Experiments were conducted to investigate reductive decomposition of volatile organohalogen compounds on activated carbon in an inert atomosphere. CFC-113 (CCl₂FCCLF₂) vapor (1000-6000ppm) was decomposed at 300°C, but by-products were not detected at 600°C. Water vapor acts as a hydrogen source to decompose CFC-113. The main by-product was CClF=CF₂, resulted from elmination of chlorine atoms from CCl₂FCClF₂. In addition, CCl₂F₂, CClF₃, CHF=CF₂ and C₂HClF₄ were detected by the GC/MS analysis. The catalytic reductive decomposition on actvated carbon was also effective in decomposing vapor phase CCl₄ and CCl₂=CCl₂.

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A simple and highly sensitive analytical method for 9 volatile organohalogen compounds (VOHC) indoors and outdoors was developed. This method consists of collection of VOHC by a passive sampler, extraction of VOHC into toluene by mechanical shaking, and automatic separation analysis by a capillary gaschromatography using electron capture detector (GC/ECD).
The passive sampler developed is a porous polytetrafluoroethylene (PTFE) tube [30.3±0.37 mm in net collection length, 5.0 mm in inner diameter, weight 0.990 g] uniformly packed with activated charcoal (194.4±3.8 mg). Precision of VOHC collection by this sampler was high. Coefficient of variation of VOHC amount collected by the sampler was in the range of 3.1-8.4%.
GC/ECD was highly sensitive and shown repeatability. The determination limit was ranged from 1.4 to 99 pg for the 9 VOHC (S/N=10).
An equation was derived for conversion of VOHC amount collected by passive sampler to VOHC concentration in air on the basis of the results of simultaneous measurement by passive and active sampler indoors and outdoors. The equation derived resembled with Freuntlich's adsorption isotherms and covered wide range of air concentration.
Recovery from spiked samplers were ranged from 88.3-106.3% except o-dichlorobenzene (80.1%). This sampler could be stored at least one week under ambient conditions by packing in aluminum package.
This method was applied to a preliminary field study, and it was found that 7 VOHC (dichloromethane, chloroform, 1, 1, 1-trichloroethane, carbon tetrachloride, trichloroethylene, tetrachloroethylene, p-dichlorobenzene) were detected from indoor and outdoor air as well as personal sample.

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Three-year old cutting plants of Cryptomeria japonica, Chamaecyparis obtusa, and Chamaecyparis pisifera grown in andosol were exposed to simulated acid rain (SAR) for 23 months. Soil samples and root growth were analyzed. The pHs of SARs containing sulfuric, nitric and chloric acids were adjusted to 4.0, 3.0 or 2.0. Deionized water of pH 5.6 was used as the control. Total precipitation of SAR for 23 months were 2460, 3960 or 5450 mm. Soils were fertilized with or without 80-80-80 kg/ha/year of N-P₂O₅-K₂O of a commercialized fertilizer.
Soil pHs exposed to SAR of pH 4.0 did not show any significant differences from those of soils exposed to pH 5.6. Exposure to SAR of pH 2.0 for 23 months lowered soil pH to 4.0 from 4.8 of the initial value. The pH of fertilized soil was lower than that of non-fertilized one. Total precipitation and cultivated plant species did not significantly affect soil pHs.
Exposure to 5450 mm of pH 2.0 for 23 months significantly decreased concentrations of water-and 1M ammonium acetate-soluble Ca and Mg in soils, while Al concentration increased. Thus, molar ratio of (K+Ca+Mg)/Al reduced significantly by the exposure to SAR of pH 2.0. Plant roots were exposed to Al toxic conditions for a year by the exposure to SAR of pH 2.0, but this ratio did not change from about 0.4.
Japanese conifer species did not show any significant reduction in root dry weights of plants grown without fertilizer and with exposure to pH 2.0, even if the molar ratio of (K+Ca+Mg)/Al significantly lowered by the increasing of Al concentration and the decreasing of Ca and Mg concentrations associated with lowering soil pH.
Therefore soil acidification stress associated with the exposure to SAR did not appear to cause significant growth reduction in Japanese conifers.

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The methods of sampling, carrying and keeping, and the instruments for the measurement of atmospheric peroxyacyl nitrates (PANs), such as peroxyacetyl nitrate (PAN) and peroxypropionyl nitrate (PPN), were developed for field studies at remote sites and by aircraft. PANs in the air were collected by the U-shape Teflon trap [tube (30 cm L, 2 mm I.D.) packed with ca. 0.2g Teflon beads] chilled with dryice-ethanol or pulverized-dryice. The sampling duration was 10 to 120 minutes, depending on the sampling volume (100 to 1000 ml) and the purposes.
Two kinds of collecting techniques were developed for the sampling of PANs in remote sites. One was composed with the U-shape trap attached to a Teflon four-way valve and a 200 ml glass syringe mounted vertically. This is adequate to th temporary sampling without any electric power sources. Another was a completely automated instrument for continuous sampling throughout a day. This is composed of 10 sampling lines connected to the U-shape traps which are changed in cycles with electric solenoid valves.
A reliable sampling instrument was developed for the survey by aircraft. This is composed of the trap attached to the valve, a mass flow control system, two suction tanks (volume; 1l), an evacuation pump, electric recorder for monitoring of the sampling flow rate and the temperature and pressure of the tanks, and the timers for purging and sampling time.
The decay rate of PANs in the chilled sampling traps was below 1.5%/day, and the sublimation rate of dryice is ca. 70g/hour in the plastic box of thick walls. The keeping technique of PANs samples in the traps chilled by pulverized-dryice enabled us to carry them from remote sites to the central laboratory by aircraft or by commercial dilivery systems without any virtual decay of PANs. PANs were analyzed by GC with ECD-(PANs Absorbent)-ECD at the laboratory. The detection limit of PANs was ca. 2 ppt (v/v) for 500m/ sample.
The developed methods were used for the field studies at four remote islands and by an aircraft since 1991. PAN and PPN were detected in most of over 500 samples. Mean concentrations of PAN and PPN in the island and in lower troposhere over Yellow Sea to Japan Sea were 0.1-0.4 ppb (v/v) and 0.01-0.03 ppb, respectively. Good correlation between PAN and PPN at the each point was observed, and PPN was found to be 5-9% of PAN.

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Classification of atmospheric stability by vertical turbulence intensities (σ_w/U) was investigated for the estimation of air pollution concentration over sea surface.The atmospheric stability categories are Pasquill-Gifford (P-G) Stability Categories and correspondedto the vertical dispersion coefficient σz on Pasquill-Gifford's chart (PG chart) or Turner's chart (PGT chart).
Main methods in this research were (1) application of similarity theory of surface boundary layer, (2) application of US-NRC's classification of atmospheric stability by σ_A and ratios σ_y to σ_z at 100 m distance on PGT chart, (3) application of US-EPA's classification of atmospheric stability by σ_E.
The results of above-mentioned three methods were similar to each other. Mean of these results are presented in the following table. This table is applicable to atmospheric stability classification over not only the flat smooth ground surface but also sea surface within about 1 km away from source of air pollution.
σ_W: Standard deviation of vertical wind speed fluctuation. U: Mean horizontal wind speed. US-NRC: U. S. Nuclear Regulatory Commission.σ_A: Standard deviation of horizontal wind direction fluctuation. USEPA: U. S. Environmental Protection Agency.σ_E: Standard deviation of vertical wind direction fluctuation.

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