Abstract
Silicate is an important nutrient in the sea. The result of observation of silicate content was obtained in 1971 aboard the observation vessel that belonged to Tokyo University. Using these results, the problem of silicate in the sea is discussed.
The concentration of silicate is small near the surface and increases with the depth. The total mean concentration of silicate is higher in the North than in the South Pacific. The relation between the apparent oxygen utilization and the content of nitrate, etc., is almost linear, but there is no regular relation with respect to silicate.
This shows that most of the silicate in the sea is produced by processes other than oxidation. In the sea, the residence time of silicate is about 10,000 years; however, due to the difference in the chemical properties, the mode of concentration of silicate in the sea is quite different from other nutrient elements.
The circulation of silicate content in the sea is also considered.
