Organometallic compounds are broadly used despite of the fact that some of them have brought several severe environmental pollutions due to their strong toxicity. We have constructed a prototype of a database of organometallic compounds concerning to environmental science, mainly compounds on the market, which have a great possibility to pollute environment. The database contains graphical data of molecular structures, in addition to fundamental properties, safety, toxicity and industrial informations. This database is intermediate between public databases and in-house ones and may be supplied to the ones who are concerned with environmental pollution.

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Four transformation methods from the Braun-Blanquet cover-abundance scale to percentage cover were examined for the calculation of diversity index (H') and evenness index (J'). Percentage cover data of species were collected in fifty stands of various herbaceous plant communities. A newly proposed transformation method, based on the arrangement of cover values in accordance with the geometric progression in each cover-abundance class, is most effective for the estimation of H' and J'. Transformation to geometric mean of class limits is useful for calculation in both diversity and similarity indices. Transformation methods to mean cover (arithmetic mean of class limits) and the arrangement in accordance with the arithmetic progression in each class perform poorly in calculation of H' and J' because of over estimation of cover values in low cover-abundance classes. The difference of performance among the transformation methods seemed to be caused by the geometric nature of the community structure of the stands. Transformation methods are recommended to be selected in connection with the community structure of the subject stands.

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The spreads of urban districts have been eroding many kinds of land uses in and around the cities. For the conservation of open space, it is important to know the expanding directions of urban districts, which are mainly caused by the concentration of population. The purpose of this study is to clarify the change of land uses in proportion to the spread of "Densely Inhabited District (DID) ", for making a guideline of conserving open space. The distribution patterns of DID within a 50 km radius of Tokyo Metropolitan Area were compared during the period from 1960 to 1975. Over 70% of the newly spread DID areas appeared in the areas adjacent to the existing DID. There is a close interrelationship between the spread of DID and that of urban district in the northeastern area of Kanto district. On the basis of the distribution of open space in and around DID in Saitama prefecture, the author proposed four "Conservation Zones" of open space-central DID zone, marginal DID zone, fringe zone and remote zone. The conservation guideline of open space is discussed for each of four zones. (*DID is defined as an area within a local body that is composed of a group of contiguous enumeration districts, each of which has a population density of about 4, 000 or more inhabitants per square kilometer, and whose total population exceeds 5, 000 at the date of survey.)

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The behavior of heavy metals in influent was studied at three wastewater treatment plants and three community wastewater treatment plants that treated domestic wastewater and little industrial wastewater or only domestic wastewater. Heavy metals concentration ratio of activated sludge was evaluated at 103 to 105 for zinc, cadmium, copper, chromium, lead, nickel, iron and manganese in settled sewage. The concentration ratio of activated sludge maximized at 13 days sludge age for zinc, copper, chromium, lead, nickel and iron. In a laboratory simulation of the batch activated sludge process, activated sludge was allowed to equilibrate to four sludge age between 5 to 20 days with regular addition of zinc to the aeration tank. The highest zinc concentration in activated sludge occurred at 15 days sludge age. It is possible to maintain a low concentration of zinc in activated sludge by watching industrial wastewater closely. It is possible to control to a low concentration of zinc in composted sewage sludge, which is made from excess activated sludge, by keeping sludge age short.

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[in Japanese]

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