2023 年 57 巻 2 号 p. 179-189
Vitamin B12 (cobalamin) is a micronutrient involved in various metabolic processes in the ocean, such as the citric acid cycle and DNA synthesis. In oceanography, the distribution and function of vitamin B12 have been investigated mainly in coastal areas since the 1950s, but the concentration level is extremely low at the 10-14–10-10 molar level, so, there are many unclear points about its oceanic cycle compared to major nutrients and trace metal elements. On the other hand, with the recent development of chemical analysis and gene analysis techniques, its importance is gradually reconfirmed. This paper outlines the findings obtained so far regarding the dynamics of vitamin B12 in the ocean and extracts future issues for research on marine vitamin B12.