Distribution and seasonal occurrence of UV filters in rivers and wastewater treatment plants in Korea.

The occurrence and distribution of eight UV filters benzophenone (BP), benzophenone-3 (BP-3), ethylhexyl methoxy cinnamate (EHMC), 4-methylbenzylidene camphor (4-MBC), 2-ethylhexyl 4-dimethylaminobenzoate (OD-PABA), 2-ethylhexyl salicylate (EHS), isoamyl benzoate, and benzyl cinnamate in eleven sites among three rivers, five sewage treatment plants (STPs), and four wastewater treatment plants (WWTPs) located in different parts of Korea was investigated. The total concentrations of UV filters in the three sampled seasons were 62.9-412 ng L(-1) (river), 417-5055 ng L(-1) (STP influent), 108-2201 ng L(-1) (STP effluent), 122-4154 ng L(-1) (WWTP influent), and 120-849 ng L(-1) (WWTP effluent). The concentration of the target pollutants in the influent of the treatment systems was directly proportional to the resident population density. A seasonal increase of >27% was observed in the total concentration of the UV filters in the rivers and influents of the treatment plants (TPs) during summer. BP, BP-3, EHMC, 4-MBC, and EHS were the most dominant, showing a distinct distribution pattern that was dependent on the effectiveness of the treatment process and properties of each compound. The concentrations of the UV filters were higher in the TPs influents than in the rivers, and the most dominant UV filters in the rivers were those with low removal rate. Although biological treatment processes favored the removal of the UV filter compounds in the TPs, complete removal was not achieved before discharge into the rivers.