ash, etc. They af¬ fect the area within a radius of several to tens kilometers because of the large volume of emitted pollutants (Table 3.32). Table 3.32 Concentrations of pollutants in the air (mg/m3) and contribution of individual sources Substances Lublino-Pererva industrial zone Kuryanovo industrial zone Roads Other sources The sum of all compounds, 14.923 1.304 6.46 9.292 including: aj2o3 0.035 n/d n/d 0.010 v2o5 0.576 n/d n/d 0.314 Fe203 5.760 0.023 n/d 0.090 Mn 0.581 0.002 n/d 1.248 Сг (VI) 0.948 n/d n/d 0.411 N02 1.586 0.353 5.20 3.896 S02 0.147 0.009 n/d 0.298 CO 0.668 0.043 1.26 0.035 HF 0.003 n/d n/d 0.030 Xylol 0.126 n/d n/d 0.063 Methylmercaptan n/d n/d n/d 2.2 Mineral oils 0.225 0.002 n/d 0.045 Mineral dust with Si02 content >70% 0.131 0.261 n/d 0.071 Mineral dust with Si02 content <70% 1.458 0.162 n/d 0.432 Dust on trees 2.560 0.428 n/d 0.025 Contribution of separate sources to the overall con¬ centration of pollutants (%) 46.7 4.1 20.2 29.0 Mote: n/d is not determined. The effect of the emissions caused by motor transport on the state of the atmosphere is strong. MACs of C02, N02, phenol, and ammonium were ex¬ ceeded by more than five times. Here the index of total accumulation (ГГА) of heavy metals estimated by their content in snow is very high (>256).
Dust transfer affects atmospheric pollution in different ways. Thus, as¬ phalt, which covers 27% of the industrial zone, “redirects” 0.9657 t dust per year into the atmosphere. The surface of roofs (33% of the industrial zone) produces 0.9451 t dust per year. The surface of open (without a turf layer) soil is the main contributor to dust pollution of the atmosphere (2.5499 t/year). Vegetated areas (23% of the area) are not significant dust producers (0.0047 t/year). Totally, the industrial zone produces 4.47 t dust suspensions per year. Their mineral part is made up by toxic compounds. We also made an attempt to roughly estimate the annual weight of dust and the content of heavy metals in it produced by the Lyublino-Pererva industrial zone. The to¬ tal input of heavy metals with dust into the atmosphere is nearly 13 kg zinc, 14 kg lead, 0.8 kg chromium, 0.7 kg arsenic, and 10 to 40 g nickel and cop¬ per. In addition, dust contains nearly 3% С and 14% CaO. 3.5.2.2. Surface and Ground Waters The surface runoff is very strongly polluted with Pb, Cu, Zn, Co, and Cr at more than a half of the area. Concentrations of the following materials exceed their MACs by more than two times, suspended material (22 to 30 mg/I), synthetic surface-active substances, detergents (0.2 to 0.3 mg/1), and petro¬ leum products (up to 0.9 mg/1). Biological oxygen demand is 3.9 to 12.4 mg/1. Concentrations of nitrogen, ammonia, phenol, formaldehyde, and cyanide are close to the standard values. The pollution of bottom deposits of the Moskva River with chemical ele¬ ments is estimated to be 64 to 128 units according to ГГА. Such high pollution threatens the urban environment, since it is partly located within the catchment of the Moskva River. The surface waters discharge direcdy into the river, so causing its greatest pollution (data of the Lyublino area). This situation may be aggravated in future because the whole territory of the industrial zone is within the limits of a predicted rise of the groundwater level by more than 3 m. Presently, the total concentration of dissolved mineral salts in river waters near the industrial zone increases (1 to 1.5 g/1). 3.5.2.3. Vegetation Dense housing, which is typical for this industrial zone and abundant w are¬ houses require many roads and maintain intensive traffic. This significantly reduces the vegetated area.
The quality and state of grasses, shrubs, and trees are very poor. Open lawns or partly vegetated area of the industrial zone make up 23%. This is primarily the area around educational buildings, dormitories, and houses. Vegetation covers small plots (0.01 to 0.1 ha). Most growing trees have evident features of damage: crown thinning, hol¬ lows, bole deformations, dry branches, leaf damage, etc. The state of tree stand consisting of maple, poplar, and linden is unsatisfactory. The primary reason is generally poor ecological situation, poor management and the absence of mineral and organic fertilizers. Dead leaf biomass is toxic because of the high content of heavy metals. The absence of soil animals and destruction of fallen leaves left on the soil surface result in the formation of a thick litter layer that prevents grass de¬ velopment. The absence or poor development of the grass cover is also due to a strong disturbance of soils and dumping of the area. On an average, the grasses cover 20 to 40% of the area. Their composition is dominated by ruderal species: wormwood, plantain, burdock, knotweed, coltsfoot, etc. Most enterprises do not meet the standards of the area under vegetation, that are 20% for industrial area and 10% for enterprises with dense housing and sanitary-protective zones. 3.5.2.4. The Status of the Soil Cover Presently, territories with natural soils are absent within the Lyublino- Pererva industrial zone. Urbanozems (soddy-urbanozems and industrizems) occur on the most vegetated patches, while urbotechnozems are restricted to strongly disturbed open surfaces and moved substrates. In addition, scalped urbanozems arc found. Soils of the industrial zone are characterized by heterogeneous and tuibated profiles, elevated stoniness, high dust content in surface layers, and sandy to loamy texture. Water-physical properties of soils vary throughout the whole area. This is due to installation of an engineering-communication network, which provides a higher temperature compared to natural objects and causes appearance of voids in grounds. Throuhout the area of the industrial zone, soils are chemically polluted (Table 3.33). Concentrations of almost all heavy metals exceed their standard val¬ ues. The excess is the highest for copper, zinc, and nickel. Therefore, according to these compounds, this area can be considered as a geochemical anomaly.
Table 3.33. Chemical properties and bulk contents (mg/kg) of heavy metals and arsenic in surface horizons of soils, Lyublino-Pererva industrial zone Location. Soil c, % рНка CEC, cMkg1 Cr Мл Ni Cu Zn As Pb Rb Sr Zr Area near ga¬ 1.55 7.4 10.1 365 1707 92 350 1241 33 209 15 <3 153 rages, center of the industrial zone. Industrizem Square near the 2.06 6.2 14.7 116 570 32 66 290 14 57 45 107 160 entrance to the foundry-mecha¬ nical plant Urbanozem. Residential area 5.56 6.6 16.52 N/d 917 75 369 278 37 10 42 196 227 near the indus¬ trial zone. Urbanozem. Kindergarten, 1.43 6.9 25.1 92 726 19 53 332 18 56 132 260 278 300 m from the industrial zone. Urbanozem. Square near the 6.24 6,7 21.9 144 735 37 106 482 12 78 61 169 166 main canteen. Urbanozem. Dust from as¬ 3.19 7.3 27.7 184 947 28 78 2963 15 313 36 56 270 phalt, center ol industrial zone Warp from ca¬ 1.44 7.2 n/d 455 375 44 40863329 28 470 41 186 222 nalization. Estimated alb' "able bulk concentrations n/d n/d 20 33 5 2 32 n/d n/d n/d Note: n/d is not determined. Dust that is deposited on artificial surfaces has the highest content of heaw metals. It is maximal for zinc (128 MACs) and lead (15.7 MACs). The unvegetated open surface that occupies 18% of the industrial zone (mainly around plants, garages, parkings, etc.) strongly threatens the surrounding ar¬ eas because of dust deflation and translocation of polluted surface deposits to
neighboring areas. The content of heavy metals in them is determined by the amount of deposited dust and composition of original and filled grounds. Besides that, it is established that the surface runoff takes away copper (4086 mg/kg), zinc (3329 mg/kg), and lead (470 mg/kg). The accumulation of these metals is evidenced by the following fact. Sediments collected from a surface runoff collector before it entered the industrial zone contained these metals in amounts by 30, 10, and 4 times less, respectively, than their content, when the collector passed a catching area of the industrial zone. When considering accumulation patterns of pollutants in different natu¬ ral-anthropogenic areas, we compared the content of heavy metals and arse¬ nic in soils of a residential area, the border of the industrial zone, disturbed grounds without a turf layer and managed (planted) areas of the industrial zone. Cation exchange capacity (CEC) of urban soils (10 to 25 cM(+)/kg of soil, everywhere exceeds that of natural topsoils roughly estimated as 5 cM(+)/kg of soil). The composition of the CEC is dominated by Ca (above 70%) followed by Mg and K. The Na content is low everywhere. Such a high CEC favors the resistance of soils and grounds to geochemical impact and binding of heavy metals. Thus, the following features are the most characteristic ones in the L\-ublino-Pererva industrial zone: • Artificial covers and areas under houses dominate the land surface They contain more heavy metals in the surface dust layer subject to de¬ flation. Hence, these areas are the source of secondary pollution of the atmosphere and surface waters. • Urbanozems of the residential area adjacent to the industrial zone have the lowest mean content of heavy metals among all categories of sur¬ face bodies. • The highest content of heavy metals is in humus-enriched industrizems managed for more than 40 years and having no additions of fresh ground. • Concentration of heavy metals in urbanozems rather depends on the land-use pattern than on the location of the sampling site relatively to the source of emission.
