AAAR 32nd Annual Conference
September 30 - October 4, 2013
Oregon Convention Center
Portland, Oregon, USA
Abstract View
Radiocarbon-Based Source Apportionment of EC and OC in Fine Particulate Matter at a Regional Background Site on Hainan Island, South China
YANLIN ZHANG, Jun Li, Gan Zhang, Jianhui Tang, Peter Zotter, Lukas Wacker, Andre Prévôt, Soenke Szidat, University of Bern
Abstract Number: 183 Working Group: Source Apportionment
Abstract Atmospheric aerosol particles are of worldwide concern for their important effects on climate and human health. Both fossil fuel emissions and biomass burning in Southeast Asia have an important impact on regional particles emissions. To study air pollution outflows from mainland China as well as the impact of Southeast Asian biomass-burning emissions, PM2.5 samples were collected during May 2005-August 2006 at a regional background site of Jianfeng on Hainan Island, South China. The concentrations of elemental carbon (EC) and organic carbon (OC) in PM2.5 were characterized by the lowest abundances during the wet summer season and the highest levels in winter. The observations were associated to wet deposition and the prevailing clean maritime air mass origins in summer on the one hand and the anthropogenic air pollutions transport from continental China with the northeast winds on the other hand. To assign fossil and non-fossil contributions of carbonaceous particles, we analyzed radiocarbon ($^(14)C) contents in EC, OC and water-insoluble OC (WINSOC) with the newly developed protocol Swiss_4S. On average, the contributions of fossil sources to EC and OC were 40% and 20%, respectively, indicating generally a dominance of non-fossil emissions. Relatively higher contributions from fossil sources to EC and OC were observed, when air masses originated from Southeast China during low fire periods. The increasing of fossil carbon was associated to long-range transport of particles emitted from fossil-fuel combustion and vehicular emissions in highly urbanized regions of China. An increase of non-fossil contribution by 10-20% was observed during periods with enhanced open biomass-burning activity in Southeast Asia or Southeast China. In addition, a modified EC tracer method was used to estimate the fossil-derived SOC formation with measurement of fossil WINSOC and fossil EC determined by $^(14)C. The results indicate that fossil OC at this site was rather from secondary than primary sources.