Ecological-geochemical assessment of hydrocarbons in soils of Northeastern European Russia

The background contents of hydrocarbons (HCs) in soils of the far-northern and northern taiga of the Komi Republic were assessed. It was found that the soils of accumulative landscapes are enriched with HCs in comparison with the soils of eluvial landscapes. The differentiation of the HCs among the soil genetic horizons is more pronounced in the soils developed on loamy parent rocks (gley-podzolic and bog-podzolic soils) and less pronounced in the soils developed on sands (podzols and humus-illuvial bog-podzolic soils). The organic, litter, and illuvial horizons serve as a geochemical barrier in the pathway of the HC migration within the soil profile. A database for the mass fractions of HCs in the soils was created using GIS technologies, and a sketch map of the HC distribution in the soils was developed on its basis. The results obtained for the back-ground content of HCs are used for assessing the contamination of soils with oil and oil products and for gaining ecological expertise in the development of regional deposits of natural resources (raw hydrocarbons).     

Water-soluble low-molecular-weight organic acids in automorphic loamy soils of the tundra and taiga zones

The formation features of water-soluble low-molecular-weight organic acids (LMWOAs) in a zonal series of automorphic soils on loose silicate rocks from the middle taiga to the southern tundra (typical podzolic, gley-podzolic, and surface-gley tundra soils) were first revealed by gas chromatography mass spectrometry and gas-liquid chromatography. The content of LMWOAs varies within the range of 1–14 mg/dm³, which corresponds to 1–5% of the total carbon of the water-soluble soil organic matter. It has been shown that a subzonal feature of gley-podzolic soils in the northern taiga is the high content of LMWOAs, including primarily the strongest aliphatic hydroxyl acids. Possible mechanisms of their formation and accumulation in soils have been considered.     

Hydrocarbon status of soils in the asphalt deposit area (Samara Bend)

The composition and distribution features of the main components of soil hydrocarbon complex― organic (noncarbonate) carbon, hexane bitumoids, and individual polycyclic aromatic hydrocarbons (PAHs)―in the area of depleted Bakhilovo asphalt deposit (Samara oblast) have been studied. According to their proportions, three genetic types of soil hydrocarbon status are distinguished: (a) emanation–injection type prevailing within the limits of the former production field and characterized by anomalous contents of heavy resinous bitumoids (5000–7000 mg/kg on the average) throughout the soil profile and a high content of PAHs (4–9 mg/kg on the average, 29 mg/kg as the maximum, with the dominance of naphthalene homologues); (b) emanation–biogeochemical type confined to mechanogenically undisturbed soils within and beyond the deposit area, where the emanation component is manifested in soils with heavy texture and higher concentrations and very light composition of bitumoids in the lower parts of the soil profile; and (c) atmosedimentation–biogeochemical type characteristic of conventionally background soils with light texture; benzo[a]pyrene traces are detected among PAHs in the upper soil horizon, which indicates the input of this hydrocarbon with aerosols from the atmosphere; the concentrations of bitumoids and PAHs in parent rocks are lower than in the soils.     

Bioaccumulation of polycyclic aromatic hydrocarbons in the soil-plant systems of the northern-taiga biocenoses

Regularities in the formation of the pool of priority polycyclic aromatic hydrocarbons (PAHs) in the soil-plant systems of the northern taiga forest biocenoses were revealed. In soils and plants, PAHs mainly consisted of 3- and 4-nuclear structures. The content of polyarenes in plants on technogenically contaminated areas exceeded the background values by 2–5 times. The maximum bioconsumption of polyarenes was observed for bilberry leaves and Siberian spruce sprouts 4–5 years old. The highest mass fraction of PAHs was found in Siberian spruce plants of a mixed spruce-birch forest of the northern taiga. It was revealed that bilberry plants are hyperaccumulators of light PAHs.     

