The relative mobility of natural (Th,Pb and Po) and fallout (Pu,Am, Cs) radionuclides in the coastal marine environment: results from model ecosystems (MERL) and Narragansett Bay |
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| Authors: | Peter H Santschi Yuan-Hui Li Dennis M Adler Michael Amdurer Joy Bell Urs P Nyffeler |
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| Institution: | Lamont-Doherty Geological Observatory of Columbia University, Palisades, N.Y. 10964, U.S.A. |
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| Abstract: | The relative mobility of nuclides of Pb, Th, Pu, and Cs, which are widely used as geochemical tracers for sedimentation and bioturbation. was investigated in artificial microcosm tanks (MERL) and in Narragansett Bay. Their mobility was characterized by their removal rates from the water column, their affinity toward particles and their degree of penetration into the surface sediments. Pb, Th, and Pu transport was controlled predominantly by the affinity of these elements to particles, and the transport parameters of the particles themselves (i.e. sediment resuspension and mixing rates). Because of its low distribution coefficient, transport of Cs was controlled by molecular diffusion through pore water in the winter, while in summer, Cs transport was enhanced due to bioturbation. The increase with depth of the ratio in core profiles of MERL and Narragansett Bay sediments is thus caused primarily by the higher mobility of Cs. |
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