Occurrence and Fate of and Naproxen in Surface Waters

Abstract

Although various single-concentration measurements of pharmaceuticals are available in the literature, detailed information on the variation over time of the concentration and the load in wastewater effluents and rivers and on the fate of these compounds in the aquatic environment are lacking. We measured the concentrations of six pharma- ceuticals, carbamazepine, clofibric acid, diclofenac, ibuprofen, ketoprofen, and naproxen, in the effluents of three wastewater treatment plants (WWTPs), in two rivers and in the water column of Lake Greifensee (Switzerland) over a time period of three months. In WWTP effluents, the concentrations reached 0.95 µg/L for carbamazepine, 0.06 µg/L for clofibric acid, 0.99 µg/L for diclofenac, 1.3 µg/L for ibuprofen, 0.18 µg/L for ketoprofen, and 2.6 µg/L for naproxen. The relative importance in terms of loads was carbamazepine, followed by diclofenac, naproxen, ibuprofen, clofibric acid, and ketoprofen. An overall removal rate of all these pharmaceuticals was estimated in surface waters, under real-world conditions (in a lake), using field measurements and modeling. Carbamazepine and clofibric acid were fairly persistent. Phototransformation was identified as the main elimination process of diclofenac in the lake water during the study period. With a relatively high sorption coefficient to particles, ibuprofen might be eliminated by sedimentation. For ketoprofen and naproxen, biodegradation and phototransformation might be elimination processes. For the first time, quantitative data regarding removal rates were determined in surface waters under real-world conditions. All these findings are important data for a risk assessment of these compounds in surface waters. Introduction Although pharmaceuticals are used in large quantities in modern society, their potential to reach surface waters and theirimpactontheenvironmenthavereceived little attention during the last three decades.However,since the 1980s,some investigations have been carried out on the occurrence and fate of pharmaceuticals in the environment (1).Themajority of these field investigations focused on the determination of * Corresponding author. Phone: +41-1-823-5460. Fax: +41-1- 823-5471. E-mail: stephan.mueller@eawag.ch. 10.1021/es025834r CCC: $25.00 © 2003 American Chemical Society Published on Web 02/06/2003 concentration