Department of Chemistry, 1710 Chapel Drive, Valparaiso University, Valparaiso, IN, 46383, USA.
U.S. Geological Survey, Great Lakes Science Center, Chesterton, IN, 46304, USA.
Environ Pollut. 2021 May 1;276:116695. doi: 10.1016/j.envpol.2021.116695. Epub 2021 Feb 10.
Daunting amounts of microplastics are present in surface waters worldwide. A main category of microplastics is synthetic microfibers, which originate from textiles. These microplastics are generated and released in laundering and are discharged by wastewater treatment plants or enter surface waters from other sources. The polymers that constitute many common synthetic microfibers are mostly denser than water, and eventually settle out in aquatic environments. The interaction of these microfibers with submerged aquatic vegetation has not been thoroughly investigated but is potentially an important aquatic sink in surface waters. In the Laurentian Great Lakes, prolific growth of macrophytic Cladophora creates submerged biomass with a large amount of surface area and the potential to collect and concentrate microplastics. To determine the number of synthetic microfibers in Great Lakes Cladophora, samples were collected from Lakes Erie and Michigan at multiple depths in the spring and summer of 2018. After rinsing and processing the algae, associated synthetic microfibers were quantified. The average loads of synthetic microfibers determined from the Lake Erie and Lake Michigan samples were 32,000 per kg (dry weight (dw)) and 34,000 per kg (dw), respectively, 2-4 orders of magnitude greater than loads previously reported in water and sediment. To further explore this sequestration of microplastics, fresh and aged Cladophora were mixed with aqueous mixtures of microfibers or microplastic in the laboratory to simulate pollution events. Microscopic analyses indicated that fresh Cladophora algae readily interacted with microplastics via adsorptive forces and physical entanglement. These interactions mostly cease upon algal senescence, with an expected release of microplastics in benthic sediments. Collectively, these findings suggest that synthetic microfibers are widespread in Cladophora algae and the affinity between microplastics and Cladophora may offer insights for removing microplastic pollution. Macroalgae in the Laurentian Great Lakes contain high loads of synthetic microfibers, both entangled and adsorbed, which likely account for an important fraction of microplastics in these surface waters.
全世界的地表水都存在大量的微塑料。微塑料的一个主要类别是合成微纤维，它们来源于纺织品。这些微塑料在洗涤过程中产生并释放出来，并通过废水处理厂排放，或者从其他来源进入地表水。构成许多常见合成微纤维的聚合物大多比水密度大，最终在水生环境中沉淀下来。这些微纤维与水下植被的相互作用尚未得到彻底研究，但它们可能是地表水的一个重要水下汇。在北美五大湖地区，繁茂生长的大型丝状绿藻 Cladophora 形成了具有大量表面积的水下生物量，具有收集和浓缩微塑料的潜力。为了确定五大湖 Cladophora 中的合成微纤维数量，于 2018 年春夏两季在伊利湖和密歇根湖的多个深度采集了样本。对藻类进行冲洗和处理后，对相关的合成微纤维进行了量化。从伊利湖和密歇根湖样本中确定的合成微纤维平均负荷分别为每公斤（干重 (dw))32,000 根和 34,000 根，分别是以前在水和沉积物中报告的负荷的 2-4 个数量级。为了进一步探索这种微塑料的隔离作用，新鲜的和老化的 Cladophora 与微纤维或微塑料的水相混合物在实验室中混合，以模拟污染事件。显微镜分析表明，新鲜的 Cladophora 藻类通过吸附力和物理缠结与微塑料很容易相互作用。这些相互作用在藻类衰老时大多停止，预计微塑料会在底泥中释放。总的来说，这些发现表明，合成微纤维在 Cladophora 藻类中广泛存在，微塑料与 Cladophora 之间的亲和力可能为去除微塑料污染提供新的思路。劳伦森大湖中的大型藻类含有大量的合成微纤维，既有缠绕的也有吸附的，这些微纤维可能构成这些地表水微塑料的重要组成部分。
