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Lookup NU author(s): Professor Thomas Wagner
This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).
We present elemental, lipid biomarker and compound-specific isotope (_13C, _2H) data for soils and leaf litter collected in the catchment of Lake Ohrid (Albania, Macedonia), as well as macrophytes, particulate organic matter and sediments from the lake itself. Lake Ohrid provides an outstanding archive of continental environmental change of at least 1.2Myears and the purpose of our study is to ground truth organic geochemical proxies that we developed in order to study past changes in the terrestrial biome. We show that soils dominate the lipid signal of the lake sediments rather than the vegetation or aquatic biomass, while compound-specific isotopes (_13C, _2H) determined for n-alkanoic acids confirm a dominant terrestrial source of organic matter to the lake. There is a strong imprint of suberin monomers on the composition of total lipid extracts and chain-length distributions of n-alkanoic acids, n-alcohols, !-hydroxy acids and _,!-dicarboxylic acids. Our end-member survey identifies that ratios of mid-chain length suberin-derived to long-chain length cuticular-derived alkyl compounds as well as their average chain length distributions can be used as new molecular proxies of organic matter sources to the lake. We tested these for the 8.2 ka event, a pronounced and widespread Holocene climate fluctuation. In SE Europe climate became drier and cooler in response to the event, as is clearly recognizable in the carbonate and organic carbon records of Lake Ohrid sediments. Our new proxies indicate biome modification in response to hydrological changes, identifying two phases of increased soil OM supply, first from topsoils and then from mineral soils. Our study demonstrates that geochemical fingerprinting of terrestrial OM should focus on the main lipid sources, rather than the living biomass. Both can exhibit climate-controlled variability, but are generally not identical.
Author(s): Holtvoeth J, Rushworth D, Imeri A, Cara M, Vogel H, Wagner T, Wolff GA
Publication type: Article
Publication status: Published
Journal: Biogeosciences Discussion
Online publication date: 13/08/2015
Acceptance date: 03/07/2015
Date deposited: 24/09/2015
ISSN (print): 1810-6277
ISSN (electronic): 1810-6285
Publisher: Copernicus GmbH
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