Kil-Choo Moon

Seasonal variation of ionic species in fine particles at Qingdao, China

Totally nine measurement campaigns for ambient particles and SO2 have been conducted during the period of 1997–2000 in Qingdao in order to understand the characteristics of the particulate matter in coastal areas of China. The mass fractions of PM2.5, PM2.5−10 and PM>10 in TSP are 49%, 25% and 26%, respectively. The size distribution of particles mass concentrations in Qingdao shows bi-modal distribution. Mass fraction percentages of water-soluble ions in PM2.5, PM2.5−10 and PM>10 decreased from 62% to 35% and 21%. In fine particles, sulfate, nitrate and ammonium, secondary formed compounds, are major components, totally accounting for 50% of PM2.5 mass concentration. The ratios of sulfate, chloride, ammonium and potassium in PM2.5 for heating versus non-heating periods are 1.34, 1.80, 1.56 and 1.44, respectively. The ratio of nitrate is 3.02 and this high ratio could be caused by reduced volatilization at lower temperature. Sulfate concentrations are higher than nitrate in PM2.5. The chemical forms of sulfate and nitrate are probably (NH4)2SO4 and NH4NO3 and chloride depletion was observed. Backward trajectory analysis reflected possible influence of air pollutant transport to Qingdao local aerosol pollution.

Concentrations of volatile organic compounds in an industrial area of Korea

We measured and analyzed daily mean concentrations of volatile organic compounds (VOC) at Ulsan industrial and downtown sites from 3 to 8 June 1997. The industrial site is situated at the boundary of a petrochemical complex and the other is at downtown area in Ulsan. At each site, we collected ambient air samples in passivated stainless-steel containers by using constant flow samplers and analyzed them by a GC-FID. At Ulsan industrial site, the concentrations and their daily variations of total VOC were higher than those at the downtown site. The concentrations of oxygenated hydrocarbons were the highest among seven hydrocarbon groups at both sites. The fraction of C2–C5 light hydrocarbon concentrations to C2–C9 hydrocarbons at Ulsan industrial site was higher than that in other industrial areas. It suggests that fugitive emissions of light hydrocarbons in Ulsan industrial areas might be higher than those of other industrial areas. Under favorable wind conditions, the influence of industrial emissions of VOC on the downtown hydrocarbon levels was observed.

Concentrations of carbonaceous species in particles at Seoul and Cheju in Korea

Concentrations of elemental carbon (EC) and organic carbon (OC) in particles at Seoul and Cheju Island, Korea were observed in 1994. PM10 and PM2.5 were collected by a modified SCAQS (Southern California Air Quality Study) sampler from Seoul during June 1994 and PM2.5 were collected by a low-volume sampler at Cheju Island during July and August 1994. The selective thermal oxidation method with MnO2 catalyst was used for analysis. The EC concentrations from Seoul were higher than those at Los Angeles, USA during the SCAQS study while the OC concentrations were comparable to those during the SCAQS study. At Cheju Island, the OC concentrations were higher than those at other clean areas in the world but the EC concentrations were lower than or comparable to those at other clean areas in the world. The OC to EC ratios of Seoul suggest that the carbonaceous species are mostly from primary emission sources. In Cheju, during July 1994 air pollutant levels were high and it was suggested that atmospheric transformation/transport of organics and biogenic emissions were main sources of carbonaceous species in particles. The carbonaceous species levels were low during August 1994 and it was suggested that the levels could be considered as marine background concentrations in the region during summer.

Fine particle measurements at two background sites in Korea between 1996 and 1997

Abstract Five intensive field measurements were carried out at two background sites in Korea; Kosan and Kangwha during spring, fall, and winters of 1996 and 1997 to investigate the characteristics of long-range transport of air pollutants in northeastern Asia. Fine particles (PM 2.5 ) were collected by low-volume samplers and the concentrations of major ions, organic and elemental carbons, and nitric acid were quantified. The concentrations of anthropogenic species in PM 2.5 measured at both sites were generally higher than those at other background areas, Nagano, Japan and San Nicolas Is., USA due to continental outflow of air pollutants, but lower than those at an urban background site, Qingdao, China. The major components of PM 2.5 were sulfate, organic carbon (OC), and ammonium for Kosan and sulfate, OC, ammonium, and nitrate for Kangwha. The major fractions of sulfate at both sites are non-sea-salts (nss) sulfate. Based on the relationship among major anthropogenic species, analysis of the nss sulfate to total nitrate molar ratios, and backward air parcel trajectories, it was found that fine particles measured at both sites during the measurement periods are mainly coming from China. At Kosan, the concentrations of anthropogenic species were higher when air parcels were coming from southern China than when air parcels were from northern China. At Kangwha, however, the differences of the concentrations were not statistically significant since most air parcels were from northern China and local effects are prominent.

Organic and elemental carbon in fine particles at Kosan, Korea

Abstract Concentrations of elemental carbon (EC) and organic carbon (OC) in fine particles at Kosan, Cheju Island Korea were observed during seven intensive measurement periods between 1994 and 1997. PM2.5 were collected on a pre-fired quartz filter by a low volume aerosol sampler and EC and OC concentrations were quantified by the selective thermal oxidation method with MnO2 catalyst. The OC concentrations were higher than those at other background areas in the world but the EC concentrations were lower than or comparable to those at other background areas in the world. The OC and EC concentrations varied depending on air parcel trajectories, higher concentrations were observed when air parcels were from southern China than those from northern China. Regional marine background levels of EC and OC were observed when air parcels were from the North Pacific. Except summer, the OC and EC concentrations show good relationship, implying both OC and EC had the same emission/transport characteristics outside of Cheju Island. Their relationships were poor during August 1994 and July 1995 when air parcels were from the North Pacific. It might be due to the biogenic emissions of OC around the site during summer.

