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Woods Hole Oceanographic Institution

Valier Galy

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Publications
»C residence time in the Ganges-Brahmaputra system - Nature Geoscience 2011
»Chemical composition of Ganges-Brahmaputra River sediments - JGR 2011
»Plant biomarkers in Ganges-Brahmaputra sediments - EPSL 2011
»Petrogenic carbon in the Amazon basin - Geology 2010
»Stable erosion regime in Himalaya - EPSL 2010
»Geological stabilization of C in the crust - Science 2008
»Paleovegetation LGM to present - QSR 2008
»Loading and fate of particulate organic carbon - GCA 2008
»Efficient organic carbon burial in the Bengal fan - Nature 2007
»Determination of TOC and 13C/12C - GGR 2007
»PhD Thesis


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Valier Galy, Christian France-Lanord, Olivier Beyssac, Pierre Faure, Hermann Kudrass & Fabien Palhol , Efficient organic carbon burial in the Bengal fan sustained by the Himalayan erosional system , Nature, 2007

Continental erosion controls atmospheric carbon dioxide levels on geological timescales through silicate weathering, riverine transport and subsequent burial of organic carbon in oceanic sediments. The efficiency of organic carbon deposition in sedimentary basins is however limited by the organic carbon load capacity of the sediments and organic carbon oxidation in continental margins. Previous studies have suggested that about 70 per cent of riverine organic carbon is returned to the atmosphere in the Amazon basin. Here we present a comprehensive organic carbon budget for the Himalayan erosional system, including source rocks, river sediments and marine sediments buried in the Bengal fan. We show that organic carbon export is controlled by sediment properties, and that oxidative loss is negligible during transport and deposition to the ocean. Our results indicate that 70 to 85 per cent of the organic carbon is recent organic matter captured during transport, which serves as a net sink for atmospheric carbon dioxide. The amount of organic carbon deposited in the Bengal basin represents about 10 to 20 per cent of the total terrestrial organic carbon buried in oceanic sediments. High erosion rates in the Himalayas generate high sedimentation rates and low oxygen availability in the Bay of Bengal that sustain the observed extreme organic carbon burial efficiency. Active orogenic systems generate enhanced physical erosion and the resulting organic carbon burial buffers atmospheric carbon dioxide levels, thereby exerting a negative feedback on climate over geological timescales.

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