Hydrology in Permafrost Regions 173 Significance of isotope variations in permafrost waters at Illisarvik, N.W.T.
Analyses for '80 and 2H contents in permafrost cores from the Mackenzie River basin revealed very large depletions in the heavy isotope contents with depth. These shifts could be a reflection of decaying climatic conditions resulting in lower 180 and 2H contents in older ice or, under special c...
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| Language: | English |
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.557.4947 http://pubs.aina.ucalgary.ca/cpc/cpc4-173.pdf |
| Summary: | Analyses for '80 and 2H contents in permafrost cores from the Mackenzie River basin revealed very large depletions in the heavy isotope contents with depth. These shifts could be a reflection of decaying climatic conditions resulting in lower 180 and 2H contents in older ice or, under special circumstances, might be due to isotope fractionation processes occurring during freezing. Thus, as part of a detailed study of permafrost growth at the drained lake site known as Illisarvik on Richards Island in the Mackenzie Delta, a number of continuous cores were collected from within, and adjacent to, the lake bed. Water extracted from the samples by squeezing was analyzed for 180, ZH, and 3H isotopic contents in addition to conductivity. The soils were examined for grain size and moisture content, while organic-rich horizons were dated using the radiocarbon method. Radiocarbon dating of the lake-bed sediments indicate that the lake initially formed some 6700 to 8700 years ago. The I80 contents from the Illisarvik lake bed are in the range of-15 to-16 per mille near the surface, which are similar to the average lake water prior to drainage. Outside of the lake, 180 contents vary from-14 to-31 per mille. Tritium is confined to the active layer outside of the lake, while within the lake bed tritium occurs to a depth of 2 m. The results of this and other ongoing studies into the distribution of stable and radioactive isotopes occurring naturally in |
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