Geomicrobiology of Fe-rich sediments of Lake Towuti

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The GeoFeLT project investigates the geomicrobiology and biogeochemistry of the iron-rich sediment of Lake Towuti, Sulawesi Island, Indonesia, as part of the ICDP drilling campaign. Based on the results from two pilot studies three major hypotheses were formulated: 1. Due to the high abundance of iron and other metals in the water column and sediment of Lake Towuti they play a key role in biogeochemical cycling. 2. Lake Towuti is a modern analogue to the ferrouginous oceans of the Archaea and allow studying early diagenesis of such systems in great detail. 3. The paleoclimatic changes since the formation of the lake are recorded not just in sedimentological and chemical parameters but in the current and extant microbial community or in their DNA as well.In summer 2015 the drilling was carried out successfully. For the first time in ICDP history a dedicated core for destructive microbiological and geochemical analyses was recovered. During the extensive on-site sampling and processing transient parameters were measured immediately, other samples were preserved according to their respective requirements. A total of 5 groups work in this research area. The analyses that were carried out by the GeoFeLT team members were are closely coordinated with the other research groups in order to achieve the best possible coverage. The PhD student of the GeoFeLT project tests the hypotheses through a wide range of analyses, especially pore water chemistry, turnover rate measurements with radiotracers as well as molecular and microbiological analyses. The preliminary data indicate that hypothesis 1 will be confirmed, hypothesis 2 disproved because local phenomena have too much influence on the system to draw any general conclusions, for hypothesis 3 the age model and the paleoenvironmental reconstruction will be provided by other groups and is not yet available. One paper has been published, another one is in submitted. This application requests a 12-month extension of the running PhD project until the end of the planned 3-year project.