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 microg/L), whereas APEOs and APs contributed only small amounts to the overall APEM concentrations (0.10-0.92 and < or =0.1 microg/L, respectively) except where the effluent was infiltrated into soil (5.2 microg/L). In effluents, ibuprofen and its metabolites, TCPPs, and NBBS were detected regularly (<0.5 microg/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.

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The degradation pathway of nonylphenol ethoxyacetic acid (NP1EC) and the conditions favoring dicarboxylated alklyphenol ethoxyacetic acid (CAnP1EC; where n = the number of aliphatic carbon atoms) formation were studied in oxic microcosms constructed with organic carbon-poor soil from the Mesa soil aquifer treatment (SAT) facility (Arizona) and pristine organic carbon-rich sediments from Coyote Creek (California). Results suggest that the availability of dissolved oxygen determines the dominant biodegradation pathway; ether cleavage and the formation of NP is favored by oxic conditions, while alkyl chain oxidation and the formation of CAP1ECs is favored under microxic conditions. In the Mesa microcosms, para-NP1EC was transformed to para-nonylphenol (NP) before being rapidly transformed to nonyl alcohols via ipso-hydroxylation. In the Coyote Creek microcosms, large quantities of CAP1ECs were observed. Initially, CA8P1ECs were the dominant metabolites, but as biodegradation continued, CAP1ECs became the dominant metabolites. Compared to the CAsP1ECs, the number of CA6P1ECs peaks observed was small (< 6) even though their concentrations were high. Several novel metabolites, tentatively identified as 3-alkylchroman-4-carboxylic acids (with alkyl groups ranging from C2 to C5), were formed in the Coyote Creek microcosms. These metabolites are presumably formed from ortho-CAP1ECs by intramolecular ring closure.