Occurrence and source analysis of selected antidepressants and their metabolites in municipal wastewater and receiving surface water

Abstract

Seven commonly utilized antidepressants (amitriptyline, fluoxetine, sertraline, citalopram, paroxetine, venlafaxine, and bupropion) and three of their metabolites were detected in four wastewater treatment plants (WWTPs) and corresponding receiving waters including the mainstream and three of the tributaries of Huangpu River, Shanghai. The concentration levels of selected antidepressants in wastewater and receiving water were both at ng L⁻¹ level, but those antidepressants that were found in wastewater were typically in a range of one and even two orders of magnitude higher than those that were present in the receiving water except for the concentration levels of paroxetine, norfluoxetine, and nortriptyline. Venlafaxine and its metabolite O-desmethylvenlafaxine were the primary compounds (reaching up to 132.04 and 173.68 ng L⁻¹ as well as 3.03 and 4.53 ng L⁻¹ in wastewater and receiving water, respectively). Based on the mass loadings of selected antidepressants in four WWTPs, the mass loading of sertraline in effluent for this study was at the highest level when compared to other countries. The important finding was that the sampling sites H11 and H13 were much more likely to be polluted by side-pollution sources (the accumulation areas of Grade A of Class-three hospitals and pharmaceutical factories) than point pollution sources (WWTP 1 and WWTP2) through analysis of Spearman correlation. The results have shown that the RQs for these antidepressants were less than 0.1 except for the RQ of venlafaxine in an effluent for mollusks, which was less than 1. This indicated that the concentration levels of antidepressants would not pose a high risk for aquatic organisms, but sustained attention should still be paid.