Research‎ > ‎

Permafrost soils

Permafrost thaw and trace gas exchange

Thaw chronosequence at Innoko Flats, western Alaska


MS student:
Carmel Johnston (completed August 2013)

Collaborators
Jennifer Harden, USGS
Torre Jorgenson, Alaska Ecoscience
Paul Stoy, Montana State University
Ruth Varner, University of New Hampshire
Josh Koch, USGS

Permafrost soils store over half of global belowground carbon (C), and northern hemisphere frozen peatlands store about 10% of permafrost C. Many high latitude lowland peatlands are undergoing thaw and inundation, which may increase the surface-atmosphere flux of methane (CH4), a potent greenhouse gas.

To examine the effects of lowland permafrost thaw over millennial timescales, we measured CH4 and CO2 exchange along a ~1000-y thaw chronosequence of sites at Innoko Flats Wildlife Refuge in western Alaska. We observed that CH4 emissions following lowland permafrost thaw are enhanced over decadal time scales, but limited over millennia. 

Reference

Johnston*, C. E., Ewing, S. A., Harden, J. W., Varner, R, K., Koch, J., Wickland, K. P., Manies, K., Jorgenson. M. T. (In press July 2014) Effect of permafrost thaw on CO2 and CH4 exchange in a western Alaska peatland chronosequence. Environmental Research Letters.


*graduate student advisee

Permafrost thaw and hydrologic connection

Linking soils, small catchments and big rivers in the Alaskan Interior
Ericksen Creek area, central Alaska



Collaborators
Rob Striegl, USGS
Jim Paces, USGS
Josh Koch, USGS
Jon O'Donnell, NPS
Yuri Shur, UAF
Misha Kanevskiy, UAF
Jen Harden, USGS
Torre Jorgenson, Alaska Ecoscience

Large arctic rivers can provide an integrated signal of regional permafrost thaw and associated carbon dynamics.  A long-term (30-y) decrease in dissolved organic carbon (DOC) and increase in dissolved inorganic carbon in the Yukon River Watershed (YRW) suggest increased flow through mineral soils as a result of permafrost thaw. As a post-doctoral researcher with the US Geological Survey, I used U-series isotopes and dissolved organic C (DOC) chemistry to test for the influence of thaw on soil and surface waters in small upland catchments at three sites within the YRW.

In related work, I used U-series isotopes in thaw waters from permafrost core samples to develop an approach for modeling the age of syngenetic permafrost ice in deep loess deposits.

References
Koch, J. C., Ewing, S. A., Striegl, R., and McKnight, D. M. (2013). Rapid runoff via shallow throughflow and deeper pipe flow in a boreal catchment underlain by frozen silt. Hydrogeology Journal 21, 93-106, doi 10.1007/s10040-012-0934-3.

Jorgenson M.T., Harden J.W., Kanevskiy M.Z., O’Donnell J., Wickland K., Ewing S.A., Manies K, Zhuang Q., Shur Y., Striegl R. and Koch J. (2013). Hydrologic reorganization and soil carbon changes after permafrost degradation across heterogeneous boreal landscapes. Environmental Research Letters.

Ewing, S. A., Paces, J. B., O’Donnell, J. A., Kanevskiy, M. Z., Shur, Y., Jorgenson, M. T., Aiken, G. R., and Striegl, R. (in press November 2014), Uranium isotopes in loess permafrost: modeling the age of ancient ice. Geochimica et Cosmochimica Acta.

Ewing, S. A., Paces, J. B., O’Donnell, J. A., Kanevskiy, M. Z., Shur, Y., Jorgenson, M. T., Harden, J. W., Aiken, G. R., and Striegl, R.  (in preparation), Transformation of upland water and carbon dynamics by thawing permafrost in the Alaskan Interior.  In preparation for Journal of Geophysical Research.