Rapid permafrost carbon degradation at the land-ocean-interface
George Tanski, S. Ruttor, H. Lantuit , C. Knoblauch, J. Ramage, B. Radosavljevic, G. Mollenhauer, and M. Fritz
Background
of northern landmass of global coasts
km of coastline
Global carbon storage in soils TARNOCAI et al. 2009 (Gt Corg.)
Background
of the coast are unlithified Erosion rates up to
Coastal erosion and ice contents LANTUIT et al. 2012
Yukon coast, Canada
Non-massive: 26%
Massive: 11%
Ground ice: 37%
After COUTURE 2010
Study area
Study area
Study area
Active thaw slumps RAMAGE et al. (in prep.)
Study area
• Differences in carbon and nitrogen through slumping
• Degradation of organic matter before entering the ocean
• Fate of slump material in the ocean
Objectives
Background
Herschel Island, Yukon, Canada Photo: J. WOLTER
Retrogressive
thaw slump
Topic II: Degradation of organic matter
Retrogressive thaw slump: „Slump D“
Topic II: Degradation of organic matter
Retrogressive thaw slump: „Slump D“
1 Tundra 2 Permafrost 3 Mudpool 4 Slump floor 5 Nearshore
undisturbed
disturbed 1
2
Vegetation classification of „Slump D“ based on NDVI
Background
Background
Organic matter inventory (TOC and DOC)
Tundra Permafrost Mudpool Slump floor Nearshore
Organic matter inventory (TN and DN)
Degradation of organic matter
Degradation of organic matter (d13C, d13C-DOC)
Degradation of organic matter (Nutrients)
Degradation of organic matter (Nutrients)
30cm depth
Surface/10cm depth
NH 4
Topic II: Degradation of organic matter
Surface/10cm depth
30cm depth
DON
Topic II: Degradation of organic matter
Topic II: Fate of organic matter
Marine short core, CTD: Pb-210, TOC, d13Corg., C/N
Topic II: Fate of organic matter CTD
O2: 98.2%, Salinity: 18.9, pH: 8.2 (n = 5, 25.07. – 03.08.)
O2: 99.1%, Salinity: 19.5,
pH: 8.2 (n = 8, 25.07. – 13.08.)
Close to shore Further from shore
O2: 98.6%, Salinity: 27.3, pH: 8.2 (n = 11, 25.07. – 13.08.)
O2: 101.6%, Salinity: 27.3, pH: 8.1 (n = 12, 25.07. – 13.08.)
No DOC and POC
yet, cDOM in
progress and Flouresce
nce
• DOC conc. gradient from permafrost headwall to slump deposits
Degradation of DOC right after thawing
• High ammonium conc. directly after thawing
Indicator for quick depletion of organic material
• Strong degradtion of organic material at the land-ocean interface
Topic II: Conclusion
What are the degradation mechanisms?
What are the degradation patterns of POC?
What happens with permafrost carbon after transport into the ocean?
What are possible impacts on nearshore marine nearshore ecosystem?
How is OC incorporated into local food webs?
Outlook and open questions