The role of soils in the regional carbon budget of pine forests in Karelia

The carbon pool and its fluxes were studied in Karelian pine forests of automorphic sites for the characterization of the regional carbon cycle. On the permanent sample plots arranged in pine stands (dominant forest types) of the middle and northern taiga, the structure and dynamics of the phytomass, as well as the composition of the soil organic matter, were investigated. The contribution of different components of the forest ecosystems to the regional carbon budget was studied. The carbon pools in the soils of the middle and northern taiga subzones were 330–440 × 10² and 440–550 × 10² kg/ha, respectively. The share of soil carbon in the total carbon pool of the forest biogeocenoses studied amounted to 46–35 and 33–24%, respectively. The period of considerable carbon fixation in the pine ecosystem (nearly 20 × 10² kg/ha/yr) turned out to be limited to the middle-aged stands. In the mature and overmature pine forests, only 4 × 10² kg of C/ha/yr were fixed. The main part of carbon in the soil (65–75%) was contained in the illuvial horizons, although its content there was less that 1% as compared to 30–50% in the forest litters. On industrial harvesting of wood, the main reserves of soil carbon are not spent; only the fund of mobile carbon in organic horizons of poor soils is exhausted or carbon accumulates intensely due to the development of continuous plant cover on fertile soils.     

Polycyclic aromatic hydrocarbons in soils and lower-layer plants of the southern shrub tundra under technogenic conditions

In soils and plants of the southern shrub tundra, 15 polycyclic aromatic hydrocarbons (PAHs) have been detected by high-performance liquid chromatography. Polyarenes in emissions, soil organic horizons, and plants mainly include low-molecular-weight PAHs: naphthalene, fluorine, and pyrene. The contents of the total PAHs in soils and plants exceed the background levels by 3–5 times. The distribution of polyarenes among the organs of the studied plants is nonuniform and depends on the plant species and technogenic load on the area. The studied plants include both hyperaccumulators of polyarenes (Pleurozium schreberi) and indicators of PAHs in the soil (Polytrichum commune). Pleurozium schreberi is the most abundant species in the areas under study, and it accumulates the largest mass fraction of PAHs. The differences in the accumulation of PAHs by the plants of the tundra and taiga zones have been revealed.     

Availability of elements in tundra soils on acidic and ultramafic rocks in the Polar Urals

The chemical properties of soils and their particle-size distribution in ecotopes of the Polar Urals mountain tundra were considered in relation with the lithological and geochemical features of the parent rocks. In the soils of ecotopes on the ultramafic massif, the contents of the total Ni (2830 mg/kg) and the total Cr (2327 mg/kg) were found to exceed their clarke values, which suggested the accumulation of these elements by plants and their migration with water. In the soils of the ultramafic massif, the average content of mobile Ni was 46.8 mg/kg, which exceeded the Ni MPC by 11.7 times. The average concentration of mobile Cr in the soils of the massif made up 0.35 MPC. In the soils of geochemical acidic rocks, the contents of mobile Ni and Cr were lower than their MPC levels. A higher content of particles with an average diameter ≥5 μm was found in the soils of the ultramafic massif.     

Soils with complex organic profiles on the Vasyugan Plain

Soils with intricate patterns of their humus profiles developing in the neutral-calcium landscapes of the southern taiga of Western Siberia under highly dynamic paleogeographic, climatic, and weather conditions are characterized. The specific features of these soils comprise the diverse modern humus horizons along with the relic ones of different preservation rates, shallow leaching of carbonates, and a weak development of the middle-profile soil horizons. Specifying these organo-accumulative soils is substantiated by their high humus content against the geochemical background of the clayey calcareous parent rocks. The conjugated series of soils reflect different stages of the soil evolution (the humus profile degradation, the development of eluvial process, and the increase of contrasts in the acid-base conditions) and the hydromorphic transformation accompanied by the formation of organic horizons making the humus profile more complicated. In accordance with the diagnostic horizons, the position of the soils studied was determined in the Classification and Diagnostics of Soils of Russia. The relic enrichment of the humus horizon is proposed to be used as a specific feature of these soils.     

