Jeq50248 1078..1087

Recently, our attention has focused on the low level detection of many antibiotics, pharmaceuticals, and other organic chemicals in water resources. The limited studies available suggest that urban or rural streams receiving wastewater effluent are more susceptible to contamination. The purpose of this study was to evaluate the occurrence of antibiotics, pharmaceuticals, and other organic chemicals at 18 sites on seven selected streams in Arkansas, USA, during March, April, and August 2004. Water samples were collected upstream and downstream from the influence of effluent discharges in northwestern Arkansas and at one site on a relatively undeveloped stream in northcentral Arkansas. At least one antibiotic, pharmaceutical, or other organic chemical was detected at all sites, except at Spavinaw Creek near Mayesville, Arkansas. The greatest number of detections was observed at Mud Creek downstream from an effluent discharge, including 31 pharmaceuticals and other organic chemicals. The detection of these chemicals occurred in higher frequency at sites downstream from effluent discharges compared to those sites upstream from effluent discharges; total chemical concentration was also greater downstream. Wastewater effluent discharge increased the concentrations of detergent metabolites, fire retardants, fragrances and flavors, and steroids in these streams. Antibiotics and associated degradation products were only found at two streams downstream from effluent discharges. Overall, 42 of the 108 chemicals targeted in this study were found in water samples from at least one site, and the most frequently detected organic chemicals included caffeine, phenol, para-cresol, and acetyl hexamethyl tetrahydro naphthalene (AHTN). AWIDE VARIETY OF CHEMICALS can enter streams through municipal wastewater treatment plant (WWTP) effluent discharges, including prescription and nonprescription drugs, hormones, antimicrobial agents, pesticides, disinfectants, and fragrances. Although many of these synthetic organic chemicals were developed and are used for beneficial purposes, the occurrence of these chemicals in surface and ground water resources has prompted the recognition of potential ecological and human health concerns. For example, the antimicrobial agent triclosan that is often found in WWTP effluents (Lindstrom et al., 2002) may affect algal growth and community structure (Wilson et al., 2003; White et al., 2005) and is suspected of increasing antibiotic resistance in multiple bacterial lineages (McMurry et al., 1998). Reiss et al. (2002) concluded that the potential exists for triclosan to affect aquatic organisms downstream from effluent discharges, especially during low flow periods when dilution is minimal. In reality, little is known about the potential adverse effects from chronic environmental exposure to these individual chemicals and chemical mixtures at very low doses on aquatic biota, other terrestrial animals, and also humans. Just recently, analytical methods have been developed that are capable of detecting these chemicals at very low levels found in the environment (Hirsch et al., 1998; Lindsey et al., 2001; Cahill et al., 2004), particularly in streams and ground waters (e.g., see Kolpin et al., 2002; Barnes et al., 2004; Derksen et al., 2004). The limited studies available indicate that urban or rural streams receiving effluent discharges from municipal WWTPs or animal feeding operations are at greatest risk of contamination from these chemicals. Although limited data are available, it appears that the occurrence of these organic wastewater compounds (OWCs) and other organic chemicals was widely prevalent in surface waters and that an increasing number of chemicals are being detected (Ternes, 1998;Kolpin et al., 2002;Derksen et al., 2004; Sprague and Battaglin, 2005). The purpose of this study was to provide a reconnaissance of the occurrence of antibiotics, pharmaceuticals, and other organic chemicals of emerging concern in selected streams in northwestern and north-central Arkansas. The importance of this survey study was to provide an inventory of pharmaceuticals and other organic chemicals that may be found in these streams so that more detailed studies can be conducted on the transport and fate of these chemicals in aquatic environments. MATERIALS AND METHODS Water samples were collected in March, April, and August 2004 from 18 sites on eight different streams in northwestern and north-central Arkansas (Fig. 1, Table 1). The sampling site (Site 3) and stream selected in north-central Arkansas was North Sylamore Creek near Fifty-Six, Arkansas, representing a sampling site that drains a relatively undeveloped, mostly forested catchment. North Sylamore Creek is part of the U.S. Geological Survey Hydrologic Benchmark Network which includes sites across the nation where long-term measurements of stream discharge and water-quality data are collected. The other sampling sites and streams in northwestern Arkansas were targeted because these streams receive B.E. Haggard, Biological and Agricultural Engineering Department, University of Arkansas, 203 Engineering Hall, Fayetteville, AR 72701; formerly USDA-ARS, Poultry Production and Product Safety Research Unit, Fayetteville, AR. J.M. Galloway and W.R. Green, U.S. Geological Survey Arkansas Water Science Center, 401 Hardin Road, Little Rock, AR 72211. M.T. Meyer, U.S. Geological Survey Organic Chemistry Research Laboratory, 4821 Quail Crest Place, Lawrence, KS 66049. Mention of any trade name, proprietary product, or specific equipment does not constitute a guarantee or warranty by the USDA and does not imply its approval to the exclusion of other products that may be suitable. Received 22 June 2005. *Corresponding author