東京湾における懸濁物の化学的特徴

抄録

Six stations in Tokyo Bay were selected for studying the vertical and seasonal variations in the particulate matter chemistry. In summer the suspended particles above the thermocline were abundant in organic matter, and below the amount of the particles drastically diminished. In winter season the suspended particles enrichde with inorganic matter-mostly derived from the sea floor by the action of wind-driven mixing-distributed homogeneously throughout the water column.
The avaiable silica depletion in the euphotic zone during summer within the Tokyo Bay ecosystem, which is highly eutrophied by phosphorus and nitogen compounds, was observed to act as a limiting factor for the diatom growth: diatoms will be replaced, at least partially, by other phytoplankton that do not consume silica because diatoms will not be able to compete with green and blue-green algea for avaiable pools of other nutrients when the silica supply is limited. Accordingly the ratios of biogenic silica to organic carbon in the suspended matter were changed markedly.
The high constructions of reactive-silica and-phosphate in the bottom waters during summer suggested the fact that the nutrients liberated from the moiety of plankton accumulated on the bottom floor had their upward diffusion blocked by the presence of a discontinuity layer.