3.6. Conclusion The Moscow region is one of the largest urbanized areas in the world. Here nearly 16 million people (almost one-tenth of Russia’s population) live at 0.3% of the country's area. Moscow is the most northern megalopolis of the w'orld. In the last years, ecological problems have aggravated as reflected in the state of the environment, including the soil cover and, hence, the health of ur¬ ban population. The obtained results proved that the ecological situation in the city is very difficult. It causes now and, as predicted, will cause some ad¬ verse consequences, that will affect the physical and mental health of men. Among the most acute ecological problems troubling the population are the high content of exhaust gases in the air, the antisanitaiy state of the city territory and the shrinkage of the planted area and of the protective belt of forest-paiks. The major reasons of indicated ecological problems are pollution caused by motor transport and industrial enterprises. The natural soil cover is absent от 85 to 90% of the city area. More than 30% plantations located within the city are damaged and degraded. Also, some areas are waterlogged. Presently, more than 20% of the cases of illness in the city occur be¬ cause of the deteriorated environment. One of the major negative processes is the strong chemical pollution of the natural environment that also bears a bacteriological threat. This increases the sick rate of children and adults, for example, by 20% from 1985 to 1990. Thus, the occurrence of cardio¬ vascular diseases increases by 1.5 times. The contribution of environmental pollution, to the deterioration of hu¬ man health is estimated to be 20 to 30%. Therefore polluted areas are char¬ acterized by a higher occurrence (40 to 60%) of bronchial asthma, bronchitis, tonsillitis, and other respiratory diseases. The demographic situation is also very unfavorable. Presently, among the largest cities of the world, Moscow is just on the 6 2d place by birth rate, on the 81st place by natural increment, and on the 60th place by surviving of children under one year. In the capital of Russia, the children death rate is two times greater than in London, Rome, and Toronto and by three times greater than in Tokyo and Madrid. The average life expectancy of moscovites is by seven to eight years less than that of inhabitants of Vienna, Paris, and Tokyo
CHAPTER 4 Adverse Environmental Processes and Their Effect on Soils and Soil Cover in Moscow Adverse ecological processes in the urban environment are processes that essentially hinder (prevent) urban soils to perform their ecological functions. At the same time, these processes essentially affect the modem status of ur¬ ban soils. A significant part of Moscow is subject to the action of adverse proc¬ esses that affect the ecological status of the soil cover, properties and func¬ tions of soils. According to predictions of ecologists, their impact will inten¬ sify' over time. At the same time, always there is one process that dominates on a particular category' of urban lands. 4.1. Processes that Adversely Affect Ecological, Sanitary, and Hygienic Status of Urban Lands 4.1.1. Mechanical (City Building) Processes Increase in the proportion of sealed and decrease in area under vegetation. Mam causes of the shrinkage of the vegetated area in city' are its use for needs of the city' economy as well as "natural" break-up of stands under the effect of the urbanogenic stress and poor management. The other factors are excessive recreation; poor conditions for plant development (poor air, soil, and water
quality); poor management of plantations (untimely thinning of stands, ab¬ sence of agrotechnical measures, etc.); and improper policy of city develop¬ ment, including poor control for land use. The soil cover exerts a multifunctional “healing” effect on the urban en¬ vironment. This effect decreases (and eventually disappears) as the propor¬ tion of sealed soils increases. A good example are residential areas in the Central Administrative Region of Moscow, where the vegetated area is less than one to two square meter per inhabitant. During the reconstruction of the city center, the area under vegetation should be increased at the cost of un¬ sealing paved areas. However, sealing of the lands of public use often provides the effective control of the sanitary status of the area. Although, unfortunately, it is tech¬ nologically unavoidable. Therefore, individual approaches are required when acquiring and re¬ claiming uncultivated unused areas, abandoned lands, dumps and quarries. Sometimes sealing of land parcels will be the optimal solution for preventing environmental hazards. Tipping and cutting of natural soils and deposits. In the city, humans modify the land surface to make it more suitable for building, since they want to have the optimal declivity of roads and areas. Moscow mainly has a dis¬ sected topography and is situated along waterways of the Moskva River and its tributaries. During the long history' of the city7, a thick layer of anthropo¬ genic deposits has been formed. It includes the cultural layer and layers of tipped rock for building on low sites, gullies, and waterways of small rivers. The greatest changes (removal of natural soils and land filling) are observed in the most dissected southern part of the city They result in surface leveling and filling of gullies and ravines. The layer of technogenic deposits is up to 20-m thick. Static and dynamic impacts, especially the rise of groundwater table, cause significant subsidence, deformation of buildings, and changes in the land surface. This changcs water and temperature regimes of soils and affects their humus status. Dumping of soil surface. Dumping is the deposition of construction and household wastes on the surface. Wastes can be the source of pollution be¬ cause of decomposition and leaching of toxic compounds.
