Recently, the serious environmental problems are occurring in Ariake Bay which was the sea of the abundant harvest. In order to determine the effective policy about environmental and ecosystem restoration project, we developed a pelagic-benthic coupled ecosystem model for Ariake Bay and carried out hind-cast simulation during 7 years. Simulation results of hydrological features and water quality were consistent with those of observed one. Furthermore calculated concentration of dissolved oxygen indicated distinct variability in spring-neap tidal cycle and variation of hypoxia during recent 7 years from 2000 to 2006 in high accuracy. These features of calculated hypoxia water were consistent with results of many observational aspects. In order to clarify these hypoxia generation mechanisms, fluxes of dissolved oxygen due to diffusion, advection and many biochemical processed were calculated from simulation results. Calculated fluxes suggested that vertical diffusion was dominant process for oxygen supply to bottom water at Isahaya Bay and near the edge of tidal-flat at head of bay and it was controlled by river discharge through strength of stratification. On the other hand calculated oxygen consumption rate in pelagic system was larger than benthic system in hypoxia water except for near head of bay. where oxygen consumption in benthic system was not negligible. Furthermore flux analysis of biochemical processes indicated that about a half of oxygen consumption in pelagic system was caused by decomposition of POM originated by primary production. However POM production was occurred over relatively wide area, horizontal distribution of POM flux indicated the convergence area at head of bay and setting flux to sediment was dominant near this area at same time. It was considered thai oxygen consumption rate in benthic system was maintained at larger value as a result of physical accumulation of POC and respiration of benthos in these area. Therefore, transport processes of POC through the estuarine circulation plays a crucial role about generation mechanism of hypoxia water in Ariake bay.
We have developed a bioaccumulation model for operation in a Windows® PC system that predicts the levels of hazardous chemicals in an estuarine food chain. This model, called as the ” AIST-Bioaccumulation Model in Tokyo Bay for
Windows® version” was developed to estimate with high temporal and spatial resolution the concentration of chemical substances in organism. Within this model average current field, concentration of particulate organic matter and specific chemical substances in Tokyo Bay were simulated using a 3D-hydrodynamic model, an ecological model, and a chemical fate prediction model sequentially. The results of these calculations were stored in an embedded database and then used by the bioaccumulation model to predict of the concentration of chemical substances in organisms of Tokyo Bay using a PC. In addition, a user-friendly Graphical User Interface (GUI), developed using C++, was applied to set parameters for the model calculation and to visualize the results. This system includes the following functions:
• Parameter settings for predicting the concentrations of chemical substances in organisms
• Prediction of concentrations and amounts of chemical substances in organisms
• Temporal and spatial distribution display of prediction results
• Temporal variation display of prediction results al arbitrary points
• Export of prediction results; numerical value (CSV format) and output image (BMP. JPEG and WMF)
This study was carried out to search the properties of granulated blast furnace slag, which is a by-product from the
manufacturing of iron, for the settlement of planktonic larvae of Japanese littleneck clam (Ruditapes philippinarum). as well as survival and grows of its young shells. In the settling experiment of planktonic larvae, the slag showed significantly higher density of settlers than the natural sand. In the results of comparison of the natural sand, silica sand and slag, the slag showed significantly higher density of settlers than the natural sand, silica sand, whereas there was no significant difference between the natural sand and silica sand. An analysis of the interstitial water showed that pH and the concentration of Si of slag was significantly higher than the natural sand. However, concentration of Mn. Fe. Al. Zn. Ti. Cr in the interstitial water of natural sand and slag was very low. and there was no significant difference between the natural sand and slag. In hydration experiments, there was significant difference in the change of pH. Si between the slag and natural sand, silica sand. Number of larval sinking to the bottom was significantly larger on the slag as compared to natural sand, silica sand. There was no significant difference in the number of larval sinking to the bottom in pH 8.0-9.2. and also in 1.12-11.12 ppm of Si concentration. For the results of experiment of effect on survival, there was no significant difference between pH 8.0 and pH 8.9. 9.2. and also between 1.12 ppm and 11.12 ppm of Si concentration. From results of analysis of the interstitial water and liquid concentration during hydration, we were not able to confirm that Mn. Zn. Fe reported by the study of past may exert serious influence on the promoting factor
of larval settlement of slag. When the slag was covered with the natural sand 5 mm thick, the density of larval settlement was lowered. From this result, we suggested the possibility of physical characteristics of slag.
Alkalinity pump is one of the principal physicochemical pumping processes that drive the ocean carbon cycle. Although there have been several models to date that take alkalinity pump into account, they failed to reproduce relatively high biomass of coccolithophorids as well as to estimate quantitatively the CaCO;1 sinking flux. We carried out a sensitivity analysis of biomass of coccolithophorids and CaC03 sinking flux using a new ocean carbon model which includes refined functional groups of plankton and alkalinity pump. It turned out that the model with our choice for the physiological parameters result in good agreement with observations on high biomass of coccolithophorids and CaC03 sinking flux in southern ocean. There are many studies on coccolithophorids blooming in southern ocean, and our model reproduced it satisfactory.
The concentration of decaBDE used as flame retardant additives for plastic material was analyzed in Tokyo Bay. There are three resources (the atmosphere, major rivers, and direct waste water from sites) of the decaBDE loading fluxes to Tokyo Bay. We used AIST-ADMER(AIST-Atmospheric Dispersion Model for Exposure and Risk Assessment) and AIST-SHANEL (AISTStandardized Hydrology-based Assessment tool for chemical Exposure Load) to estimate the chemical loading fluxes from the atmosphere and the major rivers, developed by the National Institute of Advanced Industrial Science and Technology(AIST). And, the decaBDE concentrations were analyzed by AIST-RAMTB (AIST- The Risk Assessment Model for Tokyo Bay) in Tokyo Bay after the estimation of the chemical loading fluxes as a condition for the calculation. The concentrations of dissolved decaBDE showed a high value (0. 001 ～0. 003ng • L^-1) at Sumida riv. estuary and around the points of waste water from sites. On the contrary, the high average concentration of decaBDE, 258ng • g^-1 was estimated in sediments.