Considering Environmental Standards Based on Soils and Water Quality in the Biotopes around Urban Areas in Japan

抄録

Biotope, where the ecosystems have been lost due to industrial development and urbanization, should be restored to rehabilitate the organisms of the original inhabitants. Although there are more than 1,500 school biotopes in Japan, few research have been conducted for evaluating their soil and water quality. Compared to lakes and rivers, biotopes have problems as there is less data on soil and water quality. Furthermore, there were no ‘environmental standards for biotopes,’ so it was hard to evaluate if their soil and water conditions are appropriate for biotopes. Accordingly, the aims of this study are to determine soil and water quality in several biotopes and to develop a draft of environmental standards for biotopes. Various surveys were conducted by disseminating questionnaires to elementary school students on current management systems and their perception of the function of biotopes. Also, soil and water samples were collected from a public park and four elementary schools in Tokyo and Kanagawa Prefectures for quality analysis. As biological characteristics, coliforms and E. coli were measured from soil samples. Also, total nitrogen (TN), total phosphorus (TP), pH, EC, SS, coliforms and E. coli were measured from water samples. The results of TN and TP tended to increase in summer due to the increase in algae. The school that keeps bantams and goats near the biotope detected coliforms and E. coli. The excrement of these animals may cause contamination. However, the results from the questionnaire survey indicated that the water appears to be clean. Accordingly, there was a difference in their perception and water quality condition. Therefore, the draft of environmental standards, TN and TP values may be consistent with the standards for the lakes, although there are size differences between lakes and biotopes. However, the standards on coliforms and E. coli should be more restricted, since children often play with biotopes.