The diffusion of the 235NpO2+ and 95mTcO4−-ions has been measured directly in sample cylinders of two different sediments from the floor of the deep sea. In smectite-rich sediment not shielded from contact with atmospheric oxygen the following values were obtained for the effective diffusion coefficients of neptunyl- and pertechnetate-ions, respectively: Deff(NpO2+) = 1.5 × 10−12 m2s−1 and Deff(TcO4−) = 3.2 × 10−10 m2s−1. Under anoxic conditions in sediment with known reducing properties, the pertechnetate ion appears to undergo slow reduction and the effective diffusion coefficient of the reduced species of Deff(Tc,red)= 1.1 × 1014 m2s−1 reflects a substantial decrease of the mobility of the lower-valent technetium.
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S. Fried, A. Friedman, and F. Schreiner, A Study of the Mobility of Plutonium and Americium in Clay, Annual Report, September 1980, Sandia National Laboratory Report No. SAND 81-7114.
Based on work performed under the auspices of the Sandia National Laboratory Program Contract Number 74-1160.
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Schreiner, F., Fried, S. & Friedman, A. Diffusion of Neptunyl(V)- and Pertechnetate Ions in Marine Sediments. MRS Online Proceedings Library 6, 273–277 (1981). https://doi.org/10.1557/PROC-6-273