Development of diffusive gradients in thin film technique for seasonal monitoring of benzophenone-type UV filters in coastal waters

Benzophenone(BP)-type UV filters are continuously released into various aquatic environments via the effluent discharge of wastewater treatment plants (WWTPs) and recreational activities in coastal beaches. In this study, we developed a robust and reliable sampling approach, diffusive gradients in thin-films (DGT), for seasonal monitoring of six BP derivatives in coastal waters to investigate their occurrence and environmental risk. The binding capacities of both XAD-2 and HLB gels for test BPs were over 252 mu g with no significant deterioration in marine environment, suggesting that theoretically, DGT is capable of sampling for at least 3 months effectively. The diffusion coefficients of BPs in freshwater and seawater were determined for the first time. The sampling performance showed no dependence on environmental conditions including pH (4.0-8.5), ionic strength (0.0001-0.5 M) and dissolved organic matter (0-20 mg L-1). The developed DGT samplers were successfully applied in a river estuary linked to a WWTP and a bathing beach at different periods of one year. Results showed that the concentrations of BPs in the coastal waters were dependent on seasonal variation. The highest level in summer and the ecological risk should be considered based on the risk quotient values. These results demon-strated that the present DGT method is suitable for measuring, characterization, and risk assessment of BPs in freshwater and marine environment.

Automated summary

This study developed a robust sampling method, DGT, to monitor six BP derivatives in coastal waters and assess their environmental risk. The results showed that the concentrations of BPs in coastal waters varied with seasons, with the highest levels in summer, highlighting the importance of considering ecological risks.