Sediment dynamics; Himalaya; Long-term carbon cycle; Erosion processes; Organic carbon
Märki L., Lupker M., Gajurel A. P., Gies H., Haghipour N., Gallen S., France‐Lanord C., Lavé J., Eglinton T. (2020), Molecular Tracing of Riverine Soil Organic Matter From the Central Himalaya, in Geophysical Research Letters
, 47(16), 1.
MärkiLena, LupkerMaarten, France-LanordChristian, LaveJerome, GallenSean, GajurelAnanta, HaghipourNegar, Leuenberger-WestFanny, EglintonTimothy, An unshakable carbon budget for the Himalaya, in Nature Geoscience
Understanding how climate, tectonics and earth surface processes interact is amongst the most challenging issues in earth surface sciences. Over geological time-scales, atmospheric carbon dioxide levels and hence the global climate, are controlled by the intensity of chemical weathering reactions of silicate rocks and by the mobilization of organic carbon followed by its burial on continental margins. These processes are carbon sinks that balance the continuous input of crustal CO2 and hence stabilize the Earth’s climate. The role of the organic carbon cycle in the global evolution of climate has, so far, received less attention than its inorganic counterpart (silicate weathering). The controls on the mobilization and export of organic material are not well understood or quantified and the relative importance of both the organic and inorganic sinks and their sensitivity with respect to changes in tectonic or climatic forcing is largely unknown. The aim of this project is to quantify to what extent climate, topography and erosion processes control the availability, mobilization and transfer of organic carbon to the river network in mountainous basins. To answer these questions, we propose a longitudinal study of organic carbon cycling in the Narayani River (central Nepal) that covers a large gradient in tectonic and climatic conditions. The research plan is subdivided in 3 inter-related tasks:1)Build an inventory of organic carbon stores in different sub-catchments of the Narayani River basin. An extensive sample-set collected in the field will be used to geochemically characterize the main organic carbon stores across climatic and tectonic gradients (vegetation, soils, bedrock etc.). This will allow us to address controls on organic carbon stores at the landscape scale in terms of organic carbon quality and quantity.2)Asses the fluxes and geochemical signatures of organic carbon exported by the river systems based on time-series sampling approaches. This task will allow us to characterize the controls and “efficiency” of riverine carbon export under different tectonic and climatic conditions and will allow us to derive a complete budget of organic carbon cycling3)Evaluate the possible effect of the Mw 7.8, April 2015 Gorkha earthquake on the cycling of organic matter in active an active setting such as central Nepal.The major strength of this proposal lies in the use of a wide range of approaches that will allow us to develop quantitative constraints on the carbon cycling and export in mountainous catchments and asses how sensitive these are to extreme events. It will also yield new insights into the role of continental erosion in regulating the global carbon cycle in an important, and globally significant area: the Himalayan orogen. The project is designed for one PhD student that will essentially be involved in the fieldwork and organic geochemical investigations.