10th International Aerosol Conference
September 2 - September 7, 2018
America's Center Convention Complex
St. Louis, Missouri, USA

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High Abundance of Oxalic Acid in a Rural Atmosphere of Eastern Central India: Influence of Biomass Burning and Photochemical Processing

DHANANJAY KUMAR DESHMUKH, Manas Kanti Deb, Kimitaka Kawamura, Dharmendra Kumar Singh, Chubu University, Japan

     Abstract Number: 1158
     Working Group: Aerosol Chemistry

Abstract
Organic aerosols (OAs) are abundant in the troposphere and crucial for air quality and climate. The oxidation products of OAs are highly water-soluble and typically contain several functional groups. Fine aerosol samples (PM2.5) were collected at a rural site of eastern central India (Ambikapur: 23.12°N and 83.20°E) during March to June 2017. The samples were analyzed for water-soluble dicarboxylic acids (C2-C12), glyoxylic acid (ωC2), glyoxal (Gly) and methylglyoxal (MeGly) as well as organic carbon (OC), elemental carbon (EC) and water-soluble OC (WSOC). Oxalic acid (C2) was detected as the most abundant species followed by succinic (C4) or malonic (C3) acids. The temporal variability in concentrations of C2 diacid and related compounds was pronounced during the end of March to the middle of April when biomass burning episodes were dominant in eastern central India. The strong correlation of C2 with levoglucosan (r = 0.91) suggests that biomass burning was a major source of oxalic acid in eastern central India. Strong correlations of the C2 with saturated diacids (C3-C9: r = 0.81-0.96), ωC2 (r = 0.95), Gly (r = 0.92) and MeGly (r = 0.80) suggest their similar sources and formation processes and that oxalic acid in fine aerosols may be secondarily produced from these precursor compounds. The ratios of WSOC to OC (0.52-0.88) and C3 to C4 diacid (0.69-1.30) suggest that water-soluble organic aerosols (WSOAs) were photochemically processed during the campaign. Our results demonstrate that severe biomass burning and photochemical processing enhanced abundances of WSOAs in a rural atmosphere in eastern central India.