Late season mobilization of trace metals in two small Alaskan arctic watersheds as a proxy for landscape scale permafrost active layer dynamics

Amanda J. Barker*, T. A. Douglas, A. D. Jacobson, J. W. McClelland, A. G. Ilgen, M. S. Khosh, G. O. Lehn, T. P. Trainor

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

54 Scopus citations

Abstract

Increasing air temperatures in the Arctic have the potential to degrade permafrost and promote the downward migration of the seasonally thawed active layer into previously frozen material. This may expose frozen soils to mineral weathering that could affect the geochemical composition of surface waters. Determining watershed system responses to drivers such as a changing climate relies heavily on understanding seasonal controls on freshwater processes. The majority of studies on elemental concentrations in Arctic river systems have focused on sampling only from spring snowmelt to the summer season. Consequently, there remains a limited understanding of surface water geochemistry, particularly with respect to trace metals, during late fall and early winter. To examine the variability of metal concentrations as a function of seasonality, we measured trace metal concentrations from spring melt to fall freeze-up in 2010 in two high Arctic watersheds: Imnavait Creek, North Slope, Alaska and Roche Mountanee Creek, Brooks Range, Alaska. We focused on aluminum (Al), barium (Ba), iron (Fe), manganese (Mn), nickel (Ni) and zinc (Zn). Concentrations of 'dissolved' (<. 0.45. μm) Al, Ba, Fe, and Mn in Imnavait Creek waters and Ba in Roche Mountanee waters were highest in late fall/early winter. To link observed surface water concentrations at Imnavait Creek to parent soil material we analyzed the elemental composition of a soil core from the watershed and tracked the soil temperatures as a function of time and depth. The results from this study show a distinct seasonal signature of trace metal concentrations in late fall that correlates with the depth of the thawed active layer.

Original languageEnglish (US)
Pages (from-to)180-193
Number of pages14
JournalChemical Geology
Volume381
DOIs
StatePublished - Aug 14 2014

Funding

Funding for this project was from the U.S. National Science Foundation , Office of Polar Programs to Douglas (# 0806714 ), Jacobson (# 0806643 ) and McClelland (# 0806827 ). Toolik Field Station of the University of Alaska Fairbanks-Institute of Arctic Biology and CH2MHill Polar Field Services provided logistical support. Numerous students and collaborators are acknowledged on this project for field and laboratory assistance. Soil horizon profiles were provided as part of a field workshop on Arctic Soils offered by the University of Alaska Fairbanks taught by Dr. Chien-Lu Ping and Dr. Gary Michaelson of the Palmer Research Center, School of Natural Resources and Agriculture Sciences, University of Alaska Fairbanks. Air temperature data are courtesy of the National Science Foundation funded (award # 1023052 ) SnowNET Project through a collaboration with Matthew Sturm (CRREL-Alaska, now at the University of Alaska Fairbanks). Toolik area precipitation data were provided by Jessie Cherry of the University of Alaska Fairbanks. Soil characterization and metal analysis (XRD, XRF and ICP-MS instrumentation) were accomplished at the University of Alaska Fairbanks-Advanced Instrumentation Laboratory with the assistance of Karen Spaleta, Maciej Sliwinski and Ken Severin. We also wish to acknowledge the editor and anonymous reviewers for their feedback, which greatly strengthened the article.

Keywords

  • Active layer
  • Arctic
  • Geochemistry
  • Permafrost
  • Surface waters
  • Trace metals

ASJC Scopus subject areas

  • Geology
  • Geochemistry and Petrology

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