Page 149 - Microbial methane cycling in a warming world From biosphere to atmosphere Michiel H in t Zandt

Wetland - An ecosystem that is temporarily or permanently flooded with water, causing anoxic sediment conditions.
Yedoma - Ice-rich permafrost with an organic matter content between 2% and 5%.
Outstanding questions
• Thermokarst lakes are transient environments that are features of permafrost thaw. How can their greenhouse gas releases be best incorporated into climate models and temperature scenarios? Which data need to be generated by biogeochemists and microbiologists to be useful for climate scenario development?
• Thermokarst lakes are highly variable environments with regard to hydrological changes, sea
water influence, carbon bioavailability, and other physicochemical parameters. Which molecular proxies can be used to estimate greenhouse gas fluxes, or to categorize thermokarst
lakes with regard to their greenhouse gas emission potential? Which factors determine the type 6 of methanogenesis and methanotrophy pathways?
• Most GHG flux data are collected during the summer months, due to difficulties in accessing the area and measuring fluxes in a frozen landscape. What are the year-round greenhouse gas emissions from thermokarst lakes? How are microbial processes changing during winter, under the ice cover of these lakes? How do these processes change with different types of thermokarst lake landscapes?
• Which are the microbial key players in methane production and methane oxidation? Are current molecular methods adequate for the detection of all relevant players?
• Do anaerobic methanotrophic archaea contribute to mitigation of methane emissions? Which physicochemical parameters govern the type of anaerobic/aerobic methane oxidation in thermokarst environments?
• The temperature sensitivity of an ecosystem is determined by geochemical and biological parameters. How can we best implement these parameters to improve Q10 values of thermokarst environments?
• Nitrous oxide (N2O) has an even higher global warming potential than CO2 and CH4. Do thermokarst lakes, specifically those with high organic nitrogen concentrations and the presence of ANME-2d archaea, also contribute to N2O emissions?
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