Plastic pollution in marine coastal areas: Quantifying leakage and evaluating management responses

Assessment of plastic waste leakage into the environment in marine-coastal areas represents a significant global environmental challenge. This study quantified plastic leakage in two representative municipalities of Colombia's Caribbean (Puerto Colombia) and Pacific (Tumaco) regions, using the Waste Flow Diagram (WFD) methodology complemented by marine litter monitoring in coastal ecosystems. Results highlighted differences in plastic waste management and final disposal between the regions, with leakage rates into aquatic systems ranging from 1.5 to 9 kg/person/year. Marine litter characterization revealed a predominance of plastic materials (77.83 % in Tumaco and 93.85 % in Puerto Colombia), mainly single-use items, whose accumulation varies according to specific geographic, operational, and socioeconomic factors of each region. The analysis identified critical deficiencies in waste management systems, including insufficient collection coverage and infrastructure limitations, which significantly contribute to aquatic ecosystem contamination. Spatial patterns of plastic waste accumulation exhibited significant variation, with concentrations ranging from 0.16 to 4.24 items/m² on Caribbean beaches and 0.36 to 1.69 items/m² in the Pacific, reflecting the influence of coastal dynamics, tourism activities, and local disposal practices. The application of the WFD tool allowed the identification of critical intervention points and the establishment of a baseline for developing public policies aimed at reducing plastic pollution. This research provides essential scientific evidence for the development of integrated plastic waste management strategies in marine-coastal zones, emphasizing the need for region-specific solutions to effectively conserve these strategic ecosystems.