"Developing and Validating Genetic Catabolic Probes to Quantitatively Assess Monitored Natural Attenuation of 1,4-Dioxane" by Dr. Pedro Alvarez
Monitored natural attenuation (MNA), which relies primarily on biodegradation, is often the most cost-effective approach to manage large and dilute groundwater plumes of 1,4-dioxane. This SERDP project developed catabolic gene probes that quantify the presence and expression of 1,4-dioxane biodegradation genes to assess the site’s intrinsic bioremediation capacity and support decisions to select or reject MNA at 1,4-dioxane-contaminated sites. Although several 1,4-dioxane-degrading microorganisms have been characterized, our understanding of the environmental distribution and metabolic diversity of these 1,4-dioxane degraders is far from complete. Using an archetype 1,4-dioxane degrader, we developed gene probe thmA, which detects 1,4-dioxane biodegradation activity at contaminated sites. The thmA probe was used to label and isolate DNA to identify putative 1,4-dioxane degraders from contaminated sites. Given the types of microorganisms identified, the thmA probe alone likely underestimates 1,4-dioxane biodegradation. Accordingly, we identified a propane monooxygenase gene cluster (prmABCD) involved in 1,4-dioxane metabolism in another archetype 1,4-dioxane degrader and developed gene probe prmA. Used together these probes can help assess the presence of 1,4-dioxane degraders at contaminated sizes with high selectivity and high sensitivity. Overall, these results suggest that catabolic gene probes are a valuable tool to help determine the feasibility and assess the performance of MNA to manage 1,4-dioxane plumes.
"New Developments in Managing 1,4-Dioxane Sites: Do We Have the Right Conceptual Site Model?" by Dr. David Adamson
New research is changing our understanding of how 1,4-dioxane behaves following its release to the environment. This SERDP-sponsored project helped develop a more informed conceptual model and treatment strategy for 1,4-dioxane at contaminated groundwater sites. A combination of data mining, modeling, bench-scale studies, and field-scale studies was used to address the project objectives. Dilute plumes and matrix diffusion were confirmed as challenges to using conventional treatment technologies at 1,4-dioxane sites. Because of these processes, 1,4-dioxane sites may lack an easily-targeted source zone for active treatment. In combination with evidence of 1,4-dioxane attenuation and shorter plumes, the project findings highlight the potential utility of natural attenuation as a site management option. The corroboration between field and lab data collected during this project suggests that biological degradation of 1,4-dioxane is promising at sites that require active treatment due to regulatory or risk drivers. This project also tested a series of treatment trains to demonstrate that particular technology combinations (e.g., in situ chemical oxidation with bioaugmentation) may be a promising approach at these sites, particularly sites with co-occurring 1,4-dioxane and chlorinated solvents.
Dr. Pedro Alvarez is the George R. Brown Professor of Civil and Environmental Engineering at Rice University where he also serves as the director of the National Science Foundation (NSF) Engineering Research Center on nanotechnology-enabled water treatment. Dr. Alvarez’ research interests include environmental implications and applications of nanotechnology, bioremediation, fate and transport of toxic chemicals, water footprint of biofuels, water treatment and reuse, and antibiotic resistance control. Pedro was elected to the National Academy of Engineering in 2018 for contributions to the practice and pedagogy of bioremediation and environmental nanotechnology. Previously, he was awarded the 2014 American Academy of Environmental Engineers and Scientists Grand Prize for Excellence in Environmental Engineering and Science and honored as the 2012 Clarke Prize laureate. He is a past president of the Association of Environmental Engineering and Science Professors and currently serves on the advisory board of the NSF Engineering Directorate and on the editorial board of Environmental Science and Technology. Dr. Alvarez is also a past member of the United States Environmental Protection Agency’s Science Advisory Board and an honorary professor at Nankai University, Zheijan University, the Chinese Academy of Sciences in China, and the Universidade Federal de Santa Catarina in Brazil. He received a Bachelor of Engineering degree in civil engineering from McGill University and master’s and doctoral degrees in environmental engineering from the University of Michigan.
Dr. David Adamson is a principal engineer with GSI Environmental in Houston, Texas. Since joining GSI in 2004, his practice areas include research and development, site investigation, characterization and remediation. He has extensive expertise in natural attenuation, source zone characterization, emerging contaminants, matrix diffusion, and the development and testing of innovative treatment technologies, with projects in the United States, Europe, Latin America and the Middle East. He has served as a principal investigator or co-principal investigator on multiple Department of Defense-sponsored research projects, including those focused on 1,4-dioxane, per- and poly-fluoroalkyl substances, innovative long-term monitoring approaches, enhanced amendment delivery systems, and improved characterization and treatment methods for contaminants in low permeability matrices. He was a co-instructor for the recent ESTCP Massive Open Online Course on natural attenuation. Dr. Adamson earned his doctoral degree in civil and environmental engineering from the University of Iowa in 2000. He also worked as a post-doctoral research associate at Cornell University, and has held the positions of research scientist and adjunct assistant professor at Rice University. He currently serves as a lecturer in the Civil and Environmental Engineering Department at Rice University. Dr. Adamson is a licensed professional engineer in the state of Texas.