Mercury Data from Small Lakes in Voyageurs National Park, Northern Minnesota, 2000–02

Mercury contamination of aquatic ecosystems is a resource concern in Voyageurs National Park. High concentrations of mercury in fish pose a potential risk to organisms that consume large amounts of those fish. During 2000–02, the U.S. Geological Survey measured mercury in water collected from 20 lakes in Voyageurs National Park. Those lakes span a gradient in fish-mercury concentrations, and also span gradients in other environmental variables that are thought to influence mercury cycling. During 2001, near surface methylmercury concentrations ranged from below the method detection limit of 0.04 nanograms per liter (ng/L) to 0.41 ng/L. Near surface total mercury concentrations ranged from 0.34 ng/L to 3.74 ng/L. Hypolimnetic methylmercury ranged from below detection to 2.69 ng/L, and hypolimnetic total mercury concentrations ranged from 0.34 ng/L to 7.16 ng/L. During 2002, near surface methylmercury concentrations ranged from below the method detection limit to 0.46 ng/L, and near surface total mercury ranged from 0.34 ng/L to 4.81 ng/L. {The abstract, table 4, and table 6 were corrected on 14 July 2006.}