Quantifying Major Sources of Atmospheric Microplastic Emissions in Michigan

Microplastics (MPs) have gained increasing attention as an environmental pollutant due to their ubiquity in the environment, including the atmosphere. MPs are emitted from several major processes on Earth’s surface to the atmosphere, where they may be subject to long-range transport. In this study, we build a bottom-up atmospheric MP emissions inventory for the state of Michigan. We consider several potential major sources, including non-exhaust vehicle emissions, fibrous microplastic (FMP) shedding from synthetic textiles, and resuspension of MPs in agricultural soil dust from fertilizers/plasticulture and lake spray aerosols from the Great Lakes. High-resolution (1 km) spatial emissions are quantified using state-, province-, national-, and global-level data sets to determine the relative importance of each major source. We estimate that mass emissions of MPs to the atmosphere in the Michigan region are primarily derived from traffic (74.7%), textiles (25.2%), and agricultural soil dust (0.1%). MP resuspensions due to lake spray aerosols were found to be a negligible source, yet large uncertainties remain regarding emission factors in freshwater systems. Our methodology and results provide a framework for future work in other locations to evaluate regional atmospheric MP emissions.