Riverine particulate organic carbon from an active mountain belt: Importance of landslides

Hilton, R. G. and Galy, A. and Hovius, N. (2008) Riverine particulate organic carbon from an active mountain belt: Importance of landslides. Global Biogeochemical Cycles, 22. GB1017. DOI https://doi.org/10.1029/2006GB002905

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Official URL: http://dx.doi.org/10.1029/2006GB002905


We investigate the routing and transfer of particulate organic carbon (POC) from the western Southern Alps, New Zealand, using organic carbon (Corg) and nitrogen (Norg) concentrations and stable carbon isotopes (δ 13Corg). In this active mountain belt, sediment discharge is dominated by landslide-derived material. Landsliding acts to homogenize the geochemically diverse hillslope POC, mixing POC from the standing biomass and soil with the fossil POC from bedrock. As a result, the POC in river sediment at the mountain front is a binary mixture of fossil and nonfossil carbon sourced from many landslide deposits. We calculate that nonfossil biogenic POC makes up 63 ± 7% of the total POC in the suspended load of rivers draining the western Southern Alps. The erosional flux of biogenic POC from these catchments represents a transfer of 39 tC km−2 a−1 of atmospheric CO2 averaged over the west flank of the mountain belt. If more than 10% of this POC is preserved in sediments on geological timescales, then this process is the most significant way in which the Southern Alps and similar, tectonically active mountain belts with restricted alluvial aprons consume atmospheric CO2.

Item Type: Article
Uncontrolled Keywords: 2007 AREP IA55
Subjects: 01 - Climate Change and Earth-Ocean Atmosphere Systems
02 - Geodynamics, Geophysics and Tectonics
Divisions: 02 - Geodynamics, Geophysics and Tectonics
Journal or Publication Title: Global Biogeochemical Cycles
Volume: 22
Page Range: GB1017
Identification Number: https://doi.org/10.1029/2006GB002905
Depositing User: Sarah Humbert
Date Deposited: 16 Feb 2009 13:02
Last Modified: 23 Jul 2013 10:07
URI: http://eprints.esc.cam.ac.uk/id/eprint/380

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