| 英文摘要: | Dr. Stephanie R. James has been awarded an NSF EAR Postdoctoral Fellowship to carry out a research and education plan at the U.S. Geological Survey, Crustal Geophysics and Geochemistry Science Center, in Denver, CO. Her research project will improve the understanding of how Arctic boreal peatlands respond, both physically and chemically, to thawing permafrost. The release of permafrost carbon has the potential to impact the global carbon budget. However, the magnitude of this impact is uncertain due to the complex relationships between processes above and below ground, dramatic seasonal changes, and limitations in subsurface measurement capabilities. Dr. James will use a novel combination of geophysical and biogeochemical techniques in a multidisciplinary field experiment near Fairbanks, Alaska to improve the understanding of the physical controls on carbon fluxes at the site scale. This will lead to improved predictions of the permafrost-carbon feedback in climate models at the global scale. In addition, this project will advance a passive seismic technique capable of continuous monitoring for permafrost degradation, which could improve infrastructure security in local communities. Dr. James will also conduct an education plan to advance academic and professional scientific inquiry and public education. A multiday geophysical workshop will train college graduates and professionals in cutting-edge hydrogeophysical methods. Then, a series of Earth science outreach visits to middle schools in Denver, CO and Fairbanks, AK will broaden student awareness and encourage science participation.
This project entails a one year multidisciplinary field experiment and the integration of field data with numerical simulations of water and energy transport using the code SUTRA 3.0. Passive seismic, nuclear magnetic resonance, temperature, soil moisture, and carbon flux measurements will be collected along a transect between intact permafrost and a collapse-scar bog. By using a unique combination of geophysical and biogeochemical methods, this project will address how subsurface physical processes, such as seasonal freeze-thaw dynamics and changes in water content, impact carbon exchange with the atmosphere across a permafrost thaw gradient. Numerical modeling will improve the understanding of relationships between surface conditions and subsurface processes, as well as aid with interpretation of seismic velocity changes. This work builds off previous studies of the Alaskan Peatland Experiment (APEX) and will advance passive seismic techniques for permafrost monitoring. |