at the Swiss Federal Institute of Aquatic Science and Technology, eawag.

Lake Baikal is the largest freshwater reservoir on earth, and is very oligotrophic and pristine in most parts. It lies in a tectonic rift zone, is 25-30 mio years old and holds some 7 km of sediments. Well-structured layers of Fe and Mn oxides form at the redox interface of these sediments at some locations. 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. At present, however, it is not clear under what circumstances the crusts are formed and buried. The aim of the PhD project is the characterization of the controlling physical and biogeochemical processes occurring in the diagenesis of these sediment layers, and to describe their mineral composition.

Dissolution, precipitation, and the timescale of diffusive processes within the sediment have to be quantified. The contents of major and trace elements in undisturbed core sections will be analyzed with spatial resolution in the sub-millimeter range by state-of-the-art scanning methods. In addition, solid phases will be characterized by spectroscopic techniques to gain information on the speciation and main mineral forms of Fe and Mn across the redox interface and on associated trace elements. Bacteria are involved in the sediment diagenetic processes and must be characterized as well. With the rate estimates of diagenetic formation and dissolution of Fe/Mn layers, and the vertically changing diffusion coefficients of ions, the temporal dynamics of the formation and dissolution of Fe/Mn layers, and their dependence on key parameters shall be evaluated using a dynamic sediment model.

The thesis will be headed by the director of Eawag, Prof. Janet Hering, and supervised by Drs. Beat Müller, Andrea Ulrich, and Andreas Vögelin.

Workplace: Eawag, Kastanienbaum (Dept. of Surface Waters - Research and Management http://www.eawag.ch/organisation/index_EN).

Keywords: geochemistry, sediments, trace metals, porewater, minerals, laser ablation, spectroscopy

Beginning: Summer 2009 (or until filled) - for 3.5 years;

Education: The applicant holds a Diploma or Master Degree in Environmental or Earth Sciences (or related). She/he should be familiar with lake internal processes and early diagenesis in sediments, and have some knowledge on trace element analyses and modeling. Good command in oral and written English is a requirement.

Remarks: Applications with a CV and a brief description of experience and interests, as well as the names and affiliations of two references, to be sent to Beat Müller, Eawag, CH-6047 Kastanienbaum, eawag9041@earthworks-jobs.com. Interviews will take place in June 2009. Afterwards, the position is open until filled.

Dr. Beat Müller, Eawag, CH-6047 Kastanienbaum, eawag9041@earthworks-jobs.com
Dr. Andrea Ulrich, Empa, CH-8600 Dübendorf, andrea.ulrich@empa.ch
Dr. Andreas Voegelin, Eawag, CH-8600 Dübendorf, andreas.voegelin@eawag.ch

Link: http://www.eawag.ch/organisation/abteilungen/surf/schwerpunkte/project_overview/lbaikal/baikal_EN