NUTRIENT ADSORPTION BY BOTTOM MUD OFF TAKESAKI OF ARIAKE SEA

Abstract

On the basis of the idea that the low release of ammonium (NH₄-N) observed in the seabed surface off Takesaki of Ariake Sea may be caused by the nutrient adsorption due to the bed materials, mud cores were sampled off Takesaki and the quantities of pore water were investigated through laboratory experiments. The oxygen consumption and the concentrations of NH4-N and phosphate (PO₄-P) were also measured through the experiments of mud resuspension. Though the concentrations of NH₄-N and PO₄-P increased with the depth from the surface of the mud core, they began to decrease after taking maximum values at some depths. The vertical profiles were very different from those seen in ordinary mud. The experiments of mud resuspension showed that the concentrations of NH₄-N and PO₄-P were kept constant though DO was consumed. These experimental results support the possibility that the high nutrient adsorption by the bottom mud occurs off Takesaki of Ariake Sea.