To clarify the effect of chemical form on the accumulation of Co by organisms, a rearing experiment was performed, using ⁶⁰ Co (CoCl₂) as an inorganic compound and ⁵⁷ Co cyanocobalamin as an organic one. The concentration factor of inorganin ⁶⁰ Co for Gomphina melanaegis was calculated to be 360 and that of organic ⁵⁷ Co was 650. The effect of the difference of chemical form was not large in the accumulation of Co by bivalves. The excretion curveof ⁶⁰ Co consisted of one component, while that of ⁵⁷ Co by bivalves. The effective half of ⁶⁰ Co was 31 days and that fo the longer component of ⁵⁷ Co in the body of G. melanegis was 98 days. A remarkably different distribution of Co was observed in the gills, liver, and kidney, suggesting different metabolism processes dus to the chemical forms in the organs of the bivalves.
On the gel filtration profile of Co in the liver of G. melanaegis, inorganic ⁶⁰ Co was incorporated in two constituents and organic ⁵⁷ Co was in one compounent. Four species of bivalves G. melanaegis, Tridacna crocea, Spisula sachalinensis and Patinopecten yessoensis showed two peaks of ⁶⁰ Co in the gel filtration profiles of their livers, while Anadara broughtonii and japonica showed three peaks.