Total Heavy Metal Concentrations Research Articles

How do properties and heavy metal levels change in soils fertilized with regulated doses of urban sewage sludge in the framework of a real agronomic treatment program?

This field study was performed to assess the variation in chemical and agronomic properties and total and extractable concentrations of heavy metals in soils fertilized with regulated doses of urban sewage sludge (USS) for 6 consecutive years in the framework of an agronomic treatment program. Chemical and agronomical properties, total contents and extractable concentrations of Cd, Cr, Cu, Hg, Ni, Pb and Zn were determined in agricultural soils treated with USS for 6 consecutive years, agricultural soils cultivated using mineral fertilizers and uncultivated soils representative of the local geochemical background. USS application caused a decrease in pH and an increase in extractable concentrations of Cr, Cu, Pb and Zn. No organic carbon, total nitrogen and total phosphorus enrichment trend was observed in the treated soils due to biodegradation of the organic compounds supplied by USS. The decomposition of USS organic matter was presumably the main process responsible for the pH decrease in the USS-fertilized soils. There was no heavy metal accumulation in treated soils, and total heavy metal contents were below the corresponding maximum threshold concentrations set by European and Italian legislation. Increased availability of Cr, Cu, Pb and Zn was found in treated soils due to an increase in their extractable concentrations in the treatment period. The results of this study suggest that the environmental risks related to the accumulation and availability of heavy metals in agricultural soils fertilized with USS are limited when treatment observes recommended doses in agronomic treatment programs.

The influence of the usage of secondary fuels for Portland clinker production on the emission value of heavy metals from cement and concrete

The influence of secondary fuels components used for Portland clinker production on emission value of heavy metals is presented in this paper. Analyses and studies of hazardous substances emission (heavy metals) from cements and concretes were conducted according to standards developed by Technical Committee CEN TC 351. The contents of following heavy metals were analyzed: Cr, Zn, Cd, Pb, Co, Ni, Mn, Cu, Sr, Ba and P in secondary fuels used by cement industry in Poland for Portland clinker production. Total heavy metal contents in cements and their leaching from cements CEM I were studied. Leaching of heavy metals from CEM I-based concretes to environment was also determined. Obtained tests results allow to conclude that changes in technology of cement clinker production leading to the usage of waste materials and secondary fuels does not cause an increase in heavy metals emission in level, which requires qualifying cement as material, which has to be regularly controlled for harmfulness on man and natural environment.

Environmental Geochemistry of Heavy Metals and Plagioclase Background Enrichment Factor in Coastal Sediments at Lumpue - Parepare, South Sulawesi, Indonesia

Lumpue Beach is an urban area in Parepare Bay with a harbour, tourism, and a landfill site. The purpose of this research was to determine the provenance, level and distribution of heavy metals in coastal sediments. Surface sediment samples were analysed for grain size, mineragraphy, petrography and total heavy metal content (Cu, Zn, Pb, Co, Ni, Fe). The minimum-maximum background enrichment factor (EF) range was calculated from the plagioclase mineral content of trachyte porphyry and andesite. Weathering alteration was quite high in trachyte porphyry rocks; andesite mineragraphy produced predominantly sedimentary plagioclase (25-45%), hornblende (10-40%), and rock fragments (40-45%). The grab sampling method produced samples dominated by plagioclase (30-50%), hornblende (15-40%) and alkaline chemical conditions were important in Fe, Ni, Pb, Cd, Cr, and Cu enrichment. Enrichment of heavy metals was supported by the mesokurtic-very leptokurtic dynamic sorting characteristics of Lumpue beach, becoming very leptokurtic - platykurtic to the north (Parepare Bay). The enrichment factor (EF) of Pb > 1 was calculated from the concentration of various non-earth sources. The order of heavy metal concentration based on EF 0.5 ≤ EF ≤ 1.5 was Pb> Zn> Cr> Fe> Cu> Ni, with Cu ≤ 0.5, indicating heterogeneous heavy metal sources correlated with urban area, river and ultrabasic regional lithology, with Trachyte-andesite alteration, especially enrichment in heavy metals Ni, Cr, Cu. Index of geoaccumulation (Igeo) was in the ranges: uncontaminated to heavily contaminated for Fe; uncontaminated to moderately contaminated for Cu, Zn, Ni, Cr and Cd; and uncontaminated for Pb. The intensity of heavy metal contamination followed the direction of sedimentation from various sources. Euclidian Cluster distance showed heavy metal distribution patterns correlated with rivers passing through urban areas and with regional geological lithology.

