RESUMO
We report on mercury (Hg) contamination in waters, sediments, and biota of Vermont and New Hampshire (USA) lakes measured during 1998-2000, using a geographically randomized design. Waters and sediments of 92 lakes were sampled for mercury, methylmercury, and ancillary parameters. Yellow perch (Perca flavescens) muscle tissues were analyzed for mercury on 47 of these lakes. Interannual variation in mercury was limited; only epilimnetic Hg was elevated by approximately 1.5 ng/L in 1998 over remaining years because of wet weather. Aqueous total and methylmercury concentrations were elevated in both dystrophic and eutrophic lakes over other types. Yellow perch tissue concentrations were elevated by 0.218 microg/g in dystrophic lakes over other types and were very low in eutrophic lakes. Fish tissue mercury concentrations showed no relationship to hypolimnetic or sediment mercury or methylmercury. A statistical model indicated that yellow perch tissues in 40.2 +/- 13% of lakes were likely to exceed the U.S. Environmental Protection Agency (U.S. EPA) methylmercury criterion of 0.3 microg/g, and yellow perch from New Hampshire were twice as likely to exceed the criterion as those from Vermont. Results of this study provide a regional-scale baseline against which the success of future reductions in mercury emissions can be assessed.
