Department of Civil, Environmental, and Geo- Engineering, University of Minnesota, 500 Pillsbury Drive SE, Minneapolis, Minnesota 55455, USA.
School of Public Health, University of Minnesota, 420 Delaware St. S.E., Minneapolis, MN 55455, USA.
Environ Sci Process Impacts. 2019 Nov 1;21(11):1915-1925. doi: 10.1039/c9em00241c. Epub 2019 Aug 27.
Aqueous film forming foams (AFFF) can contain gram per liter concentrations of per- and polyfluoroalkyl substances (PFAS) and are often released in large quantities directly to the environment as they are used to fight fires. AFFF composition is complex and contains many unknown PFAS in addition to ingredients such as hydrocarbons, solvents, and corrosion inhibitors. While biological effects of single PFAS have been studied, the effects of PFAS-containing mixtures, such as AFFF, are unknown. The effect of PFAS on microorganisms is also not well understood; nevertheless, we rely on microorganisms in locations containing elevated PFAS concentrations to perform certain functions, such as carbon cycling and co-contaminant degradation. This study focused on determining the functional consequences of AFFF and PFAS exposure in a microbial community in both the presence and the absence of a co-contaminant. AFFF, select PFAS, and a PFAS mixture were tested to determine the effect of AFFF on an anaerobic microbial community and the characteristics of the PFAS that drive toxicity in such mixtures. To study this, anaerobic digester communities were exposed to PFAS and a co-contaminant (2,4-dichlorophenol, DCP); methane production, as an indicator of toxicity and the community's ability to cycle carbon, and co-contaminant degradation were monitored. Results showed that PFAS and AFFF can alter the toxicity of DCP, inhibit DCP degradation, decrease the number of methanogens present, and change the microbial community structure. DCP was also able to decrease the toxicity of the PFAS perfluorooctane sulfonate (PFOS), possibly by changing the sorption of PFOS to the microorganisms present. Additionally, it was determined that while PFOS was responsible for AFFF toxicity, no single PFAS or simple PFAS mixture accurately accounted for the inhibition of DCP degradation caused by AFFF exposure.
水成膜泡沫（AFFF）中每升可含有微克到克数量级的全氟和多氟烷基物质（PFAS），而且在大量直接排放到环境中时，它们通常被用来灭火。AFFF 的成分复杂，除了碳氢化合物、溶剂和缓蚀剂等成分外，还含有许多未知的 PFAS。虽然已经研究了单一 PFAS 的生物效应，但 PFAS 混合物（如 AFFF）的影响尚不清楚。PFAS 对微生物的影响也不为人知；然而，我们依赖于含有高浓度 PFAS 的地点中的微生物来执行某些功能，例如碳循环和共污染物降解。本研究重点研究了在存在和不存在共污染物的情况下，AFFF 和 PFAS 暴露对微生物群落的功能后果。研究了 AFFF、选定的 PFAS 和 PFAS 混合物，以确定 AFFF 对厌氧微生物群落的影响以及在这种混合物中导致毒性的 PFAS 的特性。为了研究这一点，将厌氧消化器群落暴露于 PFAS 和共污染物（2,4-二氯苯酚，DCP）；监测甲烷产生，作为毒性和群落循环碳能力的指标，以及共污染物降解。结果表明，PFAS 和 AFFF 可以改变 DCP 的毒性，抑制 DCP 降解，减少存在的产甲烷菌数量，并改变微生物群落结构。DCP 还能够降低全氟辛烷磺酸（PFOS）的毒性，可能是通过改变 PFOS 与存在的微生物的吸附作用。此外，还确定虽然 PFOS 是 AFFF 毒性的原因，但没有单一的 PFAS 或简单的 PFAS 混合物能够准确说明 AFFF 暴露对 DCP 降解抑制的原因。
