抄録
Seasonal characteristics of the spatial distributions of COD and DO in Tokyo Bay were revealed by applying statistical methods to the monitoring data obtained at 41 observation points every month from April 1985 to March 1990.
High concentrations of COD and DO in the surface layer were observed at the head and along the west coast of the bay during late spring to early autumn. They were especially prominent in June off the mouth of the R. Ara, where nutrients were abundant and phytoplankton multiplied rapidly. On the other hand, the concentration of COD in the bottom layer was higher near land than offshore, and was almost inversely proportional to depth at the head of the bay. A lower concentration of DO in the surface layer was observed off the mouth of the R. Ara than off the mouths of the R. Edo and R. Tama. The concentration of DO in the bottom layer at the head of the bay decreased at a rate of about 1 mg·l-1 per month during spring to early summer, and reached a level lower than 1 mg·l-1 in September. Furthermore, the strengthening of the wind from the northeast in September caused a drop of the concentration of DO in the bottom layer in the northeastern part of the bay.
