Methane cycling in the Greenland ice sheet ecosystem

• Thesis title in Czech: Koloběh metanu v ekosystému grónského ledovce
• Thesis title in English: Methane cycling in the Greenland ice sheet ecosystem
• Key words: metan, koloběh uhlíku, mikrobiální aktivita, stabilní izotopy, ledovcový ekosystém, Grónsko
• English key words: methane, carbon cycling, microbial activity, stable isotopes, glacier ecosystem, Greenland
• Academic year of topic announcement: 2020/2021
• Thesis type: dissertation
• Thesis language: angličtina
• Department: Department of Ecology (31-162)
• Supervisor: Mgr. Marek Stibal, Ph.D.
• Author: hidden - assigned by the advisor
• Date of registration: 08.10.2020
• Date of assignment: 08.10.2020
• Advisors: RNDr. Jakub Trubač, Ph.D.

Preliminary scope of work

Hlavním cílem práce je zjistit prostorovou variabilitu úniku metanu zpod grónského ledovce a původ a stáří uvolňovaného metanu (viz anglický text).

Preliminary scope of work in English

The main aim is to determine the spatial distribution of the CH4 efflux around the Greenland ice sheet and its origin and age. The following specific objectives will be addressed:
1. Is CH4 release from beneath the GrIS ubiquitous or limited to large outlets?
2. What is the age and origin of the released CH4?
3. Is CH4 export related to bed lithology?
4. Is CH4 release correlated with exported microbial assemblages?
The CH4 flux along the west cost of GrIS will be measured using portable high-precision gas measurement technology (OA-ICOS). This will enable to determine whether CH4 flux is limited to the big subglacial outflows and/or lakes or whether subglacial CH4 export occurs all over the ice sheet. Six study regions on the south-north transect of ~2000 km were preselected based on suitable subglacial hydrology and accessibility: Qassimiut (61 °N), Nuuk (64 °N), Kangerlussuaq (67 °N), Ilulissat (69 °N), Upernavik (73 °N), and Qaanaaq (77 °N). To enable comparison and to mitigate melt season progression, the measurements will follow the south-north gradient. At each study region, a transect of 10 to 20 km will be used for direct CH4 measurements. Additionally, meltwater, subglacial sediment and air samples will be collected for subsequent analysis.
Collected CH4 samples will be analysed for stable isotopes (13C/12C and 2H/1H) using gas chromatography-isotope ratio mass spectrometry (GC-IRMS) at Charles University’s stable and radiogenic isotopes facility. This will shed light onto the microbial CH4 production and consumption processes and linked pathways. Filtrates of meltwater will be used for determination of major ions and dissolved nutrient concentrations using ion chromatography and combustion analysis at Charles University’s facilities. These will be then correlated to the measured CH4 flux. To determine the relationship between released CH4 and the exported microorganisms, results of molecular analysis from microbial extracted DNA (qPCR, Illumina sequencing) will be compared to methane release data.