Summary
The solubility of U(IV) amorphous precipitates was measured in Boom Clay water in the presence of reducing agents and under the in situ partial pressure of CO2(g) at 10-2.4 atm. Boom Clay pore water is of the sodium bicarbonate type (NaHCO3 ∼ 10-2 M) and contains about 100 mg l-1 of dissolved organic carbon. The total U concentration measured after two-months equilibrating time and the 0.45 μm filtration was about 10-6 M and higher. This concentration is about 3 orders of magnitude higher than literature data for U(IV) solubility and may suggest the existence of colloids and/or U(VI) species. The U concentration was found decreasing as a function of time within the experimental period. Further experiments are currently performed to evaluate the contribution of the colloids and the role of organic matter.
© 2004 Oldenbourg Wissenschaftsverlag GmbH
