Department of Chemistry, Valparaiso University, 1710 Chapel Drive, Valparaiso, IN 46383, USA.
Environ Sci Process Impacts. 2019 Sep 18;21(9):1549-1559. doi: 10.1039/c9em00193j.
Microplastic waste is a worldwide problem, heavily afflicting marine and freshwater environments; the loading of this pollution in water, sediment and living organisms continues to escalate. Synthetic microfibers, resulting from the release of microscopic fibers from synthetic textiles, constitute the most prevalent type of microplastics pollution in aquatic environments. This study investigated the origin and distribution of synthetic microfibers in a representative Lake Michigan watershed in Indiana (USA) by analyzing water, sediment and air samples above and below wastewater treatment plant discharges, downstream in the watershed and water from the Lake Michigan shoreline. Synthetic microfibers were also quantified in wastewater from a local wastewater treatment plant (WWTP) and in laundry effluent. Laboratory testing of numerous fabrics suggests that Fenton oxidation, used to break down natural fibers, effectively eliminates non-polluting, natural fibers from the samples. However, the hydroxyl radical-mediated oxidation bleaches the dye from certain synthetic microfibers, which likely leads to under-reported values for these microplastics in natural samples. The data collected from the watershed samples indicate that approximately 4 billion synthetic microfibers are transported daily through the Lake Michigan tributary. Wastewater effluent is not the only source of synthetic microfibers, since surface water samples above the WWTP contained a similar load to downstream samples. Repeated sampling exhibited variability in the number of microfibers detected, substantiating the heterogeneous distribution of these pollutants and the requirement for multiple samples for a given site. The average load of synthetic microfibers from water sampled at the Lake Michigan shoreline was higher than the tributary water, suggesting the shoreline functions as a repository for the microfibers. Given the extent and potential consequences of this pollution, quantification of the ubiquitous plastic fibers can be instituted as part of the traditional total suspended solids (TSS) water quality monitoring parameter.
微塑料废物是一个全球性的问题，严重影响着海洋和淡水环境；这种污染物在水、沉积物和生物体内的负荷不断加剧。合成微纤维是由合成纺织品释放的微小纤维组成，是水生环境中最普遍的微塑料污染类型。本研究通过分析污水处理厂排放口上下游、流域下游以及密歇根湖湖岸的水、沉积物和空气样本，调查了美国印第安纳州密歇根湖流域一个代表性流域中合成微纤维的来源和分布。还对当地污水处理厂（WWTP）的废水和洗衣污水中的合成微纤维进行了定量分析。对大量织物进行的实验室测试表明，用于分解天然纤维的芬顿氧化有效地从样品中去除了无污染的天然纤维。然而，羟基自由基介导的氧化会使某些合成微纤维的染料褪色，这可能导致天然样品中这些微塑料的报告值偏低。从流域样本中收集的数据表明，每天约有 40 亿根合成微纤维通过密歇根湖支流输送。废水并不是合成微纤维的唯一来源，因为 WWTP 上方的地表水样本与下游样本的负荷相似。重复采样显示出检测到的微纤维数量存在差异，这证实了这些污染物的不均匀分布以及对给定地点进行多次采样的必要性。从密歇根湖湖岸采集的水样中检测到的合成微纤维平均负荷高于支流水，这表明湖岸是这些微纤维的储存库。鉴于这种污染的程度和潜在后果，可以将无处不在的塑料纤维的量化作为传统总悬浮固体（TSS）水质监测参数的一部分。
