摘要

众所周知，水坝能在沉积物中捕获污染物，如金属和多氯联苯，这些污染物在水库内积累。随着人们越来越关注微塑料，这是世界范围水道中的一种新污染物，以及它们是如何沿着河流移动的，微塑料粒子是否在水坝后面堆积也是一个重要的问题，可以为全球河流对海洋投入的估算提供信息。在这项研究中，我们在美国纽约州伊萨卡附近的6个水坝的蓄水池中，测量了上面、下面和水库内的微塑料浓度。样品采用湿过氧化物氧化法和目测计数法处理，然后进行拉曼光谱验证。结果表明，水库底泥中微塑性浓度显著高于大坝以上沉积物(p=0.005)，水样中微塑性浓度显著低于水库内(p=0.02)。塑料纤维是主要的塑性类型，但在水库内沉积物样品中，塑料碎片等塑性类型较少，比例较高。这些结果表明，在长时间下，坝后的沉淀物收集在河流系统中会形成一个微塑料的坑，这表明当模拟全球河流微塑料输送时，考虑核算水坝的作用可能是很重要的。

      Dams are known to trap pollutants such as metals and PCBs in the sediment that accumulates within their reservoirs. As more attention is paid to microplastics, an emerging contaminant in waterways worldwide, and how they move along rivers, whether microplastic particles also accumulate behind dams is an important question for informing estimates of global river inputs to oceans. In this study, we measured microplastic concentrations above, below, and within the reservoirs of six dams near Ithaca, NY USA. Samples were processed following the wet peroxide oxidation method and visual counting, followed by Raman Spectroscopy validation. We found that microplastic concentrations in sediment within reservoirs was significantly higher than in sediment above the dams (p = 0.005), and in water samples, concentrations within reservoirs was significantly lower (p = 0.02). Plastic fibers were the dominant plastic type, but in within-reservoir sediment samples, less abundant plastic types such as plastic fragments were found in higher proportions. These results show that the sediment collecting behind dams is one sink for microplastics in river systems at long timescales, indicating that accounting for dams may be important when modeling global riverine microplastic transport.