Yong Pyo Kim

Seasonal characteristics of ambient volatile organic compounds in Seoul, Korea

Abstract The measurements of C 2 –C 9 volatile organic compounds (VOC) were carried out at a site in Seoul, the capital of Korea from August 1998 to July 1999. Air samples were collected for 24xa0h in 6xa0l SUMMA canisters every 6 days. The canister samples were quantitatively analyzed by a GC/FID and GC/MS. The species with the highest mean concentration among the 70 identified was propane (7.8xa0ppb), followed by toluene (6.4xa0ppb) and ethylene (5.9xa0ppb). The high concentration of propane was mainly attributed to the emissions by liquefied petroleum gas (LPG) usage for cooking and heating, and butane fuel for transportation. The general trend of the seasonal variation shows higher concentrations in winter and lower ones in summer. This behavior was mainly caused by the variations of temperature, and resultant VOC source strengths, coupled with the variations of the mixing depth. According to the analysis of concentration ratios, the seasonal contributions of the major emission sources to the VOC concentrations were influenced by ambient temperature. Further, it was identified that the contributions by the use of solvents, natural gas, LPG, and butane fuel were closely related to the variations of consumption pattern according to seasons. Through the analysis of the concentration correlations between less reactive compound and highly reactive ones for summer and winter months, it was found that photochemical reactivity affects relative concentration of reactive compound.

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. n nThe 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. n nBackward 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.

Summertime characteristics of aerosol composition at Cheju Island, Korea

Abstract To understand the characteristics of air quality during summer in Northeastern Asia, an intensive field study had been carried out at Cheju Island, Korea during the period of 20 July to 10 August 1994. Total suspended particles and PM 2.5 particles were collected and their mass and ion concentrations were analyzed. Along with PM 2.5 , gaseous species were collected on impregnated filters. Also, another low volume sampler collected carbonaceous species analysis. The sampling period could be classified into two distinctive periods, with a highly polluted period between 20 July and 1 August and an unpolluted period between 2 and 10 August. During the polluted period, the mean non sea-salt sulfate concentrations in TSP and PM 2.5 were 16.6 and 13.4xa0 μ gxa0m -3 , respectively. Backward trajectory analysis showed that air parcels arriving at the sampling site during the former period were mainly from Korea and Japan while air parcels during the latter period were from the North Pacific Ocean. It was suggested that the air pollutant levels during the latter period could be considered as marine background concentrations in the region during summer.

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.

Seasonal variation of the C2–C9 hydrocarbons concentrations and compositions emitted from motor vehicles in a Seoul tunnel

Abstract The concentrations and compositions of C2–C9 hydrocarbons (HC) were measured in a tunnel at Seoul, Korea in winter, spring and summer, 2000. The average concentrations of ethylene, n-butane and acetylene were the highest species. Though the absolute concentrations of HC in the tunnel air varied significantly, the compositions of individual species were relatively constant over each season. The ratio of exhaust composition to fuel composition for benzene was >1, indicating that it is more abundant in the exhaust than that in the fuel. Consequently, to reduce benzene in vehicle emissions, it is necessary to control benzene-producing HC as well as benzene content in vehicle fuel. The most pronounced differences in the tunnel air among the three seasons were higher mass percentage for propane in winter and higher mass percentages of n-/i-butanes in summer. The amounts of butanes to the total HC in the tunnel air showed a positive relationship (R2=0.71) with the compositions of the butane-fueled vehicles to the total vehicles passing through the tunnel. It showed that butane vehicles are a major contributor to the high concentration of butanes in the tunnel air. Photochemical potential of C2–C9 HC measured in summer was evaluated by using the maximum incremental reactivity. For individual compounds, the contribution made by ethylene to the total specific reactivity was the highest, followed by propylene, 1,2,4-trimethylbenzene, toluene and m-/p-xylene. For five hydrocarbon classes, the contribution of alkenes to the total HC reactivity was the highest. It showed that alkenes were the most important contributor of photochemical ozone formation in the vehicle emissions. The most prominent differences between this study and other studies were higher mass percentages of n-/i-butanes and propane. The reason for this was the wide use of butane-fueled vehicles. Consequently, it was found out that the pattern of fuel usage is an important factor affecting the HC compositions in the vehicle emissions.

Visibility study in Seoul, 1993

Abstract Characteristics of visual air quality in Seoul were investigated during the fall of 1993. The total extinction coefficient, b ext the particle light scattering coefficient, b sp , and the particle mass size distribution were measured using a transmissometer, a nephelometer and a cascade impactor, respectively. Also PM1, PM3 and PM10 particles were collected and analyzed for their ionic concentrations. The smog characteristics were also estimated by using a Mie theory based model. Measured and estimated light extinction budgets agree to each other within 10%. According to measurements, the daily average b ext were 0.791 × 10 −3 and 0.297 × 10 −3 m −1 during the smoggy and clear period, respectively. Also b sp contributed 79.4 and 55.2% to b ext during the smoggy and clear period, respectively, showing that particle scattering is the dominant factor in light extinction during the smog episode. The major variables that affect smog phenomena in Seoul are mass loadings of fine particle fraction ( D p μ m), concentrations of sulfate and nitrate in fine particles, and relative humidity. The particle mass size distribution shows typical bimodal peaks, one of which is at about 0.8 μm and the other at about 5.0 μm of the mean diameter during both periods. Particulate sulfate and nitrate are more concentrated in the fine particle size fraction during the smoggy period than in the clear period. The effects of relative humidity are thought to influence the extinction and scattering efficiencies of particle species through changing the particle size.

Determination of domain for diagnostic wind field estimation in Korea

Abstract A diagnostic routine is applied to estimate wind fields for two coastal areas with mountains in Korea. The reliability of the predicted wind fields is assessed by calculating the maximum differences of wind speed and direction between two successive estimations by increasing the size of the estimation domain over the target domain. The differences decrease and stabilize after a critical increment to produce an optimum domain size used to estimate wind fields. Although a larger radius of influence and a larger grid size could increase the stability of convergence, they smooth the predicted wind field and decrease the resolution. The study also reveals that the estimated wind field shows larger differences from the wind field obtained with all stations available in the country, at higher mountains along the boundaries beyond which stations would be added if larger domains are employed.