ECTS
30
Period
Spring semester 2020 (flexible start possible)
Level
Master
Academic term
4th semester
Language of supervision
English
Department
Department of Ecoscience
Faculty
Faculty of Technical Sciences
Location
Risø
Northern peatlands harbor an estimated 2/3 of the global soil organic carbon corresponding to an amount of roughly 50% of the current atmospheric carbon (Dorrepaal et al. 2009). The Arctic accommodates a majority of 800 Gt terrestrial carbon in form of organic matter stored in permafrost (Hugelius et al., 2014; Parmentier et al., 2017). These perennially frozen soils constitute up to 25% of Earth’s surface. Thawing permafrost soils are increasingly susceptible to microbiological decomposition and hence metabolization of terrestrial organic carbon and transformation into the greenhouse gases (Schuur et al., 2015), such as N20, CO2 and CH4. The latter equates 28 CO2 equivalents by its potential to accelerate the atmospheric greenhouse effect compared to CO2 (IPCC, 2014).
Changes in ambient temperature and hydrology within these ecosystems determine the dominance anaerobic versus aerobic soil conditions and eventually favoring microbial CH4 or CO2 respiration and emissions to the atmosphere (Schuur et al. 2015). Hence, laboratory incubations often include various oxygenation and moisture levels to simulate responses of Arctic ecosystems in part to increasing thermal stress. In former incubation experiments, increasing temperature and oxygenation supported higher rates of carbon release, especially in form of CH4 corresponding to a change of microbial community, especially dominated by methanogenic archaea (Mackelprang et al., 2011; Hultman et al., 2015). The intensity of community shifts increased exponentially with temperature above the freezing point (Schostag et al., 2019). Gaps of knowledge on microbial community include the connection between shifts of functional taxonomy and biogenic gas fluxes in dependence of thermal stress as key to understanding and predicting greenhouse gases in the Arctic.
An estimated 20% of Arctic permafrost areas are subject of thermokarsts, caused by melting of belowground ice and consequent collapse of the soil surface (Olefeldt et al. 2016). In 2018, a thermokarst developed into a thermal erosion gully in close vicinity to the Zackenberg Research Station, North-East Greenland, enabling a precise observation and sampling during its progression.
In order to characterize the development of a thermokarst soil microbial community and understand its spatial distribution and taxonomic biodiversity, peaty soil cores of 30cm above and below the ice lens of were taken in August 2018 after the collapse, as well as in September 2019, after a dry and warm summer season, until 90cm depth to also sample still frozen permafrost soils as well.
Scientific questions may include, but are not limited to:
1. The microbial community will depict a depth-specific carbon respiration potential and thermal sensitivity, reflecting natural variations of surface opposing to deeper, possible permanently frozen soil layers.
2. The intensity of respiration can be linked to the moisture of the soil samples with wetter soils depicting a higher methanogenic potential and microbial community.
3. A significant difference in soil respiration can be monitored in thawed permafrost and peat soil samples as opposed to thawing-refreezing cycle set-ups.
Analyzing thermal responses of soil microbiomes: The student will use incubations of Arctic soils at different incubations simultaneously and observe changes in gas fluxes manually with an existing gas chromatography system. These will be put into context with next-generation sequences techniques in order to gain insights into the thermally driven change of microbial composition within the soil samples. Technical development of gas-measurement-automation: The student will develop and test a system to automate gas sampling of the soil incubations at different temperatures and connect these gas samples to an existing gas chromatograph. Development of such systems has been proven crucial for remote field station measurement of gas fluxes, compare “auto chambers”. The progress of development will be put into context with existing manual gas flux measurements of thermally stressed soil incubations.
Expected outcomes of this research will be an improved understanding of microscale processes of bioavailable permafrost and peat soil organic carbon. This will aid stabilizing the scientific base for predicting the fate of carbon stocks in the background of climate change in the Arctic. Furthermore insights on microbial adaptation processes on genetic scales enhance our understanding of polar population genetics and biodiversity as well as life in extreme environments.
The purpose of the thesis is to give the student the opportunity to demonstrate that he/she can independently identify, describe, define, delimit, analyze and solve a relevant substantive, methodological and/or theoretical problem within the program area. The problem that the thesis deals with must be suitable for developing and demonstrating the ability to independently use and produce knowledge using relevant scientific methods as well as the other qualifications developed through the study program.
The Master's thesis is placed on the 4th semester of the MSc program. As the thesis is the final activity of the program, it synthesizes the qualifications and competences that students have gained in the other activities of the program. The thesis is an extremely student-focused activity, regardless of whether the student decide to write their thesis alone or together with another student.
The student is responsible for his/her thesis and for structuring, the work required to reach a satisfactory result. To facilitate his/her work process, the student works with a supervisor who functions as an academic sparring partner.
The supervisor’s task is to help the student resolve the small and large issues that arise during the planning and completion of the thesis; besides what the student should already know based on the teaching they have received and the information available on the study portal. Moreover, the supervisor is the examiner in charge of the oral examination based on the written thesis.
There is restricted time for supervision. Hence, it is important to have an initial discussion and coordination of expectations from both parties.
Literature will be supplied before start of the thesis project.
M. Scheel (PhD student)
M. Mastepanov (senior researcher)
M. A. Jackowicz-Korczynski (researcher)
T. R. Christensen (professor, head of group)
Contact: Maria Scheel
The project proposal has been submitted 10.02.20.