Collaborative Research: Terrestrial microplastic pollution: understudied sources, source tracking, and citizen science

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Microplastics are plastic particles smaller than 5 millimeters. Microplastics are found in aquatic and terrestrial environments across the globe. Past research has established that stormwater, wastewater effluent, and runoff from urban areas and agricultural fields can carry microplastics into rivers, lakes, and streams. However, the details of how microplastics move in the environment is largely unknown. The goal of this research is to address this gap in our knowledge by measuring plastics in urban, suburban, and rural areas. These results will determine the influence of land use on microplastics entering into aquatic systems in the US. Results from this study will be used to assess the impact of legislative bans on microplastics in consumer products. The research will be facilitated by using citizen science groups trained and engaged to measure plastic levels in water in their communities. The impact of the citizen science efforts will increase the scientific literacy of the engaged groups, and results will be disseminated to the public, stakeholders, and regulatory agencies tasked with managing microplastics wastes. Although research has shown that over 12.7 million metric tons of microplastic waste enters the ocean on an annual basis, the relative importance of microplastics from different terrestrial sources (e.g., land application of biosolids, urban stormwater) is poorly understood. A multipronged study of microplastic transport in the environment involving field surveys and controlled field studies will be performed to address this knowledge gap. The specific objectives are to quantify loading rates, particle morphology, and composition of microplastics for two under-reported terrestrial transport routes and evaluate microplastic source tracking techniques in freshwater across disparate geographies. To date, no study has evaluated source tracking consistently across geographies. To overcome these limitations of past research, polymer identification will be performed using various techniques including FT-IR and/or micro-FT-IR. The project team will leverage ongoing collaborations with citizen scientists to carry out the research. Scientifically defensible measurements of terrestrial and aquatic microplastics will be achieved through an extensive quality control program that includes the analysis of spiked and FT-IR evaluated samples. At the conclusion of this project, the project team will disseminate quantitative information to the scientific, stakeholder, and public communities on microplastics loading across diverse geographies that will allow assessment of the influence of microplastic usage bans and voluntary phase outs. This study represents one of the first to directly evaluate the flux of plastics from land application of biosolids and stormwater. Importantly, this work will advance science by evaluating source tracking techniques across geographies in freshwater systems, which has not been performed previously using consistent methods.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.