Mercury Levels in Fish from Otsego Lake


James A.  Eilers
School of Science and Natural Resources
Lake Supenor State Lniversity
Sau1t Ste Marie MI 49783

Abstract

	Mercury has long been an environmental problem and has been recognized as one
of the pnmary pollutants of concern in Michigan. The main ources of mercury pollution
are coal-fired power plants and industrial processes. These man made sources account for
approximately two-thirds of the mercury in the atmosphere.  Of these two sources
atmosphenc deposition is the main source of mercury contamination in inland lakes in
Michigan. All inland lakes in Michigan have the potential to contain elevated levels of
mercury even if they are in remote locations or don't have any industry along their shore
Since 1983 the Department of Natural Resources (MDNR) has tested 200 of Michigan's
inland lakes and found that 70% contain detectable levels of mercury. The presence of
mercury contamination has prompted the Michigan Department of Public Health (MDPH)
to issue statewide fish consumption advisories for each Great Lake watershed.  The
advisorv for inland lakes states. "No one should eat more than one meal of fish per week
from any inland lake in Michigan" Since no lake in Olsego County had been tested  I
chose to test fish from Otsego Lake because it is the largest lake in that county. I tested
the lake to detennine if fish from Otsego Lake had levels of mercury above regulatory
guidelines now set at 0.5 ppm Hg.
	Ten samples were collected during the summer of 1995.  They were analyzed
using the cold vapor atomic absorption technique. The calibration curve and the standard
addition methods were used to analyze the samples. The instrument could detect mercury
levels to below the 0.5 ppm limit and I found no samples to contain mercury in the fish at
the instrument's level of detection. Based on this study the fish sampled were safe for
consumption.

Selected References

MDPH	Health Risk Assessment Laboratory. "Total Mercury by Cold Vapor Atomic
Absorption." Draft September, 1994.
MDNR Fisheries Division. " 1995 Michigan Fishing Guide. " April 1995.
MDPH	Division ofHealth Risk Assessment. "Contamination Trends in Fish Tissue."
Status Report January 1993.
Hildebrand S Strand R and Huckabee, J  1980 Mercuiy Accumulation in Fish and
	 Invertebrates of the North Folk Holston River Virginia and Tennessee Journal of
	Environmental Quality, Vol 9 no 3