An assessment of pH-dependent release and mobility of heavy metals from metallurgical slag

The paper presents the results obtained in pHstat leaching test and assesses the influence of pH changes and occurring processes on the release of heavy metals (Cd, Ni, Crtotal, Pb, Cu and Zn) from metallurgical slag in a zinc smelter. Additionally, the analysis of the potential maximum amount of element available for leaching and releasing in the batch leaching test was carried out. All the results of the leaching tests were compared with the total content of heavy metals in the material. In order to evaluate the chemical forms of elements, a sequential extraction study was also carried out. On the basis of test results obtained in pHstat test, a strong dependence of heavy metals leaching on the pH was found. The highest concentrations of the analysed elements were observed in acidic environment. For most metals, except for lead, an increase in the pH of the solution caused a decrease in their concentration. Lead showed an upward trend of release under alkaline conditions. A sharp increase of copper leaching at pH 10.5 was also observed. Based on the results of the study, cadmium can be considered the most mobile element from metallurgical slag. Chromium indicated the lowest degree of release.

Effect of antimonite mineralization area on heavy metal contents and geochemical fractions of agricultural soils in Gümüşhane Province, Turkey

In this study, the possible impacts of an antimonite mineralization area on agricultural lands with regard to heavy metal concentrations were examined. In this scope, surface soil samples (0–20 cm) were taken from a total of 27 locations including eleven from the Avliyana antimonite mineralization area (Torul, Gümüşhane-NW Turkey) and its surroundings, eleven from agricultural areas and five from the control area. Wet digestion method was used with aqua regia procedure for determining the total heavy metal (Cd, Cr, Cu, Ni, Pb, Zn) concentrations of the soil samples. The geochemical fractions of heavy metals in soil samples were determined by way of a sequential extraction procedure. The total heavy metal contents of the soils were determined as: Ni > Cr > Zn > Cu > Pb > Cd for control soils, Cr > Ni > Zn > Cu > Pb > Cd for agricultural soils and Zn > Cu > Ni > Cr > Pb > Cd for mining area soils. It was determined that especially the values of Zn (57.6 ± 6.2 μg/g) and Cu (52.4 ± 5.8 μg/g) were high at the mineralization area due to hydrothermal alterations that are effective in the formation of mineralization. It was put forth as a result of sequential extraction that the heavy metals examined excluding Pb were observed dominantly in the residual fraction for all data set. On the other hand, it was determined that the non-residual mobile fractions reached from 11% Cr to 78% Pb in control soils, from 20% Cd to 88% Pb in agricultural soils and from 24% Cd to 87% Pb in mineralization area soils. Contamination signals due to mineralization area were monitored by way of the metal content in mobile fractions. Even though the metal concentrations determined in short term are not alarming for agricultural production, signals were observed especially for Cd, Pb, Cu, Ni and Zn elements to be more mobile in mineralization area soils in the long term due to the impact of environmental factors thereby being carried over to and accumulating in agricultural soils. In conclusion, while it is expected that the metal inputs due to mineralization areas may increase in the future, it is suggested to include plant analyses in future studies for determining the impact of the amount of bioavailable metal.

Study on the factors affecting the spatial distribution of heavy metal elements

The contents of As, Cr, Cu, Zn and Pb in soils of the central urban area of Nanjing Jiangbei New area are analyzed by interpolation analysis. The effects of pH value, soil texture and heavy metal species on the contents of heavy metals are studied. The results show that the contents of heavy metals in the study area are more than 1.5 to 6.3 times of the soil background value in Jiangsu Province. The content of heavy metal Cr is 31.92∼95.38 mg/kg, and some areas have already exceeded the control value of the second type of construction land in China, 78 mg/kg. The pH value is inversely proportional to the total heavy metal content, which indicates that it is more difficult to enrich heavy metal ions in alkaline environment. The soil texture in this area is dominated by sand grains, and the spatial distribution of sand grain content decreases from southwest to northeast. The clay content is positively correlated with the heavy metal content except Zn. The main forms of the five kinds of heavy metals in soil are residues, reaching 73.86%∼88.15%, and with the increase of heavy metals content in soil, the proportion of residual decreases.

