Accumulation of Sr in marine organisms. II. The level of 90Sr in marine organisms from the coastal sea of Japan.

Abstract

To determine the level of 90Sr intake by marine oranisms from fallout, fish (whole body and bone), molluscan shell and brown seaweed from the coastal waters of Japan were investigated during the period from 1963 to 1971. From these observations, the 90Sr concentration factor and observed ratio were calculated. The 90Sr level in marine organisms was found to have gradually decreased since 1963 in parallel with the decrease in sea water 90Sr content: from 0.5 SU in 1963 to 0.1 in 1971 for fish bone. The concentration factors for 90Sr ranged from 12 to 109 in fish bone, from 40 to 205 in molluscan shell and from 3 to 10 in brown seaweed. The observed ratios for 90Sr were 0.40, 0.32, 0.21 and 3.54 in bone and whole body of fish, molluscan shell and brown seaweed, respectively. These figures were similar to those for stable Sr. The 90Sr specific activity in marine organisms was also comparable to that in sea water, suggesting that, for marine organisms, fallout 90Sr becomes physicochemically indistinguishable from stable Sr within a relatively short time after entering sea water.