Dynamics of the agrochemical fertility parameters of arable soils in the southwestern region of Central Chernozemic zone of Russia

Data of the agrochemical survey of arable soils in Belgorod oblast during the period from 1964 to 2014 have been analyzed. The soil cover mainly consists of typical chernozems (Haplic Chernozems) and leached chernozems (Luvic Chernozems) in the forest-steppe zone and ordinary chernozems (Calcic Chernozems) in the steppe zone. Under long-term agricultural use (from 1964 to 2014), the content of mobile phosphorus in arable soils of the region under study has increased from 55 to 137 mg/kg, and the content of mobile potassium has increased from 105 to 147 mg/kg. During the period of 1976–2014, the share of acid soils has increased from 22.8 to 45.8%, including medium-acid soils from 1.5 to 12.6%. No significant changes in the weighted average content of soil organic matter are revealed for the period from 1985 to 2014. The value of this parameter is within the range of 4.8–5.0%. In the 2010–2014, 95.0% of arable soils belonged to the category of low supplied with mobile sulfur; 99.2, 96.9, 94.1, and 54.4% of soils were poorly supplied with zinc, copper, cobalt, and manganese, respectively. During the same period, the maximum average productivity of the crop area (3710 f. u./ha) was noted at the application of 4.8 t/ha organic fertilizers and 97.9 kg/ha organic fertilizers on the average. The maximum long-term yields of sugar beet (36.8 t/ha) and corn grain (4.97 t/ha) were obtained at the application of relatively low fertilizer rates.     

滕州表层土壤硒异常特征及来源分析

为确定影响滕州地区表层土壤硒含量变化的因素,对研究区土壤的地球化学指标进行统计分析,结果显示,研究区土壤硒背景值为0.08mg/kg,异常下限值为0.17 mg/kg,表层土壤硒平均含量为0.23 mg/kg,标准差为0.144 mg/kg,变异系数为62.6%。综合相关性分析、主成分分析以及富集因子分析结果,表明表层土壤硒异常主要受人为因素的影响。不同区域表层土壤硒含量由高到低依次为煤矿区交通繁忙区农田区。在土壤垂直方向上,煤矿周边土壤中硒含量自下而上增加的趋势要明显快于不受煤矿直接影响的区域,同时前者的变化速率和转折端的出现均快于后者。因此,滕州地区表层土壤硒异常主要受煤矿开发的影响。     

Geographical features of the distribution and renewal of easily decomposable organic matter in virgin and arable zonal soils of European Russia

A decrease in the depth of organic surface horizons (forest litters and steppe mats), the reserves of organic matter in them, and an increase in their renewal rate were noted for virgin and fallow soils when going from the southern taiga to the dry steppe zone. Zonal changes in the content and reserve of easily decomposable soil organic matter showed a similar tendency: these parameters regularly decreased from soddy-podzolic soils of the southern taiga to chestnut and light chestnut soils of the dry steppe. An exception from this series is provided by fallow chernozems of the steppe zone noted for the lowest content and reserve of labile organic matter in the series of soils studied. Similar, although less pronounced, tendencies were observed for the arable soils.     

Polycyclic aromatic hydrocarbons in background podzolic and gleyic peat-podzolic soils

The qualitative and quantitative composition of polycyclic aromatic hydrocarbons (PAHs) has been determined in the background podzolic and gleyic peat-podzolic soils of the middle and northern taiga zones of northeastern Europe using the methods of highly efficient liquid chromatography and chromato-mass spectrometry. The distribution of polyarenes in the soil profiles follows the eluvial-illuvial pattern. Organic and illuvial horizons are the biogeochemical barriers for PAHs migrating in the soils. The revealed regularities of the accumulation and redistribution of PAHs in the soil profiles are in agreement with the character of the soil-forming processes in the northern and middle taiga zones.     

Mercury in humus horizons of soils in the Transbaikal region

The total mercury content has been determined in gray forest soils, chernozems, chestnut soils, and in different parent materials in the Transbaikal region. The mercury content is below the clarke value in the intrusive, effusive, and alluvial soil-forming rocks (0.004–0.024 mg/kg). In the humus horizons of the soils, it reaches 0.011–0.026 mg/kg, which is higher than the clarke value for the pedosphere. The mean background content of mercury in the soils of the Transbaikal region is 0.018 mg/kg. No significant positive correlation between the mercury content and the humus content of the soils has been revealed.     

