ИСТИНА

• Охват: Международная
• Даты проведения: 2013
• Место проведения: GEOMAR Helmholtz Centre for Ocean Research Kiel, Germany, Germany
• Число участников: 100
• Число докладчиков: 60
• Описание конференции:

  Page 1/3 http://www.cost-pergamon.eu Monday 4 November 2013 18:30 21:00 18:30 20:00 Tuesday 5 November 2013 08:45 08:45 09:30 09:30 09:50 09:50 10:10 10:10 10:30 10:30 10:50 10:50 11:10 11:10 11:30 11:30 11:50 Workgroup C2 11:50 12:10 12:10 12:30 12:30 12:50 12:50 13:10 13:10 14:15 Lunch 14:15 14:35 14:35 14:55 14:55 15:20 15:20 15:40 15:40 16:00 16:00 16:20 16:20 16:40 16:40 17:00 17:00 17:20 17:20 18:00 18:00 19:00 Location: GEOMAR, Wischhofstrasse 1-3; 24148 Kiel, Germany (Eastshore Building) Catering during the meeting: Coffee and lunch will be provided during the meeting & Icebreaker Joined Dinner: Please register at GEOMAR if you want to join the dinner (40EUR/person) Venue of Dinner: Kieler Brauerai; Alter Markt 9; 24103 Kiel http://www.kieler-brauerei.de/eng/ Isotopic analysis of Arctic methane sources – measurements from the ground to tropopause Arctic carbon storage and greenhouse gas exchange – a measurement based integrated assessment of two c Torben Christensen oupled terrestrial and marine ecosystems Rebecca Fisher Discussion Discussion Relative importance of lake methane emissions in a subarctic peatland landscape, Northern Sweden, depends on spring ice thaw Work Group B2 Welcome and opening of the symposium Presentation of PERGAMON working groups (Jens Greinert) Graham Westbrook Tina Treude Gregor Rehder Atmosphere: Jérôme Chapellaz Coffee & poster session Atmosphere: Jérôme Chapellaz Terrestrial: Patrick Crill Bus transfere from GEOMAR to the hotel Philippe Bousquet Methane budget of the past 30 years : from global to Arctic K v. Huissteden & Budishchev How good are wetland methane flux process models in predicting fluxes? PERGAMON meeting: 5-7 November 2013 PERGAMON Final Symposium COST Action ES0902 PERGAMON 8th and final Management Committee Meeting Ice Breaker in the Aquarium (GEOMAR Westshore Building) PERGAMON meeting: 5-7 November 2013 Registration Aquarium (GEOMAR Westshore Building) Registration Foyer Bus transfere from the hotel to GEOMAR (Eastshore Building) Mathilde Jammet Brett Thornton et al. Energy input to subarctic lakes and subsequent methane ebullition Work Group A Overview & Ocean-warming-induced methane release from Arctic continental margins where permafrost is absent Work Group B1 Symposiums Dinner (by registration only); Kieler Brauerei Coffee & poster session Patrick Crill Workgroup C1 Jan Klerkx Workgroup D Philipe Bousquet Thorsten Sachs Airborne measurements of methane fluxes in the Arctic (AIRMETH) Dalsoeren/Lund-Myhre Reproducing and understanding methane evolution over the last decades. Results from the GAME project Frans-Jan Parmentier et al. Methane emissions in the Arctic. Can we see an influence of sea ice decline? Land-atmosphere methane fluxes from an arctic floodplain and its adjacent Benjamin Runkle polygonal tundra landscape Page 2/3 Wednesday 6 November 2013 08:45 09:20 09:40 09:40 10:00 10:00 10:20 10:20 10:40 10:40 11:00 11:00 11:20 11:20 11:40 11:40 12:00 Water column stratification and methanotrophy in Svalbard 12:00 12:20 12:20 12:40 12:40 13:00 12:40 13:30 13:00 14:00 14:00 14:20 John Pohlman 14:20 14:40 Latest results from a repeated Lena survey 14:40 15:00 15:00 15:20 15:20 15:40 15:40 16:00 16:00 16:20 16:30 16:30 19:00 19:00 Thursday 7 November 2013 08:45 09:20 09:40 09:40 10:00 10:00 10:20 10:20 10:40 10:40 11:00 11:00 11:20 11:20 11:40 11:40 12:00 12:00 12:20 Héctor Marín-Moreno 12:20 12:40 ??? 12:40 13:00 13:10 14:00 14:00 14:20 14:20 14:40 14:40 15:00 15:00 15:30 15:30 15:45 Closing of the meeting 15:45 17:00 Farewell drinks 17:00 Methane blowout in the North Sea: A natural laboratory to study the adaptation of Philipp Wilfert methanotrophic microorganisms Marine sediment: Helge Niemann Georgy Cherkachov Russian Arctic Ocean Ground Reference of Entire Arctic Ocean Satellite Methane Observations Giuliana Panieri Ira Leifer et al. Frederick & Buffet Taliks in relict submarine permafrost and methane hydrate deposits: Pathways for gas escape under present and future conditions Jürgen Mienert Bus transfere from the hotel to GEOMAR Celia Sapart Using isotopes to understand methane formation, removal and transport in the East Siberian Arctic Shelf Vladimir Samarkin Methane production, oxidation and emission in the Laptev Sea Shelf Hydroacoustic quantification of free-gas venting offshore Svalbard, Arctic: Changes in space and time Ben Phrampus etal Marine subbotom and gas hydrates: Jens Greinert Coffee & poster session Lunch Mario Veloso Niko Finke Methane production in marine sea ice of the Chukchi Sea, Barrow Alaska Methane Fluxes from the Western Arctic Ocean: No Evidence for an Arctic Methane Catastrophe Arctic margins, subbottom gas hydrates and leaking methane Discussion Atmospheric methane flux from a methane seep field south of the Dogger Bank, Dutch North Sea Effect of lake level variation on methane dynamics in the sediment of Lake Lina Tyroller Lungern, Switzerland Bus transfere from GEOMAR to the hotel MC meeting (only for MC members) Bus transfere from the hotel to GEOMAR Susan Mau et al Press conference Lunch Coffee & poster session Marine sediment: Helge Niemann Coffee & poster session Philip Steeb Record of methane emissions from the West Svalbard continental margin during the last 16,000 years: results from benthic foraminifera Bus transfere from GEOMAR to the hotel Carolyn Ruppel et al. Paul Overduin Subsea permafrost degradation and inferred methane release in shallow coastal water of the Central Laptev Sea The response of methane hydrate beneath the seabed offshore Svalbard to ocean warming during the next three centuries Terrestrial: Patrick Crill Discussion Discussion Evidence from the joint analysis of a range of types of seismic data for the stratigraphic, structural and thermodynamic controls on the presence of free gas and hydrate beneath the seabed, offshore west Spitsbergen Graham Westbrook Dave Archer (video talk scheduled for 8:40am Chicago time) Tonya DelSontro High resolution CH4 emissions and dissolved CH4 measurements elucidate surface gas exchange processes in Toolik Lake, Arctic Alaska Assessing the linkages between seafloor methane seeps and gas hydrate Carolyn Graves offshore western Svalbard Lea Steinle High temporal variablity of methanotrophic communities offshore Svalbard Ingeborg Bussmann Marine water column: Gregor Rehder / Tina Treude Bus transfere from GEOMAR to the hotel Alaskan Beaufort Sea Heat Flow and Ocean Temperature Analysis: Implications for Stability of Climate-Sensitive Continental Slope Gas Hydrates PERGAMON meeting: 5-7 November 2013 A two-dimensional model of the methane cycle on the Siberian continental shelf and slope Discussion Discussin Efficiency of the benthic microbial methane filter beyond steady-state conditions Discussion Page 3/3 WIFI will be available. Working Groups WG-A: WG-leader Jürgen Mienert, Graham Westbrook WG B1: WG-leader Tina Treude, Helge Niemann WG B2: WG-leader Gregor Rehder, Oliver Schmale Methane fluxes from the sea/lake-floor into the atmosphere WG C1: WG-leader Thomas Friborg, Patrick Crill, WG C2: WG-leader Philippe Bousquet, Jérôme Chappellaz WG D: WG-leader Jan Klerkx Data compilation, integration and organization of data distribution among the scientific community Methane fluxes from the terrestrial environment (wetlands, tundra, Arctic-lakes) Atmospheric methane monitoring and global implications for current and future Arctic warming Biogeochemical processes in the shallow sub-seafloor and at the sediment-water interface around seep sites Methane formation, transport and accumulation in terrestrial and marine sediments and permafrost PERGAMON meeting: 5-7 November 2013 PERGAMON meeting: 5-7 November 2013; GEOMAR, Kiel, Germany 1 Talks PERGAMON meeting: 5-7 November 2013; GEOMAR, Kiel, Germany 2 Thirty years of methane sources and sinks: from global to the Arctic P.Bousquet1, S.Kirschke1, P.Ciais1, M.Saunois1, J.G.Canadell2, E.J.Dlugokencky3, P.Bergamaschi4, D.Bergmann5, D.R.Blake6, L.Bruhwiler3, P.Cameron-Smith5, S.Castaldi7,8, F.Chevallier1, L.Feng9, A.Fraser9, P.J.Fraser15, M.Heimann10, E.L.Hodson11, S.Houweling12,13, B.Josse14, P.B.Krummel15, J.-F.Lamarque16, R.L.Langenfelds15, C. Le Quéré17, V.Naik18, S.O’Doherty19, P.I.Palmer9, I.Pison1, D.Plummer20, B.Poulter1, R.G.Prinn21, M.Rigby22, B.Ringeval13,23,24, M.Santini8, M.Schmidt1, D.T.Shindell25, I.J.Simpson6, R.Spahni26, P.Steele15, S.A.Strode27,28, K.Sudo29, S.Szopa1, G.R. van der Werf30, A.Voulgarakis25,31, M.van Weele32, R.F.Weiss33, J.E.Williams32, G.Zeng34 1LSCE-CEA-UVSQ-CNRS France, 2Global Carbon Project, CSIRO Marine and Atmospheric Research, Australia, 3NOAA ESRL, USA 3Institute for Environment and Sustainability, 4Joint Research Centre, Italy, 5Lawrence Livermore National Laboratory, USA, 6University of California Irvine, USA, 7Department of Environmental Sciences, Second University of Naples, Italy, 8Centro euro- Mediterraneo per i Cambiamenti Climatici CMCC, Lecce, Italy, 9School of Geosciences, University of Edinburgh, UK, 10MPI Biogeochemistry, Germany, 11Swiss Federal Research Institute WSL, Switzerland, 12SRON, Netherlands institute for space research, The Netherlands, 13Institue for Marine and Atmospheric research Utrecht, The Netherlands, 14Météo France, France, 15Centre for Australian Weather and Climate Research/CSIRO Marine and Atmospheric Research, Aspendale, Victoria, Australia, 16NCAR, USA, 17Tyndall Centre for Climate Change Research, UK, 18UCAR/GFDL, USA, 19University of Bristol, UK, 20CCCma, Environment Canada, 21Massachusetts Institute of Technology, USA, 22School of Chemistry, University of Bristol, Bristol, UK, 23IMAU, Utrecht University, The Netherlands, 24Department of Systems Ecology, VU University Amsterdam, The Netherlands, 25NASA GISS, USA, 26University of Bern, Switzerland, 27NASA GSFC, USA, 28Universities Space Research Association, USA, 29Graduate School of Environmental Studies, Nagoya University Furo-cho, Japan, 30VU University, The Netherlands, 31Department of Physics, Imperial College, London, UK, 32Royal Netherlands Meteorological Institute (KNMI), The Netherlands, 33Scripps Institution of Oceanography, USA 34National Institute of Water and Atmospheric Research, New Zealand. Direct measurements of atmospheric methane began in 1978, reached global coverage after 1983, and now include a large variety of observations: in-situ samples collected regularly at the surface or with aircrafts, continuous measurements at the surface or in the low troposphere with tall towers, remotely-sensed atmospheric columns retrieved from the surface or from space since 2003. Although sources and sinks of methane are identified, large uncertainties remain in their spatio-temporal quantification. Here, we present a synthesis of methane emissions and sinks during the past thirty years using an integrated approach to combine: atmospheric measurements, chemistry-transport models, ecosystem models, emission inventories, and climate-chemistry models. Decadal budgets suggest a possible overestimation of total natural emissions by ecosystem models and data-driven approaches. As remaining uncertainties on emission trends do not allow definitive conclusions, emission scenarios are proposed to explain interannual variability of atmospheric methane since 1985. Decreasing to stable fossil fuel emissions combined with stable to increasing microbial emissions is a plausible explanation for the observed stabilization of methane from 1999-2006. Higher emissions from natural wetlands and fossil fuels, with an uncertain relative contribution, likely account for the renewed global increase after 2006. Finally, the projection of this global budget for the Arctic regions is presented and commented. PERGAMON meeting: 5-7 November 2013; GEOMAR, Kiel, Germany 3 Methane emissions in the Arctic. Can we see an influence of sea ice decline? Frans-Jan W. Parmentier, Torben R. Christensen, Wenxin Zhang and Paul Miller Department of Physical Geography and Ecosystem Science, Lund University, Sweden In the past few decades, sea ice extent in the Arctic has seen a dramatic decline, reaching levels two times lower than those observed during the 1980's. This decline in sea ice has led to a large change in surface albedo, and thus the energy budget of the Arctic. Although the specific impact of these albedo changes on the amplified warming in the Arctic is getting clearer and clearer, the additional step of attributing changes in Arctic greenhouse gas exchange to sea ice decline remains understudied. Evidence is mounting, however, that sea ice not only has direct effects on oceanic greenhouse gas exchange, but acts further through teleconnections with the land. In this talk, the effect of sea ice decline on methane emissions will be discussed in particular, with a focus on Arctic wetlands and the potential for increased emissions from subsea-permafrost. Reproducing and understanding methane evolution over the last decades. Results from the GAME project Stig Dalsøren1, Cathrine Lund Myhre2, Gunnar Myhre1 and Ivar Isaksen1 1CICERO, Center for International Climate and Environmental Research Oslo, Norway 2 NILU, Norwegian Institute for Air Research, Kjeller, Norway Results from the GAME project will be presented. One goal in GAME is to understand how emissions in different regions, transport and chemical processes contribute to observed changes in atmospheric methane distribution the last 40 years. The work is a combination of new measurements, analysis of existing and ongoing methane observations, and Chemical Transport Modelling (CTM). A particular focus is on the huge Arctic methane reservoirs with an aim to identify the geographical locations and seasonality of these sources. The Oslo CTM3 model is used to calculate distribution and changes over the last 40 years. The studies include evaluation of different methane sources and source regions, and chemical processes affecting OH distribution and changes, including changes in anthropogenic and natural emissions from different sources. Currently two simulations for the period 1970-2010 are running: One with changes in emission fluxes of methane and all other relevant components affecting methane, and one with fixed methane concentration to quantify how the other components