Plastic pathways and intervention strategies in urban water systems

Plastic pollution escalated into a global environmental problem, threatening human health, ecosystems, and sustainable development. Despite global, regional, and local mitigation efforts, plastic production is projected to double, exceeding waste management infrastructure growth. Understanding plastic pathways, analyzing impacts, and designing effective interventions in urban water systems necessitate a finer regional or local resolution than currently provided by global and national studies. Here we quantified the mass flows of ten most abundant plastic items throughout their life cycle and proposed interventions for the Amsterdam urban water system. We used a dataset of 9968 floating (plastic) items at twenty diverse locations, with the top ten items comprising 80% of the total items (39.3% of the total mass). Despite representing less than 0.01% of plastic use in Amsterdam, end-of-life littering and spills cause disproportionate environmental harm relative to their abundance. Systematic interventions are required in Amsterdam to reduce the annual loss of 16.0 (2.9-34.7) metric tons of plastic into the IJ River. We defined seven interventions to reduce plastic consumption and contribute to a closed-loop plastic system. Successful implementation demands a transition with changes in legislation (regarding production, item design, and waste management), decision-making, and consumer behavior. We prioritize intervention methods according to the waste hierarchy, emphasizing waste prevention over impact mitigation. Decision-support tools including these interventions can guide authorities to achieve (inter)national reduction and circularity goals. Ultimately, this paper aims to provide decision-makers with actionable insights, accelerating the transition to a circular and less polluting plastic economy and sustainable, plastic-free environments.