Mercury concentrations in wetlands associated with coal-fired power plants.

There have been contradictory reports of the relative proportion of mercury from coal-fired power plants that deposits locally. Our objective was to determine any local effect of coal-fired power plants on total mercury concentrations in wetland sediment and tadpole samples. Four power plants and 45 wetlands were selected for study. Total mercury concentrations were determined in 75 sediment samples (range: 8-82 ng/g dry weight) and 100 bullfrog (Lithobates catesbeiana) and green frog (Lithobates clamitans) tadpoles (range: 5-318 ng/g wet weight). Tadpole and sediment total mercury did not significantly vary by power plant or distance from the plant. Only one power plant had a significantly greater concentration of total mercury in sediment downwind compared to upwind wetlands. A similar (but non-significant) trend was found for tadpole total mercury surrounding the same plant. Tadpole total mercury was negatively correlated with both tadpole weight and total length. Tadpole and sediment total mercury concentrations were not significantly correlated with one another. The results of the current study suggest that coal-fired power plants are not significantly affecting mercury concentrations in surrounding wetlands.