AAAR 37th Annual Conference October 14 - October 18, 2019 Oregon Convention Center Portland, Oregon, USA
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Comparison of Chemical Characteristics of PM2.5 during Winter Haze Events in Beijing, China and Gwangju, Korea
MINHAN PARK, Jihyo Chong, Haebum Lee, Nohhyeon Kwak, Hyunok Maeng, Kyungjoo Kim, Eunbi Lee, Enrique Cosep, A. Young Choi, Hangyul Song, Ma. Cristine Faye Denna, Dahye Oh, Min-Suk Bae, Kyoung-Soon Jang, Min Hu, Xiaoyang Yang, Kihong Park, Gwangju Institute of Science and Technology
Abstract Number: 241 Working Group: Urban Aerosols
Abstract Particulate matter less than 2.5 µm (PM2.5) in the ambient atmosphere is of great interest due to its effects on human health and climate change via radiation balance and cloud formation. Simultaneous measurements of chemical characteristics (ions, elements, elemental carbon, organic carbon, organic compounds, and Pb isotopes) of PM2.5 were conducted during wintertime (1/3/2018-2/2/2018) at urban sites (Beijing, China and Gwangju, Korea). Filter samples were collected daily for offline measurements such as ions, organic carbon (OC), elemental carbon (EC) and elements as well as organic compounds and Pb isotopes at both sites. The average mass concentration of PM2.5 at Beijing was much higher than those at other sites; Beijing (62.45±34.09 μg/m3) and Gwangju (26.77±13.91 μg/m3). The PM2.5 in Beijing was dominated by elements (35.9%), followed by carbonaceous species (OC and EC) (27.9%) and ions (21.7%). In the case of the PM2.5 at Gwangju, ionic components (49.6%) has the highest fractions, followed by carbonaceous species (20.4%) and elements (10.9%). Significant different chemical characteristics were found between two urban sites with the higher fractions of Ca2+, Mg2+, Cl-, and K+ in ions, Ca, Fe, Si, Mg, and Al in elements, PAHs, hopanes and steranes, alkanes, and cycloalkanes in organic compounds, and CHON and CHN organic groups with higher S/C, and N/C ratios at Beijing site, while the Gwangju site had the higher fractions of NH4+ and NO3- in ions, S, Br, As, Zn, and Pb in elements, acids, sugar/levoglucosan, and cholesterol in organic compounds, and CHO organic group with higher H/C and O/C ratio. Those differences suggest that fine particles at Beijing were affected by various combustion sources such as biomass burning, coal burning and traffics, and dust, and that the type of organics was dominated by primary (fresh) one, while biomass burning and traffics mainly affected the Gwangju site with secondary (aged) organics dominant. Three types of haze events (NO3-, Cl-, and K+-dominant event, EC, K+ and Cl--dominant event, and dust-dominant event) were observed at Beijing site with increased acids, PAHs with higher benzene rings, sugar/levoglucoan, and CHN organic group were observed. At Gwangju site, one type of haze event (NO3-, Pb, and K-dominant event) was observed with the increased sugar/levoglucoan, PAHs with higher benzene rings, CHON, CH, and CHNS organic groups compared to those during non-haze days. The increased emission strengths of various sources (biomass burning, coal burning, traffics, and dust) and secondary formation under stagnant conditions contributed to the winter haze events at the Beijing site. Also, the increased contributions of biomass burning and traffic sources and secondary formation under stagnant conditions contributed to the Gwangju haze events.