Occurrence, distribution, source identification, and risk assessment of organophosphate esters in the coastal waters of Beibu Gulf, South China Sea: Impacts of riverine discharge and fishery

As emerging pollutants, the environmental geochemistry of organophosphate esters (OPEs) in the coastal zone with multiple functional areas are still less recognized. This study investigated spatiotemporal distribution, sources and risks of 11 widely used OPEs in surface waters from seagoing rivers and multiple coastal functional areas of the Beibu Gulf. The results indicated that significantly higher n-ary sumation 11OPEs (total concentrations of 11 OPEs, ng/L) occurred in summer (34.2-1227) than in winter (20.6-840), as a result of the high emission caused by climate reasons. In general, higher n-ary sumation 11OPEs occurred in rivers (41.2-1227) than in the coast (34.2-809) in summer, especially in the urban rivers, while in winter, higher n-ary sumation 11OPEs occurred in the coast (23.4-840 vs 20.6-319 in rivers) because of obviously higher n-ary sumation 11OPEs in marine fishery areas (99-840). Source identification revealed that fishery activity, especially fishing vessels, and urban rivers were the main sources of OPEs in the Beibu Gulf. For the individual OPE, only tri-nbutyl phosphate (TNBP) may have ecological risks to aquatic organisms in a few sites, but if considering the additive effects, the OPEs mixtures would pose a high risk to algae and low to medium threats to crustaceans and fish.

Automated summary

This study investigated the spatiotemporal distribution, sources, and risks of organophosphate esters (OPEs) in the coastal zone of the Beibu Gulf. The results showed higher concentrations of OPEs in summer compared to winter, with rivers having higher concentrations than the coast. Fishing activities and urban rivers were identified as the main sources of OPEs in the Beibu Gulf. While individual OPEs may pose ecological risks to aquatic organisms, mixtures of OPEs could have high risks to algae and low to medium threats to crustaceans and fish.