Mercury Contamination in Forest and Freshwater Ecosystems in the Northeastern United States

TLDR

Elevated atmospheric mercury deposition in eastern North America, driven by emissions from electric utilities, incinerators, and industry, leads to high mercury concentrations in wetland‑rich forests and freshwater biota, posing a risk of methylmercury bioaccumulation through the food chain. U.S. electric utilities are implementing measures that aim to cut mercury emissions by about 70%.

Abstract

Eastern North America receives elevated atmospheric mercury deposition from a combination of local, regional, and global sources. Anthropogenic emissions originate largely from electric utilities, incinerators, and industrial processes. The mercury species in these emissions have variable atmospheric residence times, which influence their atmospheric transport and deposition patterns. Forested regions with a prevalence of wetlands and of unproductive surface waters promote high concentrations of mercury in freshwater biota and thus are particularly sensitive to mercury deposition. Through fish consumption, humans and wildlife are exposed to methylmercury, which markedly bioaccumulates up the freshwater food chain. Average mercury concentrations in yellow perch fillets exceed the Environmental Protection Agency's human health criterion across the region, and mercury concentrations are high enough in piscivorous wildlife to cause adverse behavioral, physiological, and reproductive effects. Initiatives are under way to decrease mercury emissions from electric utilities in the United States by roughly 70%.