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Diagenetic evolution and mineral composition of Fe/Mn layers in the sediments of Lake Baikal

Gesuchsteller/in Müller Beat
Nummer 124411
Förderungsinstrument Projektförderung (Abt. I-III)
Forschungseinrichtung Eawag
Hochschule Eidg. Anstalt für Wasserversorgung, Abwasserreinigung und Gewässerschutz - EAWAG
Hauptdisziplin Hydrologie, Limnologie, Glaziologie
Beginn/Ende 01.08.2009 - 31.07.2012
Bewilligter Betrag 255'475.00
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Keywords (10)

Lake Baikal; lake sediments; early diagenesis; sorption of trace metals; Fe/Mn precipitates; laser-ablation plasma mass spectrometry; EXAFS; porewaters; synchrotron spectroscopy; laser ablation plasma mass spectrometry

Lay Summary (Englisch)

Lead
Lay summary
The aim of this project is the investigation of the geochemical lifecycle and the mineral structures of the authigenic ferromanganese layers occurring in the sediments of Lake Baikal. The riddle to be solved is: are the Fe/Mn layers formed under steady-state diagenetic conditions of reductive dissolu-tion and oxidative precipitation, or are they an indicator of changing sedimentary inputs? In the former case such concretions represent ideal model systems to study the kinetics and mechanisms of geo-chemical processes at redox boundaries. In the second case the prevalence of recent and older relict layers could be used as proxy indicators for environmental change in this unique continental archive.The Fe/Mn precipitates initially form at the redox interface of lacustrine sediments. In Lake Baikal, re-mains of such layers are buried in the sediment and bear the possibility to be used as proxy indicators of past global changes in climatic conditions, as relics of them have been found in sediment layers as old as 65'000 (and up to 85'000) years. At present it is not clear under what circumstances the crusts are buried. Among the possible forcing factors are: change of the MAR of organic carbon, change of the sedimentation rate and/or the fraction of allochthonous input changing the MAR of Fe and Mn, a decline in the provision of the bottom water with oxygen, deposition of turbidites, increase of crust density and subsequent decrease of sediment porosity and, thus, diffusivity due to ageing, and others.We will gather information on the dissolution, precipitation, and the timescale of diffusive processes within the sediment by sampling of sediment and porewater with high spatial resolution and subse-quent chemical analyses. Major and trace metal contents of undisturbed core sections will also be analyzed with spatial resolution in the sub-millimeter range by scanning methods such as micro-X-ray fluorescence spectrometry (µXRF) and laser ablation inductively coupled plasma-mass spectrometry (LA-ICP-MS). In addition, solid phases will be characterized with X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS) to gain information on the speciation and main mineral forms of Fe and Mn across the redox interface, and associated trace elements. With the rate estimates of diagenetic formation and dissolution of Fe/Mn layers, and the vertically changing diffusion coefficients of Fe2+ and Mn2+ across the Fe/Mn layers, the temporal dynamics of the formation and dissolution of Fe/Mn layers, and their dependence on key parameters will be evalu-ated using a dynamic sediment model.
Direktlink auf Lay Summary Letzte Aktualisierung: 21.02.2013

Verantw. Gesuchsteller/in und weitere Gesuchstellende

Mitarbeitende

Publikationen

Publikation
Elevated uranium concentrations in Lake Baikal sediments: Burial and early diagenesis
(2016), Elevated uranium concentrations in Lake Baikal sediments: Burial and early diagenesis, in Chemical Geology, 441, 92-105.
Early diagenetic processes generate iron and manganese oxide layers in the sediments of Lake Baikal, Siberia
(2014), Early diagenetic processes generate iron and manganese oxide layers in the sediments of Lake Baikal, Siberia, in Environmental Science - Processes & Impacts, 16, 879-889.
Rare earth elements in the sediments of Lake Baikal
(2014), Rare earth elements in the sediments of Lake Baikal, in Chemical Geology, 376, 61-75.
New insights into the formation and burial of Fe/Mn accumulations in Lake Baikal sediments
(2012), New insights into the formation and burial of Fe/Mn accumulations in Lake Baikal sediments, in Chemical Geology, 330-331, 244-259.

