Megacities 2050: Environmental Consequences of Urbanization

Urbanization is a long-term global trend, responsible for substantial environmental changes. At the same time, urban ecosystems are vulnerable and their adaptation to the ever-changing environment is necessary to sustain essential functionality and important ecosystem services. Sustainable urban development demands the integration of innovative green technologies and nature-based solutions in urban management, which is only possible through a collaboration and participation of all stakeholders including scientists, landscape designers, civil engineers, policy makers, and all citizens.

Sustainable development requires principle changes in goals, indicators and values urban areas to well-known principles from the fundamental work “Limits to Growth” [20]. Multidisciplinary and cross-sectorial teams of experts, planners and authorities need to elaborate jointly national and inter-regional strategies to the ecological mode of urbanization to turn dynamics of megapolises growth to ecopolises. New type of urban and ecopolis strategies as the core of urban strategy tested on the example of Korolev science city in Moscow Region by ecosystem restoration, evaluation of risks and calculation of resources required for implementation ecological master plan. This task force elaborated and designed with strong participation with the city council of Korolev by a joint Russian and Italian team of students and professors [15].

Urban vegetation, particularly urban forests are a crucial component of green infrastructure in our cities. A strong interest is related to the ecosystem services provided to both people and the environment including CO₂ sequestration and air quality improvement. However few in situ experimental studies exist on these topics while most of the estimations derive from modelling exercise. Preliminary results of an innovative eddy covariance site located in the Real Bosco di Capodimonte within the urban area of Naples (Italy) are presented here.

Urbanization is a key land-use change pathway, increasing urban population and resulting in abandonment of rural areas. Urbanization alters profoundly soil properties and functions, including soil respiration [90]. Soil respiration includes heterotrophic (microbial) and autotrophic (root) components. Both are driven by biotic and abiotic factors. Soil respiration and its components in urban ecosystems remain poorly known. In the present study, the spatial and temporal variability of total soil respiration (Rs) and its components were analyzed for different ecosystems included in the Moscow megalopolis area. In particular, highly impacted areas of urban green lawns were compared to arable lands and urban forest sites. Respiration fluxes were monitored during the whole vegetation period. An average Rs was significantly higher for the most disturbed sites, compared to more natural sites. For all the sites, Rh was the dominant component of soil respiration. We report the highest heterotrophic respiration ratio to microbial C (qCO₂ = Rh/C_mic) for the lawn land use, followed by arable sites and forest sites, characterized by the lowest qCO₂. An average Ra contributed to total Rs only to a minor extent (26%) and increased in all study sites along the season. Ra absolute values and contribution to Rs were similar for different land use types.

Urbanization is an important trend in global land cover change and seriously impacts the soil resources. However, there is no clear definition for urban areas. As a result estimates of urbanization and its effects on soil resources vary widely. Urbanization can be modelled in different ways with a specific focus on environmental conditions, temporal dynamics and spatial patterns. The processes underlying urbanization require a hybrid approach that combines the different methods. Similarly, the unique conditions of the urban environment require specific surveying techniques for the soil resources. The global debate on urbanization and its environmental impacts calls for a rapid standardization of definitions and methodologies to come with proper information on rates and impacts.

In this study, the database of properties of urban soils was created to assess the influence of zonal features of natural factors of soils, situated in urban areas. The database contains more than 135 cities located in different natural zones all over the world from the Arctic tundra to equatorial tropics. A comparison based on two features: soil organic carbon (SOC) and water-extracted pH. A number of statistical indicators such as average value, minimum and maximum values, standard deviation, variation, correlation coefficients were calculated for each zone and feature.

