Call number:
AWI Bio-20-93529
Description / Table of Contents:
The Arctic is considered as a focal region in the ongoing climate change debate. The currently observed and predicted climate warming is particularly pronounced in the high northern latitudes. Rising temperatures in the Arctic cause progressive deepening and duration of permafrost thawing during the arctic summer, creating an ‘active layer’ with high bioavailability of nutrients and labile carbon for microbial consumption. The microbial mineralization of permafrost carbon creates large amounts of greenhouse gases, including carbon dioxide and methane, which can be released to the atmosphere, creating a positive feedback to global warming. However, to date, the microbial communities that drive the overall carbon cycle and specifically methane production in the Arctic are poorly constrained. To assess how these microbial communities will respond to the predicted climate changes, such as an increase in atmospheric and soil temperatures causing increased bioavailability of organic carbon, it is necessary to investigate the current status …
Type of Medium:
Dissertations
Pages:
146 Blätter
,
Illustrationen
URL:
http://www.gbv.de/dms/tib-ub-hannover/827955960.pdf
Language:
English
Note:
Table of content
Abstract
Zusammenfassung
1. Introduction
1.1. Motivation
1.2. Scientific Background
1.2.1. Permafrost in arctic environments
1.2.2. Carbon storage and emission in arctic environments
1.2.3. Methane cycling in arctic environments
1.3. Study Sites
1.3.1. Lena-Delta, Siberia
1.3.2. El’gygytgyn Crater Lake, Chukotka
1.4. Objectives and approach
1.5. Thesis organization
1.6. Summary of the included manuscripts and contribution of the co-authors
1.6.1. Response of methanogenic archaea to Late Pleistocene and Holocene climate changes in the Siberian Arctic
1.6.2. Response of microbial communities to landscape and climatic changes in a terrestrial permafrost sequence of the El’gygytgyn crater, Far East Russian Arctic
1.6.3. Glacial-interglacial microbial community dynamics in Middle Pleistocene sediments in the Lake El’gygytgyn, Far East Russian Arctic
2. Response of methanogenic archaea to Late Pleistocene and Holocene climate changes in the Siberian Arctic
2.1. Abstract
2.2. Introduction
2.3. Materials and Methods
2.3.1. Study site
2.3.2. Permafrost drilling and sample preparation
2.3.3. Sediment properties
2.3.4. Potential methane production rates
2.3.5. Lipid biomarker analysis
2.3.6. Detection of archaeol and isoprenoid GDGTs
2.3.7. Detection of PLFAs and PLELs
2.3.8. DNA extraction and polymerase chain reaction (PCR) amplification
2.3.9. Phylogenetic analysis
2.4. Results and Discussion
2.4.1. Methane profile of the Kurungnakh permafrost sequence
2.4.2. Signals of living microbial communities in the Kurungnakh permafrost sequence
2.4.3. Reconstruction of past microbial communities in the Kurungnakh permafrost sequence
2.4.4. Climate impact on the distribution of microbial communities in the Kurungnakh permafrost sequence
2.4.5. Climatic impact on the composition of methanogenic communities in the Kurungnakh permafrost sequence
2.5. Conclusion
2.6. Acknowledgement
3. Response of microbial communities to landscape and climatic changes in a terrestrial permafrost sequence of the El’gygytgyn crater, Far East Russian Arctic
3.1. Abstract
3.2. Introduction
3.3. Materials and Methods
3.3.1.Study site
3.3.2. Drilling and sample material
3.3.3. Sediment properties
3.3.4. Lipid biomarker analysis
3.3.5. Detection of glycerol dialkyl glycerol tetraethers (GDGTs) and archaeol
3.3.6. Detection of phospholipid fatty acids (PLFA)
3.3.7. Deoxyribonucleic acid (DNA) extraction and amplification
3.3.8. Quantitative PCR analysis of archaeal and bacterial small sub unit (SSU) rRNA genes
3.3.9. Phylogenetic analysis
3.4. Results
3.4.1. TOC-contents
3.4.2. Distribution of glycerol dialkyl glycerol tetraethers (GDGTs) and archaeol
3.4.3. Distribution of phospholipid fatty acids (PLFA)
3.4.4. Composition of archaeol and isoprenoid GDGTs
3.4.5. Quantification of bacterial and archaeal genes
3.4.6. Analysis of methanogenic community fingerprints
3.5. Discussion
3.5.1. Microbial communities in subaquatic deposits
3.5.2. Microbial communities in subaerial deposits
3.5.3. Microbial succession in the Holocene sequence of Lake El’gygytgyn permafrost
3.6.Conclusion
3.7. Acknowledgements
4. Glacial-interglacial microbial community dynamics in Middle Pleistocene sediments in the Lake El’gygytgyn, Far East Russian Arctic
4.1. Abstract
4.2. Introduction
4.3. Materials and Methods
4.3.1. Study site
4.3.2. Drilling and sample preparation
4.3.3. Sediment properties
4.3.4. Lipid biomarker analyses
4.3.5. Deoxyribonucleic acid (DNA) extraction and quantitative polymerase chain reaction (qPCR)
4.3.6. PCR amplification of methanogenic SSU rRNA genes
4.4. Results
4.4.1. Sedimentary TOC and biogenic silica concentration
4.4.2. Quantification of bacterial and archaeal genes
4.4.3. Quantification and composition of lipid biomarkers
4.4.4. Potential methane production
4.4.5. Methanogenic community composition
4.5. Discussion
4.6. Acknowledgements
5. Synthesis
5.1. The reaction of microbial communities to past climatic change in the Arctic
5.2.The response of microbial communities to carbon composition and availability
5.3. Implications from this study for future research
6. Data collection
6.1. Manuscript I: Response of methanogenic archaea to Late Pleistocene and Holocene climate changes in the Siberian Arctic
6.1.1. Sediment properties
6.1.2. Isoprenoid glycerol dialkyl glycerol tetraethers and archaeol
6.1.3. Branched glycerol dialkyl glycerol tetraethers
6.1.4. Phospholipid ester and ether lipids (summary)
6.2. Manuscript II: Response of microbial communities to landscape and climatic changes in a terrestrial permafrost sequence of the El’gygytgyn crater, Far East Russian Arctic
6.2.1. Sediment properties and gene quantifications
6.2.2. Phospholipid fatty acids composition
6.2.3. Isoprenoid glycerol dialkyl glycerol tetraethers and archaeol
6.2.4. Branched glycerol dialkyl glycerol tetraethers
6.3. Manuscript III: Glacial-interglacial microbial community dynamics in Middle Pleistocene sediments in the Lake El’gygytgyn, Far East Russian Arctic
6.3.1. Sediment properties and gene quantifications
6.3.2. Isoprenoid glycerol dialkyl glycerol tetraethers and archaeol
6.3.3. Branched glycerol dialkylglycerol tetraethers
7. References
8. Final thoughts and acknowledgements
9. Curriculum vitae
10.Erklärung
Location:
AWI Reading room
Branch Library:
AWI Library
