Department of Civil & Environmental Engineering, University of Iowa, 4105 Seamans Center, Iowa City, IA 52242, USA.
U.S. Geological Survey, Central Midwest Water Science Center, 400 S. Clinton St, Rm 269 Federal Building, Iowa City, IA 52240, USA.
Environ Sci Process Impacts. 2021 May 26;23(5):678-688. doi: 10.1039/d1em00065a.
Neonicotinoids in aquatic systems have been predominantly associated with agriculture, but some are increasingly being linked to municipal wastewater. Thus, the aim of this work was to understand the municipal wastewater contribution to neonicotinoids in a representative, characterized effluent-dominated temperate-region stream. Our approach was to quantify the spatiotemporal concentrations of imidacloprid, clothianidin, thiamethoxam, and transformation product imidacloprid urea: 0.1 km upstream, the municipal wastewater effluent, and 0.1 and 5.1 km downstream from the wastewater outfall (collected twice-monthly for one year under baseflow conditions). Quantified results demonstrated that wastewater effluent was a point-source of imidacloprid (consistently) and clothianidin (episodically), where chronic invertebrate exposure benchmarks were exceeded for imidacloprid (36/52 samples; 3/52 > acute exposure benchmark) and clothianidin (8/52 samples). Neonicotinoids persisted downstream where mass loads were not significantly different than those in the effluent. The combined analysis of neonicotinoid effluent concentrations, instream seasonality, and registered uses in Iowa all indicate imidacloprid, and seasonally clothianidin, were driven by wastewater effluent, whereas thiamethoxam and imidacloprid urea were primarily from upstream non-point sources (or potential in-stream transformation for imidacloprid urea). This is the first study to quantify neonicotinoid persistence in an effluent-dominated stream throughout the year-implicating wastewater effluent as a point-source for imidacloprid (year-round) and clothianidin (seasonal). These findings suggest possible overlooked neonicotinoid indoor human exposure routes with subsequent implications for instream ecotoxicological exposure.
水生系统中的新烟碱类杀虫剂主要与农业有关，但也有一些与城市废水有关。因此，本研究的目的是了解代表性的、以废水为主的温带河流中城市废水对新烟碱类杀虫剂的贡献。我们的方法是定量测定吡虫啉、噻虫胺、噻虫啉和转化产物吡虫啉脲在市政污水中的时空浓度：在距离市政污水排放口上游 0.1 公里处、污水排放口以及污水排放口下游 0.1 和 5.1 公里处（在基流条件下每月采集两次，持续一年）。定量结果表明，污水是吡虫啉（持续）和噻虫胺（偶发）的点源，吡虫啉和噻虫胺的慢性无脊椎动物暴露基准均被超过（吡虫啉 36/52 个样本；3/52 个样本>急性暴露基准）。新烟碱类杀虫剂在下游持续存在，其质量负荷与污水中没有显著差异。新烟碱类杀虫剂污水排放浓度、河流季节性和爱荷华州登记用途的综合分析均表明，吡虫啉（季节性的噻虫胺）是由污水驱动的，而噻虫啉和吡虫啉脲主要来自上游非点源（或可能是河流中的转化产物）。这是首次在全年的以废水为主的河流中定量测定新烟碱类杀虫剂的持久性的研究——表明污水是吡虫啉（全年）和噻虫胺（季节性）的点源。这些发现表明，可能存在被忽视的新烟碱类杀虫剂室内人体暴露途径，对河流生态毒理学暴露具有后续影响。
