Microplastic pollution and ecological risk assessment in an estuarine environment: The Dongshan Bay of China

Microplastic (MP) pollution has spurred a wide range of concerns due to its ubiquity and potential hazards to humans and ecosystems, yet studies on MP abundance, distribution, and ecological impacts on the small-scale local estuarine systems are insufficient. We conducted the first study of MP pollution in surface water of Dongshan Bay in southern China. A total of six water samples were collected using a Manta trawl (length = 3 m, width = 1 m, height = 0.6 m, and mesh size = ∼330 μm). The abundance, type, shape, color, and size, were measured using light microscopy and micro-Raman spectroscopy. Our results showed that MPs spanned from 0.23 to 4.01 particles m-3 with an average of 1.66 particles m-3. 75% of the MPs were PP, PE, and PS that may be explained by the widespread application of PE, PP, and PS foam in local fishing and aquaculture within the bay. Foam, white, and 1.0-2.5 mm were dominant shape, color, and size of MPs, respectively. Both indices of MPs-induced risk (Hestuary = 13.7) and pollution load (PLIestuary = 14.2) yielded a Hazard Level II for MPs pollution in the Dongshan Bay. The potential ecological risk from combined MPs polymers (RIestuary = 21.5) ended up at a minor risk. Our findings established the first set of baseline data on MPs pollution in Dongshan Bay and provided preliminary quantitative measures on the scale of ecological risk, which would improve the understanding of MP fate, transport, and ecological impacts in the estuarine environment.