Coupled abiotic-biotic mineralization of 2,4,6-trinitrotoluene (TNT)

Munitions wastes such as TNT are widespread contaminants in soils and ground waters. We investigated a coupled abiotic-biotic treatment scheme for remediation of aqueous solutions of TNT. Mineralization of aqueous TNT (0.22 mM) was initially optimized with minimum reactant use (Fe3+ and H2O2) in light-assisted and dark, modified Fenton reactions at acidic and neutral pH. Complete TNT degradation occurred under all reaction conditions within 24 h. Using the optimum reactant concentrations, coupled abiotic-biotic reactions showed an increase in TNT mineralization, from 47 to 80%, after biomass addition to the acidic, dark Fenton-like reaction. Comparable increases of TNT mineralization were observed under neutral pH with similar reaction conditions. In light-assisted Fenton-like reactions at neutral pH, no increase in cumulative TNT mineralization (66%) was seen in coupled abiotic-biotic reactions. Abiotic photo-Fenton-like reactions alone, at acidic pH, produced complete TNT mineralization and required no biotic assistance. While light-enhanced Fenton reactions alone can provide high levels of TNT mineralization, the dark abiotic-biotic reaction scheme has perhaps a wider use due to a similar extent of TNT mineralization in the absence of light, leading to possible applications in soil slurry and in situ processes in the subsurface.     

Remediation of oil spills in temperate and tropical coastal marine environments

Oil is the world’s primary source of non-renewable energy, and it has also contaminated ocean coastlines due to spills. It is therefore important to have remediation treatments that are both effective, and ecologically not harmful. Current in situ bioremediation methods consist primarily of biostimulation, through addition of nutrients, and bioaugmentation, the addition of hydrocarbon degrading microorganisms. The purpose of this article is to discuss successful and unsuccessful remediation through the use of biostimulation, bioaugmentation, or a combination of both. As microbial treatments are capable of enhancing coastal oil remediation in temperate and tropical settings, the success of a particular remediation approach will be determined based on the type and amount of oil, type of soil and/or sediment, microbial inoculants and the often changing physical, chemical and biological environmental conditions. Environmental factors and limitations will be discussed as to why certain bioremediation events were successful while others were not.     

石油污染土壤微生物联合修复技术研究进展

石油是一种具有生物毒性的复杂有机物,土壤中石油烃的过量积累会给生态环境和人类健康造成严重威胁。微生物联合修复技术因处理成本低、环境影响小、无二次污染等优点,且较微生物修复或植物修复效率更高,耗时更短,成为当前的研究热点。文章介绍了植物-微生物联合修复、电动-微生物联合修复、氧化-微生物联合修复和表面活性剂强化微生物修复四种联合修复技术,简要阐述了修复机理、适用范围和工艺参数,为生物修复技术的选择提供了参考,并对以后生物修复的研究重点进行了展望。     

Kinetic effect of humic acid on alachlor degradation by anodic Fenton treatment

Contamination of water often results from the heavy use of agricultural chemicals, and the disposal of aqueous pesticide waste is a concern. Anodic Fenton treatment (AFT) has been shown to be a successful remediation method for pesticides in solution, but the effect of soil on the degradation kinetics of pesticides using this method has not been determined. The purpose of this study was to study the effect of humic acid, as a soil surrogate, on the degradation kinetics of alachlor [2-chloro-N-(2,6-diethylphenyl-N-(methoxymethyl) acetamide], a heavily used herbicide that has been studied in pure aqueous solution by AFT. The AFT consists of a controlled constant delivery of Fenton reagents, using an electrochemical half-cell to deliver ferrous iron. Alachlor was quickly degraded by AFT, and the kinetics were found to obey the previously developed AFT model well. Degradation of alachlor by AFT in humic acid slurry showed that when the amount of humic acid was increased, alachlor degradation was significantly slowed down and the degradation kinetics were shifted from the AFT model to a first-order model. Further experimentation indicated that humic acid not only competes with alachlor for hydroxyl radicals, reducing the degradation rate of the target compound, but also buffers the slurry at near neutral pH, blocking regeneration of ferrous ion from ferric ion and subsequently shifting the kinetics to first order. Degradation of several other pesticides in humic acid slurry also followed first-order kinetics. These results imply that higher concentrations of Fenton reagents will be required for soil remediation.     

