WATER QUALITY RESTORATION IN LAKES AND RESERVOIRS USING NATURAL ENERGY

通常在富营养化湖泊和水库中观察到的溶解氧（DO）耗竭会损害天然底栖生物并促进沉积物中的营养物质释放。为了解决这些问题，提出了一种将含有大量DO的地表水注入经常耗尽DO的底层的方法。本研究在面积为100m^2的围护系统和面积为15000m^2、最大深度为5m的水库中，通过实地试验研究了连续或间歇向低磷离子注入地表水对水质恢复的影响。此外，还通过室内试验研究了该系统对泥沙质量恢复的作用。田间试验结果表明，该系统抑制了沉积物中养分和溶解金属的释放，即使在DO被沉积物需氧量（SOD）耗尽的情况下。实验室实验结果也显示，手术后测量的SOD值比手术前测量的值要小。这可能是由于2000年夏季地表水的持续注入促进了沉积物中有机物质的持续DO消耗。实验和观测结果表明，该系统是恢复封闭水域水沙质量的有效方法。

Dissolved oxygen (DO) depletion, which is usually observed in eutrophic lakes and reservoirs, damages natural benthic organisms and enhances nutrient release from the sediment. As a countermeasure aganist these problems, a method which injects surface water including a large amount of DO into the bottom layer, in which DO is often depleted, was proposed. In this study, the water quality restoration in case of continuous or intermittently injection of surface water into hypolimnion was investigated by field experiments performed in an enclosure system which is 100m^2 in area, and in a reservoir which is 15000m^2 in area and 5m in maximum depth. Furthermore, the effect of this system on sediment quality restoration was also investigated by a laboratory experiment.Field experimental results revealed that this system suppressed nutrient and dissolved metals release from the sediment even when DO was depleted by sediment oxygen demand (SOD). Laboratory experimental results also revealed that SOD measured after the procedure had smaller values than those measured before the procedure. This might be due to the continuous DO consumption of organinc materials in the sediment during summer in 2000, promoted by continuous injection of surface water. The experimental and observational results indicate that this system is a promising method to restore water and sediment qualities in enclosed water areas.