Author(s): Masahiro Seguchi; Masumi Koriyama; Osamu Kato
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Keywords: No Keywords
Abstract: Vertical diffusion coefficients in the estuarine area of western interior parts of the Ariake Sea in summer of 2006 decreased rapidly near the lower end of pycnocline. Oxygen consumption in the bottom layer of sea-water column below the pycnocline was mainly caused by aerobic decomposition of organic mutter suspended in that layer. The seasonal variations of vertical diffusion coefficient between surface and bottom layers and oxygen consumption rate in the study area, where located in the estuarine area of western interior parts of this sea, were analyzed by a two-layer box model. As a result, vertical diffusion coefficient tended to increase in summer and to decrease in winter, and its monthly variations were closely related to that of density stratification parameter. On the other hand, oxygen consumption rate tended to be positive (O_2 consumption) in summer and to be negative (O_2 production) in winter, Thus, a close relation between formation of pycnocline and occurrence of hypoxia in the estuarine area of western interior parts of this bay was shown.
Year: 2009