On the stratigraphic integrity of leaf-wax biomarkers in loess paleosols

Häggi, C., Zech, R., Mcintyre, C. , Zech, M. and Eglinton, T.I. (2014) On the stratigraphic integrity of leaf-wax biomarkers in loess paleosols. Biogeosciences, 11(9), pp. 2455-2463. (doi: 10.5194/bg-11-2455-2014)

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Paleoenvironmental and paleoclimate reconstructions based on molecular proxies, such as those derived from leaf-wax biomarkers, in loess-paleosol sequences represent a promising line of investigation in Quaternary research. The main premise of such reconstructions is the synsedimentary deposition of biomarkers and dust, which has become a debated subject in recent years. This study uses two independent approaches to test the stratigraphic integrity of leaf-wax biomarkers: (i) long-chain n-alkanes and fatty acids are quantified in two sediment-depth profiles in glacial till on the Swiss Plateau, consisting of a Holocene topsoil and the underlying B and C horizons. Since glacial sediments are initially very poor in organic matter, significant amounts of leaf-wax biomarkers in the B and C horizons of those profiles would reflect postsedimentary root-derived or microbial contributions. (ii) Compound-specific radiocarbon measurements are conducted on n-alkanes and n-alkanoic (fatty) acids from several depth intervals in the loess section "Crvenka", Serbia, and the results are compared to independent estimates of sediment age. We find extremely low concentrations of plant-wax n-alkanes and fatty acids in the B and C horizons below the topsoils in the sediment profiles. Moreover, compound-specific radiocarbon analysis yields plant-wax 14C ages that agree well with published luminescence ages and stratigraphy of the Serbian loess deposit. Both approaches confirm that postsedimentary, root-derived or microbial contributions are negligible in the two investigated systems. The good agreement between the ages of odd and even homologues also indicates that reworking and incorporation of fossil leaf waxes is not particularly relevant either.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Mcintyre, Dr Cameron
Authors: Häggi, C., Zech, R., Mcintyre, C., Zech, M., and Eglinton, T.I.
College/School:College of Science and Engineering > Scottish Universities Environmental Research Centre
Journal Name:Biogeosciences
Publisher:European Geosciences Union ; Copernicus Publications
ISSN (Online):1726-4189
Copyright Holders:Copyright © 2014 The Authors
First Published:First published in Biogeosciences 11:2455-2463
Publisher Policy:Reproduced under a Creative Commons licence

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