The World in a Grain of Sand: Tracing Earth surface systems through size and shapes of grains of sand
In the SedLab we analyse the compositional properties of sediments. Measuring the full range of grain size distributions from a few nanometers to centimeters and determine the shape of each single grain. Disentangling sediments allows scientists to infer the history of the sediments, interpret sedimentary archives and learn about the processes that have generated and transported the sediments.
The SedLab of the geomorphology section is fully equipped lab for measuring routinely large batches of sediments. Depending on the specific requirements of scientists the sediments need to be prepared and cleaned before analysis. We offer scientists and students from partner institutions to come for processing samples in the sediment lab or even process the samples for them depending on the workload of each specific project. We adapted the preparation routine for samples accordingly to the needs of each projects and the scientific questions.
Besides the analytical lab work we also develop numerical methods and tools to further evaluate the measurements and gain the maximum scientific information from the data. These tools are dynamically developed and can be adapted to specific user needs.
We have a fully equipped laboratory to process the sediment samples with two work spaces for sample preparation and two computer work spaces for analytical analysis and evaluation. The lab is outfitted with all equipment to chemically and physically prepare sediments for the analysis. We have shaking tables, a fume hot and large drying cupboard space designed for the fast the fast throughput of large sample batches such as for example daily resolved times series of suspended sediments or sediment cores.
Particle Analyzer CamsizerXT
In the SedLab we a Retsch CamsizerXT to analyse the the size distribution and shapes of sediments. The device uses high speed dynamic image analysis to measure in real-time the real size and shape of several million grains. Two high definition cameras are taking pictures of the projected shadows of each grain that is analysed. The software instantly calculates the grain size distribution and computes several shape parameters. We have two modules to disperse the grains for analysis one is a free-fall chute and the second is an air pressured accelerated chute that separates particles and aggregates. The measurement range of this device is between 10 μm and 3 cm. Due to the optical resolution limits the measuring range of the Camsizer can not cover clays very well and is more suited for coarser granulometries.
Laser Diffraction Particle Size Analyzer LA950
In the SedLab we have a Retsch/Horiba LA950 laser based particle size distribution analyser that uses the static scattering of laser light beams by particles of different sizes. The basic physical principle is the Fraunhofer Theory after which the intensity of scattered light is depending on the particle size. A second theory describing the scattering of electromagnetic waves on spherical objects is the Mie Theory. The later one is better suited for the interpretation of fine particles. Both models are automatically implemented in the measuring routing of our device. The advantages of static light scattering are that only a small amount of sample is needed for measuring a wide grain size range. In the SedLab we can measure grains in the size range of between 100 nm to about 3 cm. Our device is equipped with an auto sampler that allows us to run large batches of sediments and make efficient use of the machine and maximise the throughput of samples.
End-member Modelling Analysis of Grain Size Data (EMMA)
The grain size distributions of sediment deposits routed across the Earth surface contain valuable information about the source area they are derived from, the transport processes that moved them and the transport pathway. These information about the transport regime are however obscured when sediments become mixed during deposition. End-member modelling analysis or EMMA is a statistical approach to unmix the underlying transport regimes. The GNU R package EMMAgeo (GitHub) provides a coherent framework for deterministic and robust end-member modelling. For further information see the EMMAgeo website .
Grain Size Data Import and Analysis Toolbox
The GNU R grainsize package (GitHub) for the free and open software GNU R offers a number of functions tailored to the needs of the sediment laboratory. It allows importing measurement data from the Horiba LA950 and CamSizerXT devices, and contains plotting functions, tools to interpolate between grain size classes and grain size scale conversions. Thus, it is the quasi standard to work with high resolution grain-size data in GNU R. Furthermore, the imported data sets can be analysed and evaluated with additional packages, such as rysgran or G2Sd.
- Rahaman, W., Wittmann, H., von Blanckenburg, F. (2017): Denudation rates and the degree of chemical weathering in the Ganga River basin from ratios of meteoric cosmogenic 10Be to stable 9Be. - Earth and Planetary Science Letters, 469, pp. 156-169. DOI: http://doi.org/10.1016/j.epsl.2017.04.001
- Wittmann, H., von Blanckenburg, F., Mohtadi, M., Christl, M., Bernhardt, A. (2017): The competition between coastal trace metal fluxes and oceanic mixing from the 10Be/9Be ratio: Implications for sedimentary records . - Geophysical Research Letters, 44, 16, pp. 8443-8452. DOI: http://doi.org/10.1002/2017GL074259
- Roettig, C., Kolb, T., Wolf, D., Baumgart, P., Richter, C., Schleicher, A. M., Zöller, L., Faust, D. (2017): Complexity of Quaternary aeolian dynamics (Canary Islands). - Palaeogeography Palaeoclimatology Palaeoecology, 472, pp. 146-162. DOI: http://doi.org/10.1016/j.palaeo.2017.01.039
- Brehme, M., Blöcher, G., Regenspurg, S., Milsch, H., Petrauskas, S., Petrauskas, R., Wolfgramm, M., Huenges, E. (2017): Soft stimulation for solving injectivity problems in a geothermal reservoir, (Proceedings) , 42nd Workshop on Geothermal Reservoir Engineering (Stanford, USA 2017).
- Dietze, M., Dietze, E., Lomax, J., Fuchs, M., Kleber, A., Wells, S. G. (2016): Environmental history recorded in aeolian deposits under stone pavements, Mojave Desert, USA. - Quaternary Research, 85, 1, pp. 4-16. DOI: http://doi.org/10.1016/j.yqres.2015.11.007
- Fuchs, M., Dietze, M., Al-Qudah, K., Lomax, J. (2015): Dating desert pavements – First results from a challenging environmental archive. - Quaternary Geochronology, 30, pp. 342-349. DOI: http://doi.org/10.1016/j.quageo.2015.01.001
- Struck, M., Andermann, C., Hovius, N., Korup, O., Turowski, J., Bista, R., Pandit, H. P., Dahal, R. K. (2015): Monsoonal hillslope processes determine grain size-specific suspended sediment fluxes in a trans-Himalayan river. - Geophysical Research Letters, 42, 7, pp. 2302-2308. DOI: http://doi.org/10.1002/2015GL063360