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Fossilization and degradation of intact polar lipids in deep subsurface sediments: A theoretical approach

Schouten, S. and Middelburg, J.J. and Hopmans, E.C. and Damsté Sinninghe, J.S. (2010) Fossilization and degradation of intact polar lipids in deep subsurface sediments: A theoretical approach. Geochimica et Cosmochimica Acta, 74, 3806-3814. ISSN 0016-7037.

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Official URL: http://dx.doi.org/10.1016/j.gca.2010.03.029

Abstract

Intact polar membrane lipids (IPLs) are frequently used as markers for living microbial cells in sedimentary environments. The assumption with these studies is that IPLs are rapidly degraded upon cell lysis and therefore IPLs present in sediments are derived from in situ microbial production. We used a theoretical approach to assess whether IPLs in surface sediments can potentially represent fossilized IPLs derived from the upper part of the water column and whether IPLs can be preserved during sediment burial. Previous studies which examined the degradation kinetics of IPLs show that phospholipids, i.e. ester-linked lipids with a phosphor-containing head group, degrade more rapidly than glycosidic ether lipids, i.e. ether-linked lipids with a glycosidically bound sugar moiety. Based on these studies, we calculate that only a minor fraction of phospholipids but a major fraction of glycosidic ether lipids biosynthesized in the upper part of the water column can potentially reach deep-sea surface sediments. Using a simple model and power law kinetic degradation parameters reported in the literature, we also evaluated the degradation of IPLs during sediment burial. Our model predicts a log–log relationship between IPL concentrations and depth, consistent with what has been observed in studies of IPLs in subsurface sediments. Although our results do not exclude production of IPLs in subsurface sediment, they do suggest that IPLs present in the deep biosphere may contain a substantial fossil component potentially masking in situ IPL production.

Item Type:Article
Institutes:Nederlands Instituut voor Ecologie (NIOO)
ID Code:6432
Deposited On:01 Jul 2010 02:00
Last Modified:04 Sep 2014 09:57

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