From Andes to Amazon: assessing branched tetraether lipids as tracers for soil organic carbon in the Madre de Dios River system
Kirkels, Frédérique M. S. A.
West, A. Joshua
Feakins, Sarah J.
MetadataShow full item record
Keywordbacterial membrane lipids (brGDGTs); altitude‐temperature relations; Amazon headwaters; soil‐river connectivity; riverine organic carbon transport, brGDGT proxy signal
We investigate the implications of upstream processes and hydrological seasonality on the transfer of soil organic carbon (OC) from the Andes mountains to the Amazon lowlands by the Madre de Dios River (Peru), using branched glycerol dialkyl glycerol tetraether (brGDGT) lipids. The brGDGT signal in Andean soils (0.5 to 3.5 km elevation) reflects air temperature, with a lapse rate of −6.0 °C/km elevation (r 2 = 0.89, p < 0.001) and −5.6 °C/km elevation (r 2 = 0.89, p < 0.001) for organic and mineral horizons, respectively. The same compounds are present in river suspended particulate matter (SPM) with a lapse rate of −4.1 °C/km elevation (r 2 = 0.82, p < 0.001) during the wet season, where the offset in intercept between the temperature lapse rates for soils and SPM indicates upstream sourcing of brGDGTs. The lapse rate for SPM appears insensitive to an increasing relative contribution of 6‐methyl isomer brGDGTs produced within the river. River depth profiles show that brGDGTs are well mixed in the river and are not affected by hydrodynamic sorting. The brGDGTs accumulate relative to OC downstream, likely due to the transition of particulate OC to the dissolved phase and input of weathered soils toward the lowlands. The temperature‐altitude correlation of brGDGTs in Madre de Dios SPM contrasts with the Lower Amazon River, where the initial soil signature is altered by changes in seasonal in‐river production and variable provenance of brGDGTs. Our study indicates that brGDGTs in the Madre de Dios River system are initially soil derived and highlights their use to study OC sourcing in mountainous river systems.
© The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Kirkels, F. M. S. A., Ponton, C., Galy, V., West, A. J., Feakins, S. J., & Peterse, F. From Andes to Amazon: assessing branched tetraether lipids as tracers for soil organic carbon in the Madre de Dios River system. Journal of Geophysical Research-Biogeosciences, 125(1), (2020): e2019JG005270, doi:10.1029/2019JG005270.
Suggested CitationKirkels, F. M. S. A., Ponton, C., Galy, V., West, A. J., Feakins, S. J., & Peterse, F. (2020). From Andes to Amazon: assessing branched tetraether lipids as tracers for soil organic carbon in the Madre de Dios River system. Journal of Geophysical Research-Biogeosciences, 125(1), e2019JG005270.
The following license files are associated with this item:
Except where otherwise noted, this item's license is described as Attribution-NonCommercial-NoDerivatives 4.0 International
Showing items related by title, author, creator and subject.
The pulse of the Amazon: fluxes of dissolved organic carbon, nutrients, and ions from the world's largest river Drake, Travis W.; Hemingway, Jordon D.; Kurek, Martin; Peucker-Ehrenbrink, Bernhard; Brown, Kristina A.; Holmes, Robert M.; Galy, Valier; Moura, José M.; Mitsuya, Miyuki; Wassenaar, Leonard; Six, Johan; Spencer, Robert G. M. (American Geophysical Union, 2021-03-15)The Amazon River drains a diverse tropical landscape greater than 6 million km2, culminating in the world's largest export of freshwater and dissolved constituents to the ocean. Here, we present dissolved organic carbon ...
Transfer of organic carbon through marine water columns to sediments – insights from stable and radiocarbon isotopes of lipid biomarkers Wakeham, Stuart G.; McNichol, Ann P. (Copernicus Publications on behalf of the European Geosciences Union, 2014-12-10)Compound-specific 13C and 14C compositions of diverse lipid biomarkers (fatty acids, alkenones, hydrocarbons, sterols and fatty alcohols) were measured in sinking particulate matter collected in sediment traps and from ...
Sources and accumulation of organic carbon in the Pearl River Estuary surface sediment as indicated by elemental, stable carbon isotopic, and carbohydrate compositions He, B.; Dai, Minhan; Huang, W.; Liu, Q.; Chen, H.; Xu, Li (Copernicus Publications on behalf of the European Geosciences Union, 2010-10-28)Organic matter in surface sediments from the upper reach of the Pearl River Estuary and Lingdingyang Bay, as well as the adjacent northern South China Sea shelf was characterized using a variety of techniques, including ...