LOCAL IMPACTS OF MERCURY EMISSIONS FROM COAL FIRED POWER PLANTS.

Mercury is a neurotoxin that accumulates in the food chain and is therefore a health concern. The primary human exposure pathway is through fish consumption. Coal-fired power plants emit mercury and there is uncertainty over whether this creates localized hot spots of mercury leading to substantially higher levels of mercury in water bodies and therefore higher exposure. To obtain direct evidence of local deposition patterns, soil and vegetations samples from around three U.S. coal-fired power plants were collected and analyzed for evidence of hot spots and for correlation with model predictions of deposition. At all three sites, there was no correlation between modeled mercury deposition and either soil concentrations or vegetation concentrations. It was estimated that less than 2% of the total mercury emissions from these plants deposited within 15 km of these plants. These small percentages of deposition are consistent with the literature review findings of only minor perturbations in environmental levels, as opposed to hot spots, near the plants. The major objective of the sampling studies was to determine if there was evidence for hot spots of mercury deposition around coal-fired power plants. From a public health perspective, such a hot spot must be large enough to insure that it did not occur by chance, and it must increase mercury concentrations to a level in which health effects are a concern in a water body large enough to support a population of subsistence fishers. The results of this study suggest that neither of these conditions has been met