Spatiotemporal variations of air pollutants (O₃, NO₂, SO₂, CO, PM₁₀, and VOCs) with land-use types

Abstract

Abstract. The spatiotemporal variations of surface air pollutants (O3, 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 VOCs data at 9 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 O3 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 PM10, in commerce for NO2 and CO, and in greenbelt for O3, respectively. The concentrations of air pollutants, except for O3, were generally higher in big cities during weekdays while O3 showed its peak in suburban areas or small cities during weekends. The weekly cycle and trends of O3 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 VOCs-limited for ozone chemistry. The pollutants (NO2, SO2, CO, and PM10) except for O3 have decreased most likely due to the effective government control. The total oxidant values (OX = O3 + NO2) with the land-use types were analyzed for the local and regional (or background) contributions of O3, 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.