Occurrence and ecological risks of microplastics and bisphenol A in a coastal receiving environment affected by wastewater from a large-scale plastic production enterprise.

Plastic production enterprises are significant sources of microplastics (MPs) and bisphenol A (BPA), but the environmental impacts of their wastewater remain unclear. This study investigated the receiving environment of a large-scale plastic production enterprise whose wastewater discharges into a coastal inflow river and ultimately flows into the bay. MP concentrations in downstream river water and sediments ranged from 1001 to 2514 items/L and 3055-6355 items/kg, respectively, increasing by 413.21% and 380.69% compared with upstream areas. In the outlet effluent, polyethylene was dominant (35.75%), followed by polypropylene (25.12%) and polyethylene terephthalate (21.65%). Polyethylene terephthalate tended to deposit in sediments, while PE migrated over long distances and dominated downstream river and bay samples. The molecular weight of MPs showed an increase of 10.19%-28.29% in downstream areas, which suggests the input of less-aged MPs from the plastic production enterprise. As BPA carriers, MPs contained BPA at concentrations 2-12 times higher than background concentration, and BPA release during MP fragmentation may pose a potential threat. To evaluate ecological risks, toxicity data for MPs in freshwater, seawater, freshwater sediment, and marine sediment were compiled separately, and species sensitivity distribution and risk quotient (RQ) methods were applied to each compartment. For MPs, RQ values were 10.52-119.71 in freshwater, 4.70-17.38 in seawater, 0.45-4.64 in freshwater sediment, and 5.57-19.13 in marine sediment, indicating generally high ecological risk. Overall, plastic industry effluent greatly modified pollutant composition, transport behavior, and ecological risks across the coastal environment.