Оценка загрязненности почв тяжелыми металлами вокруг Дашкесанского горно-обогатительного комбината

The article is devoted to the results of the determination and assessment of the content of heavy metals (HM) in the soil around the Dashkesan mining and processing factory of the Azerbaijan Republic. Combine open-pit mining method produces iron ore with its subsequent enrichment by flotation. Quarry blasting, transportation and crushing of ore by flotation swallowing; open pit and waste rock dumps after ore concentration (heaps) are the main sources of environmental pollution. Air currents and meltwaters contaminants HM fall into the soil. By the method of atomic absorption spectrometry in soil, the total content of Pb, Co, Cd, Cr, Cu, Zn was determined. The assessment of soil contamination by heavy metals was carried out by the Clarke number, the MPC and the total amount (Zc) of the TM. According to the Pb, Cd, Cu, Zn content, the soils are estimated as unpolluted, and according to the Co and Cr content - extremely polluted (MPC exceedance is more than 4 times). According to the total content of HM (Zc), soils are also assessed as extremely polluted. There is no regularity in the distribution of HM content in the soil around the source of pollution. As the distance from the source of contamination increases, the HM content in the soil changes spontaneously, which is a result of the influence of orographic and geological factors.

Variation of green liquor dregs from different pulp and paper mills for use in mine waste remediation.

The geotechnical, chemical, and mineralogical properties of green liquor dregs (GLDs) generated as byproducts from five paper mills were investigated to assess their buffering and heavy metal immobilization capacities and their roles as water and oxygen barriers. One type of GLD was further studied to test the effects of the retrieval process and the storage, drying, and hydration of GLD. The high water retention capacity of the GLDs is valuable for limiting O2 diffusion. Laboratory results showed that the GLDs had hydraulic conductivities of 3.7 × 10-9-4.6 × 10-8 m/s and varied regularly in plasticity. The chemical and mineralogical compositions of the GLDs varied greatly, reflecting the raw material used to produce paper and the process used to retrieve GLDs. Although they had high total heavy metal contents, none of the leached elements from the GLDs (L/S 10 cm3/kg) exceeded the European Union's limits for landfills of non-hazardous waste. The GLDs exhibited high buffering capacities. In a supplementary test, the buffering capacities varied (0.0041-0.0114 M H+/g GLD) over 72 d after acid was added to the GLD. Changing the filtration process did not greatly affect the GLDs' properties but mainly affected the hydraulic conductivity, total heavy metal contents and sulfur content. Analyzing the storage of GLDs is necessary in the mining industry because remediation measures require large amounts of material over short periods. The buffering capacity of the dried GLD decreased slightly. The effect of dewatering caused by the mixing of 2% Na-lignosulfate with GLD (w/w) was low.

Comparison of the Characteristics of Fly Ash Generated from Bio and Municipal Waste: Fluidized Bed Incinerators.

European solid waste incinerator plants still primarily use grate furnace technology, although circulating fluidized bed (CFB) technology is steadily expanding. Therefore, few investigations have reported on the environmental assessment of fly ash from fluidized incinerators. This research project aims to integrate information on fly ash derived from the combustion of municipal solid waste (FA1) and biomass (FA2) in fluidized bed incinerator facilities. Fly ash samples were comparatively analyzed by X-ray diffraction (XRD), X-ray fluorescence spectroscopy (XRF), scanning electron microscopy (SEM), and inductively coupled plasma optical emission spectroscopy (ICP-OES) to study the mineralogy, morphology, total heavy metal content, and leaching behavior, respectively. The analysis revealed that the two types of fly ash differ in their characteristics and leaching behavior. The concentration of most of the heavy metals in both is low compared to the literature values, but higher than the regulatory limits for use as a soil conditioner, whereas the high contents of Fe, Cu, and Al suggest good potential for metal recovery. The leaching ability of most elements is within the inert waste category, except for Hg, which is slightly above the non-hazardous waste limit.

