Agricultural Fires in the Southeastern U.S. during SEAC4RS: Emissions of Trace Gases and Particles and Evolution of Reactive Nitrogen and Ozone
Friday, 19 December 2014: 9:00 AM
Biomass burning produces significant amounts of trace gases and aerosol particles, which play important roles in atmospheric chemistry and climate. However, few measurements of biomass burning have been made in temperate regions. This study quantifies the emission factors of trace gases and fine particles from 16 agricultural fires in the southeastern U.S. sampled during the SEAC4RS campaign. The evolution of reactive nitrogen species (PANs, NOx, and nitrate) and ozone in these fire plumes was also studied. The agricultural fires emitted significant levels of sulfur and chlorine. Sulfur was mainly emitted as SO2 while chlorine was mainly found in the form of particulate chloride. The preliminary emission factors of SO2, sulfate, and chloride are larger than those for other types of biomass burning with average values of 0.92±0.50, 0.21±0.19, and 1.1±0.73 g/kg. Emission factors of other major gaseous (such as hydrogen cyanide, hydroxyacetone, acetonitrile, and monoterpenes) and particulate species (such as nitrate and ammonium) and their variations in agricultural fires will also be examined. PAN was found to form very rapidly in the sampled plumes of agricultural fires. The ratio of PAN to NOy reached up to 40% in less than 1 hour. Other peroxyacyl nitrates (APAN, PPN, and PiBN) all formed rapidly at similar speeds. O3 formation occurred in most agricultural fire plumes but O3 destruction was also observed.