Constraints in the application of the Branched and Isoprenoid Tetraether index as a terrestrial input proxy
Fietz, Susanne (Universitat Autònoma de Barcelona. Institut de Ciència i Tecnologia Ambientals)
Martínez García, Alfredo (ETH Zürich. Geologisches Institut)
Huguet, Carme (Huguet Micheo) (Universitat Autònoma de Barcelona. Institut de Ciència i Tecnologia Ambientals)
Rueda Ferrer, Gemma (Universitat Autònoma de Barcelona. Institut de Ciència i Tecnologia Ambientals)
Rosell Melé, Antoni (Universitat Autònoma de Barcelona. Institut de Ciència i Tecnologia Ambientals)

Data:	2011
Resum:	Determination of the relative inputs of aquatic autochthonous and terrestrial allochthonous organic matter into marine and lacustrine environments is essential to understanding the global carbon budget. A variety of proxies are used for this purpose, including the Branched and Isoprenoid Tetraether (BIT) index. This is calculated from the concentrations of branched glycerol dialkyl glycerol tetraethers (GDGTs), derived from unidentified terrestrial bacteria, and crenarchaeol, a marker for aquatic mesophile Thaumarchaeota (Crenarchaeota group I). As the index is a ratio, its value depends on both the crenarchaeol aquatic in situ production and the soil-derived branched GDGT input. Therefore, the BIT index reflects not only changes in the input of terrestrial or soil organic matter but also relative variations in aquatic Thaumarchaeota abundance in the water column. In fact, we show that in oceanic and lacustrine settings, the BIT index can be dominated by the aquatic end-member of the ratio. Consequently, the BIT index by itself can be an unreliable proxy to compare the input of terrestrial matter between sites and over time, and we propose that the quantification of branched GDGT fluxes or concentrations may instead be a better indicator of soil terrestrial inputs.
Ajuts:	Ministerio de Ciencia e Innovación CGL2008-03288-E Ministerio de Ciencia e Innovación CGL2010-15000 Ministerio de Ciencia e Innovación POL2006-02990
Drets:	Tots els drets reservats.
Llengua:	Anglès
Document:	Article ; recerca ; Versió publicada
Matèria:	BIT ; Branched and isoprenoid tetraether index ; Soil terrestrial
Publicat a:	Journal of geophysical research, Vol. 116, Issue 10 (Oct. 2011) , ISSN 0148-0227

DOI: 10.1029/2011JC007062

9 p, 551.3 KB

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