Fractional and group composition of zinc and lead compounds as an indicator of the environmental status of soils

An ordinary chernozem artificially contaminated with Zn and Pb salts and reclaimed by the addition of chalk and glauconite under pot experimental conditions has been analyzed. The fractional and group composition of the metal compounds in the soil extracts have been determined according to an original combined fractionation procedure. Coefficients characterizing the changes in the environmental status of the metals under the reclamation conditions have been proposed for describing the formation tendencies of the metal composition in the soils. These are the mobility coefficients (MCs) of the heavy metals (HMs) in the soils and the stability coefficients (SCs) of the soils for the HMs. They are calculated from the analysis of the fractional and group composition of the metal compounds. The MC characterizes the environmental vulnerability of soils to the impact of HMs; the SC characterizes the environmental sustainability of soils concerning the contamination with HMs. The obtained experimental data characterize the behavior features of Zn and Pb in the studied soils. An increase in the environmental hazard has been revealed at the contamination of soils with HMs, as well as its decrease at the application of the tested ameliorants. The participation of both strongly and loosely fixed HM fractions in the development of the HM mobility in the soils and the sustainability of the soils to their impact has been shown.     

Fractional composition of nickel,copper, zinc,and lead compounds in soils polluted by oxides and soluble metal salts

The transformation of technogenic compounds of nickel, copper, zinc, and lead entering the soil as nitrates and oxides has been studied in a model experiment. It has been shown that the results of the determination of the fractional composition of the heavy metals strongly depend on the fractionating method used. The fractional composition of heavy metals that entered the soil as the readily soluble compounds mainly depends on the affinity of ions with the reaction centers of the soil components. When soils are polluted by such weakly soluble compounds of heavy metals as oxides, their transformation and, consequently, the fractional composition formed are determined, in the first place, by the solubility of these compounds and only afterwards by the interaction of the products of the dissolution with the soil. The transformation of the technogenictechnogenic zinc and lead oxides in the soils is more complete than that of copper and nickel oxides. This leads to a strong increase in the portion of the residual fraction of these elements under fractionating. The 1 N nitric acid almost does not extract copper and nickel oxides from the soil. This can be a reason for the erroneous estimation of the extent of soil pollution.     

Isotopic composition of lead in soils and street dust in the Southeastern administrative district of Moscow

The content and isotope ratios of lead were studied in soils, street dust, and snow sampled in the Southeastern administrative district of Moscow. The relationships between the lead isotope ratios and the content of different lead compounds in soils were revealed. It was shown that isotope ratios for the total lead have low information values upon low levels of lead contamination. The contribution of technogenic lead compounds to the isotopic composition of lead increases in the following sequence: total lead < acid-soluble lead < mobile lead. The effect of emissions from thermal power stations and vehicles’ exhaust on the isotopic composition of lead in the street dust and soils was estimated.     

Carbon balance in the soils of abandoned lands in Moscow region

A quantitative assessment of the carbon balance was performed in gray forest soils of the former agricultural lands abandoned in different time periods in the southern part of Moscow oblast. It was based on the field measurements of the total and heterotrophic soil respiration and the productivity of biocenoses. Geobotanical investigations demonstrated that the transformation of the species composition of herbs from weeds to predominantly meadow plants occurred in five–ten years after the soil was no more used for farming. The amount of carbon assimilated in the NPP changed from 97 g C/m² year in the recently abandoned field to 1103 g C/m² year in the 10-year-old fallow, and the total annual loss of carbon from the soil in the form of CO₂ varied from 347 to 845 g C/m² year. In five years, the former arable lands were transformed into meadow ecosystems that functioned as a stable sink of carbon in the phytomass and the soil organic matter.     

Dynamics of contamination of urban soils with lead in the eastern district of Moscow

Spatial-temporal trends were revealed in the contamination of Moscow soils with lead as a priority pollutant emitted with automobile exhaust. From the data of 1989 and 2005, maps of technogenic lead aureoles in soils of the eastern district were compiled, the average annual rate of increase in the element content was estimated, and its doubling time was predicted. Ecological-indication properties controlling the accumulation of lead in soils were determined.     

