Microorganisms are able to cause, but also to inhibit or protect against corrosion. Corrosion inhibition by microbial processes may be due to the formation of mineral deposition layers on metal objects. Such deposition layers have been found in archaeological studies on ancient metal objects, buried in soil, which were hardly corroded. Recent field investigations showed that natural mineral deposition layers can be found on sheet piles in soil. We investigated the microbial communities of these deposition layers and the adjacent soil. Our data, from five different sampling sites, all show striking differences between microbial communities of the deposition layer versus the adjacent soil over the depth profile. Bacterial species dominated in top soil while archaeal sequences increased in abundance with depth. All mineral deposition layers from the steel surface were dominated by Euryarchaeota, of which almost all sequences were phylogenetically related with the Methanobacteria genus. The mineral layer consisted of carbonate precipitates. Based on 16S rDNA gene sequencing data we hypothesize that the methanogens directly extract electrons from the metal surface, thereby, initially inducing mild corrosion, but simultaneously, inducing carbonate precipitation. This, will cause encrustation of the archaea, which drastically slow down their activity and create a natural protective layer against further corrosion.

Faculty of Civil Engineering and Geosciences Department of Geotechnology Master of Science by Michael Afanasyev B.Sc. A Ground Penetrating Radar (GPR) survey was conducted in April of 2008, collecting 27 km of radar profiles in Sandflugtdalen, a permafrosted glacio-fluvial bedrock valley in West Greenland. Due to low electric permittivity of frozen soil, GPR has good depth penetration of permafrost, up to 80 m using low-frequency (50 MHz) antennae.Resolution of reflections from subsurface structures are improved by gain application and frequency filtering. Migration reconstructs the radar image to make it look more like the geological structure in the subsurface. Using the principles of radar stratigraphy, 6 types of radar facies are identified in the dataset -chaotic (shallow), parallel, subparallel, oblique, chaotic with reflection and chaotic (deep); the facies are interpreted respectively as non-geological artifacts, related to system problems, lacustrine deposits (both parallel and sub-parallel facies), delta foresets, glacial till and/or moraine deposits, and bedrock. Average bedrock depth in Sandflugtdalen is ∼ 50 meter. Bedrock barriers, overlaid by push moraines, divide Sandflugtdalen in 3 subbasins. Radar packages of delta foresets, till and lacustrine deposits in each subbasin are interpreted to be have been deposited in at least 3 individual moraine-dammed lakes, that existed in front of the glacier during glacial retreat, between 10.5 ka ago and ∼ 5 ka ago. A 3-D model of the bedrock surface is generated and based on the model the sediment volume in the mapped area is calculated as 0.37 km 3 . Modeling the bedrock and mapping the sedimentary architecture in a filled glacial valley generates a base-case for model validation of short-term climate changes and effects on glacier and sedimentary system. PrefaceDuring the past two years, I have followed the Joint Master's in Applied Geophysics, a two-year programme offered by the IDEA League partners -TU Delft, ETH Zurich and RWTH Aachen. I have attended courses, conducted experiments, written reports and passed exams with fellow students from 10 different countries. Together, we have partied, traveled, climbed mountains and have learned a lot not only about geophysics but also about each other. It has been a truly unique experience.The last part of the Joint Master's programme is dedicated to thesis project. This report is written as part of the graduation thesis work, that I have done at the