Bachelor and Master Projects

If you would like to do a semester project or a Bachelor or Master Thesis in our group, but there is currently no project listed on this site that meets your interests, contact Tim Eglinton


Master's project: Mineral-associated allochthonous organic matter input into Swiss lakes through flood events

Mineral-​associated allochthonous organic matter input

Background

Flood layers in Swiss lakes transport terrestrial material, containing relatively more allochthonous OM than regular discharge (e.g. Fuentes et al., 2013, Limnologica 43). We observed a trend of more depleted Δ14C towards the top of a major flood in Lake Constance, i.e., finer material contains older OC.

In the same flood layer, fatty acid concentration increased from the bottom to the top half. This could be interpreted as the effect of more effective organic matter stabilization by clay minerals (which are enriched in the finer fraction).

Questions

How does grain size and mineralogy of event layers vary from bottom to top?
How do associated bulk OC isotopes vary?
What is the nature of the organic matter, does it change through the flood layers?
Are there correlations of grain size or mineralogy with OC ages? Are there spatio-temporal trends in these relationships?

Flood layers

Methods

  1. Grain Size measurements, using the laser particle sizer
  2. XRD measurements to identify mineralogy
  3. Bulk O14C, δ13C
  4. Specific-surface area?
  5. C:N ratio?
  6. Lipid extractions

Which Samples?

Either existing cores, that were sampled for a previous campaign, or newly acquired material from Lake Constance, Lake Geneva or Lake Maggiore.

Contact

Benedict Mittelbach ()

Thomas Blattmann ()

Master's project: Locating organic carbon hotspots in marine sediments from the Namibian margin using spatial machine learning algorithms

Locating organic carbon hotspots in marine sediments

Project Background

The Namibian margin stores large amounts of organic carbon in its marine sediments, as a result of the upwelling of cold and nutrient-rich waters to the surface that fuel high marine productivity and sustains a proliferous fishing industry in this margin. High concentrations of organic carbon leads to rapid oxygen consumption and the formation of oxygen minimum zones, enhancing the preservation of fresh organic carbon in marine sediments. However, this preservation could be counteracted by chronic sediment disturbance caused by the widespread bottom trawling activities that occurs along the margin, whose influence hasn’t been accounted yet in this margin.

Project aims

The aim of this project is to locate hotspots of organic carbon content and sites of fresh and reactive organic carbon or aged and refractory organic carbon in marine surface sediments in the Namibian margin. In addition, spatial machine learning techniques will be used to identify the factors that affect the distribution of organic carbon content and its reactivity, in order to predict sites of enhanced organic carbon storage and its vulnerability to anthropogenic disturbance. To achieve these objectives, the student will perform laboratory analyses of marine sediments collected during several cruises, as well as extract data from the Modern Ocean Sediment Archive and Inventory of Carbon (MOSAIC) database. Spatial analyses coupled with machine learning algorithms will be employed to identify the factors that mostly influence the distribution of both organic carbon content and its age along the margin. Depending on the student’s motivation and time-constraints, additional analyses may be performed to better constrain the source of organic carbon in marine sediments.

Through this project, the student will combine a set of valuable skills such as performing analyses in a laboratory, programming, and running spatial analyses. Participation to the ongoing Regional research Graduate Network in Oceanography (RGNO) seminar series is highly recommended to gain a holistic view of the environmental factors that affect the Namibian margin.

Contact

Dr. Sarah Paradis ()
Prof. Dr. Timothy Eglinton ()

Master's project: Carbon transport within an Icelandic river basin

Carbon transport within an Icelandic river basin

Project background

Rivers are important transport agents, transferring organic carbon (OC) from faster cycling terrestrial carbon pools to aquatic sediments, which act as an important carbon sink. However, longitudinal and temporal carbon transport processes across a river basin are not fully understood. In particular, open questions remain regarding OC source and provenance, OC transport mechanisms, as well as corresponding residence times.
The Efri Haukadalsá river catchment in Western Iceland is a small sized river basin allowing a detailed assessment of its carbon cycle. Plant and soil derived organic compounds such as leaf waxes and membrane lipids can be used as biomarkers to determine the provenance of OC and to identify important transport mechanisms within a river basin.

Project goals

Depending on the student’s interest, one or several biomarkers can be chosen for the analysis. The student will investigate biomarker concentrations in soil samples collected during a first sampling campaign in 2021 as well as the biomarker specific isotopic composition (δ13C, δ2H). In addition, the radiocarbon ages of the biomarkers (Δ14C) will be assessed to determine timescales of carbon storage and transport within the river basin.
A selection of measuring techniques such as accelerated mass spectrometry (AMS), gas chromatography (GC-FID) and isotopic ratio mass spectrometry (IRMS) will be available to the student. Within the master’s project, the student might be able to participate in a Haukadalsá lake coring during summer 2022 together with our local collaborator (University of Reykjavik). We are looking for a motivated student enjoying laboratory analysis and is open for potential field work.

Contact

Nora Gallarotti ()

Master's project: Exploring sulfuric acid weathering of kerogen

Master's project

Kerogen exposed on Earth’s surface is subject to decay via oxidation and microbes exerting a fundamental control on the abundance of carbon dioxide and oxygen in Earth’s atmosphere over geologic time. Recent work has shown the importance of sulfuric acid on the decay of minerals including carbonates and silicates. Sulfuric acid commonly evolves from the oxidation of sulfides such as pyrite during weathering processes on Earth’s surface. However, sulfuric acid is a strong oxidant and no examinations have been carried out on the effect of sulfuric acid on kerogen. Results from such a study would provide first-order inight into the biogeochemical relevance of sulfuric acid weathering of kerogen. The student would design laboratory approaches, select samples (with possible fieldwork) to investigate this entirely new area of research.