Modem building is a major contributor to surface pollution of soils and deposits. In the city environment, it is the second factor in regard to the amount of produced solid waste, residues of construction materials, and min¬ ing rocks. The area under construction is generally dumped. Pollutants from construction areas can spread further on neighboring areas. Thus, improper storage of construction materials is a source of dust. Typically- waste, often toxic, is partly burned on site, while the rest is dug in ground, so predeter¬ mining future pollution of soils and water. Within the limits of Moscow, 25 million to 28 million tons of ground are ex¬ cavated every year. Most of it is transported to neighboring areas, while the rest is used for leveling construction sites. Waste left after construction, reconstruction, and major repairing of buildings contributes to pollution of soils and sediments. Significant amounts of heavy metals are concentrated in paints that coat colored brick, fallen plastering, etc. Thus, they contain zinc, lead, cadmium, copper, and chromium in the amounts by 15 to 60, 20 to 35, 10 to 15, 6 to 10, and 5 to 10 times higher, respectively, than their background contents in soil. Burying of plas¬ tic material increases the content of cadmium, while remains of ceramics increases the content of zinc, chromium, and copper. Burying of paper raises the concentra¬ tions of zinc, lead, cadmium, and chromium. Moscow annually produces more than 2,3 million tons solid household wastes and 3,6 million tons industrial wastes. These amounts increase by 3.1% every year. Studies of dumped sites and neighboring areas show that the former significantly pollute the environment around them. 4.1.2. Physical Processes Water (linear and gully) erosion and deflation. Engineering and building activities of humans in cities accelerate erosion, which commonly results in poor planning and improper functional arrangement of the urban environ¬ ment. Erosion is one of the most important processes in the city, since it oc¬ curs over large territories and causes strong damages. Within the area of Moscow, there are more than 15 plots with deep landslides (down to 100 m) and nearly 200 plots with surface landslides (Osipov, 1994). Deep landslides are observed along 12% of the length of the Moskva River valley. Surface landslides occur in valleys of the tributaries. Their
number has been doubled for the last 10 years because of reclamation of new lands. Poor management of surface and storm runoff on compacted plots with slopes steeper than 1 to 1.5° and leakage from water pipelines, canalization, and heating communications form hollows and erode the top humus horizon of soils. Water of streams also carries suspended material and pollutants. These waters accumulate in natural depressions and cause waterlogging of building basements. Strong erosion often develops on unvegetated wastelands with a disturbed soil cover, including areas of water-protective zones and lands around gullies with slopes greater than 3 to 5°. The development of ero¬ sion is especially dangerous on dumps that contain toxic compounds. Shift of water balance. The term waterlogging implies the rise of groundwater to a layer of 0 to 3 m below the soil surface, due to leakage from water pipelines and canalization, seepage from ponds, as well as because of irrigation, creation of artificial catchment areas, and deterioration of natural drainage ways. The latter is due to ground compaction and surface leveling after filling of gullies and valleys of small rivers and streams. Waterlogging is a noticeable phenomenon in the cities of Russia since the 1950s. Presently, nearly 960 cities, or almost 90% of Russia's cities, are subject to waterlogging. Thus, the proportion of waterlogged area in Arkhan¬ gelsk is 100%. It is 80% in Astrakhan', St. Petersburg, and Tula. Waterlog¬ ging provokes the development of landslides and creeps on slopes and dis¬ turbs the organic profile of soils. In addition, gleying develops within the soil profile. Waterlogging changes the chemical composition of the groundwater and the ground resistance. The mapping of waterlogging in Moscow shows that its intensity' de¬ pends on the land-use pattern, geomorphologv of the surface (watershed, slope, terrace, and flood plain), and rock texture. Over the last 20 years, the level of the groundwater has been gradually rising in western, southwestern, and northwestern parts of the city. The rate of the groundwater rise ranged from 0.05 to 0.4 m/vear. In the eastern part of the city, waterlogging occurs at 80% of the area. On the average, it affects up to 40% of the area of Moscow (Fig. 4.1). In residential areas, in most cases, waterlogging exerts the negative effect: basements of houses become wet and subject to destruction. Mesophvtic plant communities become replaced by the hygrophytic ones. In addition, the soil profile
becomes less permeable for water and air. This decreases the productiv¬ ity and restricts the envi¬ ronmental functions of soils. Dangerous con¬ sequences of waterlog¬ ging are found at the territory of industrial zones, heat and electric power stations, ware¬ houses, transport serv¬ ices, roads, railways, etc. Because of water¬ logging chemical pol¬ lutants become dis¬ persed on greater areas by groundwater flows. Urban lands are subject to drying, since their stony surfaces have a peculiar tem¬ perature balance, and unfavorable hydro- geological conditions (karst, quarries, mines, highway installations, and sewage water canals). They split up the original land surface, disturb water migration in soil and cause degradation of vegetation and destruction of the turf layer. As a result, the total productivity of the ecosystem decreases, while the hazard of wind erosion for open, uncovered with turf and unvegetated, surface increases. This was recorded on unused and waste areas, quarries, etc. Compaction within the rooting layer. Planted plots in the city are rela¬ tively unstable to human impact. Soil compaction due to trampling produces the most significant impact on urban plantations. Strongly compacted soils are characterized by vegetation decline. Fig. 4.1. Scheme of waterlogging. (About the Status, 1994). 1—waterlogging in 1993; 2—forecast (by the year of 2010).
Trampling and destruction of the turf layer change the surface runoff. All this causes degradation of the ecosystem or deteriorates its suitability for recrea¬ tion. The soil fertility decreases due to changes in the water and air regimes within the rooting layer. Changes in the temperature regime of soils. Warming and thermal shifts. In summer and winter, the territory of Moscow was scanned with in¬ frared thermal aerial monitoring. Its results showed that areas of temperature anomalies (temperature increase by 10 °C) are linked to industrial objects, undeiground communications, and zones of intensive leakage from under¬ ground water-supply communications. Temperature anomalies increase the growing period and accelerate melting of the snow cover. This affects the temperature regime of soils. Thermal shifts develop on densely built areas and on the open surface sealed with asphalt and concrete. Stronger warming of soils and deposits makes them excessively dry and changes their physical and mechanical properties. Thermal fields in the city center are due to leakage from undeiground water collectors. Temperature anomalies within the flood plain of the Moskva River evolve because of a discharge of the industrial and household wastes. 4.1.3. Biological Processes Exhaustion and disturbance of the organic profile of soils. Exhaustion and disturbance of the humus layer results from trampling, re-planning, erosion, plant cover degradation, airborne and fluvial chemical pollution, and typically discontinuous management of the area. This process reduces the rooting layer, which can be also restricted by some subsoil materials (construction concrete plates, pipes, etc.). On lands of public use, this process can be enhanced by chemical pollu¬ tion, which causes further degradation of the vegetation. In forest-parks and parks, the organic profile of soils is less disturbed. How¬ ever, trampling, dumping, erosion, and chemical pollution cause its degradation on sites with a disturbed humus horizon. All this limits the soil resilience. Reduction in the biodiversity of soil organisms, changes in the struc¬ ture of microbial communities, and development of infection with patho¬ genic organisms. Cities are characterized by a strong reduction in all compo¬ nents of biota compared to natural ecosystems. The soil biomass in urban
ecosystems decreases because of lower number of living organisms, simpler structure, and worse productive capacity of biota. All urban soils are characterized by a lower biodiversity of higher and lower organisms. At the same time, pollution with chemical and biological compounds can be accompanied by infection of soils with alien microorgan¬ isms, including pathogenic species. These processes also threaten neighboring areas, when pathogenic microbes spread with surface runoff and air. This is especially true for aquatic and semi-aquatic landscapes. To eliminate this threat, the territories should be subject to disinfection and sanitation. The fer¬ tile layer of the polluted soil should be replaced. The surface runoff should be managed and cleaned. 4.1.4. Chemical Processes Contamination of the urban ecosystems by regular and accidental emis¬ sions in the city and by the global mass transfer. The urboecosystem is characterized by pollution because of the accumulation of strong toxicants, radioactive compounds, pesticides, and organic and inorganic toxic com¬ pounds on the soil surface, in soil, and in other ingredients of soil- geochemical landscapes. Urban landscapes are subject to the impact of gases emitted into the atmosphere and are affected by the discharge of liquid and solid industrial wastes to areas around industrial zones. As a rule, this drasti¬ cally changes fauna, flora, soil cover, and productivity of the whole ecosys¬ tem. The effect of these adverse processes was thoroughly studied (Geochemistry of the Environment, 1990; Obukhov et al., 1988, 1989, and 1990; Ecogeochemistry..., 1995; Thornton. 1991; and others). Pollutants get into residential areas and lands of public use through regular contamination as well as through accidental emissions and the global mass transfer. Soil pollution correlates to strong pollution of the air and often of the aquatic environment. It is also directly connected with the status of vegetation and human health. Wastelands, dumps, and quarries are subject to various kinds of chemi¬ cal pollution. The threat of pollution sometimes increases if these lands are used for other purposes, for example, for house building. Pollution from these areas may spread on neighboring areas through soil, water, and air. Somewhere in cities, the level of ionizing irradiation exceeds the allow¬
able limits. There are three main sources of irradiation in the city. (1) Anthropogenic (living houses, asphalt covering of roads, and medical procedures). (2) Technogenic, the most dangerous source (industrial and military plants, research and medical institutions). (3) Secondary sources of radioactive pollution (buried waste, equipment, and by-products). The main consequences of exposure to radiation are the increase in sick rate, mutation frequency, and mortality of the population. Changes in soil acidity and alkalinity. In residential areas, both acidifi¬ cation and alkalinization of soils negatively affect soils themselves and aboveground parts of plants. Owing to its buffering capacity, soil does not experience adverse consequences under insufficient changes in soil reaction. In old residential areas (the center of Moscow), most of the soils are alkaline and enriched with calcium carbonate. As the strength and duration of impact increase, soil degradation develops. The changes in soil properties, namely structure, elementary composition, and physicochemical properties, depend on the humus status of soils. Soil acidification develops in low-humus soils on glaciofluvial deposits, which have a low cation exchange capacity. Acidification and alkalinization locally develop on lands of public use, industrial zones, warehouses, motor services, and roads. The intensity' of the process depends on the local sources of acid emission. • • • Generally, adverse processes that develop in urban soils are very poorly studied. For example, dangerous biogeochemical processes and phenomena are brought into existence by technogenic (thermal, electromagnetic, and chemical) fields of industrial cities. “Electromagnetic smog” directly influ¬ ences health and genome of humans. Wandering currents, warming, wetting, and salinization of soils and deposits sharply accelerate the chemical and bio¬ chemical processes and the mobility of iron and aluminum in soil. Technogenic geochemical fields that develop in surface layers, including soil, accelerate mutations of microorganisms threatening to human health. According to the World Health Organization, this has given rise to nearly 20 new viral infections during the last 30 years. The impact of these fields on processes and properties of soils is poorly studied.
