Evaluation of body size and temperature on 137Cs uptake in marine animals

Cs-137 bioaccumulation and retention in seven different marine animal species, including crustaceans, mollusc larvae, and fish larvae were compared under different temperature conditions (10 degrees C, 18 degrees C and 25 degrees C). Replicate animals were experimentally exposed to 0.5 nM Cs-137 dissolved in filtered seawater for 3 days, and their Cs-137 contents were periodically measured using gamma spectrometry. Among the seven species, Cs-137 bioconcentration factors ranged from 14 to 239 at the end of the exposure periods. Following uptake, the Cs-137 loss rate constants from the animals ranged from 5 to 50% d(-1) and were unaffected by temperature or animal size. The Cs-137 bioconcentration factors were directly related to animal size and hence their surface: volume ratios, consistent with the conclusion that Cs sorption from the aqueous phase is the principal uptake mechanism in these animals. With the exception of gastropods, temperature had no major influence on Cs uptake and efflux in the experimental species.