Offered master thesis
|Impact of Mn on Fe mineralization pathways in wetland soils and sediments|
MOTIVATION: Iron (Fe) is the fourth most abundant element on the earth’s surface. Due to its redox-sensitivity and its sorption capacity for nutrients and contaminants, it plays a particularly important role in the environmental biogeochemistry of wetland soils and sediments.
In soils with a fluctuating water table, the microbial reduction of Fe(III) generates Fe(II). The produced Fe(II) may interact with the remaining solid phase, thus catalyzing the transformation of metastable Fe oxides (e.g. ferrihydrite) to stable minerals such as goethite. Interestingly, previous research has shown that the co-occurrence of manganese (Mn) in such soils appears to trigger the formation of feroxyhyte, a relatively rare Fe oxide that has been largely overlooked in the past. The factors and mechanisms driving the switch to feroxyhyte formation in the presence of Mn remain, however, elusive.
AIM: Using a controlled laboratory experiments and innovative analytical techniques, this project will investigate the impact of Mn on the formation of secondary Fe phases and resolve the specific structural mechanisms that control feroxyhyte formation at high Mn loadings.
WE OFFER individual supervision by enthusiastic researchers and of state-of-the-art approaches for the characterization of aqueous and solid phases (XRD, Mössbauer analysis, SEM, TEM, FTIR). You will become familiar with all practical aspects of science and learn how to design, run, analyse and present experiments that target at your research question.
YOU ARE a highly motivated student with a strong interest in experimental work in the geosciences and with passion for research. Previous experience with analytical and laboratory techniques is an asset, but no prerequisite.
If you are interested or if you need any further information, feel free to contact Dr. Kerstin Hockmann at firstname.lastname@example.org or visit www.kerstinhockmann.com.
Contact: Kerstin Hockmann
|Transport of micro/nano plastic particles in saturated porous media: insights from organic substances in groundwater|
Compared with macroplastics, micro/nano plastic particles in the environment have several unique properties, such as a higher surface to volume ratio leading to increased surface reactivities and stable colloid characteristics. Thus, their unique properties probably make their transport behavior in porous media different from other colloids, such as graphene and TiO2.
Organic substances, like low-molecular-weight organic acids (LMWOAs) and humic acid, is quite common in groundwater and soil solution. LMWOAs can be adsorbed by colloids resulting in changes in surface properties of colloids. Thus, it is reasonable to draw the conclusion that these organic substances will affect the transport of micro/nano plastic particles in porous media. But we do not know the results and extent. Column experiment is a good way to investigate and understand the effects of organic acids on the transport of micro/nano plastics. We can do it together in the future.
In our lab, we have High Performance Liquid Chromatography (HPLC), UV-Vis Spectroscopy, Fluorescence Spectrophotometer and Column experiment equipment, which will do you a great favor in sample measurement. Besides, we also cooperate with other departments to do Zeta potential measurement, Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM). It is an excellent opportunity to develop yourself.
This project is funded by SFB project---CRC 1357 Micro plastic
If you are interested in this research, or you have some questions, don't hesitate to tell me. Email: email@example.com
Contact: Taotao Lu