The analysis of the results showed that the variation in carbon content values in urban soils is significantly higher in comparison with background soils. This fact can be explained by the influence of anthropogenic factor on the processes of organic matter reduction and accumulation in the soil. At the same time the average carbon content in urban soils in most cases is much higher than in natural soil and in general, there is a trend: the difference between SOC in urban and natural soils increases to the north and gradually decreases to the south. However, a comparative analysis of soil-bioclimatic zones neither in climatic nor in facial series there is no trend can be observed. This means that the characteristics of the SOC of urban soils are not zonal and the observed trend can be explained by the intensity of human impact. The comparison of the average values of pH in the urban and natural has not shown any statistically significant difference. However the comparison of maximum values of water-extracted pH for the groups showed a clear pattern in northern hemisphere: increasing of the alkalinity in the humid and semihumid areas from the one side, and acidification in the more southern arid and semi-arid areas from the other side, that may indicate the presence of zonal trend.

Soil chemical properties are essential for the functioning of soils in the polar biome. This study aimed to study the concentrations of heavy metals in urban soils of Harsaim, Aksarka, Salekhard, Harp and Labytnangi. At 12 sites 23 soil samples were collected at depths of 0–5 cm and 5–20 cm. Heavy metals were detected with X-ray fluorescent analyzer “Spectroscan-MAX”. The values obtained were compared with the Approxible Permissible Concentrations and Maximum Allowable Concentrations adopted in Russia. The study of soil samples from different settlements let to reveal the characteristic features of soil contamination of individual settlements with heavy metals to compare them with each other. The vast majority of samples are characterized by excess of Maximum Allowable Concentrations for arsenic, which should indicate a high regional background of this element. For a more adequate assessment of the levels of total soil contamination (Saet’s index) Zc during its calculation it was used not only average arithmetic values of coefficient of concentration (Kk), but also its average geometric values. Most of the soil samples are characterized by non-hazardous levels of total soil contamination. The study showed a statistically significant difference in content of heavy metals for the 0–20 cm layer of the soils for three elements (Cu, Zn, Ni).

Soils of Ufa city were previously under-investigated in terms of chemical pollution and anthropogenic impacts. This study shows the different trends of soil chemical transformation under different functional load (industrial zone, parks and natural environments). Anthropogenic transformed Umbric Luvisols and Albeluvisols were studied in terms of basic chemical properties and trace elements content. Data show that oil pollution results in an accumulation of carbon and nitrogen. However, this accumulation does not correspond to real humus accumulation, but to the accumulation of black-carbon-like fractions. Redistribution of trace elements over depth is typical for the contaminated soils. Zinc concentrations do not exceed the permissible values, but the trends of zinc migration down the soil profile are evident. Lead concentrations increase in contaminated soils, but permissible concentrations are not exceeded. Urban soil contamination leads not only to the accumulation of contaminants in the upper soil horizons, but also to the redistribution of some trace elements in the soil profile.

Urban soil is a sink for anthropogenic lead (Pb) and the latter is a persistent threat to human health, especially to children and the gardening population. In the past decade, several organizations have tested soil samples for Pb in New York City. Here we summarize the available soil Pb data for New York City and create a spatial distribution map. The highest Pb levels were present in the oldest parts of the city, and mostly industrial and high traffic areas. There is overlap between high Pb areas with areas of high population density and high poverty rates. The analyses help delineate parts of the city that are most affected, possible sources of Pb, and where to prioritize resources for mitigation and remediation.

The aim of investigation was to evaluate the effects of urbanization on the organic matter of urban soils in the South of Russia.

The type of vegetation has an impact on the amount and quality of soil humus. In soils of the forest-park area of the city, an increase of humus content in the upper 10-cm layer to the average value of 7.5 ± 0.63% has been observed, which is significantly higher than the humus content of arable chernozem surrounding the city (3.5−4%).

The humus profile acquires the features of the forest soil. Reduction of humus content is characteristic of buried and sealed soils. The structure and composition of humic acids is largely due to the type of anthropogenic impact. However, regardless of the nature and degree of changes, the transformation of HA molecules are within the defined soil type. The most significant changes are noted for HA from Calcic Chernozem of the forest park. The significant decrease in humus content in urban soils is due to a change of soil conditions. The fact that humic acids of chernozem are less benzenoid and characterized by more advanced peripheral portion of the molecule, with a higher degree of enrichment with nitrogen and sulfur. Sealing the soil under the asphalt leads to the development of HA oxidation and hydrogenation processes. The reduced participation of aromatic moieties in the molecules of HA in the horizon UR of Ekranic Technosol has been noted.

