Author(s): Koji Asai; Tetsuo Ohwaki; Takumi Odamura; Ei-ichi Hoshiyama; Hajime Shirozu
Linked Author(s): Koji Asai
Keywords: High DO concentration water; Shimaji-gawa River Reservoir; Arsenic; Iron; Manganese
Abstract: Shimaji-gawa River dam reservoir is in Shunan City, Yamaguchi Prefecture, Japan. This reservoir had also suffered from the elution of heavy metals with anaerobic states. To prevent the water quality in this reservoir from pollutions, a device to supply high DO concentration water into the bottom layer has worked in Shimaji-gawa River dam reservoir since April 2010. This device didn't work from February to July in 2013 because of mechanical trouble of this device. The monitoring of the water quality at the fixed observation point has conducted by Yamaguchi Office of River and Road from 2006 to present. We have investigated the effect of the supply of the high DO concentration water of the improvement of the water quality and the long-term behavior of the heavy metals using the long-term period monitoring data and the longitudinal observation data conducted recently. It is found that DO have spread over the region where the water quality must be improved. The concentrations of Arsenic and Iron decreased greatly in a few months. On the contrary, it took almost 1 year for Manganese to completely decrease, and manganese started to re-liquate out when the device stopped. Moreover, the concentration of Manganese didn't decrease satisfactory.
Year: 2018