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Sources of High Sulfate Aerosol Concentration Observed at Cape Hedo in Spring 2012

Category: Air Pollution Modeling

Volume: 19 | Issue: 3 | Pages: 587-600
DOI: 10.4209/aaqr.2018.09.0350
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Syuichi Itahashi 1,2, Shiro Hatakeyama3,4,5, Kojiro Shimada6, Akinori Takami7

  • 1 Environmental Science Research Laboratory, Central Research Institute of Electric Power Industry, Abiko, Chiba 270-1194, Japan
  • 2 Department of Marine, Earth, and Atmospheric Sciences, North Carolina State University, Raleigh, NC 27695, USA
  • 3 Global Innovation Research Organization, Tokyo University of Agriculture and Technology, Fuchu, Tokyo 183-8509, Japan
  • 4 Graduate School of Agriculture, Tokyo University of Agriculture and Technology, Fuchu, Tokyo 183-8509, Japan
  • 5 Center for Environmental Science in Saitama, Kazo, Saitama 347-0115, Japan
  • 6 School of Creative Science and Engineering, Waseda University, Shinjuku, Tokyo 169-8555, Japan
  • 7 National Institute for Environmental Studies, Onogawa, Tsukuba, 305-8506, Japan

Highlights

High concentrations of SO42– were found during spring 2012 at Cape Hedo.
SO42– sources for these episodes were estimated by the tagged tracer method.
Volcanoes had a large effect in March.
Long-range transport from China was dominant in April.
Injection height was important for better model prediction of volcano sources.


Abstract

Intensive observation campaigns approximately 1 week long were conducted periodically from March 2010 to November 2015 at Cape Hedo, Okinawa, Japan. The maximum daily mean sulfate aerosol (SO42–) concentrations surpassed 15 µg m–3 in spring 2012. In this study, source apportionment for these high concentrations was conducted using an air quality model with the tagged tracer method, and the main source was identified as volcanoes in March and as anthropogenic emissions from China in April. In March, the prevailing northerly wind transported a volcanic SO2 plume with a low conversion ratio to Cape Hedo. The impacts of 15 volcanoes in Japan were estimated, and a substantial impact from Sakurajima, which accounted for more SO2 than anthropogenic emissions from Japan, was found. Because the model had difficulty capturing the highest concentration, three sensitivity simulations were performed to consider the uncertainty of the volcanic SO2 emission amounts and injection heights, revealing the importance of the injection height in addition to the SO2 emission amount. Throughout April, contributions from anthropogenic emissions from China were found; hence, this source was further divided into 31 provincial scales. Shandong and Jiangsu Provinces, which are the first and seventh largest emission sources in China, respectively, were identified as significant sources at Cape Hedo. These sources showed day-to-day variation in their contributions, and the highest contribution from Shandong Province occurred on April 23, whereas that from Jiangsu Province occurred on April 22.

Keywords

Air quality model Source apportionment Tagged tracer method East Asia Cape Hedo Atmosphere and Aerosol Monitoring Station (CHAAMS)


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