CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Tracingsilicate weathering processes in the permafrost-dominated Lena River watershedusing lithium isotopes
University of Oxford.
University of Oxford.
University College London.
Swedish Museum of Natural History, Department of Geology.
Show others and affiliations
2019 (English)In: Geochimica et Cosmochimica Acta, ISSN 0016-7037, E-ISSN 1872-9533, Vol. 245, p. 154-171Article in journal (Refereed) Published
Abstract [en]

Increasing global temperatures are causing widespread changes in the Arctic, including permafrost thawing and altered freshwater inputs and trace metal and carbon fluxes into the ocean and atmosphere. Changes in the permafrost active layer thickness can affect subsurface water flow paths and water-rock interaction times, and hence weathering processes. Riverine lithium isotope ratios (reported as δ7Li) are tracers of silicate weathering that are unaffected by biological uptake, redox, carbonate weathering and primary lithology. Here we use Li isotopes to examine silicate weathering processes in one of the largest Russian Arctic rivers: the Lena River in eastern Siberia. The Lena River watershed is a large multi-lithological catchment, underlain by continuous permafrost. An extensive dataset of dissolved Li isotopic compositions of waters from the Lena River main channel, two main tributaries (the Aldan and Viliui Rivers) and a range of smaller sub tributaries are presented from the post-spring flood/early-summer period at the onset of active layer development and enhanced water-rock interactions. The Lena River main channel (average δ7Lidiss ~19‰) has a slightly lower isotopic composition than the mean global average of 23‰ (Huh

et al., 1998a). The greatest range of [Li] and δ7Lidiss are observed in catchments draining the south facing slopes of the Verkhoyansk Mountain Range. South-facing slopes in high-latitude, permafrost dominated regions are typically characterised by increased summer insolation and higher daytime temperatures relative to other slope aspects. The increased solar radiation on south-facing catchments promotes repeated freeze-thaw cycles, and contributes to more rapid melting of snow cover, warmer soils, and increased active layer thaw depths. The greater variability in δ7Li and [Li] in the south-facing rivers likely reflect the greater infiltration of melt water and enhanced water rock interactions within the active layer. A similar magnitude of isotopic fractionation is observed between the low-lying regions of the Central Siberian Plateau (and catchments draining into the Viliui River), and catchments draining the Verkhoyansk Mountain Range into the Aldan River. This is in contrast to global rivers in non permafrost terrains that drain high elevations or areas of rapid uplift, where high degrees of physical erosion promote dissolution of freshly exposed primary rock typically yielding low δ7Lidiss, and low lying regions exhibit high riverine δ7Li values resulting from greater water-rock interaction and formation of secondary mineral that fractionates Li isotopes. Overall, the range of Li concentrations and δ7Lidiss observed within the Lena River catchment are comparable to global rivers located in temperate and tropical regions. This suggests that cryogenic weathering features specific to permafrost regions (such as the continual exposure of fresh primary minerals due to seasonal freeze-thaw cycles, frost shattering and salt weathering), and climate (temperature and runoff), are not a dominant control on δ7Li variations. Despite vastly different climatic and weathering regimes, the same range of riverine δ7Li values globally suggests that the same processes govern Li geochemistry – that is, the balance between primary silicate mineral dissolution and the formation (or exchange with) secondary minerals. This has implications for the use of δ7Li as a palaeo weathering tracer for interpreting changes in past weathering regimes.

Place, publisher, year, edition, pages
Saunders Elsevier, 2019. Vol. 245, p. 154-171
Keywords [en]
Li isotopes, Lena river, Permafrost, Weathering
National Category
Geochemistry
Research subject
The changing Earth
Identifiers
URN: urn:nbn:se:nrm:diva-3097DOI: 10.1016/j.gca.2018.10.024OAI: oai:DiVA.org:nrm-3097DiVA, id: diva2:1270311
Funder
Swedish Research Council, 621-2010-3917Swedish Polar Research Secretariat, 2011-165EU, FP7, Seventh Framework Programme, 290336Available from: 2018-12-12 Created: 2018-12-12 Last updated: 2018-12-13Bibliographically approved

Open Access in DiVA

fulltext(3971 kB)11 downloads
File information
File name FULLTEXT01.pdfFile size 3971 kBChecksum SHA-512
eefd8961423d43628e5c9f5c7ea4117ea9c1ceb0f3801d024a7713ba34f0fe98484790ba14236c57823750d0fee3637114547f6808d555ee09b9d189314486f7
Type fulltextMimetype application/pdf

Other links

Publisher's full text

Search in DiVA

By author/editor
Andersson, Per
By organisation
Department of GeologyResearch Division
In the same journal
Geochimica et Cosmochimica Acta
Geochemistry

Search outside of DiVA

GoogleGoogle Scholar
Total: 11 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

doi
urn-nbn

Altmetric score

doi
urn-nbn
Total: 28 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf