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Oxidation of petrogenic organic carbon in the Amazon floodplain as a source of atmospheric CO (sub 2)

Julien Bouchez, Olivier Beyssac, Valier Galy, Jerome Gaillardet, Christian France-Lanord, Laurence Maurice and Patricia Moreira-Turcq
Oxidation of petrogenic organic carbon in the Amazon floodplain as a source of atmospheric CO (sub 2)
Geology (Boulder) (March 2010) 38 (3): 255-258

Abstract

The two long-term sources of atmospheric carbon are CO (sub 2) degassing from metamorphic and volcanic activity, and oxidation of organic carbon (OC) contained in sedimentary rocks, or petrogenic organic carbon (OC (sub petro) ). The latter flux is still poorly constrained. In this study, we report particulate organic carbon content and (super 14) C activity measurements in Amazon River sediments, which allow for estimates of the OC (sub petro) content of these sediments. A large decrease of OC (sub petro) content in riverine sediments is observed from the outlet of the Andes to the mouth of the large tributaries. This loss reveals oxidation of OC (sub petro) during transfer of sediments in the floodplain, and results in an escape of approximately 0.25 Mt C/yr to the atmosphere, which is on the same order of magnitude as the CO (sub 2) consumption by silicate weathering in the same area. Raman microspectroscopy investigations show that graphite is the most stable phase with respect to this oxidation process. These results emphasize the significance of OC (sub petro) oxidation in large river floodplains in the global carbon cycle.


ISSN: 0091-7613
EISSN: 1943-2682
Coden: GLGYBA
Serial Title: Geology (Boulder)
Serial Volume: 38
Serial Issue: 3
Title: Oxidation of petrogenic organic carbon in the Amazon floodplain as a source of atmospheric CO (sub 2)
Affiliation: Institut de Physique du Globe de Paris, Paris, France
Pages: 255-258
Published: 201003
Text Language: English
Publisher: Geological Society of America (GSA), Boulder, CO, United States
References: 32
Accession Number: 2010-030933
Categories: Geochemistry of rocks, soils, and sedimentsHydrogeology
Document Type: Serial
Bibliographic Level: Analytic
Annotation: Includes appendix
Illustration Description: illus. incl. 1 table, sketch map
S20°00'00" - N05°00'00", W70°00'00" - W50°00'00"
Secondary Affiliation: Ecole Normale Superieure, FRA, FranceWoods Hole Oceanographic Institution, USA, United StatesCentre de Recherches Petrographiques et Geochimiques, FRA, FranceInstitut de Recherche pour le Developpement, FRA, France
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 201018
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