Visibility trends in Korea during the past two decades.

Abstract Temporal trends and spatial distributions of visibility measured by the human eye over 60 stations in Korea between 1980 and 2000 are analyzed and discussed. Generally, visibility is lowest on winter mornings and highest on summer afternoons throughout Korea. Visibility in Seoul is now in an increasing trend while it has decreased nationwide, especially in clean coastal areas. Spatial distribution of visibility in the 1990s was related negatively to that of relative humidity (RH). However, visibility generally decreased despite an overall decrease in RH throughout the country. Air pollutants should have played a role in this dissonant variation, particularly in relatively clean areas and on summer afternoons. It was interpreted that the visibility increase in major metropolitan areas, including the greater Seoul area, in the 1990s was caused mainly by the reduction in pollutant emissions by rigorous government policy. But the effect of the emission reduction was manifested with decreasing RH.

Characteristics of TSP and PM2.5 measured at Tokchok Island in the Yellow Sea

Abstract Various air pollutants have been measured at Tokchok Island since April 1999. The Island is situated in the Yellow Sea, about 50 km from Incheon. This study was undertaken to help understand the levels of air pollution and their distribution characteristics over the Yellow Sea. The mass concentrations and chemical compositions, of total suspended particulates (TSP) and fine particles (PM2.5), measured up until March 2000 are discussed in this paper. The overall average mass concentrations for TSP and PM2.5 were about 37.2 and 18.7 μg m −3 , respectively, which were similar to, or lower than, those observed at other background sites in Kangwha and Taean, Korea. However, they are much lower than those observed at Qingdao in China. The low mass concentrations and major anthropogenic ion concentrations in aerosols collected at Tokchok Island show that local sources are not dominant. The estimated average fractions of non-sea-salt (nss) sulfate to total sulfate concentrations of TSP and PM2.5 are >98% for each. This would suggest that sulfate is mainly affected by anthropogenic sources. If we consider the average mass ratio of PM2.5 to TSP, the mass fractions of anthropogenic species to PM2.5, and the molar ratio of nss sulfate to total nitrate, it may be possible to infer that a part of the anthropogenic species measured at Tokchok Island is transported from China. The characteristics of neutralization of nss sulfate, and the particle sizes of major ions, are also discussed.

Carbonaceous species in fine particles at the background sites in Korea between 1994 and 1999

Abstract Organic carbon (OC) and elemental carbon (EC) in fine particles (PM2.5) at two background sites, Kosan and Kangwha in Korea were measured during intensive field studies between 1994 and 1999. Fine particles were collected on pre-fired quartz filters in a low-volume sampler and analyzed using the selective thermal oxidation method with MnO2 catalyst. The OC and EC concentrations at Kosan located at western tip of Cheju Island in southern Korea are lower than those at Kangwha located at western coastal area in mid-Korean peninsula. Still, the OC concentrations at Kosan are generally higher than those at other background areas in Japan and USA. The EC concentrations at Kosan are lower than or comparable to those at other background areas. The total carbon (TC, sum of OC and EC) to EC ratio values at both sites were higher than those at other background areas in Japan and USA. At Kosan, the OC and EC concentrations when air parcels were from southern China were higher than those when air parcels were coming from northern China. However, at Kangwha, the differences were statistically not clear since most air parcels were from northern China. Except when air parcels were from the North Pacific during summer, the OC and EC concentrations are well correlated indicating that both OC and EC share the same emission/transport characteristics. From the gaseous hydrocarbon data and the OC and EC relationship, it was found that during summer local biogenic emissions of OC might be significant at Kosan.

Smog Chamber Measurements

Photochemical smog still remains an issue in urban areas. Various smog chambers have been used to examine atmospheric processes of the formation of ozone and secondary organic aerosols. Prior to conduct smog chamber experiments, spectrum and intensity of light sources and chamber wall effects need to be characterized. Experimental techniques such as light intensity control, temperature control, comparison of twin chambers are also required to obtain more reliable and useful data from smog chamber experiments. Smog chamber experiments can be classified into indoor and outdoor chamber studies or VOCs–NOx–air mixture and ambient air experiments. Some typical and important investigations from previous smog chamber experiments are introduced here. Finally, applications of smog chamber experiments are demonstrated for diesel exhaust and indoor air chemistry.

Determination of Non-Methane Hydrocarbon Emission Factors from Vehicles in a Tunnel in Seoul in May 2000

Measurements of non-methane hydrocarbons (NMHC) were performed at the entrance and exit of the Sangdo tunnel to estimate emission factors (EF) of NMHC from vehicles in May 2000. About 50 species were analyzed by a combined GC/FID and GC/MS system. Ethylene was the most abundant compound, followed by n-butane and acetylene, respectively. Based on the measurement data, the real world vehicular EF in Seoul was estimated. The highest EF value was 89.8 mg (veh-mile)-1 for n-butane, followed by ethylene and toluene.