Effect of permafrost thawing on trace element and carbon mobilisation

Apr 27, 2015 1 Comment by 2080 views

The Lena River (Siberia) is one of the largest global rivers draining into the Arctic Ocean. The Lena River and tributaries drain a range in lithology and topography, and the large watersheds are located in a region of continuous permafrost (ground that is permanently frozen year-round) ranging from 50 to 1500 m in thickness. The thawing of permafrost has the potential to influence the Earth’s climate feedback cycles through the release of carbon trapped within permafrost into the atmosphere – accelerating climate warming. This area is of particular interest due to potential changes in the geochemical behaviour of trace metals and organic and inorganic carbon mobilisation during permafrost thawing. There has been little research on climate changes on Plio-Pleistocene glacial-interglacial timescales, as well as the predicted future impact of climate warming.

As the climate warms, permafrost is expected to thaw to increasing depths, resulting in the development of a thicker top layer of soil that is subject to annual thawing and freezing (known as the active layer), and subsequent thermocast development (thawing of permafrost resulting in surface subsidence) and talik formation (localised unfrozen areas in a permafrost region, often located around thermocasts). This is expected to result in the exposure of more readily weathered rocks, promote greater water/rock interaction and increase river runoff, which can dramatically alter the freshwater input and trace metal and carbon fluxes into the Arctic Ocean.

As part of the MetTrans project, two previous field expeditions in the 2012/13 summers were conducted. Approximately 80 water and suspended load samples were collected along the main Lena River channel, and smaller Viliui and Aldan tributaries from the Central Siberian Plateau, Lena-Amangski inter-river area, and adjacent to the Verkhoyansk Mountain Range.

In May 2015, an expedition to sample the Lena River during the spring flood will be undertaken by Mel Murphy (University of Oxford), Don Porcelli (University of Oxford), Catherine Hirst (Swedish Museum of Natural History) and Per Andersson (Swedish Museum of Natural History). Significant mobilisation of trace elements and carbon is expected during the high discharge freshet as snow melt waters percolate the organic-rich permafrost active layer.

This research will improve our understanding of how long-term, large-scale influences of permafrost degradation within the Lena River drainage area are affecting trace element mobility and organic carbon mobilisation, and help to understand the ongoing consequences of Arctic climate warming.


About the author: Melissa Murphy is an Marie Curie Fellow from the MetTrans Initial Training Network based on the Department of Earth Sciences of the University of Oxford.

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One Response to “Effect of permafrost thawing on trace element and carbon mobilisation”

  1. Mel Murphy says:

    If anyone wants to follow us on our adventures


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