National Water-Quality Assessment Program: Environmental Distribution of Organochlorine Compounds in the Apalachicola-Chattahoochee-Flint River Basin

Abstract

The Apalachicola-Chattahoochee-Flint River basin, which drains about 20,000 square miles of Georgia, Florida, and Alabama, is one of 20 large hydrologic systems included in the first phase (1991-1996) of the U.S. Geological Survey’s National Water-Quality Assessment program. One component of this program is the assessment of the occurrence and distribution of organochlorine compounds (pesticides and PCB’s) in bed sediments and aquatic life in hydrologic settings representing ranges in drainage order, physiography, geology, climate, and land use. During August and November, 1992, and August and September, 1993, 37 stream sites and 7 reservoir sites in the ACF River basin were sampled for bed sediment (mineral and organic matter less than 2mm) and either Corbicula fluminea (Asiatic clam) or Gambusia affinis holbrooki (mosquitofish). Bed sediments and tissues were analyzed for 38 organochlorine compounds. Results of these analyses are summarized and compared with historic data reported by Federal and State agencies. DDD, DDE, DDT, chlordane, dieldrin, and total PCB’s were the most frequently detected organochlorine compounds in the ACF River basin, with detectable concentrations measured in more than 10 percent of samples. DDT and its homologs are widely distributed, but concentrations are much lower in recent (1992 and 1993) years. The widespread distribution and potential for continued bioaccumulation of chlordane and PCB’s warrant their continued monitoring and assessment. Aldrin, heptachlor, toxaphene, endrin, endosulfan, methoxychlor, and hexachlorobenzene either were not detected or were detected in 2 percent or less of water samples.