Urban and Industrial VOC Emissions in the Seoul Metropolitan Area and Surrounding Region during the KORUS-AQ Field Study

The Korea-United States Air Quality Study (KORUS-AQ) took place in May and June, 2016 to better understand air pollution in Korea. During the campaign 2650 whole air samples were collected aboard the NASA DC-8 aircraft and analyzed for more than 80 C₁-C₁₀ volatile organic compounds (VOCs), including alkanes, aromatics, alkenes, halocarbons and organic nitrates. Approximately 300 samples were collected at low altitude (< 1 km) over the Seoul Metropolitan Area (SMA), and ~20 downwind of the Daesan industrial facility southwest of Seoul. The Seoul and Daesan samples showed distinct chemical signals. Air in the SMA was rich in VOCs such as ethane, propane, toluene, ethyne and n-butane, reflecting a mix of source influences including natural gas, liquefied petroleum gas, vehicle exhaust and industrial solvents. Aromatics (e.g., toluene, xylenes) and alkenes (e.g., isoprene) were strong contributors to OH reactivity in the SMA. The Daesan plumes were rich in VOCs such as ethene, benzene and n-hexane, and at least 25 VOCs showed their highest mixing ratios of the mission in these plumes. Because some of the emitted industrial compounds are known carcinogens (e.g., benzene, 1,3-butadiene), more work is needed to assess potential long-term health effects for facility workers and local residents. Ongoing work includes further clarifying specific source influences in the SMA, assessing emission inventories and the contribution of individual VOCs to ozone production, and linking the airborne data to ground-based measurements.