Sung-Nam Oh

Chemical composition and source signature of spring aerosol in Seoul, Korea

The measurement of atmospheric aerosol was made in Seoul during the spring of 1998. The objective of this study was to investigate the chemical characteristics of atmospheric aerosol with an emphasis on the effect of Asian dust. Total suspended particles (TSP) and particles smaller than 10 mm (PM10) were collected during March-

Chemical composition of atmospheric aerosols from Zhenbeitai, China, and Gosan, South Korea, during ACE‐Asia

[1] Studies were conducted as part of Asian Pacific Regional Aerosol Characterization Experiment (ACE-Asia) to characterize the major ion and elemental composition of aerosol particle samples collected at Gosan, an ACE-Asia supersite (GOS, Korea, total suspended particle or TSP samples) and at Zhenbeitai (ZBT, China, TSP and particles < 2.5 mm diameter or PM2.5 samples), a site closer to the sources for Asia dust. The concentrations of 24 elements in the ZBT PM2.5 samples were correlated with Al (an indicator of mineral dust), and the ratios of these elements to Al were similar to those in a loess certified reference material, but a second group of elements was enriched over crustal proportions most likely as a result of pollution emissions. The concentrations of various water-soluble (WS) cations (Na + ,K + ,C a 2+ ,M g 2+ ) also were generally well correlated with Al in both the ZBT and GOS samples, with the exception being WS K + at ZBT, where biomass burning may have had an effect. The percentage of calcium that was soluble approached 100% at ZBT versus � 60% at GOS, and the ratio WS Ca 2+ /Al also was higher at ZBT. The molar ratio of sulfate to WS Ca 2+ was � 0.1 at ZBT but increased to near unity at GOS, where the aerosol nitrate/WS Ca 2+ ratio was tenfold to hundredfold higher compared with ZBT, presumably because of anthropogenic influences. The observed differences in aerosol characteristics between sites can only be explained as the end product of different source contributions combined with complex processes involving gas-particle conversion, size-dependent fractionation, and aerosol mixing. INDEX TERMS: 0305 Atmospheric Composition and Structure: Aerosols and particles (0345, 4801); 0330 Atmospheric Composition and Structure: Geochemical cycles; 0365 Atmospheric Composition and Structure: Troposphere—composition and chemistry; 0368 Atmospheric Composition and Structure: Troposphere—constituent transport and chemistry; 9320 Information Related to Geographic Region: Asia; KEYWORDS: aerosol, biogeochemistry, atmospheric dust, air pollution, Asia

Monitoring of Acid Rain over Korean Peninsula

In order to investigate the temporal and spacial deposition characteristics of acid rain, five monitoring sites were set up in the central part of Korean Peninsula. Rainwater samples were collected by wet-only sampler from 1992 to 1997. The pH and conductivity values were measured and the major water soluble ionic components were also analyzed. Ion balance between anion and cation sum was calculated to check out the data quality of samples. The acidity of rainwater was influenced by the local sources and meteorological factors such as surface wind, moving path of storm, precipitation process, and so on. Backward trajectories were depicted to investigate the effect due to moving path of weather system. The rainwater shows strong acidity in winter and weak in summer. The pH and ion concentrations were highly dependent on synoptic weather system. In addition, we sampled fog/cloud at Mt. Sobaek (BAPMoN Station) from June to August 1995 and characterized the fog/cloud chemistry according to surface wind system of sampling site. The volume-weighted mean pH of fog/cloud samples is 4.39 at Mt. Sobaek during the sampling period.

Background monitoring and long-range transport of atmospheric CFC-11 and CFC-12 at Kosan, Korea

The background concentrations of atmospheric CFC-11 and CFC-12were monitored to assess their impact on stratospheric ozone depletion and global warming from September 1995 to March 1999 at Kosan, Korea, located at eastern margin of the Asian Continent. The concentrations of atmospheric CFC-11 at Kosan have decreased slightly, at a rate of –2.5 pptv yr-1, over the period in response to the Montreal Protocol. The CFC-12 mixing ratio at Kosan continues to increase in the atmosphere at a rate of 5.7 pptv yr-1 despite international regulations, because of its extreme atmosphere persistence. Recent trends ofthese two chlorofluorocarbons at Kosan, Korea were concordant with those of the northern hemispheric background monitored unitat Mauna Loa, Hawaii. The maximum seasonal mean mixing ratios of CFC-11 and CFC-12 at Kosan, Korea, were 270±4 pptv inthe spring and 538±9 pptv in the winter, and the corresponding seasonal minima were 267±7 and 529±12 pptv. This occurred in the summer and was due to southeasterlywinds from the northwestern Pacific Ocean. By performing a three-day isentropic backward trajectory analysis, it was shownthat air masses at Kosan, and with the exception of summer, mainly originated from central and northern China. In particular, the mixing ratios of these two contaminant speciesare closely related with their air mass trajectories.

Aircraft Measurements of Long-Range Trans-Boundary Air Pollutants over Yellow Sea

Airborne gaseous and particulate matter was measured above downwind ocean areas from China to the western region of the Korean peninsula for 10 days in the spring and autumn of 2005. The main objectives of this study were to investigate the spatial distribution of pollution in the ocean atmosphere between Korea and China, and to improve our understanding of acidic deposition in the Korean region in relation to processes affecting the transport of long-range trans-boundary air pollutants from China. The scientific payload on-board an ultra-light aircraft included measurements of the concentrations of SO 2 , NO x , O 3 and particulates. Meteorological profiles (air temperature, winds and humidity) were recorded simultaneously at a ground site. A six-manned aircraft (PA-31-350 type) served the flight scenarios of eight altitude and two azimuth levels for measuring gas fluxes and particulate depositions in the first intensive observation period (IOP) during April 15–25 and a second period during October 15–25, 2005. The overall mean concentrations of air pollutants in the atmospheric boundary layer were in the range 2.58–6.63 ppbv for SO 2 , 3.74–4.24 ppbv for NO x and 48.8–54.28 ppbv for O 3 in both observation periods. Measurements at different altitudes revealed that the pollutants were normally observed in high concentrations in the atmospheric boundary layer. However, the longitudinal measurements of SO 2 concentration showed higher values in areas over the Yellow Sea, though values decreased when approaching the Korean peninsula. Enhanced mass concentrations of SO2 were observed for altitudinal measurements when a strong westerly air stream occurred in the low level boundary layer from China to Korea. Aerosol number concentrations varied significantly in the range 32–4,640 ea/cm for aircraft measurements during both periods. The differences in NO x level between aircraft and surface measurements play an important role in the chemical form and size of particulate matter. 1 Meteorological Research Institute (METRI), Korea Meteorological Administration (KMA), 460-18 Shindaebang-dong, Dongjak-gu, Seoul 156-720, Korea 2 Global Environment Research Center, National Institute of Environment Research, Environmental Research Complex, Gyeongseo-dong, Seo-gu, Inchon 404-708, Korea