Objective

Exploiting humification-immobilization in soil carbon cycles.

Hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX), an explosive used in a variety of munitions and currently found in soils at training ranges, is a contaminant of concern for the Department of Defense (DoD). Low-order and incomplete detonation has resulted in the surface distribution of RDX that is both heterogeneous and widely dispersed. RDX leaching from contaminated surface soils on ranges has been implicated in groundwater contamination. Due to the need for continued training and the hazard of unknown unexploded ordnance on ranges, few remediation strategies are considered safe and applicable to remediate RDX contamination. Two low-cost approaches, natural attenuation and phytoremediation, are increasingly viewed as acceptable treatment technologies; however, a critical concern is the permanence of the remediation. Dissolved RDX has been shown to undergo a series of reductive transformations under sufficiently reduced conditions in soil, yet surface soils are generally well aerated and become wet only ephemerally. As such, surface soils on ranges can serve as an RDX source from which surface and subsurface waters become contaminated. A potential treatment technology ties together phytoremediation and photodegradation in the plant tissue and humification of plant tissue-associated RDX residues that return to the soil following plant senescence.

This project will improve the understanding of RDX transformation in plant tissues and the subsequent cycling of tissue-associated RDX and daughter products among soil mineral and humic fractions following plant senescence.