affect the chemical loss of methane. The observed interannual variability, seasonality and absolute levels are reasonably captured by the model. The comparisons made so far look promising. Further analysis of methane tracers and isotope measurements will therefore also focus on finding the major factors driving the methane changes. Examples will be shown in the presentation. PERGAMON meeting: 5-7 November 2013; GEOMAR, Kiel, Germany 4 Isotopic analysis of Arctic methane sources – measurements from the ground to tropopause R.E. Fisher, J.L. France, D. Lowry, M. Lanoisellé and E.G. Nisbet Dept. of Earth Sciences, Royal Holloway University of London, Egham, Surrey, TW20 0EX, United Kingdom Isotopic measurements of methane can provide a constraint on global and regional methane emission models. Methane δ13C has been analysed in air samples from the European Arctic at a range of spatial scales, from chambers to aircraft measurements to identify the isotopic signature of emissions to the atmosphere. Isotopic source signatures of wetland emissions vary across different types of wetland and with temperature and need to be studied in more detail to refine the signatures used in models. The isotopic signature of methane that has built up in chambers at Sodankylä (Finland) and Abisko (Sweden) has been measured, to investigate the causes of heterogeneity in the signature of emissions across the sites. Air samples have also been collected from low height (0.3 and 3m) over wetlands during 24-hour periods to measure daily variations in methane concentration and δ13C. Keeling plots, of methane δ13C against the reciprocal of methane mixing ratio have been plotted to identify the signature of emissions. In July 2012 and August and September 2013 aircraft campaigns took place above northern Scandinavia as part of the NERC funded MAMM project. Samples collected over the wetlands of Northern Scandinavia identify the mixed wetland isotopic signature. This was -71.6 ± 0.4‰ in the August 2013 campaign. Shipboard and low level flights over the west coast of Svalbard have also been carried out to investigate marine sources of methane. Some of the aircraft samples have more remote footprints, as identified using the Met Office NAME particle dispersion model. Samples with a footprint over NE Russia also show the dominance of a biogenic methane source (-70 ± 2 ‰) in summer. Air samples are collected regularly at the Pallas Sammaltunturi and Zeppelin stations and identify seasonal variations in the isotopic composition of regional methane emissions. PERGAMON meeting: 5-7 November 2013; GEOMAR, Kiel, Germany 5 Airborne measurements of methane fluxes in the Arctic (AIRMETH) Torsten Sachs 1 , Andrei Serafimovich 1 , Stefan Metzger 2,3 , Katrin Kohnert 1 and Jörg Hartmann 4 1 GFZ German Research Centre for Geosciences, Potsdam, Germany 2 National Ecological Observatory Network, Boulder, Colorado, USA 3 University of Colorado, Boulder, Colorado, USA 4 Alfred Wegener Institut – Helmholtz Zentrum für Polar-und Meeresforschung, Bremerhaven, Germany One of the most pressing questions with regard to climate feedback processes in a warming Arctic is the regional-scale methane release from Arctic permafrost areas. The Airborne Measurements of Methane Fluxes (AIRMETH) campaigns are designed to quantitatively and spatially explicitly address this question. Groundbased eddy covariance (EC) measurements provide continuous in-situ observations of the surface-atmosphere exchange of methane. However, these observations are rare in the Arctic permafrost zone and site selection is bound by logistical constraints among others. Consequently, these observations cover only small areas that are not necessarily representative of the region of interest. Airborne measurements can overcome this limitation by covering distances of hundreds of kilometers over time periods of a few hours. Here, we present the potential of environmental response functions (ERFs) for quantitatively linking methane flux observations in the atmospheric surface layer to meteorological and biophysical drivers in the flux footprints. For this purpose thousands of kilometers of AIRMETH data across the Alaskan North Slope are utilized, with the aim to extrapolate the airborne EC methane flux observations to the entire North Slope. The data were collected aboard the research aircraft POLAR 5, using its turbulence nose boom and fast response methane and meteorological sensors. After thorough data pre-processing, Reynolds averaging is used to derive spatially integrated fluxes. To increase spatial resolution and to derive ERFs, we then use wavelet transforms of the original high-frequency data. This enables much improved spatial discretization of the flux observations, and the quantification of continuous and biophysically relevant land cover properties in the flux footprint of each observation. A machine learning technique is then employed to extract and quantify the functional relationships between the methane flux observations and the meteorological and biophysical drivers in the flux footprints. Lastly, the resulting ERFs are used to extrapolate the methane release over spatio-temporally explicit grids of the Alaskan North Slope. PERGAMON meeting: 5-7 November 2013; GEOMAR, Kiel, Germany 6 Arctic carbon storage and greenhouse gas exchange – a measurement based integrated assessment of two coupled terrestrial and marine ecosystems Torben R. Christensen1,2, Magnus Lund1,3, Mikhail Mastepanov1, Søren Rysgaard2,3,4Mikkel P. Tamstorf3, Mikael K. Sejr3, Thomas Juul Pedersen2 1. Department of Physical Geography and Ecosystem Sciences, Lund University, Lund, Sweden 2. Greenland Climate Research Centre, Greenland Institute for Natural Resources, Nuuk,Greenland 3. Arctic Research Centre, Aarhus University, Århus, Denmark 4. CEOS, University of Manitoba, Winnipeg, Canada Arctic organic carbon storage has seen increased attention in recent years due to large amounts and potential of releases from both terrestrial/freshwater and marine ecosystems with implications for associated feedback mechanisms in the climate system. Our knowledge about the exact scale and sensitivity for a phase-change of these carbon stocks are, however, limited. Important synthesis processes have led to compilation of the published information on carbon cycling both in a modeling and a measurement context. Recently connections between ocean and land based processes have been explored too. There is, however, a lack of reference sites from where full measurement based data are available documenting the carbon stocks and fluxes at the catchment scale including both terrestrial, limnic and marine components. Catchment scale carbon budgets have been estimated for subarctic environments. Here we extend such budgets making use of the extensive monitoring over the past few years under the auspices of the Greenland Ecosystem Monitoring (GEM) program to arrive at purely measurement based estimates for the C stocks and fluxes in combined terrestrial/freshwater and marine ecosystems. We do this for a subarctic and a high arctic setting, respectively, in Greenland. A fundamental question is how much of this organic carbon that is produced and where along this sequence of linked ecosystem processes the most important interactions with the atmosphere takes place. The answer to this question will vary in time and the temporal aspects of the atmospheric exchanges are an important feature needed for a coherent understanding of arctic ecosystem interactions with climate. Hence, it puts pressure on the time-resolution and continuity of measurements in this complex set of different ecosystems and the degree of challenge this represents also vary between systems. With their upstream catchments Greenlandic terrestrial catchmentfjord ecosystems may form good micro- or mesocosm systems to study as model areas that are relevant for large scale understanding also. We review here the availability of data to provide such a mass balance and also the sensitivity of the individual components to changing climatic conditions. We will as such also point at gaps in our measurement based understanding of these important complex ecosystems. PERGAMON meeting: 5-7 November 2013; GEOMAR, Kiel, Germany 7 How good are wetland methane flux process models in predicting fluxes? J. van Huissteden, A. Budishchev, Y. Mi VU University, Faculty of Earth and Life Sciences, Earth Science Department, De Boelelaan 1085, 1081HV Amsterdam, e-mail j.v.huissteden@vu.nl Development of process models of methane emission started approximately twenty years ago. These models have been used to assess the effects of climate change on wetland methane emission, to upscale fluxes from spatially restricted measurement data to larger areas, or to fill gaps in discontinuous time series of measurement data. However, when compared with measurement data the models show usually significant discrepancies between data and modelled fluxes. In particular short-term temporal variations of the data are poorly reproduced. These discrepancies may have several causes. There are two issues on the data side. The data consist of either chamber flux measurements or eddy covariance data, the latter have become only recently available on a larger scale. Both data types differ strongly in measurement principle, spatial and temporal scale of the data. The models are usually validated on chamber flux measurements which tend to be noisy and show a high spatial variability, even within uniform vegetation/soil units. Model testing on eddy covariance data has only recently been accomplished. On the side of the models there are issues with respect the correct representation of processes of methane production and transport. However the more complex models do not perform necessarily better than the simpler ones. Tests of models with different structure do not generate large differences in performance. Another cause of discrepancy my be the lack of sufficiently precise soil and vegetation data that are input to the models. We performed several experiments with the PEATLAND-VU wetland soil CO2 and CH4 model, using data from a northern Siberian permafrost wetland (Kytalyk reserve). We tested the model performance of CH4 fluxes both with respect to chamber and eddy covariance data. Also tests were performed with respect tot model structure by including submodels of primary organic matter production of different complexity. The tests have shown that the model can reproduce yearly variation in the magnitude of fluxes correctly, but that smaller scale temporal variations in flux are less well reproduced. A more complex primary production model only marginally improved the model output. The model performs best on high water table wetland sites with relatively high fluxes. The choice of the objective function to compare the model with the data is critical; the often used R-square statistic may give a false impression of the model performance. Comparing the model with eddy covariance data requires upscaling the model with a vegetation map and and the use of a footprint model. PERGAMON meeting: 5-7 November 2013; GEOMAR, Kiel, Germany 8 Land-atmosphere methane fluxes from an arctic floodplain and its adjacent polygonal tundra landscape Runkle, Benjamin R.K. 1, Wille, Christian 1, Holl, David 1, Kutzbach, Lars 1, Alexander Sabrekov 2, Mikhail Glagolev 2 1 Institute of Soil Science, KlimaCampus, University of Hamburg, Germany 2 Moscow State University Faculty of Soil Science, Russia Accurately quantifying methane emissions from permafrost tundra landscapes into the atmosphere is a major concern of the global climate modeling community, and could help constrain the global methane balance, offer predictions in response to global climate change, and advance understanding of these regions’ soil biogeochemistry and landscape ecology. Previous research at our Lena River Delta research site (72° N, 126° E) has found relatively low methane emissions (~18-30 mg m-2 d-1) in the polygonal tundra of the delta’s Holocene river terrace (Sachs et al., 2008; Wille et al., 2008). In summer 2013 we compare methane emissions from this landscape type to the adjacent active river floodplain, a sandy, Equisetum – Salix – Alopecurus alpinus community ecosystem. This landscape has backswamp regions with higher organic matter accumulation though is generally dominated by soils with high sand contents, low organic matter content, and lower water tables than the Holocene terrace (Boike et al., 2013; Zubrzycki et al., 2013). The wet parts of a similar landscape unit in the Indigirka lowlands (71° N, 147° E) have been demonstrated in a short-term chamber campaign to have greater methane emissions than their nearby polygon tundra counterparts (van Huissteden et al., 2005; Van Der Molen et al., 2007). These differences were in part attributed to the annual deposition of nutrients via flooding, increased primary productivity and associated root exudates, and higher soil temperatures. The results presented in this study will compare methane fluxes derived from the eddy covariance technique from the two landscape units. A footprint analysis will be performed to compare wetter and dryer portions of the contributing landscapes to the measurement system. It is expected that the longer, 2-month measurement period (mid-summer to fall freeze-up) will help clarify the mechanisms driving changes in methane emissions from modern active floodplains. As this landscape type covers 40% of the soil-covered area of the Lena River Delta and is analogous to similar regions across the Arctic, increased mechanistic understanding of its methane fluxes will provide valuable insights into the functioning of the terrestrial-fluvial interface. Similarly, the Holocene river terrace is representative of 22% of the Lena River Delta, and as the subject of a longer-term measurement campaign offers the opportunity to contextualize this year’s findings within a spectrum of multi-annual climate conditions. The acquisition of high quality, near continuous flux estimates from these landscapes will significantly constrain methane flux estimates from lowland portions of the terrestrial Arctic. Boike, J., et al. (2003) Baseline characteristics of climate, permafrost and land cover from a new permafrost observatory in the Lena River Delta, Siberia (1998–2011), Biogeosciences, 10(3), 2105–2128. Van Der Molen, M., et al. (2007) The growing