Specific features of oil biodegradation in meadow-chestnut soils of the Stavropol region (model experiment)

Oil biodegradation in oil-contaminated meadow-chestnut soils under the impact of different biological preparations was studied in a model experiment. The soils differed from one another in the age of contamination and in the presence/absence of the stage of preliminary biological remediation. Background uncontaminated soils served as the control. To characterize oil degradation, the indices of basal respiration (BR) and dehydrogenase activity (DA) and data on oil concentrations in the soil were applied. It was shown that the most complete biodegradation of oil takes place in the soils with recent oil contamination in comparison with the soils contaminated with oil for 6.5 and 19.5 months. Maximum BR values were observed in the soils contaminated with oil for 19.5 months, whereas maximum DA values were observed in the soils contaminated with oil for 6.5 months. According to the multivariate analysis of variance, the major factors affecting the rate of oil biodegradation were the age of oil contamination, the biological preparation applied, and the presence (or absence) of the stage of preliminary biological remediation. These factors specified 18, 72, and 3% of the total variance of the residual oil content in the samples, respectively. The type of the applied biological preparations had the major effect on the BR and DA indices specifying 63 and 53% of their total variances, respectively. The results obtained in this study can be used as recommendations for remediation of oil-contaminated soils in the Stavropol region.     

The Effect of Lignite and Comamonas testosteroni on Pentachlorophenol Biodegradation and Soil Ecotoxicity

Biodegradation of pentachlorophenol (PCP) in soil by autochthonous microflora and in soil bioaugmented by the bacterial strain Comamonas testosteroni CCM 7530 was studied. Subsequent addition of lignite, an abundant source of humic acids, has also been investigated as possible sorbent for PCP immobilization. Biodegradation of PCP and number of colony-forming units were determined in the three types of soil, haplic chernozem, haplic fluvisol, and haplic arenosol, freshly spiked with PCP and amended with tested sorbent. The enhancing effect of sorbent addition and bioaugmentation on PCP biodegradation depended mainly on the soil type and the initial PCP concentration. Microbial activity resulted in biotransformation of PCP into certain potentially toxic substances, probably lower chlorinated phenols that are more soluble than PCP, and therefore more toxic toward present biota. Therefore, it was necessary to monitor soil ecotoxicity during biodegradation. Addition of lignite resulted in a significant improvement of PCP biodegradation and led to a considerable decrease of soil toxicity especially in bioaugmented soils. The method could potentially serve as a promising technique in remediation technology for reducing high initial PCP content in contaminated soils.     

黄河三角洲土壤土著菌的石油烃降解潜力

The bioremediation potential of bacteria indigenous to soils of the Yellow River Delta in China was evaluated as a treatment option for soil remediation. Petroleum hydrocarbon degraders were isolated from contaminated soil samples from the Yellow River Delta. Four microbial communities and eight isolates were obtained. The optimal temperature, salinity, pH, and the ratios of C, N, and P （C：N：P） for the maximum biodegradation of diesel oil, crude oil, n-alkanes, and polyaromatic hydrocarbons by indigenous bacteria were determined, and the kinetics changes in microbial communities were monitored. In general, the mixed microbial consortia demonstrated wider catabolic versatility and faster overall rate of hydrocarbon degradation than individual isolates. Our experimental results demonstrated the feasibility of biodegradation of petroleum hydrocarbon by indigenous bacteria for soil remediation in the Yellow River Delta.     

Highly Efficient Removal of Cu(II) from Aqueous Solution by Using Graphene Oxide

Chemical reagents used by the textile industry are very diverse in their composition, ranging from inorganic compounds to polymeric compounds. Strong color is the most notable characteristic of textile effluents, and a large number of processes have been employed for color removal. In recent years, attention has been directed toward various natural solid materials that are able to remove pollutants from contaminated water at low cost, such as sugarcane bagasse. Cell immobilization has emerged as an alternative that offers many advantages in the biodegradation process, including the reuse of immobilized cells and high mechanical strength, which enables metabolic processes to occur under adverse conditions of pH, sterility, and agitation. Support treatment also increases the number of charges on the surface, thereby facilitating cell immobilization processes through adsorption and ionic bonds. Polyethyleneimine (PEI) is a polycationic compound known to have a positive effect on enzyme activity and stability. The aim of the present study was to investigate a low-cost alternative for the biodegradation and bioremediation of textile dyes, analyzing Saccharomyces cerevisiae immobilization in activated bagasse for the promotion of Acid Black 48 dye biodegradation in an aqueous solution. A 1 % concentration of a S. cerevisiae suspension was evaluated to determine cell immobilization rates. Once immobilization was established, biodegradation assays with free and immobilized yeast in PEI-treated sugarcane bagasse were evaluated for 240 h using UV–vis spectrophotometry. The analysis revealed significant relative absorbance values, indicating the occurrence of biodegradation in both treatments. Therefore, S. cerevisiae immobilized in sugarcane bagasse is very attractive for use in biodegradation processes for the treatment of textile effluents.     

