Occurrence and fate of pharmaceuticals and alkylphenol ethoxylate metabolites in an effluent-dominated river and wetland

The occurrence of pharmaceuticals, nonylphenol ethoxylate metabolites, and other wastewater-derived contaminants in surface waters is a potential environmental concern, especially since the discovery of contaminants with endocrine-disrupting properties. The present study investigated the discharge of emerging contaminants into the Santa Ana River (CA, USA) and their attenuation during river transport and passage through a constructed wetland. Contaminants studied included pharmaceuticals (gemfibrozil, ibuprofen, naproxen, ketoprofen, and carbamazepine) and their metabolites, hormones, the metabolites of alkylphenol polyethoxylates (APEMs), N-butyl benzenesulfonamide (NBBS), and chlorinated tris-propylphosphates (TCPPs). The APEMs included alkylphenols (APs), short-chain AP polyethoxylates (APEOs), AP polyethoxycarboxylates (APECs), and carboxylated APECs (CAPECs). In wastewater treatment plant effluent, APECs and CAPECs represented the dominant APEM fraction (1.8-18.7 mug/L), whereas APEOs and APs contributed only small amounts to the overall APEM concentrations (0.10-0.92 and less than or equal to 0.1 mug/L, respectively) except where the effluent was infiltrated into soil (5.2 mug/L). In effluents, ibuprofen and its metabolites TCPPs, and NBBS were detected regularly (<0.5 mug/L), and the other pharmaceuticals were detected occasionally. Transport in the Santa Ana River for 11 km resulted in the significant attenuation of all contaminants, from 67% for gemfibrozil to 100% for others. Wetland treatment (residence time, 2-4 d) resulted in partial removal of ibuprofen, gemfibrozil, and TCPPs and transformed APEOs to APECs.