4.2. Conclusion The ecological state of the soil cover is not affected just by one factor but al¬ ways by a combination of factors. Taken together they produce in stronger consequences than taken single because of their synergism. Along with soil processes, adverse processes occurring in air, water, and geological media can deteriorate the state of urban lands. The complex of measures controlling the adverse processes and for lo¬ calization and elimination of their consequences includes: (1) Elimination of causes of adverse processes or decrease of their intensity (e.g., introduction of new technologies and improvement of cleaning units can decrease the total emission). (2) Elimination of consequences of adverse processes (e.g., complete re¬ placement of strongly polluted soils and vegetation). (3) Adaptation to adverse processes through the increase of the urban sys¬ tem resilience to the human impact (e.g. planting of dust- and gas-tolerant species, increase of the productive layer). (4) Reduction or localization of adverse consequences of processes (e.g., establishment of sanitary and protective zones and other planning de¬ cisions). The most efficient are measures of the 1st group. They eliminate the sources of adverse processes. At the same time, these measures are the most expensive, so they hardly can be used. Measures of the 2d group are also very' expensive and should be applied in the most ecologically unfavorable zones. Measures of the 3d and 4th groups are a compromise between economical and ecological interests and are most often applied. Presently, measures for cardinal reoiganization of environmental activi¬ ties of municipal services (resource-saving, low-waste technologies and equipment, up-to-date cleaning units, planning solutions, e.g., condensing of the build-up, especially of industrial areas and warehouses, acquiring of wastelands, etc.) are hardly possible. Nonetheless, only measures of this group can principally improve the state of urban lands. Therefore, they should be considered as the strategy of land-use development. All other measures are tactical. Among them the following measures can be mentioned:
elimination of unauthorized fireplaces and dumps, garbage removal, control for unauthorized emissions, discharges, unauthorized land use. The present-day status of urban lands requires comprehensive sanitation (improvement of sanitary conditions and reclamation) of the most polluted and merely disturbed lands and simultaneous prevention of deterioration of relatively undisturbed lands. The special measures on protection should be applied (listed in order of the priority of protection): (1) occupied by sensitive recipients: hospitals, schools, nurseries, etc.; (2) heavily populated areas; (3) occupied by valuable cultural and architectural objects. The following measures are the most important ones for the prevention of adverse processes: • Reduction of emission from motor transport (wide complex of meas¬ ures can be applied, which ranges from administrative restrictions of the use of private transport to development of public transportation, planning decisions, and introduction of electric transport). • Planting and sanitation of areas adjacent to main roads. • Reduction of industrial emission (primarily through installation of effi¬ cient cleaning units and control for their exploitation). • Planting (at least to a degree indicated by existing standards) of resi¬ dential areas in the city center (including “unsealing” of paved soils for planting), proper management of plants and increase of soil fertility. • Separated discharge and cleaning of the surface runoff, especially that from industrial zones. Measures on environmental adjustment of the land use within the city limits should be combined with measures on its improvement outside the city. Thus, in Moscow, the protective belt of forest paries requires principal recon¬ struction, since 47% of its area are built and 14% are occupied with agricul¬ tural lands. More than 200 cattle farms should be discharged or removed from the sanitary zone of city water supply. The same should be applied to country houses that were constructed within the water protection zones during the last years.
CHAPTER 5 Microbiological Properties of Soils in Moscow Among different components of the urban environment, a special interest of soil scientists and ecologists is attracted to soils, although their biological and microbiological properties remain poorly known. Each element composing the urban soil cover has so significant and specific functions that has to be treated individually. This is important if to understand the soil as a medium, in which live the organisms that perform most of the biochemical processes in nature. Knowing the specifics of biological properties of individual urban bi¬ otops, we can establish their interrelationships, understand the significance of each element of the urban soil cover for its functioning as a whole, and inter¬ actions between them. For this purpose, we should view not only general regularities of ur- banogenesis, which are similar for the whole city, but also regularities specific for a particular landscape-geochemical province, where the city is located, as well as its age and the degree of city development. The use of microbiological methods can reveal both general and specific regularities of changes in the urban environment versus the natural ones. Common urbanogenic impacts such as motor, transport, pollution of soils with petroleum products, sodium and potassium chlorides, and enrich¬ ment in nutrients and oiganic matter affect the microbial population of soil. Therefore, the microbiological status of urban soils can be used for the char¬ acterization of urban territories.
The effect of urbanogenic products on the urban environment is com¬ plex. Therefore, usually, its general estimate is obtained. However, some bio¬ logical properties of urban soils make it possible to study its individual com¬ ponents. Along with information on the indicative role of microoiganisms, re¬ searchers are primarily interested in how can microorganisms adapt and pre¬ serve their viability in a new anthropogenic environment and how can humans withstand destructive urban effect? 5.1. Indicative Properties of Soil Microorganisms Microorganisms remain viable in the urban environment if their natural niches have been preserved, especially when a substratum they prefer is available, or if they are adapted to the properties of urban soils. Sometimes the latter surprisingly correspond to the main needs of microorganisms: neu¬ tral pH, excess of nutrients, organic matter, and heavy metals. In both cases, they can be used as indicators of the status of urban environments. Further¬ more, this is referred not only to saprotrophic but also to pathogenic microor¬ ganisms. To predict the development of pathogenic microorganisms in the urban environment, especially when considering its soil cover, it is very important to know their natural focuses. As shown by Maksimenkova and Karpachevskiy (l 985), properties of natural focuses of infection are similar to those of urba¬ nozems. Therefore, they can be used for sanitary' and hygienic monitoring of the urban environments, natural and urban focuses of leptospirosis, pseudo- tuberculosis, intestinal yersineosis, and other diseases occurring under similar soil conditions. (1) Both natural loci of infections and the area of Moscow have a heteroge¬ neous soil pattern with soils of depressions as a component. (2) In both cases the soil reaction is nearly neutral (7.5) that promotes the growth of leptospires and yersinia. (3) Soils favorable for pathogenic microflora have high base saturation that maintains the pH at the constant level optimal for these bacteria. (4) Soils are rich in organic matter (4.9 to 24.1%).