Fractional composition of redox systems in the soils of coal mine dumps

Specific features of the development of redox systems in the soils of coal mine dumps in Kemerovo oblast were studied. The quantitative characteristics of the fractional composition of the oxidized and reduced components in these soils were obtained, and their heterogeneity was shown. Distribution patterns of the reduced and oxidized components in the parent material of these specific technogenic landscapes in the course of soil evolution were revealed.     

Concentrations and composition of polycyclic aromatic hydrocarbons in the granulodensimetric fractions of soils in Moscow parks

A comprehensive study of the contents and composition of 15 compounds from the group of polycyclic aromatic hydrocarbons in granulodensimetric fractions of soddy-podzolic soils was performed. The specificity of the accumulation of these substances in the clay (heavy-weight) and light-weight soil fractions was investigated. The levels of the soil contamination in Moscow parks with polyarenes were determined, and the assessment of changes in the degree of the soil contamination over a long period of time was made.     

Self-purification of loamy-sandy agrosoddy-podzolic soils polluted by sewage sludge in the eastern Moscow region

For 12 years, the contents of Zn and Cd compounds in the plow horizons of the loamy-sandy agrosoddy-podzolic soils polluted due to the application of sewage sludge decreased by 2 times; the Cu and Ni concentrations became lower by 1.5 times. The thickness of the polluted layer increased from 20 to 45 cm. The reserves of Cd, Zn, and Cu in the 0- to 50-cm-thick layer decreased, on the average, by 22, 14, and 9%, respectively. The changes in the fractional composition of the metal compounds were found. The sum of the Cu and Ni compounds increased due to the fraction of these metals bound with organic matter; for the Cd compounds, due to the weakly adsorbed fraction.     

Ecological status of soils in Moscow Zoo

The quantitative assessment of the status of soils in Moscow Zoo was performed using traditional and original methods based on the differentiated system of indices. The studies were conducted in animal open-air cages and on plots available for visitors. The dynamics of the temperature and water-air regimes in the root-inhabited layer, the density, the acidity, and the salinity of the soils were studied. The level of the biological activity was assessed according to the intensity of the organic matter decomposition and the substrate-induced respiration. In the background of the rather satisfactory status of the soils, negative factors were found: a periodic excess or deficit of moisture and, for the most part, low biological activity (low respiration and decomposition of the lignin-cellulose test material). Recommendations for the improvement of the status of the soil cover in Moscow Zoo are proposed.     

Polycyclic aromatic hydrocarbons in soils of Moscow

The contents of polycyclic aromatic hydrocarbons (PAHs) in the upper horizons of Moscow soils range up to 1400 mg/kg for individual compounds and up to 10000 mg/kg for their sum. The concentration coefficients of PAHs in the soil vary from 0.7 to 200 depending on individual polyarene properties and land use. The heavy polynuclear structures of technogenic origin have the highest concentration coefficients. The highest accumulation of PAHs is observed for the soils of dumping sites, residential-transport areas, and industrial zones. According to the state sanitary norms set in the Russian Federation for the content of benzo[a]pyrene in soils, more than one-third of the urban soils studied are classified as pure, and about half soils are classified as acceptable.     

Specific features of the ecological functioning of urban soils in Moscow and Moscow oblast

