Per- and polyfluoroalkyl substances (PFAS) are extensively used in urban environments and are, thus, found in urban stormwater. However, the relevance of stormwater as a pathway for PFAS to urban streams is largely unknown. This study evaluated the impact of urban stormwater runoff on PFAS concentrations and spatial distribution in three urban streams affected by stormwater discharges from separate sewer systems. River water was sampled during dry (DW) and wet weather (WW) upstream, immediately downstream, and further downstream of three urbanized areas with separate sewer systems and with and without point sources (i.e. waste water treatment plant, airports). Water samples were analyzed for 34 targeted PFAS compounds and sediment samples for 35 targeted PFAS and 30 PFAS compounds using a total oxidizable precursor assay. The sum of the quantified PFAS concentrations ranged from the reporting limit (RL) to 84.7 ng/L during DW and increased as the streams were affected by WW discharges (0.87 to 102.3 ng/L). The highest PFAS concentrations were found downstream of urban areas and/or point sources (i.e. airports) during WW, indicating a clear contribution from stormwater discharges. A consistent PFAS contribution from the WWTP was observed under both DW and WW conditions. During WW events, concentrations of perfluorooctanesulfonic acid (PFOS) and total PFAS (PFOA equivalents) exceeded the annual average environmental quality standards, which are an established limit of 0.65 ng/L for PFOS and a proposed limit of 4.4 ng/L for total PFAS. Notably, except for the legacy PFAS, PFOS and perfluorooctanoic acid (PFOA), the most frequently quantified PFAS during DW were short-chain. For WW, long-chain perfluorocarboxylic acids (PFCAs) and a precursor, 6:2 Fluorotelomer sulfonic acid (6:2 FTS), were more frequently quantified, suggesting stormwater is a source of these longer-chain and particle-associated PFAS. The detection of unregulated fluorotelomer sulfonates (FTSs) such as 6:2 and 8:2 FTS during WW suggests a need for regulatory action, as these compounds can degrade into more stable PFAS. In sediment, higher concentrations, and a greater variety of PFAS were found at sites with known point sources i.e. airports. Long-chain PFCAs (C7-C13), perfluoroalkyl sulfonates (PFSAs) (C6), and precursors (i.e. N-Ethyl perfluorooctane sulfonamidoacetic acid), were more prevalent in sediments than in the water. Notably, PFOS concentrations in sediment exceeded the lowest Predicted No-Effect Concentration (PNEC) across sites, posing a potential long-term environmental risk, though current PNECs for other PFAS may underestimate such risks. The findings of the study highlight urban stormwater as a source of PFAS to urban streams indicating the need to minimize PFAS sources in the urban environment and to effectively treat stormwater to protect receiving water bodies.

中文翻译：

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雨水排放会影响 PFAS 在城市溪流水和底部沉积物中的发生、浓度和空间分布


全氟烷基和多氟烷基物质 （PFAS） 广泛用于城市环境，因此也存在于城市雨水中。然而，雨水作为 PFAS 进入城市溪流的途径的相关性在很大程度上是未知的。本研究评估了城市雨水径流对受独立下水道系统雨水排放影响的三条城市溪流中 PFAS 浓度和空间分布的影响。在干燥 （DW） 和潮湿天气 （WW） 期间，对三个城市化地区的上游、直接下游和下游进行采样，这些地区具有独立的下水道系统，有和没有点源（即废水处理厂、机场）。使用总可氧化前体分析法分析水样中的 34 种目标 PFAS 化合物，分析沉积物样品中的 35 种目标 PFAS 和 30 种 PFAS 化合物。在 DW 期间，定量 PFAS 浓度的总和范围从报告限 （RL） 到 84.7 ng/L，并且随着流受 WW 排放的影响（0.87 至 102.3 ng/L）而增加。在 WW 期间，城市地区下游和/或点源（即机场）的 PFAS 浓度最高，表明雨水排放有明显的贡献。在 DW 和 WW 条件下观察到 WWTP 对 PFAS 的贡献一致。在 WW 事件期间，全氟辛烷磺酸 （PFOS） 和总 PFAS（PFOA 当量）的浓度超过了年平均环境质量标准，该标准是 PFOS 的既定限值 0.65 ng/L，总 PFAS 的建议限值为 4.4 ng/L。值得注意的是，除了传统的 PFAS、PFOS 和全氟辛酸 （PFOA） 外，DW 期间最常定量的 PFAS 是短链。 对于 WW，长链全氟羧酸 （PFCA） 和前体 6：2 含氟调聚物磺酸 （6：2 FTS） 的定量频率更高，这表明雨水是这些长链和颗粒相关 PFAS 的来源。在 WW 过程中检测到不受管制的含氟调聚物磺酸盐 （FTS），例如 6：2 和 8：2 FTS，这表明需要采取监管行动，因为这些化合物可以降解成更稳定的 PFAS。在沉积物中，在具有已知点源的地点（即机场）发现了更高浓度和更多种类的 PFAS。长链 PFCA （C7-C13）、全氟烷基磺酸盐 （PFSA） （C6） 和前体（即 N-乙基全氟辛烷磺酰胺乙酸）在沉积物中比在水中更普遍。值得注意的是，沉积物中的 PFOS 浓度超过了各地点的最低预测无影响浓度 （PNEC），构成了潜在的长期环境风险，尽管目前其他 PFAS 的 PNEC 可能低估了此类风险。研究结果强调，城市雨水是城市溪流中 PFAS 的来源，表明需要最大限度地减少城市环境中的 PFAS 来源，并有效处理雨水以保护受纳水体。