Leadisone of the most dangerous heavy metals for human. The studies of lead migration in the soil as are significantly important to forecast the transfer factors of lead in ecosystems. The paper represents data of lead concentration in dependence of the soil depth and degrees of anthropogenic impact. The research revealed influence of anthropogenic impact and species of arboreal vegetation on Pb migration in the soil profile. The results of lead concentration positively varyin the soil due to anthropogenic impact from 62.2 mg/kg to 139 mg/kg. The effect of arboreal vegetation species results in the high Pb migration down the soil profile in pine and birch sites and preferable accumulation of Pb in the upper humus horizon in the oak sites.

Industrial areas occupy about 18,800 ha; more than 19% of Moscow [7]. These areas consist of former production zones and abandoned landscapes with numerous warehouses and dumping grounds. More than 4300 hectares of the industrial areas will be revitalized in the near future. The first stages of construction have already begun, with projects such as “Tushinsky Airfield” and “ZIL”. Other projects that are planned for construction over the next three-five years include: “Altufyevskoye Shosse”, “Silikatnye Ulitsy”, “Ogorodny Proyezd”, “Magistralnye Ulitsy”, “Severyanin”, “Yuzhny Port”, and “Paveletskaya”. These reconstructions provide an opportunity for sustainable development of new housing and social infrastructure with the restoration of natural ecosystems in the city. Designing in harmony with nature generates the potential for dynamic development of a resilient city [2]. This approach would alter the expansive and strictly-industrial areas into a “green and blue” city framework with natural water features and green areas. Incorporation of this spatial structure model would enhance city development at all levels; effectively stimulating the economy of the Moscow region. To achieve sustainable urbanization, it is necessary to use innovative restorative design; incorporating modern construction technologies while creating harmony and preserving heritage, to optimize forest areas, water areas, and open spaces, ultimately benefitting recreation, community-building, residential and office clusters [15].

This study of forest soil ecology conducted in the forest experimental station of the Russian State Agrarian University of Moscow Agricultural Academy reveals the evolution of a soil profile over a 100-year period influenced by a change from pine and spruce stands to two-tier mixed plantations of birch, maple, linden and oak. The rates of formation of the humus horizon and the reduction of the thickness of the podzolic horizon was determined by this change. Native pine tree growth enhances the podzol development process resulting in the development of an admixture of deciduous tree populations. This growth of hardwoods succeeding into the pine forest turn reduces the rate of accumulation of the upper horizon by 3 times. Humus horizon under these mixed stands was found to be the thickest in the locations, hardwood dominated. Comparison of the taxonomic properties with the soil characteristics will help in developing criteria for the vegetation stability and productivity in urban and suburban areas. This study reveals that the composition of tree species and their successions influences the main soil forming processes in the profile of sod-podzolic soil. The results of the study can be used to predict the soil-forming processes and the states of the forests. The ability to assess and predict these conditions is extremely important for soil-ecological monitoring in recreational forests for ecological landscape mapping.

