Accumulation of Microplastic Particles in Terrestrial Ecosystems.

Land-application of wastewater treatment sludge, or biosolids, represents an economically viable, environmentally sound, and socially responsible way to tighten regional nutrient cycles and increase soil organic matter while meeting crop nutrient requirements. However, land-applied biosolids may cause soil and water quality issues arising from accumulation of microplastic particles and nanoparticles contained in the biosolids. Microplastics and nanoparticles originating from cosmetic and health care products usually end up in our household wastewater, which is treated in a wastewater treatment plant. There, these particles are removed from water and accumulate in biosolids. While much research has been done to quantify the amount of these contaminants in wastewater treatment effluent waters, it is largely unknown whether long-term application of biosolids leads to buildup and movement of microplastics and nanoparticles in soil. The objectives of this research are (1) to quantify the presence of microplastics and silver nanoparticles in biosolids and agricultural soil samples, (2) determine whether 20 years of biosolids application to agricultural soils has led to accumulation of these particles, and (3) elucidate fate and transport of microplastics and silver nanoparticles in soils. We used microscopic techniques to identify and quantify microplastic particles and silver nanoparticles in biosolids and soils.