Uranium- Phytate Interaction in Soils.

Uranium (U) contaminated soils and sediments are a major environmental concern associated with U milling and mining operations for nuclear fuel, as well as the production of materials for nuclear weapons production. For instance, U is the most widely distributed contaminant at Department of Energy (DOE) facilities. The size and complexity of many impacted sites can make remediation difficult using conventional approaches, such as excavation and disposal or pump-and-treat. In situ remediation strategies are typically less expensive and rely on the introduction of chemical additives in order to reduce migration, bioavailability and ultimately the associated exposure hazard. However, the use of in situ remediation techniques requires a fundamental understanding of the underlying geochemical processes and a commitment to long-term monitoring, as the contaminant remains in place with the potential to become a hazard at a later date. Previous experiments indicate that apatite addition to U contaminated soil results in the precipitation of secondary phosphates containing significant amounts of U and other contaminant metals, significantly reducing the solubility of U. The use of phyate (IP6) has been suggested as a more soluble form of phosphate for in situ remediation applications where applying apatite is unfeasible, such as U contamination at significant depth. The current study consists of a series of laboratory sorption experiments of increasing complexity designed to improve our understanding of the abiotic reactions controlling IP6 partitioning in highly weathered soils and aquifer sediments, and its impact on U fate and transport.