The atmosphere around plants in the field usually contains several phytotoxic air pollutant. How these pollutants interact and affect the expression of injury on plants are very important, but a clear explanation has not been made.
This paper summerized the Japanese and foreign literatures on the effects of combined pollutants on plants.
1) Acute effects
Tobacco plant exposed to combination of SO₂ and O₃ showed remarkably synergistic effect on injury expression, but on the other plant the general tendency of combined effect was not evident.
Examples of synergism of SO₂ and NO₂ on plant was reported by-Tingey et al.(1971), however, there were few reports which confirmed synergistic effect of these combination.
Combined treatment of O₃ and PAN (Peroxyacetyl nitrate) on plant showed antagonistic effect of injury expressions in almost of all work.
2) Chronic effect
There were few reports which showed synergistic effect of SO2 and O₃ on plant growth and yield.
Ashenden et al.(1978, 79) reported synergistic effect of SO₂ and NO₂ on grasses.
There were very few reports which showed synergistic effect of combined treatment of SO₂ and HF.

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A practical method to consider an internal boundary layer (IBL) was developed to simulate the atmospheric dispersion of airborne effluent from a nuclear power plant which is located in the coastal region. This model consists of a mass-consistent wind field model with a variational method and a random-walk model to solve an advection-diffusion equation numerically. A modeling of IBL is performed by a set of three vertical turbulence layers which are equivalent to a completely adjusted layer to the ground, a transition layer whose turbulence is intermediate and a stable layer above IBL. The difference of three turbulence layers is characterized by horizontal and vertical diffusivities.
For the validation, calculated results were compared with field tracer experiments performed in Tokai-mura, Ibaraki-ken, Japan and the results showed that this model could present the fumigation well. As another validation, this model was compared with Ryons and Cole model which was often used as a fumigation model.

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Our previous papers presented the practical system to predict pollutant dispersion in a complex terrain. The study included the field experiments conducted in such region.
At first the field of wind flow in an area concerned is determined by a modified potential flow model. Second the ground level concentration is calculated by the modified plume model.
This paper presents the effect of various parameters in the wind field model on calculated wind field in comparison with the observation of the experiments in Tochigi area.
As a result of analysis, the desirable parameter of power law is estimated to be 0.14 and the pseudo-resistance parameter 1.0 to calculate the wind field in neutral condition in Tochigi area by the proposed model. Though the effect of wind boundary condition seems to be significant, the proposed model is found to be applicable when the above mentioned parameters are determined properly.

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The measurement of non-methane hydrocarbon components was carried out over the southern part of Kanto district by use of aircraft in July 22nd and 23rd of 1982. The data were analyzed in relation to the concentration and the correlation of each hydrocarbon components, and OHREAC which was one of a photochemical reactivity index of mixed hydrocarbons described by Uno et al.
The concentration and OHREAC both showed very high value over the sourthern part of Saitama prefecture and Tokyo metropolitan area in both days. The hydrocarbons, which showed high concentration, were toluene, ethylene, acetylene, propane, n-butane, ethane, benzene and so on in both days. The correlationship between hydrocarbon components and ethane was fairly good except very high reactivity hydrocarbons like butenes. Especially, weak reactivity substances like butanes, propane and so on showed very good correlation with ethane.
As the result, in this research, it was clarified that the concentration of non-methane hydrocarbon components and OHREAC showed the high level over the polluted industrial area, and there were fairly good correlationship between hydrocarbon components except very high reactivity substances, which that was thought due to the progress of photochemical reaction.

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Analysis of sequential precipitation samples collected at 9 stations located in the Western Japan were carried out during a period from October to November 1979. Samples were taken by automatic, sequential samplers and measured for pH, conductivity and the concentration of major ions. The source and transport of SO₄^2-in precipitation was discussed on the data obtained.
Temporal variations in the concentration, enrichment factor and wet deposition of SO₄^2- were divided into “initial stage” and “stable equilibrium stage” for convenient consideration. A rapid almost exponential decrease in the concentration of SO₄^2- and other ions except H⁺ was observed during the initial stage when the cyclone passed over the station area. The time constant of this attenuation process was within the rage of 70 to 150 minutes. Wet deposition of the initial stage was relatively small, the stable equilibrium stage was considered to contribute an important role on the total wet deposition of SO₄^2- associated with a single event of frontal depression. SO₄^2-of the stable equilibrium stage was not the oceanic source because the enrichment factor of SO₄^2-was larger than 1. Meteorological analysis suggested that SO₄^2-of the stable equilibrium stage was the anthropogenic sulfur compound, which had been scavenged by precipitation elements in the below cloud layer.

