We examined the influence of point and nonpoint source contamination on microplastic (MP) levels in water, macroinvertebrates, and trout in a small, cold‐water stream in western Wisconsin, U.S.A. We collected samples along an urbanization gradient centered around a 6‐mile corridor that receives numerous MP inputs from stormwater outfalls and a wastewater plant. We digested samples using a wet peroxide oxidation method. Particles filtered from digestates were stained with Nile Red dye, then viewed using fluorescence microscopy. We quantified fluorescing MPs using ImageJ software. MP concentrations in water increased significantly from upstream to downstream reaches and appeared to influence organism MP levels. Macroinvertebrates and trout collected upstream of the city had significantly lower MP levels than macroinvertebrates and trout collected within the city, and for trout, downstream of the city. MP particle lengths were significantly longer in macroinvertebrates compared to water and trout, perhaps indicating preferential accumulation of longer particles from the water column.

中文翻译：

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城市点源污染对冷水流中水和生物中的微量塑料含量的影响

我们检查了点源和非点源污染对美国威斯康星州西部一小条冷水流中水，大型无脊椎动物和鳟鱼中微量（MP）含量的影响，我们沿着以6英里长的走廊为中心的城市化梯度收集了样本从雨水排放口和废水处理厂获得大量的MP投入。我们使用湿式过氧化物氧化方法消化了样品。从消化液中滤出的颗粒用尼罗红染料染色，然后使用荧光显微镜观察。我们使用ImageJ软件对发荧光的MP进行了定量。从上游到下游，水中的MP浓度显着增加，并且似乎影响生物MP的水平。在城市上游采集的大型无脊椎动物和鳟鱼的MP水平明显低于在城市内部采集的大型无脊椎动物和鳟鱼，对于城市下游的鳟鱼而言。与水和鳟鱼相比，大型无脊椎动物的MP颗粒长度明显更长，这可能表明水柱中较长颗粒的优先积累。