This study demonstrated the mechanical and electrical responses of Arctic saline permafrost during freeze-thaw processes, and suggested large uncertainty when estimating the unfrozen water content using electrical resistivity data.
Electrical and seismic signals during freeze thaw cycles of saline permafrost show characteristic changes with differential hysteresis behaviors. The uncertainty associated with unfrozen water content estimation based on electrical resistivity could be large.
Our study revealed low electrical resistivity and elastic moduli at temperatures down to approximately -10 °C, indicating the presence of a significant amount of unfrozen saline water under the current field conditions. The spectral induced polarization signal showed a systematic shift during the freezing process, affected by concurrent changes of temperature, salinity, and ice formation. An anomalous induced polarization response was first observed during the transient period of supercooling and the onset of ice nucleation. Seismic measurements showed a characteristic maximal attenuation at the temperatures immediately below the freezing point, followed by a decrease with decreasing temperature. The calculated elastic moduli showed a non-hysteric response during the freeze-thaw cycle, which was different from the concurrently measured electrical resistivity response where a differential resistivity signal is observed depending on whether the soil is experiencing freezing or thawing. The differential electrical resistivity signal presents challenges for unfrozen water content estimation based on Archie's law.
Lawrence Berkeley National Lab
The Next-Generation Ecosystem Experiments (NGEE Arctic) project is supported by the Office of Biological and Environmental Research in the DOE Office of Science. This research is supported through contract number DE-AC0205CH11231 to Lawrence Berkeley National Laboratory.
Wu, Y., S. Nakagawa, T.J. Kneafsey, B. Dafflon, and S. Hubbard. 2017. “Electrical and Seismic Response of Saline Permafrost During Freeze-Thaw Transition,” Journal of Applied Geophysics, 146,16-26. DOI: 10.1016/j.jappgeo.2017.08.008.
SC-23.1 Climate and Environmental Sciences Division, BER
BER supports basic research and scientific user facilities to advance DOE missions in energy and environment. More about BER
Aug 24, 2019
New Approach for Studying How Microbes Influence Their Environment
A diverse group of scientists suggests a common framework and targeting of known microbial processes [more...]
Aug 08, 2019
Nutrient-Hungry Peatland Microbes Reduce Carbon Loss Under Warmer Conditions
Enzyme production in peatlands reduces carbon lost to respiration under future high temperatures. [more...]
Aug 05, 2019
Amazon Forest Response to CO2 Fertilization Dependent on Plant Phosphorus Acquisition
AmazonFACE Model Intercomparison. The Science Plant growth is dependent on the availabi [more...]
Jul 29, 2019
A Slippery Slope: Soil Carbon Destabilization
Carbon gain or loss depends on the balance between competing biological, chemical, and physical reac [more...]
Jul 15, 2019
Field Evaluation of Gas Analyzers for Measuring Ecosystem Fluxes
How gas analyzer type and correction method impact measured fluxes. The Science A side- [more...]
List all highlights (possible long download time)