Microplastics in Different Coastal Environmental Matrices and Potential Ecological Risks

Microplastic pollution is an emerging environmental concern in coastal ecosystems, particularly in developing regions. However, research remains compartmentalized, limiting an integrated understanding of microplastic distribution, transport dynamics, and ecological risks across interconnected environmental matrices. In this study, a multi-matrix assessment was conducted to evaluate microplastic abundance, characteristics, and associated ecological risks. A total of 93 microplastic particles were identified, with the mangrove site exhibiting the highest concentration (200 items/kg), while the seagrass bed and estuary showed the lowest concentration (3.33 items/kg). The dominant microplastic type was primarily fiber (55.91%), with most particles ranging from 0.1 to 1 mm, and polypropylene (66.67%) was the predominant polymer type, reflecting the widespread contribution from plastic packaging and fishing gear. Significant correlations were observed between microplastic abundance and contamination factor (CF), pollution load index (PLI), and potential ecological risk index (PERI), whereas the polymer hazard index (PHI) showed no significant relationship due to its dependence on polymer composition. Non-metric multidimensional scaling (NMDS) revealed distinct distribution patterns of microplastic shape and polymer type across matrices. Overall, microplastic distribution across environmental matrices is driven by heterogeneous sources and transport pathways, with mangrove sediments enhancing retention, underscoring the need to elucidate seaward and landward source contribution and coastal fluxes.