溴代阻燃剂在土壤中的迁移转化研究进展

Research Progress on Migration and Transformation of Brominated Flame Retardants in Soil

BFRs(溴代阻燃剂)是一种重要的持久性有机污染物,各种传统和新型的BFRs(PBDEs、TBBPA、DBDPE、BTBPE等)在全球环境中被广泛检出,其持久性、生物蓄积性以及对环境和人类健康的潜在毒性引起了人们的极大关注.在归纳和总结国内外关于BFRs在土壤中的迁移转化行为规律研究动态的基础上,重点讨论了吸附解吸、光降解的机理和影响因素以及厌氧、好氧微生物降解和植物代谢的特点和降解途径.结果表明:吸附/解吸是BFRs在土壤中迁移转化的关键过程,土壤有机质含量和pH是影响其在土壤中迁移的主要影响因素.光解、微生物降解是BFRs在土壤中的主要转化途径,光解是表层土壤中BFRs的主要转化过程,逐步脱溴产生低溴化产物,溴化程度、土壤有机质和矿物质会直接影响其光解速率;厌氧脱溴和好氧微生物降解是BFRs在深层土壤中的主要降解过程,溴化程度与微生物降解密切相关.土壤中BFRs被植物吸收的过程中可能被代谢为低溴化产物,在食物链中积累,危害人体健康.尽管多年来在BFRs方面的研究取得了进展,但对这类污染物的环境行为和归趋的全面了解仍然很难,随着越来越多的新型BFRs被作为传统BFRs的替代品推向市场,建议对这些新兴替代化学品在土壤介质中的迁移转化过程,特别是生物降解进行更多的调查.

BFRs(Brominated Flame Retardants)are important and persistent organic pollutants.Traditional and new BFRs such as PBDEs,TBBPA,DBDPE and BTBPE are widely detected in the global environment and their persistence,bioaccumulation,and potential toxicity are of great concern.In this paper,we summarize the research on the migration and transformation behavior of BFRs in soil in China and the world.We discuss the mechanisms and factors influencing the adsorption desorption and photodegradation of BEFs,their microbial degradation pathways and their effect on plant metabolism.The results show that adsorption desorption are the key BFR migration and transformation processes in soil and the organic matter content and pH of the soil are the main factors influencing their migration in soil.Photolysis and microbial degradation are the main transformation pathways of BFRs in soil.In surface soil,photolysis is the main BFR conversion process,wherein BFRs gradually debrominate to form lower brominated products.The degree of bromination,content of soil organic matter,and type of minerals in the soil directly affect the photolysis rate.In deep soil,anaerobic reduction debromination and aerobic microbial degradation are the main BFR degradation processes,and the degree of bromination is closely related to the microbial degradation.BFRs in the soil can be absorbed by plants,during which they may be metabolized into lower brominated products,which can accumulate in the food chain and endanger human health.Although the research on BFRs has made progress over the years,the environmental behavior and fate of these pollutants are still not fully understood.As an increasing number of new BFRs are being marketed as alternatives to traditional BFRs,further investigation is necessary on the migration and transformation processes of these emerging alternative chemicals in soil,especially biodegradation processes.