Stage-dependent uptake of cadmium by Bufo arenarum embryos

The uptake of cadmium at 4 different post hatching stages in Bufo arenarum, from the appearance of cardiac beat to the end of embryonic development was studied. Embryos were exposed to concentrations of 0.06-0.50 mg cadmium per litre, rising to 3.0 mg per litre for complete operculum in the final stage for 15-240 minutes. At the end of exposure the embryos were acid-digested and cadmium determined by atomic absorption spectrophotometry. The concentration of cadmium per embryo was much greater for the last stage of development. The longer the last development stage was exposed to cadmium the higher the concentration in the embryo; accumulation in the other stages was not greatly affected by time. At concentrations of 0.12 mg cadmium per litre and above, accumulation of cadmium did not increase significantly with concentration except for the last stage after 240 minutes for which the increase was steady.