Iron sulfides in Baldeggersee during the last 8000 years: formation processes, chemical speciation and mineralogical constraints from EXAFS spectroscopy

The goal of this study was the interpretation of iron and sulfur records in the sediment of Baldeggersee. The hypothesis that climatic factors affect deep-water mixing in the lake and leave their mark in the iron sulfide record of the sediments was tested quantitatively on short sediment cores. The...

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Bibliographic Details
Main Author: Bott, Markus
Other Authors: Wehrli, B. (thesis advisor), Manceau, A. (thesis advisor), Sigg, L. (thesis advisor)
Format: Doctoral or Postdoctoral Thesis
Language:English
Published: ETH Zürich 2002
Subjects:
Online Access:https://doi.org/10.3929/ethz-a-004424837
Description
Summary:The goal of this study was the interpretation of iron and sulfur records in the sediment of Baldeggersee. The hypothesis that climatic factors affect deep-water mixing in the lake and leave their mark in the iron sulfide record of the sediments was tested quantitatively on short sediment cores. The speciation of iron and sulfur was analyzed with a combination of wet chemical and spectroscopic methods. Information on the transport and the chemical and microbial transformation of iron and sulfur at the sediment-water interface was obtained from a process study on recent sediments. The results of these measurements were then used in a second step to interpret the iron sulfide stratigraphy in a long sediment core covering several thousand years. This paleolimnological study was focused on a preliminary analysis of the oscillating varve regime of Baldeggersee. By comparison with recent paleoceanographic literature potential links between the North Atlantic climate oscillations and the iron sulfide record in the partially varved sediments from Baldeggersee were explored. [.] Die vorliegende Arbeit hatte zum Ziel, die Eisen- und Sulfidprofile in den Sedimenten des Baldeggersees zu interpretieren. Klimatische Faktoren beeinflussen die Tiefenwassenwassermischung und damit die Redoxverhältnisse im See. In dieser Studie wurde die Hypothese geprüft, dass klimatische Schwankungen die Eisensulfidkonzentration im Sediment beeinflussen. Dazu wurde die Speziierung von Fe und S mit einer Kombination von chemischen und spektroskopischen Methoden analysiert. Mit einer Prozessstudie wurden Transport und Transformation von Fe und S im Sediment quantifziert. Die Resultate dieser Studie an Kurzkernen wurden dann in einer Langkernstudie angewandt, um die Schwankungen in der FeS Sedimentation über mehrere Tausend Jahre zu interpretieren. Diese paleolimnologische Studie hatte zum Ziel, die Oszillationen in der Ablagerung von Varven zu analysieren und mit neuen Ergebnissen zu Klimaschwankungen im Nordatlantik zu verknüpfen. [.]