Action 902

1. Action 902 PERmafrost and GAs hydrate related methane release in the Arctic and impact on climate change: European cooperation for long-term MONitoring “PERGAMON” • Chair of the Action: • COST Science Officer: • Carine Petit, cpetit@cost.esf.org • Participating countries: Belgium, Denmark, France, Germany, Israel, Italy, Netherlands, • Norway, Spain, Sweden, Switzerland, United Kingdom WG-A: Methane formation, transport and accumulation in terrestrial and marine sediments and permafrost The Biogenic and thermogenic methane formation can be distinguished using a geochemical multi-parameter approach of the gas and isotopic composition. Quantification of reservoirs of methane: stored in the sub-seabed/sediment as gas hydrate and as free gas beneath the gas hydrate stability zone (GHSZ) and stored beneath the permafrost as gas hydrate and free gas is essential to estimate the future impact of methane escaping from them upon the global atmospheric methane concentration. Reservoir modelling of methane fluxes: State of the art reservoir modelling of methane fluxes, coupled dynamic to diffusive transport of methane through the ice layers above will be the primary theoretical model to be developed through scientific projects related to this Action. Seep detection and mapping: Where methane-charged fluids are expelled into the water column they form unique ecosystems (seeps or cold vents) and induce a large variety of specific bio-geochemical reactions. Barrow in North Alaska, one of the atmospheric monitoring sites. WG-B1: Biogeochemical processes in the shallow sub-seafloor and at the sediment-water interface Gas hydrate dissociation and methane transport: Conventional methods will be used to confirm gas hydrate presence in sediments and to estimate dissociation processes include temperature measurements, geochemical analyses (e.g. chloride, d18O, sulphate, porosity) and numerical reaction modelling. Microbial consumption of methane from dissociating gas hydrates. Anaerobic oxidation of methane (AOM) connected to sulphate reduction is commonly quantified by radiotracer techniques using 14C-labelled methane and 35S-labelled sulphate. Biogeochemical reactions resulting from methanotrophy in sediments (AOM leads to significant geochemical changes within the sediment. Of environmental importance is the release of hydrogen sulphide from sulphate reduction. Objectives: The main objective of this Action is to quantify the methane input from marine and terrestrial sources into the atmosphere in the Arctic region, and ultimately to evaluate the impact of Arctic methane seepage on global climate. This will be achieved by study of the origin and type of occurrence (dissolved/free gas, gas hydrate) of different methane sources (both on land and in the sub-seabed) as well as the methane migration mechanisms, biogeochemical turnover, release mechanism, and finally quantification of the flux into the atmosphere. Objective A: To determine the amount of methane (as free gas and gas hydrate) in the seabed and terrestrial permafrost by geophysical methods. To establish the role of tectonics, stratigraphy and sediment type in regulating gas hydrate and seep systems. Objective B: To improve understanding of the biogeochemical processes at the water-sediment interface and, at seep sites, to assess the control of benthic microbial communities on gas hydrate/methane systems and methane fluxes in particular. WG-B2: Effectiveness of methane transport through the water column (ocean and lakes) and assessment of methane fluxes into the atmosphere Dissolved and free gas fluxes: As methane is released into the water column either as dissolved or free gas (bubbles) both fluxes have to be quantified in two different approaches. Dissolved fluxes are modelled from geochemical gradients as outlined above. Free gas discharge can be measured directly by trapping bubbles, visually or hydroacoustic by lander systems, suitable for long-term monitoring. Bubble dissolution/gas stripping and atmospheric fluxes: To characterize the dissolution and stripping of rising gas bubbles through the water column, existing models are fine-tuned by analysing the gas composition of bubbles trapped in various height above the bottom and / or performing lab-experiments in counter-flow pressure chambers.

2. Action 902 PERmafrost and GAs hydrate related methane release in the Arctic and impact on climate change: European cooperation for long-term MONitoring “PERGAMON” • Chair of the Action: • COST Science Officer: • Carine Petit, cpetit@cost.esf.org • Participating countries: Belgium, Denmark, France, Germany, Israel, Italy, Netherlands, • Norway, Spain, Sweden, Switzerland, United Kingdom WG-C1: Methane fluxes from the terrestrial environment (wetlands, tundra, Arctic lakes) Quantification of methane fluxes from tundra environments: The quantification of methane fluxes from tundra environments and their seasonal variability provides the basis for a realistic budget of this important greenhouse gas. Methane in regions of the freshwater marine interface: In estuaries, zones of high methane concentrations and zones of high oxidation rates have to be located for an assessment of sinks and sources. Coastal melt water and water from eroding coasts are of major interest as primary modulators of methane fluxes. Objectives: Objective C: To investigate the physical and chemical dynamics of methane hydrate formation and decomposition on land and in the ocean and to use this knowledge to determine how fast, and under which future warming scenarios, gas hydrate will decompose. Objective D: To quantify methane fluxes from the seabed into the water column, and from the water column into the atmosphere, and to assess the physical and biochemical controls on the fate of methane in the ocean. Objective E: To quantify the methane flux into the atmosphere from tundra at the present-day, and to predict how this flux might vary in the future. Objective F: To monitor the seasonal and isotopic variability of Arctic methane, as shown by time series of concentration and C isotopic ratio; assess sources by field campaigns and trajectory analyses, as well as by satellite retrievals. Objective G: To integrate geochemical, sedimentological, geophysical, oceanographic and (micro)biological data for quantitative model testing of the different sub-systems and the overall integrated methane fluxes in the Arctic. Objective H: To develop new tools, methodologies and approaches that will enable Action partners to better understand the processes that regulate the Arctic methane system. Objective I: Publish the scientific results in high ranked international journals. The compilation of Special Issues about certain topics (e.g. compiling results from research cruises to the same area; compiling flux papers from on- and offshore with remote sensing results) is aimed for. WG-C2: Remote and land-based atmospheric methane monitoring Methane is continuously monitored in the Arctic at several stations, especially Barrow, Alert, Pallas and Ny Alesund. The data can be used for trajectory analysis. In addition, a number of flask collection programs exist. The key to identification of sources is isotopic monitoring, but at present the only long-extended time series is from Alert. Recently, new flask and bag sample programmes have been started. Continuous monitoring from additional tower sites (integrated with ICOS) in conjunction with aircraft programs could help reconcile top down inverse modelling and bottom up inventory or process modelling techniques to improve our spatial and temporal quantification and assessment of climate driven changes in methane exchange. WG-D: Datacompilation, integration and organization of data distribution among the scientific community This WG will also provide the PERGAMON Web-interface and includes the Web-coordinator responsible for the Action web site Bubble release offshore Svalbard. For the first time, methane bubbles has been visually detected in this area in July 2009 during a cruise with RV Jan Mayen at 240m water depth (image to the right) Using hydroacoustic methods (fish finding sonars) allows to identify bubble release from the seafloor (image below). The detected signals can be directly linked to bubble release and sophisticated processing allows even for quantitative estimates of the amount of gas being released as well as for bubble dissolution and the final transport of methane into the atmosphere.