season greenhouse gas balance of a continental tundra site in the Indigirka lowlands, NE Siberia, Biogeosciences, 4(6), 985–1003. Van Huissteden, J., et al. (2005) High methane flux from an arctic floodplain (Indigirka lowlands, eastern Siberia), J. Geophys. Res., 110(G2), G02002. PERGAMON meeting: 5-7 November 2013; GEOMAR, Kiel, Germany 9 Relative importance of lake methane emissions in a subarctic peatland landscape, Northern Sweden, depends on spring ice thaw Mathilde Jammet1, Thomas Friborg1, Patrick M Crill2 1Center for Permafrost, Department of Geosciences and Natural Resource Management, University of Copenhagen, 1350 Copenhagen K, Denmark 2Department of Geological Sciences, Stockholm University, Stockholm, Sweden Lakes and ponds are abundant features of northern landscapes where the presence of permafrost and peat prevents water drainage. Northern lakes have been recently argued to be globally significant emitters of methane (CH4), partially offsetting the vegetation carbon sink. Besides, they are likely to play a role in degrading permafrost landscapes as sites of carbon remineralization from adjacent peatlands. Few studies have been published on Arctic lake CH4 dynamics, and even fewer took an integrative ecosystem approach, comparing vegetated area and open-water system within the same catchment. Because of a high temporal and spatial variability, lake-atmosphere CH4 exchanges are notoriously difficult to measure. The eddy covariance (EC) method allows for continuous monitoring and integration of all emissions pathways (ebullition, diffusion, plant-mediated transport). We present here one year of ecosystem-scale data from the Stordalen mire (68°N, 19°E) near Abisko in Northern Sweden, where an eddy covariance (EC) system is used in an innovative way to quantify the importance of CH4 emissions from a shallow lake (average depth < 1.5m) in a palsa mire landscape. The EC system is situated so that it measures either a terrestrial fen surface or a lake surface depending on wind direction which, in Stordalen, is dominated by flow from only two directions. During the ice-free season from June to October 2012, fen emissions clearly dominated with a daily CH4 flux that averages 5 times higher than the lake emissions. During Spring thaw in May 2013, we captured a protracted CH4 burst from the lake. A large degassing occurred over 15 days, showing daily rates of emission higher than the summer maxima observed from both quadrants. Such an event was not observed in the vegetated quadrant. While the fen keeps a connection with the atmosphere during the winter via diffusion through the snow and plant stems, the lake is isolated from the atmosphere during the winter. Likely, CH4 sources that are active during the cold period cannot be released before the connection with the atmosphere is re-established. Our main result is consistent with recent subarctic studies indicating the importance of spring thaw to the annual CH4 flux from seasonally ice-covered lakes. However due to very low lake fluxes in summer the fen surfaces release more CH4 on an annual scale. It is expectable though that, annually, lake fluxes dominate methane emissions from the bog areas. Thus, as permafrost thaws and dry ecosystems switch to fen and ponds in poorly drained areas such as Stordalen, it is very likely than annual mire CH4 emissions will only increase. PERGAMON meeting: 5-7 November 2013; GEOMAR, Kiel, Germany 10 Energy input to subarctic lakes and subsequent methane ebullition Brett F. Thornton1, Martin Wik1, David Bastviken2, Sally MacIntyre3, Ruth K. Varner4, Patrick M. Crill1 1 Department of Geological Sciences and Bolin Centre for Climate Research, Stockholm University, Stockholm, Sweden 2 Department of Thematic Studies—Water and Environmental Studies, Linköping University, Linköping, Sweden 3 Department of Ecology, Evolution, and Marine Biology and Marine Science Institute, University of California, Santa Barbara, California, USA 4 Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, Durham, New Hampshire, USA Freshwater emissions of the potent greenhouse gas methane (CH4) have been suggested to be equivalent in greenhouse gas strength to at least 25% of the C uptake of all land-based ecosystems combined. Methane primarily escapes lake surfaces via diffusion and ebullition (bubbling); the latter is often the dominant component of the total flux. We use four summer seasons of CH4 ebullition data from three subarctic lakes to demonstrate exceptionally strong linear correlations between seasonal bubble CH4 flux and four readily measurable, energy-related parameters of the lakes (solar shortwave (SW) input, number of ice-free days, deep water sediment temperature, and shallow water sediment temperature); r-squared values up to 0.997 were observed. Future changes to energy input to lakes and ponds may thus predictably alter the CH4 source strength of water bodies across northern landscapes. PERGAMON meeting: 5-7 November 2013; GEOMAR, Kiel, Germany 11 High resolution CH4 emissions and dissolved CH4 measurements elucidate surface gas exchange processes in Toolik Lake, Arctic Alaska Tonya DelSontro1,2, Sebastien Sollberger1,2, George W. Kling3, Gaius R. Schaver4, Werner Eugster5 1 Eawag, Swiss Federal Inst. of Aquatic Science, Switzerland 2 ETH Zurich, Inst. Of Biogeochemistry and Pollutant Dynamics, Switzerland 3 University of Michigan, Ann Arbor, MI, USA 4 Marine Biological Laboratory, Woods Hole, MA, USA 5 ETH Zurich, Inst. of Agricultural Sciences, Switzerland Approximately 14% of the Alaskan North Slope is covered in lakes of various sizes and depths. Diffusive carbon emissions (CH4 and CO2) from these lakes offset the tundra sink by ~20 %, and much more if ebullitive CH4 emissions were also considered. These natural CH4 emissions are significant sources to the global CH4 budget and will likely increase in intensity with climate change. Here we present high resolution CH4 emission data as measured via eddy covariance and a Los Gatos gas analyzer during the ice free period from Toolik Lake, a deep (20 m) Arctic lake located on the Alaskan North Slope, over the last few summers. Emissions are relatively low (< 25 mg CH4 m-2 d-1) with little variation over the summer. Diurnal variations regularly occur, however, with up to 3 times higher fluxes at night. Gas exchange is a relatively difficult process to estimate, but is normally done so as the product of the CH4 gradient across the air-water interface and the gas transfer velocity, k. Typically, k is determined based on the turbulence on the water side of the interface, which is most commonly approximated by wind speed; however, it has become increasingly apparent that this assumption does not remain valid across all water bodies. Dissolved CH4 profiles in Toolik revealed a subsurface peak in CH4 at the thermocline of up to 3 times as much CH4 as in the surface water. We hypothesize that convective mixing at night due to cooling surface waters brings the subsurface CH4 to the surface and causes the higher night fluxes. In addition to high resolution flux emission estimates, we also acquired high resolution data for dissolved CH4 in surface waters of Toolik Lake during the last two summers using a CH4 equilibrator system connected to a Los Gatos gas analyzer. Thus, having both the flux and the CH4 gradient across the air-water interface measured directly, we can calculate k and investigate the processes influencing CH4 gas exchange in this lake. Preliminary results indicate that there are two regimes in wind speed that impact k – one at low wind speeds up to ~5 m s-1 and another at higher wind speeds (max ~10 m s-1). The differential wind speeds during night and day may compound the effect of convective mixing and cause the diurnal variation in observed fluxes. PERGAMON meeting: 5-7 November 2013; GEOMAR, Kiel, Germany 12 Effect of lake level variation on methane dynamics in the sediment of Lake Lungern, Switzerland L. TYROLLER1,2, M.S. BRENNWALD1, Y. TOMONAGA1, R. KIPFER1,3 1 Eawag, Swiss Federal Institute of Aquatic Science and Technology, 8600 Duebendorf, Switzerland (*correspondence: lina.tyroller@eawag.ch) 2 ETH Zurich, Institute of Biogeochemistry and Pollution Dynamics, 8092 Zurich, Switzerland 3 ETH Zurich, Institute of Geochemistry and Petrology, 8092 Zurich, Switzerland Lake Lungern, a Swiss hydropower reservoir is characterised by the formation of CH4 bubbles in the sediment due to super saturation of dissolved gases in the porewater and due to lake level variations. Noble gases are powerful tracers for gas transfer processes in lake sediments. They were successfully applied in the sediment of Swiss Lake Sopensee [1] to study CH4 ebullition in the past. In Lake Lungern we determined both CH4 and noble gas concentrations in the porewater with a newly developed method for quantitative sampling of noble gases [2]. In order to asses the depth of active CH4 production, and to investigate gas transfer processes in the lake sediment due to lake level variation we sampled the uppermost metre of the sediment of Lake Lungern. Using the new sampling method, we observed CH4 concentrations exceeding the insitu saturation concentration. Compared to the overlying water body, the noble-gas concentration in the sediment pore-water showed a depletion of the lighter, more volatile gases relative to the heavier, more soluble gases. This elemental fractionation indicates stripping of noble gases into the CH4 bubbles released from the sediment. In addition, the absolute noble gas concentrations in the sediment pore-water indicate an air excess relative to the concentrations in the overlying water body. We attribute this to the formation of excess air resulting from the dissolution of air bubbles entrapped in the sediment when the lake level falls below the depth of our sampling site. Linking CH4 and noble gas concentrations in the sediment pore-water therefore allows assessing importance of the physical transport processes related to CH4 emission from the sediments into the water body of the Lake Lungern. [1] Brennwald et al. (2005) Earth Planet Sc. Lett. 235, 31-4. [2] Tomonaga, Y., Brennwald, M. S., & Kipfer, R. (2011) Limnol. Oceanogr.: Methods 9, 42-49. PERGAMON meeting: 5-7 November 2013; GEOMAR, Kiel, Germany 13 Using isotopes to understand methane formation, removal and transport in the East Siberian Arctic Shelf C.J. Sapart, N. Shakhova, I. Semiletov, C. van der Veen, J. Jansen and T. Röckmann. Methane is a strong greenhouse gas emitted by human activity, but also by natural processes. Large uncertainties exist on the future contribution of natural methane sources (e.g. wetlands and geological sources) to the radiative forcing of the Earth. The Arctic regions are of special concern, because they undergo above average warming causing the thawing of permafrost thus the remobilization of large amount of organic carbon as potential methane precursor. The East Siberian Arctic Shelf (ESAS) is the shallowest and broadest continental shelf on Earth and is overlaid by thawing sub-sea permafrost. In this carbon-enriched environment, in presence of microbes and under anoxic conditions, microbial methane production is enhanced in the seafloor sediment. The methane produced can be stored in the sediment as gas hydrate, oxidized by methanotrophs or diffuse through the water column to the atmosphere. Moreover, old methane (microbial or thermogenic) from the deep ocean crust can be transported to the surface and undergo similar processes. Since a few years, large methane fluxes have been identified to the atmosphere of the ESAS, but the quantitative and qualitative understanding of the methane formation/removal/transport mechanisms remains poor. Between 2008 and 2012, several winter (ice drilling) and summer (cruise) campaigns have been performed to retrieve methane samples from different depths in the sediment and in the water column of the ESAS. We performed chemical analyses as well as measurements of methane mixing ratio and isotopic composition on those samples. Our results allow a better understanding of the different types of methane formation/removal pathways. Moreover, they show that transport throughout the sediment and the water column can significantly alter the stable isotopic signature of the methane produced in the sediment. Hence analyzing methane stable isotopes on atmospheric samples only cannot allow discriminating between the different types of methane sources (thermogenic or microbial). PERGAMON meeting: 5-7 November 2013; GEOMAR, Kiel, Germany 14 Methane production in marine sea ice of the Chukchi Sea, Barrow Alaska Niko Finke1, Steven Baer2, Jeff Chanton3, Samantha B. Joye1 1Department of Marine Sciences, University of Georgia 2Department of Physical Sciences, Virginia Institute of Marine Science 3Earth, Ocean and Atmospheric Science, Florida State University In an ice core taken during the dark winter months at a shallow coastal site of the Chuckchi Sea near Barrow, Alaska, methane concentrations per volume of the iceentrapped brine increased from about 20 times water column concentrations 5 cm above the ice water interface to a maximum about 50 times water column values at 22 cm below the ice air interface. Methane and CO2 production rates were measured in 3 sections (0-10, 20-30, 40-50 cm) of the ice core incubated at -5°C under an air atmosphere either under illumination (100 μmol photons m-2 s-1) or in the dark. Methane production in the dark was highest (~2 nmol lice -1 d-1) in the center section of the core and lowest (~0.5 nmol lice -1 d-1) in the bottom section, CO2 production showed highest rates (~500 nmol lice -1 d-1) in the bottom section and lowest (~80 nmol lice -1 d-1) at the surface. During light incubations methane production was substantially reduced, and CO2 was consumed in the lower 2 sections of the core. Methane production rates were highest shortly after the beginning of a dark period after illumination, suggesting organic carbon derived from photosynthesis might act as precursors for methanogenesis. During light incubations, however, aerobic methane oxidation due to elevated oxygen concentrations could lead to a net decrease in methane production. In the most active top and middle sections, methane produced in the dark had a δ13C of -48.7 ± 0.2 ‰ close to Arctic atmospheric values but substantially lighter than other Arctic biologic sources (Fisher, et al., 2011). In the