Occurrence of hypoxic water and density stratification in the western interior parts of the Ariake Sea
2007
Ishitani, T.(Kagoshima Univ. (Japan)) | Seguchi, M. | Koriyama, M. | Kato, O.
In the present study, the occurrence situation of hypoxic water which has bad influences on the ecosystem and fishery in the interior parts of the Ariake Sea, and the relationships between its occurrence and density stratification in the sea water were investigated on the base of field observation data. As a result, it was clarified that the hypoxic water in the bottom layer occurred frequently at the neap tide during summer when wave height was low and the sea was calm in the interior western parts with high COD and mud content, and the decrease of supply of oxygen from the upper layer to the lower one owing to the fall of vertical diffusion coefficient between the upper layer and the lower one with the formation of density stratification contributed to the occurrence of hypoxic water greatly. Moreover, seasonal variations of degree of density stratification, vertical diffusion coefficient and consumption rate in the lower layer ware grasped by the analysis of field observation data using a two-layer box model.
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