This project can be executed as a master project.

Contact

Thomas Blattmann ()

Master's project: Tracing carbonate minerals in sediments using radiocarbon

Master's project

Carbonates are minerals that include carbon in their structure. This inorganic form of carbon is ubquitous across Earth’s surface. Carbonates may either be of lithogenic origin such as from limestone or stem from modern precipates via either abiotic or biomineralization pathways. Using radiocarbon, the student will explore an entirely novel way of tracing the source-to-sink fate of carbonates in the environment. Samples from Lake Constance are ready to test this new tool and provide quantitative insight into the sedimentology of carbonates and explore what implications this has for global biogeochemical cycles.

Depending on the candidate, this project can be executed as a semester project, bachelor project, or expanded into a master project.
 

Contact

Thomas Blattmann ()

Master’s project:
Pathways of dissolved organic carbon through terrestrial and aquatic ecosystems in Switzerland

Master’s project: Pathways of dissolved organic carbon

Supervisors: Margot White, Luisa Minich, Timo Rhyner, Timothy Eglinton

Background

Dissolved organic carbon (DOC) is a major component of the global carbon cycle and transfers carbon from soils to groundwater aquifers, rivers, and lakes. On its pathway from the terrestrial to the aquatic domain, DOC composition is altered by various processes including microbial decomposition, particle interactions, and photochemical reactions. Radiocarbon (14C), the long-lived radioactive isotope of carbon, is unique in its potential to quantify the magnitude and pace of carbon exchange among carbon reservoirs. 14C and 13C signatures in bulk DOC as well as in components of the DOC pool help to elucidate the sources of this carbon and to distinguish between slow-cycling and fast-cycling pools.


Description of the Master’s project

The objective of this Master’s project is the identification of specific DOC fractions that help to link DOC reservoirs. The student will work with soil solution samples from Swiss forest sites as well as water samples from Swiss rivers, groundwater, and lakes. The student will test and implement different DOC fractionation approaches (i.e. Solid Phase Extraction, Size Exclusion Chromatography, UV oxidation) to identify fractions that would link DOC across terrestrial and aquatic ecosystems. Isotopic analysis (13C, 14C) will be performed in subsequent DOC fractions. The radiocarbon dating of each fraction will elucidate the age distribution of DOC sources in different DOC pools from the terrestrial to the aquatic domain.

Field work

The student will have the possibility to join field trips across Switzerland to sample water from Swiss river systems, groundwater aquifers, and lakes.

Methodology

• Optical measurements of DOM (e.g., colored and fluorescent properties).
• DOC fractionation using Solid Phase Extraction (SPE), Size Exclusion Chromatography (SEC), and/or UV oxidation

Contact

Margot White ()
Luisa Minich ()
 

mackenzie-river
arctic-ocean

Mackenzie Delta Lake sediments – Records of recent permafrost thaw?

Project background


The Mackenzie River in Northwest Canada is the largest sediment source to the Arctic Ocean. Accelerated warming in the Arctic is expected to lead to increasing organic matter export from thawing permafrost soils with unknown feedbacks to climate and downstream ecosystems.


Project aims


In this project, you will characterize the material transported by the Mackenzie River using delta sediment cores as archives in order to determine whether the materials discharged by the Mackenzie River and its tributaries have responded to recent climatic change, and in particular to seek evidence for mobilization of the vast stores of carbon held in permafrost within the watershed. We aim to collect short sediment cores (<1 m) from ~15 lakes throughout the Mackenzie delta in spring 2021 (tentative dates in early April). Potential analyses include sediment properties (bulk density, grain size distribution, mineral surface area and elemental composition, 143Nd/144Nd isotopes) to elucidate sediment characteristics, as well as bulk elemental and isotopic (% organic carbon, % total nitrogen, δ13C, Δ14C) and molecular organic geochemistry, specifically employing different terrestrial and aquatic biomarkers in order to assess quality, age, origin and degradation of the sedimentary organic matter.

Contact

Dr. Lisa Bröder
Prof. Dr. Timothy Eglinton
 

Project background

One of the major carbon reservoirs on Earth is the carbon stored in soils. However, the turnover time of soil organic carbon (SOC) is still not well constrained. SOC dynamics have been investigated using direct radiocarbon (14C) measurements on different soil fractions that were sampled periodically over several decades. Recently, a novel attempt has been made to constrain turnover times of SOC from the 14C bomb peak in stalagmites. However, so far no direct comparison of the two approaches has been conducted. Yok Balum Cave in Belize is an ideal candidate for such a comparison, since a 14C record exhibiting the bomb peak allows to model SOC pools and turnover times.

Project aims

Samples from a soil depth profile above Yok Balum Cave should be separated into distinct soil fractions using density fractionation at D-USYS. Bulk soils and soil density fractions should be prepared for 14C analysis at D-ERDW and analyzed for 14C using accelerator mass spectrometry (AMS) at the Laboratory for Ion Beam Physics (D-PHYS). Results on the relative proportions and ages of distinct soil fractions should be interpreted with respect to the 14C bomb peak and compared with results from stalagmites. Possibilities to model SOC dynamics using stalagmite data should be explored (in collaboration with modelers from Max Plank Institute for Biogeochemistry).

DownloadMore information (PDF, 337 KB)

Contact

Dr. Carolin Welte

Dr. Marco Griepentrog

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