Effects of supercritical fluid extractions on metal ion partitioning as indicated by sequential extractions

We have studied the partitioning of stable elements and uranium to two sedi ments using sequential extractions (SE). These matrices were then subjected to supercritical fluid extraction (SFE) to attempt to remove the uranium. SEs were repeated on the material remaining after SFE to determine any chan ges in partitioning. We have confirmed that under suitable chemical conditi ons, ligand-assisted SFE can be used to extract many metal ions from such m atrices. Under the conditions we used, the "easily leachable" metals were e xtracted, but the refractory metals were not. In addition, SFE appears to r edistibute the remaining metal cations among the remaining geochemical afte r SFE treatment. Our results are presented and discussed in the context of developing decontamination strategies for contaminated soils and sediments.