An experience in regional estimates of changes in soil carbon pools of the southern taiga and forest-steppe during the historical period

Regional estimates of changes in soil organic carbon (SOC) pools during the historical period were obtained according to a unified approach for Kostroma (southern taiga) and Kursk (forest-steppe) oblasts. The potential pools of soil carbon were calculated with due account for the classification position of particular soils, their texture, and the character of natural vegetation. In the estimates of actual SOC pools, land use patterns and the age structure of forest stands were taken into account. It was shown that modern pools of organic carbon in the soils of Kostroma oblast are only 1–2% smaller than the potential pools; for the soils of Kursk oblast, this difference reaches 23–27%. Mean weighted values of the actual SOC contents in these oblasts decreased by 0.1–0.2 and 6.5–7.6 kg C/m² in comparison with the potential SOC contents, respectively, which is related to their environmental specificity and to different types of land use at present and in the historical past.     

文山植烟土壤有效锌含量及其影响因素研究

为探明文山烟区植烟土壤有效锌分布情况及其影响因素,并为烤烟合理施用锌肥提供理论依据,运用GPS定位技术采集了276份土样,测定其有效锌含量,采用经典统计学方法和GIS技术,对其基本特征、空间分布状况及影响因素进行了分析。结果表明:(1)文山烟区植烟土壤有效锌平均含量为1.93 mg/kg,变幅为0.20~8.17 mg/kg,变异系数为70.47%,属于中等变异强度。全烟区有70.12%的区域土壤有效锌在适宜范围内(1.00~5.00 mg/kg)。(2)县域间植烟土壤有效锌平均含量从高到低排序为:麻栗坡西畴县文山县马关县砚山县丘北县广南县。(3)土壤中有效锌含量随着有机质增加而增大,随海拔升高呈抛物线变化;不同海拔组和有机质组间有效锌含量差异均达极显著水平。有效锌含量在土壤p H为6.5~7.5时最低,在偏酸和偏碱的环境中含量较高。(4)文山烟区分布最广的是红壤,其次是黄壤。不同土壤类型有效锌含量差异达极显著水平,含量最高的是水稻土,最低的是紫色土。因此,文山烟区植烟土壤有效锌含量总体满足优质烟叶生产的需求,部分缺锌区域应加强锌肥、有机肥的施用以提高土壤中有效锌含量。     

