title: Ultra-high-resolution paleoenvironmental records via direct laser-based analysis of lipid biomarkers in sediment core samples.
abstract: Marine microorganisms adapt to their habitat by structural modification of their membrane lipids. This concept is the basis of numerous molecular proxies used for paleoenvironmental reconstruction. Archaeal tetraether lipids from ubiquitous marine planktonic archaea are particularly abundant, well preserved in the sedimentary record and used in several molecular proxies. We here introduce the direct, extraction-free analysis of these compounds in intact sediment core sections using laser desorption ionization (LDI) coupled to Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS). LDI FTICR-MS can detect the target lipids in single submillimeter-sized spots on sediment sections, equivalent to a sample mass in the nanogram range, and could thus pave the way for biomarker-based reconstruction of past environments and ecosystems at subannual to decadal resolution. We demonstrate that ratios of selected archaeal tetraethers acquired by LDI FTICR-MS are highly correlated with values obtained by conventional liquid chromatography/MS protocols. The ratio of the major archaeal lipids, caldarchaeol and crenarchaeol, analyzed in a 6.2-cm intact section of Mediterranean sapropel S1 at 250-µm resolution (∼ 4-y temporal resolution), provides an unprecedented view of the fine-scale patchiness of sedimentary biomarker distributions and the processes involved in proxy signal formation. Temporal variations of this lipid ratio indicate a strong influence of the ∼ 200-y de Vries solar cycle on reconstructed sea surface temperatures with possible amplitudes of several degrees, and suggest signal amplification by a complex interplay of ecological and environmental factors. Laser-based biomarker analysis of geological samples has the potential to revolutionize molecular stratigraphic studies of paleoenvironments.
authors.affiliation: Organic Geochemistry Group, MARUM Center for Marine Environmental Sciences and Department of Geosciences, University of Bremen, 28359 Bremen, Germany; khinrichs@uni-bremen.de lwoermer@marum.de.
authors.forename: Lars
authors.initials: L
authors.lastname: Wörmer
authors.affiliation: Organic Geochemistry Group, MARUM Center for Marine Environmental Sciences and Department of Geosciences, University of Bremen, 28359 Bremen, Germany;
authors.forename: Marcus
authors.initials: M
authors.lastname: Elvert
authors.affiliation: Fourier Transform Mass Spectrometry Applications-Development, Bruker Daltonik GmbH, 28359 Bremen, Germany;
authors.forename: Jens
authors.initials: J
authors.lastname: Fuchser
authors.affiliation: Organic Geochemistry Group, MARUM Center for Marine Environmental Sciences and Department of Geosciences, University of Bremen, 28359 Bremen, Germany;
authors.forename: Julius Sebastian
authors.initials: JS
authors.lastname: Lipp
authors.affiliation: Organic Geochemistry Group, MARUM Center for Marine Environmental Sciences and Department of Geosciences, University of Bremen, 28359 Bremen, Germany; Helmholtz-Gemeinschaft Max-Planck-Gesellschaft Research Group on Deep-Sea Ecology and Technology, Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung, 27570 Bremerhaven, Germany; and.
authors.forename: Pier Luigi
authors.initials: PL
authors.lastname: Buttigieg
authors.affiliation: Inorganic Geochemistry Group, MARUM Center for Marine Environmental Sciences and Department of Geosciences, University of Bremen, 28359 Bremen, Germany.
authors.forename: Matthias
authors.initials: M
authors.lastname: Zabel
authors.affiliation: Organic Geochemistry Group, MARUM Center for Marine Environmental Sciences and Department of Geosciences, University of Bremen, 28359 Bremen, Germany; khinrichs@uni-bremen.de lwoermer@marum.de.
authors.forename: Kai-Uwe
authors.initials: KU
authors.lastname: Hinrichs
mesh_terms: D059001:Aquatic Organisms / Q000737:chemistry*; D001105:Archaea / Q000737:chemistry*; D019015:Geologic Sediments / Q000737:chemistry*; D008055:Lipids / Q000737:chemistry*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods
chemical_list: D008055:Lipids
keywords: FTICR-MS; archaeal tetraether lipids; laser desorption ionization; molecular stratigraphy; solar cycle