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Chemical Characteristics of Aerosols in Coastal and Urban Ambient Atmospheres
Kwangyul Lee1, Jiyeon Park1,3, Minsoo Kang1, Dohyung Kim1, Tsatsral Batmunkh1, Min-Suk Bae2, Kihong Park1
1 National Leading Research Laboratory (Aerosol Technology and Monitoring Laboratory), School of Environmental Science and Engineering, Gwangju Institute of Science and Technology (GIST), Buk-gu, Gwangju 61005, Korea
2 Department of Environmental Engineering, Mokpo National University, Muangun, Jeollanamdo 58554, Korea
3 Department of Environmental Engineering Sciences, University of Florida, FL 32611, USA
- A clear difference in organics types was found between coastal and urban atmospheres.
- Air-mass dependent chemical characteristics were observed at both sites.
- Long-range transported aerosols played an important in chemical properties of aerosols.
Chemical characteristics of aerosols (PM1 (on-line measurement) and PM2.5 (off-line measurement) were investigated in coastal and urban atmospheres. Organics were the most dominant species in PM1 at both sites, exhibiting little difference in the relative fractions of chemical constituents in PM1 (organics, sulfate, black carbon (BC), nitrate, ammonium and chloride) between two sites. However, a clear difference in the types of organics was found between the two sites. The fraction of oxidized (aged) organics was much higher at coastal site than at urban site. The nitrate fraction significantly increased at both sites in PM2.5 compared with that in PM1, suggesting that a significant amount of nitrate exists at particle sizes of 1 µm–2.5 µm. Additionally, the aerosols observed at coastal site were acidic. At both sites, photochemical activity played an important role in enhancing sulfate and oxidized organics in the afternoon, thereby overcoming the dilution effect. More distinct diurnal patterns were observed for nitrate, BC and organics at the urban site compared to the coastal site. Chemical characteristics also varied with different air masses. The highest PM concentration was associated with the northwest continental air mass (the air mass passed over heavy industrial areas before arriving at the site and moved slowly compared to other air masses). Three PM events (sulfate-dominant versus organic-dominant) were observed during the sampling periods and were considered long-range transport (LTP) events. The water-soluble organic carbon (WSOC) and oxidized organic contents significantly increased during LTP events, suggesting that organics were highly aged during transport.
Urban; Coastal; PM2.5; Chemical characteristics; Aerosol mass spectrometer.