Modeling atmospheric mercury deposition in the vicinity of power plants.
Two mathematical models of the atmospheric fate and transport of mercury (Hg), an Eulerian grid-based model and a Gaussian plume model, are used to calculate the atmospheric deposition of Hg in the vicinity (i.e., within 50 km) of five coal-fired power plants. The former is applied using two different horizontal resolutions: coarse (84 km) and fine (16.7 km). More than 96% of the power plant Hg emissions are calculated with the plume model to be transported beyond 50 km from the plants. The grid-based model predicts a lower fraction to be transported beyond 50 km: >91% with a coarse resolution and >95% with a fine resolution. The contribution of the power plant emissions to total Hg deposition within a radius of 50 km from the plants is calculated to be <8% with the plume model, <14% with the Eulerian model with a coarse resolution, and <10% with the Eulerian model with a fine resolution. The Eulerian grid-based model predicts greater local impacts than the plume model because of artificially enhanced vertical dispersion; the former predicts about twice as much Hg deposition as the latter when the area considered is commensurate with the resolution of the grid-based model. If one compares the local impacts for an area that is significantly less than the grid-based model resolution, then the grid-based model may predict lower local deposition than the plume model, because two compensating errors affect the results obtained with the grid-based model: initial dilution of the power plant emissions within one or more grid cells and enhanced vertical mixing to the ground.
Seigneur
Christian
C
Atmospheric and Environmental Research, Inc., San Ramon, CA 94583, USA. seigneur@aer.com
Lohman
Kristen
K
Vijayaraghavan
Krish
K
Jansen
John
J
Levin
Leonard
L
D000393:Air Pollutants / Q000032:analysis*; D003031:Coal; D003198:Computer Simulation; D008628:Mercury / Q000032:analysis*; D008962:Models, Theoretical; D011210:Power Plants; D014919:Wind
D000393:Air Pollutants; D003031:Coal; D008628:Mercury