Department of Earth and Atmospheric Sciences, Saint Louis University, St. Louis, Missouri, 63108, United States; WATER Institute, Saint Louis University, St. Louis, Missouri, 63103, United States.
Department of Earth and Atmospheric Sciences, Saint Louis University, St. Louis, Missouri, 63108, United States; WATER Institute, Saint Louis University, St. Louis, Missouri, 63103, United States.
Environ Pollut. 2022 Oct 15;311:119852. doi: 10.1016/j.envpol.2022.119852. Epub 2022 Aug 6.
Microplastics are emerging contaminants ubiquitously distributed in the environment, with rivers acting as their main mode of transport in surface freshwater systems. However, the relative importance of hydrologic processes and source-related variables for benthic microplastic distribution in river sediments is not well understood. We therefore sampled and characterized microplastics in river sediments across the Meramec River watershed (eastern Missouri, United States) and applied a hydrologic modeling approach to estimate the relative importance of river discharge, river sediment load, land cover, and point source pollution sites to understand how these environmental factors affect microplastic distribution in benthic sediments. We found that the best model for the Meramec River watershed includes both source-related variables (land cover and point sources) but excludes both hydrologic transport-related variables (discharge and sediment load). Prior work has drawn similar and dissimilar conclusions regarding the importance of anthropogenic versus hydrologic variables in microplastic distribution, though we acknowledge that comparisons are limited by methodological differences. Nevertheless, our findings highlight the complexity of microplastic pollution in freshwater systems. While generating a universal predictive model might be challenging to achieve, our study demonstrates the potential of using a modeling approach to determine the controlling factors for benthic microplastic distribution in fluvial systems.
微塑料是一种新兴的环境污染物，广泛分布于环境中，河流是其在地表淡水系统中迁移的主要载体。然而，水文学过程和与源相关的变量对河流沉积物中底栖微塑料分布的相对重要性还不太清楚。因此，我们在密西西比河流域（美国密苏里州东部）的河流沉积物中进行了采样和微塑料特征分析，并应用水文学模型方法来估计河流径流量、河流沉积物负荷、土地覆盖和点源污染对理解这些环境因素如何影响底栖沉积物中微塑料分布的相对重要性。我们发现，密西西比河流域的最佳模型同时包含了与源相关的变量（土地覆盖和点源），但排除了与水文学运输相关的变量（径流量和沉积物负荷）。尽管我们承认，由于方法上的差异，比较存在局限性，但先前的工作已经得出了关于人为因素与水文学变量在微塑料分布中的重要性的相似和不同的结论。然而，我们的研究结果突出了淡水系统中微塑料污染的复杂性。虽然生成一个普遍的预测模型可能具有挑战性，但我们的研究表明，使用建模方法来确定河流系统中底栖微塑料分布的控制因素是有潜力的。
