Spatial patterns of mercury contamination of fish in the south central United States

Abstract

Mercury (Hg) is a toxic metal that is found in aquatic food webs and is hazardous to humans. An emerging conceptual model predicts areas with the potential to contain food webs with elevated concentrations of Hg receive high amounts of Hg and sulfate deposition, have high coverage of forests and wetlands and low coverage of agriculture. The objective of this study was to test this conceptual model using concentrations of Hg in fish in the south central United States. Coverage by evergreen forests explained 73 percent of the variance of average mercury concentrations in the 14 ecoregions. Over 70% of the water bodies in ecoregions with evergreen forest coverage of 20% or greater have Hg concentrations in largemouth bass above the EPA criterion level of 300 ng/g. Evergreen forests in states in the southern ecoregions may constitute a significant hazard to human health through increased exposure to Hg from fish.