Laboratory Melting of Late-Winter Urban Snow Samples: The Magnitude and Dynamics of Releases of Heavy Metals and PAHs

Laboratory snow melting experiments were conducted with actual late-winter snow samples, collected just before the final snowmelt, in two similar northern Swedish cities, Luleå and Umeå, to investigate releases of the selected heavy metals (HM) (Cu, Pb, Zn, and Cd) and 16 USEPA PAHs from melting snow. Metal concentrations were determined in three fractions: total, dissolved, and truly dissolved (defined as the fraction passing through a 3-kMWCO ultrafilter). Total HM concentrations in snowmelt were rather high at both sites and reflected the accumulation of pollutants in the roadside snowbanks over a period of about 5 months: Cd = 0.43, Cu = 303, Pb = 41.9, Zn = 817 (μg/l), and TSS = 2000 (mg/l) in Luleå samples and Cd = 1.87, Cu = 905, Pb = 165, Zn = 3150 (μg/l), and TSS = 4800 (mg/l) in Umeå samples. The difference between metal and TSS concentrations at the two sites of similar characteristics was attributed to a smaller volume snowbank in Umeå. The dissolved HM concentrations represented relatively small fractions of the total concentrations (0.3–6.9% in Luleå and 0.01–3.1% in Umeå). The truly dissolved fraction represented 71–90% of the dissolved fraction in Luleå and 74–98% in Umeå. At both sites, the dissolved fractions exhibited preferential elution from the laboratory snow piles. The PAHs studied (16 US EPA PAHs) were mostly particulate bound, with only 5–12% of the total burden contributed by the meltwater, and most dissolved concentrations below the reporting limits. PAH concentrations in the Luleå samples were about one-third to one-fourth of those in Umeå. In general, the releases of PAHs from the snowbank were delayed, compared with releases of meltwater, and showed similar release patterns as TSS.

Simulating heavy metal concentrations in an aquatic environment using artificial intelligence models and physicochemical indexes

Although heavy metal monitoring campaigns are established worldwide, it is still difficult to model heavy metals in aquatic environments with limited monitoring data. In this study, surface water physicochemical indexes and heavy metal concentrations were measured in a drinking water source in the Taihu Lake region, China. Afterwards, indexes including water temperature, pH, suspended matter, turbidity, and total nitrogen, nitrate nitrogen, ammonia nitrogen, total phosphorous, orthophosphate and permanganate index were used to simulate dissolved, particulate and total heavy metal concentrations using artificial neural network (ANN) and support vector machine (SVM) models. Sensitivity analysis showed that simulated heavy metal concentrations were most sensitive to pH. Thereafter, quick simulation models based on five sensitive parameters (pH, suspended matter, water temperature, total phosphorus and permanganate index) allowed for quick simulations of heavy metal concentrations were built. Both ANN and SVM quick simulation models simulated particulate heavy metal concentrations well with most Nash-Sutcliffe efficiency coefficients >0.8. Models performed worse when simulating dissolved and total heavy metal concentrations. Results demonstrate that artificial intelligence models like ANN and SVM are alternative ways to simulate heavy metal concentrations with limited monitoring data. Furthermore, sensitivity analysis may help to identify key factors affecting heavy metal behavior, and to improve environmental monitoring campaigns and management strategies.

Chemical speciation and potential ecological risk assessment of heavy metals in volcanic rocks of Southern Qinghai, China

ABSTRACTSeven volcanic rocks samples were collected from Southern Qinghai to analyze chemical speciation and migration behavior of heavy metals by sequential chemical extraction procedure and column leaching test. The geo-accumulation index, ecological risk index and the risk assessment code were applied to assess the heavy metal pollution and potential environmental effects in this area. Results revealed that the total concentrations of heavy metals did not exceed the background values in soil of this area. Most of the samples produced acid rock drainage. The order of heavy metal migration and transformation sequence in the volcanic rocks of Zhiduo region was Cd > Pb > As = Cu = Zn = Mn based on the geo-accumulation index and Cd caused heavy pollution, which was also confirmed by the leaching test. Moderate potential ecological risk posed by heavy metals occurred in the study area based on the potential ecological risk index. Cd contributed to most of ecological risk while the remaining heavy metals (except As) exerted medium to high risks to the environment according to the risk assessment code evaluation results. In summary, volcanic rocks possessed potential risks to the surroundings due to potential release of heavy metals. Cd that caused the pollution should be paid special attention.