Designing sustainable and economically attractive brownfield revitalization options using an integrated assessment model

We describe the development of an integrated assessment model which evaluates redevelopment options of large contaminated brownfields and we present the application of the model in a case study. Aiming to support efficient and sustainable revitalization and communication between stakeholders, the presented assessment model integrates three pinnacles of brownfield revitalization: (i) subsurface remediation and site preparation costs, (ii) market-oriented economic appraisal, and (iii) the expected contribution of planned future land use to sustainable community and regional development. For the assessment, focus is set on the early stage of the brownfield redevelopment process, which is characterized by limited data availability and by flexibility in land use planning and development scope. At this stage, revealing the consequences of adjustments and alterations in planning options can foster efficiency in communication between the involved parties and thereby facilitates the brownfield revitalization process. Results from the case-study application indicate that the integrated assessment provides help in the identification of land use options beneficial in both a sustainable and an economical sense. For the study site it is shown on one hand that brownfield redevelopment is not automatically in line with sustainable regional development, and on the other hand it is demonstrated that additional contributions to sustainability are not intrinsically tied to increased costs.     

Effect of bioremediation on the growth of Okro (<Emphasis Type="Italic">Abelmoshus esculetus</Emphasis>) in the Niger Delta soils

This paper communicates the effect of bioremediation on the performance of Okro plant (Abelmoshus esculentus) in a typical Niger Delta soil that has received 5% crude oil pollution level. Biodegrading bacteria such as Pseudomonas fluorescen, Acinetobacteria iwofii, Bacillus subtilus, Arthrobacter globiformis that was isolated from previously polluted soils was introduced into the samples. The treatment combinations are as follows (A) = control without crude oil; B = soil + crude oil, (C) = soil + crude oil + microbes, (D) = soil + crude oil + microbes, (E) = soil + crude oil + microbes + fertilizer (F) soil + microbes and (G) = soil + fertilizer. The treatment (E) gave the highest number of leaves, % crop emergence, plant biomass, microbial population and degradation of petroleum hydrocarbon compared to any of the treatments that had received crude oil. This suggested that fertilizer application does not only stimulate microbial growth but it provides the plant with more available nutrients required for plant growth.     

Fate of arsenic in swine waste from concentrated animal feeding operations

Swine diets are often supplemented by organoarsenicals, such as 3-nitro-4-hydroxyphenylarsonic acid (roxarsone) to treat animal diseases and promote growth. Recent work reported roxarsone degradation under anaerobic conditions in poultry litter, but no such data exist for swine wastes typically stored in lagoons nearby concentrated animal feeding operations (CAFOs). The objectives of this study were to: (i) characterize a suite of swine wastes collected from 19 randomly selected CAFOs for soluble arsenate [As(V)], arsenite [As(III)], dimethylarsenic acid (DMA), monomethylarsonic acid (MMA), 3-amino-4-hydroxyphenylarsonic acid (3-HPPA), p-arsanilic acid, and roxarsone, and (ii) determine the geochemical fate of roxarsone in storage lagoons nearby CAFOs. Swine waste suspensions were spiked with roxarsone and incubated under dark/light and aerobic/anaerobic conditions to monitor roxarsone degradation kinetics. Arsenic speciation analysis using liquid chromatography and inductively coupled plasma mass spectrometry (LC-ICPMS) illustrated the prevalence of As(V) in swine waste suspensions. Roxarsone underwent degradation to either organoarsenicals (3-HPPA) or As(V) and a number of unidentified metabolites. Roxarsone degradation occurred under anaerobic conditions for suspensions low in solids content, but suspensions higher in solids content facilitated roxarsone degradation under both anaerobic and aerobic conditions. Increased solids content enhanced roxarsone degradation kinetics under aerobic conditions. According to current waste storage and sampling practices, arsenic in swine wastes stored in lagoons has been overlooked as a possible environmental health issue.     

