Solving the Urban Plastic Soup

Urban plastic entry into rivers is a global problem but lacks empirical quantification in cities. This thesis quantifies plastic pollution in Amsterdam and explores its drivers to design targeted interventions. Amsterdam emits approximately 1.9 million plastic items annually, ranking it among the most polluted river systems. High-frequency monitoring across twenty locations explores the complex nature of the urban plastic soup. I developed a framework to standardize how researchers and policymakers can define hotspots and prioritize interventions. I identified the top ten most abundant plastics based on 10,000 monitored items, comprising 80% of all floating litter by count. Based on this top ten, seven interventions and mitigation strategies along the plastic life cycle were evaluated, advocating for upstream R-ladder measures over downstream cleanups and waste management. My thesis provides key insights for cities to transition from anecdotal evidence to a data-driven understanding of urban plastic dynamics.