Microplastics fingerprinting at the watershed scale: from sources to receivers

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Plastics pollution is a global and growing environmental hazard with potentially far-reaching consequences for food webs, biodiversity, ecosystem services and human well-being. Of particular concern are microplastics because their small sizes enhance their long-range transport, toxicity to biota, and capacity to sorb and leach contaminants, including organic pollutants and toxic metals. We propose to implement a holistic data acquisition and modeling strategy that will link the sources, transport, fate and exposure risks of microplastics at the scale of entire watersheds. In addition to established spectroscopic and imaging techniques, we will explore novel biosensors and microwave sensing for the rapid screening and typing of microplastics in environmental samples. We will improve the processing of large analytical datasets on microplastics assemblages and develop standardized workflows for the sampling, sample preparation, screening, analysis, data processing and data management of microplastics. These workflows will be applied to characterize the entry pathways to, and transport along, the river network, identify (bio)degradation proxies, quantify accumulation in reservoirs and on riverbanks, and estimate the export of microplastics to receiving lakes. Past microplastics pollution will be reconstructed from dated sediment cores while the analysis of microplastics loading and transport rates under variable hydrometeorological conditions will help forecast the impacts of more extreme precipitation events in the future. Our growing database will be integrated into a mass balance modeling platform that will enable extensive scenario testing, including the response of microplastics emissions and loadings to hypothetical source reduction measures. The scenario results, together with cost-benefit analyses and knowledge exchanges with stakeholders, will contribute to identifying policy instruments and governance approaches that can effectively protect freshwater ecosystems and drinking water sources from microplastics pollution.