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Canadian permafrost stores large pools of ammonium and optically distinct dissolved organic matter.

https://arctichealth.org/en/permalink/ahliterature304784
Source
Nat Commun. 2020 09 09; 11(1):4500
Publication Type
Journal Article
Research Support, Non-U.S. Gov't
Date
09-09-2020
Author
J Fouché
C T Christiansen
M J Lafrenière
P Grogan
S F Lamoureux
Author Affiliation
LISAH, Univ Montpellier, INRAE, IRD, Institut Agro, 34060, Montpellier, France. julien.fouche@supagro.fr.
Source
Nat Commun. 2020 09 09; 11(1):4500
Date
09-09-2020
Language
English
Publication Type
Journal Article
Research Support, Non-U.S. Gov't
Abstract
Permafrost degradation may lead to mobilization of carbon and nutrients and enhance microbial processing rates of previously frozen organic matter. Although the pool size and chemical composition of dissolved organic matter (DOM) are fundamental determinants of the carbon cycle in Arctic watersheds, its source within the seasonally thawing active layer and the underlying permafrost remains largely uncharacterized. Here, we used 25 soil cores that extended down into the permafrost from nine sites across Arctic Canada to quantify dissolved organic carbon (DOC) and nitrogen stocks, and to characterize DOM optical properties. Organic permafrost stores 5-7 times more DOC and ammonium than the active layer and mineral permafrost. Furthermore, the permafrost layers contain substantial low molecular weight DOM with low aromaticity suggesting high biodegradability. We conclude that soil organic matter stoichiometry and cryogenic processes determine permafrost DOM chemistry, and that thawing will mobilize large amounts of labile DOC and ammonium into Arctic watersheds.
PubMed ID
32908152 View in PubMed
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Climate and permafrost effects on the chemistry and ecosystems of High Arctic Lakes.

https://arctichealth.org/en/permalink/ahliterature286487
Source
Sci Rep. 2017 Oct 16;7(1):13292
Publication Type
Article
Date
Oct-16-2017
Author
K E Roberts
S F Lamoureux
T K Kyser
D C G Muir
M J Lafrenière
D. Iqaluk
A J Pienkowski
A. Normandeau
Source
Sci Rep. 2017 Oct 16;7(1):13292
Date
Oct-16-2017
Language
English
Publication Type
Article
Abstract
Permafrost exerts an important control over hydrological processes in Arctic landscapes and lakes. Recent warming and summer precipitation has the potential to alter water availability and quality in this environment through thermal perturbation of near surface permafrost and increased mobility of previously frozen solutes to Arctic freshwaters. We present a unique thirteen-year record (2003-16) of the physiochemical properties of two High Arctic lakes and show that the concentration of major ions, especially SO4(2-), has rapidly increased up to 500% since 2008. This hydrochemical change has occurred synchronously in both lakes and ionic ratio changes in the lakes indicate that the source for the SO4(2-) is compositionally similar to terrestrial sources arising from permafrost thaw. Record summer temperatures during this period (2003-16) following over 100 years of warming and summer precipitation in this polar desert environment provide likely mechanisms for this rapid chemical change. An abrupt limnological change is also reflected in the otolith chemistry and improved relative condition of resident Arctic char (Salvelinus alpinus) and increased diatom diversity point to a positive ecosystem response during the same period.
Notes
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Cites: Science. 2009 Sep 4;325(5945):1236-919729653
PubMed ID
29038475 View in PubMed
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Differential impact of thermal and physical permafrost disturbances on High Arctic dissolved and particulate fluvial fluxes.

https://arctichealth.org/en/permalink/ahliterature305294
Source
Sci Rep. 2020 07 16; 10(1):11836
Publication Type
Journal Article
Research Support, Non-U.S. Gov't
Date
07-16-2020
Author
C R Beel
S F Lamoureux
J F Orwin
M A Pope
M J Lafrenière
N A Scott
Author Affiliation
Department of Geography and Planning, Queen's University, Kingston, ON, K7L 3N6, Canada. cbeel@wlu.ca.
Source
Sci Rep. 2020 07 16; 10(1):11836
Date
07-16-2020
Language
English
Publication Type
Journal Article
Research Support, Non-U.S. Gov't
Abstract
Climate warming and changing precipitation patterns have thermally (active layer deepening) and physically (permafrost-thaw related mass movements) disturbed permafrost-underlain watersheds across much of the Arctic, increasing the transfer of dissolved and particulate material from terrestrial to aquatic ecosystems. We examined the multiyear (2006-2017) impact of thermal and physical permafrost disturbances on all of the major components of fluvial flux. Thermal disturbances increased the flux of dissolved organic carbon (DOC), but localized physical disturbances decreased multiyear DOC flux. Physical disturbances increased major ion and suspended sediment flux, which remained elevated a decade after disturbance, and changed carbon export from a DOC to a particulate organic carbon (POC) dominated system. As the magnitude and frequency of physical permafrost disturbance intensifies in response to Arctic climate change, disturbances will become an increasingly important mechanism to deliver POC from terrestrial to aquatic ecosystems. Although nival runoff remained the primary hydrological driver, the importance of pluvial runoff as driver of fluvial flux increased following both thermal and physical permafrost disturbance. We conclude the transition from a nival-dominated fluvial regime to a regime where rainfall runoff is proportionately more important will be a likely tipping point to accelerated High Arctic change.
PubMed ID
32678255 View in PubMed
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Emerging dominance of summer rainfall driving High Arctic terrestrial-aquatic connectivity.

https://arctichealth.org/en/permalink/ahliterature306497
Source
Nat Commun. 2021 03 04; 12(1):1448
Publication Type
Journal Article
Research Support, Non-U.S. Gov't
Date
03-04-2021
Author
C R Beel
J K Heslop
J F Orwin
M A Pope
A J Schevers
J K Y Hung
M J Lafrenière
S F Lamoureux
Author Affiliation
Department of Geography and Planning, Queen's University, Kingston, ON, Canada. Casey_Beel@gov.nt.ca.
Source
Nat Commun. 2021 03 04; 12(1):1448
Date
03-04-2021
Language
English
Publication Type
Journal Article
Research Support, Non-U.S. Gov't
Abstract
Hydrological transformations induced by climate warming are causing Arctic annual fluvial energy to shift from skewed (snowmelt-dominated) to multimodal (snowmelt- and rainfall-dominated) distributions. We integrated decade-long hydrometeorological and biogeochemical data from the High Arctic to show that shifts in the timing and magnitude of annual discharge patterns and stream power budgets are causing Arctic material transfer regimes to undergo fundamental changes. Increased late summer rainfall enhanced terrestrial-aquatic connectivity for dissolved and particulate material fluxes. Permafrost disturbances (
PubMed ID
33664252 View in PubMed
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