Anthropogenically modified microparticles including microplastics are present in municipal wastewater treatment plant (WWTP) effluents; however, it is unclear whether biotic exposures are elevated downstream of these outfalls. In the fall of 2019, the present study examined whether microparticle levels in resident fish, environmental samples, and caged organisms were elevated near the Waterloo and Kitchener WWTP outfalls along the Grand River, Ontario, Canada. Wild rainbow darters (Etheostoma caeruleum) were collected from a total of 10 sites upstream and downstream of both WWTPs, along with surface water and sediment samples to assess spatial patterns over an approximately 70‐km river stretch. Amphipods (Hyalella azteca), fluted‐shell mussels (Lasmigona costata), and rainbow trout (Oncorhynchus mykiss) were also caged upstream and downstream of one WWTP for 14 or 28 days. Whole amphipods, fish digestive tracts, and mussel tissues (hemolymph, digestive glands, gills) were digested with potassium hydroxide, whereas environmental samples were processed using filtration and density separation. Visual identification, measurement, and chemical confirmation (subset only) of microparticles were completed. Elevated abiotic microparticles were found at several upstream reference sites as well as at one or both wastewater‐impacted sites. Microparticles in amphipods, all mussel tissues, and wild fish did not show patterns indicative of increased exposures downstream of effluent discharges. In contrast, elevated microparticle counts were found in trout caged directly downstream of the outfall. Across all samples, cellulose fibers (mainly blue and clear colors) were the most common. Overall, results suggest little influence of WWTP effluents on microparticles in biota but rather a ubiquitous presence across most sites that indicates the importance of other point and nonpoint sources to this system. Environ Toxicol Chem 2024;00:1–15. © 2024 His Majesty the King in Right of Canada and The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC. Reproduced with the permission of the Minister of Environment and Climate Change Canada.

中文翻译：

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与大型城市污水处理厂排放相关的野生和笼养生物群、沉积物和水中的微粒

城市污水处理厂 (WWTP) 废水中存在人为修饰的微粒，包括微塑料；然而，尚不清楚这些排污口下游的生物暴露是否有所增加。2019 年秋季，本研究调查了加拿大安大略省格兰德河沿岸滑铁卢和基奇纳污水处理厂排污口附近的常住鱼类、环境样本和笼养生物中的微粒水平是否升高。野生彩虹鲈鱼（蓝口蝽）从两个污水处理厂上游和下游的总共 10 个地点收集，以及地表水和沉积物样本，以评估大约 70 公里河段的空间模式。端足类（阿兹台克鬣蜥）、槽壳贻贝（肋条藻）和虹鳟鱼（虹鳟）也被关在一个污水处理厂的上游和下游 14 或 28 天。整个片脚类、鱼类消化道和贻贝组织（血淋巴、消化腺、鳃）用氢氧化钾消化，而环境样品则通过过滤和密度分离进行处理。完成了微粒的视觉识别、测量和化学确认（仅子集）。在几个上游参考地点以及一个或两个受废水影响的地点发现非生物微粒含量升高。片脚类、所有贻贝组织和野生鱼类中的微粒没有显示出废水排放下游暴露增加的模式。相比之下，在排污口直接下游笼养的鳟鱼中发现微粒数量增加。在所有样品中，纤维素纤维（主要是蓝色和透明色）是最常见的。总体而言，结果表明污水处理厂废水对生物群中的微粒影响不大，而是在大多数地点普遍存在，这表明其他点源和非点源对该系统的重要性。环境毒理化学2024；00：1–15。© 2024 加拿大国王陛下和作者。环境毒理学和化学由 Wiley periodicals LLC 代表 SETAC 出版。经加拿大环境和气候变化部长许可转载。