Permafrost Microbial Action
There are an estimated 1,7 billion metric tons of carbon in the frozen soils at the north pole. This sequestered carbon is more than 250 times the amount of greenhouse gas emissions attributed to the United States in the year 2009. As global temperatures slowly rise, however, so too do concerns regarding the potential impacts upon the carbon cycle when the permafrost thaws and releases the carbon that has been trapped for eons. In this case the concern focus on the microbes in the permafrost that will ultimately release, contain, or somewhere in between limit the carbon release.
In geology, permafrost, cryotic soil or permafrost soil is soil at or below the freezing point of water (0 °C or 32 °F) for two or more years. Ice is not always present, as may be in the case of nonporous bedrock, but it frequently occurs and it may be in amounts exceeding the potential hydraulic saturation of the ground material. Most permafrost is located in high latitudes (i.e. land close to the North and South poles), but alpine permafrost may exist at high altitudes in much lower latitudes. Permafrost accounts for 0.022% of total water and exists in 24% of exposed land in the Northern Hemisphere.
Map showing extent and types of permafrost in the Northern Hemisphere
The extent of permafrost can vary as the climate changes. Today, a considerable area of the Arctic is covered by permafrost (including discontinuous permafrost). Overlying permafrost is a thin active layer that seasonally thaws during the summer.
Among the new findings, published online November 6 in the journal Nature, is the draft genome of a novel microbe that produces methane, a far more potent greenhouse gas than carbon dioxide. This microbe, not yet named, lives in the permafrost, and was assembled out of the collection of genomes—the metagenome—isolated from the frigid soil. The assembly challenge is similar to building one complete jigsaw puzzle from a large collection of pieces from many different puzzles.
"The permafrost is poised to become a major source of greenhouse gases as the temperature in the Arctic is expected to increase dramatically compared to the expected temperature increase in many other regions of the world," said ESD's Janet Jansson, corresponding author and initiator of the study (first supported by a grant to her from DOE Laboratory Directed Research and Development funds). "By applying metagenomics to study microbial community composition and function, we can help to answer questions about how the currently uncultivated and unstudied microbial species residing in permafrost cycle organic carbon and release greenhouse gases during thaw," Jansson said. "This will provide valuable information that could lead to improved carbon cycle models and eventual mitigation strategies."
According to the U.S. Environmental Protection Agency, in 2009 fossil fuel combustion accounted for 5.2 billion metric tons of the nation's carbon dioxide emissions, a tiny fraction (about 3/10 of 1 percent) of the carbon dioxide trapped in the Arctic permafrost. Understanding the microbial processes in the frozen soils and the impacts of microbial activity on carbon dioxide processes, has been a project of study co-author and USGS researcher Mark Waldrop, whose 2010 Community Sequencing Program project, another with the DOE JGI (in collaboration with Jansson), focuses on comparing the short-term microbial response of the thawing permafrost to the longer-term processes.
For further information: http://www.physorg.com/news/2011-11-arctic-microbes-world.html