The influences of fog generation/evaporation on the properties of aerosol particles were investigated through the analyses of gas, aerosol particles and droplets off the coast of East Hokkaido in Japan during the foggy season (April and July, 2001) and non-foggy season (October, 2000 and January, 2001). Case study of a single fog event indicates that 1) SO₂, NH₃ and HNO₃ gas were dissolved in droplets above 2μm in diameter during a fog event and 2) Na⁺ concentration in fine particles (<2μm) increased during evaporation stage suggesting droplet splashing.
Particle fractions (PF) and fine particle fractions (FPF) in all seasons were analyzed to evaluate the influences of fog on aerosol particles. In foggy season, the average PF of SO₄^2-and NH₄⁺were higher than those of non-foggy season indicating that the dissolution of gas under foggy generation. On the other hand the average FPF of Na⁺ in foggy season were 3 times as large as non-foggy season suggesting that droplets splash during the evaporation of fog droplets. From these results it is concluded that fog cycles play roles in seasonal variation of aerosol chemistry in this area.

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The denuder/filter-pack sampling system has been used for three years since September 1998, in order to measure daily concentrations of nitrate, chloride and ammonium in the gas and fine-and coarse-aerosol phases in Tokyo.
Total nitrate concentration does not vary seasonally, but its partitioning ratio shows remarkable seasonality with increases in the gas phase in summertime and in the fine-aerosol phase in wintertime. Total chloride concentration is high in wintertime due to non-sea-salt chloride in the fine-aerosol phase. Total ammonium concentration varies a little with season as well as its partitioning ratio.
Those measurements are analyzed for the partitioning of nitrate, ammonium and chloride between the gas and fine-aerosol phases. It was found that estimates based on equilibrium reactions in a multi-component system are very comparable to measured concentration products of gaseous components. This suggests that the gaseous components are in equilibrium with corresponding components in internally-mixed fine aerosol. In wintertime, however, the concentration products are also well predicted by equilibrium coefficients in a single component system, which implies that external mixture of fine aerosol can be applied.

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Laser-Induced Fluorescence (LIF) spectra from peanut leaves excited by UV laser were measured. The LIF spectra were changed by both the ozone exposure and the ultraviolet irradiation from UV-B fluorescent lamp immediately. The characteristics of the LIF spectra changes into the ozone and the ultraviolet stresses were quantified by the fluorescence ratios F685/F530 (red/green) and F740/F685 (far-red/red).
For the ozone exposure, F685/F530 ratio decreased in proportion to the logarithm of the exposure time as well as in proportion to the ozone concentration. F740/F685 ratio increased during the first hour then decreased gradually. For the ultraviolet irradiation, F685/F530 ratio decreased in proportion to the ultraviolet fluence, while F740/F685 ratio increased in proportion to the irradiation time. By clarifying the characteristics of LIF spectra changes in plant leaves, it is thought that the early detection of any damage and stress factor specifics becomes possible.

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In order to predict the concentration at the leeward side of the canyon (C_L), therelation between parameter K in the SRI street canyon model and the rooftop wind velocity was investigated by using the field data of air tracer dispersion experiment.
The major conclusions are as follows:(1) When the rooftop wind direction was perpendicular to the road, parameter K increased with increasing rooftop wind velocity.
(2) The relation between K and rooftop wind velocity (U_H) was expressed well by the following equation,
K=α·[(U_H+0.5) (x²+z²) ^0.5+2]/(δ_w·L) where a is constant, x and z are the horizontal and the vertical distances of the receptor from the line source, respectively, aw is the standard deviation of the vertical wind velocity and L is the width of the canyon.

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[in Japanese]

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[in Japanese]

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[in Japanese]

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