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Surface Ocean and Lower Atmosphere Study—Air-Sea interactions and their climatic and environmental impacts
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Marine Fine Aerosols in South China Sea - Chemical Characteristics and Source Apportionment
Wednesday 9th @ 1010-1030, Conference Room 7
Chung-Shin Yuan* , Institute of Environmental Engineering, National Sun Yat-sen University
Chung-Min Hung, Institute of Environmental Engineering, National Sun Yat-sen University
Zong-Mou Yang, Institute of Environmental Engineering, National Sun Yat-sen University
Po-Hung Cheng, Institute of Environmental Engineering, National Sun Yat-sen University
Presenter Email: ycsngi@mail.nsysu.edu.tw |
| This study aims to explore the chemical characteristics and source apportionment of marine PM2.5 in South China Sea. Regular and intensive sampling of PM2.5 were conducted simultaneously at the Dongsha Islands and the Nansha Islands from August 2017 to April 2018. Chemical composition including water-soluble ions (WSIs), metallic elements, carbonaceous contents, anhydrosugars, and organic acids were further analyzed to characterize the chemical fingerprint of marine PM2.5 in South China Sea. Furthermore, backward trajectory simulation and chemical mass balance (CMB) receptor modelling were applied to identify the potential sources of marine PM2.5 and their contribution in each season. Field sampling results indicated that high concentrations of marine PM2.5 were observed in winter and spring. During the northeastern monsoons periods, anthropogenic PM2.5 from northern region was brought to South China Sea, resulting in significant increase of PM2.5 concentration. Chemical analytical results showed that secondary inorganic aerosols (NO3-, SO42-, and NH4+) dominated WSIs, accounting for 47.6-70.4% of WSIs in winter and spring. Crustal elements (Ca, K, Mg, Fe, Al) dominated the metallic elements in PM2.5. The concentrations of trace metals (V, Cr, Mn, Ni, Zn, and Cd) were emitted from anthropogenic emissions since fall. Moreover, organic carbon (OC) was the dominant carbonaceous species during the sampling periods, and OC/EC ratios increased during the northeastern monsoon periods. The concentrations of levoglucosan at the sampling sites were ordered as DS>NS. The highest levoglucosan concentrations of 13.73 ng/m3 were observed at the Dongsha Islands. Organic acids of PM2.5 at the Dongsha Islands were higher than those at the Nansha Islands. Oxalic acid was the abundant organic acids in PM2.5. The concentrations of oxalic acid at all sampling sites ranged from 5.1 to 189.4 ng/m3. The mass ratios of malonic and succinic acids (M/S ratios) in PM2.5 ranged from 0.99 to 1.41, showing that PM2.5 was mainly attributed from secondary organic aerosols (SOAs). Sea salts, fugitive dusts, and mobile sources were the major sources at two sampling sites, but the contribution of anthropogenic sources (i.e. incinerators, petrochemical industries, industrial boilers, secondary sulfate and nitrate, and organic carbon) and biomass burning rose up since fall. |
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