Röhler Klaus, Susset Bernd, Grathwohl Peter
Department of Geosciences, University of Tübingen, Schnarrenbergstraße 94-96, 72076 Tübingen, Germany.
Department of Geosciences, University of Tübingen, Schnarrenbergstraße 94-96, 72076 Tübingen, Germany.
Sci Total Environ. 2023 Dec 1;902:166555. doi: 10.1016/j.scitotenv.2023.166555. Epub 2023 Aug 24.
Contamination of soils with per- and polyfluoroalkyl substances (PFAS) (e.g., aqueous film forming foams (AFFFs) or PFAS containing biosolids applied to agricultural soils) can lead to large scale groundwater pollution. For site management, knowledge about the extent and time scales of PFAS contamination is crucial. At such sites, often persistent perfluoroalkyl acids (PFAAs) and so-called precursors, which can be transformed into PFAAs, co-occur. In this study, the release of PFAAs from 14 soil samples from an agricultural site in southwest Germany contaminated via compost/paper sludge was investigated. Rapid leaching of C4-C8 perfluoroalkyl carboxylic acids (PFCA) was observed in saturated column tests, while slowing down with increasing chain-length (≥ C9 PFCAs). Two selected samples were further incubated in batch-tests after removal of existing C4-C8 PFCAs in extensive column leaching tests until a liquid-solid ratio of 10 l/kg. During 60 days of incubation, aqueous concentrations of C4-C8 PFCAs increased linearly by a factor of 29-222, indicating continuous production by transformation of precursors. The potential PFAA-precursor reservoir was estimated by the direct total oxidizable precursor (dTOP) assay. PFCA concentrations after the dTOP increased up to two orders of magnitude. Production rates determined in batch-tests combined with the results of dTOP assay were used to estimate time scales for the duration of C4-C8 PFCAs emission from the contaminated agricultural soils which likely will last for several decades.
全氟和多氟烷基物质（PFAS）对土壤的污染（例如，水成膜泡沫灭火剂（AFFFs）或用于农业土壤的含PFAS生物固体）会导致大规模的地下水污染。对于场地管理而言，了解PFAS污染的范围和时间尺度至关重要。在这些场地，通常会同时存在持久性全氟烷基酸（PFAA）和所谓的前体物质，这些前体物质可以转化为PFAA。在本研究中，对德国西南部一个农业场地的14个土壤样品中PFAA的释放情况进行了调查，这些土壤样品通过堆肥/纸污泥受到了污染。在饱和柱试验中观察到C4 - C8全氟烷基羧酸（PFCA）的快速淋溶，而随着链长增加（≥ C9 PFCA）淋溶速度减慢。在广泛的柱淋溶试验中去除现有的C4 - C8 PFCA后，对两个选定的样品进行了进一步的批次试验培养，直至液固比达到10 l/kg。在60天的培养过程中，C4 - C8 PFCA的水溶液浓度线性增加了29 - 222倍，表明前体物质转化导致其持续产生。通过直接总可氧化前体（dTOP）测定法估算了潜在的PFAA - 前体物质库。dTOP测定后的PFCA浓度增加了两个数量级。结合dTOP测定结果在批次试验中确定的产生速率，用于估算受污染农业土壤中C4 - C8 PFCA排放持续的时间尺度，这可能会持续数十年。
