Mercury levels in Wisconsin fish and wildlife

Abstract

Mercury determinations were made on 1824 fish fillet samples representing 139 locations covering 52 of Wisconsin's 72 counties and boundary waters of Lake Michigan, Green Bay, Lake Superior, and the Mississippi River. Mercury levels in fish from waters removed from any known source of mercury use averaged .19 ppm and ranged between .01 and .60 ppm mercury. The highest mercury levels, averaging about 1 ppm and ranging between .10 and 4.89 ppm, occurred in fish taken from sections of the Chippewa, Flambeau, and Wisconsin Rivers located below paper mills and below a mercury cell chlorine-caustic soda plant. Fish samples taken from the following areas contained mercury levels averaging above the .5 ppm guideline established by the Food and Drug Administration for banning fish from interstate markets: the 350-mile stretch of the Wisconsin River below Rhinelander, 40 miles of the Flambeau River between Cedar Rapids and the junction with the Chippewa River, and 50 miles of the Chippewa River from the junction with the Flambeau River to Eau Claire. Mercury determinations were made on 234 wildlife muscle samples and 220 wildlife liver samples. Mercury levels in muscle and liver tissue of most Wisconsin wildlife was well below .5 ppm. Water birds,more » including waterfowl, contained more mercury than mammals or upland game birds. Livers of diving ducks, herons, and grebes approached or exceeded .5 ppm. No geographic locations were noted where mercury seemed to be more concentrated in wildlife. 2 figures, 8 tables.« less