Wissenschaftliche Veranstaltungen

Aktiver Beitrag

Titel Art des Beitrags Titel des Artikels oder Beitrages Datum Ort Beteiligte Personen
Goldschmidt 2013, Florence (Italy). 25.08. - 30.08.2013 Poster Rare Earth Elements in the Sediments of Lake Baikal 25.08.2013 Florenz, Italien Och Lawrence; Müller Beat;
Goldschmidt, Florence, Italy, August 2013 Vortrag im Rahmen einer Tagung On-site pore water measurements of Lake Baikal sediments 12.08.2013 Florenz, Italien Müller Beat; Och Lawrence;
Geochemistry. Department of Earth Sciences, University of Hongkong (China), Seminar series. 26.04.2013. Invited Talk Vortrag im Rahmen einer Tagung The Wonders of Lake Baikal and its intriguing sedimentary Geochemistry 26.04.2013 Hongkong, Hongkong Och Lawrence; Müller Beat;
ASLO New Orleans, 18-21 February 2013 Vortrag im Rahmen einer Tagung Formation and burial of Fe/Mn accumulations in Lake Baikal sediments: A modeling approach. 18.02.2013 New Orleans, Vereinigte Staaten von Amerika Och Lawrence; Müller Beat;
Swiss Geoscience Meeting, Bern, 16/17 November 2012. Vortrag im Rahmen einer Tagung Formation and burial of Fe/Mn accumulations in Lake Baikal sediments: a modeling approach. 16.11.2012 Bern, Schweiz Och Lawrence; Müller Beat;


Verbundene Projekte

Nummer Titel Start Förderungsinstrument
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Abstract

The aim of this project is the investigation of the geochemical lifecycle and the mineral structures of the authigenic ferromanganese layers occurring in the sediments of Lake Baikal. The riddle to be solved is: are the Fe/Mn layers formed under steady-state diagenetic conditions of reductive dissolution and oxidative precipitation, or are they an indicator of changing sedimentary inputs? In the former case such concretions represent ideal model systems to study the kinetics and mechanisms of geochemical processes at redox boundaries. In the second case the prevalence of recent and older relict layers could be used as proxy indicators for environmental change in this unique continental archive.The Fe/Mn precipitates initially form at the redox interface of lacustrine sediments. In Lake Baikal, the high bottom water oxygen supply, low sedimentation rate and the small mass accumulation rate (MAR) of organic carbon, among others, may be the key parameters that allow their existence over decades and centuries, and their growth to massive accretions. Within certain regions of the lake floor, remains of such layers are buried in the sediment and bear the possibility to be used as proxy indicators of past global changes in climatic conditions, as relics of them have been found in sediment layers as old as 65’000 (and up to 85’000) years. At present it is not clear under what circumstances the crusts are buried. Among the possible forcing factors are: change of the MAR of organic carbon, change of the sedimentation rate and/or the fraction of allochthonous input changing the MAR of Fe and Mn, a decline in the provision of the bottom water with oxygen, deposition of turbidites, increase of crust density and subsequent decrease of sediment porosity and, thus, diffusivity due to ageing, and others.We will gather information on the dissolution, precipitation, and the timescale of diffusive processes within the sediment by sampling of sediment and porewater with high spatial resolution and subsequent chemical analyses. Major and trace metal contents of undisturbed core sections will also be analyzed with spatial resolution in the sub-millimeter range by scanning methods such as micro-X-ray fluorescence spectrometry (µXRF) and laser ablation inductively coupled plasma-mass spectrometry (LA-ICP-MS). In addition, solid phases will be characterized with X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS) to gain information on the speciation and main mineral forms of Fe and Mn across the redox interface, and associated trace elements. In the present proposal we sug-gest to apply these investigations to horizontally layered formations formed under three different ambient conditions in the lake, and to analyze the spatial distribution and diagenetic fluxes of As, Mo, Cd, Sb, Zn, Se, Ni, Ca, and Sr across the authigenic Fe/Mn layers. With the rate estimates of diagenetic formation and dissolution of Fe/Mn layers, and the vertically changing diffusion coefficients of Fe2+ and Mn2+ across the Fe/Mn layers, the temporal dynamics of the formation and dissolution of Fe/Mn layers, and their dependence on key parameters will be evaluated using a dynamic sediment model.
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