Plant- and microbe-assisted biochar amendment technology for petroleum hydrocarbon remediation in saline-sodic soils: A review

Soil degradation through salinization and pollution by toxic compounds such as petroleum hydrocarbons(PHCs) in the coastal wetlands has become a significant threat to ecosystem health, biodiversity, and food security. However, traditional remediation technologies can generate secondary pollutants, incur high operating costs, and consume significant quantities of energy. Bioremediation, using plants, biochar, and microbes, is an innovative and cost-effective option to remediate contaminated soils. Biochar, as a plant/microbe growth enhancer, is a promising green approach for the sustainable phytoremediation of PHCs in salinized soils. This review therefore summarizes the effect of plant-and microbe-assisted biochar amendment technology for the remediation of PHCs and salinization. Plant-microbe interactions mediated rhizodegradation despite increasing hydrocarbon sorption. Overall, microbial respiration is more active in biochar amendments, due to faster biodegradation of PHCs and improved soil properties. The use of biochar, plants, and microbes is recommended,as it offers a practical and sustainable option, both ecologically and economically, for the remediation of PHCs and excess salinity. Further development of new green technologies is to be encouraged.     

土地利用变化对闽江河口湿地表层土壤有机碳含量及其活性的影响

对闽江河口原生植被芦苇沼泽,以及由其转化的不同其它土地利用类型(滩涂养殖地、水田、草地、撂荒地和池塘养殖地)的表层(0-50 cm)沉积物(或土壤)有机碳和活性有机碳含量的研究,结果表明,滩涂养殖地、水田、池塘养殖地、草地和撂荒地的土壤有机碳含量分别比芦苇沼泽地低27%,75%,67%,1%,60%;在有机碳储量方面,滩涂养殖地、水田、池塘养殖地和撂荒地比天然芦苇沼泽地分别低11%,50%,37%,24%,草地有机碳储量比芦苇高44%;草地土壤有机碳含量和储量随土层加深而递减的幅度比芦苇地大;水田有机碳含量和储量垂直变化不明显,弃耕后,表层有机碳含量提高,垂直变化明显。不同土地利用方式间土壤活性有机碳含量的差异比有机碳的差异大,与芦苇地相比,滩涂养殖地、水田、池塘、草地活性有机碳含量分别低24%,83%,84%,42%;撂荒10年的弃耕地与水稻田土壤相比,活性有机碳含量提高了47%。     

Behaviour and assessment of bioavailability of organic contaminants in soil: relevance for risk assessment and remediation

Abstract. Soils contaminated with organic chemicals are now widespread in industrialized and developing countries, and the risk assessment and remediation of such contaminated sites is a priority. However, containment and remediation strategies are complicated in many cases by the range of contaminants present and the historical nature of the contamination. Research has increased our understanding of the behaviour of organic contaminants in soil and the factors that control their behaviour. There is a fundamental need to understand and, where possible, quantify the bioavailable fraction as well as the total concentration of contaminant present in soil: the bioavailable fraction is key to toxicity or biodegradation. To quantify these fractions, a large number of techniques have been employed, ranging from organic and aqueous based solvent extractions to the use of biota. Many studies have been carried out investigating the use of chemical techniques to describe bioavailability, which could be used in the assessment and remediation of contaminated land. The aim of this review is to consider the behaviour of organic contaminants in soil, highlighting issues of bioavailability, and then to discuss the relevance of the various methods for assessing risk and potential remediation of organic contaminants in soil.     

