Bioremediation of oil-contaminated soils by composting

Composting oil-contaminated soils under field conditions with the simultaneous optimization of their physicochemical and agrochemical parameters revealed the high efficiency of the soil purification, including that from benz[a]pyrene. The application of fertilizers and lime favored the intense development of indigenous microcenoses and the effective destruction of the oil. During the 95-day experimental period, the average daily rate of the oil decomposition was 157 mg/kg of soil. After the completion of the process, the soil became ecologically pure.     

Accumulation of heavy metals in oil-contaminated peat soils

X-ray fluorescence and X-ray radiometry represent easy and simple methods to determine concentrations of heavy metals in the ash of peat soils contaminated with oil and can be applied for soil monitoring purposes. Oil spills on peat bogs produce two contamination zones differing in the composition of heavy metals. In the zone of primary contamination, the peat surface is covered by a bitumen crust with V, Ni, Sr, Ba, Ce, and La accumulating there. This zone adjoins the zone of secondary peat contamination, where heavy alkaline-earth metals (Sr, Ba) and lanthanides (Ce and La) are accumulated to a lesser extent. Biological preparations recommended for remediation of oil-contaminated peat soils should be tolerant to high concentrations of heavy metals, particularly, V, Ni, and Ba that are present in the oil contaminated soils in relatively high amounts.     

Ecological evaluation of artificial soils treated with phosphogypsum

An attempt to set up ecologically acceptable concentrations of toxic components contained in phosphogypsum was made for soils of different land uses. For this purpose, an experimental ecological evaluation of a standard soil mixture (model artificial soil ISO 11268-1) treated with phosphogypsum was performed. Both positive and negative effects of the phosphogypsum components were found. Thus, a significant increase in the biomass of lawn grasses was observed in the model soil with the phosphogypsum content of less than 3.3%. In the soil containing more than 6.8% phosphogypsum, the concentrations of Sr and F exceeded the maximum permissible values and adversely affected the living organisms. According to the basic ecological norms, the allowable content of phosphogypsum should be ≤2.0% for the soils of specially protected natural areas; ≤6.8% for agricultural and urban soils; and ≤9.6% for the soils of forest, water management, and transport lands.     

Assessing the biological activity of oil-contaminated soddy-podzolic soils with different textures

The respiratory activity features in oil-contaminated soddy-podzolic soils of different textures have been studied. Unidirectional processes occur in contaminated loamy and loamy sandy soddy-podzolic soils; their intensities depend on the soil parameters. The mineralization rates of the oil products and the activity of the microflora in loamy soils exceed the corresponding parameters for loamy sandy soils. The long-term impact of oil and its transformation products results in more important disturbances of the microbial community in light soils. It has been shown that light soils containing 9% oil require longer time periods or more intensive remediation measures for the restoration of soil microbial cenoses disturbed by the pollutant.     

Oil hydrocarbon migration in soils of the northeast of Sakhalin Island

The results of vertical and lateral intrasoil migration of oil hydrocarbons (OHCs) in podzolic, techno-podzolic, brown forest, alluvial meadow-bog, and peat gley soils of Sakhalin Island are presented in this article. An estimation of the spatial distribution of oil hydrocarbons on the surface of oil spills, industrial sites, and natural discharges of oil is made. The factors influencing the structure of contamination halos and migration intensity of oil hydrocarbons in soils are considered.     

Remediation of oil-contaminated soil using the CLEANSOIL technology

Approbation data of the innovative CLEANSOIL technology of soil purification after oil pollution are given. Drainage pipes filled with an adsorbent with microorganisms placed in the soil are used. It is revealed that the content of hydrocarbons under the technological constructions (metal columns and reservoirs) rises in comparison with the open oil-polluted areas. It is shown that the oil is destroyed quicker under the constructions versus in the open areas. The microorganisms better assimilate the n-alkanes with C₁₄ chains than the C_32–40 hydrocarbons. The application of a combined technology based on the sorption and reduction of the hydrocarbons by microorganisms makes it possible to quickly reduce the soil pollution by oil products without the soil cover’s disturbance.     

