Restoration of Water Environment by Covering Granulated Coal Ash in Brakish-water Lake Nakaumi, Japan

Abstract

Granulated coal ash was used to restore water environment in a brackish-water lake, Nakaumi, Japan, whose sediment was heavily deteriorated with organic substances. Number of bivalves, Tapes japonica and Scapharca subcrenata, which were important fisheries resources, were significantly recovered 2-3 years after the granulated coal ash covering. Oxydation-reduction potential of the amended sediment with the coal ash was significantly high compared to those with natural sand. Dissolved oxygen concentration in the overlying water was also high at the coal ash amendment site. This means, the sediment oxygen consumption was depressed by covering with the granulated coal ash. From these results, granulated coal ash can be effective to restore water environment and bivalve habitat by amending the organically-enriched sediments.