Removal of Zinc from Tidal Water by Sediments of a Mangrove Ecosystem: A Radiotracer Study

The removal of ⁶⁵Zn from tidal water by underlaying sediment cores collected in a mangrove forest and a tidal creek that drains this forest in Sepetiba Bay (SE Brazil) was investigated. After 30-h experiments in laboratory microcosms, the ⁶⁵Zn half-removal times from tidal creek and mangrove forest sediments were 8.7?±?1.8 and 9.2?±?0.9 h respectively. Depth penetration of ⁶⁵Zn was mainly restricted to the upper 3 cm in mangrove forest cores, while detectable ⁶⁵Zn activities were found in all layers (0–7 cm depth) of tidal creek cores. An unexpected ⁶⁵Zn release back to the overlaying water was observed for one of the tidal creek experiments in the 12–18 h interval (corresponding to a return of 17% of the initial ⁶⁵Zn activity in overlaying water), suggesting a reversibility of the ⁶⁵Zn removal process (e.g., by adsorption) in tidal creek sediments. The results indicate that mangrove-vegetated sediments allowed a lower vertical mobility of Zn than observed in creek sediments and mangrove sediments appear to be less susceptible to a reversion in the process of zinc removal from overlaying water, suggesting a greater capacity to retain this metal near the water–sediment interface. This first radiotracer approach on the mangrove sediments removal of Zn from tidal waters supports earlier experimental studies employing stable Zn, contributing for a better understanding of the metal uptake kinetics by such sediments and suggesting that these sediments act as active sinks for trace metals.     

Waterjet injection of powdered activated carbon for sediment remediation

Purpose  

In situ contaminated sediment remediation through the addition of activated carbon has been proven to be an effective remediation technique. An amendment delivery system was developed to accurately place and inject a powdered activated carbon slurry. The system was set up to deliver a series of discrete injections over a rectangular grid with the objective to deliver 3% carbon (C) by dry weight to an inundated saturated sediment at a maximum sediment depth of 30 cm.     

Preliminary Assessment of Oil Contamination Levels in Soils Contaminated with Oil Lakes in the Greater Burgan Oil Fields,Kuwait

Measurements taken for total petroleum hydrocarbons (TPHs), total organic carbon (TOC) and trace metals [vanadium (V), nickel (Ni), cadmium (Cd) and lead (Pb)] in 40 soil samples are used to delineate oil contamination levels and state of oil penetration in soils heavily contaminated with oil lakes in Al-Ahmadi and Burgan oil fields. All soil horizons in Al-Ahmadi profile contain very high concentrations of TPHs down to the depth interval 80–95 cm. In contrast, TPH contaminations are restricted to the upper 50 cm layer in the Burgan profiles, then drop sharply to natural background levels in subsequent soil horizons. A strong and positive relationship exists between the high TOC and TPH contents of the two profiles. The two soil profiles contain contaminations of V and Ni as well as high concentrations of Cd and Pb. Possible sources of these metals are oil contaminants from the lakes and/or deposited airborne oil fallouts. V/Ni ratios of the surface tar sludge and the soil horizons in the two profiles cannot be used in identifying terrestrial oil spills or as indicators of oil contamination in Kuwaiti soils.     

初始含水率对土壤中原油入渗的影响

为确定土壤初始含水率对原油在土壤中入渗的影响,该文利用3种土壤,根据设定不同初始含水率进行配置,开展土柱模拟试验,研究了不同初始含水率条件下原油在土壤中的入渗。试验结果表明：对于同一质地土壤,随着初始含水率的增加,原油在土壤中入渗的湿润距离和湿润推进速率均增加。原油在土壤中的入渗与土壤粉粒含量密切相关,当土壤初始含水率较低时,不同质地土壤,粉粒含量越高,原油在土壤中入渗越慢;随土壤深度增加,土壤中原油残留物的含量呈波动递减趋势;原油在土壤中入渗的湿润距离随时间的变化可用对数函数拟合,湿润推进速率与时间的关系可用Kostiakov公式拟合。     

