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Conférence de Rose Cory sur le dégel du pergélisol

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Rose Cory, professeure à l'Université du Michigan au Département des Sciences de la Terre et de l'environnement, présentera une conférence le jeudi 14 mars 2019 à 11 h, à la salle 2422 du Centre Eau Terre Environnement de l'INRS. 

La conférence de Rose Cory s'intitule Oxidation of dissolved organic matter in arctic freshwaters by iron, sunlight and microorganisms.  

 

Bienvenue à tous ! 

 

Résumé:

The ongoing thawing of permafrost soils is the only environmental change that allows tremendous stores of organic carbon (C) to be converted into carbon dioxide (CO2) on decadal time scales, thus providing a positive and accelerating feedback to global warming.  Organic C in permafrost soils must be unfrozen, dissolved, and oxidized before it can feedback to the atmosphere as CO2.  This talk will summarize what we have learned about the oxidation of dissolved organic matter (DOM) to CO2 in the Arctic: (1) Abiotic redox reactions initiated by iron in soils or sunlight in freshwaters oxidize as much DOM to CO2 as does microbial respiration of DOM in surface waters draining permafrost soils. (2) Partial oxidation of DOM by sunlight accounts for the majority of DOM processed in arctic freshwaters. (3) Partial photo-oxidation of DOM has costs and benefits to microbes.  Costs include photochemical removal or alteration of compounds that support microbial growth.  A benefit of photo-oxidation is that it alleviates the need for key enzymes used by microbes to degrade DOM. Permafrost DOM is at least as labile as DOM draining from the active soil layer to oxidation by iron, sunlight and microbes.  High lability of permafrost DOM to oxidation combined with earlier ice-out on arctic lakes indicate that these controls on DOM oxidation will continue to be important for the fate of frozen soil carbon in a warming world. 

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