Speciated mercury emissions from laboratory combustion of wildland fuel

1. Speciated mercury emissions from laboratory combustion of wildland fuel D. Obrist, H. Moosmüller, Desert Research Institute, Reno, NV C. Wold, E.N. Lincoln, P. Freeborn, and W.-M. Hao, USDA Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory, Missoula, MT S. Kreidenweis, Colorado State University, Fort Collins, CO • Importance: • Atmospheric Hg deposition is the major source of Hg contamination in remote systems • Hg emissions from wildfires globally an important source to atmospheric Hg load (>500 tons/year) • Speciation of emissions unlcear:  if Hg-0 (elemental gasous form): emissions likely enter global atmospheric Hg pool •  if Hg-P (particulate-phase form): emissions likely deposit locally Methods: • Mercury analyses • Hg-0: Tekran 2537 gaseous mercury analyzer; 1.5 l min-1; 0.2m Teflon filters; acid-cleaned teflon filters and lines • Hg-P: Pre-heated quartz-fiber filters; 50 l min-1; Analysis (Frontier Geosciences: BrCl digestion; SnCl2 reduction; dual amalgamation; CVAFS detection) USFS Fire Science Lab: Biomass Combustion and Smoke Stack Sampling Results: Percentage Hg-P of total Hg emission as a function of: (c) Fuel Moisture (B) Fuel Type (A) Combustion Phase Conclusions ●Speciation between Hg-0 and Hg-P emissions from biomass combustion largely determined by fuel moisture ● Green, fresh biomass combustion results in high Hg-P contributions (up to 40% of total Hg emissions) ● Wildfires may contribute significantly to local Hg deposition when green leaves and branches are burned Funding of this study was provided by the NSF Atmospheric Chemistry program (ATM-0632780 ) and by the Joint Fire Science Program Acknowledgement