ISSN:
1432-1793
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Biologie
Notizen:
Abstract In a series of laboratory experiments carried out during 1982, the biokinetics of 237Pu (IV), 237Pu (V), 241Am (III), and 252Cf (III) were studied in the benthic marine isopod Cirolana borealis Lilljeb. Following a 3 wk exposure to labelled seawater, isopods reached non-equilibrium concentration factors of 52±15, 54±12, 176±14, and 185±53 for Pu (IV), Pu (V), Am and Cf, respectively. Uptake of these radionuclides occurred to a great extent by surface adsorption, with the major fraction of the accumulated radionuclides being associated with exoskeleton and lesser percentages located in gut, digestive gland, muscle and haemolymph. The pattern of radiotracer depuration was in all cases biphasic, with the long-lived retention compartment retaining the largest fraction of whole-body radioactivity. Biological half-lives for radionuclide turnover in the long-lived compartment were 60±3 d, 87±5 d, 261±12 d and 288±60 d for Pu (IV), Pu (V), Am and Cf, respectively. Examination of radionuclide distribution among tissues following longterm depuration showed that the radionuclides were eliminated from internal tissues more rapidly than from the exoskeleton. Uptake and depuration studies indicated that the biokinetics of americium and californium were similar to each other, but that they differed significantly from those of oxidized and reduced plutonium. In general, these experimental results support previous reports that americium and californium are more bioavailable than plutonium in the marine waters. The fraction americium and californium assimilated into tissue from food was very low and did not exceed 5%. Unassimilated labelled food was often retained in the gut for more than 2 mo and released only infrequently in a loosely bound condition. In the event of contamination, this particular feeding-digestion strategy in highly mobile, scavenging isopods could act as a potential biological mechanism for the widespread dispersion of radioactive wastes.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/BF00392888
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