Stimulated rhizodegradation of atrazine by selected plant species

The efficacy of vegetative buffer strips (VBS) in removing herbicides deposited from surface runoff is related to the ability of plant species to promote rapid herbicide degradation. A growth chamber study was conducted to compare C-atrazine (ATR) degradation profiles in soil rhizospheres from different forage grasses and correlate ATR degradation rates and profiles with microbial activity using three soil enzymes. The plant treatments included: (i) orchardgrass ( L.), (ii) smooth bromegrass ( Leyss.), (iii) tall fescue ( Schreb.), (iv) Illinois bundle flower (), (v) perennial ryegrass ( L.), (vi) switchgrass ( L.), and (vii) eastern gamagrass (). Soil without plants was used as the control. The results suggested that all plant species significantly enhanced ATR degradation by 84 to 260% compared with the control, but eastern gamagrass showed the highest capability for promoting biodegradation of ATR in the rhizosphere. More than 90% of ATR was degraded in the eastern gamagrass rhizosphere compared with 24% in the control. Dealkylation of atrazine strongly correlated with increased enzymatic activities of β-glucosidase (GLU) ( = 0.96), dehydrogenase (DHG) ( = 0.842), and fluorescein diacetate (FDA) hydrolysis ( = 0.702). The incorporation of forage species, particularly eastern gamagrass, into VBS designs will significantly promote the degradation of ATR transported into the VBS by surface runoff. Microbial parameters widely used for assessment of soil quality, e.g., DHG and GLU activities, are promising tools for evaluating the overall degradation potential of various vegetative buffer designs for ATR remediation.     

三氯乙烯污染地下水的原位修复技术研究及应用现状

三氯乙烯(TCE)在工业生产中的大规模使用,使其成为土壤和地下水中分布最广泛的污染物之一。本文综述了TCE污染地下水的原位修复方法,包括化学氧化法、电动修复法、生物修复以及渗透反应格栅技术,文章并对今后研究发展趋势进行了讨论。     

Biogas production from slaughterhouse wastewaters and use of biofertilizer obtained for biodegradation of aromatic hydrocarbons

The anaerobic digestion of industrial wastes produces a biogas that is an alternative to the use of fossil fuels for energy production. At the end of this process, the stabilized biomass presents high levels of nutrients, which can be used both as biofertilizers in agriculture and for the biodegradation of contaminants in the soil through improvement of the microbiota. Thus, this study aimed to evaluate biogas production by industrial wastes and to use the biofertilizer for the bioremediation of soils previously contaminated with gasoline. The biomass (420 mL) generated approximately 10 liters (L) of methane and 3 L of other gases. Anaerobic incubation reduced total and volatile solids, as well as biochemical oxygen demand, chemical oxygen demand, and the carbon and nitrogen contents of the biomass. The bioremediation experiment showed that 15 days after contamination with gasoline, the addition of the biofertilizer improved the degradation efficiency of monoaromatic hydrocarbons; however, the degradation of polyaromatic hydrocarbons was less time efficient. So, we conclude that the anaerobic incubation of industrial wastes generates a high amount of biogas, and that biofertilizer deposition into contaminated soil does not affect the efficiency of the degradation of aromatic hydrocarbons after 30 days. Novelty or significance : Anaerobic incubation of industrial wastes generates a high calorific value gas, which can be used as an alternative source of energy. And, the resulting biomass, called biofertilizer, can be used to remediate soils contaminated with hydrocarbons.     

Bioremediation of soils contaminated with explosives

The large-scale industrial production and processing of munitions such as 2,4,6-trinitrotoluene (TNT) over the past 100 years led to the disposal of wastes containing explosives and nitrated organic by-products into the environment. In the US, the Army alone has estimated that over 1.2 million tons of soil have been contaminated with explosives, and the impact of explosives contamination in other countries is of similar magnitude. In recent years, growing concern about the health and ecological threats posed by man-made chemicals have led to studies of the toxicology of explosives, which have identified toxic and mutagenic effects of the common military explosives and their transformation products (Bruns-Nagel et al., 1999a; Fuchs et al., 2001; Homma-Takeda et al., 2002; Honeycutt et al., 1996; Rosenblatt et al., 1991; Spanggord et al., 1982; Tan et al., 1992 and Won et al., 1976). Because the cleanup of areas contaminated by explosives is now mandated because of public health concerns, considerable effort has been invested in finding economical remediation technologies. Biological treatment processes are often considered, since these are usually the least expensive means of destroying organic pollution. This review examines the most important groups of chemicals that must be treated at sites contaminated by explosives processing, the chemical and biological transformations they undergo, and commercial processes developed to exploit these transformations for treatment of contaminated soil. We critically examine about 150 papers on the topic, including approximately 60 published within the past 5 years.     

