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Interpretation of oxygen and sulfur isotopes from dissolved sulfates in tills of southern Alberta, Canada

Journal Article · · Water Resources Research; (USA)
 [1]; ;  [2]
  1. National Water Well Association, Dublin, OH (USA)
  2. Univ. of Calgary, Alberta (Canada)

Tills of the Interior Plains Region of southern Alberta, Canada, consist of an upper sulfate-rich weathered zone and a lower sulfate-deficient nonweathered zone. The {delta}{sup 18}O of aqueous sulfate from the nonweathered zone was enriched over the {delta}{sup 18}O of the weathered zone however. The {delta}{sup 18}O and {delta}{sup 34}S data from the aqueous sulfate provide independent support for an earlier finding that most sulfate in the weathered zone is derived from the oxidation of reduced sulfur. The {delta}{sup 18}O of aqueous sulfate from the nonweathered zone is different from that of the associated ground waters, whereas the {delta}{sup 18}O of aqueous sulfate from the weathered zone is similar to that of the groundwater. These data are not consistent with equilibrium isotopic exchange between the aqueous sulfate and the groundwater and suggest that the rate of equilibration is very slow because the groundwater and sulfate in the nonweathered zone have been in contact for up to 37,000 years. Isotopic balance calculations imply that most of the oxygen in the sulfate produced by the oxidation of reduced sulfur in the weathered zone is incorporated from the associated water molecules.

OSTI ID:
6898293
Journal Information:
Water Resources Research; (USA), Journal Name: Water Resources Research; (USA) Vol. 25:3; ISSN 0043-1397; ISSN WRERA
Country of Publication:
United States
Language:
English