Urban soils (constructozems) were studied in Moscow and several cities (Dubna, Pushchino, and Serebryanye Prudy) of Moscow oblast. The soil sampling from the upper 10-cm-thick layer was performed in the industrial, residential, and recreational functional zones of these cities. The biological (the carbon of the microbial biomass carbon, C_mic and the microbial (basal) respiration, BR) and chemical (pH_water and the contents of C_org, heavy metals, and NPK) indices were determined in the samples. The ratios of BR to C_mic (the microbial respiration quotient, qCO₂) and of C_mic to C_org were calculated. The C_mic varied from 120 to 738 μg C/g soil; the BR, from 0.39 to 1.94 μg CO₂-C/g soil per hour; the C_org, from 2.52 to 5.67%; the qCO₂, from 1.24 to 5.28 μg CO₂-C/mg C_mic/g soil per h; and the C_mic/C_org, from 0.40 to 1.55%. Reliable positive correlations were found between the C_mic and BR, the C_mic and C_mic/C_org, and the C_mic and C_org values (r = 0.75, 0.95, and 0.61, respectively), as well as between the BR and C_mic/C_org values (r = 0.68). The correlation between the C_mic/C_org and qCO₂ values was negative (r = −0.70). The values of C_mic, BR, C_org, and C_mic/C_org were found to correlate with the ammonium nitrogen content. No correlative relationships were revealed between the determined indices and the climatic characteristics. The principal component analysis described 86% of the variances for all the experimental data and clearly subdivided the locations of the studied soil objects. The ANOVA showed that the variances of C_mic, C_org, and BR are controlled by the site location factor by 66, 63, and 35%, respectively. The specificity of the functioning of the anthropogenic soils as compared with their natural analogues was clearly demonstrated. As shown in this study, measurable biological indices might be applied to characterize the ecological, environmental-regulating, and productive functions of soils, including urban soils.     

Fractional composition of humus in leached chernozems and gleyed podzolized chernozem-like soils of the northern forest-steppe zone

The composition of humus in leached chernozems differs from that in gleyed podzolized chernozem-like soils in the northern forest-steppe zone of European Russia. Leached chernozems have the fulvate-humate humus. Gleyed podzolized chernozem-like soils have the humate-fulvate humus. A more aggressive composition of humus in the latter soils is caused by their overwetting and the development of gley processes under conditions of a stagnant-percolative soil water regime.     

Concentration and distribution of polychlorinated biphenyls in soils of Moscow

The concentration of polychlorinated biphenyls (PCB) in the soils of Moscow has been determined by gas chromatography and high-resolution mass spectrometry (GC-HRMS). The total concentrations of 19 indicator and dioxin-like congeners, as well as PCBs in surface soils, are 2.85–60.62 μg/kg (the most contaminated sample was 4591.99 μg/kg). The average value, excluding the most contaminated sample, is 14.44 μg/kg, which is characteristic of residential areas of industrialized countries. This indicator varies insubstantially depending on the functional zone of the city. The toxicity equivalent of 12 dioxin-like PCBs in soils is 1.92 ng I-TEQ/kg on average and varies in a range from 0.15 to 334.12 ng I-TEQ/kg. The fraction of PCBs in the total toxicity of dioxins and dioxin-like compounds in soil varieties is 16.7–85.4%.     

Fractional and group composition of the Mn, Cr, Ni, and Cd compounds in the soils of technogenic landscapes in the impact zone of the Novocherkassk Power Station

The compounds of Cr, Ni, Mn, and Cd in the soils around the Novocherkassk Power Station and the influence of the technogenic and natural factors on their composition were investigated. The data on the fractional and the group composition of these compounds proved to be informative for assessing the ecological state of the soils. The soil components specifying the accumulation and the properties of the heavy metal compounds in the polluted and unpolluted areas were identified.     

Changes in physical properties and carbon stocks of gray forest soils in the southern part of Moscow region during postagrogenic evolution

Changes in carbon stocks and physical properties of gray forest soils during their postagrogenic evolution have been studied in the succession chronosequence comprising an arable, lands abandoned 6, 15, and 30 years ago; and a secondary deciduous forest (Experimental Field Station of the Institute of Physicochemical and Biological Problems of Soil Science, Russian Academy of Sciences, Pushchino, Moscow region). It is found that carbon stocks in the upper 60-cm soil layer gain with increasing period of abandonment, from 6.17 kg C/m² on the arable land to 8.81 kg C/m² in the forest soil, which represents the final stage of postagrogenic succession. The most intensive carbon accumulation occurs in the upper layer of the former plow (0- to 10-cm) horizon. It is shown that the self-restoration of gray forest soils is accompanied by a reliable decrease of bulk density in the upper 10-cm layer from 1.31 ± 0.01 g/cm³ on the arable to 0.97 ± 0.02 g/cm³ in the forest. In the former plow horizon of the arable–abandoned land–forest succession series, the portion of macroaggregates increases from 73.6 to 88.5%; the mean weighted diameter of aggregates, by 1.6 times; and the coefficient of aggregation, by 3.8 times. Thus, the removal of lands from agricultural use results in a gradual restoration of their natural structure, improvement of soil agronomical properties, and carbon sequestration in the upper part of the soil profile.     

