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Molecular Tracing of Riverine Soil Organic Matter From the Central Himalaya
Author(s) -
Märki L.,
Lupker M.,
Gajurel A. P.,
Gies H.,
Haghipour N.,
Gallen S.,
FranceLanord C.,
Lavé J.,
Eglinton T.
Publication year - 2020
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2020gl087403
Subject(s) - soil water , organic matter , total organic carbon , soil organic matter , environmental science , environmental chemistry , soil carbon , geology , hydrology (agriculture) , soil science , chemistry , geotechnical engineering , organic chemistry
The isomer distribution of branched glycerol dialkyl glycerol tetraethers (brGDGTs) in soils has been shown to correlate to the local mean annual temperature. Here, we explore the use of brGDGT distributions as proxy for the elevation at which soil organic carbon is preferentially mobilized in the Central Himalaya. Soil brGDGT distributions collected along an altitudinal profile, spanning elevations from 200 to 4,450 m asl, are linearly correlated to elevation. We use this calibration to trace the provenance of soil organic matter in suspended sediments of rivers draining the Himalaya. BrGDGT distributions of fluvial sediments reflect the mean elevation of the soil cover in most catchments. Inverse modeling of the brGDGT data set suggests similar relative contribution to soil organic carbon mobilization from different land covers within a factor 2. We conclude that riverine soil organic carbon export in the Himalaya mostly occurs pervasively and is at the catchment scale insensitive to anthropogenic perturbations.