Presented on November 3, 2022 - Presentation Slides
“Munitions Constituent Transformations Quantified Using Enriched Stable Isotope Tracers” by Dr. Craig Tobias (SERDP Project ER19-1054)
This project supports SERDP’s efforts to provide DoD with novel tools and approaches for evaluating natural attenuation of MC as a remedial option for contaminated surface and/or ground waters. Stable isotope-labeled munitions constituents (MC) are used under simulated in-situ conditions or in field settings to derive kinetic parameters of sorption, degradation, and complete mineralization to inert end products. This stable isotope tracer approach is applied to a range of different aquatic settings to evaluate environmental factors that enhance biological degradation of MC. Results from this work provide much needed parameterization for building MC fate and transport models by addressing the following challenges with parameterizing loss: (1) using the appropriate kinetics governing loss from overlying water, retention of parent/derivative compounds in sediments, and mineralization; (2) identifying what system characteristics or environmental conditions could be used as proxies for functionalizing processes in model-space; and (3) establishing uncertainties in rates/constants. The stable isotope tracer technique provides high-sensitivity direct quantification of MC transformation, and the approach developed in this project can serve as a template for quantifying transformations of other contaminants in other environments.
“Munitions Constituents Management on Ranges: Optimizing Carbonaceous Amendments for Simultaneous Adsorption and Hydrolysis” by Dr. Wenqing Xu (SERDP Project ER19-1239)
High concentrations of MC residues, including legacy and insensitive high explosives, are commonly found in soil at DoD testing and training ranges, posing a significant safety threat to personnel. These chemicals also represent a significant source of contamination to ground and surface waters at ranges. Historically, carbonaceous amendments have been used to remove contaminants from the aqueous phase by adsorption or complexation, but not to bring about their degradation. This presentation will demonstrate that carbonaceous amendments not only adsorb, but also catalyze the hydrolysis of some MC, such as 2,4-dinitroanisole and nitroguanidine, under environmentally relevant conditions. The combined approach of experimentation and computational modeling has allowed the identification of the structural features of carbonaceous amendments that facilitate MC hydrolysis and adsorption as well as gain a fundamental understanding of this novel surface process.
Dr. Craig Tobias is a professor in the Department of Marine Sciences at the University of Connecticut. He has served as the principal and co-principal investigator of projects funded by SERDP, National Science Foundation, National Oceanic Atmospheric Administration, Environmental Protection Agency, Naval Facilities Engineering Systems/Engineering and Expeditionary Warfare Center, U.S. Army Corps of Engineers, U.S. Department of Agriculture, and others. Dr. Tobias has been recognized for excellence in research and teaching including a National Research Council Fellowship and the SERDP Environmental Restoration Project of the Year Award in 2016 for his work on legacy munition constituents behavior in coastal systems. He has served on several advisory panels including the Long Island Sound Technical Advisory Committee, SERDP’s Executive Advisory Committee for the Defense Coastal & Estuarine Research Project (DCERP) and the Connecticut Academy of Science and Engineering. He has also served as an associate editor for the journal Estuaries and Coasts. His research portfolio spans the broad topic of pollutant fate and transport along the aquatic continuum from watersheds to the continental shelf. His work targets agricultural and urban-derived contaminants as well as legacy and next generation munitions constituents in surface and groundwater. Dr. Tobias received a bachelor’s degree in biological sciences from the University of Delaware and a doctoral degree from the College of William and Mary, School of Marine Science.
Dr. Wenqing Xu is currently an associate professor in the Department of Civil and Environmental Engineering at Villanova University in Pennsylvania. The central focus of her research program is to better understand the various ways that nature detoxifies contaminants by the integration of chemical, biological, and material sciences approaches to (1) attenuate pollutant transport and thereby protect source water and (2) degrade contaminants with novel materials to provide safe drinking water. Dr. Xu has served as a principal and co-principal investigator of projects funded by SERDP, the National Science Foundation, the National Institute of Environmental Health Sciences, and the Environmental Protection Agency on research involving the development of reactive adsorbents for pollutant abatement, such as chlorinated solvents, pesticides, munitions constituents, PFAS, and disinfection byproducts. She is a recipient of various awards, including the National Science Foundation Early Career Development Program (CAREER) award in 2018 and the University Scholarly Achievement Award in 2020. She is active in several professional engineering associations and serves as the associate editor of the American Society of Civil Engineers Journal of Environmental Engineering. She received a bachelor’s degree in environmental engineering from Nankai University in China, a master’s degree in geography and environmental engineering from Johns Hopins University, and doctoral degree in chemical and environmental engineering from Yale University.