caa a22 4500 606200304 CHVBK 20210128100943.0 cr unu---uuuuu 210128e20151001xx s 000 0 eng 10.1007/s10653-014-9660-1 doi (NATIONALLICENCE)springer-10.1007/s10653-014-9660-1 In situ acidity and pH of size-fractionated aerosols during a recent smoke-haze episode in Southeast Asia [Elektronische Daten] [Sailesh Behera, Jinping Cheng, Rajasekhar Balasubramanian] The characterization of aerosol acidity has received increased attention in recent years due to its influence on atmospheric visibility, climate change and human health. Distribution of water soluble inorganic (WSI) ions in 12 different size fractions of aerosols was investigated under two different atmospheric conditions (smoke-haze and non-haze periods) in 2012 using the Micro-Orifice Uniform Deposit Impactor (MOUDI) and nano-MOUDI for the first time in Singapore. To estimate the in situ acidity ([H+]Ins) and in situ aerosol pH (pHIS), the Aerosol Inorganic Model version-IV under deliquescent mode of airborne particles was used at prevailing ambient temperature and relative humidity. The study revealed an increase in the levels of airborne particulate matter (PM) mass and concentrations of WSI ions for all size fractions during the smoke-haze period, which was caused by the trans-boundary transport of biomass burning-impacted air masses from Indonesia. A bimodal distribution was observed for concentrations of SO4 2−, NO3 −, Cl−, K+ and Na+, whereas concentrations of NH4 +, Ca2+ and Mg2+ showed a single mode distribution. The concentration of WSI ions in PM1.8 during the smoke-haze period increased by 3.8 (for SO4 2−) to 10.5 (for K+) times more than those observed during the non-haze period. The pHIS were observed to be lower during the smoke-haze period than that during the non-haze period for all size fractions of PM, indicating that atmospheric aerosols were more acidic due to the influence of biomass burning emissions. The particles in the accumulation mode were more acidic than those in the coarse mode. Springer Science+Business Media Dordrecht, 2014 Water soluble inorganic ions nationallicence Size-fractionated aerosol nationallicence Aerosol acidity nationallicence Smoke haze nationallicence AIM-IV nationallicence Biomass burning nationallicence Behera Sailesh Department of Civil and Environmental Engineering, National University of Singapore, 117576, Singapore, Republic of Singapore aut Cheng Jinping School of Environmental Science and Engineering, Shanghai Jiao Tong University, 200240, Shanghai, China aut Balasubramanian Rajasekhar Department of Civil and Environmental Engineering, National University of Singapore, 117576, Singapore, Republic of Singapore aut Environmental Geochemistry and Health Springer Netherlands 37/5(2015-10-01), 843-859 0269-4042 37:5<843 2015 37 10653 https://doi.org/10.1007/s10653-014-9660-1 text/html Onlinezugriff via DOI BK010053 XK010053 XK010000 Metadata rights reserved Springer special CC-BY-NC licence nationallicence 1 research-article jats NATIONALLICENCE NATIONALLICENCE NL-springer NATIONALLICENCE 856 40 https://doi.org/10.1007/s10653-014-9660-1 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Behera Sailesh Department of Civil and Environmental Engineering, National University of Singapore, 117576, Singapore, Republic of Singapore aut NATIONALLICENCE 700 1- Cheng Jinping School of Environmental Science and Engineering, Shanghai Jiao Tong University, 200240, Shanghai, China aut NATIONALLICENCE 700 1- Balasubramanian Rajasekhar Department of Civil and Environmental Engineering, National University of Singapore, 117576, Singapore, Republic of Singapore aut NATIONALLICENCE 773 0- Environmental Geochemistry and Health Springer Netherlands 37/5(2015-10-01), 843-859 0269-4042 37:5<843 2015 37 10653