Asian Journal of Atmospheric Environment (Sep 2020)

Semi-continuous Measurements of Water-soluble Organic Carbon and Ionic Composition of PM2.5 in Baengnyeong Island during the 2016 KORUS-AQ (Korea-United States Air Quality Study)

  • Seokwon Kang,
  • Gyutae Park,
  • Taehyun Park,
  • Jihee Ban,
  • Kyunghoon Kim,
  • Youngkyo Seo,
  • Jinyoung Choi,
  • Seokjun Seo,
  • Jinsoo Choi,
  • Min-Suk Bae,
  • Taehyoung Lee

DOI
https://doi.org/10.5572/ajae.2020.14.3.307
Journal volume & issue
Vol. 14, no. 3
pp. 307 – 318

Abstract

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This study characterized the water-soluble organic carbon (WSOC) and ionic components of PM2.5 (particles less than 2.5 μm in diameter) from April to June 2016, at Baengnyeong Island The study utilized a particle-into-liquid sampler (PILS) coupled with a total organic carbon (TOC) analyzer and ion chromatography (PILS-TOC-IC). The PM2.5 mean concentration in this study was 23.8±16.7 μg m-3, and the mean of WSOC concentration was 1.6±1.5 μg m-3. Ionic compounds increased by 3.8% in the period in which the air quality standard of PM2.5 (35 μg m-3) was exceeded because the concentration of ionic components increased due to generation by chemical reactions and emissions from a primary source in a nearby urban area. The wind direction and speed were mostly in the northwest and southwest directions and the higher concentration of PM2.5 was also shown in the same directions. In comparison with the previous study, the WSOC/OC ratio was 0.5±0.3 in Baengnyeong Island, which was higher than that at roadside and urban sites and lower than at the background site (Sweden, Aspvreten). It was considered that insoluble OC constituted a major proportion of primary OC that was emitted in urban areas, and the higher WSOC/OC ratios of rural and background sites were affected by inflow. The ratio of nitrate and sulfate in Baengnyeong Island was lower than urban areas in China in other studies, because of emitted aerosols from coal combustion or vehicle emission. The results indicate that Baengnyeong Island was affected by formation of secondary aerosols by chemical reactions and inflow from China as well as domestic emissions. The slope of H+Aersol/SO42- in Baengnyeong Island was 0.079, which was a result of neutralized particle acidity in ambient air. The molar ratio of nitrate and ammonium with sulfate in Baengnyeong Island showed ammonium-rich conditions because ammonium nitrate was increased to homogeneous reaction of ammonia and nitric acid in the gas-phase.

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