Water budget items and temperature regime of postagrogenic soddy-podzolic soils of Moscow region and their effect on the soil properties

The postagrogenic transformation of the plow horizon of soddy-podzolic soils under a mown meadow and an artificially planted dense spruce stand has been studied in relation to the microclimatic specificity, water budgets, and soil temperature regimes in the compared cenoses. Over 20 years, a considerable part of precipitation reaching the soil surface under the meadow cenosis has been discharged with the surface runoff and subsurface lateral water flows. The soil warming in summer has been considerable, and the soil freezing in winter has been relatively weak. As a result, a gray humus horizon with well-shaped fine granular and coprolitic structure has been formed within the body of the former plow layer. Under the spruce stand, a larger part of atmospheric moisture has been infiltrated into the soil. The microclimatic conditions under the spruce stand have been more humid and colder. As a result, a thinner humus horizon with a considerable admixture of weakly decomposed plant debris has been formed in the upper part of the former plow layer. Below, a newly formed horizon with a specific thin platy (schlieren) structure ha been developed. The morphology of this horizon resembles the morphology of the eluvial horizon in virgin soddy-podzolic soils.     

Iron compounds in sulfate-carbonate soils on red-colored Cambrian rocks in the southern Angara region

In some regions of Irkutsk oblast in the southern Angara region, brown carbonate-sulfate soils have been formed on red-colored Cambrian rocks. In the automorphic soils, even a low content of hematite strongly affects the soil color, and the increase in its content only slightly enhances the red color of the soil. The brown color of carbonate soil is due to the partial preservation of lithogenic hematite in the upper part of the soil profile. The abundant gypsum “preserves” the lithogenic hematite in the carbonate-sulfate soil; the oxidation of iron is also hampered in this soil. Important changes occur in the wetted dark solonchak: lithogenic hematite is dissolved, the structure of iron chlorite loses order, and coarse and crystallized magnetite is formed in the humus horizon.     

The nature and composition of amorphous material and free oxides in some temperate region and tropical soils

Abstract

Amorphous clay separated from pedons of a highly weathered soil previously classified as Oxisol and an Ultisol of the Southern States and, from the surface horizons of an Oxisol and two Andepts of the tropics were studied by chemical, DTA, infrared and X‐ray analysis.

Considerable amounts of amorphous material, 20–37% in temperate region and 29–40% in tropical soils, were extracted by differential dissolution using 0.5 N NaOH. The molar SiO₂/Al₂O₃ ratios of the dissolved material varied from sesquioxidic to siliceous (0.36–9.1) in temperate region soils, whereas those of the Andepts were allophonic (1.5–1.7). DTA and infrared analysis confirmed these results, however the strong gibbsite peaks in the X‐ray analysis of temperate region soils suggested that the aluminum fraction dissolved was in part, if not all, crystalline in nature. Indications were obtained with DTA and infrared that Na‐dithionite treatment might have altered the nature of the clay.     

Ecological status of soils and tree plantations of residential landscapes in Moscow

The status of tree vegetation in urban residential landscapes is worse than in natural forest ecosystems. The properties of the topsoil horizons undergo various transformations and the soil quality drops. The range of changes depends on the period of the settlement and the type of the use of the area. The most favorable conditions for plant development and the best ecological status of soils are seen in the regions with the shortest period of human habitation and low direct anthropogenic impact. Considerable degradation of chemical, biological, and physical soil properties in combination with high anthropogenic impact exerts an unfavorable effect on the status of soils and vegetation.