Treatment of Cr(VI)-spiked soils using sulfur-based amendments

The objective of this research was to assess the hexavalent chromium (Cr(VI)) reducing efficiency of sulfur-based inorganic agents including calcium polysulfide (CPS), iron sulfide (FeS), pyrite (FeS₂) and sodium sulfide (Na₂S) in three soils. An alkaline soil (soil 1), a neutral soil (soil 2) and a slightly acid soil (soil 3) constituted the investigated soils. The soils were spiked with two levels of Cr(VI) (100 and 500 mg Cr(VI) kg^?1 soil) and incubated at field capacity (FC) for one month. Then, CPS, FeS, FeS₂ and Na₂S were added at 0, 5 and 10 g kg^?1 and the concentrations of exchangeable Cr(VI) were measured after 0.5, 4, 48 and 168 h in a batch experiment. The pH and organic carbon content of the soils played predominant role in Cr(VI) self-reduction by the soil itself. Complete self-reduction of Cr(VI) from soils 1, 2 and 3 was achieved at maximum Cr(VI) levels of 1, 50 and 500 mg kg^?1, respectively. Therefore, the concentration of Cr(VI) should not exceed the given levels in order to ensure that Cr(VI) is not released into the environment from contaminated sites. Moreover, decreasing pH in the alkaline soil caused significant increase of Cr(VI) reducing efficiency. Na₂S, CPS and FeS, in contrast to FeS₂, were efficient Cr(VI) reducing agents in all three soils. For all added amendments the following order of Cr(VI) reducing capacity was observed: Na₂S > CPS > FeS > FeS₂ in soil 1, Na₂S ? CPS ~ FeS > FeS₂ in soil 2 and Na₂S ? FeS > CPS ~ FeS₂ in soil 3.     

Geochemical characterization of soils of the eastern coast of the Northern Sakhalin Lowland

Concentrations of heavy metals (HMs) were determined in soils of the eastern coast of the Northern Sakhalin Lowland. The total contents of HMs and their distribution in the studied soils differed from those in the world soils. Thus, barium and mercury concentrations exceeded clarke values for the world soils. The reserves of mobile forms of microelements were found to be low. Significant biogenic accumulation in organic soil horizons in the process of soil formation was found for copper, arsenic, and barium.     

Content of some organic and inorganic pollutants in soils of southern part of Sakhalin Island

The article is dedicated to analyzing the content and distribution of oil hydrocarbons, benz(a)pyrene, and heavy metals in the soils of the southern part of Sakhalin Island. The investigations were conducted in 2003–2010. A dynamical increase in the content of ecotoxicants in soils has been shown. The similar character of the accumulation of oil hydrocarbons, benz(a)pyrene, and heavy metals in the soils has been determined and indicates the possibility of the aerial transmission of pollutants from existing nearby sources.     

Ecological assessment of soils in high-mountain landscapes of northeastern part of the Greater Caucasus (Azerbaijan)

The current state of soils and bioproductivity of high-mountain pastures and hayfields in the northeastern part of Great Caucasus within Azerbaijan were studied, and the quality assessment of soils was performed. The ecological evaluation of soils was based on special assessment scales and soil bonitet scores. The soils suitable for the development of meadow vegetation were identified. The highest score (89 points) was given to mountainous meadow chernozemlike soils (Eutric Mollic Leptosols); these soils are most suitable for pasturing. Mountainous meadow soddy soils (Dystric Umbric Leptosols) ranked second (76 points). Mountainous meadow-steppe soils (Eutric Mollic Leptosols) were estimated at 72 points; these soils are suitable for plant communities of subalpine meadows. Mountainous meadow soddy–peaty soils (Brunic Umbric Leptosols) had the lowest score of 68 points mostly because of the excessive precipitation against the background of relatively low mean annual temperature limiting the biological productivity of alpine meadows.     

High-pressure liquid chromatography of benzo(a) pyrene and benzo (ghi) perylene in oil-contaminated shellfish.

A high-pressure liquid chromatographic procedure is described for the determination of benzo(a) pyrene and benzo(ghi) perylene. These polynuclear aromatics are extracted with acetonitrile and partitioned into petroleum ether, the petroleum ether is removed, and the residue is saponified. The compounds are purified and isolated by passing the residue through a silica gel column and a high-pressure liquid chromatographic column, and detected by their ultraviolet absorption. Recoveries of standards through the procedure averaged 104%.     

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.     

土壤放射性污染的生态效应及生物修复

放射元素半衰期长,放射性污染物进入土壤会危害农业生态环境,威胁人类的健康和其他生物的生存。本文介绍了土壤放射性污染的来源及环境生态效应,阐述了土壤放射性污染的生物修复途径、修复方法、修复机理和影响修复效果的因素,指出生物修复土壤放射性污染的关键,即利用植物基因工程技术筛选核素积累植物和超积累植物,通过构建基因工程技术筛选、改造对放射性核素具有高度亲和力且对环境友好的微生物。     

Evaluation of bacterial strains isolated from oil-contaminated soil for production of polyhydroxyalkanoic acids (PHA)

Samples of eight geographically distinct soils contaminated with crude oil were screened for polyhydroxyalkanoic acid (PHA) producing bacterial strains. Twenty three bacterial strains were able to accumulate PHA when sodium gluconate or sodium octanoate was used as the sole carbon source. Biochemical tests and 16S rRNA sequencing identified bacteria of the genera Pseudomonas, Acinetobacter, Sphingobacterium, Brochothrix, Caulobacter, Ralstonia, Burkholderia and Yokenella. Three of the bacterial strains have never been reported to produce PHA. The phylogenetic analysis of the PHA synthase (phaC) gene of these bacteria showed a close homology with the phaC gene of different Pseudomonas species.This study indicates that stressed environments like oil-contaminated sites can be potential sources of medium-chain-length PHA producers.     

