Published online by Cambridge University Press: 10 February 2011
At the Finnish candidate sites for a nuclear waste repository calcite (CaCO3) is a common fracture mineral, that may participate in coprecipitation processes. The objective of this work was to study the coprecipitation of the trace element Ni with CaCO3 under controlled conditions. The experiments were carried out at 30 °C in vessels closed to the atmosphere. Calcite-saturated 0.05 M NaCI solutions containing trace amounts of Ni2+ were contacted with calcite for periods of up to 42 days. The experimental data indicate that Ni coprecipitates with calcite as a result of recrystallization. The amounts of coprecipitated Ni and recrystallized calcite were determined using liquid scintillation counting and the isotopes 63Ni and 45Ca. The results are supported by a complementary SEM/EDS analysis of the solid phase.