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Analytical Chemistry and Permafrost T
his Editorial was inspired by a bus driver who awakened my vacationing and happily sleeping neurons on a road to Fairbanks, Alaska. First, he announced, “Get ready for frost heaves—a bumpy ride,” and later, following the bumps, he said, “Ah! The smooth new road.” Tim “The Driver” explained that the new road was insulated from the heaving freeze–thaw cycles of underlying permafrost by thermal foam insulation. The insulation protects the permafrost from the warmth of the road, not the reverse. Likewise, buildings may be built on stilts to avoid melting the permafrost, which can cause buildings to subside. The Trans-Alaska Pipeline is elevated for the same reason; in the places where it is buried, it may be cooled by refrigerator coils. (Imagine the need for refrigeration outdoors in Alaska!) An ensuing visit to the University of Alaska, Fairbanks, its Museum of the North, and its International Arctic Research Center whetted my interest in learning more about permafrost and its analytical chemistry. Permafrost underlies ~24% of the terrestrial Northern Hemisphere—that’s a large area. It consists of an upper seasonal freeze–thaw (“active”) layer and a lower permanently frozen soil–ice layer that can be quite deep—1500 m at one location in Siberia. Coping with permafrost has a profound influence on the infrastructure of human activities in cold climates, including roads, rails, airports, buildings, and pipelines. Because higher soil temperatures cause thickening of the active layer and thinning of the permanent layer, measuring changes in the geographical distribution of permafrost is useful in monitoring climate change. Thickened active layers also enhance the release of CO2 because of microbial activity in the soil. The 2003 report Climate Change, Permafrost, and Impacts on Civil Infrastructure by the U.S. Arctic Research Commission is informative reading about permafrost as a climatic archive and barometer. A random literature search for analytical chemistry measurements in permafrost investigations taught me that this is a large topic of applied analytical chemistry. Permafrost expels dissolved salts and can create saline water layers; consequently,
© 2005 AMERICAN CHEMICAL SOCIETY
measurements of ionic conductivity and of ion content by ion chromatography have become standard tools. Reflectance measurements are useful for estimating the water content of surface soil. Because permafrost is a barrier to surface draining, the content of surface water indicates the extent of subsurface permafrost. Mass spectrometric 18O isotope measurements are very important for hydrological applications, such as distinguishing “old water” that comes from melting hillside permafrost from “new water” (not enriched in 18O) that comes from melting snow. Heat and mass transfer are key measurement targets and formidable goals, given the spatial and chemical heterogeneity of mineral and soil organic overlayers. Permafrost has preserved samples of numerous ancient lifeforms, which have been used for MS-based sequencing comparisons to modern organisms. These are just a few examples. I hope this brief essay stimulates some thought in the analytical chemistry community about establishing collaborations with permafrost researchers aimed at further development of analytical tools, especially those that might close the gaps in data needed for climatic modeling. For example, remote optical imaging that provides information about water content and especially oxygen isotope content (maybe from vibrational spectra) would be valuable if it were possible. Analytical arrays that yield data about mass and heat transfer over millimeter-to-meter dimensions would aid modeling of the very heterogeneous problem of transfer through soil matrixes. Finally, I want to thank librarian Julia Triplehorn of the Geophysical Institute of the University of Alaska, Fairbanks, and Sergei Marchenko, a research scholar there who is visiting from the Kazakhstan Alpine Permafrost Laboratory of the Permafrost Institute of the Russian Academy of Sciences, for their kind reception during an unannounced visit to their offices. People of the Far North are genuinely friendly folk.
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