The relation between meteorological and geochemical characteristics of precipitation associated with frontal depression was discussed on the basis of observation in Kanto district, in September 1978.
Concentration of chemical constituents in precipitation as well as electric conductivity was found to decreasewith time when the cyclone passed over this area. The rainout and washout coefficients were ranged from 10^-4 to 10^-3s-1 and 10^-5 to 10^-4s^-1 respectively. Little difference was found in washout coefficient between inland and coastal area. Cl/Na and Cl/SO₄ ratios in precipitation varied at different observation sites, and these were characterized by the amount of water vapor supply from the sea. The chlorine of inland areas were always higher than that of sea water. The reasons for the difference were considered.

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A study was made on the mechanism of the variation of pollutants concentration near the ground by emission, sedimentation and washout, during the period from midnight to early morning, when the effects of man-made emission and advection were both negligible. A model equation was developed to describe the temporal change in dust concentration during rainfall. The horizontal distribution of washout coefficient and quasi equilibrium concentration in the metropolitan area were determined. The washout coefficient of dust was related to the total amount of precipitation and was ranged from 10^-5 to 10^-4S^-1. The collection efficiency for raindrops with dust particles was estimated about 0.05, which was about 50 percent smaller than that expected from the model suggested by Chamberlain (1953). The reason for the difference was discussed.

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A direct injection type diesel engine, 3.6 1 of displacement, was operated on an engine dynamometer with flywheels. Exhaust gases were measured to simulate the transient NOx emission in terms of the emission under steady state conditions.
While NOx emission characteristics were investigated under steady state conditions, the NOx concentration during acceleration was compared with that under steady states on the basis of fuel consumption. Both of transient and steady concentrations almost coincided with each other during the acceleration of 1.53 km/h/s starting at 21.3 km/h, with the third gear position. Through the acceleration of 3.24 km/h/s, however, the steady state concentration showed higher value by 10% than the transient.
The frequency matrix distributions of engine load under ten kinds of actual traffic patterns were obtained as a function of engine revolution and torque. NOx emission were calculated by combining these distributions and steady state emissions. The estimated NOx emissions, having slightly lower value than the transient emissions, showed a good correlation with the transient emissions. It was found that classification of engine load was one of the most important factors.

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For ion chromatographic determination of anions in atmospheric aerosol, an efficient extraction method was developed. Eluent employed as extractant enabled some ions such as F-and Cl-to be determined, while these peaks, in case of water extraction, coincided with a negative peak probably due to water.
This extraction method was examined with atmospheric aerosol in the following points to be assured to its practical use:(1) reproducibility of each peak height, (2) extraction efficiencies of negative-ion-unaffected nitrate and sulfate, and (3) variation of ion concentration of extract in one-week storage.

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Recently the instrument using a piezoelectric microbalance method has been considered one of the most promising devices for measuring suspended particulates in atmosphere. This paper deals with the experimental results with regard to the methods of static and dynamic calibration for the mass sensitivity which is one of the fundamental characteristics of the instrument.
For the static calibration a thin aluminum film was coated in vacuum onto the oscillating sensor, and the mass of aluminum was calculated whereby the thickness of the film was measured by a multibeam interference microscope. The mass sensitivity was obtained from the frequency shift after coating and the mass of aluminum. As the result, the average mass sensitivity was 165.5 Hz/μg.
On the other hand the dynamic calibration was carried out using uranine aerosol generated by a nebulizer.The mass of uranine deposited onto the sensor was analyzed by the fluorophotometry. It was confirmed thatthe mass sensitivity was deviated from the regression line when the mass of uranine particles deposited onto thesensor came up to about 15μg. Within the range of the straight line the mass sensitivity was about 182.3 Hz/μg.Next the mass sensitivity was obtained by the filtration method. Using membrane filter of 0.1μm pore sizethe average mass sensitivity was estimated 178.8 Hz/μg.
The conclusion of the discussion about mass sensitivity is that the dynamic calibration method using uranineaerosol generated by a nebulizer is most appropriate and useful when the dust monitor using a piezoelectric microbalancemethod is operated for measuring the mass concentration of suspended particulates in atmosphere.

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Relationships between ozone absorption rate and degree of leaf in jury were investigated for attached leaves of tobacco, rice and corn plants.
The results obtained were as follows:
1) As for the decrease in apparent photosynthetic rate, Bel-W3 of two varieties of tobacco used for the experiment was extremely damaged by ozone, but the variety Hicks was less susceptible to ozone. Younger expanding leaves were very torelant to ozone, whereas middle or lower leaves were sensitive.
2) Ozone absorption rate of tobacco leaves calculated by the gas diffusion model was correlated linearly with that observed by assimilation chamber method. This correlation was not affected by the differences of varieties or leaf age.
3) The differences in ozone susceptibility between leaf ages were in no relation with leaf gas diffusion resistances. Threfore, it was concluded that it was not caused by ozone absorption rate of each leaf.
4) The degree of somatal closure during ozone fumigation was differed between species, varieties and leaf ages. The stomata of younger expanding leaves were more sensitive to ozone than that of the older leaves.
5) It was thought that the differnce in ozone susceptibility between two varieties of tobacco plants was considerably caused by the difference in gas diffusion resistance.

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