Department of Biology, McGill University, Montréal, QC, Canada; Redpath Museum, McGill University, Montréal, QC, Canada; Groupe de Recherche Interuniversitaire en Limnologie (GRIL), Montréal, QC, Canada.
Department of Biology, McGill University, Montréal, QC, Canada; Groupe de Recherche Interuniversitaire en Limnologie (GRIL), Montréal, QC, Canada.
Environ Pollut. 2020 May;260:113994. doi: 10.1016/j.envpol.2020.113994. Epub 2020 Jan 14.
Microplastics are pervasive pollutants in fresh waters, but their distribution, abundance, and diversity in fluvial environments remain poorly documented. Previous research indicated that large polyethylene microbeads were abundant in the freshwater sediments of the St. Lawrence River. Here we extend this work by quantifying the abundance of a broad range of sizes and types of microplastics in sediments and surface water samples, and we relate these metrics to environmental variables. We sampled 21 sites for sediments that spanned a land use gradient, and 10 surface water stations above and below wastewater effluent sites, along the fluvial corridor of the St. Lawrence River between Montreal and Quebec City from July to August 2017. Microplastics were removed from sediments using an oil extraction protocol and enumerated under fluorescent microscopy. We tested predictions that environmental filters and known point sources affect microplastic concentrations in the river. The mean concentration of microplastics across all sediment sampling sites was 832 (±150 SE) plastics per kg dry weight (range 65-7562 plastics per kg dry weight), which is among the highest recorded (in the top 25%) for the world's freshwater and marine systems. Microplastic concentrations in the sediments were significantly related to a suite of environmental variables including land use and sediment particle characteristics. Particle characteristics, proximity to point sources (urban land use), and environmental filters (sediment compositional variables, % organic carbon, % inorganic carbon and distance from shore) each explained a significant fraction of variation in the microplastic composition in the sediment, with environmental filters having the greatest influence. We present a protocol that could be used to efficiently and accurately detect a broad range of microplastics until a standardized protocol is established for large-scale monitoring.
微塑料是淡水中普遍存在的污染物，但它们在河流环境中的分布、丰度和多样性仍记录甚少。先前的研究表明，圣劳伦斯河的淡水沉积物中大量存在大尺寸的聚乙烯微珠。在此，我们通过量化沉积物和地表水样本中广泛大小和类型的微塑料的丰度，并将这些指标与环境变量相关联，扩展了这项工作。我们在 2017 年 7 月至 8 月期间，沿着圣劳伦斯河从蒙特利尔到魁北克城的河流走廊，在跨越土地利用梯度的 21 个沉积物采样点和 10 个地表水站（位于废水排放口上方和下方）进行了采样。使用油提取方案从沉积物中去除微塑料，并在荧光显微镜下对其进行计数。我们测试了环境过滤器和已知的点源影响河流中微塑料浓度的预测。所有沉积物采样点的微塑料平均浓度为 832（±150 SE）个/千克干重（范围为 65-7562 个/千克干重），这是世界上淡水和海洋系统中记录最高的（前 25%）之一。沉积物中微塑料的浓度与一系列环境变量显著相关，包括土地利用和沉积物颗粒特征。颗粒特征、靠近点源（城市土地利用）以及环境过滤器（沉积物组成变量、有机碳百分比、无机碳百分比和离岸距离）都对沉积物中微塑料组成的变化有显著影响，其中环境过滤器的影响最大。我们提出了一种方案，可以有效地和准确地检测广泛的微塑料，直到建立用于大规模监测的标准化方案。
