Intensified microbial sulfate reduction in the deep Dead Sea during the early Holocene Mediterranean sapropel 1 deposition.

Autor: Levy EJ; Department of Earth and Environmental Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel.; Geological Survey of Israel, Jerusalem, Israel.; Department of Climate Geochemistry, Max Planck Institute for Chemistry, Mainz, Germany., Thomas C; Department of Earth Sciences, University of Geneva, Geneva, Switzerland., Antler G; Department of Earth and Environmental Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel.; The Interuniversity Institute for Marine Sciences in Eilat, Eilat, Israel., Gavrieli I; Geological Survey of Israel, Jerusalem, Israel., Turchyn AV; Department of Earth Sciences, University of Cambridge, Cambridge, UK., Grossi V; Laboratoire de Géologie de Lyon, Univ. Lyon 1, CNRS, ENSL, Villeurbanne, France., Ariztegui D; Department of Earth Sciences, University of Geneva, Geneva, Switzerland., Sivan O; Department of Earth and Environmental Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel.
Jazyk: angličtina
Zdroj: Geobiology [Geobiology] 2022 Jul; Vol. 20 (4), pp. 518-532. Date of Electronic Publication: 2022 Apr 05.
DOI: 10.1111/gbi.12493
Abstrakt: The hypersaline Dead Sea and its sediments are natural laboratories for studying extremophile microorganism habitat response to environmental change. In modern times, increased freshwater runoff to the lake surface waters resulted in stratification and dilution of the upper water column followed by microbial blooms. However, whether these events facilitated a microbial response in the deep lake and sediments is obscure. Here we investigate archived evidence of microbial processes and changing regional hydroclimate conditions by reconstructing deep Dead Sea chemical compositions from pore fluid major ion concentration and stable S, O, and C isotopes, together with lipid biomarkers preserved in the hypersaline deep Dead Sea ICDP-drilled core sediments dating to the early Holocene (ca. 10,000 years BP). Following a significant negative lake water balance resulting in salt layer deposits at the start of the Holocene, there was a general period of positive net water balance at 9500-8300 years BP. The pore fluid isotopic composition of sulfate exhibit evidence of intensified microbial sulfate reduction, where both δ 34 S and δ 18 O of sulfate show a sharp increase from estimated base values of 15.0‰ and 13.9‰ to 40.2‰ and 20.4‰, respectively, and a δ 34 S vs. δ 18 O slope of 0.26. The presence of the n-C 17 alkane biomarker in the sediments suggests an increase of cyanobacteria or phytoplankton contribution to the bulk organic matter that reached the deepest parts of the Dead Sea. Although hydrologically disconnected, both the Mediterranean Sea and the Dead Sea microbial ecosystems responded to increased freshwater runoff during the early Holocene, with the former depositing the organic-rich sapropel 1 layer due to anoxic water column conditions. In the Dead Sea prolonged positive net water balance facilitated primary production and algal blooms in the upper waters and intensified microbial sulfate reduction in the hypolimnion and/or at the sediment-brine interface.
(© 2022 The Authors. Geobiology published by John Wiley & Sons Ltd.)
Databáze: MEDLINE
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