National Water Quality Assessment Program: Eastern Iowa Basins

Persistence Of Selected Organochlorine Compounds In Fish Tissue In The Upper Mississippi River Hydrologic System

Linda R. Roberts U.S. Geological Survey, Iowa City, IA
Kathy E. Lee U.S. Geological Survey, Mounds View, MN
Mitchell A. Harris U.S. Geological Survey, Urbana, IL
Stephen D. Porter U.S. Geological Survey, Lakewood, CO

Program abstracts of the 45th annual meeting of the North American Benthological Society, May 26-30, 1997, San Marcos, TX

Concentrations of organochlorine insecticides and other contaminants were determined in whole fish (Cyprinus carpio, Catostomus commersoni, Moxostoma erythrurum, and M. macrolepidotum) samples collected from 43 sites in the upper Mississippi River hydrologic system in Minnesota, Iowa, and Illinois. This study, a part of the U.S. Geological Survey's National Water-Quality Assessment (NAWQA) Program, was designed to investigate relations of contaminant concentrations in fish to land-use practices. Total DDT and PCB concentrations appeared to be related to both agricultural and urban influences. Although PCB, DDE, and chlordane were commonly detected in urban streams, tissue concentrations of chlordane, heptachlor epoxide, and dieldrin were greater in agricultural than urban settings. Few detections of contaminants were found in fish from forested streams in Minnesota. Total orgaonchlorine concentrations in fish tissue from many Illinois and Iowa streams exceeded national averages from previous NAWQA tissue studies. Average concentrations of most insecticides were greatest in Illinois fish tissue, whereas concentrations of DDE were greater in Iowa than in Illinois or Minnesota. Although use of DDT was banned in 1972, low concentrations of p,p'-DDT were detected in fish samples from more than 10 percent of the sites in the study.

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