Effects of residence time on characteristics of biochars prepared via co-pyrolysis of sewage sludge and cotton stalks

Conversion of sewage sludge and agriculture straws into biochars via co-pyrolysis is a promising strategy for the safe disposal and reuse of sewage sludge. In this study, biochars were prepared via the co-pyrolysis of sewage sludge and cotton stalks (1:1, w/w) with different residence times (30–150 min). The influence of residence time on the physicochemical properties and surface characteristics of the biochars were studied. Meanwhile, the chemical forms of six heavy metals (Pb, Cu, Zn, Cr, Ni, and Cd) in the biochars were investigated with BCR (Community Bureau of Reference)-recommended extraction procedures and the potential environmental risks of heavy metals were assessed. It was found that prolonged residence times increased the pH and ash contents of the biochars, but these conditions decreased the C, N, and H contents. The surface areas of the biochars increased in the range of 30 min to 90 min, while values decreased in the range of 90 min to 150 min. Although more heavy metals were volatilized or transferred into biogas with the increasing residence time, a considerable amount was retained in the biochars, and this resulted in an increase in the total concentrations of heavy metals. The BCR extraction experiments confirmed that the heavy metals became immobilized in the biochars following the transformation of heavy metals from active chemical forms to stable ones. The results of risk evaluation indicated that prolonged residence times decreased the potential environmental risks of heavy metals in the biochars.

Speciation analysis and dynamic absorption characteristics of heavy metals and deleterious element during growing period of Chinese peony

The heavy metals and deleterious element (Pd, Cd, Cu, As, and Hg) in Chinese peony (Paeonia lactiflora Pall.) were determined by Tessier’s sequence extraction method. Pb mainly existed in carbonate fraction. The main fraction of Cd in different tissues and different month is quite different. Cu mainly exists as exchangeable carbonate fractions. Five forms of Hg all exist in leaf, stem, and root. The total absorbable fraction of Pd, Cd, Cu, As, and Hg was different in different tissues. The total content of heavy metals can migrate from different tissues and the content of different speciation of heavy metal also can change during the growing period of plants. The results showed that different parts of plants and different elements resulted in different distribution and mobility. Base on this, it is more scientific and reasonable to clarify the migration and enrichment and to analyses the speciation of heavy metals during growing period of plant medicine. It is more scientific and reasonable to clarify the migration and enrichment, and to analyses the speciation of heavy metals during growing period of plant medicine.

Soil Quality Analysis in Newly Increased Cultivated Land

In order to explore soil physical-chemical properties and water quality in Bailiang town, Heyang county of Shaanxi Province, the soil physical-chemical properties of newly increased cultivated land, the water heavy metal contents of chromium, copper, zinc, arsenic, selenium, cadmium, mercury and lead of Yellow River water and groundwater in the project area were measured. The results showed that the pH value, total salt content and heavy metal content of the Yellow River and groundwater were all in line with the farmland irrigation water quality Standard, which could guarantee irrigation use. The type of soil in the 0∼30 cm was sandy loam, the bulk density of 0∼30 cm soil layer was 1.52 g cm−3, and the saturated hydraulic conductivity was 229.41 cm d−1, which could meet the needs of planting soil quality requirements, but sandy loam soil with large saturated water conductivity was easy to leak water and fertilizer. Meanwhile, the content of exchangeable calcium of 0∼30 cm soil layer was in a very rich state(38.6∼90.1 cmol kg -1), and the content of available potassium (36∼128 mg kg−1)and effective boron(0.56∼0.89 mg kg−1)were moderate, the content of organic matter(1.06∼2.65 g kg−1), total nitrogen(0.18∼0.33 g kg−1), available phosphorus(3.2∼8.4 mg kg−1) and available silicon content(41.0∼68.6 mg kg−1)were in a state of lack. These results indicate that the organic fertilizer, green manure, straw and small amounts of fertilizer could be used to increase the content of organic matter, and other nutrient elements in the cultivated layer. It was recommended to design the loess tillage layer and plow pan layer, which played the role of water retention and fertilizer retention, and was suitable for the growth of aquatic crops.

