Large input of wet and dry acidic deposition including acid rain, fog, sulfur oxides and nitrogen oxides will cause soil acidification. Acidified soil will release large amount of soluble aluminum toxic to plant root growth at low pH zone. As high amount of cations may alleviate Al toxicity or low cations may aggravate its toxicity, this report describes that whether concentration of Ca will affect the incidence of Al toxicity in Cryptomeria japonica and Chamaecyparis obtusa grown in nutrient solution culture or not.
Three concentration levels of Ca: 0.4, 0.8, and 1.6 mM in the Hoagland's No.2 nutrient solution at pH 3.5 to 4.0 was combined with four levels of Al: 0, 1, 2, and 5 mM of aluminium chloride. Solution culture experiment was conducted for 14 weeks.
Both Cryptomeria japonica and Chamaecyparis obtusa did not have significant growth reduction at and below 2 mM of Al. However, 5 mM of Al significantly reduced plant growth. Concentration of Ca in the range from 0.4 to 1.6 mM did not have significant influence on Al toxicity.
Sigmoidal fitting curve from several Al toxicity experiments including the current experiment in the Japanese conifer species: Cryptomeria japonica, Chamaecyparis obtusa and Chamaecyparis pisifera, suggested that Al concentration potentially toxic to Japanese coniferous trees was 2 mM and higher, critical point for growth reduction was below 1 for Ca/Al molar ratio in the nutrient solution and below 5 for (K+Ca+Mg)/ Al. Value for 20% growth reduction was 0.25 of Ca/Al or 1.0 of (K+Ca+Mg)/Al. However, it had a wide range depending on the experimental conditions.

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In order to monitor highly time-resolved and wide-ranged behavior of Elemental Carbon (EC), a thermal analysis method has been developed to determine EC content in aerosols collected on the filter-tape mounted in automated aerosol (less than 10μm in diameter: refereed to as Suspended Particulate Matter, SPM), monitors. The monitor, utilizing β-ray absorption of collected SPM on glass-fiber filter reinforced with acrylic resin binder, is widely used in ambient air quality monitoring stations in apan. For subsequent EC analysis, punched-out sports of filter loaded with particles were thermally treated to remove acrylic resin and organic aerosols simultaneously. The optimal condition determined was instantaneous pyrolysis in Helium atmosphere at 640°C for five minutes. Determined EC concentration by the method showed good correlation with that from SPM samples collected on quartz-filter but was systematically less than that. An extensive measurement of EC over the Kanto Plain, Japan has been conducted by using filter-tape samples in SPM monitors collected from 37 monitoring stations, and quartz-fiber samples collected at five sites during intensive field study period. This revealed the two dimensional distribution of EC showing the formation and dissipation of high concentration area (maximum concentration of 130μg Cm^-3) having 50 km in diameter.

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Plume-models evaluating environmental maximum surface concentration far from site-boundary under the releasing condition of 120 m high above ground level and non-buoyant gas are studied to be applied to the fumigation due to thermal internal boundary layer in the coastal area. The data of atmospheric diffusion experiments, TOKAI 82-83 by Japan Atomic Energy Institute in the coastal area including Tokai-village and its neighborhood, Ibaraki-prefecture, east coast of northen part of Kanto region, Japan, August of 1982 and 1983 are analyzed in this study.
Meteorological conditions of fumigation are not decided strictly in the present circumstances as the three dimensional automatic observational methods of atmospheric turbulence and concentration are not developed sufficiently. For that reason, the cases when the evaluations by the current method are clearly understimated under the meteorological conditions of daytime of August, comparatively fine weather, wind from sea, thermal internal boundary layer and the stable atmosphere near the outlet of air-tracer are considered to be the fumigation in this study.
The current method above-mentioned in this study means the method evaluating environmental maximum surface concentraion far from site boundary by Gaussian-plume-model with Pasquill-stabilities and PGdispersion-parameters.
As a result of data-analysis, it is found that vertical gradient of temperature near the outlet of air-tracer is bigger than-0.5°C/100 m and therefor not always inversion layer of air-temperature in the case of fumigation.
The current method and the atmospheric dispersion model under fumigation conditions for potential accident consequence assessments at nuclear power plants in Regulatory Guide (RG) 1.145 of U. S. Nuclear Regulatory Commission (US. NRC) are examined by the observations.
According to the examinations, they are found; 10 the current method tend to underestimate, (2) the improvement of the current method is a little even if the parameters of the current method are shifted, (3) the concentration calculated by the fumigation-equation in RG 1.145 is close to upper limit of observations at each distance and is not smaller than any observation at each distance.
Therefore it is clear that the fumigation-model of US. NRC is one of the models proposed for the short period high concentration evaluation under the condition of fumigation caused by thermal internal boundary layer in Japan.

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The concentrations of eight volatile organic chlorinated chmicals in indoor air, outdoor air and personal exposure concentrations in five married couples living in Osaka were determined in October and February, each twice (1995 and 1996), in order to know the pollution levels of the chemicals in residential air and to estimate the absorption amounts of them in personal exposure lebvels.
The chmicals in atmosphere were collected by passive gas sampling tubes containing charcoal, and were determined by using gas chromatograph with electron capture detector. The geometric mean of. indoor concentration of p-dichlorobenzene (3.1 ppb, v/v) was highest, followed by those of 1, 1, 1-trichloroethane (0.52 ppb), trichloroethylene (0.47 ppb), chloroform (0.39 ppb), tetrachloroethylene (0.28 ppb), carbon tetrachloride (0.093 ppb), bromodichloromethane (0.052 ppb) and chlorodibromomethane (0.024 ppb). As indoor concentrations of p-dichlorobenzene and trihalomethanes were higher than outdoor concentrations of them in all houses, major sources of these chemicals were considered to be present in indoor. Further, the sources of the trihalomethanes were presumed to be same on the basis of the results of the correlation analysis among the concentrations of eight chemicals. The personal exposure concentrations of p-dichlorobenzene (1.5-21.2 ppb) were highest of those of the chemicals in husbands and wives in all homes.
The absorption amounts of each chemical in personal exposure levels were estimated from the results of the previous pharmacokinetic studies of the chemicals in rats. p-Dichlorobenzene (2456nmol/day/60 kg of human body weight) was absorbed most abundantly amoung the volatile organic clorinated chemicals, comprising about 70% of the total absorption amounts of eight chemicals. The amounts of trichloroethylene (84 nmol) and chloroform (224nmol) were much next to that of p-dichlorobenzene, but the absorption amounts of the other five chemicals were much less than those of p-dichlorobenzene, trichloroethylene and chloroform. p-Dichlorobenzene, which was possibly carcinogenic to humans and was absorbed abundantly, was considered to be one of thee most noteworthy chemicals as indoor contaminant inhaled chronically.

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Differences of atmospheric environment between weekday and weekend (saturday and holiday) in Tokyo were surveyed about NO_x, NO₂, SO₂, SPM, CO, NMHC, temparature and wind speed from measured data. We got some important knowledge about weekly cycle of atmospheric environment as follows.
(1) Concentrations except OR and temparature fall in holidays.(2) 98 percentile concentration of daily mean NO₂ fall remarkably in holidays so that numbers of monitoring points exceeding environmental criteria could decrease to 1/3 of the real world exceeding points.(3) Ratio of NO₂/NO_x decreases in holidays, and it's effect for NO₂ concentration may be important also. It was presumed that the decrease of primary NO₂ emission from diesel trucks in holidays is one of the causes of falling NO₂/NO_x.(4) 98 percentile concentrations of daily maximum OR decrease at rural area but increase at urban area.
And some research themes in the future using the informations of weekly cycle about atmospheric environment are depicted.

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