TY - JOUR
T1 - Strontium isotopes trace the dissolution and precipitation of mineral organic carbon interactions in thawing permafrost
AU - Monhonval, Arthur
AU - Hirst, Catherine
AU - Strauss, Jens
AU - Schuur, Edward A.G.
AU - Opfergelt, Sophie
N1 - Funding Information:
We thank Elisabeth Mauclet, Simon Malvaux and Justin Ledman for their help on the field and Emily Stevenson for her help with the Sr isotope methodology, Hélène Dailly and the Mineral and Organic Chemical Analysis (MOCA) platform from UCLouvain for the chemical and isotopic analysis, Aubry Vandeuren and Benoît Pereira for their expertise on portable X-ray Fluorescence, and Sébastien François and the technical unit from Earth and Life Institute environment (ELIE) for their help with the steel pipe sampling device construction. We acknowledge the associate editor Alberto Agnelli and two anonymous reviewers for their constructive comments. We thank Guido Grosse and Lutz Schirrmeister for their expertise on the site of Duvanny Yar, a work embedded into the Action Group “The Yedoma Region” funded by the International Permafrost Association, and ECOSS in Flagstaff for their expertise on Eight Mile Lake study site. This work was supported by the European Union’s Horizon 2020 research and innovation program [grant agreement No. 714617 ] to SO, and SO acknowledges funding from the Fund for Scientific Research FNRS in Belgium [ FC69480 ].
Funding Information:
We thank Elisabeth Mauclet, Simon Malvaux and Justin Ledman for their help on the field and Emily Stevenson for her help with the Sr isotope methodology, Hélène Dailly and the Mineral and Organic Chemical Analysis (MOCA) platform from UCLouvain for the chemical and isotopic analysis, Aubry Vandeuren and Benoît Pereira for their expertise on portable X-ray Fluorescence, and Sébastien François and the technical unit from Earth and Life Institute environment (ELIE) for their help with the steel pipe sampling device construction. We acknowledge the associate editor Alberto Agnelli and two anonymous reviewers for their constructive comments. We thank Guido Grosse and Lutz Schirrmeister for their expertise on the site of Duvanny Yar, a work embedded into the Action Group “The Yedoma Region” funded by the International Permafrost Association, and ECOSS in Flagstaff for their expertise on Eight Mile Lake study site. This work was supported by the European Union's Horizon 2020 research and innovation program [grant agreement No. 714617] to SO, and SO acknowledges funding from the Fund for Scientific Research FNRS in Belgium [FC69480].
Publisher Copyright:
© 2023 The Author(s)
PY - 2023/5
Y1 - 2023/5
N2 - Interactions between minerals and organic carbon (OC) in soils are key to stabilize OC and mitigate greenhouse gas emissions upon permafrost thaw. However, changes in soil water pathways upon permafrost thaw are likely to affect the stability of mineral OC interactions by inducing their dissolution and precipitation. This study aims to assess and quantify how mineral OC interactions are affected by dissolution and precipitation in thawed relative to unthawed layers. We hypothesize that a change in the radiogenic strontium (Sr) isotopic ratio (87Sr/86Sr) involved in mineral OC interactions upon changing water saturation conditions implies a destabilization of the mineral OC interaction. We quantified mineral OC interactions using selective extractions in soils facing gradual thaw (Eight Mile Lake, AK, USA) and in sediments with a thawing history of abrupt thaw (Duvanny Yar, Russia), and we measured the 87Sr/86Sr ratio of the selective extracts targeting the Sr associated to mineral OC interactions. Firstly, for water saturated layers with a higher proportion of mineral OC interactions, we found a difference in the 87Sr/86Sr ratio relative to the surrounding layers, and this supports the preservation of a Sr “stable” pool in these mineral OC interactions. We estimated that a portion of these mineral OC interactions have remained undissociated since their formation (between 4% and 64% by Sr isotope mass balance). Secondly, we found no difference in 87Sr/86Sr ratio between layers accumulating Fe oxides at redox interfaces regularly affected by water table changes (or upon thermokarst processes) relative to surrounding layers. This supports the dominance of a Sr “labile” pool inherited from processes of dissolution and precipitation of the mineral OC interactions. Thirdly, our estimations based on a Sr isotope mass balance support that, as a consequence of permafrost thaw, a larger proportion of Sr from primary mineral weathering (>80%) controls the Sr in mineral OC interactions in the saturated zone of deeply thawed soils relative to poorly thawed soils (∼50%). In conclusion, we found that the radiogenic Sr isotope method, applied for the first time in this context, is promising to trace dissolution-precipitation processes of mineral OC interaction in thawing permafrost.
AB - Interactions between minerals and organic carbon (OC) in soils are key to stabilize OC and mitigate greenhouse gas emissions upon permafrost thaw. However, changes in soil water pathways upon permafrost thaw are likely to affect the stability of mineral OC interactions by inducing their dissolution and precipitation. This study aims to assess and quantify how mineral OC interactions are affected by dissolution and precipitation in thawed relative to unthawed layers. We hypothesize that a change in the radiogenic strontium (Sr) isotopic ratio (87Sr/86Sr) involved in mineral OC interactions upon changing water saturation conditions implies a destabilization of the mineral OC interaction. We quantified mineral OC interactions using selective extractions in soils facing gradual thaw (Eight Mile Lake, AK, USA) and in sediments with a thawing history of abrupt thaw (Duvanny Yar, Russia), and we measured the 87Sr/86Sr ratio of the selective extracts targeting the Sr associated to mineral OC interactions. Firstly, for water saturated layers with a higher proportion of mineral OC interactions, we found a difference in the 87Sr/86Sr ratio relative to the surrounding layers, and this supports the preservation of a Sr “stable” pool in these mineral OC interactions. We estimated that a portion of these mineral OC interactions have remained undissociated since their formation (between 4% and 64% by Sr isotope mass balance). Secondly, we found no difference in 87Sr/86Sr ratio between layers accumulating Fe oxides at redox interfaces regularly affected by water table changes (or upon thermokarst processes) relative to surrounding layers. This supports the dominance of a Sr “labile” pool inherited from processes of dissolution and precipitation of the mineral OC interactions. Thirdly, our estimations based on a Sr isotope mass balance support that, as a consequence of permafrost thaw, a larger proportion of Sr from primary mineral weathering (>80%) controls the Sr in mineral OC interactions in the saturated zone of deeply thawed soils relative to poorly thawed soils (∼50%). In conclusion, we found that the radiogenic Sr isotope method, applied for the first time in this context, is promising to trace dissolution-precipitation processes of mineral OC interaction in thawing permafrost.
KW - Arctic
KW - Iron oxides
KW - Mineral-associated organic carbon
KW - Permafrost
KW - Strontium isotopes
KW - Thaw
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U2 - 10.1016/j.geoderma.2023.116456
DO - 10.1016/j.geoderma.2023.116456
M3 - Article
AN - SCOPUS:85151306505
SN - 0016-7061
VL - 433
JO - Geoderma
JF - Geoderma
M1 - 116456
ER -