中国长江口潮滩湿地土壤重金属含量的时空变化规律及环境指示意义

The environment of estuarine wetlands has been attracting worldwide attention. To study the spatial distribution of pollutants in the tidal flats of the Yangtze Estuary, Southeast China, the Eastern Tidal Flat of Chongming Island (EC) and the Jiuduansha Shoal (JS) of the estuary were selected as the study sites. At each of the two sites, a cross-transect from land to sea was established and topsoil and soil core samples in the cross-transect were collected spatially and seasonally to determine their contents of heavy metals (Cu, Zn, Pb, Cd, Cr, Ni, Mn, and Fe) and grain-size characteristics. The results showed that the heavy metal loads were commonly higher in the soils of nearshore high tidal flats and had a tendency of decreasing from land to sea at both of the study sites. The contents of heavy metals in the soils of the high and medial tidal flats were mostly higher in April and November but lower in July. Corresponding spatial and seasonal variations in grain size of the intertidal soils were also observed at the two study sites. The soils in the nearshore high tidal flats were finer and gradually got coarser seawards; they were relatively finer in April and November but coarser in July. Furthermore, the contents of heavy metals in the intertidal soils of both the sites EC and JS were significantly positively correlated with the clay (<2 μm) and 2-20 μm fractions, but negatively with the sand (>63 μm) and 20-63 μm fractions, which suggested that the heavy metals in the intertidal soils were primarily combined with the fine particulate fraction (<20 μm), especially clay, and hence the spatial and seasonal variations in heavy metals were actually caused by the change of the grain-size characteristics of the intertidal soils due to the different sedimentary environments in the estuary. The results of this study may also contribute to a better understanding of the soil formation and classification in the tidal flats of the Yangtze Estuary.     

Physical Properties as Indicators of Oil Penetration in Soils Contaminated with oil Lakes in the Greater Burgan Oil Fields,Kuwait

Measurements were made on 60 samples to determine the physical properties of the soil profiles contaminated with oil lakes in Al-Ahmadi and Burgan oil fields which include 80% of the Greater Burgan oil wells in southern Kuwait. The two soil profiles have similar saturation percentages, field capacities, wilting coefficients, low available water capacities due to statification and very low matric potential, and high bulk densities due to compaction by vehicle wheels. The fluviatile origin, relatively poor sorting and unstable structure of the Burgan soil layers have led to lower hydraulic conductivity and permeability, thereby restricting oil penetration mainly to the upper 25–45 cm layer. In contrast, the eolian origin, excellent sorting and stable structure of Al-Ahmadi soil layers have resulted in higher hydraulic conductivity and permeability, and hence allowed the spreading of oil over much greater depths (down to 150 cm). The very low values of the hydraulic conductivities and available water capacities of the zone(s) lying below the impervious Gatch (caliche) layer in the two soil profiles suggest that this layer could act as a moisture barrier impeding any further downward oil penetration.     

三种植被类型植物根系对崇明岛海岸带稳定性的影响

Coastal erosion is currently a major problem along the southern coast of Chongming Island, Shanghai. To enhance the erosion protection ability of coastal shelterbelts, two woody tree species, Taxodium ascendens and Salix babylonica, were planted separately into Phragmites australis + Scirpus mariqueter communities in 2006. Two years later, we investigated whether either of these experiments reduced erosion and increased stability in the native herbaceous plant community. We also examined soil stability and root length density under T. ascendens added, S. babylonica added and native herbaceous vegetation conditions along an intertidal gradient from the soil surface to a depth of 40 cm in each experiment, thus to determine the capacity of T. ascendens and S. babylonica to contribute to shoreline stabilization. Topsoil under the native vegetation had greater stability at the middle and higher intertidal zones because its soil stability index and root length density were significantly higher than in the T. ascendens or S. babylonica planted communities. The effect of T. ascendens on soil stability was not generally better than that of the native vegetation. Only at the 20-30 cm soil depth of the middle intertidal zone and in the 10-20 cm layer of the higher intertidal zone the soil stability index and root length densities under the T. ascendens added condition were significantly higher (P < 0.05) than those of the native vegetation. The S. babylonica planted soil had greater stability in the deeper soil layer than the soil under either the native vegetation or the T. ascendens added condition, and its soil stability index and root length density were significant higher (P < 0.05) than those of other vegetation conditions at the 30-40 cm soil depth for the lower intertidal zone and at the 20-40 cm layer for middle and higher intertidal zones.     

Influence of Water Content and Plants on the Dissipation of Chlorinated Volatile Organic Compounds in Soil

To devise effective procedures for the remediation of soil contaminated by VOCs, an improved understanding of their fate and transport mechanisms in soil is essential. To show the effect of plants on the dissipation of 1,1,1-trichloroethane (TCA), trichloroethylene (TCE) and tetrachloroethylene (PCE), two types of experiments, vial and column, were conducted. The results suggested that keeping the soil moisture content at field capacity is desirable for VOCs dissipation. All VOCs were dissipated quickly in unplanted columns than planted conditions in early periods of the experiment because more volatilization occurred in unplanted conditions. The plants could take up and retard volatile contaminants, and prevent contamination of ambient air. Although the time for acclimation for microbial communities to contaminants for enhanced biodegradation should be considered, phytoremediation is potentially a cost-effective remediation technique for soils contaminated by volatile organic compounds (VOCs).     