bottom section the δ13C was -51.0 ± 1.6 ‰ with heavier values in the more active replicate. Methane production in ice will generate a strong methane gradient towards the atmosphere, likely leading to diffusive flux to the atmosphere, as the brine channels make the ice penetrable for gases (Gosnik, et al., 1976). While increased concentrations and a longer residence time of methane under the sea ice could increase the likelihood for aerobic methane oxidation in areas with methane venting from shallow sediment sources, sea ice is a potential huge source for biological methane to the atmosphere due to the sea ice extent. This research was supported by NSF awards to SBJ (# 1023444 and # 0908788); logistical support for work in Barrow was provided by Dr. Patricia Yager through NSF award (# 091025) Fisher RE, Sriskantharajah S, Lowry D, et al. (2011) Arctic methane sources: Isotopic evidence for atmospheric inputs. Geophysical Research Letters 38: L21803. Gosnik TA, Pearson JG & Kelley JJ (1976) Gas movement through sea ice. Nature 263: 41-42. PERGAMON meeting: 5-7 November 2013; GEOMAR, Kiel, Germany 15 Assessing the linkages between seafloor methane seeps and gas hydrate offshore western Svalbard Carolyn Graves1, Andy Stott2, Christian Berndt3, Doug Connelly4, Rachael James4 1School of Ocean and Earth Science, University of Southampton, UK 2National Environment Research Council Life Sciences Mass Spectrometry Facility, Lancaster, UK 3GEOMAR Helmholtz Centre for Ocean Research, Kiel, Germany 4 National Oceanography Centre, Southampton, UK Plumes of methane rising from the seafloor at the landward limit of the gas hydrate stability zone were discovered offshore western Svalbard in 2008. Beneath the plumes, any sediment-bound methane hydrate would have destabilized as a result of recent or on-going warming of bottom waters. The observed release of gas into the overlying water column and towards the atmosphere has thus been attributed, by some authors, to temperature-driven methane hydrate dissociation (Biastoch et al. 2011; Westbrook et al, 2009). We have characterized the chemical and isotopic signatures of: (i) hydrate recovered from close to the bubble plumes, (ii) shallow gas in sediments directly beneath the seep sites, and (iii) gas bubbles entering the water column in order to provide support for, or evidence contrary to, a gas-hydrate dissociation mechanism for methane release offshore Svalbard. A sample of methane hydrate was recovered by gravity coring in a pockmark located 30 km to the northwest of the limit of gas hydrate stability offshore western Svalbard. Sediments in the immediate vicinity of methane seepage were collected by gravity and piston coring and sampled for headspace gases. Gas bubbling into the water column was sampled at the seafloor with the submersible JAGO. All gases were characterized for molecular composition by GC-FID and for the isotopic signature of methane by GC-IRMS. The absence of significant proportions of higher hydrocarbons in all samples suggests that the methane has a biogenic source, while methane carbon isotopic signatures point to a mixed biogenic and thermogenic origin. Carbon isotopic shifts of ± 40 ‰ are observed to result from anaerobic methane oxidation in the sediments, but this does not appear to imprint gas bubbling into the water column, indicating that methane escaping into the ocean effectively bypasses this biogeochemical filter in the gas phase. The chemical and isotopic composition of the hydrate-bound methane is consistent with that of the free gas in sediments below the seafloor seeps, as well as the gas that escapes into the overlying water column. While our data cannot prove that the methane seeps result from dissociation of gas hydrate, they support rather than refute this hypothesis. References: Biastoch, A et al. (2011), Rising Arctic Ocean temperatures cause gas hydrate destabilization and ocean acidification. Geophys. Res. Let. 38:L08602. Westbrook GK et al. (2009) Escape of methane gas from the seabed along the West Spitsbergen continental margin. Geophys. Res. Let. 36:L15608. PERGAMON meeting: 5-7 November 2013; GEOMAR, Kiel, Germany 16 Water column stratification and methanotrophy in Svalbard Susan Mau1, Torben Gentz2, Jan Blees3, Jens Schneider von Deimling4, Elisabeth Helmke2, Daniel Frank McGinnis5, Helge Niemann3, Michael Schlüter2, Ellen Damm2 1 MARUM – Center for Marine Environmental Sciences and Department of Geosciences, University of Bremen, Klagenfurter Str., 28334 Bremen, Germany 2 Alfred Wegener Institute for Polar and Marine Research (AWI), Am Handelshafen 12, 27570 Bremerhaven, Germany 3 Department of Environmental Sciences, University of Basel, Bernoullistrasse 30, 4056 Basel, Switzerland 4 Helmholtz Centre for Ocean Research (GEOMAR), Wischhofstr. 1-3, 24148 Kiel, Germany 5 Department of Experimental Limnology, Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB), Alte Fischerhuette 2, 16775 Stechlin, Germany In the Arctic Seas in the Svalbard region, methane (CH4 ) concentrations were supersaturated with respect to the atmospheric equilibrium (~ 3-4 nM) throughout most of the water column offshore Prins Karls Forland and in Storfjorden. CH4 bubbles are released from the seafloor offshore Prins Karls Forland and a detailed study of a region including 10 gas flares revealed that the salinity-controlled pycnocline situated ~20 m above the seafloor controls the vertical CH4 concentration gradient. While high CH4 concentrations of up to 524 nM were measured below the pycnocline, low CH4 concentrations of less than 20 nM were observed in the water column above. A gas bubble dissolution model indicates that ~80 % of the CH4 released from gas bubbles into the ambient water takes place below the pycnocline. The dissolved CH4 is transported northward and microbially oxidized with a rate of up to 0.78 nM/d. Above the pycnocline, CH4 concentrations decrease to local background concentration of ~10 nM and CH4 oxidation rates are lower (<0.22 nM/d). In Storfjorden, CH4 is suggested to be formed in situ in the upper water column and released from sediments due to turbulent mixing during winter in the deep water. The methanotrophic community in the surface water appears to be adapted to relatively low CH4 concentrations whereas the activity of the deep water methanotrophic community is relatively low at the ambient, summertime CH4 concentrations but has the potential to increase rapidly in response to CH4 availability. CH4 oxidation rate measurements at near in situ CH4 concentrations (measured with 3H-CH4 raising the ambient CH4 pool by < 2 nM) showed increasing rates from the sea-surface to a maximum of ~2.3 nM/d at 60 m, where also highest CH4 concentrations were observed, followed by a decrease in the deeper water. In contrast, rate measurements with 14C-CH4 (incubations were spiked with ~450 nM of 14C-CH4, providing an estimate of the CH4 oxidation at elevated concentration) showed comparably low turnover rates (< 1 nM/d) at 60 m, and peak rates were found in the deep brine-enriched water concomitant with increasing 13C-values in the residual CH4 pool. A similar distinction between surface and deep water methanotrophy is suggested by our molecular analyses. The DGGE banding patterns of 16S rRNA gene fragments of the surface and deep water were clearly different. Concerning methanotrophic bacteria, a DGGE band related to the known Type I methanotrophic bacterium Methylosphaera was observed in deep brine-enriched water, but absent in surface water. Furthermore, the PCR-amplicons of the deep water with the two functional primers sets pmoA and maxF showed, in contrast to those of the surface PERGAMON meeting: 5-7 November 2013; GEOMAR, Kiel, Germany 17 water, additional products besides the expected one of 530 bp. Both studies in the Svalbard area indicate that limited vertical mixing, i.e., stratification, leads to separated water bodies that appear to generate different methane production-removal cycles. At both sites, water column stratification limits the sea-air exchange of CH4 during summer. High temporal variablity of methanotrophic communities offshore Svalbard Lea I. Steinle*1,2, Carolyn Graves3,4, Christian Berndt2, Tomas Feseker5, Moritz F. Lehmann1, Tina Treude2, Helge Niemann1 1University of Basel, Dept. of Environmental Geosciences, CH (*correspondence: lea.steinle@unibas.ch) 2Helmholtz Centre for Ocean Research (GEOMAR), DE 3National Oceanography Centre Southampton, UK 4University of Southampton, UK 5University of Bremen, DE A large number of gas flares were recently discovered at the landward termination of the methane gas hydrate stability zone off Svalbard. Our models indicate that the gas ebullition is most probably caused by seasonal bottom water temperature fluctuations of 1-2°C, causing periodic methane hydrate formation and dissociation. We sampled During an expedition with R/V M.S. Merian in August/September 2012 (MSM 21/4), methane concentrations were consistently elevated in bottom waters (up to 825 nM), providing abundant substrate for aerobic methanotrophs. Our investigations on the spatio-temporal variation of aerobic methane oxidation (MOx) rates revealed highest rates (up to 3.1 nM/day) at ~50 m above the sea floor. Despite constant supply of methane, MOx rates displayed a high temporal variability. Subsequent CARD-FISH analysis showed that high MOx rates are associated with the presence of methanotrophic cell aggregates, also reflected in depleted lipid biomarker compounds and high d13C of the remaining CH4. The identity of the methanotrophs was then determined by generating a 16S clone library. Further comparison of rates/aggregate numbers and water temperature revealed consistent spatio-temporal patterns that suggest an oceanographic control on the magnitude of MOx: Cool Arctic bottom water contains a comparably large standing stock of methanotrophic bacteria. This water mass is episodically displaced by the warmer W-Spitsbergen current, which is depleted in methanotrophic biomass. Our data thus imply that MOx fluctuations offshore Svalbard are indirectly controlled by ocean circulation patterns rather than methane substrate availability. PERGAMON meeting: 5-7 November 2013; GEOMAR, Kiel, Germany 18 Hydroacoustic quantification of free-gas venting offshore Svalbard, Arctic: Changes in space and time Veloso M.1, Greinert J. 1, 2, 3, 4, Mienert J.4, De Batist M.1 1 Renard Centre of Marine Geology, Ghent University, Krijgslaan 281 s.8, 9000-Ghent, Belgium 2 GEOMAR Helmholtz Centre For Ocean Research Kiel, Wischhofstrasse 1-3, 24148 Kiel, Germany. 3 Royal Netherlands Institute for Sea Research (NIOZ), 1790 AB Den Burg (Texel) Netherlands 4 CAGE - Centre for Arctic Gas Hydrate, Environment and Climate, UiT The Arctic University of Norway, Dramsveien 201, N-9037 Tromsø,Norway Hydroacoustic data from a seep site area offshore Spitsbergen have been collected since 2009 by RV Helmer Hanssen (U. Tromsoe) in order to monitor the dynamics of gas bubble seepage and evaluate the amount of CH4 released at the seafloor. A large number of acoustic flares have been detected during four years of data acquisition at an intensely seeping area close to the shelf edge in 240m water depth and further down-slope between 330 and 450m water depth covering the top of the gas hydrate stability zone. Water column data were collected with an EK60 splitbeam echosounder system. Seep positions were determined by accounting for motion and using split-beam information to determine the ‘flare spine’ for seep location as accurately as possible. The inverse hydroacoustic method for flux estimation developed by Muyakshin et al. (2010) has been adapted to be used with the angle information derived from splitbeam data and using gridding algorithms for generating acoustic maps for each of the four surveys. The method evaluates the flux using the backscattering volume strength (SV) above the seafloor produced by free gas release, a bubble size distribution (BSD) function obtained from video footage and models for bubble rising speed (BRS) taken from the literature. Methane flux calculations depending on these input parameters vary from 187 T/yr to 250 T/yr assuming a continuous discharge for the 240m deep shelf-edge site, when all data sets are merged. Compared to other fluxes e.g. from specific seep areas in the Black Sea (683 T/yr Greinert et al., 2010 JGR; 1376 T/yr Römer et al., 2012 MarGeo) or the Håkon Mosby mud volcano (181 T/yr Sauter et al., 2006 EPSL) the fluxes from offshore Svalbard are similar in range but on the lower end. However, studying the ‘common area’ which was insonified during all four years reveals a decreasing flux of about 20% although the actual seep positions have been very persistent. The reason for this is currently unknown. The geochemical water column data gathered so far could indicate a slight impact on methane sea surface concentrations caused by ‘seepage’ and bottom water transport via internal wave breaking. Air sampling does not reveal a measurable increase, though, that could be linked to this marine methane source and the question remains to which extent marine sources contribute to methane fluxes into the atmosphere in the future. PERGAMON meeting: 5-7 November 2013; GEOMAR, Kiel, Germany 19 Atmospheric methane flux from a methane seep field south of the Dogger Bank, Dutch North Sea John W. Pohlman1, Jens Greinert2,3, and Carolyn Ruppel1, Janine Nauw2, Peter Urban3, Jurre de Vries2, Petra Bombach4, Corina Brussard2, Emile Bergeron1 1USGS, 2Royal NIOZ, 3GEOMAR, 4 North Sea monitoring surveys conducted by the Netherlands Institute of Sea Research (NIOZ) in 2011 and 2012 documented vigorous bubbling of methane from the seafloor in Block 13 of The Netherlands North Sea sector. In September 2013, Leg 1 of the NIOZ North Sea monitoring survey re-occupied the site for 4 days to quantify the magnitude of methane flux from the seafloor, its distribution in the water column and emission to the atmosphere. Persistent release of methane from the seafloor at an accessible and spatially well-defined marine setting with a shallow water column (< 50 m water depth) is an excellent ‘natural laboratory’ for investigating how shallow marine ecosystems respond to methane inputs. The value this study and site monitoring at this location is heightened by recent reports suggesting similarly shallow methane seeps overlying climate-sensitive permafrost