METHYLMERCURY IN MOSQUITOES: IMPACT OF A LARGE COAL-FIRED ELECTRICAL UTILITY IN CENTRAL OHIO

Emissions from coal-fired power plants are the major anthropogenic source of mercury (Hg) to the environment. Because emitted Hg can be deposited near the source, there are concerns about effects of coal-burning facilities on levels of toxic methylmercury (MeHg) in biota near such sources. We investigated the potential impact of a large Hg-emitting (> 500 kg Hg y^–1) coal-fired power station in Conesville, OH, on MeHg levels in adult mosquitoes near the plant. Mosquitoes were sampled at 23 locations within a 60-km radius of the plant and at three reference sites distant from major combustion sources of Hg in July 2010. Nearly all of the Hg in mosquitoes was as MeHg (mean = 91%). Concentrations of MeHg in mosquitoes were unrelated to either distance or direction from the Conesville plant and not different from those at the three reference sites. Moreover, measured levels of MeHg in mosquitoes near Conesville are in good agreement with those predicted from an empirical relationship to wet atmospheric Hg fluxes alone. This suggests that either little of the Hg emitted from the Conesville plant is deposited locally or near-source deposition of Hg does not have a significant impact on MeHg in mosquitoes and, by extension, other organisms in the local food web.