Uptake by benthic algae of critical radionuclides to be released in the liquid effluent of the Angra dos Reis Nuclear Power Plant, R.J., Brazil

In vitro interaction of benthic algae from the Angra dos Reis region, R.J., Brazil, was studied with critical radionuclides to be released in the liquid effluent of CNAAA (unit I). 137Cs-60Co - and 125I uptake and loss by Sargassum filipendula, Padina Vickersiae and Acanthophora Spicifera were observed. Biological half-lives and bioaccumulation factors (B.F.) were estimated. Co and I uptake were fast (apparent equilibrium in 3 to 7 days). Cs uptake was slower (2 to 3 weeks). Loss followed an inverse pattern (fast for Cs, slow for Co and I). B.F. ranged from 101 for Cs, to 103 for I and 103-104 for Co. Higher B.F. for Co and I were found for P. vickersiae (up to 1,4 X 104) an A. spicifera (up to 7 X 103) respectively. These species represent important potential media for the transference of Co-I-and-to a much lesser extent - Cs isotopes, through food-webs. They exhibited high capacity to compete with local sandy sediments for the retention of Co and I. High B.F., rapid uptake and moderate to long biological half-lives enable S. filipendula, P. vickersiae and A. specifera to be powerful aids in the monitoring of radioactive contamination by Co and I isotopes. Since the majority of marine organisms tends to exhibit Cs B.F. similars to those reported here, these algae may also be used as monitors for Cs isotopes, the low B.F. being compensated by their abundance, wide distribution and facility of collection. (M.A.)