Accumulation and retention of antimony-125 in the short-necked clam.

Abstract

Accumulation and retention of 125Sb by short-necked clam Tapes japonica were investigated in order to elucidate the uptake mechanism of the nuclide in marine bivalves. It was found that the accumulation of 125Sb by the clam from the environmental water showed an initially relative rapid increase, followed by a gradual increasing pattern during the experimental period. The concentration factors for 125Sb in the clam at the end of the experimental period were obtained as 1.2 for the soft part and 4.2 for the shell. The loss of 125Sb accumulated in the whole clam showed an initial decrease, followed by two slow elimination patterns. The long-lived biological half-life for 125Sb in the clam was approximately 58 days. Regarding the influence of chelating agent and co-existing element on the accumulation of 125Sb by the clam, it was observed that the addition of stable antimony to the rearing sea watere enhanced the accumulation of 125Sb by the soft part and shell of the clam to some extent; whereas, the accumulation of 125Sb by the soft part and shell was not depressed in the presence of EDTA. The accumulation of 125Sb by the shell depends mostly on the surface adsorption phenomenon rather than that via metabolic process.