The new evidence of phosphate minimum layer of the deep water in the Japan Sea.

Abstract

The new evidence of the existence of phosphate phosphorus minimum layer which spread over horizontally at about 2,000 m depth in the northern area from 40°N in the Japan Sea was found by the observations in March, 1964 and in July, 1969. This evidence gives us a new aspect about the circulation system of the deep water in the Japan Sea. The phosphate minimum layer was always accompanied with pH increase, but not with dissolved oxygen increase. And another interest thing is a fact that the potential temperature distribution became uniform under this layer. This suggests that a boundary layer exists and the circulation of the deep water goes two steps. From the point of view of the chemical cycle in the sea,the phosphate minimum layer brings on many problems since there are some irregularities in the oxidative ratio in this layer.