Experimental Restoration of Fishing Ground of Brackish-water Clam in a Cold Region Using Fluvic Acid Iron Silica Material

Various materials have been developed to restore sludge-accumulated bivalve fishing grounds. In this study, we examined the effectiveness of using an improved material, fluvic acid iron silica material （ FS material ） , to treat deteriorated sediment by the photo-Fenton reaction of Fe-humic substance complexation in Lake Shibunotsunai, northern Japan. From the results of a field experiment with FS material laid on the lake bottom, the thickness of deposited mud, mud content, and ignition loss of bottom sediment were partially reduced in the FS material site compared with the control site, but the effect was much smaller than in the previous research. Laboratory experiments revealed that the effectiveness of FS material was enhanced by a high water temperature and by using a greater amount of FS material. It has been found that if there is a current in the FS material site, the decomposed sediment surface layer may peel away. As a result, it is important to consider the applicable utilization method of FS material in accordance with the locality.