Impact of some industrial solid wastes on the growth and heavy metal uptake of cucumber (Cucumis sativus L.) under salinity stress

This study was conducted to investigate the effect of industrial solid wastes (ISWs) and salinity on growth and heavy metals uptake by cucumber (Cucumis sativus L.). The soil was treated with 5% and 10% of the ceramic factory (CFW), stone cutting (SCW) and sugar factory (SFW) wastes. Plant of cucumber was grown under greenhouse conditions in control and ISWs treated soils and stressed with electrical conductivities of 0, 4 and 8 dS m−1. Plants were harvested after 2 months and separated into root, shoot, and fruit. Then, dry weights and heavy metals contents in each fraction of plants were determined. The addition of all ISWs in soil increased total heavy metals content in the soil. In all treatments, growth parameters of cucumber decreased when irrigated with saline waters. As compared to control soil, the addition of CFW and SCW to soil decreased plant dry weight, while, it was improved with the addition of the SFW. The result of plant analysis showed that there was an increase in the contents of heavy metals (except Cr) in all parts of cucumber with the addition of ISWs. Salinity decreased the content of Zn uptake and increased another heavy metal uptake by all parts of the plants. The application of ISWs and salinity did not show a significant effect on bioconcentration (BCF) and transfer factor (TF) of heavy metals in plants. The health risk index (HRI) values of all heavy metals for both adults and children were found to be less than 1, so, the health risk of heavy metal for people who consume cucumber grown in these industrial areas was generally assumed to be safe.

Assessment of total soil contamination with heavy metals in the coastal area of the cape peschany

In the autumn of 2018, in the coastal zone of the Caspian region, namely, in the area of Cape Peschany, scientific field studies of the state of the soil were carried out. 7 test sites (TS) were investigated.Studied more than 30 soil samples taken from depths of 0-5 and 5-20 cm spectrophotometer laboratoryHACH DR-2400 (USA) determined the total contents of heavy metals (HM). For analyz ephase threetotal soil pollution (TSP) or TS, using different approaches, the used value of the content of chemicalelements in the background area TS-the background. The soil of the Karakia-Karakol reserve was used asa background. Only the value of KC>1 was taken into account in the calculation of ZC. Perhaps in thisregard, for TS-3 (garden), the lowest total soil pollution index was obtained, including negative valuesof ZC(r). The results of the calculations, only on TS-2, ZСТ=16.5 level of contamination moderate threaton the remaining TS and within the acceptable level. Statistical processing of the results in the programStatistica 10 showed that the criterion of Kruskal-Wallis is statistically significant for the elements of Cr,Cd, Cu and Co.Key words: Caspian Sea, Cape Peschany, soil, heavy metals, total pollution.

Relation between changes in organic matter structure of poultry litter and heavy metals solubility during composting

Poultry litter (PL) is widely used as fertilizer because of its rich N, P and Ca content. When PL is applied to previously untreated soil, it is a potential contaminant. Composting is an alternative for stabilizing organic and mineral components. This study aimed to elucidate the structural changes and its influence on the solubility of heavy metals in poultry litter during the first 30 d of composting, which is the period when the most intense transformations occur. For this analysis, the transformation dynamics of the organic structures and the availability of mineral elements were studied via spectroscopic characterization, total heavy metal content determination and chemical fractionation at three composting times (0, 15, and 30 d). During composting, the material's aromaticity increased, while its aliphaticity decreased, and the hydrophobicity index increased as the polarity decreased. These results indicate that during the first 30 d, PL composting occurs via transformation of the most labile structures (carbohydrate, peptide and fatty acid fragments), thereby preserving the most stable and least functionalized structures. Composting increased the concentrations of Cu, Cr, Pb and Zn and the transformation of CAlk-O and CAlk-di-O associated with peptides and carbohydrates and favored solubilizing and leaching a water-soluble fraction rich in these compounds. The labile fractions of Fe and the humified organic matter fractions of Cu, Fe, Mn, Zn, and Al increased. The structural changes reduced heavy metal solubility, thus indicating that after 30 d of composting, the heavy metal contamination risk is low.

