ELEMENTAL CHARACTERIZATION OF PARTICULATE MATTER EMITTED FROM BIOMASSBURNING - WIND-TUNNEL DERIVED SOURCE PROFILES FOR HERBACEOUS AND WOODFUELS

Particulate matter emitted from wind tunnel simulations of biomass bur ning for five herbaceous crop residues (rice, wheat and barley straws, corn stover and sugar cane trash) and four wood fuels (walnut and alm ond prunings and ponderosa pine and Douglas fir slash) was collected a nd analyzed for major elements and water soluble species. Primary cons tituents of the particulate matter were C, K, Cl, and S. Carbon accoun ted for roughly 50% of the herbaceous fuel PM and about 70% for the wo od fuels. For the herbaceous fuels, particulate matter from rice straw in the size range below 10 mu m aerodynamic diameter (PM10) had the h ighest concentrations of both K (24%) and Cl, (17%) and barley straw P M10 contained the highest sulfur content (4%). K, Cl, and S were prese nt in the PM of the wood fuels at reduced levels with maximum concentr ations of 6.5% (almond prunings), 3% (walnut prunings), and 2% (almond prunings), respectively. Analysis of water soluble species indicated that ionic forms of K, Cl, and S made up the majority of these element s from all fuels. Element balances showed K, Cl, S, and N to have the highest recovery factors (fraction of fuel element found in the partic ulate matter) in the PM of the elements analyzed. In general, chlorine was the most efficiently recovered element for the herbaceous fuels ( 10 to 35%), whereas sulfur recovery was greatest for the wood fuels (2 5 to 45%), Unique potassium to elemental carbon ratios of 0.20 and 0.9 5 were computed for particulate matter (PM10 K/C(e)) from herbaceous a nd wood fuels, respectively. Similarly, in the size class below 2.5 mu m, high-temperature elemental carbon to bromine (PM2.5 C(eht)/Br) rat ios of similar to 7.5, 43, and 150 were found for the herbaceous fuels , orchard prunings, and forest slash, respectively. The molar ratios o f particulate phase bromine to gas phase CO2 (PM10 Br/CO2) are of the same order of magnitude as gas phase CH3Br/CO2 reported by others.