石油污染土壤生物修复技术的研究进展

本文综述了30多年来国内外石油污染土壤的生物修复的进展,并介绍了国内外在修复石油污染土壤方面的生物修复工艺：原位生物修复和异位生物修复。原位修复有原位地耕法和土壤气相抽提;异位修复有土壤耕作发、堆放法、堆肥法和反应器法。文章还就今后的研究方向作了阐述,指出生物修复方法作为一种费用低、效果好、对环境影响低、无二次污染的方法,是今后治理石油对土壤污染的最可行的方法。     

The double-edged sword of grant funding: a study of community-led climate change initiatives in remote rural Scotland

Community-led initiatives are commonly advocated as an effective way of encouraging individuals to adopt more sustainable lifestyles. Since 2008, the Scottish Government's climate challenge fund (CCF) has distributed over £50 million in grants to community-led, carbon-saving projects across the country. Drawing on participant observation within two CCF organisations in remote rural Scotland, this paper examines the assumption that the receipt of government funding is necessarily of overall benefit to community-led initiatives attempting to facilitate more sustainable communities in the long term. Observations indicate that funding can bring with it a number of significant complications to community-scale action as a result of: (i) misaligned output timeframes, (ii) administration demands, and (iii) local competition. It is concluded that the design of funding schemes can in fact hamper the full potential of grassroots initiatives to engender more sustainable lifestyles throughout the community.     

Economics of salt‐induced land degradation and restoration

Food security concerns and the scarcity of new productive land have put productivity enhancement of degraded lands back on the political agenda. In such a context, salt‐affected lands are a valuable resource that cannot be neglected nor easily abandoned even with their lower crop yields, especially in areas where significant investments have already been made in irrigation and drainage infrastructure. A review of previous studies shows a very limited number of highly variable estimates of the costs of salt‐induced land degradation combined with methodological and contextual differences. Simple extrapolation suggests that the global annual cost of salt‐induced land degradation in irrigated areas could be US$ 27.3 billion because of lost crop production. We present selected case studies that highlight the potential for economic and environmental benefits of taking action to remediate salt‐affected lands. The findings indicate that it can be cost‐effective to invest in sustainable land management in countries confronting salt‐induced land degradation. Such investments in effective remediation of salt‐affected lands should form part of a broader strategy for food security and be defined in national action plans. This broader strategy is required to ensure the identification and effective removal of barriers to the adoption of sustainable land management, such as perverse subsidies. Whereas reversing salt‐induced land degradation would require several years, interim salinity management strategies could provide a pathway for effective remediation and further showcase the importance of reversing land degradation and the rewards of investing in sustainable land management.     

Sorption and degradation of pesticides in nursery recycling ponds

Knowledge of pesticide distribution and persistence in nursery recycling pond water and sediment is critical for preventing phytotoxicity of pesticides during water reuse and to assess their impacts to the environment. In this study, sorption and degradation of four commonly used pesticides (diazinon, chlorpyrifos, chlorothalonil, and pendimethalin) in sediments from two nursery recycling ponds was investigated. Results showed that diazinon and chlorothalonil were moderately sorbed [K(OC) (soil organic carbon distribution coefficient) from 732 to 2.45 x 10(3) mL g(-1)] to the sediments, and their sorption was mainly attributable to organic matter content, whereas chlorpyrifos and pendimethalin were strongly sorbed (K(OC) > or = 7.43 x 10(3) mL g(-1)) to the sediments, and their sorption was related to both organic matter content and sediment texture. The persistence of diazinon and chlorpyrifos was moderate under aerobic conditions (half-lives = 8 to 32 d), and increased under anaerobic conditions (half-lives = 12 to 53 d). In contrast, chlorothalonil and pendimethalin were quickly degraded under aerobic conditions with half-lives < 2.8 d, and their degradation was further enhanced under anaerobic conditions (half-lives < 1.9 d). The strong sorption of chlorpyrifos and pendimethalin by the sediments suggests that the practice of recycling nursery runoff would effectively retain these compounds in the recycling pond, minimizing their offsite movement. The prolonged persistence of diazinon and chlorpyrifos, however, implies that incidental spills, such as overflows caused by storm events, may contribute significant loads of such pesticides into downstream surface water bodies.     

HPLC-MSn to investigate the oxidative destruction pathway of aromatic sulfonate wastes

The article concerns the problem of destruction and remediation of industrial wastes containing aromatic sulfonates. The effects of an oxidation process induced by thermally activated persulfate in the degradation of 1,5-naphthalenedisulfonate (NDS) are investigated by the use of UV-Vis spectrophotometry, high performance liquid chromatography-mass spectrometry (HPLC-MS) and HPLC-MS(n) techniques. The results obtained indicated that thermal activation (80 degrees C) of a solution containing NDS and sodium persulfate in a molar ratio equal to 1 leads to the cleavage of the naphthalene structure. Estimated chemical oxygen demand (COD) indicates that when the excess of persulfate is equal to 100, NDS undergoes a mineralization of the order of 90%. A degradation pathway undergone by NDS when thermally activated in the presence of persulfate is proposed.     

