Application of Environmental Tracers in the Analysis of Flow in Discontinuous Permafrost Aquifers
Monday, December 4, 2017: 2:30 p.m.
102 B (Music City Center)
Bridget Eckhardt
,
Water and Environmental Research Center, University of Alaska Fairbanks, Fairbanks, AK
David Barnes, Ph.D., PE
,
Water and Environmental Research Center, Department of Civil and Environmental Engineering, University of Alaska Fairbanks, Fairbanks, AK
Michelle Barnes
,
Water and Environmental Research Center, University of Alaska Fairbanks, Fairbanks, AK
Ronald Daanen, Ph.D.
,
Division of Geological & Geophysical Surveys, Alaska Department of Natural Resources, Fairbanks, AK
Groundwater systems and flow dynamics in cold regions are dictated by the presence of perennially frozen ground (permafrost) and seasonal freeze-thaw dynamics. Permafrost acts as a barrier to flow and a separation between aquifers above and below the permafrost. The complexity of groundwater flow in these systems increases in the discontinuous permafrost region where perennially thawed zones (open taliks) allow for connections between supra (above)- and sub (below)- permafrost groundwater which differ in quality and composition. This complexity poses difficulties in estimating groundwater quantity and quality and developing solutions for contaminant remediation. Changes in groundwater flow are expected to occur with the formation of new taliks, as a result of the warming climate. Knowledge of groundwater dynamics in these complex systems is crucial to groundwater sustainability and the future of groundwater modeling in Arctic and sub-Arctic regions of the world.
We present two studies focused on floodplain and sub-lake taliks in Interior Alaska that use chemical and physical tracers to characterize seasonal groundwater flow dynamics of supra- and sub-permafrost groundwater in discontinuous permafrost aquifers. Results from our study of the Tanana River floodplain near Fairbanks show that stable water isotopes, deuterium (δ2H) and oxygen-18 (δ18O), can be used to distinguish supra- and sub-permafrost groundwater. At a different study site consisting of two lakes with varying degrees of talik formation in the Goldstream Creek Basin near Fairbanks we combine the analysis of major cations and anions, alkalinity, basic field parameters, and stable water isotopes to distinguish sources of water and contributions to the lakes. Both studies demonstrate the complexity and seasonal variability of flow dynamics in open taliks as well as provide several conceptual models for the flow of groundwater within open taliks that can be used as a baseline for groundwater models in discontinuous permafrost regions.
Bridget Eckhardt, Water and Environmental Research Center, University of Alaska Fairbanks, Fairbanks, AK
Bridget Eckhardt is a student studying environmental engineering at the University of Alaska Fairbanks. She received her bachelors degree from the University of California, Irvine and has experience working with the California Regional Water Quality Board and with The Westmark Group, a private consulting firm focused on groundwater remediation. Her research interests focus on groundwater quality and contaminant transport in cold regions. She is particularly interested in remediation challenges posed by frozen ground and permafrost.
David Barnes, Ph.D., PE, Water and Environmental Research Center, Department of Civil and Environmental Engineering, University of Alaska Fairbanks, Fairbanks, AK
David Barnes is a Professor of Environmental Engineering in the Department of Civil and Environmental Engineering and the Water and Environmental Research Center at the University of Alaska Fairbanks. He teaches and performs research in the area of environmental engineering specifically as the topic pertains to contaminated soil and groundwater. Over the last 14 years Barnes has focused his research on protection of human health and environmental quality in cold regions.
Michelle Barnes, Water and Environmental Research Center, University of Alaska Fairbanks, Fairbanks, AK
Michelle Barnes grew up in the Reno-Tahoe area. Her love of the outdoors was influential in pursuing degrees in Environmental Engineering. Michelle received a bachelors degree from the University of Nevada, Reno and a masters degree from University of Alaska Fairbanks. While in Alaska, she investigated groundwater dynamics in degrading, discontinuous permafrost and the impacts on contaminant transport. Michelle also worked as a research assistant at Utah State University studying groundwater-surface water interactions and is now gaining experience in regulatory work with the State of Nevada.
Ronald Daanen, Ph.D., Division of Geological & Geophysical Surveys, Alaska Department of Natural Resources, Fairbanks, AK
Ronald Daanen is a Geohydrologist for the State of Alaska, where he is responsible for the Geohydrology Program. The program strives to quantify groundwater resources in Northern Alaska through state of the art hydrological research. The complexity of quantifying groundwater flow in permafrost dominated regions, the lack of available data, and a strong dependency on climate change, requires a strong focus on thermal aspects of the landscape and utilization of geophysics to map the subsurface. The program relies on state of the art physically based coupled heat and mass transfer models to resolve groundwater availability from sparsely measured hydrological data.
