Leaf wax biomarkers in transit record river catchment composition
West, A. Joshua
Feakins, Sarah J.
MetadataShow full item record
Rivers carry organic molecules derived from terrestrial vegetation to sedimentary deposits in lakes and oceans, storing information about past climate and erosion, as well as representing a component of the carbon cycle. It is anticipated that sourcing of organic matter may not be uniform across catchments with substantial environmental variability in topography, vegetation zones, and climate. Here we analyze plant leaf wax biomarkers in transit in the Madre de Dios River (Peru), which drains a forested catchment across 4.5 km of elevation from the tropical montane forests of the Andes down into the rainforests of Amazonia. We find that the hydrogen isotopic composition of leaf wax molecules (specifically the C28 n-alkanoic acid) carried by this tropical mountain river largely records the elevation gradient defined by the isotopic composition of precipitation, and this supports the general interpretation of these biomarkers as proxy recorders of catchment conditions. However, we also find that leaf wax isotopic composition varies with river flow regime over storm and seasonal timescales, which could in some cases be quantitatively significant relative to changes in the isotopic composition of precipitation in the past. Our results inform on the sourcing and transport of material by a major tributary of the Amazon River and contribute to the spatial interpretation of sedimentary records of past climate using the leaf wax proxy.
Author Posting. © American Geophysical Union, 2014. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 41 (2014): 6420–6427, doi:10.1002/2014GL061328.
Suggested CitationGeophysical Research Letters 41 (2014): 6420–6427
Showing items related by title, author, creator and subject.
Repeated pulses of vertical methane flux recorded in glacial sediments from the southeast Bering Sea Cook, Mea S.; Keigwin, Lloyd D.; Birgel, Daniel; Hinrichs, Kai-Uwe (American Geophysical Union, 2011-05-11)There is controversy over the role of marine methane hydrates in atmospheric methane concentrations and climate change during the last glacial period. In this study of two sediment cores from the southeast Bering Sea (700 ...
Paleoreconstruction of organic carbon inputs to an oxbow lake in the Mississippi River watershed : effects of dam construction and land use change on regional inputs Bianchi, Thomas S.; Galy, Valier; Rosenheim, Brad E.; Shields, Michael; Cui, Xingqian; Van Metre, Peter (John Wiley & Sons, 2015-10-10)We use a dated sediment core from Lake Whittington (USA) in the lower Mississippi River to reconstruct linkages in the carbon cycling and fluvial sediment dynamics over the past 80 years. Organic carbon (OC) sources were ...
Organic geochemistry of the early Toarcian oceanic anoxic event in Hawsker Bottoms, Yorkshire, England French, Katherine L.; Sepulveda, Julio; Trabucho-Alexandre, J.; Grocke, Darren R.; Summons, Roger E. (2013-12)A comprehensive organic geochemical investigation of the Hawsker Bottoms outcrop section in Yorkshire, England has provided new insights about environmental conditions leading into and during the Toarcian oceanic anoxic ...