Occurrence characteristics and multidimensional ecological risk assessment of microplastics in the Pearl River Estuary

Microplastics (MPs) have attracted increasing concern because they pose notable ecological risks and seriously endanger human health. Estuaries, which serve as transition zones between rivers and oceans, play an important role in MP transport. This study investigated the abundances, polymer types, morphological characteristics, and ecological risk levels of MPs in a representative estuary region, namely the Pearl River Estuary in Southern China. The results revealed MP pollution in the estuary, with average abundances of 1116 n/m 3 and 2702 n/kg in water and sediments, respectively. The highest abundance was found in fish intestine, attributable to the selective ingestion and retention of MPs within the digestive tract. The detected MPs were dominated by cellophane and polyethylene terephthalate. The particles were mainly filamentous and fibrous, transparent or blue, and <1 mm in size. The ecological risk of MP pollution in the Pearl River Estuary was assessed using the pollution-load index, risk quotient, and probabilistic methods. The results demonstrated high environmental risk levels at individual sampling points in the Pearl River Estuary, highlighting the need for targeted mitigation strategies to prevent further ecological deterioration. Overall, the present results provide theoretical support for the environmental management of MPs. They also provide fundamental data and a scientific basis for the prevention and control of new pollutants and the construction of a healthy estuarine environment.