Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Organic geochemical investigation of sources, transport and fate of terrestrial organic matter in the southeast Laptev Sea
Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM). (Örjan Gustafssons research group)
2012 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Permafrost carbon stores have been suggested to react to warming trends with increased terrestrial loading to its coastal waters. Presently, the warming has been seen to be especially high in the East Siberian Arctic and the fate of the major release of terrestrial matter to these coasts is yet to be detailed.

Our work is focused on the East Siberian Shelf (ESS) – which is the largest continental shelf in the world. It receives substantial inputs of terrestrial organic matter both from the large Russian rivers and from eroding coastlines. The largest of its rivers, the Lena, discharges in Buor-Khaya Bay, which is also a hot spot for coastal erosion.

Previous studies of molecular and δ¹3C and Δ¹⁴C composition of terrestrial organic matter received by Arctic coastal waters have suggested a different propensity of different terrestrial source materials towards bacterial degradation. This detailed isotopic and molecular marker survey which is the basis for this thesis reveals clearly distinguished source patterns both between surface water (POC) and sea floor (SOC) as well as with distance away from the sources. The heavy terrestrial dominance over marine/planktonic sources are clearly detected in gradients of high POC and SOC levels, as well as depleted δ13C -OC and high HMW/LMW n-alkane ratios. Furthermore, data suggests that terr-OC was substantially older yet less degraded in the surface sediment than in the surface waters. This unusual vertical degradation trend was only recently found also for the coastal and central East Siberian Sea. It seems that the riverine terr-OC component comprising mainly annual thaw layer surface soil dominates the buoyant surface water POC and is readily degraded. This is in contrast to the coastline-erosion terr-OC which is associated with minerals and therefore ballasted to the sediments where it makes up the key OC component and seems relatively protected from degradation.

The study area of this work is a region with strong terrestrial influence hosting many of the important carbon cycling processes, and data reveal two important OC contributors of different origin, mineral associated coastal erosion matter and riverine borne surface soil matter. These two components may well represent different propensities to contribute to a positive feedback to climate warming by converting OC from coastal and inland permafrost into CO₂.

Place, publisher, year, edition, pages
Frescati, Stockholm: Stockholm University, 2012. , 23 p.
National Category
Climate Research Geosciences, Multidisciplinary Other Earth and Related Environmental Sciences
Research subject
Biogeochemistry; Marine Geoscience; Applied Environmental Science
Identifiers
URN: urn:nbn:se:su:diva-82863OAI: oai:DiVA.org:su-82863DiVA: diva2:572698
Presentation
2012-05-25, Nordenskiöldsalen, Geovetenskapens hus, Svante Arrhenius väg 12, Stockholm, 15:00 (English)
Opponent
Supervisors
Available from: 2013-01-22 Created: 2012-11-28 Last updated: 2013-01-22Bibliographically approved
List of papers
1. Carbon isotopes and lipid biomarker investigation of sources, transport and degradation of terrestrial organic matter in the Buor-Khaya Bay, SE Laptev Sea
Open this publication in new window or tab >>Carbon isotopes and lipid biomarker investigation of sources, transport and degradation of terrestrial organic matter in the Buor-Khaya Bay, SE Laptev Sea
Show others...
2011 (English)In: Biogeosciences, ISSN 1726-4170, E-ISSN 1726-4189, Vol. 8, no 7, 1865-1879 p.Article in journal (Refereed) Published
Abstract [en]

The world's largest continental shelf, the East Siberian Shelf Sea, receives substantial input of terrestrial organic carbon (terr-OC) from both large rivers and erosion of its coastline. Degradation of organic matter from thawing permafrost in the Arctic is likely to increase, potentially creating a positive feedback mechanism to climate warming. This study focuses on the Buor-Khaya Bay (SE Laptev Sea), an area with strong terr-OC input from both coastal erosion and the Lena river. To better understand the fate of this terr-OC, molecular (acyl lipid biomarkers) and isotopic tools (stable carbon and radiocarbon isotopes) have been applied to both particulate organic carbon (POC) in surface water and sedimentary organic carbon (SOC) collected from the underlying surface sediments. Clear gradients in both extent of degradation and differences in source contributions were observed both between surface water POC and surface sediment SOC as well as over the 100 s km investigation scale (about 20 stations). Depleted delta(13)C-OC and high HMW/LMW n-alkane ratios signaled that terr-OC was dominating over marine/planktonic sources. Despite a shallow water column (10-40 m), the isotopic shift between SOC and POC varied systematically from +2 to +5 per mil for delta(13)C and from +300 to +450 for Delta(14)C from the Lena prodelta to the Buor-Khaya Cape. At the same time, the ratio of HMW n-alkanoic acids to HMW n-alkanes as well as HMW n-alkane CPI, both indicative of degradation, were 5-6 times greater in SOC than in POC. This suggests that terr-OC was substantially older yet less degraded in the surface sediment than in the surface waters. This unusual vertical degradation trend was only recently found also for the central East Siberian Sea. Numerical modeling (Monte Carlo simulations) with delta(13)C and Delta(14)C in both POC and SOC was applied to deduce the relative contribution of - plankton OC, surface soil layer OC and yedoma/mineral soil OC. This three end-member dual-carbon-isotopic mixing model suggests quite different scenarios for the POC vs SOC. Surface soil is dominating (63 +/- 10 %) the suspended organic matter in the surface water of SE Laptev Sea. In contrast, the yedoma/mineral soil OC is accounting for 60 +/- 9% of the SOC. We hypothesize that yedoma-OC, associated with mineral-rich matter from coastal erosion is ballasted and thus quickly settles to the bottom. The mineral association may also explain the greater resistance to degradation of this terr-OC component. In contrast, more amorphous humic-like and low-density terr-OC from surface soil and recent vegetation represents a younger but more bioavailable and thus degraded terr-OC component held buoyant in surface water. Hence, these two terr-OC components may represent different propensities to contribute to a positive feedback to climate warming by converting OC from coastal and inland permafrost into CO(2).

National Category
Environmental Sciences Geosciences, Multidisciplinary Ecology
Research subject
Applied Environmental Science
Identifiers
urn:nbn:se:su:diva-66878 (URN)10.5194/bg-8-1865-2011 (DOI)000294153700009 ()
Funder
EU, FP7, Seventh Framework Programme, 220424
Note

authorCount :8

Available from: 2011-12-22 Created: 2011-12-21 Last updated: 2017-12-08Bibliographically approved

Open Access in DiVA

Licentiate thesis Emma Karlsson(719 kB)279 downloads
File information
File name FULLTEXT01.pdfFile size 719 kBChecksum SHA-512
4cb67127e763755771c3770460777c15af4f275e383c176c8b0d1b296c8a089b7207f2052c882c33872d13659eabd210bd0f0534de511ee3f74db8971a148e1b
Type fulltextMimetype application/pdf
Front page licentiate thesis Emma Karlsosn(222 kB)27 downloads
File information
File name COVER01.pdfFile size 222 kBChecksum SHA-512
3e54517a7b03ecc78d783f90545fef0eb7c97644ca3cb0d7a742d0b9a62c4154da8e17cc7fce3222eec143589ecb04e43b4846dfe12fd58c5a5b6b1e46211734
Type coverMimetype application/pdf

Search in DiVA

By author/editor
Karlsson, Emma
By organisation
Department of Applied Environmental Science (ITM)
Climate ResearchGeosciences, MultidisciplinaryOther Earth and Related Environmental Sciences

Search outside of DiVA

GoogleGoogle Scholar
Total: 279 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

urn-nbn

Altmetric score

urn-nbn
Total: 217 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf