Branching system and mechanical characteristics (load and strain energy until fracture) of trees were investigated using five species, Masaki (Euonymus japonicus), Tobera (Pittosporum tobira), Enoki (Celtis sinensis var, japonica), Mochinoki (Ilex integra), Hisakaki (Eurya japonica), growing at the southernmost part of Miura peninsula in Kanagawa Prefecture, Japan. Strahler's method of expressing river form was applied to define branching order of a tree. Based on limit fracture load (P₁) and limit strain energy until fracture (U₁) of each branch order, total limit fracture load P_t (sum of P₁ of same order branches)and total limit strain energy U_t (sum of U₁ of same order branches) were calculated for each branch order. Values of P₁ and U₁ were increased exponentially with an increase of branch order. However, P_t and U_t values were shown to be independent of branch order, but dependent on tree species and habitat conditions such as exposure to wind. It is concluded from the results of this study and field survey of coastal vegetation in Miura peninsula that Mochinoki and Hisakaki are tolerant of wind action and able to form tree community in wind-exposed habitat in this area.

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When precipitation passes through forest canopies, some ion concentration may increase while others may decrease in the throughfall. The enrichment phenomena result from the ion leaching from plant tissue and the removal of dry deposition, while decrease in ion concentration is due to ion absorption in-to plant tissue. This study was carried out to make clear how chemistry of the simulated rain water solution was changed when epiphytic lichens and tree leaves were submerged at varing acidity and time. The obtained result was as follows; (1) Lichens leached K⁺(27.2±3.4μeq/g), Mg²⁺(7.1±1.01μeq/g) and Ca²⁺(18.4±5.0μeq/g) to the solution, absorbed NH⁴⁺(6.3±2.6μeq/g) and NO³(3.0±0.3μeq/g) from the solution. (2) Leaching of Ca²⁺ and Mg²⁺ from the thallus increaed significantly with increasing H⁺concentration of solution, while K+ was not so. (3) Absorption of NO3^- to the thallus increased with increasing H⁺ concentration of simulated rain water, while that of NH4⁺ decreased in reverse. (4) The linear relationship between leaching and absorption through plant tissue and time was observed with respect to K⁺, Mg²⁺, Ca²⁺, NH4⁺ and NO3^-, respectively. Though leaves of Cryptomeria japonica and Quercus serrata responded in manners similar to those of the lichens, the leaching amounts were about 1/2-1/9 those of the lichens, except for Quercus serrata which indicated the possibility of the leakage of K⁺ due to damage of cuticle tissue.

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When adverse effects of hazardous chemicals on human health can be measured quantitatively as the number of deaths in a population due to the exposure to the chemicals for a certain period, economic benefits from regulating such chemicals can be obtained as the product of the number of deaths and economic value of a life. The consensus in cost-benefit analysis is that economic value of a life must be measured as value of a "statistical" life, that is, the average value of people's ex ante willingness to pay for reducing probability of death divided by the amount of the reduction of the probability. In this paper, values of a statistical life of Japanese people are obtained from a contingent valuation survey on willingness to pay for reducing the cancer risk in drinking water. The bidding game method and the take-it-or-leave-it approach were adopted in the survey. The obtained value from the bidding game method is 2.24 billion yen and the values from the take-it-or-leave-it approach range from 2 .53 to 3.55 billion yen. The results are discussed from the viewpoints of the choice of appropriate measure of WTP-mean or median-, the comparison of the results from the bidding game method and the take-it-or-leave-it approach, the comparison of the results with the estimates in the U. S. and the U. K. studies, and the effects of the characteristics of risk.

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The measurements of five chlorocarbons (CC), chloroform (CF), carbon tetrachloride (CT), 1, 1, 1-trichloroethane (1, 1, 1-T), trichloroethylene (TR) and tetrachloroethylene (TT) in atmospheric environment have been carriede out at the five sites of Osaka City between September in 1989 and November in 1992 (seven seasons). The results may suggest as follows: (1) only small differences were observed among the average concentrations of these CC at the five sites in the narrow area such as Osaka City, (2) the relatively large changes were detected in the seasonal average concentrations of three CC except CF and CT, (3) the emission sources of these CC may be classified roughly into two categories of wastewater (water area) and other vaporation sources. The average ratio (21.5) of [1, 1, 1-T+TR+TT] / [CF] in the ambient air was much higher than that (6.72) published in the wastewater. On the assumption that all of ambient CF is caused by wastewater, the contribution of this source could be calculated to be 31.3 % from the both ratios, which may be the maximium contribution to the ambient 1, 1, 1-T, TR and TT.

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A method using Index of Atmospheric Purity (TAP), proposed by LeBlanc and DeSloover, is one of the phytosociological method based on the distributions of epiphytic bryophytes and/or lichens to evaluate the atmospheric purity. In the present paper, a new method using Evaluation Index of Air Quality (EIAQ) which seemed useful as well as TAP method was investigated. EIAQ values were calculated from the sensitivity of species for air pollution based on the literature and the author's observation, and the degree of species number and coverage on the basis of the data of epiphytic bryophyte vegetation at 248 sites in Hyogo Prefecture. EIAQ values were divided into five evaluation zones including epiphyte desert. Their zones of 0, I, II, III and IV are highly disturbed zone (epiphyte desert), disturbed zone, lightly disturbed zone, quasi-normal zone and normal zone, respectively. The new proposed method was applied to mapping of environmental aspect in Hyogo Prefecture. And it was considered that EIAQ method was useful one for evaluation of environmental condition from the result that EIAQ values decreased around urban and industrialized regions and the relation between changes in EIAQ values and changes in concentration of some air pollutants during about 10 years in the Higashi-Harima region.

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The seasonal variation of ozone in the lower troposphere at Sapporo is different from that in the riliddle troposphere. In order to understand this difference, isentropic trajectories are computed for the lower and the middle troposphere over Sapporo. Except in summer, downward transport from the middle troposphere to the lower troposphere often occurs. Mean synoptic vertical velocity for spring, summer, autumn and winter are 38.2, 6.4, 59.4 and 52.9 hPa/day, respectively. On the other hand, trajectories of air parcel show no clear seasonal variation in the middle troposphere. From the results, we conclude that the seasonal variation of lower tropospheric ozone at Sapporo is controlled by ozone concentration in the middle troposphere and magnitude of synoptic scale downward transport. In the middle troposphere, the seasonal variation of ozone has little relation to synoptic scale vertical motion. It may be controlled by in-situ photochemistry in the troposphere and/or transport other than synoptic scale motion.

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