Department of Civil and Environmental Engineering, University of California, Berkeley, California 94720, United States.
Department of Civil and Environmental Engineering, University of California, Irvine, California 92697, United States.
Environ Sci Technol. 2022 Nov 15;56(22):15478-15488. doi: 10.1021/acs.est.2c00261. Epub 2022 Oct 18.
Sites impacted by aqueous film-forming foam (AFFF) contain co-contaminants that can stimulate biotransformation of polyfluoroalkyl substances. Here, we compare how microbial enrichments from AFFF-impacted soil amended with diethyl glycol monobutyl ether (found in AFFF), aromatic hydrocarbons (present in co-released fuels), acetate, and methane (substrates used or formed during bioremediation) impact the aerobic biotransformation of an AFFF-derived six-carbon electrochemical fluorination (ECF) precursor -dimethyl ammonio propyl perfluorohexane sulfonamide (AmPr-FHxSA). We found that methane- and acetate-oxidizing cultures resulted in the highest yields of identifiable products (38 and 30%, respectively), including perfluorohexane sulfonamide (FHxSA) and perfluorohexane sulfonic acid (PFHxS). Using these data, we propose and detail a transformation pathway. Additionally, we examined chemical oxidation products of AmPr-FHxSA and FHxSA to provide insights on remediation strategies for AmPr-FHxSA. We demonstrate mineralization of these compounds using the sulfate radical and test their transformation during the total oxidizable precursor (TOP) assay. While perfluorohexanoic acid accounted for over 95% of the products formed, we demonstrate here for the first time two ECF-based precursors, AmPr-FHxSA and FHxSA, that produce PFHxS during the TOP assay. These findings have implications for monitoring poly- and perfluoroalkyl substances during site remediation and application of the TOP assay at sites impacted by ECF-based precursors.
受水成膜泡沫（AFFF）影响的地点含有共污染物，这些污染物可以刺激多氟烷基物质的生物转化。在这里，我们比较了受 AFFF 影响的土壤中微生物富集物，这些土壤中添加了二乙二醇单丁醚（存在于 AFFF 中）、芳烃（在共释放的燃料中存在）、乙酸盐和甲烷（生物修复过程中使用或形成的底物）对 AFFF 衍生的六碳电化学氟化（ECF）前体-二甲基氨丙基全氟己烷磺酰胺（AmPr-FHxSA）的需氧生物转化的影响。我们发现，甲烷和乙酸盐氧化培养物产生的可识别产物的产率最高（分别为 38%和 30%），包括全氟己烷磺酰胺（FHxSA）和全氟己烷磺酸（PFHxS）。利用这些数据，我们提出并详细描述了一种转化途径。此外，我们还研究了 AmPr-FHxSA 和 FHxSA 的化学氧化产物，以提供有关 AmPr-FHxSA 修复策略的见解。我们使用硫酸根自由基证明了这些化合物的矿化，并在总可氧化前体（TOP）测定中测试了它们的转化。虽然全氟己酸占形成产物的 95%以上，但我们在这里首次证明了两种 ECF 为基础的前体，AmPr-FHxSA 和 FHxSA，在 TOP 测定中会产生 PFHxS。这些发现对监测多氟和全氟烷基物质在现场修复期间以及在受 ECF 为基础的前体影响的地点应用 TOP 测定时具有重要意义。
