degradation at the land-ocean interface George Tanski, Michael - - PowerPoint PPT Presentation

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degradation at the land-ocean interface George Tanski, Michael - - PowerPoint PPT Presentation

Mar 03, 2023 26 likes •289 views

Permafrost carbon release and degradation at the land-ocean interface George Tanski, Michael Fritz, Justine Ramage, Christian Knoblauch, Nicole Couture, and Hugues Lantuit Herschel Island, Yukon, Canada Background of northern landmass of

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Permafrost carbon release and degradation at the land-ocean interface

George Tanski, Michael Fritz, Justine Ramage, Christian Knoblauch, Nicole Couture, and Hugues Lantuit

Herschel Island, Yukon, Canada

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Background

  • f northern landmass
  • f global coasts

km of coastline

Global carbon storage in soils TARNOCAI et al. 2009 (Gt Corg.) George Tanski 1

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Background

  • f the coast are unlithified

Erosion rates up to

Herschel Island, Yukon Coast, Canada George Tanski 2

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Background

Komakuk Beach, Yukon Coast, Canada

  • f the coast are unlithified

Erosion rates up to

George Tanski 3

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Background

Herschel Island, Yukon, Canada Photo: J. WOLTER

  • f the coast are unlithified

Erosion rates up to

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Topic I

Dissolved organic carbon (DOC)

OC ≤ 0.45 µm

Particulate organic carbon (POC) Sediments

release...

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Unglaciated Glaciated

Beaufort Sea (Arctic Ocean)

Herschel Island Study sites Roland Bay Kay Point

Canada

Topic I: Release of DOC from ground ice

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Topic I: Release of DOC from ground ice

Coastal erosion* DOC: ? SOC: 0.04 Gg yr-1 Sediment: 2.66 Gg yr-1 River discharge** DOC: 1.3 Gg yr-1 POC: 2.1 Gg yr-1 Sediment: 127.0 Gg yr-1

George Tanski

* MACDONALD et al. 1998 ** COUTURE 2010

1 Gg = 1012 g = 109 kg = 106 t

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  • Ground ice content and types along the Yukon Coastal Plain

Topic I: Release of DOC from ground ice

A) Ice wedges B) Massive ice beds C) Pore/Non-massive intrasedimental ice C: 26% A+B: 11% 37% ground ice

After COUTURE 2010

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  • Ground ice content and types along the Yukon Coastal Plain

Topic I: Release of DOC from ground ice

A) B) C) A) Ice wedges B) Massive ice beds C) Pore/Non-massive intrasedimental ice C: 26% A+B: 11% 37% ground ice

After COUTURE 2010

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  • Calculation of DOC flux

Topic I: Release of DOC from ground ice

Modified, after COUTURE 2010

DOCflux= n j=1 lj ∗ hj ∗ Rj ∗ DOCstoragej

George Tanski

DOCstorage= n j=1 θj ∗ ρ ∗ DOCconc.j

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Topic I: Release of DOC from ground ice

Coastal erosion** DOC: 0.09-3 Gg yr-1 SOC: 0.04 Gg yr-1 Sediment: 2.66 Gg yr-1 River discharge* DOC: 1.3 Gg yr-1 POC: 2.1 Gg yr-1 Sediment: 127.0 Gg yr-1

George Tanski

* MACDONALD et al. 1998 ** COUTURE 2010

1 Gg = 1012 g = 109 kg = 106 t

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  • Low dissolved organic carbon fluxes from eroding permafrost coasts
  • Western part and Herschel Island are hotspots
  • Mostly fluxes from ice thrust moraine ridges and lacustrine deposits
  • Mostly as POC  DOC/POC ratio of ~1:1000
  • OC input from the Mackenzie dominates the Beaufort Sea
  • But: High bioavailabilty of DOC assumed
  • Recent studies show high bioavailabilty
  • e.g. VONK et al. 2013  DOC loss > 34.0 ± 0.8% within two weeks
  • e.g. HOOD et al. 2009  45% of DOCterr. bioavailable

Topic I: Conclusion

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Topic II

Dissolved organic carbon (DOC)

OC ≤ 0.45 µm

Particulate organic carbon (POC) Sediments

release...

Nutrients (NH4, NO2, NO3)

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Unglaciated Glaciated

Beaufort Sea (Arctic Ocean)

Herschel Island Study site

Canada

Slump D

Topic II: Degradation of organic matter

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Topic II: Degradation of organic matter

Retrogressive thaw slump: „Slump D“ George Tanski 15

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Evolution of „Slump D“

Topic II: Degradation of organic matter

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Vegetation classification of „Slump D“ based on NDVI

Topic II: Degradation of organic matter

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30cm depth Surface/10cm depth

DOC

Topic II: Degradation of organic matter

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Surface/10cm depth 30cm depth

DON

Topic II: Degradation of organic matter

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30cm depth Surface/10cm depth

NH4

Topic II: Degradation of organic matter

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  • 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

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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

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  • PYRN celebratesf its 10th anniversary
  • Just released its long-term strategy until 2018
  • Is seeking to increase the network
  • More involvement of east asian partners planned
  • @ICOP 2016 big young researcher workshop planned
  • ICOP 2016 chance to be part of the new Executive Committee
  • You can apply for travel funding!

PYRN

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  • Improvement of the network
  • Census preparation in progress
  • Meet us at the poster session!
  • Find us online or on facebook!

PYRN

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Herschel Island, Yukon, Canada

Thank you very much for the attention!