To the Core
We have spent the entire week refining our skills at various tundra study sites by digging random soil pits to collect samples at various depths, depending upon the organic layer thickness. Adjacent to each pit, we measured out a 1.5m x 1.5m survey quadrat and inspected the characteristics of all seedlings or saplings present. We have dutifully collected our data sets, both in the field and in the lab. However, today we discovered the Team would take its climate change studies to a much deeper level. 
We investigated a pair of study sights called the polygonal peat plateau aggrading (PPA) and the polygonal peat plateau degrading (PPD). Aggrading means the permafrost is either stable or accumulating annually, degrading means that the permafrost layer is diminishing. Polygonal peat plateaus [see photo above] are perennially frozen bogs that rise approximate lm or more above the surrounding fen. The surface of the plateau is relatively flat and is scored by a polygonal pattern of trenches that developed from repetitive ice wedges.
In addition, soil pits were also dug in the centers of surrounding plateaus. Polygon centers are thought to be the least active area and hence should contain the oldest most chemically developed soil. One of our goals is to determine the chemical relationship between the active layer soil and ice-cemented sediments. The active layer is a surface layer of earth materials above the permafrost layer that thaws and refreezes on an annual basis. Remember that permafrost can be either rock or soil that remains below 0°C for at least two years. Entombed in that freezer is carbon, plant and animal matter accumulated through millennia. Permafrost thickness is related to the air temperature and soil characteristics. Surface conditions including vegetation, organic cover and snow thickness can also influence permafrost temperatures.
Overall we are interested in describing the carbon dynamics of the peatlands in this area. As the soil thaws, ancient deposits decompose, attacked by microbes, producing carbon dioxide and, if in water, methane. Both are greenhouse gases, but methane is many times more powerful in warming the atmosphere. Methane also is present in another form, as hydrates, ice-like formations deep underground and under the seabed in which methane molecules are trapped within crystals of frozen water. If warmed, the methane will also escape.
Recent loss of permafrost has caused peatlands to subside into the much wetter surrounding wetland, with changes in vegetation and greenhouse gas emissions as a result. Keep in mind that once permafrost is lost, it is not likely to come back in the foreseeable future. Climate researchers like Dr. Peter Kershaw calculate that the top 10 feet of permafrost alone contain more carbon than is currently in the atmosphere. "It's safe to say the surface permafrost, 3 to 5 meters, is at risk of thawing in the next 100 years," says Kershaw. Aside from possible effects on the global carbon cycle, this also means that if the frozen peatlands of Churchill disappear, along with them species of plants and birds of this habitat will also be in jeopardy.
How’s this for an application question of what was just discussed: As the permafrost layer continues to thaw, what organic substance might you expect to find in higher quantities in the soil of the active layer? What evidence do you have to support your answer?
We investigated a pair of study sights called the polygonal peat plateau aggrading (PPA) and the polygonal peat plateau degrading (PPD). Aggrading means the permafrost is either stable or accumulating annually, degrading means that the permafrost layer is diminishing. Polygonal peat plateaus [see photo above] are perennially frozen bogs that rise approximate lm or more above the surrounding fen. The surface of the plateau is relatively flat and is scored by a polygonal pattern of trenches that developed from repetitive ice wedges.
In addition, soil pits were also dug in the centers of surrounding plateaus. Polygon centers are thought to be the least active area and hence should contain the oldest most chemically developed soil. One of our goals is to determine the chemical relationship between the active layer soil and ice-cemented sediments. The active layer is a surface layer of earth materials above the permafrost layer that thaws and refreezes on an annual basis. Remember that permafrost can be either rock or soil that remains below 0°C for at least two years. Entombed in that freezer is carbon, plant and animal matter accumulated through millennia. Permafrost thickness is related to the air temperature and soil characteristics. Surface conditions including vegetation, organic cover and snow thickness can also influence permafrost temperatures.
Overall we are interested in describing the carbon dynamics of the peatlands in this area. As the soil thaws, ancient deposits decompose, attacked by microbes, producing carbon dioxide and, if in water, methane. Both are greenhouse gases, but methane is many times more powerful in warming the atmosphere. Methane also is present in another form, as hydrates, ice-like formations deep underground and under the seabed in which methane molecules are trapped within crystals of frozen water. If warmed, the methane will also escape.
Recent loss of permafrost has caused peatlands to subside into the much wetter surrounding wetland, with changes in vegetation and greenhouse gas emissions as a result. Keep in mind that once permafrost is lost, it is not likely to come back in the foreseeable future. Climate researchers like Dr. Peter Kershaw calculate that the top 10 feet of permafrost alone contain more carbon than is currently in the atmosphere. "It's safe to say the surface permafrost, 3 to 5 meters, is at risk of thawing in the next 100 years," says Kershaw. Aside from possible effects on the global carbon cycle, this also means that if the frozen peatlands of Churchill disappear, along with them species of plants and birds of this habitat will also be in jeopardy.
How’s this for an application question of what was just discussed: As the permafrost layer continues to thaw, what organic substance might you expect to find in higher quantities in the soil of the active layer? What evidence do you have to support your answer?
Labels: active layer, methane, polygonal peat plateau
posted by Chris Bobkowski @ 10:55 PM
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