Abstract
The objective of this study is to clarify the environmental conditions and evaluate the effect of the restoration of a shallow area constructed of steelmaking slag (filling layer) and dredged sediments of the estuary (covering layer) . We monitored the pH and the turbidity of the bottom layer during construction, and then the pH of porewater (both layers) and the overlying water after the completion of construction. Moreover, benthic faunal surveys were carried out 2 or 3 years after the completion. The pH of seawater remained at a normal level despite increased turbidity at slag disposal sites during construction. After the completion of construction, the pH of the filling layer pore water was often high. However, the covering layer and overlying seawater maintained pH values of approximately eight. Many species of the benthic animals inhabiting the constructed shallow area were the same as those in the natural area. The species number, density, and biomass (wet weight) at the constructed sites have been more than those at the natural site. These results suggest that we have restored a shallow area that is equal or superior to the natural shallow area for benthic animals by using this construction method.
