While microplastic inputs into rivers are assumed to be correlated with anthropogenic activities and to accumulate towards the sea, the impacts of water management on downstream microplastic transport are largely unexplored. A comparative study of microplastic abundance in Boulder Creek (BC), and its less urbanized tributary South Boulder Creek (SBC), (Colorado USA), characterized the downstream evolution of microplastics in surface water and sediments, evaluating the effects of urbanization and flow diversions on the up-to-downstream profiles of microplastic concentrations and loads. Water and sediment samples were collected from 21 locations along both rivers and microplastic properties determined by fluorescence microscopy and Raman spectroscopy. The degree of catchment urbanization affected microplastic patterns, as evidenced by greater water and sediment concentrations and loads in BC than the less densely populated SBC, which is consistent with the differences in the degree of urbanization between both catchments. Microplastic removal through flow diversions was quantified, showing that water diversions removed over 500 microplastic particles per second from the river, and caused stepwise reductions of downstream loads at diversion points. This redistribution of microplastics back into the catchment should be considered in large scale models quantifying plastic fate and transport to the oceans.

虽然假设进入河流的微塑料与人类活动相关并向海洋积累，但水资源管理对下游微塑料运输的影响在很大程度上尚未得到探索。博尔德溪 (BC) 及其城市化程度较低的支流南博尔德溪 (SBC)（美国科罗拉多州）的微塑料丰度比较研究，表征了地表水和沉积物中微塑料的下游演变，评估了城市化和流量改道的影响关于微塑料浓度和负载的上下游分布。从河流沿岸的 21 个地点收集了水和沉积物样本，并通过荧光显微镜和拉曼光谱确定了微塑料的特性。流域城市化程度影响微塑料模式，BC 的水和沉积物浓度和负荷比人口密度较低的 SBC 更高，这与两个流域之间城市化程度的差异一致。通过分流对微塑料的去除进行了量化，表明分流每秒从河流中去除了 500 多个微塑料颗粒，并导致分流点的下游负荷逐步减少。在量化塑料归宿和向海洋运输的大型模型中，应考虑将微塑料重新分配回集水区。表明改道每秒从河流中去除 500 多个微塑料颗粒，并导致分流点的下游负荷逐步减少。在量化塑料归宿和向海洋运输的大型模型中，应考虑将微塑料重新分配回集水区。表明改道每秒从河流中去除 500 多个微塑料颗粒，并导致分流点的下游负荷逐步减少。在量化塑料归宿和向海洋运输的大型模型中，应考虑将微塑料重新分配回集水区。