Bobrovskiy, I., Poulton, S.W. orcid.org/0000-0001-7621-189X, Hope, J.M. et al. (1 more author) (2024) Impact of aerobic reworking of biomass on steroid and hopanoid biomarker parameters recording ecological conditions and thermal maturity. Geochimica et Cosmochimica Acta, 364. pp. 114-128. ISSN 0016-7037
Abstract
Steranes and hopanes are the biomarkers of eukaryotic sterols and bacterial hopanols. Extracted from sedimentary rock, they are widely used to assess burial temperatures and palaeoecological conditions. The relative proportion of steranes and hopanes is commonly applied as a measure of the flux of eukaryotic versus bacterial biomass into sediments, and the relative abundances of C27, C28 and C29 steranes are proxies for shifts in eukaryote ecology. In Recent sediments, intact sterols provide additional information about particular eukaryotic origins. However, biological lipid distributions are not always recorded faithfully in sediments. Based on observations on modern algae and plants, and on 558 million year old fossil macroalgae from the Ediacaran of the White Sea, we suggest that these biomarker proxies can be severely altered by aerobic microbial reworking, to the extent that a complete loss of primary ecological information may occur. Network analysis on the biomarker data suggests that oxic degradation also affects isomer and homolog distributions of saturated and aromatic steroids, hopanes, cheilanthanes and n-alkanes, generating anomalies in apparent thermal maturity indicators and other proxies. In our dataset, between Ediacaran macroalgae that experienced the least and the most oxic degradation, the absolute concentration of biomarkers decreases 80-fold, and at the same time the proportion of steranes over hopanes decreases by a factor of 82, while the proportion of C29 steranes among total steranes decreases from 91% to 47%. Such redox dependent offsets may explain the recurrently erratic behaviour of numerous biomarker parameters. While these results impart constraints on the interpretation of biomarker distributions, they do provide a tool for evaluating the effects of oxygen exposure and microbial degradation on organic matter preservation in recent and ancient environments and may point towards a solution for the correction of such effects.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2023 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Environment (Leeds) > School of Earth and Environment (Leeds) > Earth Surface Science Institute (ESSI) (Leeds) |
Funding Information: | Funder Grant number Royal Society WM150108 |
Depositing User: | Symplectic Publications |
Date Deposited: | 28 Nov 2023 14:35 |
Last Modified: | 19 Dec 2023 17:14 |
Status: | Published |
Publisher: | Elsevier |
Identification Number: | 10.1016/j.gca.2023.11.024 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:206006 |