Seasonal hydrology and permafrost disturbance impacts on dissolved organic matter composition in High Arctic headwater catchments 1

• Published in: Arctic Science
• Main Authors: Fouché, Julien, Lafrenière, M., J, Rutherford, K., Lamoureux, S.
• Other Authors: Laboratoire d'étude des Interactions Sol - Agrosystème - Hydrosystème (UMR LISAH), Institut de Recherche pour le Développement (IRD)-Institut National de la Recherche Agronomique (INRA)-Centre international d'études supérieures en sciences agronomiques (Montpellier SupAgro)-Institut national d’études supérieures agronomiques de Montpellier (Montpellier SupAgro), Queen's University Kingston, Canada
• Format: Article in Journal/Newspaper
• Language: French
• Published: HAL CCSD 2017
• Subjects: active layer detachments; dissolved organic matter; fluorescence; High Arctic; parallel factor analysis (PARAFAC); décollements de la couche active; matière organique dissoute; Haut-Arctique; analyse de facteurs parallèles (« PARAFAC »); [SDU.STU.HY]Sciences of the Universe [physics]/Earth Sciences/Hydrology; [SDU.STU.GL]Sciences of the Universe [physics]/Earth Sciences/Glaciology; [SDE.MCG]Environmental Sciences/Global Changes; Arctic; Canada; Cape Bounty; Arctique*; Climate change; permafrost; Melville Island; pergélisol
• Online Access: https://hal.science/hal-02438747; https://hal.science/hal-02438747/document; https://hal.science/hal-02438747/file/Fouch%C3%A9%20et%20al.,%202017.pdf; https://doi.org/10.1139/as-2016-0031

International audience Arctic landscapes are experiencing intense warming and modification of precipitation regimes with climate change. Permafrost disturbances and climate change impacts on hydrology of Arctic watersheds are likely to modify the quantity and composition of exported dissolved organic matter (DOM). In July 2007, intense rainfall and active layer thickening caused widespread active layer detachments at Cape Bounty, Melville Island (Canada). This study investigates the impacts of seasonal hydrology and permafrost disturbance on DOM composition exported from High Arctic headwater catchments. In 2012, streams were sampled from three disturbed catchments and one undisturbed catchment. The composition of DOM was characterized using absorbance and fluorescence spectroscopy. DOM was mostly exported during the spring freshet. Throughout this period, the undisturbed catchment exported humified DOM with high humic-like fluorescence that likely originated from runoff through shallow organic rich soil. In contrast, DOM exported from disturbed catchments was fresher, less humified with a high proportion of low molecular weight humic acid. We demonstrate that disturbed catchments delivered likely more labile DOM derived from either thawed permafrost or enhanced microbial activity. If this labile DOM comes from an ancient pool, as indicated by other studies at this site, disturbances may strengthen the permafrost carbon feedback on climate change. Avec le changement climatique, les paysages arctiques connaissent un réchauffe-ment intense et une modification des régimes de précipitation. Les impacts des perturbations du pergélisol et du changement climatique sur l'hydrologie des bassins hydrographiques arc-tiques vont probablement modifier la quantité et la composition de matière organique dis-soute (MOD) exportée. En juillet 2007, des averses intenses et l'épaississement de la couche active ont causé des décollements généralisés de la couche active à Cape Bounty, île Melville (Canada). Cette étude examine ...