Education

A variety of low-cost sensors exist that wait to be exploited for geohydrological applications:
- soil moisture sensors
- scales in python or with arduino
- temperature sensors
- CO2 sensors
and many more.

The broad goal of this thesis is to evaluate to what extent sensors driven from the maker:space are suitable for geohydrologic investigations such as thermal in-situ remediation systems
.
Prospective Tasks
- Establish setups of novel measurements and compare to
- established measurement techniques
- The specifics will be determined jointly
- Visualization and statistical analysis of results and discussion

Desireable Skills
- some experience in python and electronics (raspberry,
- microcontrollers) would be ideal
- Interest in practical work
- Motivated and creative thinking

Supervisor : PhD-student: Anna Burkhardt

The unsaturated zone in the subsurface above the water table plays an important role for water infiltration and contaminant transport (“contaminants of emerging concern” such as PFAS).

The key soil property of a soil responsible for transmitting water is the capillary pressure – saturation relationship. The goal of this M.Sc. thesis is to establish a set of parameters and associated uncertainty estimates for a number of typical porous media used in our laboratory.

These parameters will then be improved input parameters for estimating contaminant mass fluxes to the groundwater and potentially to drinking water wells.
Prospective Tasks:
▪ Familiarize yourself with water flow processes in the unsaturated zone, as well as the concepts and methodology of our measurement setup.
▪ Perform a set of experiments to measure capillary pressure – saturation relationships of soil samples.
▪ Analyze those experiments and fit models for the capillary pressure – relationships in order to obtain a set of parameters including uncertainty estimates.

Desireable Skills:
▪ Experiences in laboratory work is a plus. We are looking for a person with the ambition to work in a soil laboratory.
▪ Ideally some python or other data wrangling skills.

Keywords: Geohydrology, Hydrology, Statistics, Data Analysis, Groundwater Modelling

M.Sc. Topic – Environmental Analytical Chemistry
Per- and polyfluoroalkyl substances (PFAS) pose a serious environmental threat due to their persistence, mobility, and toxicity. Despite increasing regulatory efforts, there is currently a lack of effective forensic tools to trace contamination sources and apply the polluter-pays principle. This master’s thesis aims to develop an innovative compound-specific isotope analysis (CSIA) method for PFAS using high-resolution Orbitrap mass spectrometry (HRMS). The focus will be on establishing reliable analytical protocols for selected PFAS starting with TFA, and potentially with PFBA, PFBS, PFOA and PFOS, with an emphasis on quantifying stable carbon (13C/12C), sulfur (34S/33S/32S) and oxygen (18O/16O) isotope ratios.

The thesis includes the systematic development of Orbitrap-based CSIA methods (optimizing ionization, scan parameters, and fragmentation behavior) for selected PFAS. The ultimate goal is to generate reproducible isotopic “fingerprints” that allow for source attribution dependent on production methods or degradation processes. The results will support environmental forensic investigations, help identify responsible polluters, and contribute to more targeted and effective remediation strategies. The master thesis offers a unique intersection of environmental chemistry, high-resolution mass spectrometry, and applied environmental science.

Prospective Tasks
- Literature review on CSIA, HRMS and the application of HRMS to measure stable isotopes.
- Systematic HRMS-CSIA method development for TFA (+ other compounds) and data evaluation
- Development of Step-by-Step guides to apply the methods
- Visualization of results and discussion

General Information
- The thesis can be co-advised/examined by a different department (e.g., chemistry)

Compound-specific isotope analysis (CSIA) is a promising tool for identifying and differentiating sources of PFAS contamination. Differences in stable isotope ratios, particularly δ13C, δ15N or δ18O or can provide additional information that complement conventional concentration-based and chemical fingerprinting approaches. However, isotope data for PFAS are currently scattered across scientific publications and are often reported using different analytical methods, reference materials, and levels of methodological detail. A structured database is therefore needed to systematically collect, organize, and evaluate available PFAS isotope data.

The aim of this thesis is to develop the basis of a structured reference database for stable isotope signatures of PFAS. Literature data as well as available measurements from the laboratory will be compiled and evaluated.
The thesis will result in a structured and documented PFAS isotope database that can be expanded in future research projects. The database should provide a foundation for comparing newly measured isotope values with existing reference data and ultimately support the application of CSIA for PFAS source differentiation and forensic investigations.

Prospective Tasks
- Identify scientific publications reporting stable isotope ratios of PFAS, compile available data for relevant PFAS, Identify the analytical methods and reference scales used.
- Develop a suitable database structure, define relevant metadata (e.g., supplier, lot number, isotope value, uncertainty, analytical method and literature source), establish standardized terminology and data formats
- Develop graphical representations of PFAS isotope signatures, identify isotope ranges, evaluate patterns between different materials, suppliers or potential sources


Desireable Skills
- Background in environmental chemistry
- Understanding of stable isotope principles (CSIA) is helpful but not mandatory; willingness to learn is essential
- Innovative and critical thinking & scientific curiosity
- Attention to detail and documentation
- Communication Skills

M.Sc. Topic – Water Treatment/Environmental Chemistry
Per- and polyfluoroalkyl substances (PFAS) represent one of the most persistent classes of environmental contaminants. Their exceptional chemical stability makes conventional water treatment technologies largely ineffective. Recent studies suggest that far-UVC irradiation (e.g., 222 nm KrCl excimer lamps) can induce photolytic PFAS degradation, especially for long-chain perfluorocarboxylic acids. However, degradation is often incomplete and leads to the formation of shorter-chain transformation products that remain persistent. In contrast, 172 nm Xe2 excimer lamps provide photons of substantially higher energy, potentially enabling more effective PFAS destruction. Yet, scientific knowledge on their degradation mechanisms, efficiency, and transformation pathways remains extremely limited. Strong light absorption by water, altered radical chemistry, and potentially different reaction pathways make 172 nm irradiation a largely unexplored but promising technology.

This Master thesis will investigate the degradation of PFAS under 172 nm irradiation in a dedicated excimer-lamp reactor system. The work aims to systematically evaluate degradation efficiency, chemical mechanisms, transformation products, and mineralization (fluoride release), thereby laying essential groundwork for future reactive water treatment applications.

Prospective Tasks
- Comprehensive literature review on PFAS photolysis & excimer-lamp technologies
- Experimental design and execution of degradation experiments using a Xe2 172 nm excimer lamp system with systematic investigation of reaction conditions
- Analytical quantification of parent PFAS and transformation products (TPs) using targeted and non-targeted HRMS approach and assessment of mineralization efficiency
- Elucidation of degradation pathways, comparing observed TPs with proposed mechanisms in the literature
- Evaluation of technology potential and limitations for environmental application
- Visualization of results and discussion
- Documentation, visualization, and interpretation of results in a scientific thesis