Fate, Transport and Treatment of Munitions Constituents in Soil and Groundwater

May 21, 2021

Fate, Transport and Treatment of Munitions Constituents in Soil and Groundwater

This Strategic Environmental Research and Development Program (SERDP) and Environmental Security Technology Certification Program (ESTCP) webinar focuses on Department of Defense-funded research to evaluate the fate, transport, and treatment of munitions constituents (MCs) in soil and groundwater. Specifically, investigators will present models using quantum chemical computations to estimate partition coefficients for MCs between groundwater and interacting soil and biotic phases, and discuss efforts to successfully engineer transgenic plants capable of removing MCs from soil and groundwater.

“Estimating Munitions Constitutents Fate, Transport, and Treatment Model Parameters” by Dr. Dominic Di Toro, University of Delaware

Evaluating the fate, transport, and proposed treatment designs of munitions constituents (MCs) requires models that can account for the phase distribution of the compounds being evaluated. The quantity in groundwater, soil particles, vadose zone, organisms, and plants plays a central role in the degree to which an MC bioconcentrates, is toxic, and can be treated. The parameters that determine phase distribution are the partition coefficients between the groundwater and the interacting soil and biotic phases. This presentation covers the models that have been developed using funding from SERDP to estimate partition coefficients. The partition coefficient models utilize Abraham solute parameters for the MCs and Abraham system parameters for the phase being evaluated. The reason for this choice is that after the Abraham parameters for an MC are determined, they are applicable to all the systems for which Abraham system parameters are available. This presentation will also cover MCs partitioning to soil and bioconcentration into grass and worms. Progress on methods for estimating Abraham parameters for anion MCs will also be discussed.

“Demonstrating the Efficacy of Using Genetically Modified Plants to Remediate Explosives Pollution” by Dr. Neil Bruce, University of York (UK)

Decades of military activity on live-fire training ranges have resulted in the contamination of land and groundwater by high explosives. 2,4,6-Trinitrotoluene (TNT) and its transformation products are toxic, but these tend to bind strongly to clay and organic matter in soil and are largely contained at the site of contamination. On the other hand, hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) is a major concern because of its high mobility through soils and subsequent contamination of groundwater. RDX contamination on training ranges is now proving to be a significant threat to drinking water sources. Currently, there are no cost-effective processes to contain RDX or remediate large areas of contaminated vegetated land on training ranges. In this presentation, we will discuss the molecular mechanisms behind the detoxification of explosives in plants and how we have used this knowledge, in combination with studies on the bacterial degradation of explosives, to successfully engineer transgenic plants to remediate toxic explosives pollutants. As part of this ESTCP effort, we have genetically modified military relevant plants by inserting genes into them that enable the plants to degrade RDX and detoxify TNT in soils. Field trials have been conducted at Fort Drum to demonstrate the potential of these plant systems to provide a self-sustaining, inexpensive, and environmentally friendly method to alleviate groundwater contamination. The use of this technology will allow the land to remain in use with limited closure to military activities. Specific areas that can potentially benefit from this technology are wide-ranging and include firing points, impact areas, manufacturing sites, and demolition areas.