and marine gas hydrate are vulnerable to catastrophic methane release. Atmospheric methane fluxes were quantified using the US Geological Survey (USGS) dual-cavity ring-down spectrometer (CRDS) based greenhouse gas (GHG) flux system. The USGS-CRDS-GHG flux system provides real-time and continuous measurements of surface water concentration and stable carbon isotope content of methane and carbon dioxide, as well as atmospheric methane and carbon dioxide concentrations of methane and carbon dioxide from as many as four (4) elevations overlying the air-water interface. In combination with meteorological data from sonic anemometers co-located with the air intakes, mass fluxes of methane and carbon dioxide via diffusive and ebullitive (bubble) fluxes are possible. During Cruise 64PE376, we obtained data during approximately 95% of time at sea, including transit and site operations. Preliminary concentration and flux data will be presented and interpreted within the context of complementary vertical concentration profiles of dissolved methane, sonar imaging of bubble distribution in the water column and acoustic analysis of current and tidal dynamics controlling methane transport and distribution. PERGAMON meeting: 5-7 November 2013; GEOMAR, Kiel, Germany 20 Subsea permafrost degradation and inferred methane release in shallow coastal water of the Central Laptev Sea Overduin, P. P.1, Liebner, S.2 , Knoblauch, C.3, Kneier, F.1, Günther, F.1, Schirrmeister, L.1, Wetterich, S.1 1 Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Potsdam, Germany 2 GFZ German Research Centre for Geosciences, Potsdam, Germany 3 Institute of Soil Science, University of Hamburg, Hamburg, Germany The degradation of permafrost beneath the seabed on the East Siberian Shelf has been implicated in the release of greenhouse gases, especially methane, and the potential de-stabilization of gas hydrates. We investigate the degradation of subsea permafrost using geophysical methods, drilling and temperature measurements. Recovered subsea sediments offer an opportunity to investigate sediment composition, reconstruct permafrost degradation processes, and to better understand the consequences of this degradation. A 52 m deep borehole was drilled about 800 m offshore to the west of the Buor Khaya Peninsula in the central Laptev Sea. Coastal exposures and an onshore borehole revealed “ice complex” stratigraphy with high ice and carbon contents. The landscape of the Buor Khaya Peninsula, however, has undergone substantial degradation, so that isolated islands of relatively intact ice complex cover about 15% of the area among a palimpsest of thermokarst basins. The subsea sediment was mostly sandy with spatially highly variable carbon contents and isolated layers of woody plant remains probably deposited in a fluvial environment before freezing. Ice-bonded permafrost was encountered at 28 m b.s.l. The western coast of the Buor Khaya Peninsula has been retreating at between 1 and 2 m per year. The position of the ice-bonded permafrost table with distance from shore suggests that subsea permafrost degrades at a mean rate of 3 to 4 cm a-1 following erosion. Methane was entrapped throughout the frozen sediment suggesting the mobilization of methane along with permafrost degradation at this site. PERGAMON meeting: 5-7 November 2013; GEOMAR, Kiel, Germany 21 Methane production, oxidation and emission in the Laptev Sea Shelf Samarkin V.A.1, Shakhova N.E.2, Semiletov, I.P.2 and S.B. Joye1 1Department of Marine Sciences, University of Georgia, Athens, 2International Arctic Research Center, University of Alaska, Fairbanks The Arctic region contains a huge amount of organic carbon buried inland and within the Arctic Ocean sedimentary basin. This organic matter may become entrained in the active biogeochemical carbon cycling due to thawing of terrestrial and subsea permafrost. The East Siberian Arctic Shelf (ESAS) is a very important part of the Arctic shelf; it constitutes significant fraction of (~25%), and is home to more than 80% of the Arctic shelf subsea permafrost and permafrost-related unique Arctic shelf hydrates that are predicted to exist. The current ESAS annual atmospheric CH4 venting, which occurs via both gradual ebullition and diffusion, is on par with previous estimates of CH4 venting from the entire World Ocean (Shakhova et al., 2010). New data obtained during research cruises in 2011-2012 show widespread distribution of flare-like methane seep structures 1000-1300m in diameter rising from the seabed of the Laptev Sea. These flares travel through the water column from as deep as 90 m and transfer methane to the atmosphere. The best candidate responsible for such CH4 releases is degrading subsea permafrost and decaying deposits of CH4 within and beneath it. We measured methane oxidation rates in waters and sediments of the Laptev Sea shelf using 3H and 14C- labeled methane and methanogenesis rates in sediments using 14C-labelled bicarbonate and acetate. Calculations of CH4 balance suggest that anaerobic and aerobic methane oxidation almost eliminates diffusive CH4 flux from the sediments. Methane oxidation in deep salty waters is slow and does not influence significantly on CH4 ebullutive flux to the atmosphere. For better understanding of possible methane sources for high methane fluxes in this area carbon and hydrogen stable isotope signatures of CH4 in sea water, surface and deep drill core sediments were measured. Delta 13C and δD values of CH4 dissolved in waters in the drill site varied from -37.8‰ for δ13C (-31.3‰ for δ D) to - 75.7‰ for δ13C (-146.1‰ for δD). The range of δ13C values of methane in the surface sediments was from -51.3 ‰ for δ13C (-262.0‰ for δD) to -58.2‰ for δ13C (- 125.5‰ δD) and in drill core samples (up to 26.5 m depth) from -77.8 ‰ for δ13C (- 177.2‰ for δD) to -100 for δ13C (-232.2 ‰ δD). Methane carbon and hydrogen isotope signatures in water may reflect various sources of CH4 and influence of aerobic methane oxidation that is slow in salt waters and is high in surface sediments. Significant depletion of methane from drill core with δ13C (to -100‰) is characteristic of slow hydrogenotrophic methanogenesis at cold near 0° C in situ temperatures, which was confirmed with 14C- radiotracer rate measurements. These data will be used as input to numerical models, which will be developed to describe the thermodynamic and biogeochemical aspects of permafrost/CH4 dynamics. Using field data and modeling, projection of future dynamics in CH4 fluxes from the ESAS will be made. PERGAMON meeting: 5-7 November 2013; GEOMAR, Kiel, Germany 22 Russian Arctic Ocean Ground Reference of Entire Arctic Ocean Satellite Methane Observations Ira Leifer, Leonid Yurganov, Natalia Shakhova, Igor Semiletov, Chris Stubbs Recently global atmospheric methane concentrations have begun increasing after a period of near stabilization. Although the reasons are not yet well established, Arctic sources have been proposed related to rapidly warming Arctic Oceans. Warming Arctic oceans could release methane sequestered under submerged permafrost and as hydrates, as well as from increased microbial production in shallow seas. Although Arctic shipboard surveys have demonstrated extensive bubble methane releases in the East Siberian Arctic Sea and elsewhere, cruise only provide a snapshot. Only satellite data provides the spatial and temporal coverage to evaluate overall contributions to global budgets. Analysis of thermal satellite data over the last decade suggests that methane emissions particularly for the Kara Sea, East Siberian Arctic Sea, Barents Sea and Norwegian Sea are significant. Surface groundreference data confirms the overall satellite data interpretation, and provides new emissions estimates. PERGAMON meeting: 5-7 November 2013; GEOMAR, Kiel, Germany 23 Methane blowout in the North Sea: A natural laboratory to study the adaptation of methanotrophic microorganisms Philipp Wilfert1,3, Lea Steinle1,2, Stefan Krause1, Peter Linke1, Volker Liebetrau1, Matthias Haeckel1, Mark Schmidt1, Helge Niemann2 and Tina Treude1, 1 GEOMAR Helmholtz Centre for Ocean Research Kiel, Wischhofstrasse 1-3, D-24148 Kiel, Germany 2 University of Basel, Dept. of Environmental Sciences, Bernoullistrasse 30, 4056 Basel, Switzerland 3Presenting author: pwilfert@geomar.de Methane is a very potent greenhouse gas. Its emissions from the ocean are controlled by microbial processes in anoxic (anaerobic oxidation of methane, AOM) and oxic (aerobic oxidation of methane, MOx) environments. In sediments, AOM provides a long-term sink for methane via the formation of bicarbonate which is often precipitated as methane-derived authigenic carbonates (MDAC). So far, studies about the adaptation of the benthic methane filter to increases in methane fluxes are rare. In 1990 an oil rig accidently penetrated a shallow gas pocket in the northern North Sea and caused a blowout that formed a 20 m deep crater at the seafloor. Until today, the blowout releases significant amounts of methane. This site provides a unique natural laboratory to study the development of a methanotrophic community in a newly formed methane seep. Intact sediment cores (0-18 cm below seafloor) were taken by video-guided push coring using a ROV (Kiel 6000; GEOMAR Kiel). Cores were sampled within the centre of the blowout crater, at the slope of the crater, and at a reference site 50 m away from the crater. Sediments were used to determine ex-situ and in-vitro rates of AOM as well as the abundance of AOM organisms. AOM rates in the centre were extremely high (up to 3.4 μmol cm-3 d-1 and 435 mmol m-2 d-1), due to a very broad and active AOM zone of at least 18 cm. AOM rates in the slope and reference cores were low or absent. Considering these high AOM rates at the blowout site, MDAC formation is feasible within 20 years. Samples from sediments of the blowout crater were analysed for their mineral- and stable isotope composition (δ13C and δ18O). However, no indications for MDAC were found. Unspecific cell staining, using DAPI, revealed cell aggregates morphological similar to the microbial consortia mediating AOM. These aggregates were found in the sediments from the centre of the crater where they occurred in high numbers, the aggregates were absent in the reference core. Additionally the water column was sampled at three different depths in a grid above the blowout to measure methane concentrations and MOx rates. Radiotracer-based measurements indicated very high methane turnover rates above the methane release inside the blowout crater (70 nmol L-1 d-1) indicating an active MOx community. This study demonstrates that the methanotrophic community at the North Sea blowout is extremely active; suggesting that adaptation to strongly increasing methane fluxes, even in sediments, might be in the order of decades. In sediments of the blowout crater high permeability probably facilitates fast sulphate replenishing and removal of AOM end-products, thereby boosting AOM activity and inhibiting carbonate precipitation. PERGAMON meeting: 5-7 November 2013; GEOMAR, Kiel, Germany 24 Efficiency of the benthic microbial methane filter beyond steadystate conditions Philip Steeb1, Peter Linke1, Tina Treude1 1Helmholtz-Centre for Ocean Research GEOMAR, Kiel 24148, Germany, psteeb@geomar.de Marine sediments and sub-seafloor gas hydrates build one of the largest methane reservoirs on earth. Most of the methane ascending in sediments is oxidized by anaerobic oxidation of methane (AOM) with sulfate as terminal electron acceptor, the so-called “benthic microbial methane filter”. The efficiency of the benthic microbial methane filter is controlled by diffusive sulfate supply from seawater and advective methane flux from deep reservoirs. High fluid fluxes reduce the penetration depth of sulfate and limit the filter to a very narrow zone close to the sediment-water interface. However natural and catastrophic fluctuations of methane fluxes (caused e.g. by gas hydrate melting, earthquakes, slope failure) can change the fluid regime and reduce the capability of this greenhouse gas sink. A new Sediment-Flow-Through (SLOT) system was developed to incubate intact sediment cores under controlled fluid regimes. To mimic natural fluid conditions sulfate-free, methane-loaded artificial seawater medium was pumped from the bottom and sulfate-enriched seawater medium was supplied from above. Media and system were kept anoxic and seepage medium was tracked with bromide tracer. Over the entire experiment, the change of geochemical gradients inside the sediment column was monitored in monthly time intervals using porewater extraction/analyses and microsensor measurements. In addition, in- and ouflow samples were analyzed for the calculation of methane turnover rates. In the above manner, sediments from different seeps (Eckernförde Bay, Costa Rica, Chile, and the Eastern Mediterranean Sea) and types (gassy sediments, gas hydrates containing sediments, mud volcanoes, sulfur bacteria mats, pogonophoran fields, clam fields) were incubated and monitored up to one year. Moderate to high advective fluid flow rates, which have been reported from natural seeps, were chosen to challenge the benthic microbial methane filter and investigate the response to pulses of methane loaded fluids. By comparing preconditions, efficiency, and response time of the different sites and habitats, we like to discuss formative influences and physico-chemical conditions (e.g. porosity and permeability) for adaptability of the different sediments. PERGAMON meeting: 5-7 November 2013; GEOMAR, Kiel, Germany 25 Record of methane emissions from the West Svalbard continental margin during the last 16,000 years: results from benthic foraminifera. Giuliana Panieri1, Rachael H. James2, Angelo Camerlenghi3, and Graham K. Westbrook2,4,5 1 CAGE - Centre for Arctic Gas Hydrate, Environment and Climate, UiTThe Arctic University of Norway, Tromsø, Norway 2 National Oceanography Centre, University of Southampton Waterfront Campus, European Way, Southampton, SO14 3ZH, UK 3OGS IstitutoNazionale di Oceanografia e di GeofisicaSperimentale, BorgoGrottaGigante 42/C, 34010 Sgonico, Trieste, Italy 4School of Geography, Earth and Environmental Sciences, University of Birmingham, Birmingham, B15 2TT, UK 5Géosciences Marines, Ifremer Centre de Brest, 29280 Plouzané, France One way to detect marine methane emissions is by carbon isotope (δ 13C) analysis of benthic foraminifera. Thus, in an effort to reconstruct the record of past methane emissions from the Arctic seafloor, we have conducted δ13C analyses of benthic foraminifera, together with other geochemical, micropalaeontological and sedimentological analyses, on a hydrate-bearing sediment core collected from the Vestnesa Ridge(west of Svalbard at ~79° N), a large sediment drift in the Fram Strait representing one of the northernmost gas hydrate provinces along the Arctic continental margins.While foraminifera from some intervals have δ 13C within the normal marine range (0 to -1‰), five intervals are characterised by much lower δ 13C, as low as -17.4‰.These intervals are interpreted to record the incorporation of 13Cdepleted carbon in the presence of methane emissions with δ 13C values ranging from -45 to -80‰ at the seafloor during biomineralization of the carbonate foraminiferal tests and subsequent secondary mineralization. The data reveal that at least five methane emission events have occurred over the past ~16,000 in the Vestnesa Ridge. PERGAMON meeting: 5-7 November 2013; GEOMAR, Kiel, Germany 26 Coupling and feedbacks in the thermogenic gas hydrate system of the Arctic 1 Mienert, Jürgen; 1,2 Carroll, JoLynn; 1,2 Carroll, Michael; 1 Bünz, Stefan; 1Andreassen, Karin; 1 Ferré, Benedicte; 1 Panieri, Guiliana, 1, 3 Knies, Jochen; 1Rasmussen, Tine; 1 Vadakkepuliyambatta, Sunil; 1 Portnov, Alexey; 1Plaza Faverola, Andreia; 1,3 Chand, Shyam, 4 Cherkashov, Georgy; 5 Myhre, Catherine Lund 1 CAGE - Centre for Arctic Gas Hydrate, Environment and Climate, UiT The Arctic University of Norway, Tromsø, Norway 2 Akvaplan-niva AS, Fram Centre, Tromsø, Norway 3 NGU – Geological Survey of Norway, Trondheim, Norway 4 SPSU - I.S. Gramberg All-Russia Research Institute for Geology and Mineral Resources of the World Ocean (VNIIOkeangeologia), St. Petersburg 190121, Russia 5 NILU – Norwegian Institute for Air Research, Kjeller, Norway Recent hydrocarbon explorations in the Arctic regions offshore Norway and Russia have shown a coupling between deeper hydrocarbon sources and the shallow gas hydrate and gas accumulation and release system. The timing and dynamical behaviour of the coupling is not yet well known, but recent Arctic surveys discovered extensive bubble release in both formerly ice-sheet impacted and ice-sheet free regions. Today’s sub-seabed methane hydrate reservoirs remain elusive targets for both unconventional energy and as a natural methane emitter that influences ocean environments, ecosystems and potentially climate, if methane is released in large quantities from the Arctic Ocean to the atmosphere. A rising sea-level in post glacial times flooding Arctic shelves have caused a degradation of offshore permafrost while rising Arctic Ocean temperatures in recent times are causing a destabilization of shallow gas hydrate reservoirs in offshore permafrost and non-permafrost regions at unknown rates and response times. The Svalbard region appears to be peculiar with thin gas hydrate stability zones which can be influenced by small changes in bottom water temperature. Therefore, the Svalbard region is an ideal experimental location where the dynamics from glacial to postglacial times of an ice-sheet impacted region allows studying these processes and generating needed knowledge for future predictions. CAGE - Centre for Arctic Gas Hydrate, Environment and Climate is investigating the role of methane hydrates in arctic areas, and the effects it will have on oceans and on our climate in the future. Several ongoing and planned research projects are part of CAGE. For example MOCA (see poster) will quantify the present atmospheric effects of methane and potential climate impacts on decadal to centennial timescales. MOCA will be carried out in cooperation between CAGE at UiT The Arctic University of Norway, the Norwegian Institute for Air Research (NILU), and the Center for International Climate and Environmental Research – Oslo (CICERO). CAGE was established by UiT The Arctic University of Norway, in close cooperation with the Geological Survey of Norway (NGU). The Centre was awarded the prestigious status as a Norwegian Centre of Excellence (CoE) in November 2012 following an intense competition with 138 other research centres from different disciplines. The appointment gives funding from The Research Council of Norway for a period of ten years, and a unique opportunity to conduct basic research with a longterm scope. PERGAMON meeting: 5-7 November 2013; GEOMAR, Kiel, Germany 27 An extensive collaboration with research groups in Europe, Russia and North America will bring international recognition to the Centre in the years to come. CAGE will also make use of the new state-of-the-art Norwegian polar icebreaker research vessel – F/F «Kronprins Håkon» – which will be launched in 2015/2016 and based in Tromsø. PERGAMON meeting: 5-7 November 2013; GEOMAR, Kiel, Germany 28 Talks in relict submarine permafrost and methane hydrate deposits: Pathways for gas escape under present and future conditions Jennifer M. Frederick & Bruce A. Buffett Earth & Planetary Science Department, University of California Berkeley, USA Permafrost-associated methane hydrate deposits exist at shallow depths within the sediments of the Arctic continental shelves. This icy carbon reservoir is thought to be a relict of cold glacial periods, when sea levels are much lower, and shelf sediments are exposed to freezing air temperatures. During interglacials, rising sea levels flood the shelf, bringing dramatic warming to the permafrost and gas hydrate bearing sediments. Degradation of this shallow-water reservoir has the potential to release large quantities of methane gas directly to the atmosphere. Although relict permafrost-associated gas hydrate deposits likely make up only a small fraction of the global hydrate inventory, they have received a disproportionate amount of attention recently because of their susceptibility to climate change. This study is motivated by several recent field studies which report elevated methane levels in Arctic coastal waters. While these observations are consistent with methane release as a result of decomposing submarine permafrost and gas hydrates, the source of gas cannot easily be distinguished from other possibilities, including the escape of deep thermogenic gas through permeable pathways such as faults, or microbial activity on thawing organic matter within the shelf sediments. In this study, we investigate the response of relict Arctic submarine permafrost and permafrost-associated gas hydrate deposits to warming with a two-dimensional, finite-volume model for two-phase flow of pore fluid and methane gas within Arctic shelf sediments. We track the evolution of temperature, salinity, and pressure fields with prescribed boundary conditions, and account for latent heat of water ice and methane hydrate formation during growth/decay of permafrost or methane hydrate. The permeability structure of the sediments is coupled to changes in permafrost. We assess the role of taliks (unfrozen portions of continuous permafrost) as a pathway for methane gas escape and make predictions of gas flux to the water column as a result of relict permafrost-associated gas hydrate dissociation due to natural climate variations. Several hydrate saturation values (20%, 50%, 80% pore volume within hydrate layers) and talik widths (0.5 km, 1.0 km, 1.5 km, 2.0 km) are explored for model parameters representative of the 20 m isobath at the North American Beaufort and East Siberian Arctic Seas (ESAS). Preliminary results estimate the maximum present-day gas flux at the North American Beaufort is 0.229 kg yr-1 m-2, which produces a methane concentration of 75 nM in the overlying water column. For the ESAS, preliminary results estimate the maximum average present-day gas flux is 0.285 kg yr-1 m-2, which produces a methane concentration of 471 nM in the overlying water column. A desired outcome of this study is to provide a framework for discussion on the potential magnitude of methane release that might be attributed to relict permafrost-associated hydrate deposits in regions where the submarine permafrost has been compromised. PERGAMON meeting: 5-7 November 2013; GEOMAR, Kiel, Germany 29 Stratigraphic, structural and thermodynamic controls on the presence of free gas and gas hydrate beneath the seabed, offshore west Spitsbergen: evidence from high-resolution seismic reflection data. G.K. Westbrook1, 2, S. Ker2, B. Marsset2, T.A. Minshull1 1 School of Ocean and Earth Science, National Oceanography Centre Southampton, University of Southampton, European Way, Southampton SO14 3ZH, U.K. 2 IFREMER, G´eosciences marines, Centre de Brest, Plouzan´e, France It is evident from the many plumes of gas bubbles emanating from the seafloor that free methane gas exists beneath the seabed offshore west Spitsbergen in water depths of less than 400 m. The distribution of gas in the sediment beneath the seabed, however, is less evident, especially in deeper water, where the seabed and shallow sediments lie within the methane hydrate stability field. The evidence for the distribution of gas in sediments is primarily seismic, expressed as changes in the amplitude and polarity of reflectors, locally increased attenuation of seismic waves, scattering, and reduction in seismic velocity. Identifying hydrate is more difficult, depending upon the identification of zones with higher seismic velocity than is normal for the same lithology in the same state of compaction. Also, but unusually, a high saturation of a high-porosity layer by hydrate can produce a strong reflector. At the base of the gas hydrate stability zone (GHSZ), a reflector (BSR) is produced by the seismic impedance contrast between sediment containing gas and sediment containing hydrate. The BSR can be identified easily in water depths greater than about 550 m, where it occurs in predominantly hemipelagic sediment, but it is not obvious in shallower water, where glacigenic sediment is prevalent. Beneath the shallower seabed, the upper limit of seismic evidence for gas provides a broad definition of the base of the GHSZ. Here, gas is restricted to the locally more permeable, beds although there are local exceptions where gas migrates to the seabed. As the seabed shallows, there is an increasing difference between the depth of the base of the GHSZ predicted by equilibrium formulae for the stability of methane hydrate and the greater depth of the GHSZ indicated by the BSR and the general upper limit of gas indicated by seismic anomalies. This difference could be caused by a strong landward reduction in the background geothermal gradient, but it is more probably caused by increasing gas overpressure beneath the shallowing seabed and by the delayed increase in subsurface temperature in response to increasing seabed temperature resulting from the enthalpy of hydrate dissociation and the low thermal diffusivity of the sediment. A deep-towed high-resolution seismic system, SYSIF, with a chirp source (bandwidth 220-1050 Hz, providing a vertical resolution of about 1 m), deployed to complement conventional high-resolution multichannel seismic reflection surveys, revealed the stratigraphy and structure of the uppermost 100-200 m of sediment in great detail, showing pathways that supply the gas to active gas seeps. Numerous mass-flow deposits and channels with incoherent fill appear to act as barriers to gas migration, presumably because of the poor sorting of sediment in them. There are very few distinct faults in the sediment sequence, and it is inferred that the migration of gas through less permeable sedimentary units is normally through fractures, probably opened by gas overpressure. Distinguishing between gas-saturated features at PERGAMON meeting: 5-7 November 2013; GEOMAR, Kiel, Germany 30 different scales with boundaries of varying sharpness and the identification of possible reflectors related to hydrate or carbonate was enhanced by the comparison of the conventional with the SYSIF seismic records. The response of methane hydrate beneath the seabed offshore Svalbard to ocean warming during the next three centuries Héctor Marín-Moreno1, Timothy A. Minshull1, Graham K. Westbrook1, Bablu Sinha2 and Sudipta Sarkar 1* 1National Oceanography Centre Southampton, University of Southampton, UK 2National Oceanography Centre, Southampton, UK Methane is a potent greenhouse gas and large-scale rapid release of methane from hydrate may have contributed to past abrupt climate change inferred from the geological record. The discovery in 2008 of over 250 plumes of methane gas escaping from the seabed of the West Svalbard continental margin at ~400 m water depth (mwd), suggests that hydrate is dissociating in the present-day Arctic. Here, we model the dynamic response of hydrate-bearing sediments, using the TOUGH + HYDRATE (T+H) v1.2 Code, over a period of 2300 yr and investigate ocean warming as a possible cause for present-day and likely future dissociation of hydrate, within 350-800 mwd, west of Svalbard. Future temperatures are given by two climate models, HadGEM2 and CCSM4, and forcing-scenarios, representative concentration pathways (RCPs) 8.5 and 2.6. The initial model is constrained, in terms of the present-day sub-seabed distribution of gas and hydrate, by seismic data that image the BSR in water depths of more than 580 m and the upper limit of gas-related reflectors in shallower water. The initial model was not arbitrarily defined, but was ‘grown’ over the past 2000 yr, driven by a model of changing ocean temperature, to provide a present-day sub-seabed distribution of gas and hydrate that is close to that indicated by the seismic data. Our results suggest that the active dissociation area between latitudes of 78°26’N-78°40’N (~25 km length) will extend to ~480 mwd by 2100 CE and to ~550 mwd by the 2300 CE. Over the next century, 3.9-6.9 Gg yr-1 of methane may be released to the Artic Ocean on the West Svalbard margin, and over the next three centuries 5.3-29 Gg yr-1, if using RCP 2.6 or RCP 8.5, respectively. The emissions predicted from this small area are only a little smaller than the estimated total methane emissions from all natural wetlands at 70°-80°N, which is currently 100 Gg yr-1 . PERGAMON meeting: 5-7 November 2013; GEOMAR, Kiel, Germany 31 Methane in the Western Arctic Ocean: No Evidence for an Arctic