title: Urban contribution of pharmaceuticals and other organic wastewater contaminants to streams during differing flow conditions.
abstract: During 2001, 76 water samples were collected upstream and downstream of select towns and cities in Iowa during high-, normal- and low-flow conditions to determine the contribution of urban centers to concentrations of pharmaceuticals and other organic wastewater contaminants (OWCs) in streams under varying flow conditions. The towns ranged in population from approximately 2000 to 200,000. Overall, one or more OWCs were detected in 98.7% of the samples collected, with 62 of the 105 compounds being found. The most frequently detected compounds were metolachlor (pesticide), cholesterol (plant and animal sterol), caffeine (stimulant), beta-sitosterol (plant sterol) and 1,7-dimethylxanthine (caffeine degradate). The number of OWCs detected decreased as streamflow increased from low- (51 compounds detected) to normal- (28) to high-flow (24) conditions. Antibiotics and other prescription drugs were only frequently detected during low-flow conditions. During low-flow conditions, 15 compounds (out of the 23) and ten compound groups (out of 11) detected in more than 10% of the streams sampled had significantly greater concentrations in samples collected downstream than in those collected upstream of the urban centers. Conversely, no significant differences in the concentrations were found during high-flow conditions. Thus, the urban contribution of OWCs to streams became progressively muted as streamflow increased.
authors.affiliation: U.S. Geological Survey, 400 S. Clinton Street, Iowa City, IA 52244, USA. dwkolpin@usgs.gov
authors.forename: Dana W
authors.initials: DW
authors.lastname: Kolpin
authors.forename: Mary
authors.initials: M
authors.lastname: Skopec
authors.forename: Michael T
authors.initials: MT
authors.lastname: Meyer
authors.forename: Edward T
authors.initials: ET
authors.lastname: Furlong
authors.forename: Steven D
authors.initials: SD
authors.lastname: Zaugg
mesh_terms: D002853:Chromatography, Liquid; D002947:Cities; D004784:Environmental Monitoring / Q000706:statistics & numerical data*; D007484:Iowa; D013058:Mass Spectrometry; D004364:Pharmaceutical Preparations / Q000032:analysis*; D045483:Rivers / Q000737:chemistry*; D014865:Waste Disposal, Fluid
chemical_list: D004364:Pharmaceutical Preparations