Chinese Journal of Environmental Engineering•2026•DOI: 10.12030/j.cjee.202509067
Marine litter poses a significant threat to coastal ecosystems globally, necessitating a comprehensive understanding of its multi-compartment distribution and driving mechanisms for effective management. This study investigated the occurrence, composition, and sources of beach, sea surface, and seafloor litter in the northeastern Daya Bay, a semi-enclosed bay, during August–October 2024. Sampling included 11 beach transects, 6 surface transects, and 25 seafloor transects. Results showed that the mean density of large and very large beach litter was 4.41×10^5 items·km−2, while medium beach litter reached 5.39×10^6 items·km−2. Surface litter densities were 5.82×10^2 and 9.90×10^3 items·km−2 for large/very large and medium fractions, respectively. Seafloor litter averaged 5.20×10^3 items·km−2. Plastics dominated all compartments, accounting for 74.0% (beach), 96.0% (surface), and 78.8% (seafloor) of total litter. Source apportionment using NOWPAP methodology indicated that beach and surface litter primarily originated from coastal recreational activities, whereas seafloor litter was mainly derived from shipping and fishing. Beach quality assessment revealed that 63.6% of beaches were moderately clean or better (grade II–IV), and 90.9% were moderately safe or better (grade I–III). Hotspots included tourism beaches, tidal gyre areas, coral reef zones, and fishing grounds. The study underscores the need for targeted management, including improved waste collection on tourist beaches, dynamic cleaning protocols, and port reception facilities for fishing waste.
Environmental Chemistry•2026•DOI: 10.7524/j.issn.0254-6108.2025030501
Coastal areas serve as critical ecological interfaces for the migration of terrestrial microplastics (MPs) into the ocean, and characterizing their pollution is essential for integrated coastal management. This study investigated the occurrence, sources, and ecological risks of MPs in surface waters of nearshore areas and river estuaries around Hainan Island, a typical tropical tourist island. MPs abundance ranged from 316.67 to 1300 n·m−3 in seawater and from 400 to 5416.67 n·m−3 in river water. In seawater, the dominant polymer was polyethylene terephthalate, with fibers being the predominant shape, size class 500–1000 μm, and white/transparent color. In river water, polypropylene-ethylene copolymer dominated, also as fibers, but with size class 100–500 μm and white/transparent color. Seawater MP abundance showed a significant positive correlation with tourist numbers, and distribution across functional areas followed: tourism areas > natural areas > aquaculture areas > residential areas. Multiple correspondence analysis identified household plastic waste, laundry wastewater, aquaculture, and fishery products as primary sources of seawater MPs. Principal component analysis indicated homologous characteristics between seawater and river MPs, suggesting rivers are a major pathway for terrestrial MP transport to coastal zones. Ecological risk assessment revealed low pollution loads, with potential ecological risks moderate for seawater and medium-low for river water. Notably, 15% of seawater sampling sites exhibited polymer risk level Ⅳ, primarily driven by polyacrylonitrile's high biological toxicity. These findings provide a scientific basis for developing MP pollution control strategies in Hainan Island.