The last is especially important for pathogenic bacteria that can survive in soils of depressions. Therefore, such soils, for example, natural silty-bog soils, are the greatest source of infection. The urbanization of the territory typically started with the development of motor transport that polluted soils, particularly with heavy metals. How¬ ever, it is widely known that many soil microorganisms are resistant to heavy metals (Hemida et al., 1997). For example, soil nitrogen-fixing bacterium, Azotobacter, can accumulate lead in the amount of up to 300 mg/g of dry biomass (Gromov and Pavlenko, 1989). Azotobacter is a bacterium adapted to anthropogenic changes in the environments (Skvortsova et al., 1997). This bacterium is highly ecologically plastic and can survive in soils during dry pe¬ riods by forming resting structures—cysts. Its cysts, when formed directly in the soil, have a higher resistance to lower soil moisture compared to those formed on nutrient medium in laboratory. The ecological plasticity of Azoto¬ bacter is also attested by the feet that this neutrophilic bacterium may de¬ velop at low soil pH in the presence of available phosphorus and carbon. Azotobacter is re¬ sistant to components of deicing salts, particularly to sodium chloride. In ad¬ dition, there is a direct re¬ lationship between its de¬ velopment and the NaCl content in a medium within a certain range of its concentrations (Page, 1986, Fig. 5.1). Beside aforemen¬ tioned biological peculi¬ arities of Azotobacter, there are other, very spe¬ cific reasons why it is found in soils of strips between tracks with intensive traffic (Mendeleeva street, Moscow). Lawn grasses grow well on strips, when their surface is covered with dust or natural material, while, in turn, grasses promote the development of rhvzospheric bacteria. On a track-dividing strip in Moscow, algae had the low species diversity of all orders. Yellow-green O) E с 4) о k_ Q. *55 о NaCl Fig. 5.1. Na-dependent growth of Azotobacter chroococcum (Page, 1986).
algae were absent, and the soil was dominated by the most resistant algae of the genera Phormidium, Lyngbia, Plectonema, Chlorococcum, Chlorella, and Chlamydomonas (Yakovlev, 1997). 5.2. Peculiarities of Microbial Communities in Urban Soils Oil pollution typically accompanying urbanogenesis changes the composition of soil microbial communities, which become dominated by Rhodococcus— bacteria close by its properties to actinomycetes (The Prokaryotes, 1992). The increased amount of these bacteria relatively to the reference may attest to a soil pollution with oil. The high amount of Rhodococcus in oil-saturated chestnut soils of the Zavolzhie (Transvolga) region has been established by Prof. Krasil'nikov in 1938. Rhodococcus can be easily accounted in soils polluted with oil by reddish orange color of colonies and by the typical living cycle of these bacteria. The fact that the Rhodococcus uses hydrocarbons as a growing substratum was noted by Nesterenko et al. (1988). Thus, the soil of a terminal bus stop near Luzhniki (Moscow) was also dominated by red- pigmented Rhodococcus. The amount of these bacteria was up to 90% from that grown on a cultivation medium in the laboratory', while their amount in a reference soil on the nearest lawn was 1%. The high content of Rhodococcus can reflect to what extent these bacteria clean soil from petroleum products (Yagafarova and Skvortsova, 1996). Accumulation of soluble salts is a widespread phenomenon in urban soils. That is why, some microoiganisms, especially spore-forming bacteria, can sustain high concentrations, for example, of sodium chloride. Thus, bac¬ teria, when isolated from soils of residential areas, had a higher salt resistance (they developed in 7% NaCl) compared to a bacterial population isolated from a soddy-podzolic soil of the forest-park that could withstand only 2% NaCl. It was also established that only oligotrophic soil bacteria could sur¬ vive in generally highly polluted soils of Moscow. Their growth in natural soils is oppressed by a rapid development of bacteria nonresistant to the hu¬ man impact. Soil alkalinization is another feature of the urban environment that pro¬ motes development of alkali-loving or alkali-resistant soil microorganisms such as actinomycetes, some bacteria, and shell amoebas.
The dominance of microorganisms in urbanozems can be observed at the level of groups, species, and subpopulations. It indicates two phenomena: the ability of the microbial complex to adapt to the altered environment or the formation of a new, so-called technogenic community capable of Living in anthropogenic environments. Actinomycetes are a good example of alkali-loving bacteria that domi¬ nate in urban soils. Thus, numerous actinomycetes were found in a strongly polluted soil at the territory of the Southwestern Administrative Region of Moscow (Table 5.1). Their amount is comparable to that found in a steppe chestnut soil. From the ecological point of view, the increase in the amount of actinomycetes is important, since they promote decomposition of the organic matter in urban soils. The increase in number can be accompanied by a higher species diversity of these microorganisms. This approaches their structure to that found in more southern soils, so adversely affecting some habitats in the southern taiga. The high taxonomic diversity of actinomycetes revealed in the substrates of playgrounds in Moscow threatens the health of humans, especially children. It should be noted that the microbiological status of playgrounds is hardly studied (Harris, 1991). Actinomycetes, producers of allergens, can also accumulate in municipal ventilation systems (Ahearn et al., 1991 and 1992). The other allergenic compounds (mycotoxins) are pro¬ duced by microscopic fungi, particularly some species of the genus Asper¬ gillus (Summerbel, 1994; Marfenina et al.. 1996). Decomposing municipal wastes also bear the risk for human health (Umge-Asschenfeld, 1993; Chiu et al.. 1996; Filip and Smed-Hildman, 1991). Kulicheva and colleagues (1996) proposed the method for estimation of the hygienic status of the urban environment and the degree of its pollution. If a microbial complex under consideration has the proportion of enterobacte- na and Rhodococcus higher than 13 and 2%, respectively, then the sample of soil, plant leaf (philloplan), and plant litter belong to the urban area. Since soil dust always was the apparent source of human diseases, this has triggered the investigation of this problem. In the end of the 19th century', the data accumulated attested to the relatively fast decline of the most patho¬ genic bacteria in soil. It was found to be controlled by the specifics of soil properties and pathogenic species. Later, this was confirmed by the data of Mishustin et al. (1979). How¬ ever, it is very difficult to assess various combinations of soil conditions in the city, both promoting and preventing the development of infections.
Table 5.1. Change in the amount of bacteria in surface horizons of urbanozems in Moscow Beef- extract medium, thou/g 450 560 470 1190 2010 960 410 190 n/d Starch- ammonia agar, thou/g 65 48 52 12 120 70 13 7 n/d Вас. megaterium dissodanis СЛ 13 12 13 33 59 10 14 15 n/d 06 0 0 0 52 61 28 31 45 2000 Chapek medium b § 5? 4.3 2.1 3.2 64.2 60.0 43.1 25.0 32.0 78 0 I thou/g* I 39 12 13 140 199 51 91 195 13 Total thou/g* 903 552 403 824 835 471 351 600 0 Mobile forms (INHNOj) Cu | Pb | Cd | mg/kg | 0.5 0.2 0.4 1.2 0.6 1.1 0.6 1.3 5.2 20.0 6.0 45.0 560 85 98 76 156 13 11.0 1.1 19.9 76 37 45 20 61 247 q I Qu gr 10.5 7.5 6.0 52.8 83.3 67.0 73.5 n/d n/d X 2.4 2.7 2.3 2.8 n/d 1.4 3.5 2.3 2.3 I X 0. 5.9 5.8 6.3 7.5 n/d 7.6 7.5 8.0 5.8 Functional zone Forest-park (Vorob'evy gory Park (Fili) Park (Neskuchny Garden) Residential area Residential area Square Park Filled lawn Mixed forest (Moscow region) Pit no. Soil 18. Soddy- podzolic 25. Soddy- podzolic 21. Soddy- podzolic 13. Urbanozem 17. Urbanozem 16. Urbanozem 10. Urbanozem 9. Urbanozem Soddy- podzolic E C3 •o с о Noie: n/d is not determined.