柴达木农田土壤Cd的积累影响及风险预测

【目的】土壤重金属空间结构特征是土壤环境质量评价及重金属污染评价的基础。本文用地质统计学方法研究了柴达木盆地原生地和耕种50年的农田土壤镉的空间分布特征,对土壤镉进行质量评价,同时分析了农业耕种对土壤镉积累的影响,调查统计了灌溉水、肥料、农药等农业源土壤镉的输入量,为农田镉积累的风险预测提供参考。【方法】以柴达木盆地诺木洪农场的一块原生地（从未耕种过的土地,可以认为无化肥污染）和一块耕种地（已种植了50年的农田）为研究对象,从原生地采集22个土壤样本,耕种地采集50个土壤样本进行镉含量的测定,同时检测灌溉水、农药、化肥中的镉含量,并进行每年农田输入量的统计。用Excel软件进行数据处理,反比权重法（IDW,Inverse Distance Weighting）插值,GIS9.3进行空间分析和图像处理;以单项污染指数法评价土壤镉质量,评价模式为Pi=Ci/Si（Pi为污染物镉的单项污染指数,Ci为污染物镉的实测数据,Si为污染物的评价标准）。评价标准分别以农业部公布的行业标准《无公害食品 枸杞生产技术规程》（NY/T 5249-2004）和《绿色食品 枸杞》（NY/T1051-2006）产地环境标准要求下的《绿色食品 产地环境技术条件》（NY/T 391-2000）为依据。依据农业源土壤镉输入量,以土壤现状值为起点,以绿色食品标准限量值为终点,测算输入量积累突破两端差值的年限。【结果】原生地22个土壤样品的镉平均含量为0.30 mg/kg,是土壤背景值的两倍（0.14 mg/kg）,达到无公害食品（0.60 mg/kg）和绿色食品（0.40 mg/kg）标准;种植50年农田的50个土壤样品的镉平均含量为0.43 mg/kg,是土壤背景值的3倍,达到无公害食品标准,但超过绿色食品标准。用于灌溉的河水的镉含量为0.0036 ng/kg。检测生产中使用的15种农药和7种肥料,其中的镉导致每年土壤镉增加3444 mg/hm2。最严重的污染源是鸡粪,施入土壤后每年导致土壤镉增加2025 mg/hm2,其次依次为复合肥（使土壤镉增加576 mg/hm2）,磷酸二铵（增加432 mg/hm2）,有机肥（增加360 mg/hm2）。【结论】以小尺度空间分布和全量统计研究的诺木洪农场土壤镉含量这一单一指标衡量,可以看出诺木洪原生地土壤是清洁的,能够满足无公害、绿色食品的生产;但是研究选择的多年耕种田已经遭到重金属镉的污染,只能达到无公害食品标准,而达不到绿色食品标准。现行生产中的施肥措施是导致诺木洪土壤重金属镉污染的一个重要因素,其中鸡粪对镉污染的贡献最大,其次是复合肥、磷酸二铵和有机肥。如果继续现在这种耕种方式,以现有的原生地镉含量均值为0.30 mg/kg进行计算,76.3年后该土地镉含量将超过0.40 mg/kg的绿色标准上限。     

Physicochemical and Microbiological Characteristics of Tundra Soils on the Rybachii Peninsula

The Rybachii Peninsula is composed of Proterozoic sedimentary rocks and differs sharply from the rest of the Kola Peninsula in its geological structure, topographic forms, and parent rocks. It is dominated by Al–Fe-humus soils formed on moraines with an admixture of local rock fragments, including slates. Organic horizons of tundra soils in the peninsula are less acid than those on granitoids of adjacent mainland of the Kola Peninsula. The content of exchangeable calcium in the organic horizons varies from 17.4 to 68.0 cmolc/kg, and the content of water-soluble carbon reaches 400 mg/100 g amounting to 1–2% of the total soil organic matter content. The total number of bacteria in the organic horizons of tundra soils varies from 3.5 × 10⁹ to 4.8 × 10⁹ cells/g; and bacterial biomass varies from 0.14 to 0.19 mg/g. The length of fungal mycelium and its biomass in the organic horizons are significant (>1000 m/g soil). The biomass of fungal mycelium in the organic horizons exceeds the bacterial biomass by seven times in podzols (Albic Podzols) and by ten times in podbur (Entic Podzol), dry-peat soil (Folic Histosol), and low-moor peat soil (Sapric Histosol).     

Comparative Analysis of the Number and Structure of the Complexes of Microscopic Fungi in Tundra and Taiga Soils in the North of the Kola Peninsula

The number, biomass, length of fungal mycelium, and species diversity of microscopic fungi have been studied in soils of the tundra and taiga zones in the northern part of the Kola Peninsula: Al-Fe-humus podzols (Albic Podzols), podburs (Entic Podzols), dry peaty soils (Folic Histosols), low-moor peat soils (Sapric Histosols), and soils of frost bare spots (Cryosols). The number of cultivated microscopic fungi in tundra soils varied from 8 to 328 thousand CFU/g, their biomass averaged 1.81 ± 0.19 mg/g, and the length of fungal mycelium averaged 245 ± 25 m/g. The number of micromycetes in taiga soils varied from 80 to 350 thousand CFU/g, the number of fungal propagules in some years reached 600 thousand CFU/g; the fungal biomass varied from 0.23 to 6.2 mg/g, and the length of fungal mycelium varied from 32 to 3900 m/g. Overall, 36 species of fungi belonging to 16 genera, 13 families, and 8 orders were isolated from tundra soils. The species diversity of microscopic fungi in taiga soils was significantly higher: 87 species belonging to 31 genera, 21 families, and 11 orders. Fungi from the Penicillium genus predominated in both natural zones and constituted 38–50% of the total number of isolated species. The soils of tundra and taiga zones were characterized by their own complexes of micromycetes; the similarity of their species composition was about 40%. In soils of the tundra zone, Mortierella longicollis, Penicillium melinii, P. raistrickii, and P. simplicissimum predominated; dominant fungal species in soils of the taiga zone were represented by M. longicollis, P. decumbens, P. implicatum, and Umbelopsis isabellina.     

