Plume‐in‐grid modeling of atmospheric mercury

Abstract

[1] 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.

An assessment of atmospheric mercury in the Community Multiscale Air Quality (CMAQ) model at an urban site and a rural site in the Great Lakes Region of North America

“…−9 % (annual, lower resolution) (Seigneur et al, 2003), −11 % (Seigneur et al, 2003b), and others (Cohen et al, 2004;Gbor et al, 2006); and have little bias -e.g. Vijayaraghavan et al (2008). Values of R 2 emerging from the literature vary widely, although our annual R 2 value of 0.27 is lower than the range of 0.50-0.69 found in Bullock et al (2009).…”

“…A number of studies have used these data to evaluate CMAQ-Hg (Bash, 2010;Bullock and Brehme, 2002;Bullock et al, 2008Bullock et al, , 2009Gbor et al, 2006Gbor et al, , 2007Lin et al, 2007;Lin and Tao, 2003;Pongprueksa et al, 2008;Sunderland et al, 2008;Vijayaraghavan et al, 2007), and other atmospheric chemistry models that include mercury (Cohen et al, 2004;Holmes et al, 2010;Sanei et al, 2010;Seigneur et al, 2003;Selin and Jacob, 2008;Vijayaraghavan et al, 2008). Until recently, most studies that evaluate model estimates of ambient mercury compare with Total Gaseous Mercury (TGM) and/or Hg 0 (Gbor et al, 2006(Gbor et al, , 2007Holmes et al, 2010;Lin and Tao, 2003;Lohman et al, 2008;Selin et al, 2007;Soerensen et al, 2010;Wen et al, 2011).…”

Sub-Grid Scale Plume Modeling

“…The model was applied for 2001 over a domain covering the U.S. at 36 km horizontal resolution [91]. The top thirty Hg emitting power plants in the U.S. were selected for explicit plume treatment.…”

“…The next stage in the development of CMAQ-APT was the inclusion of mercury (Hg) treatment [90,91]. The model was applied for 2001 over a domain covering the U.S. at 36 km horizontal resolution [91].…”

Gas-particle partitioning of atmospheric Hg(II) and its effect on global mercury deposition

“…In more recent years, models of atmospheric Hg have taken various approaches to treating Hg(II) gas-particle partitioning. Vijayaraghavan et al (2008) implemented the temperature-dependent Hg(II) gas-particle partitioning formulation of Rutter and Schauer (2007b) into a regional model for the United States. Previous versions of GEOS-Chem have either assumed atmospheric Hg(II) to be entirely gas-phase (Selin et al, 2007 or 50/50 gas/particle .…”