Sustained sulfide oxidation by physical erosion processes in the Mackenzie River basin: Climatic perspectives

Research Article| November 01, 2007 Sustained sulfide oxidation by physical erosion processes in the Mackenzie River basin: Climatic perspectives Damien Calmels; Damien Calmels 1Equipe de Géochimie et Cosmochimie, Institut de Physique du Globe de Paris, Université Paris 7, Centre National de la Recherche Scientifique, 4 place Jussieu-75252 Paris cedex 05, France Search for other works by this author on: GSW Google Scholar Jérôme Gaillardet; Jérôme Gaillardet 1Equipe de Géochimie et Cosmochimie, Institut de Physique du Globe de Paris, Université Paris 7, Centre National de la Recherche Scientifique, 4 place Jussieu-75252 Paris cedex 05, France Search for other works by this author on: GSW Google Scholar Agnès Brenot; Agnès Brenot 2Centre de Recherches Pétrographiques et Géochimiques, Centre National de la Recherche Scientifique, 15 rue Notre-Dames des Pauvres-54501 Vandoeuvre-les-Nancy, France Search for other works by this author on: GSW Google Scholar Christian France-Lanord Christian France-Lanord 2Centre de Recherches Pétrographiques et Géochimiques, Centre National de la Recherche Scientifique, 15 rue Notre-Dames des Pauvres-54501 Vandoeuvre-les-Nancy, France Search for other works by this author on: GSW Google Scholar Author and Article Information Damien Calmels 1Equipe de Géochimie et Cosmochimie, Institut de Physique du Globe de Paris, Université Paris 7, Centre National de la Recherche Scientifique, 4 place Jussieu-75252 Paris cedex 05, France Jérôme Gaillardet 1Equipe de Géochimie et Cosmochimie, Institut de Physique du Globe de Paris, Université Paris 7, Centre National de la Recherche Scientifique, 4 place Jussieu-75252 Paris cedex 05, France Agnès Brenot 2Centre de Recherches Pétrographiques et Géochimiques, Centre National de la Recherche Scientifique, 15 rue Notre-Dames des Pauvres-54501 Vandoeuvre-les-Nancy, France Christian France-Lanord 2Centre de Recherches Pétrographiques et Géochimiques, Centre National de la Recherche Scientifique, 15 rue Notre-Dames des Pauvres-54501 Vandoeuvre-les-Nancy, France Publisher: Geological Society of America Received: 30 May 2007 Revision Received: 26 Jun 2007 Accepted: 27 Jun 2007 First Online: 09 Mar 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 The Geological Society of America, Inc. Geology (2007) 35 (11): 1003–1006. https://doi.org/10.1130/G24132A.1 Article history Received: 30 May 2007 Revision Received: 26 Jun 2007 Accepted: 27 Jun 2007 First Online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Damien Calmels, Jérôme Gaillardet, Agnès Brenot, Christian France-Lanord; Sustained sulfide oxidation by physical erosion processes in the Mackenzie River basin: Climatic perspectives. Geology 2007;; 35 (11): 1003–1006. doi: https://doi.org/10.1130/G24132A.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract The chemical weathering of rocks with sulfuric acid is usually not considered in reconstructions of the past evolution of the carbon cycle, although this reaction delivers cations and alkalinity to the ocean without involvement of atmospheric CO2. The contribution of sulfuric acid as a weathering agent is still poorly quantified; the identification of riverine sulfate sources is difficult. The use of δ34S and δ18O of dissolved sulfate allows us to demonstrate that most of the sulfate in surface waters of the Mackenzie River system, Canada, derives from pyrite oxidation (85% ± 5%) and not from sedimentary sulfate. The calculated flux of pyrite-derived sulfate is 0.13 × 1012 mol/yr, corresponding to 20%–27% of the estimated global budget. This result suggests that the modern global ocean delivery of sulfide-derived sulfate, and thus chemical weathering with sulfuric acid, may be significantly underestimated. A strong correlation between sulfide oxidation rates and mechanical erosion rates suggests that the exposure of fresh mineral surfaces is the rate-limiting factor of sulfide oxidation in the subbasins investigated. The chemical weathering budget of the Mackenzie River shows that more than half of the dissolved inorganic carbon discharged to the ocean is ancient sedimentary carbon from carbonate (62%) and not atmospheric carbon (38%). The subsequent carbonate precipitation in the ocean will thus release more CO2 in the atmosphere-ocean system than that consumed by continental weathering, typically on glacial-interglacial time scales. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.