ENVIRONMENTAL CHARACTERISTICS OF SEDIMENT IN ISAHAYA BAY

Abstract

  The secular variations of environmental characteristics of sediment in Isahaya Bay were investigated on the basis of the data for 20 years from 1989 to 2008 obtained by the Kyushu Regional Agricultural Administration Office. The sediment grain size tends to be fining and the sulfide in the sediment is increasing after the construction of the reclamation dike. The authors sampled undisturbed sediment cores at 22 observation sites in Isahaya Bay in the summer of 2008 and investigated the spatial distributions of the environmental quantities. The organic pollution spreads over the whole region of Isahaya Bay and the sediment environments deteriorate extremely behind the south side of the reclamation dike. The comparison was made between the sediment environments in Isahaya Bay and in the innner are of Ariake Sea and it revealed that the sediment environments of Isahaya Bay in the summer of 2008 were much worse than those in the inner are of Ariake Sea in the summer of 2004.