Methane Catastrophe Carolyn Ruppel (USGS), John Pohlman (USGS), Mary Pack Woo (UC-Irvine), Michael Casso (USGS), Patrick Hart (USGS), and Laura Brothers (USGS) Since 2010, the US Geological Survey’s Gas Hydrates Project has focused its climate-hydrates studies on the Western Arctic Ocean. In the Central US Beaufort Sea, we have acquired sub-bottom water column imagery, used cavity ring-down spectroscopy (CRDS) to measure greenhouse gas (GHG) concentrations in nearsurface ocean waters and the overlying atmosphere, and collected discrete water samples to determine methane concentrations and oxidation rates. The resulting regional data constrain methane distribution, leakage, oxidation rate, and oceanatmosphere flux and are supplemented by thousands of kilometers of real-time CRDS data collected on the icebreaker Healy in October 2012 and 2013. Those data record GHG concentrations, atmospheric marine boundary layer GHG gradients, and the δ13C of carbon in CO2 and CH4 in near-surface waters from the Bering Strait on the west to Amundsen Gulf on the east. Taken together, the data yield oceanatmosphere methane fluxes over a wide swath of the Western Arctic Ocean and in several distinct settings (shelf, slope, deep Canada Basin) and provide the first modern constraints on the strength of the water column methane sink in the Western Arctic. On the Central Beaufort Sea shelf, the results reveal ubiquitous shallow subseafloor gas that appears unconnected to dissociating gas hydrate or other deep sources. The presumed origin of this gas (in situ microbial production) is consistent with our results that show a limited extent for subsea permafrost and therefore relict gas hydrates on this margin. Although the only locations with elevated methane flux in our dataset occur in nearshore areas underlain by subsea permafrost, the δ13C data confirm that these fluxes are derived primarily from shallow microbial gas, not dissociation of deeper thermogenic gas hydrates. On the Beaufort Sea upper continental slope, where the deepwater gas hydrate system thins to vanishing at ~350 m water depth, seismic and oceanographic data imply a highly dynamic gas hydrate system that has likely dissociated and re-formed several times in the past few decades. Water column methane concentrations in near-seafloor waters are elevated over the upper continental slope, but the ocean-atmospheric methane flux remains low at these sites. This finding is consistent with other research that concludes that methane emitted at water depths of several hundred meters does not reach the ocean surface. Despite the widespread presence of methane in seafloor sediments and indirect evidence that some of the methane is leaking into the ocean, neither the shelf nor slope data sets imply an ongoing “methane catastrophe” in US Beaufort Sea in response to warming climate conditions and significantly reduced ice cover. The pan-Western Arctic Ocean data collected on the Healy also confirm generally low ocean-atmosphere methane fluxes. PERGAMON meeting: 5-7 November 2013; GEOMAR, Kiel, Germany 32 Alaskan Beaufort Sea Heat Flow and Ocean Temperature Analysis: Implications for Stability of Climate-Sensitive Continental Slope Gas Hydrates Benjamin J. Phrampus1*, Matthew J. Hornbach1, Carolyn D. Ruppel2, Patrick E. Hart3 1Huffington Department of Earth Sciences, Southern Methodist University, Dallas, TX 75275 2U.S. Geological Survey, 384 Woods Hole Road, Woods Hole, MA 02543 3U.S. Geological Survey, 345 Middlefield Road, Mail Stop 999, Menlo Park, CA 94025 Based on USGS estimates, gas hydrates beneath the continental slope of the US Beaufort Sea sequester several gigatons of methane. Warming of Beaufort Sea intermediate waters has the potential to cause dissociation of upper slope gas hydrates, release of methane to the overlying water column, and the buildup of pore pressure in slope sediments in an area first used by Kayen and Lee [1991] as the archetype for linked gas hydrate dynamics and slope failures. Limited constraints on regional heat flow, ocean temperature variability, and the extent of methane hydrates across the region have made analysis of Beaufort continental slope gas hydrate system difficult. Using legacy USGS seismic data combined with a new 3D thermal refraction model and more than 30 years of ocean temperature measurements, we analyze the stability of Beaufort continental slope methane hydrates. Our analysis provides the first regional heat flow map of the Alaskan shelf and margin, a detailed >30 year assessment of ocean temperature change in this region, and the first map revealing where disequilibrium methane hydrate stability conditions exist in the Western Beaufort Sea. Our results show that heat flow is complex and highly variable across the Beaufort margin, that intermediate ocean temperatures have warmed steadily for more than 30 years, and that the gas hydrates on the upper slope are out of equilibrium with overlying intermediate waters over large parts of the area. The discrepancy between observed and predicted hydrate stability depths is best explained by significant (>1 oC) intermediate ocean warming since the last glacial maximum. Even in the absence of persistent ocean warming conditions in the near future, the results predict destabilization of gas hydrates underlying an area ranging from ~4,750 km2 to ~30,000 km2 on the US Beaufort continental slope over the next 100 years. A fraction of the methane released by these gas hydrates may be emitted at seafloor seeps and contribute to ocean acidification once oxidized to CO2. Much of the methane and released water produced by gas hydrate dissociation will likely remain trapped in sediments, increasing pore pressures and the likelihood of submarine slope failures. PERGAMON meeting: 5-7 November 2013; GEOMAR, Kiel, Germany 33 A two-dimensional model of the methane cycle on the Siberian continental shelf and slope David Archer Department of the Geophysical Sciences, University of Chicago A two-dimensional model of a passive continental margin was adapted to the simulation of the methane cycle on Siberian continental shelf and slope, attempting to account for the impacts of glacial / interglacial cycles in sea level, alternately exposing the continental shelf to freezing conditions with deep permafrost formation during glacial times, and immersion in the ocean in interglacial times. The model is used to gauge the impact of potential anthropogenic warming in the deep future, driven by changes in water temperature and sea level. PERGAMON meeting: 5-7 November 2013; GEOMAR, Kiel, Germany 34 Posters PERGAMON meeting: 5-7 November 2013; GEOMAR, Kiel, Germany 35 Experimental study of methane emission in frozen sediments under porous gas hydrates dissociation. Chuvilin E.M., Bukhanov B.A., Tkacheva E.V., Ekimova V.V. Department of Geology Moscow State University Leninskie Gory, Moscow, 119991 RUSSIA The results of experimental modeling of methane emission in frozen hydrate saturated sediments samples under decrease of gas pressure below the equilibrium and increase of the temperature are presented in report. Sand samples collected during the drilling of the upper layers of Laptev Sea shelf permafrost have been used as an object of investigations. A special experimental cell was used for preparation of frozen hydrate saturated sand samples and for study of the kinetic of porous gas hydrate dissociation under negative temperatures (Chuvilin, Guryeva, 2009). The experimental data on the methane emission in artificial hydrate saturated sand samples under the pressure below the equilibrium have been received during the experiments. It is shown that the relative methane emission due to porous hydrate dissociation can reach more than 10 m3 per m3 of gas hydrate content sediment. It is found that the methane emission in the hydrate saturated frozen sand samples under pressure decrease and temperature -2,5°C and below has a fading character through the self-preservation of porous gas hydrates and formation of metastable inter permafrost inclusions. It is noted that the additional methane emissions due to gas hydrate decomposition under heating of conserved gas hydrate formations in frozen sediment taken place. It is shown that the relative methane emission under decomposition of gas hydrate self-preserved into frozen sediment can reach more than 4 m3 per m3 of thawing gas hydrate sediment. The decomposition process due to heating of the frozen sediment containing self-preserved gas hydrate begins and ends earlier than the pore ice is thawing. This temperature shift increases with increasing of water-soluble salts content in the sediment. PERGAMON meeting: 5-7 November 2013; GEOMAR, Kiel, Germany 36 Planned measurement activities in MOCA (Methane Emissions from the Arctic Ocean to the Atmosphere: Present and Future Climate Effects) Adam Durant 1, Cathrine Lund-Myhre 1, Jürgen Mienert 2, Andreas Stohl 1, Ignacio Pisso 1 1Norwegian Institute for Air Research, Kjeller, Norway 2CAGE -Centre for Arctic Gas Hydrate, Enviroment and Climate, UiTThe Arctic University of Norway, Tromsø, Norway Methane hydrates (MH) in ocean seabed sediments are a potential source of methane (CH4) to the atmosphere, where CH4 has potential to act as a powerful greenhouse gas. However, current scientific results show diversity in the flux of CH4 that actually reaches the atmosphere. MH are potentially susceptible to ocean warming, which could trigger a positive feedback resulting in rapid climate warming. MOCA is a new project funded by the Norwegian Research Council that will apply advanced measurements and modelling to quantify the amount and present atmospheric impact of CH4 originating from MH. Furthermore, the project will investigate potential future climate effects from destabilisation of MH deposits in a warming climate, and will focus on scenarios in 2050 and 2100. The project partners include the Norwegian Institute for Air Research, the Centre for Arctic Gas Hydrate, Environment and Climate (CAGE) at UiTThe Arctic University of Norway in Tromsø, and the Centre for International Climate and Environmental Research in Oslo. External partners include Helmholtz Centre for Ocean Research (GEOMAR); Royal Holloway University, UK; Laboratoire des Sciences du Climat et l'Environnement, France; Russian Academy of Sciences, Russia; University of Cambridge, UK; U.S. Geological Survey, USA; Deutsches Zentrum für Luft- und Raumfahrt, Germany; and University of Bern, Switzerland. MOCA will combine land-, ship- and aircraft-based measurements in Work Package 1 (WP1) in coordinated campaigns to improve the description of the current environmental state of MH in the Svalbard region. Measurement and modelling activities will quantify the present-day CH4 emissions from marine seep sites west of Prince Carl Forland to the atmosphere, and will identify the main influences on the atmospheric fraction. Key activities will include: • Determination of seabed-ocean methane fluxes from in situ seabed measurements (MASOX landers and accompanying buoys with measurement instrumentation) targeting CH4 bubble release area offshore from Prins Karls Forland. • Determination of the atmospheric gas fraction from MH dissociation through ocean column profile sampling for dissolved and gaseous CH4, and measurement of ocean-atmosphere interface CH4 fluxes and isotope abundances. • Extended time-series measurements of atmospheric CH4 (including in situ CH4 mixing ratios and isotope abundances) at Zeppelin Observatory. • Aircraft-based vertical profiles of CH4 concentration and isotope abundances over the ocean around Svalbard and Siberia. PERGAMON meeting: 5-7 November 2013; GEOMAR, Kiel, Germany 37 The project is anticipated to generate new knowledge on the entire Earth system and climate change using the region around Svalbard as an experimental test bed to study polar processes. Modeling degradation of subsea permafrost in the near-shore zone of the Laptev Sea shelf F. Kneier, M. Langer, P.P. Overduin After the last glacial period, rising sea levels covered large areas of terrestrial permafrost with sea water and created the subsea permafrost present today on the arctic continental shelves. After inundation, the degradation of permafrost is governed by the influence of sea-bottom temperatures, salt infiltration into the flooded sediment and a suite of near-shore coastal processes. Subsea permafrost warming can release trapped methane to the atmosphere and affect coastal erosion rates. Our objectives are to employ meso-scale numerical calculations (from meter to kilometer spatial scales and up to 1000s of years temporal scale) in connection with borehole data from the Laptev Sea to model the transition of permafrost from onshore to offshore conditions. The goal is to identify key processes driving permafrost degradation in the near-shore zone of the shelf and to include quantitative parameterizations based on field observations in the models. Heat transfer is solved numerically and takes freeze-thaw processes into account in a three-phase heat capacity / conductivity model. Sediment composition and initial temperature profiles are derived from field and laboratory analysis of the borehole data. Our approach includes the effect of pore water salinity on phase state and thermal properties in order to show the impact of solute transport mechanisms into the sediment. Measured permafrost temperatures along a borehole transect that extends from an onshore borehole to an offshore borehole that flooded roughly 2500 years ago are compared to the modeled subsea soil temperature evolution following transgression. The degradation of the ice-bearing permafrost table or thaw depth is of special interest due to its direct relation to sediment stability and as the most readily discernible feature in the field observations. This thaw depth is mainly driven by salt contamination and modeled salinity profiles for the different transport mechanisms are compared to profiles from arctic shelf drill sites. PERGAMON meeting: 5-7 November 2013; GEOMAR, Kiel, Germany 38 Gas hydrate on the West Greenland shelf indicated by BSR and shallow sub-seafloor study Laier,T, Nielsen,T, Kuijpers,A, Nørregård-Pedersen,N, & Mikkelsen,N.E Geological Survey of Denmark and Greenland (GEUS). tl@geus.dk A BSR (bottom simulating reflector) was noted c. 70 m bsfl on a conventional seismic profile acquired in 1995 approximately 150 km SW of