Effect of Biomass Fires on Atmospheric Mercury Concentrations and Deposition in the United States

Krish Vijayaraghavan
Atmospheric & Environmental Research, Inc. (AER),
San Ramon, CA USA

Summer-time wildfires frequently occur in several regions of North America. Human-initiated burning of ground cover is also commonly employed for land clearing and land-use change. Measurements have found that such biomass burning, both lightning-induced and prescribed, can release significant levels of mercury into the air. These emissions comprise almost exclusively gaseous elemental mercury (Hg0) and particulate mercury (Hgp), and little reactive gaseous mercury (RGM). This paper investigates the effect of mercury emissions from biomass fires on atmospheric mercury concentrations and deposition in the United States during 2002 using an advanced air quality model. The model used, AMSTERDAM (Advanced Modeling System for the Transport, Emissions, Reactions and Deposition of Atmospheric Matter) is a state-of-the-science multi-pollutant model that is based on USEPA’s Community Multiscale Air Quality (CMAQ) model and offers sophisticated treatments of ozone, particulate matter and mercury processes. Model performance is evaluated using mercury wet deposition data from the Mercury Deposition Network (MDN) and other measurements. The impact of fire Hg emissions on air concentrations and wet and dry deposition of Hg0, RGM and Hgp in the continental United States is studied.