21 Jun 2024

Iron Oxidation–Reduction Processes in Warming Permafrost Soils and Surface Waters Expose a Seasonally Rusting Arctic Watershed

Abstract: Landscape-scale changes from climate change in the Arctic affect the soil thermal regime and impact the depth to permafrost in vulnerable tundra watersheds. When top-down thaw of permafrost occurs, oxygen and porewaters infiltrate deeper in the soil column exposing fresh, previously frozen material and altering redox conditions. A gap remains in understanding how redox stratifications in thawing permafrost impact the geochemistry of watersheds in response to climate change and how investigations into redox may be scaled by coupling extensive geophysical mapping techniques. In this study, we collected soils and soil porewaters from three soil pits and surface water samples from an Arctic watershed on the North Slope of Alaska and analyzed for trace metals iron (Fe) and manganese (Mn) and Fe oxidation state using bulk and microscale techniques. We also used geophysical mapping and soil thermistors to measure active layer depths across the watershed to relate accelerating permafrost thaw to watershed geochemistry. Overall, evidence showed that Fe and Mn could be useful as geochemical indicators of permafrost thaw and release of Fe(II) from thawing permafrost and further oxidation to Fe(III) could translate to a higher degree of seasonal rusting coinciding with the warming and thawing of near surface-permafrost.

3 Feb 2020

Matrix andPUBLICATION NOTICE: Target Particle-Size Effects on LIBS Analysis of Soils

 Link: http://dx.doi.org/10.21079/11681/35374 Report Number: ERDC/CRREL TR-20-1Title: Matrix and Target Particle-Size Effects on LIBS Analysis of Soils By Samuel A. Beal, Ashley M. Mossell, and Jay L. Clausen Approved for Public Release; Distribution is Unlimited January 2020 ABSTRACT:  Laser-induced breakdown spectroscopy (LIBS) is a rapid,