Pharmaceuticals and organochlorine pesticides in sediments of an urban river in Florida, USA

Sediments from a rural to urban gradient along the Alafia River in Florida, USA, were collected to determine the risk of environmental contamination with legacy (organochlorine pesticides (OCPs)) and new contaminants (pharmaceuticals). Bed sediments (0-10 cm) collected from rural and urban sub-basins of the Alafia River were analyzed for OCPs and pharmaceuticals using standard gas chromatography and liquid chromatography-mass spectrometry techniques. Three most frequently detected pharmaceuticals in sediments were carbamazepine (100 % of samples), trimethoprim (89 % of samples), and pseudoephedrine (63 % of samples). While acetaminophen, diphenhydramine, lidocaine, and nicotine were detected in < 30 % of samples. The detection of caffeine in all sediment samples suggests that domestic wastewater from wastewater treatment plants and/or septic systems may be a contributing source at all the sites. Among the OCPs, endosulfan I was most frequently detected (37 % of samples), followed by delta-hexachlorocyclohexane (15 % of samples), gamma-chlordane and endosulfan II (both in 11 % of samples), and dichlorodiphenyldichloroethylene and methoxychlor (both in 7 % of samples). The lower concentrations of OCPs (sum 0-16.1 ng g(-1)) than pharmaceuticals (sum 0.5-61.9 ng g(-1)) in sediments are probably due to the historic use of OCPs since these were banned for use in the USA in the 1970s, while pharmaceuticals are still used. The variability in detection and concentrations of legacy and new compounds in rural and urban stream sediments is likely due to the different magnitude of input sources, site characteristics, and chemical properties of individual compounds. Significant positive correlations between OCPs and sediment properties (organic matter, silt, and clay) suggest that sediments are a major sink of various contaminants in the Alafia River. We conclude that the concentrations of both pharmaceuticals and OCPs in sediments of this urban river are relatively lower than existing literature; however, these can still be of environmental concern to aquatic organisms.