1 / 29

Methane related microbial activity in sediments of the Beaufort Sea (Arctic Ocean )

Methane related microbial activity in sediments of the Beaufort Sea (Arctic Ocean ). Stefan Krause 1 , Johanna Schweers 1 , Leila Hamdan 2 & Tina Treude 1. 1 Leibniz Institute of Marine Sciences (IFM-GEOMAR), Cluster of Excellence: "The Future Ocean",

nadine
Download Presentation

Methane related microbial activity in sediments of the Beaufort Sea (Arctic Ocean )

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Methanerelatedmicrobialactivity in sediments of theBeaufort Sea (Arctic Ocean) Stefan Krause1, Johanna Schweers1, Leila Hamdan2 & Tina Treude1 1Leibniz Institute of Marine Sciences (IFM-GEOMAR), Cluster of Excellence: "The Future Ocean", Junior Research Group "Marine Geobiology", Kiel, Germany 2Naval Research Laboratory (NRL), Washington, USA

  2. Methanehydrates Methane clathrate, also called methane hydrate or methane ice. Formation and stability of methane hydrates depend on the temperature-pressure regime. Global amount : +/- 10.000 Gt C Arctic amount: unknown Source: Wikipedia Source: Wikipedia Source: IFM-GEOMAR

  3. Sulfate reduction, methanogenesis and methane oxidation in organic-rich, diffusive sediments Sulfate reduction (SR) 2 CH2O + SO42-2 HCO3- + H2S Methanogenesis (MG) 4 H2 + CO2 CH4 + 2 H2O 4 CH3COOHCH4 + 3 CO2 + 2 H2O AOM and SR within the methane-sulfate transition zone CH4 + SO42- HCO3- + HS-+ H2O Kattegat and Skagerrak sediments (Denmark), (Iversen& Jørgensen1985)

  4. Microbial and biogeochemicalreactions at methaneseeps atmosphere water column Aerobic oxidation of methaneCH4 + 2O2 CO2 + 2H2O SO42- NO3- O2 oxygenated sediment Sulfide oxidationH2S + 2O2 SO42- + 2 H+5H2S + 8NO3- 5SO42- + 4N2 + 4H2O + 2H+ H2S reduced sediment Anaerobic oxidation of methane (AOM)CH4 + SO42- HCO3- + HS- + H2O CH4 CaCO3 CH4 hydrate Microbial methane filter in marine systems

  5. Influence of temperatureincrease on microbialactivity Group Range Optimum Psychrophiles -10 – 20°C 10 – 15°C Mesophiles 10 – 50°C 25 – 38°C Thermophiles 40 – 70°C 55 – 65°C Hyperthermophiles 65 – 110°C 85 – 100°C Source: www.bmb.leeds.ac.uk/.../temperature.jpg Microbial methane filter in marine systems

  6. Field study Barrow PC12 PC13 Source: J. Greinert Survey: Three Transects (20 to 2000 m) Piston corer + Multicorer Source: Google Earth

  7. Central Questions • Objectives of the cruise: • What controls methane emissions to the atmosphere? • How will degradation and emission rates vary in response to climate change? • OurTasks: • Characterization of methanerelatedmicrobiological and biogeochemical • processes in sediments of the Beaufort Sea (Arctic Ocean) • Response of microbialmethanogenesis on temperatureincreases

  8. Results Characterization of methanerelatedmicrobiological and biogeochemicalprocesses in sediments of the Beaufort Sea (Arctic Ocean)

  9. Results SR – Sulfate reduction AOM – Anaerobicoxidation of methane MG- Methanogenesis Piston Core 12, waterdepth 342 m SR Zone sedimentdepth (cmbsf) AOM Zone MG Zone

  10. Results In vitro Methanogenesis SR Zone AOM Zone sedimentdepth (cmbsf) MG Zone

  11. Results In vitro Methanogenesis SR Zone AOM Zone sedimentdepth (cmbsf) MG Zone

  12. Methanogenesis and sulfatereduction Methanogenesis (MG) 4 H2 + CO2  CH4 + 2 H2O Reverse methanogenesis (AOM) CH4 + 3 H2O  HCO3- + H+ + 4 H2 2-bromoethanesulfonate (BES) - inhibitor of MG and AOM Anaerobic oxidation of methane (AOM) with sulfate reduction (SR)CH4 + SO42- HCO3- + HS- + H2O Molybdate (Mo) –inhibitor of sulfatereduction