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In order to develop a method for detecting air pollution by using bryometer, the effects of SO₂ and NO₂ alone and in combinations on the germination and protonemal growth of the moss spores were investigated. The spores of four moss species of Pylaisia brotheri, Entodon challengeri, Fabronia matsumurae and Venturiella sinensis on agar culture medium were continuously exposed to SO₂ (0.05-0.20 ppm), NO₂ (0.025-0.20 ppm) and their mixtures for 7-40 days.
The order of sensitivity of their spores for SO₂, NO₂ and their mixtures was P. brotheri >E. challengeri>F. matsumurae>V. sinensis, which was in agreement with that of their gametophores usually observed in the field.
The rates of spore germination and protonemal growth of F. matsumurae obtained by using a bryometer were compared with those expected from the results of gas exposure experiments. The observed rate, which was approximated with the expected rate in winter, differed from the expected one clearly in autumn. It was suggested that the germination and protonemal growth of the spores might be affected with not only SO₂ and NO₂ but with other pollutants such as photochemical oxidants.

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As an approach to the modeling of formation and diffusion processes of photochemical air pollution, one type of trajectory model has been developed. The cell traveling along the trajectory has a three layered structure with an upper limit at 500 m height. The chemical and photochemical reactions in each layer and the vertical eddy diffusions through every interface and the top boundary are calculated during the travel.
Some parameters, such as vertical diffusion coefficient, background concentration of hydrocarbon and deposition velocity of ozone, were evaluated by test simulations using actual emission and meteorological data on an industriai area facing an inland sea.
A synthetic simulation with the optimum values for the examined parameters have given a diurnal variation of ozone concentration which coincides fairly well with the observed pattern.

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Inhibitory effects of trace metal ions (Mn²⁺ and Fe³⁺) on the intensity of chemilumines-cence accompanied by oxidation of luminol with hydrogen peroxide in the presence of Fe (CN) ₆^3-catalyst were compared with those for a luminol-H₂O₂-Cu²⁺ system. The chemiluminescent intensity for the Fe (CN) ₆^3- system was smaller twentieth than that for the Cu²⁺ system. However, the decrease in the intensity due to the metal ions found for the Fe (CN) ₆^3- system was below 10 % of that for the metal ion free solutions in the metal ion concentration range up to 1×10^-6 mole 1^-1 and above 10^-5 mole 1^-1 the decrease in the intensity seemed to be very smaller than that for the Cu²⁺ system. This luminol-Fe (CN) ₆^3- system may be favorable to determination of H2O2 in clouds and rainwater containing relatively large amount of metal ions.

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During the period from Jun., 1983 to May, 1984, dustfall samples with rain water were collected by deposit gauge method at 14 sampling sites in Nara Prefecture and the amount of depositsof ten dissolved components (H⁺, SO₄^2-, NO₃^-, Cl^-, F^-, Na⁺, K⁺, Ca²⁺, Mg²⁺, NH⁴⁺) were measured. And the principal component analysis [PCA] were carried out with respect to these amount of deposits.
As to the pH of samples and the amount of deposits of dissolved components distinguished by population density, the pH was liable to decrease with increasing the population density and the amount of deposits of SO₄^2-, NO^3- and NH₄⁺ regarded to be the pollutants originated from human work was liable to increase with increasing the population density. On the other hand, the amount of deposits of Na⁺, K⁺, Ca²⁺, Mg²⁺, NH⁴⁺ and Cl regarded to be the pollutants originated from natural generation was almost constant to variation of population density.
As a result of PCA, the amount of deposits of dissolved components was able to characterized with two principal components (z₁, z₂). The first principal component z₁ was considered to be a factor indicating the degree of synthetic amount of deposits and the second principal component z₂ was a factor indicating the contribution of origins of dissolved components. The degree of synthetic amount of deposits and the contribution of origins of dissolved components of monthly and locational distinction was possible to evaluate by the use of these two principal components of z₁ and z₂.

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