Plume-in-grid modeling of atmospheric mercury

Author: K. Vijayaraghavan, P. Karamchandani, C. Seigneur, R. Balmori and S.‐Y. Chen
Date: 
December 30, 2008
Type: 
Journal Article
Venue: 
Journal of Geophysical Research
Citation: 

Vijayaraghavan, K., P. Karamchandani, C. Seigneur, R. Balmori, and S.‐Y. Chen (2008), Plume‐in‐grid modeling of atmospheric mercury, J. Geophys. Res., 113, D24305, doi:10.1029/2008JD010580.

An existing plume-in-grid model for ozone and particulate matter, which provides an explicit treatment of stack plumes embedded within a three-dimensional grid-based Eulerian air quality model, is extended to include a comprehensive treatment of mercury (Hg) processes. The model is applied to the continental United States to investigate the subgrid-scale effects associated with Hg emissions from large elevated point sources on atmospheric Hg concentrations and deposition. The top thirty Hg-emitting power plants in the U.S. were selected for explicit plume-in-grid treatment. Two new processes are included in the Hg chemical mechanism: the gas-phase adsorption of reactive gaseous mercury (RGM) on atmospheric particulate matter and the reduction of RGM to elemental Hg by sulfur dioxide. The plume-in-grid treatment results in improved performance for Hg wet deposition over a purely Eulerian grid-based model, partial correction of overpredictions of wet deposition downwind of coal-fired power plants in the northeastern U.S., and decreases of approximately 10% in simulated dry and wet deposition over large parts of the eastern U.S., with larger decreases near the plants selected for plume-in-grid treatment. On average, 23% of ambient RGM is modeled to adsorb on atmospheric particulate matter.