We studied multiple effects of sulfur dioxide and hydrogen fluoride on leaf damage, weight of grain, panicles per hill, spikelets per panicle and percentage of ripened grains of rice plant.
The correlation coefficient between ambient concentrations of sulfur dioxide measured as sulfur oxides (SO_x) and sulfur contents in leaves ranges from 0.713 to 0.910. That between the percent leaf damage and the sulfur and fluorine contents in leaves ranges from 0.807 to 0.978.
The panicles per hill is significantly affected by hydrogenfluoride than sulfur oxides. The spikelets per panicle have been affected slightly while the 1000-grain-weight has not been affected. It is suggested that the reduction of rice yield under polluted field conditions may have been caused by the diminution of panicles per hill and the percent fertility rather than by that of spikelets per panicle and the grain weight.

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In order to clarify the diffusion of air pollutants in Tokyo metropolitan area, where middle and high buildings are concentrated, air tracer (SF₆) dispersion experiments were conducted at night time in winter. Two cases were under windy conditions and the other was under calm condition. Following conclusions were obtained through the analysis of these data:
(1) The highest concentration of the tracer gas in the vertical direction was not at the source height, but was at the height of a little higher than the average height of the middle-sized buildings.
(2) The advection direction of tracer clouds was consistent with the wind direction at 50 m height, which was a little higher than the average height of the middle-sized buildings, and the advectin velocity was 20-30% of the wind speed at 50 m height.

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This survey is a part of the study to assess the health effects of automobile exhaust for schoolchildren living along major arterial roads with heavy traffic. Indoor nitrogen dioxide (NO₂) concentrations in both winter and summer were measured in homes of schoolchildren attending eight primary schools in Chiba Prefecture. Five schools were located in urban cities and near major arterial roads, and the others were in rural cities with clean air.
While indoor NO₂ concentrations ranged widely among homes, the large variation was due to ambient NO₂ levels, type of heating apparatus, structure of houses, and environmental tobacco smoke. Particularly the use of unventilated heater remarkably increased indoor NO₂ concentrations in the winter. With regard to distances from arterial roads, indoor NO₂ concentrations were higher in homes located within 50 m from the roadsides than in those over 50 m, but the difference was not statistically significant.
The mean of indoor NO₂ concentrations in homes of each school was calculated according to distances from the roadsides, and its relationship to ambient NO₂ level measured at the nearest general monitoring station was investigated. In homes located over 50 m from the roadsides, indoor NO₂ concentrations were significantly related to ambient levels in the summer, and to ambient levels and the percentage of homes using unventilated heater in the winter. However, in homes located within 50 m from the roadsides, indoor NO₂ concentrations were unrelated to ambient levels in both seasons. Indoor NO₂ concentrations in homes along arterial roads, and their affecting factors should be studied further.

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Combinations of 7 adsorbents and 6 extractive solvents were evaluated with collection and extraction efficiencies for measuring 43 pesticides in air by GC/MS. Dichloromethane and acetone were easier to extract such pesticides from the adsorbents. Collection efficiencies of the pesticides on activated carbon fiber paper and ORBO-49P were higher average values and most of them were over 60%. From the results of principal ingredient analyses, the extraction efficiencies show that the 1st factor is characteristics of solvents. Factors of collection efficiencies were considered to be concerned with sampling time and characteristics of the adsorbents. So it is concluded that dichloromethane extraction from activated carbon fiber paper and acetone extraction from ORBO-49P are effective for measuring these airborne pesticides.

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Methane flux from a rice paddy, using a chamber method, was measured at Fukuoka Agricultural Research Center during a cultivation period, from June to October in 1990. Methane flux increased since two weeks of rice-transplanting, and was in the range of 10-20 mg CH₄/ m²/ hr when the paddy was flooded. However, the flux decreased less than 1mg CH₄/ m²/ hr after the first drainage of flooding water at the end of July. Afterwards, the flux stayed low at the same level, because flooding and drainage were alternatively repeated in the rice paddy so that the soil in the paddy was prevented from being anaerobic. Some physical parameters, such as temperatures of the ambient atmosphere, flooding water, paddy soil, and oxidation-reduction potential (Eh) of the paddy soil were measured simultaneously. Especially, Eh showed a strong correlation wi th the observed change of the methane flux, i. e. the flux was high when Eh was lower than -200 mV, which indicated that the soil was in a highly reduced condition. Methane flux did not show any significant diurnal variation.
From the observed results, average methane flux for the cultivating period is calculated as 3.3 mg CH₄/ m²/hr (0.08g CH₄/ m²/ day), and average flux for the flooding period is to be 7.4 mg CH₄/ m²/ hr (0.18g CH₄/ m²/day). The total methane flux from the rice paddy is estimated to be about 9g CH₄/ m²/period by integrating the observed methane flux during the cultivating period.

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The multivariate analysis was applied for our better understanding of the relationship between meteorological factors and the major ion concentrations in rain and snow depositions. The analyzed wet deposition was collected on each event basis at two sampling stations placed in Muroran and Morino, southwest Hokkaido from July, 1990 through December, 1992. Because one of the most serious pollutant species has been hitting our environment, the variation in content of non-seasalt (nss) SO₄^2- ion in wet depositions was investigated by the quantification method of first type with respect to meteorological factors. It is found that the analyzed meteorological factors contribute to the concentration of nssSO₄^2- in the following ascending order: season, wind direction, back trajectory course and the amount of deposition. The analysis for back trajectory course by this particular method also revealed that a portion of nssSO₄^2- contents orginated from industrial pollutant emissions from geographical sources, viz in southeast China and east Russia. It is suggested that the wind direction can be utilized as an indicator to identify local sources of pollutant species in wet precipitation. Thus, the employment of multivariate analysis is more effective than a simple mathematical analysis in order to see the exact relationship between the conentration of a given ionic species in wet deposition and the meteorological factors.

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