The infection sprawl is the result of the high proportion of pathogenic bacte¬ ria in the microbial complex. However, as noticed, some saprotrophic microor¬ ganisms can also be very abundant. Urban soils of Moscow are dominated by a specific spore-forming bacterium—Bacillus megaterium, which may indicate some combinations of heavy metals in soil (Table 5.1, Fig. 5.2). forest-park park lawn residential area forest-park P31^ lawn residential area Fig. 5.2. The ratio between the relative content of Вас megaterium and the con¬ tent of heavy metals in soils of Moscow. A. Overall parameter of concentration of heavy metals (Cu, Pb, and Cd); B. Content of Вас. megaterium. Вас. megaterium is capable of the dissociation deriving two colonial- morphological variants, which are termed R (folded-surface) and S (smooth- surface) dissociants (Table 5 .1). Colonial-morphological variants of bacteria differ in their properties. For example, their reaction on changes in the envi¬ ronments are different. Predominance as a manifestation of the disbalanced development of the microbial community is also typical for other soil microorganisms: shell amoebas and algae (Yakovlev, 1997). Soils of old cloisters and palaces were dominated by shell amoebas of the genus Trine та (60% of the total amount). All studied urban soils were dominated by cyanobacteria (blue-green algae), especially of the order Oscillatoriales and had lower diversity of green algae. Among diatoms large forms prevailed. Yellow-green algae were relatively seldom found in urban soils. Thus, soil algae can characterize the type of ur¬ ban phytocenosis. In parks and squares, the composition of soil algae ap¬ proaches the zonal one and is characterized by strong development of all divi¬
sions, including yellow-green algae. Resistant representatives of single-cell green algae dominate on lawns and boulevards. At the same time, the amount of cyanobacteria and diatoms is insufficient, while yellow-green algae are not recognized. Cyanobacteria and green algae are abundant in yards dumped with household waste. The indication of technogenically polluted environments by algae devel¬ oped by Shtina (Shtina et al., 1985) revealed a clear relationship between the composition of algae and the type of human impact. Yakovlev (1997) ex¬ trapolated this approch on urbanozems of Moscow. In addition, the use of al- gological analysis will likely permit the decoding of some types of pollution on the urban territories. Algae can recover in the course of soil self-cleaning. The viability of blue-green algae on polluted sites of Moscow corresponds to that under ex¬ treme conditions (domination in chloride-sodium solonchaks affected by sew¬ age water from oil extraction). The behavior of diatoms in soils of Moscow is contradictory (Table 5.2). Perhaps, this is because, under natural conditions, they dominate in acid iron-sulfate solonchaks affected by mining water (Shtina et al., 1985), while urban soils are alkaline. The behavior of algae in the urban environment is undoubtedly different from that in their natural or nonurban habitats. However, knowing the reaction of algae to different pol¬ lutants, we can use them for preliminary biological mapping of pollution types in the city. Moscow is famous for its abundant historical monuments in the city center where soils of cloisters and manors are affected by intricate combina¬ tions of anthropogenic, historical, and natural factors. These urbanozems contain information on the peculiarities of ancient microbial cenoses in soils. Thus, urbanozems of the Rozhdestvenskiy and Zachat'evskiy cloisters are characterized by a peculiar distribution of Azotobacter (Table 5 .3) and other bacteria along the profile. At the territory of the Rozhdestvenskiy Con¬ vent, the relatively dry topsoil of the urbanozem is strongly dumped with arti¬ facts but does not contain the living cells of Azotobacter. At the same time, ancient marble foundations found in the subsoil maintain a neutral pH (6.8) and phosphorus in the amount favorable for Azotobacter in the zone of its maximal occurrence (50 to 90 cm) and below. High moisture content in the subsoil because of waterlogging of the Rozhdestvenskiy Convent with waters of the Neglinnaya River also promoted Azotobacter development.
Table 5.Z The number of algae species in soils of natural and polluted areas of Moscow Location Blue- green algae Thread green algae Single- cell green algae Thread yellow- green algae Single¬ cell yellow- green algae Diatoms Total number of spe¬ cies Leninskie gorki natural reserve (background) 15 2 18 2 4 14 55 Malinki biological sta¬ tionary (background) 1 4 23 2 2 5 37 Fili forest-park (relati¬ vely undisturbed plot) 10 2 8 n/d 2 8 33 Fili forest-park (compac¬ ted path) 2 n/d 6 n/d n/d 2 9 Square adjacent to Yusupovskiy palace 8 2 10 n/d 2 8 30 Playground strongly damped with construc¬ tion waste 12 1 8 n/d n/d 2 21 Lawn polluted with household waste 12 n/d 4 n/d n/d 3 20 Lawn near motor pro¬ ducing plant (ZIL) 5 n/d 4 n/d n/d 3 12 Lawn on highway divid¬ ing strip 8 1 5 n/d n/d 6 20 Area of gasoline refuel¬ ing station 8 1 4 n/d n/d 6 19 Source: Yakovlev, 1997. Note: n/d is not determined. Table. 5.3. Number of microorganisms in the profile of an urbanozem at the territory of the Rozhdestvenskiy Convent Sampling depth, cm Number of microorganisms, millions per gram Azotobacter, per¬ centage of cover¬ age of soil crumbs (Ashbey medium) bacteria on beef-extract agar medium bacteria and acti¬ nomycetes on starch-ammonia medium cellulosolytic mi¬ croorganisms (Hutchinson me¬ dium) 0-35 2.0 3.0 3.0 0 35-50 1.5 1.5 4.5 0 50-90 5.0 3.0 105 22 90-128 2.7 4.8 150 8 >128 8.4 6.2 150 15
Similar to Azotobacter, cellulosolytic bacteria also may indicate soil condi¬ tions that enhance the decomposition of ceUulose-containmg substrates in the lower part of the profile of a nekrozem. The peculiar combination of technogenic, historical, and natural factors in cloisters forms an "overturned" microbiological profile of the urbanozems. It is different from the gradual downward decrease in the number of microoiganisms in most of the soils of the natural landscapes that do not have a buried horizon. At the same time, in contrast to Azotobacter, other bacteria are evenly distributed along the profile (Table 5.3). Independendy on the reasons of such a profile distribution of Azotobacter and cellulosolytic bacteria, they form a pool of microoiganisms, which can be used for microbiological remediation of urban soils (Zvyagintsev, 1987). The urbanozem of the Rozhdestvensldy Convent was also had a strong spe¬ cies diversity and abundance of shell amoebas (Yakovlev, 1997; Fig. 5.3). Their abundance was by one-third higher than that in a reference site under spruce forest where the densest population of shell amoebas was found. Fig. 5.3. Number of shell amoebas in soils of Moscow and background areas according to Yakovlev (1997). (1) Undisturbed soil under linden stand (Malinki forest enterprise, Moscow oblast); (2) Undisturbed soil under spruce stand (Malinki forest enterprise, Moscow oblast); (3) The same. Disturbed soil below spruce stand; (4) Undisturbed soil. Losiny Ostrov forest-park; (5) Path, Losiny Ostrov forest-park: (7) Urbanozem. The Rozhdestvenskiy Convent; (9) Square adjacent to Yusupovskiy Palace
