Spatiotemporal variations of air pollutants (O-3, NO2, SO2, CO, PM10, and VOCs) with land-use types

Abstract

The spatiotemporal variations of surface air pollutants (O-3, NO2, SO2, CO, and PM10) with four land-use types, residence (R), commerce (C), industry (I) and greenbelt (G), have been investigated at 283 stations in South Korea during 2002-2013, using routinely observed data. The volatile organic compound (VOC) data at nine photochemical pollutant monitoring stations available since 2007 were utilized in order to examine their effect on the ozone chemistry. The land-use types, set by the Korean government, were generally consistent with the satellite-derived land covers and with the previous result showing anti-correlation between O-3 and NO2 in diverse urban areas. The relationship between the two pollutants in the Seoul Metropolitan Area (SMA) residence land-use areas was substantially different from that outside of the SMA, probably due to the local differences in vehicle emissions. The highest concentrations of air pollutants in the diurnal, weekly, and annual cycles were found in industry for SO2 and PMPM10, in commerce for NO2 and CO, and in greenbelt for O-3. The concentrations of air pollutants, except for O-3, were generally higher in big cities during weekdays, while O-3 showed its peak in suburban areas or small cities during weekends. The weekly cycle and trends of O-3 were significantly out of phase with those of NO2, particularly in the residential and commercial areas, suggesting that vehicle emission was a major source in those areas. The ratios of VOCs to NO2 for each of the land-use types were in the order of I (10.2) > C (8.7) > G (3.9) > R (3.6), suggesting that most areas in South Korea were likely to be VOC-limited for ozone chemistry. The pollutants (NO2, SO2, CO, and PMPM10 except for O-3 have decreased, most likely due to the effective government control. The total oxidant values (OX = O-3 + NO2) with the land-use types were analyzed for the local and regional (or background) contributions of O-3, respectively, and the order of OX (ppb) was C (57.4) > R (53.6) > I (50.7) > G (45.4), indicating the greenbelt observation was close to the background.