Juergen Thieme

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Electrophoretic mobility, pyrene fluorescence, surface tension measurements, transmission electron microscopy on resin-embedded samples, and X-ray microscopy (XRM) were combined to characterize the aggregates formed from humic colloids and hydrolyzed-Fe species under various conditions of pH and mixing. We show that, at low coagulant concentration, the(More)
Defined, quartz-diluted mixtures of sulfur (S) compounds with different oxidation state (OS) were analyzed by K-edge XANES spectroscopy using linear combination fitting (LCF) and spectrum deconvolution by fitting several Gaussian and arctangent functions (GCF). Additionally, for different soils the S speciation as calculated by both methods was compared(More)
We investigated H2S attenuation by dissimilatory perchlorate-reducing bacteria (DPRB). All DPRB tested oxidized H2S coupled to (per)chlorate reduction without sustaining growth. H2S was preferentially utilized over organic electron donors resulting in an enriched (34S)-elemental sulfur product. Electron microscopy revealed elemental sulfur production in the(More)
The combination of high-resolution chemically sensitive soft X-ray microscopy with stereo imaging and processing techniques presented here forms a novel tool for the investigation of aqueous colloidal systems. Information about the spatial distribution within the sample is provided with small calculation effort processing just a pair of stereo micrographs.(More)
Extracellular polymeric substances (EPS) are expected to be an important source for the formation of mineral-organic associations in soil. Because such formations affect the composition of mobile and immobile organic matter as well as the reactivity of minerals, we investigated the composition of EPS before and after adsorption to goethite. Raman(More)
Owing to the short wavelengths of X-radiation X-ray microscopes allow higher resolution than optical microscopes. In contrast to electron microscopes, X-radiation can be used to study relatively thick aqueous specimens in their natural environment. X-ray microscopes require intense X-radiation, which is best provided by electron storage rings, as well as(More)
X-ray microscopy is capable of imaging particles in the nanometer size range directly with sub-micrometer spatial resolution and can be combined with high spectral resolution for spectromicroscopy studies. Two types of microscopes are common in X-ray microscopy: the transmission X-ray microscope and the scanning transmission X-ray microscope; their set-ups(More)
Using the scanning transmission X-ray microscope at BESSY II, colloidal structures from a Chernozem soil have been studied with a spatial resolution around 60 nm and a spectral resolution of 1,700 at the K-absorption edge of carbon. Elemental mapping has been used to determine the distribution of organic matter within the colloidal structures. Spectra have(More)
To test whether synchrotron-based spectromicroscopy can be used to identify spatial patterns of sulfur (S) and iron (Fe) speciation as well as relationships between the speciation of S and Fe in soil colloids or aggregates at the micrometre and sub-micrometre level, an anoxically prepared dissected soil aggregate (size approximately 1 mm(3)) was analyzed by(More)
Aquatic humic substances (HS), an important part of the dissolved organic carbon in freshwater systems, are polyfunctional natural compounds with polydisperse structure showing strong aggregation/coagulation behaviour at high HS concentrations and in the presence of metal ions. In this study, small-angle neutron scattering (SANS), small-angle X-ray(More)