Geoecological analysis of Shkota island landscapes (the Sea of Japan)

The study of Shkota Island (Peter the Great Bay, the Sea of Japan) allows us to assess the modern geosystem condition. High-closed broad-leaved forests are found mainly on the northern and western slopes, whereas scattered and scrub broad-leaved forests, bush, semi-bush and grass communities are found in the south and east. The soil-vegetation cover shows the technogenic impact evidence like on other islands previously belonging to the military department. The landscape structure is composed of 16 morphological units. The total territory is a mountain landscape class, with about 82% of the area belonging to a low-mountain landscape subclass, and 12.35%, to a coastal subclass. Beach accumulative landscape developed on sandy-pebble coastal sediments without soil-vegetation cover is located in the north. Uncontrolled recreational activity has become recently the major factor of anthropogenic transformation of natural complexes. High number of visitors and campsite activity increase the fire danger. Ground fires disturb natural ecosystem functioning. The vegetation, lichens and soils bear the evidence of fire impact. Intense mechanical impact on the soil-vegetation cover occurs in the campsite areas. Because of low depth and high skeletal soil, the bulk of island land is prone to erosion. Trampling leads to active sheet soil erosion and destruction of grass-bush layers. The total content of heavy metals in accumulative-humus layers makes up a small proportion of the approximate permissible concentration. Recreational activity, in particular, burning of solid waste explains high concentration of heavy metals in the west. Copper concentration increases by an order of magnitude there in comparison with ones from the other island parts. The copper concentration comes close to the approximate permissible concentration or may outnumber it, considering an analytical error. Zinc concentration outnumbers the approximate permissible concentration without including analytical error.
 Intense anthropogenic impact disturbs the spatial landscape structure and changes material-energy flows resulting in decreasing landscape diversity. Though Shkota Island geosystems have experienced high anthropogenic influence since the beginning of the XXth century, today we observe reliable restoration of destroyed ecosystems. These areas are being actively covered with grass-bush communities dominating by Lespedeza bicolor and Artemisia gmelini, which boosts humification and humus accumulation. Saplings of broad-leaved trees spring there. But periodic ground fires make stable forest restoration difficult.

Distribution and availability of heavy metals in soils near electroplating factories.

Comprehensive understanding of the influence of soil properties on the potential availability of heavy metals could facilitate soil environment management. This study investigated the distribution of heavy metals and their potential availability in paddy and vegetable fields around electroplating factory outlets and irrigated with its wastewater. The potential availability was assessed using secondary phase fraction (SPF) of heavy metals, including acid-soluble, reducible, and oxidizable fractions resulting from BCR sequential extraction procedure. In total, 94 of topsoil samples (0-20 cm) were collected. Total and SPF concentrations of heavy metals as well as soil physicochemical properties were determined. Multivariable statistical analyses (i.e., principal component analysis (PCA) and redundancy analysis (RDA)) were employed. Results showed that total and SPF concentrations of heavy metals in soil decreased (P<0.05) as sampling distance away from the electroplating factories increased, suggesting that sampling distance was the major parameter that affected gradient variations of both total and potential availability of soil heavy metals. According to PCA, soil samples distributed on the PCA axis representing anthropogenic effect, illustrating that the variation of soil properties resulted from irrigation with electroplating wastewater. RDA and stepwise regression indicated that soil Mn oxides, amorphous Fe oxides, silt content, and pH could explain 68.8% and 43.5% of the variation of SPF concentration in paddy and vegetable garden soil, respectively, suggesting they were the most important factors influencing the potential availability of heavy metals in soils. The potential availability of heavy metals in soil was positively correlated with soil Mn oxides but negatively associated with soil amorphous Fe oxides, indicating that Mn oxides enhanced the potential availability of heavy metals while amorphous Fe oxides reduced the potential availability.