Source categories and contribution of biomass smoke to organic aerosol over the southeastern Tibetan Plateau

An intensive measurement campaign was conducted at a mountain and suburban site at the edge of the southeastern Tibetan Plateau during spring. Concentrations of PM2.5, carbonaceous species (OC and EC) and anhydrosugars (levoglucosan, mannosan and galactosan) as well as their ratios were utilized to identify possible biomass burning categories and contributions of biomass burning smoke to ambient aerosols. The average concentrations of levoglucosan and mannosan were 193.8 and 12.4 ng m(-3), respectively at the mountain site, and 713 and 61.5 ng m(-3) respectively at the suburban site. According to characteristic levoglucosan/mannosan (Lev/Man) and mannosan/galactosan (Man/Gal) ratios, we identified for the first time that mixed smoke particles (18.5, 72.3 and 9.1% for crop residues, softwood and hard wood respectively) derived from the study region and Southeast Asia contributed to the aerosol burden in the southeastern Tibetan Plateau. The biomass smoke contributions to organic carbon and organic matter were estimated to be 28.4% and 18.9-25.7% respectively at the mountain site and 38.3% and 33.5-45.4% respectively at the suburban site. The large contribution estimates indicate that biomass burning was an important anthropogenic/natural source of aerosol particles which impact regional atmospheric chemistry and climate in the southeastern Tibetan Plateau. (c) 2012 Elsevier Ltd. All rights reserved.