Occurrence Characteristics and Risk Assessment of Microplastics in Surface Water of Dongting Lake Wetland during the Dry Season

As a key ecosystem in the land-water transition zone, microplastic pollution research in wetlands has long lagged behind other aquatic systems. This study focused on Dongting Lake, a typical wetland in the middle reaches of the Yangtze River, China. Surface water samples were collected during the dry season from eight sampling sites along the “Four Rivers and Three Outlets” inflow sections and the Chenglingji outflow section. Microplastics were analyzed for abundance, size, shape, color and polymer types through microscopic observation and FTIR. Multidimensional risk assessments were conducted using the pollution load index (PLI), polymer hazard index (PHI), and potential ecological risk index (RI). Results showed that microplastic abundance in the Dongting Lake wetland ranged from 4 to 28.5n/L, representing a moderate pollution level compared to other domestic wetlands. The microplastics were predominantly transparent (66.9%) fragments and fibers (84.8%), with sizes mainly below 200μm (83.9%). The dominant polymers were polyethylene terephthalate (PET, 27.7%), polypropylene (PP, 16.5%), polyvinyl chloride (PVC, 14.9%), and polyethylene (PE, 11.2%). The results of the risk assessment showed that environmental risks were characterized by “low abundance and load, but high toxicity and risk”. Polyurethane (PU), PVC, acrylonitrile butadiene styrene (ABS), polycarbonate (PC) and other highly toxic polymers were detected in 62.5% of the sampling points, and their risk indices reached high-risk or extremely high-risk levels. The BRIEF REPORT is available for this paper at http://www.ykcs.ac.cn/en/article/doi/10.15898/j.ykcs.202504030078.