Pesticides have been reported in treated wastewater effluent at concentrations that exceed aquatic toxicity thresholds, indicating that treatment may be insufficient to adequately address potential pesticide impacts on aquatic life. Gaining a better understanding of the relative contribution from specific use patterns, transport pathways, and flow characteristics is an essential first step to informing source control measures. The results of this study are the first of their kind, reporting pesticide concentrations at sub-sewershed sites within a single sewer catchment to provide information on the relative contribution from various urban sources. Seven monitoring events were collected from influent, effluent, and seven sub-sewershed sites to capture seasonal variability. In addition, samples were collected from sites with the potential for relatively large mass fluxes of pesticides (pet grooming operations, pest control operators, and laundromats). Fipronil and imidacloprid were detected in most samples (>70%). Pyrethroids were detected in >50% of all influent and lateral samples. There were significant removals of pyrethroids from the aqueous process stream within the facility to below reporting limits. Imidacloprid and fiproles were the only pesticides that were detected above reporting limits in effluent, highlighting the importance of source identification and control for the more hydrophilic compounds. Single source monitoring revealed large contributions of fipronil, imidacloprid, and permethrin originating from a pet groomer, with elevated levels of cypermethrin at a commercial laundry location. The results provide important information needed to prioritize future monitoring efforts, calibrate down-the-drain models, and identify potential mitigation strategies at the site of pesticide use to prevent introduction to sewersheds.

中文翻译：

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下水道监测以阐明下水道农药来源

据报道，经过处理的废水中的农药浓度超过了水生毒性阈值，这表明处理可能不足以充分解决农药对水生生物的潜在影响。更好地了解特定使用模式、传输路径和流量特征的相对贡献是告知源头控制措施的重要第一步。这项研究的结果是同类研究中的第一个，它报告了单个下水道集水区内下水道站点的农药浓度，以提供有关各种城市来源的相对贡献的信息。从进水口、出水口和七个下水道站点收集了七个监测事件，以捕捉季节性变化。此外，样本是从农药流量可能相对较大的地点（宠物美容店、害虫防治店和自助洗衣店）采集的。大多数样品 (>70%) 中检测到氟虫腈和吡虫啉。在 >50% 的所有进水和横向样本中检测到拟除虫菊酯。设施内水性工艺流中拟除虫菊酯的去除量显着低于报告限值。吡虫啉和氟虫腈是唯一在流出物中检测到超过报告限值的杀虫剂，这凸显了对亲水性更强的化合物进行源识别和控制的重要性。单一来源监测显示氟虫腈、吡虫啉和氯菊酯的大量来源来自宠物美容师，而商业洗衣店的氯氰菊酯含量较高。