Plastic Gear in Korean Aquaculture as a Source of Bisphenol A in Coastal Marine Environments

Marine plastic pollution has traditionally been recognized for its physical impacts, including aesthetic degradation, ghost fishing, ingestion and entanglement of marine organisms, and the generation of microplastics. In recent years, however, plastic debris has also gained attention as a potential chemical pollution source due to the release of various additives incorporated into plastic products. In a previous screening analysis of marine plastic debris and newly manufactured plastic products, we found that polyvinyl chloride (PVC)-coated ropes used in oyster aquaculture contained exceptionally high concentrations of bisphenol A (BPA), reaching up to 101,000 ng/g. Based on the concentration differences between new products and weathered debris collected from coastal environments, the total amount of BPA potentially released from PVC-coated ropes used in Korean oyster farms was estimated to be approximately 140–194 kg. These findings suggest that aquaculture gear may represent a previously underappreciated source of chemical contamination in marine environments. In this study, we investigated the release behavior of BPA from PVC-coated aquaculture ropes under controlled laboratory conditions and evaluated the environmental distribution of BPA in marine sediments. Coated ropes were exposed to seawater at two temperatures (6 °C and 26 °C), representing winter and summer conditions, to assess seasonal variability in BPA release. The results showed rapid leaching of BPA into seawater, with substantially higher release rates at 26 °C than at 6 °C. On average, BPA concentrations in seawater at 26 °C were approximately two to three times higher than those observed at 6 °C over the same exposure period, indicating strong temperature dependence of BPA mobilization. In parallel, surface sediments (0–2 cm) were collected from oyster farming areas, urban coastal sites, and offshore reference locations. Sediment analysis revealed significantly higher BPA concentrations in aquaculture sites compared to urban and offshore areas. Overall, our findings demonstrate that PVC-coated ropes used in oyster aquaculture can act as a significant source of BPA to the marine environment, highlighting the need to consider aquaculture gear as a contributor to chemical pollution in coastal ecosystems.