5.3. Some Natural Factors of Occurrence of Bacteria in Urbanozems The other specific peculiarity of big cities is their geographical hetero¬ geneity manifested in microclimate. Thus, during all seasons, temperature in the Balchug district of Moscow is higher by nearly 1 °C. Under all other con¬ ditions being the same, the microclimate in Moscow affects the number and diversity of some groups of microoiganisms. Thus, the taxonomic composi¬ tion of actinomycetes in soils of playgrounds approached that of more south¬ ern soils. Waterlogging and gleying, widespread in city soils, provide preservation of natural niches of some microoiganisms, in particular Azotobacter, since this microorganism spreads along rivers. In the flood plain of a river located within the area of Moscow, Azotobacter was discovered with a probability of 100%, despite the strong pollution of the river and its flood plain: 4 MACs (maximum allowable concentrations) for copper and 20 MACs, for manga¬ nese (About the Status..., 1993). Apparently, if a microorganism corresponds to its natural ecological niche, then it would be relatively low-sensitive to ur- banogenic impacts. In nature, Azotobacter that lives in gley horizons can form associations with a facultative anaerobic spore-forming bacterium Вас. sphaericus. In this respect, it should be noted that the shrinkage of the hydrographic network (that typically accompanies urbanogenesis) could destroy the natural habitats of the microorganisms yet preserved in the city. Thus, the microbial community of urbanozems acquires some features of that found in more southern soils than the soddy-podzolic ones. However, the combination of natural and human-made microzones, as it is typical for urban microbial habitats, promotes stabilization of microoiganisms at a new, though quite sufficient level. The functioning of microbial communities can be revealed using the method of "‘microbial paysages!—microbial microscopic pictures on soil par¬ ticles (Aristovskaya, 1965). In this case, the functioning of microbes is esti¬ mated by the interactions between the members of the microbial community (bacteria, fungi, and actinomycetes) on the surface of soil particles (Skvortsova et al.. 1988; Bianciotto et al., 1996). In urban phytocenoses of a
new residential area of Moscow, Mitino, the microbial community functioned only in some habitats: relatively undisturbed areas of a forest-park, abandoned construction site, and wasteland. At the same time, when the mi¬ crobial community in soils of other plots was characterized by viable bacte¬ ria, fungi, and actinomycetes, they did not interact with each other. Therefore, this can be interpreted as one of the first signs of disturbance of the microbial complex as a functioning unit of ecosystems (industrial areas, fill near heat and power station, space between yards with high recreational impact, and construction site). The method of microbial paysages can be used for moni¬ toring the effect of urbanization on soils in developing areas. People can maintain natural microbial complexes and clean the urban environment. Thus, for example, placement of soil columns with undisturbed structure, hence, with structured microbial niches, on lawns between tracks promotes the survival and functioning of microbial communities. As shown {Filip, 1978), humic acids may stimulate self-cleaning of soils from patho¬ genic bacteria. Maintenance of self-cleaning capacity of urban soils and their remedia¬ tion are necessary because they contain quite different urbanogenic products, for example, mutagenic compounds (Skvortsova et al., 1989, Dubinina and Dubinin, 1996). Municipal wastes accumulated in soil make it toxic, so pri¬ marily adversely affecting the viability' of plants (phytotoxicity) and microor¬ ganisms. Soil toxicity' is successfully monitored by both traditional methods of microbial and plant tests and by new methods considering soil properties. Thus, a method for the assesment of phytotoxicity' was proposed by Evdoki¬ mova (1995). It permits evaluation of the degree of soil pollution by heavy' metals and the uptake of the latter by plants in the amount exceeding the maximum allowable concentrations. Ca and Mg are mainly delivered by in¬ dustrial emissions. Thus, a soil in which a (Ca+Mg)/Cu ratio is less than 10 and the (Ca+Mg)/Ni ratio is less than 5 is unsuitable for the growing of plants in the city. The soil toxicity' in Moscow was estimated according to Krasil'nikov. It is worth noting that the fluvial accumulative soil-geochemical landscapes display accumulation of excessive toxicants. Higher toxicity' is observed in the lower flood plain soils of the Moskva River and its tributaries compared to less toxic soils of its high right bank.
5.4. Conclusion It became evident now that the urban soils, as a medium where microorgan¬ isms live and the urban soil cover are very heterogenous. In Moscow, the mi¬ crobial complex becomes dominated by populations adapted to technogenic conditions. Under the complicated ecological situation in the city and changed soil properties, saprotrophic microbial communities, often modified, continue to function because of their high biological and ecological plasticity. Soil micro¬ oiganisms successfully occupy new ecological niches. However, the resilience of new urban microbial communities apparently depends on the extent to which natural ecological niches and interactions were preserved in urban soils or in peat-compost matter and other mixtures placed on lawns and squares. The higher is the proportion of natural loci, the more advanced is the conser¬ vation and restoration of the natural structure of microbial communities. Pre¬ sumably, conserving ecological niches, we can promote the survival and maintain functioning of microoiganisms, so making them low-sensitive to technogenic pollution. Development of saprotrophic microorganisms in different ecological niches throughout the city causes oppressing or decline of pathogenic micro¬ organisms that accumulate in urban soils and substrates. Simultaneously, humic acids also promote the decline of pathogenic bacteria. Taking their properties into consideration, humus compounds can be recommended for remediation of urban soils. A pool of microorganisms in the lower part of the profile of urbanozems near historical monuments in the center of Moscow (the Rozhdestvenskiy and Zachat'evskiy cloisters, old villas) attested that, in the past, ecological condi¬ tions in the downtown were more favorable. Studies of soils in such areas al¬ lowed us to obtain information about the population and composition of mi¬ crobial communities that had inhabited soil horizons several centuries ago. It can be used as a reference relatively to the microbial communities of the modem city and is applicable for purposes of microbiological remediation of urban soils.
