Nanoparticles and particulate matter

In geosciences and environmental research small particles in the sub mm range are important actors. Due to their small size, the particles can be transported over long distances in both water and the atmosphere and they can deeply penetrate organisms. Besides they often play a key role in sorption processes as they have a large surface to volume ratio.

The working group of Applied Geology addresses small particles in different environmental compartments, taking into account both natural and anthropogenic origins.

Nanoparticles/Colloids

The quantitative description of the transport-controlling processes of natural and artificial nanoparticles via the soil zone into aquifers or from the groundwater over the soil zone into the biosphere is still poorly understood. Process understanding through a so-called "bottom-up" approach with the targeted variation of individual parameters, such as surface charge, geometry or density of the nanoparticles, the roughness of the collector (sand grain or fracture surface) and flow velocity variations in the pore space due to the complex fracture network are the subject of current research. Previous work has shown that surface roughness plays a dominant role, especially for <100 nm nanoparticles, and even under "non-favoring" geochemical conditions these nanoparticles can be significantly immobilized in geological systems. Further work focuses on the co-transport of pollutants with such nanoparticles/colloids and especially (a) the reasons for the observed trace element desorption kinetics (sorption or structural incorporation) and (b) the model-technical description of these transport processes.

Project leader: Thorsten Schäfer

AFM measurements roughness measurements on a biotite mineral from the granodiorite top surface using the colloid-probe technique.
Measured snap-in forces, which show a strong attraction in the area of the biotite edges (pH 5, 1 mM NaCl).

Fine dust

Small particles suspended in the atmosphere are most often called particulate matter (PM). Enhanced levels of PM are known to be a severe environmental problem in urban and densely populated regions all over the world. Various adverse effects to human health are known and the particles can influence ecosystems as well as the climate. In our working group the use of biological material (biomonitoring) and simple passive samplers to sample PM is tested. For the biomonitoring both current aspects as well as less known methods are applied. The heavy metal contents in the samples are evaluated by means of (multivariate) statistical methods to detect spatial heterogeneous sources of PM.