Publication Date:
2022-05-26
Description:
Author Posting. © Nature Publishing Group, 2007. This is the author's version of the work. It is posted here by permission of Nature Publishing Group for personal use, not for redistribution. The definitive version was published in Nature 450 (2007): 407-410, doi:10.1038/nature06273.
Description:
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. At the global scale, previous studies have
suggested that about 70 per cent of riverine organic carbon is returned to the
atmosphere, such as 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.
Repository Name:
Woods Hole Open Access Server
Type:
Preprint
Format:
application/pdf
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