Colloid-Facilitated Transport of Radionuclides Through the Vadose Zone

In the previous reporting period, we have clarified the qualitative mineral transformation pathways when Hanford sediments are reacted with caustic Hanford tank waste. The major finding was that cancrinite, sodalite, zeolite A and allophane form when Hanford tank waste leaks into subsurface sediments. Cancrinite and sodalite are the most stable phases. The morphology and crystallinity of the minerals formed vary with alkalinity, salinity, and the Si/Al ratio. Temperature affects the reaction rates, but not the reaction pathways. In this project period, we have further refined the reaction pathways by quantification of XRD patterns and determination of weight fractions of individual minerals. This allowed us to generalize the results as function of solution chemistry