Li and U Isotopes as a Potential Tool for Monitoring Active Layer Deepening in Permafrost Dominated Catchments
Permafrost in the Arctic is decreasing in extent and the depth of the seasonally thawed layer, the active layer, is increasing. Increased exposure to water is increasing fluxes of organic and inorganic solutes with potential impacts for the global carbon cycle and downstream ecosystems. Understandin...
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ftunivcam:oai:www.repository.cam.ac.uk:1810/283061 2024-01-14T10:04:34+01:00 Li and U Isotopes as a Potential Tool for Monitoring Active Layer Deepening in Permafrost Dominated Catchments Hindshaw, RS Aciego, SM Tipper, ET 2018 application/pdf https://www.repository.cam.ac.uk/handle/1810/283061 https://doi.org/10.17863/CAM.30423 eng eng Frontiers Media SA http://dx.doi.org/10.3389/feart.2018.00102 Frontiers in Earth Science https://www.repository.cam.ac.uk/handle/1810/283061 doi:10.17863/CAM.30423 Attribution 4.0 International https://creativecommons.org/licenses/by/4.0/ permafrost Arctic lithium isotopes uranium isotopes geochemistry weathering active-layer glacier Article 2018 ftunivcam https://doi.org/10.17863/CAM.30423 2023-12-21T23:22:04Z Permafrost in the Arctic is decreasing in extent and the depth of the seasonally thawed layer, the active layer, is increasing. Increased exposure to water is increasing fluxes of organic and inorganic solutes with potential impacts for the global carbon cycle and downstream ecosystems. Understanding the relationship between solute release and active layer depth will be critical for modeling environmental impact, especially in inaccessible regions where there is a lack of data. In this study, we focus on the potential for the isotopes of lithium (Li) and uranium (U) to track active layer extent in two permafrost-dominated catchments in Svalbard: one glaciated and one unglaciated. These isotope systems can be measured to a much higher precision than concentration measurements and act as sensitive tracers of environmental change. The extent of Li isotope fractionation provides information on the balance between dissolution of primary phases and formation of secondary phases, such as clay minerals and oxides. The U activity ratio provides information on water-rock interaction times and physical properties. We observe contrasting behavior between the two catchments. The highest U activity ratios and Li isotope values (those most distinct from bedrock) are observed in summer in the unglaciated catchment, when the active layer depth is expected to be at its maximum extent, whereas negligible seasonal variation and the lowest values are observed in the glaciated catchment. We therefore propose that the extent of solute acquisition is directly linked to the active layer depth, which is restricted in the glaciated catchment due to a layer of “dead ice” underneath the glacial outwash plain, and could therefore provide a valuable tool to assess changes in active layer depth at catchment scales. This project was funded by a Swiss National Science Foundation fellowship for prospective researchers (PBEZP2-137335), a Marie Curie Intra-European Fellowship (PIEF-GA-2012-331501), and NERC Standard Grant NE/M001865/1. Fieldwork ... Article in Journal/Newspaper Arctic glacier Ice permafrost Svalbard Apollo - University of Cambridge Repository Arctic Svalbard |
institution |
Open Polar |
collection |
Apollo - University of Cambridge Repository |
op_collection_id |
ftunivcam |
language |
English |
topic |
permafrost Arctic lithium isotopes uranium isotopes geochemistry weathering active-layer glacier |
spellingShingle |
permafrost Arctic lithium isotopes uranium isotopes geochemistry weathering active-layer glacier Hindshaw, RS Aciego, SM Tipper, ET Li and U Isotopes as a Potential Tool for Monitoring Active Layer Deepening in Permafrost Dominated Catchments |
topic_facet |
permafrost Arctic lithium isotopes uranium isotopes geochemistry weathering active-layer glacier |
description |
Permafrost in the Arctic is decreasing in extent and the depth of the seasonally thawed layer, the active layer, is increasing. Increased exposure to water is increasing fluxes of organic and inorganic solutes with potential impacts for the global carbon cycle and downstream ecosystems. Understanding the relationship between solute release and active layer depth will be critical for modeling environmental impact, especially in inaccessible regions where there is a lack of data. In this study, we focus on the potential for the isotopes of lithium (Li) and uranium (U) to track active layer extent in two permafrost-dominated catchments in Svalbard: one glaciated and one unglaciated. These isotope systems can be measured to a much higher precision than concentration measurements and act as sensitive tracers of environmental change. The extent of Li isotope fractionation provides information on the balance between dissolution of primary phases and formation of secondary phases, such as clay minerals and oxides. The U activity ratio provides information on water-rock interaction times and physical properties. We observe contrasting behavior between the two catchments. The highest U activity ratios and Li isotope values (those most distinct from bedrock) are observed in summer in the unglaciated catchment, when the active layer depth is expected to be at its maximum extent, whereas negligible seasonal variation and the lowest values are observed in the glaciated catchment. We therefore propose that the extent of solute acquisition is directly linked to the active layer depth, which is restricted in the glaciated catchment due to a layer of “dead ice” underneath the glacial outwash plain, and could therefore provide a valuable tool to assess changes in active layer depth at catchment scales. This project was funded by a Swiss National Science Foundation fellowship for prospective researchers (PBEZP2-137335), a Marie Curie Intra-European Fellowship (PIEF-GA-2012-331501), and NERC Standard Grant NE/M001865/1. Fieldwork ... |
format |
Article in Journal/Newspaper |
author |
Hindshaw, RS Aciego, SM Tipper, ET |
author_facet |
Hindshaw, RS Aciego, SM Tipper, ET |
author_sort |
Hindshaw, RS |
title |
Li and U Isotopes as a Potential Tool for Monitoring Active Layer Deepening in Permafrost Dominated Catchments |
title_short |
Li and U Isotopes as a Potential Tool for Monitoring Active Layer Deepening in Permafrost Dominated Catchments |
title_full |
Li and U Isotopes as a Potential Tool for Monitoring Active Layer Deepening in Permafrost Dominated Catchments |
title_fullStr |
Li and U Isotopes as a Potential Tool for Monitoring Active Layer Deepening in Permafrost Dominated Catchments |
title_full_unstemmed |
Li and U Isotopes as a Potential Tool for Monitoring Active Layer Deepening in Permafrost Dominated Catchments |
title_sort |
li and u isotopes as a potential tool for monitoring active layer deepening in permafrost dominated catchments |
publisher |
Frontiers Media SA |
publishDate |
2018 |
url |
https://www.repository.cam.ac.uk/handle/1810/283061 https://doi.org/10.17863/CAM.30423 |
geographic |
Arctic Svalbard |
geographic_facet |
Arctic Svalbard |
genre |
Arctic glacier Ice permafrost Svalbard |
genre_facet |
Arctic glacier Ice permafrost Svalbard |
op_relation |
https://www.repository.cam.ac.uk/handle/1810/283061 doi:10.17863/CAM.30423 |
op_rights |
Attribution 4.0 International https://creativecommons.org/licenses/by/4.0/ |
op_doi |
https://doi.org/10.17863/CAM.30423 |
_version_ |
1788059069862379520 |