Department of Civil and Mineral Engineering, University of Toronto, 35St. George Street, Toronto ON M5S 1A4, Canada.
Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto ON M5S 3E5, Canada.
Water Res. 2021 Mar 1;191:116785. doi: 10.1016/j.watres.2020.116785. Epub 2020 Dec 26.
Microplastic pathways in the environment must be better understood to help select appropriate mitigation strategies. In this 2-year long field study, microplastics were characterized and quantified in urban stormwater runoff and through a bioretention cell, a type of low impact development infrastructure. Concentrations of microparticles ranged from below the detection limit to 704 microparticles/L and the dominant morphology found were fibers. High rainfall intensity and longer antecedent dry days resulted in larger microparticle concentrations. In addition, atmospheric deposition was a source of microplastics to urban runoff. Overall, these results demonstrate that urban stormwater runoff is a concentrated source of microplastics whose concentrations depend on specific climate variables. The bioretention cell showed an 84% decrease in median microparticle concentration in the 106-5,000 µm range, and thus is effective in filtering out microplastics and preventing their spread to downstream environments. Altogether, these results highlight the large contribution of urban stormwater runoff to microplastic contamination in larger aquatic systems and demonstrate the potential for current infiltration-based low impact development practices to limit the spread of microplastic contamination downstream.
为了帮助选择合适的缓解策略，必须更好地了解环境中的微塑料迁移途径。在这项为期两年的野外研究中，对城市雨水径流和生物滞留池（一种低影响开发基础设施）中的微塑料进行了特征描述和量化。微粒子的浓度范围从检测限以下到 704 个微粒子/升，发现的主要形态是纤维。高强度降雨和较长的前期干燥天数导致微粒子浓度增大。此外，大气沉降也是城市径流中微塑料的一个来源。总的来说，这些结果表明城市雨水径流是微塑料的集中来源，其浓度取决于特定的气候变量。生物滞留池对 106-5000µm 范围内的微粒子的浓度中位数降低了 84%，因此能够有效地过滤微塑料并防止其扩散到下游环境。总之，这些结果突出了城市雨水径流对更大的水生系统中微塑料污染的巨大贡献，并证明了当前基于渗透的低影响开发实践有潜力限制微塑料污染向下游的扩散。
