Central Wyoming College, Department of Arts and Sciences, PO Box 4795, Jackson, WY, 83001, USA.
Central Wyoming College, Department of Arts and Sciences, PO Box 4795, Jackson, WY, 83001, USA; University of Wyoming, Department of Agricultural and Applied Economics, 1000 E. University Ave., Laramie, WY, 82071, USA.
Environ Pollut. 2018 Oct;241:1082-1090. doi: 10.1016/j.envpol.2018.06.033. Epub 2018 Jun 13.
It is widely understood that microplastics (MPs) are ubiquitous in the marine environment yet less is known about MP abundance in freshwater rivers, particularly those of the western United States. This study documents MP pollution along the Snake River (∼1735 km) and from its confluence with the Columbia River to the Pacific Ocean. Grab and plankton net samples (mesh size 100 μm) were collected from the top 25 cm of surface water every 80.5 river km. MPs were identified if they met visual criteria and were verified with the hot needle test. A small representative subset of MPs from the net samples (16.7%) were selected based on appearance for micro-Raman spectroscopy in effort to provide examples of polymer types found in this study. Seventy-five percent of grab samples and 92.8% of net samples contained MPs, with concentrations ranging from 0 to 5.405 MP L and 0 to 0.014 MP L (0 to 13.7 MP m), respectively. The majority of fragments, films and beads were between 100 μm and 333 μm. This study identifies potential hotspots of MP pollution along the Snake and Lower Columbia rivers and prioritizes areas where more intensive sampling is needed. Sites with low flow or those further down river had higher numbers and the top two hotspots were located in areas with low population density but high agricultural use. Monitoring MP abundance in freshwater systems is important for establishing baseline levels of MP pollution and can direct laboratory toxicology studies in using more environmentally relevant concentrations for a better indication of how MP pollution affects ecosystems.
人们普遍认为，微塑料（MPs）在海洋环境中无处不在，但对于美国西部淡水河流中 MP 的丰度知之甚少。本研究记录了蛇河（约 1735 公里）及其与哥伦比亚河的汇合处到太平洋的 MP 污染情况。从地表水表面以下 25 厘米处每隔 80.5 公里采集抓取和浮游生物网样本（网眼尺寸 100μm）。如果 MPs 符合视觉标准，并通过热针测试进行验证，则将其识别出来。根据网样中 MPs 的外观，选择一小部分（16.7%）具有代表性的 MPs 进行微拉曼光谱分析，以提供本研究中发现的聚合物类型的示例。75%的抓取样品和 92.8%的网样中含有 MPs，浓度范围分别为 0 至 5.405 MPs/L 和 0 至 0.014 MPs/L（0 至 13.7 MPs/m）。大多数碎片、薄膜和珠粒的尺寸在 100μm 到 333μm 之间。本研究确定了蛇河和下哥伦比亚河沿岸潜在的 MP 污染热点，并确定了需要更密集采样的优先区域。低流量或更下游的地点的数量更高，两个热点都位于人口密度低但农业使用率高的地区。监测淡水系统中 MP 的丰度对于确定 MP 污染的基线水平很重要，并且可以指导实验室毒理学研究使用更具环境相关性的浓度，以更好地指示 MP 污染对生态系统的影响。
