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Riverine particulate organic carbon from an active mountain belt: Importance of landslides
Author(s) -
Hilton Robert G.,
Galy Albert,
Hovius Niels
Publication year - 2008
Publication title -
global biogeochemical cycles
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.512
H-Index - 187
eISSN - 1944-9224
pISSN - 0886-6236
DOI - 10.1029/2006gb002905
Subject(s) - total organic carbon , geology , bedrock , landslide , sediment , alluvium , hydrology (agriculture) , particulates , isotopes of carbon , alluvial fan , geochemistry , geomorphology , sedimentary rock , environmental chemistry , ecology , chemistry , geotechnical engineering , biology
We investigate the routing and transfer of particulate organic carbon (POC) from the western Southern Alps, New Zealand, using organic carbon (C org ) and nitrogen (N org ) concentrations and stable carbon isotopes ( δ 13 C org ). 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 CO 2 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 CO 2 .