Stream Water Analysis Helps in Assessment of Permafrost Thaw
07.05.2010 - Atmosphere & Space, Land & Geology, Ice & Snow, Arctic
Monitoring changes in permafrost is difficult using current methods. Fortunately, researchers from the University of Michigan have developed a new approach based on the use of chemical tracers in stream water.
Their results, published recently in the journal Chemical Geology, gives various assessments through physical measurements and models, which suggest that the active layer thickness of the permafrost (the part that unfreezes and urfreezes every year) has increased over the 20th century, with a further possible increase of up to 40% by the end of the 21st century. Although the full extent of future impacts still has to be assessed, several structures built on permafrost will certainly suffer serious damage, whilst the release of methane and other greenhouse gasses will continue to increase.
Whilst they were studying the chemistry of soils in northern Alaska, the team also found that the chemistry of the soil changed dramatically once they got below the thickness that typically thaws in the summer months. For example, elements such as calcium, sodium and barium, are present in a much higher concentrations in the newly-thawed permafrost.
The researchers then studied whether these chemical features could also be found in local stream water. After analyzing samples collected over an 11-year period, the team found very significant year-to-year changes that were consistent with what could be predicted from increasing thaw depths. Although the method can not reveal the precise amount of permafrost thawing in particular localities, it could be a useful adjunct to current methods.
