Screening Historical Water Quality Monitoring Data for Chemicals of Potential Ecological Concern: Hazard Assessment for Selected Inflow and Outflow Monitoring Stations at the Water Conservation Areas, South Florida

Abstract

A hazard assessment was conducted of contaminants found at inflow and outflow monitoring stations of the Water Conservation Areas (WCAs) in South Florida. WCAs (1, 2A, 2B 3A, 3B) lie north of Everglades National Park (ENP) and southeast of Lake Okeechobee, span almost 1400 mi2, and serve a number of water resource functions which include food control for three major counties, delivering water to ENP, and water storage during dry downs and for recharging groundwater. Measured concentrations of contaminants in sediment and water were evaluated at 13 monitoring stations in the WCAs using a screening benchmark approach. Chemicals of potential ecological concern (COPECs) included herbicides, organochlorine pesticides, organochlorine industrial chemicals, and heavy metals. Of the stations, total cadmium was a COPEC at nine of them. Most sites had maximum detected concentrations of cadmium that exceeded state of Florida (USA) water quality criteria standards. Beryllium, copper, mercury, methylmercury, and zinc (measured as total metal concentration) also exceeded surface water criteria at several sites. Several organochlorine chemicals in sediment were COPECs; chlordane, polychlorinated biphenyls, and p,p′-DDT with its metabolites (p,p′-DDD and p,p′-DDE) had more than 200 sediment benchmark exceedences. Mercury in fish tissue was a COPEC at S5A when compared to a no-effect residue value for survival. Greater potential hazards were observed at northern monitoring sites than southern sites around the WCAs. The hazard assessment approach for screening water quality data described in this article can help focus higher tier risk assessment work, including laboratory, field, and data analysis studies, on contaminants with greater potential for adverse biological effects.