Driving forces of seawater current in the Tokyo Bay have several factors including the tide, the density structure, the river inflow and others. On the other hand, many power plants of total output of 185.4 MW (as of 1995) are located along the coast of the bay, together with a large number of factors which load the sea area with cooling water and heat. Although these facilities might be considered to affect water current in the bay, few studies have been made on the effects which these artificial inputs may exert on water current. The present study reports computation results, using a 3-dimentional current model on effects of water intake and effluent by a possibly increasing number of power plants on the current in the bay. It was concluded that an additional power plant output of 103.1 MW (corresponding to increase of cooling water by 30% and of heat load by 20% from the present levels) might bring about only slight changes except for altered water current and temperature in the vicinities of power plants of which power output were increased. Average temperature rise of 0.1 °C was also predicted in the surface water throughout the bay.
The effect of topographic mesh size and correction range on a terrain correction is examined by a simple stacking method of rectangles formed by mesh data of 10", 20",30", and 60" intervals, respectively. This examination shows that the mesh size affects seriously over steep gradient areas shallower than 500m depth. This fact suggests that data with finer mesh size is required for the approximation of topography near the observation point. To meet this requirement, a new method to approximate the topography near the observation point is developed: for the nearest region (within the basic mesh including the observation point), the mesh is divided into sub-meshes in accordance with depths and slopes near the observation point: for the near region surrounding the nearest region, the area is divided into 12 blocks of 1/2-size of the basic mesh. The depths at the centers of these sub-meshes are automatically interpolated from the depths at the adjacent grids and the observed point. By using the above method, the accuracy of terrain correction is improved to as much as 0.7mGal in the case of division number 8. Bouguer gravity anomalies in Suruga Bay were calculated by this method, which may reveal fine structures of Suruga Bay.
Pressure and temperature characteristics of in-situ sensors have a big influence on measurements. A pH sensor using ISFET (Ion Sensitive Field Effect Transistor) is regarded as a suitable sensor for measurement pH at deep sea, however, its pressure and temperature characteristics were seldom studied. So, in this paper, we study the pressure and temperature characteristics of ISFET-pH sensor by the structural analysis and by the laboratory experiments, and then consider a new structure which can decrease the pressure effects on ISFET-pH sensor, and investigate these effects on the actual measurement in deep sea. From experimental and actual measurement results, we estimate the applications and efficiency of ISFET-pH sensor. By the results of structural analysis, if the structure of the sensor has sufficient strength for practical use, pressure effects occur. The experimental results shows the pressure and temperature characteristics have large individual difference. But by the results of structural improvement analysis, the pressure effects can be reduced by the change in construction material of the sensor. The actual measurement in deep sea indicates that the temperature characteristics depends on pressure, and show a problem of the present way of calibration that is to calibrate the effects of pressure and temperature, respectively.At the same time, it is also shown that the sensor has high sensitivity, good responsibility, wide application and good efficiency.
In recent years, research has been underway to clarify the fate of radioactive waste dumped into the Kara Sea and the Barents Sea of the Arctic Ocean. These sea areas are very narrow, shallow and located close to land. Using the observation data (water temperature and salinity), the flow was analyzed using a hybrid box model, taking into account river flows and density structures in the seas (Wada 2002). In this paper, using the results of flow analysis, concentration analysis is conducted on the basis of a release scenario with considerations given to nuclide decay, mixing, scavenging and interaction between undersea particles and the bottom sediment layer. Especially, sensitivity analysis is conducted on Pu239 and Cs-137 using distribution coefficients, the concentration of suspended solids (SS) in the ocean, and the settling velocity of suspended load as parameters.