ZVNI is one of the most extensively studied and applied engineered nanomaterials forenvironmental remediation. Despite its promising potential for environmental applications, there is a limited knowledge about the fundamental properties of ZVNI, particularly, its structure, surface composition and changes in these characteristics in the aqueous media as the nanoparticles interact with the contaminants. As such, the mechanisms of contaminant abatement, reaction kinetics, and long-term effectiveness of ZVNI-enabled remediation technology are not well understood. The overarching goal ofthis research is to understand the microstructure and surface chemistry of zero-valentnano iron (ZVNI) and how these properties influence ZVNI interactions with Cr(VI) contamination. The effect of diverse organic carbon sources on the reduction and bioavailability of Cr(VI) in contaminated soils was evaluated. Furthermore the results have demonstrated the potential value of utilizing new organic carbon sources to mitigate Cr(VI) toxicity in soils.