Microplastic pollution and ecological risk in estuaries and coastal areas: A case study at Han River estuary, Da Nang city, Vietnam

Microplastics (MPs) pollution has been identified as a significant environmental concern in various ecosystems, including estuarine and coastal waters. In this study, surface and column water samples from the Han River (Vietnam) were collected during the rainy season of 2023 and the dry season of 2024 and analyzed. Microplastic characteristics were determined based on quantity, shape, size, color, polymer composition, and Pollution Load Index (PLI). Microplastics were detected at all sampling locations, with marked spatial and seasonal variability. Total MPs abundance in the dry season was consistently lower than in the rainy season. In the rainy season, MPs density in column water exceeded that in surface water, whereas the reverse pattern was observed in the dry season. Microfragments and microfibers of smaller size classes predominated. White was the most common color, followed by blue, green, red, and other colors. The number of polymer types in the rainy season was 22 and decreased to 5–6 in the dry season. Polyethylene terephthalate (PET) accounted for the highest proportion of all samples. The calculated PLI value (1.74) was classified as “Hazard Level I,” indicating a low pollution load; however, the potential environmental risks posed by microplastics remain a concern. Clinical trial number: not applicable