LOCAL IMPACTS OF MERCURY EMISSIONS FROM THE MONTICELLO COAL FIRED POWER PLANT.
The Clean Air Interstate Rule (CAIR) and the Clean Air Mercury Rule (CAMR) as currently proposed by the U.S. Environmental Protection Agency (EPA) when fully implemented will lead to reduction in mercury emissions from coal-fired power plants by 70 percent to fifteen tons per year by 2018. The EPA estimates that mercury deposition would be reduced 8 percent on average in the Eastern United States. The CAMR permits cap-and-trade approach that requires the nationwide emissions to meet the prescribed level, but do not require controls on each individual power plant. This has led to concerns that there may be hot-spots of mercury contamination near power plants. Partially because of this concern, many states including Pennsylvania have implemented, or are considering, state regulations that are stricter on mercury emissions than those in the CAMR. This study examined the possibility that coal-fired power plants act as local sources leading to mercury ''hot spots'', using two types of evidence. First, the world-wide literature was searched for reports of deposition around mercury sources, including coal-fired power plants. Second, soil samples from around two mid-sized U.S. coal-fired power plants were collected and analyzed for evidence of ''hot spots'' and for correlation with model predictions of deposition. The following summarizes our findings from published reports on the impacts of local deposition. In terms of excesses over background the following increments have been observed within a few km of the plant: (A) local soil concentration Hg increments of 30%-60%, (B) sediment increments of 18-30%, (C) wet deposition increments of 11-12%, and (D) fish Hg increments of about 5-6%, based on an empirical finding that fish concentrations are proportional to the square root of deposition. Important uncertainties include possible reductions of RGM to Hg(0) in power plant plumes and the role of water chemistry in the relationship between Hg deposition and fish content. Soil and vegetation sampling programs were performed around the Monticello coal fired power plant. The objectives were to determine if local mercury hot spots exist, to determine if they could be attributed to deposition of coal-fired power plant emissions, and to determine if they correlated with model predictions. The study found the following: (1) There was no correlation between modeled mercury deposition and either soil concentrations or vegetation concentrations. At the Monticello plant, excess soil Hg was associated with soil characteristics with higher values near the lake. Vegetation concentration showed some correlation with soil concentrations having higher mercury in vegetation when the soil mercury. (2) Based on computer modeling, Hg deposition was primarily RGM with much lower deposition from elemental mercury. The total deposition within 50 Km of the plant was predicted to be 4.2% of the total emitted. In the deposition, RGM is responsible for 98.7% of the total deposition, elemental mercury accounts for 1.1% and particulate mercury accounts for 0.2%. Less than 1% of the elemental mercury emitted was predicted to deposit within 50 km.
- Research Organization:
- BROOKAHVEN NATIONAL LABORATORY
- Sponsoring Organization:
- Doe - Office Of Science
- DOE Contract Number:
- DE-AC02-98CH10886
- OSTI ID:
- 899614
- Report Number(s):
- BNL-77475-2007-IR; R&D Project: 13904; TRN: US200709%%181
- Country of Publication:
- United States
- Language:
- English
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