C. Hillaire-Marcel Departement Sciences de la Terre, Universite du Quebec a Montreal
Meromictic Lakes Garrow and Sophia in the Canadian Arctic Archipelago were sampled to establish the origin and age of their waters by isotopic studies. The?&,OW*8O values reflect the permanent stratification of the waters in both lakes. The mixolimnia contain waters with an isotopic signal betwe...
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| Language: | English |
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.507.1864 http://www.aslo.org/lo/toc/vol_29/issue_3/0564.pdf |
| Summary: | Meromictic Lakes Garrow and Sophia in the Canadian Arctic Archipelago were sampled to establish the origin and age of their waters by isotopic studies. The?&,OW*8O values reflect the permanent stratification of the waters in both lakes. The mixolimnia contain waters with an isotopic signal between- 13.16 and- 2 1.98o/oo, coherent with the values for precipitation in these high latitudes. The short residence time of the water in this layer makes it possible to record episodic variations of the freshwater inputs to the lakes. In the chemoclines, the Al80 values increase to- 10 % concomitantly with a rise in chloride content to 42 g-liter-‘. This corresponds to a con-servative mixing of surficial and deep waters. In the monimolimnia, hypersaline waters (up to 2.5 times the salinity of seawater) show negative 6180 values (ca.- 8%~). These waters result from brine production during permafrost growth in the watershed, according to a Rayleigh process. The brines drained toward the deepest part of each lake, after postglacial uplift, and became isolated. 14C dating of total inorganic carbon in the Lake Garrow monimolimnion gave an age of 2,580 + 260 years B.P. In Lake Sophia, the deep waters exhibit recent 14C activity (12 1.4 % modern carbon) that suggests recent infiltration of seawater into the lake basin. Three main mechanisms have been cited to explain the development of meromixis in lake basins (Walker and Likens 1975): advection of saline waters in deep parts of coastal lakes (ectogenic meromixis); infil-tration of saline groundwater under the in-fluence of local hydraulic head (crenogenic meromixis); organic production and accu-mulation of catabolic salts (biogenic mero-mixis). Dickman and Ouellet (unpubl., 1983) re-cently studied two meromictic lakes in the |
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