Remediating Explosive-Contaminated Groundwater by in situ Redox Manipulatin (ISRM) of Aquifer Sediments

The efficacy of dithionite-reduced sediments from the perched Pantex Aquifer to abiotically degrade the explosives hexahydro-1,3,5-trinitro-1,3,5-triazene (RDX), octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) and 2,4,6-trinitrotoluene (TNT) was determined. Organic matter was determined calorimetrically by chromic acid oxidation using Walkley-Black method. Extractable Fe was analyzed by extracting soil with DTAP and detecting Fe with inductively coupled argon plasma. The increase in both dithionite and buffer concentrations significantly increased RDX degradation. Fractionation of the Fe phases revealed that increasing the dithionite concentration increased the concentration of various Fe(II) species and decreased the amount of Fe(III). The buffered reduced sediments than the unbuffered reduced sediments quickly degraded the explosives RDX, HMX, and TNT.