Effect of Biomass Burning on the Light Absorption Properties of Water Soluble Organic Carbon in Atmospheric Particulate Matter in Changchun

To investigate the effect of biomass burning in Changchun in autumn on the absorbance of water-soluble organic carbon (WSOC) on PM2.5, PM2.5 samples were collected from October to November 2017. The light absorption characteristics of WSOC, carbonaceous components, and carbohydrate content in PM2.5 were analyzed. The study showed that the average concentrations of WSOC, organic carbon (OC), and elemental carbon (EC) in PM2.5 in Changchun were (10.12±3.47), (17.07±5.64), and (1.34±0.75) μg·m-3, respectively; the average contribution rate of secondary organic carbon (SOC) to OC was 38.93%. The total sugar concentration in Changchun is (1049.39±958.85) ng·m-3, of which the content of anhydroglucose (L-glucan, galactan, and mannan), as a biomass burning tracer in total sugar, was 91.69%. The results of sugar correlation analysis showed that biomass combustion was the main source of contribution to carbohydrates in the autumn of Changchun. The light absorption wavelength index of WSOC in autumn was 5.75±1.06, and the unit mass absorption efficiency was (1.23±0.28) m2·g-1, indicating that biomass combustion has an important influence on WSOC absorbance. The biomass combustion characteristic source parameter was used to quantify the contribution of biomass burning to WSOC concentration, which was found to be 58.82%, while the contribution to total WSOC light absorption was 40.92%.