Cr(VI) Behavior In Subsurface Soil From Savannah River Site Through Laboratory and Modeling Efforts.

A mechanistic understanding of Cr behavior in the subsurface environment is essential to the development of effective remediation strategies. Cr occurs primarily in two redox states, the relatively immobile trivalent form, Cr(III), and the toxic, more mobile, hexavalent forms, chromate (CrO₄^2-) or dichromate (Cr₂O₇^2-). The fate of Cr depends greatly on its chemical speciation in response to local geochemical conditions. Thus, in this study, detailed Cr(VI) behavior was investigated using controlled batch and column experiments, the results of which  were used in the development of a conceptual model accounting for various relevant sorption reactions. The importance of various chemical processes was then confirmed through the simulation using a geochemical code, PHREEQC-2.