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

Häggi, C.; Zech, Roland; McIntyre, C.; Zech, M.; Eglinton, T. I. (2014). On the stratigraphic integrity of leaf-wax biomarkers in loess paleosols. Biogeosciences, 11(9), pp. 2455-2463. Copernicus Publications 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:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Institute of Geography > Physical Geography > Unit Biogeochemistry and Paleoclimate
08 Faculty of Science > Institute of Geography

UniBE Contributor:

Zech, Roland

Subjects:

900 History > 910 Geography & travel

ISSN:

1726-4170

Publisher:

Copernicus Publications

Language:

English

Submitter:

Monika Wälti-Stampfli

Date Deposited:

06 Oct 2014 15:51

Last Modified:

01 Oct 2015 16:26

Publisher DOI:

10.5194/bg-11-2455-2014

BORIS DOI:

10.7892/boris.58515

URI:

https://boris.unibe.ch/id/eprint/58515

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