Evaluation of bacterial strains isolated from oil-contaminated soil for production of polyhydroxyalkanoic acids (PHA)

Samples of eight geographically distinct soils contaminated with crude oil were screened for polyhydroxyalkanoic acid (PHA) producing bacterial strains. Twenty three bacterial strains were able to accumulate PHA when sodium gluconate or sodium octanoate was used as the sole carbon source. Biochemical tests and 16S rRNA sequencing identified bacteria of the genera Pseudomonas, Acinetobacter, Sphingobacterium, Brochothrix, Caulobacter, Ralstonia, Burkholderia and Yokenella. Three of the bacterial strains have never been reported to produce PHA. The phylogenetic analysis of the PHA synthase (phaC) gene of these bacteria showed a close homology with the phaC gene of different Pseudomonas species.This study indicates that stressed environments like oil-contaminated sites can be potential sources of medium-chain-length PHA producers.     

Agroecological evaluation of soils suitable for viniculture on the southeastern macroslope of the Great Caucasus (Azerbaijan)

Data on the agroecological evaluation of soils suitable for viniculture on the southeastern macroslope of the Great Caucasus in Azerbaijan are discussed. The quality of major soil types and subtypes has been assessed on the basis of special scales developed for the particular soil properties. The agroecological classes of soils have been specified, and the limiting and favorable ecological factors for winegrowing have been determined. On this basis, the areas with best ecological conditions for the development of viniculture have been outlined.     

Estimation of charcoal (char) in soils

Abstract

A method for the semiquantitative estimation of charcoal (char) in soils is reported. The technique, performed on the <53 μm fraction of soils, utilizes the highly aromatic nature of char and its relative stability to two hours of high energy ultraviolet photo‐oxidation compared to other soil carbon fractions. The proportion of char in the <53 μm fraction is estimated as the aromatic carbon (C) content measured by solid‐state nuclear magnetic resonance spectroscopy using cross polarization and magic angle spinning. Corrections are made for the underestimate of aryl C by the cross polarization method in highly condensed aromatic char structures and for the small lignin content that occurs in some samples. Evidence is also provided for the occurrence of >90% of soil char in the <53 μm fraction. Because of the assumptions used, estimates of char by this approach must be considered to be semiquantitative, but are conservative and provide estimates of the minimum char content of a soil.     

Decomposition of nitrilotriacetate (NTA) in soils

The trisodium salt of nitrilotriacetic acid (NTA) has been proposed as a substitute for phosphate in detergents. The decomposition of this chelating agent in soils was studied by performing analyses for NTA and inorganic nitrogen after incubation of NTA-treated soils for various times. The results showed that NTA is readily decomposed by soil micro-organisms under aerobic or anaerobic conditions and that NTA-nitrogen is converted to nitrate under aerobic conditions. The latter finding indicates that use of detergents containing NTA may lead to nitrate enrichment of water resources.     

Agroecological evaluation of soils as a basis for controlling soil-ecological risks (by example of soils of the dry steppe zone in the Volgograd region)

This article characterizes the soil-ecological conditions of the Romashkovskii breeding farm area in Pallasovskii district, Volgograd oblast, which is located in the dry steppe zone. An agroecological assessment is given for the farm’s soils using the Karmanov’s method of calculating soil-ecological indices and taking into account the specificity of agricultural crops. The possibility of using this evaluation as a basis for controlling soil-ecological risks in cropping is considered.     

The spatial variability of the oil contamination level in technogenic transformed podzolic soils at the northeast of Sakhalin Island

The vertical and lateral microvariability of total petroleum hydrocarbon (TPH) in technogenic soils is considered in this work. An autocorrelation and cross-correlation analysis of the TPH along a transect in the lateral direction is carried out. Statistical parameters of TPH for various industrial sites, oil spills, and natural exits are described and the normal or lognormal law of distribution of petroleum hydrocarbons in technogenic soils is confirmed. The percentage of the total spatial variability of TPH contributed by hierarchical sampling levels (10 cm, 0.25 ha, and 20 km2) is estimated. Planning the volumes of the samples that are necessary for an assessment of the average level of pollution in soils for separate sites and the entire territory of the oil field is carried out.