Study on the chemical forms of radionuclides in seawater, 1

The stability constants for sulfate, chloride and hydroxide ions with cerium (III) in the solution at ionic strength of 0.67 have been determined by cation exchange method, the values of β1 and β2 for sulfate complexes of cerium being 40 +- 13 and 453 +- 140, respectively and those for chloride complexes being 1.28 +- 0.23 and 0.56 +- 0.076, respectively. The values of β1, β2 and β3 for hydroxide complexes of cerium were (4.5 +- 0.9) x 107, (3.3 +- 0.7) x 1014 and (1.8 +- 0.7) x 1023, respectively. Using the above constants the ratios of individual chemical species of 144Ce were calculated in a solution at ionic strength of 0.67 containing sulfate and chloride ions approximately the same as in seawater of 3.5%. The result of calculation indicates that the dominant species of 144Ce in this solution is Ce(OH)30 at pH 8. (author)