Choi Youn Jeong, Helbling Damian E, Liu Jinxia, Olivares Christopher I, Higgins Christopher P
Department of Civil and Environmental Engineering, Colorado School of Mines, Golden, CO, USA; Department of Agronomy, Purdue University, West Lafayette, IN, USA.
School of Civil and Environmental Engineering, Cornell University, Ithaca, NY, USA.
Sci Total Environ. 2022 Jun 10;824:153711. doi: 10.1016/j.scitotenv.2022.153711. Epub 2022 Feb 8.
Per- and polyfluoroalkyl substances (PFASs) used in aqueous film-forming foam (AFFF) comprise some perfluoroalkyl substances but a larger variety of polyfluoroalkyl substances. Despite their abundance in AFFF, information is lacking on the potential transformation of these polyfluoroalkyl substances. Due to the biological and chemical stability of the repeating perfluoroalkyl -(CF)- moiety common to all known AFFF-derived PFASs, it is not immediately evident whether the microbial biotransformation mechanisms observed for other organic contaminants also govern the microbial biotransformation of polyfluoroalkyl substances. Herein, we aim to: 1) review the literature on the aerobic or anaerobic microbial biotransformation of AFFF-derived polyfluoroalkyl substances in environmental media; 2) compile and summarize proposed microbial biotransformation pathways for major classes of polyfluoroalkyl substances; 3) identify the dominant biotransformation intermediates and terminal biotransformation products; and 4) discuss these findings in the context of environmental monitoring and source allocation. This analysis revealed that much more is currently known about aerobic microbial biotransformation of polyfluoroalkyl substances, as compared to anaerobic biotransformation. Further, there are some similarities in microbial biotransformations of fluorotelomer and electrochemical fluorination-derived polyfluoroalkyl substances, but differences may be largely due to head group composition. Dealkylation, oxidation, and hydrolytic reactions appear to be particularly important for microbial biotransformation of AFFF-derived polyfluoroalkyl substances, and these biotransformations may lead to formation of some semi-stable intermediates. Finally, this review discusses key knowledge gaps and opportunities for further research.
用于水成膜泡沫（AFFF）的全氟和多氟烷基物质（PFASs）包含一些全氟烷基物质，但种类更多的是多氟烷基物质。尽管它们在AFFF中含量丰富，但关于这些多氟烷基物质的潜在转化的信息却很缺乏。由于所有已知的源自AFFF的PFASs共有的重复全氟烷基-（CF）-部分具有生物和化学稳定性，对于其他有机污染物所观察到的微生物生物转化机制是否也适用于多氟烷基物质的微生物生物转化，目前尚不清楚。在此，我们旨在：1）综述环境介质中源自AFFF的多氟烷基物质的好氧或厌氧微生物生物转化的文献；2）汇编和总结主要类别的多氟烷基物质的拟议微生物生物转化途径；3）确定主要的生物转化中间体和最终生物转化产物；4）在环境监测和源分配的背景下讨论这些发现。该分析表明，与厌氧生物转化相比，目前对多氟烷基物质的好氧微生物生物转化了解得更多。此外，氟调聚物和电化学氟化衍生的多氟烷基物质的微生物生物转化存在一些相似之处，但差异可能主要归因于端基组成。脱烷基化、氧化和水解反应对于源自AFFF的多氟烷基物质的微生物生物转化似乎特别重要，并且这些生物转化可能导致形成一些半稳定的中间体。最后，本综述讨论了关键的知识空白和进一步研究的机会。