A rapid assessment of Environmental Quality Criteria and probability of Ecological Risk without special toxicometric experimenting is an actual problem in environmental science. The article presents a statistical prediction methodology of approximated no-effect concentrations (NOEC) and modelling of Species Sensitivity Distribution (SSD) based on the field observation data. We use values of species abundance of tested community, which were located on a set of sites of region under study with wide variation range of polluting substances concentration. Statistical processing includes the following sequence stages: (1) calculation of distances matrix in multidimensional species’ space between each pair sites; (2) nonmetric multidimensional scaling (NMDS) is applied to reduce a 2-dimensional plot matrix of sites and species projections; (3) the analyzed contamination mediafactors are interpreted as an ecological gradient in species compositions and construction of the additional ordination axes; (4) generalized additive models (GAM) are build and 3D smoothing surfaces of spatial distribution of pollutant’s concentration on ordination plot are fitted; (5) using the fitted models predicted values of PV ecological maxima and the upper boundary values of TV confidence intervals of each species for each single compounds are found; (6) obtained data are used for SSDs modelling. The methodology has been supported by results of bioindication for communities of microscopic fungi of soil samples from the former uranium mining province (Kyrgyzstan). Threshold values of six soil contamination indicators that ensure a pre-given admissible probability of environmental risk have been determined.

This study is focused on assessment of microbial community structure differences in urban soils by means of lipid analysis. Soil samples (0–20 cm deep topsoil layer) contaminated with trace metals to various extents were taken from six sites located in the rural part of the city of Kirov (Russia). The samples were measured for pH and total Pb, Ni, Cr, and Cd. To study the microbial community, microorganism markers (fatty acids) were extracted, which were then diagnosed by mass spectrometry. Nonmetric multidimensional scaling plots of soil communities showed relative dissimilarity in control and polluted soils. The total lipid content in control samples was found to be significantly higher than in polluted soil. The highest indicator value was assigned to Actinobacteria phylum, whose concentration decreased remarkably in polluted samples, and anaerobes Butyrivibrio sp. and Bifidobacterium sp. were regarded as an indicator for soils with relatively low pollution exposure. Microbial profiles were also indicative of selective enrichment with competent species (Desulfovibrio sp., Bacteroides fragilis, and Chlamydia sp.) in soil greatly contaminated with heavy metals. This study suggests that the method of lipid diagnostic can be highly indicative of soil microbial structure and thus it can be used as a quantitative measurement of urban soil biological quality.

The paper presents the regional automated system of soil functional-environmental assessment (RASSCA) reflecting soil provincial genesis and functional features. It allows evaluating soil integral functional and environmental quality even in heterogeneous land plots. The RASSCA identifies and quantifies the limiting factors and principal parameters of soils’ functional quality and environmental status as well as priority issues of their land-use. The RASSCA conducts environmental computer simulation, search and target prediction of soil quality changes and environmental problems’ solution that improve the effectiveness of land-use decision-making – by prior functional-environmental analysis and comparison of the various scenarios of their outcomes and consequences. The RASSCA was used for the functional-environmental analysis of urban soils in the Chernozemic region of Russia (Kursk city), where natural soils are dominated by Chernic Phaeozems and Luvic-Chernozems. We focused on the polluted urban soils to identify the key environmental problems of soil technogenic degradation. The RASSCA allowed evaluating soil limiting parameters and environmental factors to identify the priority issues and to model the target changes in the integrated functional-environmental quality of soils by improving their limiting parameters. Conducted monitoring of Kursk soil technogenic successions highlighted the importance of soil metamorphic and migration processes. The over-compaction in urban soils was up to 0.3 g cm⁻³ year⁻¹; an average rate of humification/dehumification– 3.0 g kg⁻¹ year⁻¹; acidification/alkalization −0.1 pH year⁻¹ and heavy metals migration – up to 50–60 g cm m⁻² year⁻¹. Some of these data considerably extend the known ranges of elementary soil processes rates “in situ” and allow for better estimation of the real potentials of soil functioning in different landscape-environmental conditions of forest-steppe zone.

In terms of the urban planning cities regeneration the post-industrial brownfield landscapes, directly adjacent to the modern residential quarters, become most vulnerable in the structure of urban planning tissue. These “space erosion holes of urban planning fabric” create centers of socially insecure and marginal urban environment formation. The aim of this work is to analyze of modern trends, identification of priority principles of landscape urbanism and its implementation into the formation process of residential structures within these areas to ensure sustainable, socially integrated and environmentally comfortable living environment.