Disko Island. The presence of a gas hydrate is the most likely explanation for the BSR. Gas hydrate is potentially unstable in this region which is likely to be most affected by future climate warming. Various onshore studies are already being carried out on the Disko Island in order to study the effect of climate warming on gas emissions (CO2, CH4, and N2O), so for obvious reasons it was decided to initiate studies on the presumed gas hydrate in the region. A pilot study was carried out including gravity coring (6 m) and shallow seismic profiling using a sparker seismic source. The area above the BSR is a c. 60 m deep seafloor depression covered by up to c. 30 m of Late Pleistocene sediments consisting of two acoustically distinct units, a c.10 m thick stratified unit below a transparent layer, which vary in thickness. The transparent layer wedges out at edge of the seafloor depression. Seismic blanking resulting from acoustic scattering was observed on numerous occasions in the stratified layer forming plumes, which could indicate gas migrating from below. However, methane analysis did not indicate any major advection of high methane fluids from below, methane varying from 0.02 to 0.06 mM in four out of five cores. It is possible though that methane from below has been removed to a large extend by anoxic oxidation coupled to sulphate reduction since sulphate concentration was 5-10 mM in the deepest pore water. The low organic matter content (TOC<0.5%) in the sediment of the four cores together with the almost linear in decrease sulphate with increasing depth indicate that methane was the major substrate for sulphate reduction. Although methane was low in the four cores it is still 10-30 times higher compared to other organic lean sediments containing sulphate pore waters. We speculate that the plume like features seen in the stratified layer may be due to gas filled micro-channels which allows methane to diffuse rapidly to shallow levels before being dissolved and oxidized. Higher methane up to 1.5 mM was found in the fifth core taken in a pockmark with acoustic blanking seen below. This core which penetrated the sulphate methane transition zone four metres below seafloor had higher organic matter content which may have generated at least some the methane found. However, the methane concentration profile with depth leaves little doubt that more active gas migration occurs at this location. BSRs reflect the transition from free gas to solid hydrate at the base of the gas hydrate stability zone (GHSZ). Given the water depth (490-560 m) of our studied area and the general bottom water temperature (4 °C) in the area, one should expect to find the base of GHSZ at approximately 100 m bsfl, as was observed. PERGAMON meeting: 5-7 November 2013; GEOMAR, Kiel, Germany 39 Methane in high latitudes and assessing its climate impact: Towards an integrated research approach I.D. Streletskaya, B.G. Vanshtein1, A.A. Vasiliev2, Lomonosov Moscow State University, Department of Geography, 119991, Moscow, Leninskie Gory 1, Russia, irinastrelets@gmail.com 1VNIIOkeangeologia, 190121 St. Petersburg Angliyskii pr. 1, Russia; vanshbor@mail.ru 2Earth Cryosphere Institute SB RAS, 625000, Tyumen, p/o box 1230, Russia; al.a.vasiliev@gmail.com Presented and discussed the new data of gas properties (total gas content and composition) and water stable isotopes of two climatically contrasted Holocene and Pleistocene syngenetic ice wedges (SIW) and two types of tabular massive ground ice (TMGI) near Marre-Sale polar station, West Yamal, Russia. Our data set also supports the previous assumption that the ice wedges with isotopic signature (-25-23ppm for 18O and -190-180ppm for D) were formed in Pleistocene winters and the ice wedges with isotopic signature (-17-15ppm for 18O and -118- 114ppm for D) in Holocene. For carbon dioxide, all ice wedges mixing ratios are clearly higher than the atmospheric values (0,03pct), the highest values being observed in Pleistocene ice wedges (0,97 pct), in Holocene ice wedges - (0,64 pct). Oxygen shows consistently lower values than the atmosphere (of the order of 4-7 pct), and nitrogen is slightly higher, balancing other constituents. On the contrary, methane mixing ratios show their lowest values in Pleistocene SIW (0, 004%), in Holocene SIW - (0,164 pct). Air bubbles trapped in polar ice provide an almost direct record of atmospheric methane over the last 800 kyr (e.g., Loulergue et al., 2008), methane budget for the periods is known: present (0,167 pct), and Last Glacial Maximum (0,036) (e.g., Josueґ Bock et al., 2012) and it is comparable with our data. Different methane mixing ratios in SIW suggest different climatic and environmental conditions. These properties are consistent with SIW developing under relatively warm Holocene conditions and cold in Pleistocene. Methane mixing ratios in TMGI show highest content (till 1, 37 pct). Isotopic measurements of the 13C -70,5ppm, and D -326ppm in methane are typical for gas formed with the participation of vital functions of bacteria. Found that the isotopic values 13C in methane are close to the values of the carbon isotopes of methane horizons at depths of 46-52 and 114-120 m in the Bovanenkovo gas field, West Yamal, and characterized of isotope volume -70,4-76,8ppm. Source of methane in TMGI could not be methane hydrates, because methane hydrates have a specific deuterium isotopic signature of about -190ppm, versus about -290ppm for mean of other sources. This pilot study detailed gas content and composition, and water and gas isotope analyses of ground ice sheds more light on the conditions of ground ice growth under changing environmental conditions. Higher temperatures in a Holocene resulted higher methane content in SIW, relatively high carbon dioxide levels. Lower temperatures in a Late Pleistocene resulted lower methane content in SIW. PERGAMON meeting: 5-7 November 2013; GEOMAR, Kiel, Germany 40 It is difficult to select potential sources bubbles trapped gas in TMGI. This heterogeneous medium, rich in organic matter, might have favored the anaerobic microenvironmental conditions necessary to explain the maximum methane content levels. Marshy coasts near shallow seas may have contributed to such conditions. The content of marsh gas in TMGI excludes their glacial origin. Using noble gases in the pore water of ocean sediments to characterize methane seepage off the coast of New Zealand Yama Tomonaga1, Matthias S. Brennwald1, and Rolf Kipfer1,2,3 1Eawag, Swiss Federal Institute of Aquatic Science and Technology, Department of Water Resources and Drinking Water, CH-8600 Dübendorf, Switzerland 2Institute of Biogeochemistry and Pollutant Dynamics, Swiss Federal Institute of Technology (ETH), CH-8092 Zurich, Switzerland 3Institute of Geochemistry and Petrology, Swiss Federal Institute of Technology (ETH), CH-8092 Zurich, Switzerland Newly developed analytical techniques to determine the abundances of noble gases in sediment pore water allow noble-gas concentrations and isotope ratios to be measured easily and routinely in unconsolidated lacustrine sediments. We applied these techniques for the first time to ocean sediments to investigate an active cold methane seepage system located in the South Pacific off the coast of New Zealand using 3He/4He ratios determined in the sediment pore water. Our results show that more 3He-rich fluids are released in the vicinity of the Pacific- Australian subduction zone than at the forearc stations located closer to the New Zealand coast. However, the 3He/4He isotope signature in the sediment column indicates that only a minor part of the He emanating from deeper strata originates from a (depleted) mantle source. Hence, most He in the pore water is produced locally by the radioactive decay of U and Th in the sediment minerals or in the underlying crustal rocks. Such an occurrence of isotopically heavy crustal He also suggests that the source of the largest fraction of methane is a near-surface geochemical reservoir. This finding is in line with a previous d13C study in the water column which concluded that the emanating methane is most likely of biological origin and is formed in the upper few meters of the sediment column. The prevalence of isotopically heavy He agrees well with the outcome of other previous studies on island arc systems which indicate that the forearc regions are characterized by crustal He emission, whereas the volcanic arc region is characterized by the presence of mantle He associated with rising magma. PERGAMON meeting: 5-7 November 2013; GEOMAR, Kiel, Germany 41 SUBMARINE PERMAFROST OF KARA SEA: ACTUAL VIEW Vasiliev1, G. Oblogov1, P. Rekant2 1Earth Cryosphere Institute SB RAS, Tyumen, Russia, 2 All Russian Institute of Ocean Geology and Mineral Resources, St. –Petersburg, Russia According to the modern understanding, submarine permafrost (SMP) in the Kara Sea shelf can be encountered in the area from the coastline up to the water depth of 120 m, which corresponds to decrease in the sea level during the Sartan cryochron (last glacial maximum of the Late Pleistocene). Potential depth of freezing and corresponding SMP thickness could reach 400 to 500 m. Thus, one can presume that SMP in the study area is relic. However, during the drilling in the deep-marine shelf of the south-east part of the Barents Sea, SMP bodies shaped like ice stocks whose thickness exceeded 100 m and whose temperature was constant with depth were encountered. It was presumed that their formation occurred as a result of rapid degassing and overcooling of initially unfrozen gas-saturated sediments with temperatures close to the freezing temperature. So, SMP of the continental shelf of the Kara and Barents Seas is represented by both relic and newly formed permafrost. Besides, modern permafrost formation occurs at low accumulative surfaces (e.g. Sharapovy and Marre-Sal’skiye Koshki). Under conditions of lack of direct information on SMP (i.e. drilling data), indirect methods of permafrost detection in shelf deposits become extremely important. The most promising method is a high-resolution seismo-acoustic profiling. This recently developed method now is included in a standard set of methods of oceanological research, and a large data base on seismo-acoustic measurements in the whole Kara Sea area has been accumulated. The main obstacle in application of the highresolution seismo-acoustic profiling for SMP identification is related to extremely high gas saturation of the Quaternary deposits within the shelf. Never the less, new methods of the data processing allow detecting of acoustic reflectors which can be interpreted as a permafrost table. Verification of results of seismo-acoustic profiling basing on their comparison with the drilling data was performed in the area of relatively shallow-water continental shelf near Kharasavey and showed a sufficient correlation. All available results of seismo-acoustic profiling obtained by various institutions have been collected. More than 130,000 km of profiles have been analyzed and interpreted. Within 30,000 km of profiles, acoustic reflectors which can be interpreted as a permafrost table have been detected. The information on coordinates, sea depth, and permafrost table depth was arranged in a data base which contains approximately 30,000 records on SMP table locations in the seismo-acoustic profiles. A map of SMP distribution of Kara Sea was developed basing on GIS-technology. This map can be updated with adding of the new data of seismo-acoustic profiling. Thus, it always represents a current level of our knowledge of SMP. PERGAMON meeting: 5-7 November 2013; GEOMAR, Kiel, Germany 42 More than three thousand years of microbial methane consumption at cold seeps offshore Svalbard Irina Vögtli1, Lea Steinle1,2,*, Volker Liebetrau2, Stefan Krause2, Moritz Lehmann1, Tina Treude2, Helge Niemann1 1University of Basel, Dept. of Environmental Geosciences, CH (corresponding author: lea.steinle@unibas.ch) 2GEOMAR, Helmholtz Centre for Ocean Research, D Microbial consumption retains a significant fraction of methane in marine sediments. Under anoxic conditions, anaerobic oxidation of methane (AOM) is mediated by archaea with sulfate as the terminal electron acceptor. When oxygen is available, methane can be consumed in a bacterial process termed aerobic oxidation of methane (MOx). The latter process is typically less important because O2 availability in s is very low. However, in the case of cold seeps, MOx can play a more significant role since the strong methane flux in these systems can bypass the AOM filter in deeper sediments. At present, numerous point sources emit methane from the sea floor at cold seeps offshore Svalbard but the temporal dynamics of the seepage are not well constrained. On an expedition with R/V M.S. Merian (MSM 21/4) in 2012, we sampled recent sediments and more than three thousand year old authigenic carbonate accretions in the direct vicinity of bubble release sites at 386m water depth with the submersible JAGO. The composition of lipid biomarkers and their associated stable carbon isotope values provide evidence for distinctly different methanotrophic communities in recent sediments and carbonates. In recent sediments, the dominance of the 13C-depleted archaeal biomarker archaeol and the absence of sn2- hydroxyarchaeol and crocetane point at an ANME1 archaea dominated AOM community in deeper sediments (~5 cm bsf). In accordance with our visual observations, a fraction of the methane flux by-passes the AOM filter and is consumed by MOx communities in surface sediments, as indicated by the presence of the 13C-depleted 4α-methylsteroids and diploptene. In contrast to the sediments, carbonates contained archaeol, as well as substantial amounts of sn2- hydroxyarchaeol and crocetane, suggesting a dominant role of ANME2 in the AOM community at the time of carbonate precipitation, and therefore a community shift at some point of time with respect to current conditions. Similar to sediments, we also found 4α-methylsteroids and diploptene suggesting a close proximity of AOM and MOx communities and a strong methane flux since several millennia at the Svalbard cold seeps.

• Добавил в систему: Стрелецкая Ирина Дмитриевна

Доклады:

• 2013 Gas properties of the ground ice as a proxy of climatic and environmental conditions in West Arctic (Устный)
• Авторы: Streletskaya I.D., Vasiliev A.A., Vanshtein B.G.