气候变化领域集成服务门户(CCPortal): Deoxygenation dynamics on the western Nile deep-sea fan during sapropel S1 from seasonal to millennial timescales

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DOI	10.5194/cp-17-1025-2021
	Deoxygenation dynamics on the western Nile deep-sea fan during sapropel S1 from seasonal to millennial timescales
	Blanchet C.L.; Tjallingii R.; Schleicher A.M.; Schouten S.; Frank M.; Brauer A.
发表日期	2021
ISSN	1814-9324
起始页码	911
结束页码	931
卷号	17 期号:3
英文摘要	Ocean deoxygenation is a rising threat to marine ecosystems and food resources under present climate warming conditions. Organic-rich sapropel layers deposited in the Mediterranean Sea provide a natural laboratory to study the processes that have controlled changes in seawater oxygen levels in the recent geological past. Our study is based on three sediment cores spanning the last 10 000 years and located on a bathymetric transect offshore from the western distributaries of the Nile delta. These cores are partly to continuously laminated in the sections recording sapropel S1, which is indicative of bottom-water anoxia above the western Nile deep-sea fan. We used a combination of microfacies analyses and inorganic and organic geochemical measurements to reconstruct changes in oxygenation conditions at seasonal to millennial timescales. Millimetre-Thick laminations are composed of detrital, biogenic and chemogenic sublayers reflecting seasonal successions of sedimentation. Dark layers reflect the deposition of summer floods and two types of light layers correspond to autumn plankton blooms and authigenic carbonates formed in the water column during spring early summer, respectively. The isotopic signature of the authigenic carbonates suggests permanent anoxic to euxinic bottom waters resulting in high levels of anaerobic remineralization of organic matter and highlights their potential to reconstruct seawater chemistry at times when benthic fauna was absent. Ratios of major elements combined with biomarkers of terrestrial and marine organic matter and redox-sensitive compounds allow changes in terrigenous input, primary productivity and past deoxygenation dynamics on millennial timescales to be tracked. Rapid fluctuations of oxygenation conditions in the upper 700m water depth occurred above the Nile deep-sea fan between 10 and 6.5 ka BP, while deeper cores recorded more stable anoxic conditions. Synchronous changes in terrigenous input, primary productivity and past oxygenation dynamics after 6.5 ka BP show that runoff-driven eutrophication played a central role in rapid oxygenation changes in the south-eastern Levantine Basin. These findings are further supported by other regional records and reveal time-Transgressive changes in oxygenation state driven by rapid changes in primary productivity during a period of long-Term deep-water stagnation. © 2021 Copernicus GmbH. All rights reserved.
来源期刊	Climate of the Past
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/183574
作者单位	Gfz German Research Centre for Geosciences Potsdam, Section of Climate and Landscape Dynamics, Telegrafenberg, Potsdam, 14743, Germany; Gfz German Research Centre for Geosciences Potsdam, Section of Inorganic and Isotope Geochemistry, Telegrafenberg, Potsdam, 14743, Germany; Royal Nioz, Department of Marine Microbiology and Biogeochemistry, Landsdiep 4, SZ 't Horntje, Texel, 1797, Netherlands; Department of Earth Sciences, University of Utrecht, Utrecht, Netherlands; Geomar Helmholtz Centre for Ocean Research Kiel, Research Unit Paleoceanography, Wischhofstrasse 1-3, Kiel, 24148, Germany
推荐引用方式 GB/T 7714	Blanchet C.L.,Tjallingii R.,Schleicher A.M.,et al. Deoxygenation dynamics on the western Nile deep-sea fan during sapropel S1 from seasonal to millennial timescales[J],2021,17(3).
APA	Blanchet C.L.,Tjallingii R.,Schleicher A.M.,Schouten S.,Frank M.,&Brauer A..(2021).Deoxygenation dynamics on the western Nile deep-sea fan during sapropel S1 from seasonal to millennial timescales.Climate of the Past,17(3).
MLA	Blanchet C.L.,et al."Deoxygenation dynamics on the western Nile deep-sea fan during sapropel S1 from seasonal to millennial timescales".Climate of the Past 17.3(2021).