Aerosols and gaseous samples were collected weekly by a four stage filter pack method in Nara City, a small inland city, during the period from July 1993 to June 1996, and at Mt. Ohdaigahara, a clean mountainous area during the summers and autumns from June 1995 to October 1996; the concentrations of soluble ionic components (SO42-, NO3-, Cl-, Na+, NH4+, K+, Ca2+ and Mg2+) of aerosols and gases (SO2, HNO3, HCl and NH3) were derived. The concentrations of aerosols and gases varied seasonally in Nara City; specifically, the SO2 concentration was high in winter and low in summer and the SO42- concentration of aerosols was high in summer and low in winter. HNO3, HCl and NH3 concentrations were high in summer and low in winter. On the other hand, NO3-, Cl- and NH4+ concentrations of aerosols were high in winter and low in summer. The ratio of concentrations of fine particle components such as SO42- and NH4+ at Mt. Ohdaigahara to those Nara City were not much lower than those of gases and the ratio was about 40% suggesting the long range transport of SO42- and NH4+. Average amount of dry deposition of SO42- and NO3- calculated by inferential method in Nara City were 0.80 and 1.6 mmol/m2/mo on bare ground, 0.96 and 1.7 mmol/m2/mo on agricultural land, 0.73 and 2.1 mmol/m2/mo on deciduous trees and 1.1 and 2.7 mmol/m2/mo on coniferous trees, respectively. Average SO42- and NO3- amount of deposition calculated by inferential method at Mt. Ohdaigahara were 0.10 and 0.41 mmol/m2/mo on bare ground, 0.15 and 0.42 mmol/m2/mo on agricultural land, 0.18 and 0.55 mmol/m2/mo on deciduous trees and 0.27 and 0.64 mmol/m2/mo on coniferous trees, respectively.
In order to know Asian dust particle distribution in the free troposphere, lidar measurements on scattering ratio (atmospheric aerosol density), depolarization ratio (nonsphericity of aerosol particles), and relative humidity were made in spring of 1994 at Nagoya using the Raman scattering effects. From discriminant analysis on those lidar data, six different type aerosols were identified; cloud particles, background free tropospheric aerosols, and four different groups of Asian dust particles (Kosa particles). The discriminant analysis of lidar return signal from atmospheric aerosols is useful way to identify Asian dust layers and to see mixing state of particle layers in the free troposphere.
Aerosol samples were collected by high-volume-samplers at 11 sampling points in Seoul, Taegu, Kwangju, Ulsan and Pusan, Korea during Kosa periods in 1995. The water soluble inorganic ions in the aerosol samples were measured and compared with those in rain water samples collected at Seoul, in 1995 and 1993. Calcium ion concentration was evaluated in two parts, one which actually contributed to the neutralization of rain and/or cloud water and the other which did not. The former should consist of carbonate, the latter, presumably, of sulfate and/or nitrate. The ratio of Ca2+ concentration derived from calcite to total Ca2+ concentration in rain water during Kosa periods, was estimated. As a result, it was suggested that almost of Ca2+ in the rain water was derived from CaCO3 in Kosa aerosols. On the other hand, it was considered that the Kosa aerosols collected on the ground had reacted with acidic materials on the filter. Sea-salt components were not correlated with Ca2+ derived from Kosa aerosols collected at sampling points located in the east side of Korea, but were correlated with that collected at sampling points located in the west side.