Abstract
The mechanism of eutrophication in embayments was investigated in Hakata Bay that is located on the northern part of Kyushu Island. On the basis of the results of the field survey, two numerical simulation methods for the prediction of COD concentration were discussed. The first method was the ΔCOD method in which the COD concentration derived from phytoplankton production was expressed integrally with the concentration of nutrients. The other one was the productive function method in which the rate of internal COD production was represented as the function of the concentration of the nutrients.
As a result of field survey and the numerical simulation the coefficients of sedimentation velocity, primary production rate, and decomposition rate were obtained. Thus the mass balance of COD and nutrients in Hakata Day were identified. In addition, two simple and useful methods for the COD prediction, the COD method and the productive function method, were indicated.