微生物法修复陕北油田污染土壤的研究现状与展望

较全面地介绍了油田污染土壤的微生物修复技术,并结合国内外在该领域的研究成果,论述了当今微生物修复陕北油田区污染土壤的研究现状。并针对现有研究中存在的不足,总结了今后研究的趋势与重点。     

利用表面活性剂强化去除土壤中NAPLs的研究进展

该文评述了近年来国内外利用表面活性剂去除土-水系统中非水相流体(NAPLs)的研究进展,重点讨论了其作用机理和主要影响因素。大量研究表明,表面活性剂能促进NAPLs从土壤颗粒中解吸,并通过增溶和增流作用改善NAPLs在土壤中的溶解和迁移能力,进而提高抽出处理法的去除效率。同时,表面活性剂对NAPLs的生物降解也有一定影响。表面活性剂对NAPLs去除效率与其种类和投加浓度、土壤异质性、电解质和温度等因素有关。     

Quantification of the vertical translocation rate of soil solid-phase material by the magnetic tracer method

Approaches to the quantification of the vertical translocation rate of soil solid-phase material by the magnetic tracer method have been developed; the tracer penetration depth and rate have been determined, as well as the radial distribution of the tracer in chernozems (Chernozems) and dark gray forest soils (Luvisols) of Belgorod oblast under natural steppe and forest vegetation and in arable lands under agricultural use of different durations. It has been found that the penetration depth of spherical magnetic particles (SMPs) during their 150-year-occurrence in soils of a forest plot is 68 cm under forest, 58 cm on a 100-year old plowland, and only 49 cm on a 150-year-old plowland. In the chernozems of the steppe plot, the penetration depth of SMPs exceeds the studied depth of 70 cm both under natural vegetation and on the plowlands. The penetration rates of SMPs deep into the soil vary significantly among the key plots: 0.92–1.32 mm/year on the forest plot and 1.47–1.63 mm/year on the steppe plot, probably because of the more active recent turbation activity of soil animals.     

重金属污染土壤的螯合剂诱导植物修复研究进展

植物修复作为一种生态友好型原位绿色修复技术成为重金属污染土壤修复研究的热点。然而,目前最具有推广价值的超积累植物因生物量低、生长缓慢、对重金属的积累具有专一性等缺点,大大限制了植物修复技术在重金属污染尤其是复合重金属污染土壤治理方面的推广应用。利用生长速度快、生物量大的普通植物借助其它技术辅助的联合植物修复便成了有效可行的替代途径和研究焦点。近年来,金属螯合剂诱导的化学-植物联合修复技术备受关注。本文综述了螯合剂诱导植物修复技术的研究进展、修复机理和目前存在的问题,并对该项技术的未来研究方向给予了展望。     

土壤中氯苯类化合物的归趋过程及潜在修复策略研究进展

Chlorobenzenes (CBs) are a group of organic pollutants that pose a high environmental risk due to their toxicity,persistence and possible transfer in the food chain.Available data in literature show that CBs are detected in different environmental compartments such as soil,water,air and sediment.The widespread presence of CBs in the environment is related to their former extensive use in agriculture and industry.Some CBs are ranked in the list of priority pollutants by the Stockholm Convention,and their reduction or elimination from the environment is therefore of high importance.Environmental risk assessment of CBs requires knowledge on the role and importance of the main environmental fate processes,especially in soil.Furthermore,development of remediation strategies for reduction or elimination of CBs from the environment is related to the enhancement of fate processes that increase their dissipation in various environmental compartments.The main objectives of the current review were to present up-to-date data on fate processes of CBs in the soil environment and to explore possible remediation strategies for soils contaminated with CBs.Dechlorination of highly-chlorinated benzenes is the main degradation pathway under anaerobic conditions,leading to the formation of lower-chlorinated benzenes.Biodegradation of lower-chlorinated benzenes is well documented,especially by strains of adapted or specialized microorganisms.Development of techniques that combine dechlorination of highly-chlorinated benzenes with biodegradation or biomineralization of lower-chlorinated benzenes can result in useful tools for remediation of soils contaminated with CBs.In addition,immobilization of CBs in soil by use of different amendments is a useful method for reducing the environmental risk of CBs.