土壤中砷的污染控制技术研究

土壤砷污染修复是世界性的难题,日益受到人们的密切关注。本文阐述了土壤砷污染的现状、危害及其来源,探讨土壤砷污染的传统物理化学和生物修复技术的研究现状及特点的同时,重点阐述了纳米材料修复技术,尤其是纳米铁技术,并对土壤砷污染修复研究方向进行了展望。     

Mapping socio-economic scenarios of land cover change: a GIS method to enable ecosystem service modelling

We present a GIS method to interpret qualitatively expressed socio-economic scenarios in quantitative map-based terms. (i) We built scenarios using local stakeholders and experts to define how major land cover classes may change under different sets of drivers; (ii) we formalized these as spatially explicit rules, for example agriculture can only occur on certain soil types; (iii) we created a future land cover map which can then be used to model ecosystem services. We illustrate this for carbon storage in the Eastern Arc Mountains of Tanzania using two scenarios: the first based on sustainable development, the second based on 'business as usual' with continued forest-woodland degradation and poor protection of existing forest reserves. Between 2000 and 2025 4% of carbon stocks were lost under the first scenario compared to a loss of 41% of carbon stocks under the second scenario. Quantifying the impacts of differing future scenarios using the method we document here will be important if payments for ecosystem services are to be used to change policy in order to maintain critical ecosystem services.     

Field-scale variation in microbial activity and soil properties in relation to mineralization and sorption of pesticides in a sandy soil

Pesticides applied to agricultural soils are subject to environmental concerns because leaching to groundwater reservoirs and aquatic habitats may occur. Knowledge of field variation of pesticide-related parameters is required to evaluate the vulnerability of pesticide leaching. The mineralization and sorption of the pesticides glyphosate and metribuzin and the pesticide degradation product triazinamin in a field were measured and compared with the field-scale variation of geochemical and microbiological parameters. We focused on the soil parameters clay and organic carbon (C) content and on soil respiratory and enzymatic processes and microbial biomass. These parameters were measured in soil samples taken at two depths (Ap and Bs horizon) in 51 sampling points from a 4-ha agricultural fine sandy soil field. The results indicated that the spatial variation of the soil parameters, and in particular the content of organic C, had a major influence on the variability of the microbial parameters and on sorption and pesticide mineralization in the soil. For glyphosate, with a co-metabolic pathway for degradation, the mineralization was increased in soils with high microbial activity. The spatial variability, expressed as the CV, was about five times higher in the Bs horizon than in the Ap horizon, and the local-scale variation within 100 m(2) areas were two to three times lower than the field-scale variation within the entire field of about 4 ha.     

Potential mineralization of four herbicides in a ground water--fed wetland area

Herbicides may leach from agricultural fields into ground water feeding adjacent wetlands. However, only little is known of the fate of herbicides in wetland areas. The purpose of the study was to examine the potential of a riparian fen to mineralize herbides that could leach from an adjacent catchment area. Slurries were prepared from sediment and ground water collected from different parts of a wetland representing different redox conditions. The slurries were amended with O2, NO3-, SO4(2-), and CO2, or CO2 alone as electron acceptors to simulate the in situ conditions and their ability to mineralize the herbides mecoprop, metsulfuron-methyl, isoproturon and atrazine. In addition, the abundance of bacteria able to utilize O2, NO3-, SO4(2-) + CO2, and CO2 as electron acceptors was investigated along with the O2-reducing and methanogenic potential of the sediment. The recalcitrance to bacterial degradation depended on both the type of herbicide and the redox conditions pertaining. Mecoprop was the most readily degraded herbicide, with 36% of [ring-U-14C]mecoprop being mineralized to 14CO2 under aerobic conditions after 473 d. In comparison, approximately 29% of [phenyl-U-14C]metsulfuron-methyl and 16% of [ring-U-14C]isoproturon mineralized in aerobic slurries during the same period. Surprisingly, 8 to 13% of mecoprop also mineralized under anaerobic conditions. Neither metsulfuron-methyl nor isoproturon were mineralized under anaerobic conditions and atrazine was not mineralized under any of the redox conditions examined. The present study is the first to report mineralization of meco-prop in ground water in a wetland area, and the first to report mineralization of a phenoxyalcanoic acid herbicide under both aerobic and anaerobic conditions.