  13. Results Sulfate reductionactivity in sedimentsfromthemethanogeniczone–inhibitionexperimentswithmolybdate SR Zone AOM Zone sedimentdepth (cmbsf) MG Zone Incubation in methanogen medium [SO42-]: 500 µM [CH4]: saturated (~1.3 mM) Temperature: 13°C

  14. Results Sulfate reductionactivity in sedimentsfromthemethanogeniczone–inhibitionexperimentswithmolybdate SR Zone AOM Zone sedimentdepth (cmbsf) MG Zone Incubation in methanogen medium [SO42-]: 500 µM [CH4]: saturated (~1.3 mM) Temperature: 13°C

  15. Results AOM activity in sedimentsfromthemethanogeniczone–inhibitionexperimentswithmolybdate SR Zone AOM Zone sedimentdepth (cmbsf) MG Zone Incubation in methanogen medium [SO42-]: 500 µM [CH4]: saturated (~1.3 mM) Temperature: 13°C

  16. Results AOM activity in sedimentsfromthemethanogeniczone–inhibitionexperimentswithmolybdate SR Zone AOM Zone sedimentdepth (cmbsf) MG Zone Incubation in methanogen medium [SO42-]: 500 µM [CH4]: saturated (~1.3 mM) Temperature: 13°C

  17. Results Sulfate reductionactivity in sedimentsfromthemethanogenic Zone –inhibitionexperimentswith BES (methanogen/AOMinhibitor) SR Zone AOM Zone sedimentdepth (cmbsf) MG Zone Incubation in methanogen medium [SO42-]: 500 µM [CH4]: saturated (~1.3 mM) Temperature: 13°C

  18. Results Sulfate reductionactivity in sedimentsfromthemethanogenic Zone –inhibitionexperimentswith BES (methanogen/AOMinhibitor) SR Zone AOM Zone sedimentdepth (cmbsf) MG Zone Incubation in methanogen medium [SO42-]: 500 µM [CH4]: saturated (~1.3 mM) Temperature: 13°C

  19. Results Activesulfatereduction in the MG-zone Where doesthesulfatecomefrom? Possibleexplanation: Barite BaSO4 Ba2+ + SO42-

  20. First indications of barite/AOM coupling from Benguela Upwelling Region: Riedinger et al. 2006, EPSL, 241 BaSO4 Ba2+ + SO42- Barium

  21. Results Piston Core 12, waterdepth 342 m sedimentdepth (cmbsf) Average seawater concentration of Ba in Arctic Ocean (shelf regions):20-170 nM (Guay & Falkner 1996)

  22. Results Piston Core 13, waterdepth 280 m sedimentdepth (cmbsf)

  23. Results Response of microbialmethanogenesis on temperatureincreases

  24. Results In vitromethanogenesisrates

  25. Results In vitromethanogenesisrates

  26. Results In vitromethanogenesisrates

  27. Conclusions We confirmed the activity of AOM in Arctic methane-rich sediments. The process will most likely play a key role in controlling methane fluxes from the seafloor into the water column in Global Warming scenarios. Barite may represent an additional sulfate source in Arctic sediments (or generally below productive water columns) enabling SR (and possibly AOM) in the predominantly methanogenic zone, i.e., below the penetration depth of seawater sulfate. Methanogenesisgenerallyincreasedwithtemperatureriserevealing a physiologybehaviour (optimumaround 25°C). In case of a temperatureincrease of 1-2°C weexpect an increase in methaneproduction of 50-120% in sedimenttypessampledhere.

  28. Acknowledgements: Fundingof Tina Treude‘sresearchgroup was providedby: German Research Foundation (DFG) via the Cluster of Excellence "The Future Ocean" Beaufort Sea Expedition: On-board sampling:Rick Coffin (NRL, US) Scientific PartyCrew of USCGC Polar Sea Microbial turnover rates (lab of Tina Treude): Geochemical analyzes: Geochemical Lab Hamdan/Coffin (NRL, US)Regina Suhrberg (IFM-GEOMAR)

  29. Thankyouforyourattention

More Related