CONCLUSION Various artificial ecosystems that develop during urbanization are char¬ acterized by disturbed natural links between their constituents. All urban lands should be considered as a unified system that results from interaction of all natural and human-made media (water, grounds, vegetation, parent rocks, air, and humans). In this system, as it appears to us, soil is the basic component, since it provides the productivity of ecosys¬ tems, its functioning, resilience, and biodiversity. In Moscow, one of the largest megalopolises in the world, only 6% of the area (forests and forest-parks) is covered with quasi-natural ecosystems. The other lands are occupied by natural-urban and urban ecosystems com¬ posed of fragments of natural ecosystems surrounded by houses, industrial areas, roads, etc. Urban ecosystems include new types of human-made eco¬ systems developed as a result of degradation, destruction, and (or) substitu¬ tion of natural systems. These ecosystems hardly suit for recreation and are characterized by a breached biological cycling, by low biodiversity' mani¬ fested in their structure, composition, and functional characteristics, and by the increased number of pathogenic microoiganisms. For the maintenance and conservation of the ecological framework of the city, it is necessary' to preserve the natural diversity of all its components — including the soil — that make up the genetic fund for all adjoining areas. It is also desirable to extend laige natural systems by linking them through small strips. Only in this way, it will be possible to preserve the biodiversity and
ability of the ecosystem to self-cleaning and self-regeneration. Now in all cit¬ ies, including Moscow, links between parcels of vegetated lands are breached, while their area is shrinking and alienated. It is quite important to understand that we manage to preserve the natu¬ ral biodiversity in cities and make it sustainable only if we conserve natural ecosystems located within cities. In urban soils, the human impact dominates over natural factors of soil formation. As a result, peculiar types of soils and soil-like bodies develop un¬ der new environmental conditions. In order to conserve nature in the city, it is very important to maintain its soil cover in such a state that the soils can most optimally perform their eco¬ logical functions. Therefore, all functioning urban soils play a great role for ecology and the sanitary' status of cities. Instead of natural ecosystems de¬ stroyed in most of the urban areas, urbanization creates “roofs-and-asphalt” landscapes intermingled with open “unsealed” sites. Towns and industrial centers can be understood as specific urban ecosystems, where soils are the most important component. Unfortunately, this role of soils is poorly studied and mostly ignored nowadays. The role of urban soils is essential and diverse. They provide condi¬ tions for the growth of vegetation, absorb pollutants, and prevent pene¬ tration of the latter to soil and ground waters, and dust emission into the urban air. The soil changes the chemical and gaseous composition of the atmos¬ pheric precipitation and groundwater. It appears to be the universal biological adsorbent, source, and regulator of the content of C02, 02, and N2 in the air and controls the dynamics of temperature and moisture in surface layers of the atmosphere. Owing to its properties and huge active surface, soil is the sink for toxic compounds and one of the most important biogeochemical barriers for many compounds (heavy metals, mineral fertilizers, pesticides, oil products, and so on) as they migrate from the atmosphere to groundwater and rivers. At the same time, because of the low proportion of open surface in cities and indus¬ trial centers, the majority of precipitation escapes soil to discharge directly through canalization into rivers. Morphogenetic and physicochemical properties of urban soils signifi¬
cantly differ from soils of rural areas. They are characterized by the disturbed arrangement of soil horizons, the absence of the protective layer of forest lit¬ ter, accumulation of construction and household waste and technogenic pol¬ lutants, specific biota, which includes pathogenic species, by a strong shift in pH towards alkalinity, high content of nutrients, increased soil compaction, etc. In addition, urban soils have specific water and temperature regimes. Si¬ multaneously, urban soils are characterized by humus formation, lessivage, leaching and redistribution of mineral components, and other pedogenic proc¬ esses typical for natural soils in the region. Despite the sufficient provision with major nutrients, some factors (high pH, functioning, compaction, and contamination with heavy metals and other toxic compounds) limit the fertil¬ ity of urban soils. For inventory and mapping of urban soils as well as for the manage¬ ment of soil processes, we pioneered their classification based on changes in the morphological profile and the type of substratum for the southern taiga subzone of Russia. We also developed methods for description of their pro¬ files and horizons. The following groups of soils in towns are recognized: natural soils, superficially transformed natural soils (urbo-soils), deeply trans¬ formed soils (urbanozems), and superficially humified human-made soils and substrates (urbotechnozems). In addition, a more thorough subdivision has been developed. Urbanozems are genetically independent soils that possess features of both natural and human-made soils. Urban soils can develop on filled grounds and cultural layers and through the transformation of natural soils. In addition, criteria were elaborated to recognize soils by the degree of disturbance, manner of formation, thickness, and abundance of inclusions. In big cities, the soil surface is often sealed with solid cover This causes decapitation of the soil profile, while soil itself is buried and degraded. It is proposed to recognize a separate group of soils, ekranozems, sealed with as¬ phalt, concrete, and other impermeable layers. There are useful recommenda¬ tions how to rehabilitate ekranozems and how to use them afterwards. Of course, it is impossible to fully avoid soil sealing with asphalt, roads, pavements, and so on, since it is necessary for human activities in the city and saves the population from dust and mud. Presently, there are no standards about the ratio between sealed and open areas. However, it is obvious that it
differs by categories of urban lands. Thus, the area of open land should be typically maximized on vegetated areas, while it should be minimized on the most polluted industrial areas. Soils affected by urbanization more poorly perform some ecological functions compared to soils of natural ecosystems. Nearly 85% of the area of Moscow (residential areas, municipal dis¬ tricts, industrial and transport areas, road networks, and so on) are subject to the impact of adverse processes, which influence the ecological status of soils. As predicted by ecologists, this impact will grow. Thus, the vegetated area will shrink, while the increasing degree of soil seeding with houses, stone, as¬ phalt, etc. will decrease the surface of the biologically productive and biogeo- chemically active soil cover. In addition, hydrological conditions in soils will deteriorate (waterlogging, bogging, subsidences, and karst phenomena). The pollution of the near-surface layer of air and of the urban environment as a whole will increase. Standards on recreational use (allowable visiting rates) will be exceeded. Research of urban soils attests that for cleaning of the city and for pro¬ vision of better conditions for human life, it is necessary' to differentiate urban landscapes for localization and redistribution of the human impact, increase in the vegetated area, and improvement in the quality of urban lands. Nowadays, we do not have the ecological standard of urban land quality that establishes the maximum allowable impact on the urban envi¬ ronment to maintain ecological conditions favorable for the population and provide preservation of plant and animal species. In addition, these standards should promote sustainable use and renovation of natural resources; devel¬ opment of databases for ecological, technical, and economical parameters; monitoring of the urban environment; prediction of adverse processes and human-induced degradation of urban lands, etc. Special attention should be paid to biological properties of soils and their relation to pollution and to chemical and physical soil properties changed by adverse ecological processes. For example, the structure of microbial communities in urban soils is strongly changed. In urban areas, this is ex¬ pressed by redistribution of the biological activity of soils within the soil pro¬ file. domination of Protozoa (terribionts) in soils of recreation sites, domina¬ tion of testacides, and oppression of yellow-green algae, w'hile the last widely
occur in virgin soils. Urban soils are diagnosed by the content of ninhidrin- positive compounds, activity of cellulase and protease, soil respiration, and abundance of algae and soil animals. Soil animals and microoiganisms play the essential role in the ecology of urban soils. Burrowing activity of animals is very important for mainte¬ nance of the soil biological activity and development of plant roots. Soil fauna plays the key role in urban ecosystems, since it determines their resistance to adverse factors. City dumps and damped sites are the sources of expansion of pathogenic microoiganisms to adjoining areas. Soil invertebrates may de¬ crease the occurrence of some diseases by decreasing and regulating the number of pathogenic bacteria and microscopic fungi. Animals that burrow passages in soil promote creation and preservation of the soil structure de¬ stroyed during the city development. Microbiological and sanitary-epidemiological properties of urban soils are of great importance. The urban environment modifies the composition, number, and resistance of soil microbial communities relatively to those of undisturbed areas. High diversity of the urban soil cover and its discontinuity are reasons why certain genera and species of bacteria preserved in soil. They can survive even under conditions of local pollution and deterioration of air and water-physical properties of soils. Some bacteria may indicate urbaniza¬ tion. Thus, Azotobacter is discovered in soils of Moscow, while it is absent in soils of its vicinity. Its distribution is irregular both in space and along the soil profile. Special attention should be paid to the interrelationships between human health, microbiological properties of soils, and the sustainable status of mi¬ crobial communities that is typical for natural habitats. Pathogenic bacteria of the group Enterococcus and Escherichia coli are the source of infection in the city, while saprotrophic inhabitants of urban soils—actinomycetes and microscopic fungi—produce various toxic compounds, which cause alleigic reactions of humans.The properties of urbanozems and conditions of their formation are controlled by features of the urban environment and the living activities of people. These peculiarities of urban pedogenesis give rise to a new direction in soil science—urban soil science that deals with genesis, properties, functions, and ecology' of urbanozems and recognizes specific regularities in spatial arrangement of the soil cover in urban areas
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