包气带中氯代烃运移特性及原位生物修复研究进展

Migration behavior and in-situ bioremediation of chlorinated hydrocarbon solvent in vadose zone: a review

氯代烃(chlorinated hydrocarbon solvent,CHS)污染广泛存在于土壤包气带中,明晰CHS在包气带中的运移特性及生物降解规律对原位生物修复有重要意义.首先对CHS在包气带中的相态分布、不同相态间相互作用关系及运移特性进行系统总结,CHS在包气带中存在NAPL、溶解相、吸附相、气相和其他相态等多种相态,其在包气带中存在早期、中期和后期3个衰减演变阶段,相态变化及扩散矩阵大小是不同阶段的重要指示指标;同时,气、固、液及NAPL相态CHS在包气带中存在多种相互作用关系.随后概述CHS在包气带中好氧共代谢、直接氧化和厌氧还原脱氯3种主要生物代谢途径特征及其影响因素,一般而言厌氧脱氯能力随氯原子个数减小而降低,好氧降解能力随氯原子个数减小而增大.然后总结当前包气带中基于生物刺激和生物强化手段原位修复CHS研究现状,表明添加营养物质和注入厌氧脱氯菌株产乙烯脱卤拟球菌Dehalococcoides是有效的修复手段.同时,对包气带中CHS生物降解的影响因素进行概述,明晰调控氧化还原特性(氧气)对CHS降解的重要性.最后就包气带中CHS的生物降解研究进行展望,未来研究中需要在CHS不同相态相互作用关系、包气带CHS的数据监测、功能菌群落结构及活性菌株研发方面开展研究,以期为包气带CHS原位修复提供理论指导.(图4表2参57)

It is of great significance for in-situ bioremediation to clarify the migration behavior and biodegradation laws of chlorinated hydrocarbon solvents(CHS) in the vadose zone. We systematically summarized the phase distribution of CHS, the interaction between different phases, and the migration characteristics and clarified the evolution rules of CHS under different phases in the polluted vadose zone. CHS exists in the vadose zone as the NAPL, dissolved phase, adsorbed phase, gas phase, and other phases, where there are three decay evolution stages: early, middle, and late stages. Phase change and diffusion matrix size are important indicators at different stages;at the same time, gas, solid, liquid and NAPL phase CHS have a variety of interactive relationships in the vadose zone. Subsequently, the characteristics of the three main biological metabolic pathways of CHS in the vadose zone–aerobic co-metabolism, direct oxidation and anaerobic reduction, and dechlorination–and their influencing factors were summarized. Generally speaking, the anaerobic dechlorination capacity decreases with a decrease in the number of chlorine atoms, whereas the aerobic degradation capacity increases with a decrease in the number of chlorine atoms. The current status of in-situ remediation of CHS in the vadose zone was summarized using biostimulation and bioaugmentation methods, indicating that adding nutrient substances and injecting anaerobic dechlorination strains of Dehalococcoides are effective means of remediation. Simultaneously, the factors influencing the biodegradation of CHS in the vadose zone were elaborated to acquire a systematic insight into the significance of redox characteristics(oxygen) on the degradation of CHS. Finally, research on the biodegradation of CHS in the vadose zone is prospected, and it is necessary to carry out research on the interactive relationship between different phases of CHS, the data monitoring of CHS, the structure of the functional bacterial community, and research and development of active strains to provide theoretical guidance for the in-situ remediation of CHS in the vadose zone.