Studies on the Function of Wetland and Shallow Aquatic Ecosystems for Environmental Conservation

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From 2 years' study to estimate the function of wetland and shallow water ecosystem for environmental conservation, the following results were obtained.(1) In order to estimate the effect of rainfall on a shallow aquatic ecosystem in the urban area, rain samples were collected and analyzed at Nagoya University during 1995, and the data were compared with those of Nagoya city during recent 10 years. The result showed recent trend in decreasing sulfur and increasing nitrogen compound in the rain component, which indicated that rain might be eutrophication agent on the oligotrophic ecosystem.(2) In order to elucidate the characteristics of shallow aquatic ecosystem in the sulfur and nitrogen cycling, filed studies concerning on the sulfur and nitrogen budget, microbial activities on the degradation of organic matter, and the denitrifying bacterial flora were carried out at a small pond and its surrounding wetland area in Nagoya city suburb. The result showed that wetland had large bufferi … More ng function against higher concentration of sulfate inflow and nitrogen supply through precipitation.(3) In order to estimate the effect of nutrient supply through precipitation on oligotrophic wetland, field studies on the nitrogen cycling microbial flora were carried out in parallel with flux measurement of methane, nitrous oxide and hydrogen at Kushiro wetland. The result showed that sulfur supply through precipitation was crucial for ombrotrophic bog, where sulfate was completely depleted in summer. As for the nitrogen component, the fact that free-living nitrogen fixing bacteria appeared abundant in bog (high moor) but not detected in fen (low moor) indicated the nutrient level of nitrogen in the environment.(4) The shallow aquatic ecosystem plays an important mitigating role for nutrient loading on the lower watershed agaist eventual inflow or loading of nutrients by precipitation. Wetland or shallow aquatic system should be managed properly for the total environmental conservation. Less