Soil contamination in the impact zone of mining enterprises in the Bashkir Transural region

The results of long-term studies of the contents of bulk forms of metals (Cu, Zn, Fe, Ni, Pb, Mn, Co, and Cd) and their mobile compounds in soils of background and human-disturbed areas within the Krasnoural’sk–Sibai–Gai copper–zinc and Baimak–Buribai mixed copper mineralization zones in the Bashkir Transural region are discussed. It is shown that soils of the region are characterized by abnormally high natural total contents of heavy metals (HMs) typomorphic for ore mineralization: Cu, Zn, and Fe for the Sibai province and Cu, Zn, and Ni for the Baimak province. In the case of a shallow depth of the ores, the concentrations of HMs in the soils are close to or higher than the tentative permissible concentration values. The concentrations of mobile HM compounds in soils of background areas and their percentage in the total HM content strongly vary from year to year in dependence on weather conditions, position in the soil catenas, species composition of vegetation, and distance from the source of technogenic contamination. The high natural variability in the content of mobile HM compounds in soils complicates the reliable determination of the regional geochemical background and necessitates annual estimation of background parameters for the purposes of the ecological monitoring of soils. The bulk content of Cu and Zn content in soils near mining enterprises exceeds the regional geochemical background values by 2–12 times and the tentative permissible concentrations of these metals by 2–4 times. Anthropogenic contamination results in a sharp rise in the content of mobile HM compounds in soils. Their highest concentrations exceed the maximum permissible concentrations by 26 times for Cu, 18 times for Zn, and 2 times for Pb. Soil contamination in the impact zone of mining enterprises is extremely dangerous or dangerous. However, because of the high temporal variability in the migration and accumulation of HMs in the soils, the recent decline in the ore mining activities, and the construction of purification facilities, no definite temporal trends in the contents of HMs in the soils have been found in the studied region for the period from 1998 to 2015.     

CO<Subscript>2</Subscript> Emission and Organic Carbon Pools in Soils of the Northern Taiga Ecosystems of Western Siberia under Different Geocryological Conditions

Statistical analysis of a vast body of data collected during five field seasons (2011–2015) was performed to characterize the biological activity of soils in the northern taiga ecosystems of Western Siberia. Automorphic forest soils, hydromorphic (oligotrophic bog) soils, and semihydromorphic (flat-topped and large peat mounds) soils were characterized. Statistically significant differences of average levels of CO₂ emission from the soils were identified at the ecosystem level. The CO₂ emission from podzols of automorphic forest ecosystems at the peak of the growing season (205 ± 30 to 410 ± 40 mg CO₂/(m² h)) was significantly higher than the emission from semihydromorphic soils of peat mounds (70 ± 20 to 116 ± 10 mg CO₂/(m² h)). The presence and depth of permafrost was a significant factor that affected ecosystem diversity and biological activity of northern taiga soils. Statistically significant differences in the total, labile, and microbial carbon pools were observed for the studied soils. Labile and microbial carbon pools in the organic layer (10 cm) of forest podzols amounted to 0.19 and 0.66 t/ha, respectively; those in the organic layer (40 cm) of peat cryozems of flat-topped peat mounds reached 1.24 and 3.20 t/ha, and those in the oligotrophic peat soils (50 cm) of large peat mounds were 2.76 and 1.35 t/ha, respectively. The portion of microbial carbon in the total carbon pool (C_micr/C_tot, %) varied significantly; according to the values of this index, the soils were arranged into the following sequence: oligotrophic peat soil < peat cryozem < podzol.