Spatiotemporal variations of PM2.5 and its precursors over South Korea during 2012-2017

Abstract:

Particulate matters with a diameter less than 2.5 micron (PM_2.5) are known to harm human health by causing diseases such as cardiovascular and respiratory problem. Sulfate (SO₄^2-), nitrate (NO₃^-) and ammonium (NH₄⁺) are known as the major constituents of PM_2.5. In South Korea, these constituents are observed hourly at six air quality intensive monitoring stations (Seoul, Bangryeongdo, Jung-bu, Honam, Yungnam and Jeju), operated by the Korean Ministry of the Environment (KMoE) and National Institute of Environmental Research (NIER). The concentrations of sulfur dioxide (SO₂), nitrogen dioxide (NO₂) and PM_2.5 are also observed hourly at AirKorea sites. In this study, we investigated the trends of PM_2.5 and its chemical composition during 2012-2017 focused in the six regions around the air quality intensive monitoring stations located. Additionally, we used Infrared Atmospheric Sounding Interferometer (IASI) ammonia (NH₃) total column, Ozone Monitoring Instrument (OMI) tropospheric NO₂ column and planetary boundary layer (PBL) SO₂ column density observations for the same analysis period to examine the results over the regional scale.

In the analysis using satellite observations, the column density of NH₃ showed increasing trend, whereas SO₂ and NO₂ showed decreasing trend. However, the results calculated from the in-situ observations showed the weak decreasing trend of SO₂ and increasing trend of NO₂. Furthermore, the differences in trends between stations were remarkable when using the in-situ observations. NH₄⁺ and SO₄^2- showed decreasing trends at all stations, and NO₃^- showed increasing trends except for Yungnam stations with limited data. According to these trends of constituents, the concentration of PM_2.5 decreased in the most region. Trends of precursor gas vary on the local scale and the regional scale, and the trends of the constituents of PM_2.5 are affected by both.