Ozone is the main photochemical oxidant that causes leaf damage in many plant species, thereby decreasing the productivity of crops and forests. Ozone produces reactive oxygen species suchas superoxide radicals and hydrogen peroxide, which induce phytohormones such as ethylene, salicylic acid and jasmonic acid. Phytohormones are required for plant growth, development and defense response. It is also known that phytohormones regulate the extent of leaf injury in ozone-fumigated plants. In recent years, responses to ozone have been studied using genetic-modified plants and mutants, which have aitered the hormone levels and signaling. From this researches, the role of phytohormones and the complexity of their signaling is being clarified. The present focused on the biosynthesis of phytohormones and their cross-talking effects in ozone-exposed plants.

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Thus far, many wind tunnel experiments have been conducted in order to study the characteristics of atmospheric dispersion inside obstacles wakes in cases of accidental release of hazardous gas from industrial facilities. However, this paper considers the problem by focusing on the situation of the release point of thehazardous gas. In this study, we assume the pollution source to be located at a distance from various types of obstacles. Wind tunnel experiments were conducted to investigate the characteristics of mean and fluctuating concentrations around a normal plate. A tracer gas was emitted from a source located at a distance of twice the plate height upstream from the plate. The characteristics of plume entrainment into the wake region of the plate were clarified by examining its relation with flow patterns and turbulence structures. In addition, we focused on the characteristics of various kinds of peak-to-r. m. s. concentrations defined as values which were not exceeded for 90, 95, 99% of the cumulative probability density function of the concentration fluctuation. Based on the results, it was found that the concentration ratio at maximum 10% values could be estimated by the exponential probability distribution functions of the concentration fluctuation, independently of the concentration fluctuation intensity.

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We developed an estimation model for the environmental impact of automobiles that has high resolution in terms of time and space. The scheme of the model framing is shown below.
(1) As a unit of running, the pair of the idling section, showing time transfer, and the running section (from start to stop), showing spatial transfer, was defined as a trip segment.
(2) In each mode (idling, acceleration, cruising, and deceleration) of a trip segment unit, running characteristic values (velocity, acceleration, etc.) and the amount of environmental impact (EI) was calculated. Regression analysis was applied to these values and EI was expressed with the following formula for each vehicle.
El=C×f (running characteristic values) C: paramcter speculiar to vehicles
(3) The parameters C were generalized with the item value of the vehicles, and a general-purpose model that estimates EI from vehicle speed data was created.
EI=α(item value of vehicles)β×f (unning characteristic values)
α, β: regression coefficient
item value of vehicles: weight of vehicle, displacement
The defining feature of this model is its ability to estimate the amount of environmental impact from an automobile by an indirect technique using the running records of a digital tachometer, etc., without using a chassis dynamometer. Because the estimation method is based on running characteristics such as acceleration, the model can clearly reflect the difference in each driver's operating method.
This paper showed the scheme of the model framing for heavy-duty diesel vehicles that meets the current Japanese short-term and long-term standards for emissions, and the model was verified by observation.

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Atmospheric hydrogen peroxide (HOOH) and organic peroxides (ROOHs) were measured during the period of August 23-26, 1998 at Shimosha (ca. 700 m a. s. l), located on the southern slope of Mt. Oyama (35°26' N, 139°14' E, 1252 m a. s. l.), Kanagawa Prefecture, Japan in order to evaluate the possible effect of these peroxides on the decline of Japanese fir (Abies firma Siebold et Zuccarini) forests on the mountain. Peroxides were measured by fluorometry after an enzymatic separation of these peroxides, which followed the collection of the atmospheric peroxides by the stripping coil method. The concentrations of ozone (O₃), nitrogen oxides, and meteorological factors were also measured during the study period. HOOH concentrations ranged from 0.8 to 4.0 ppbv with the highest reading in the daytime and the lowest in the night-time. O₃ concentrations that ranged from 3.1 to 70 ppbv showed a similar temporal variation as that of HOOH; thus, there is a strong correlation between these two photooxidants. ROOHs concentrations were in the range of 0.6-2.2 ppbv and showed a reverse diurnal variation to the HOOH. These results imply that HOOH is photochemically produced during daytime, as is O₃, whilst ROOHs are generated by various reactions, such as the reactions of O₃ with non-methane hydrocarbons (NMHC), in both the day-and night-time. As these peroxides occur with relatively higher concentrations on the mountain, the peroxides may have harmful effects on the fir trees.

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