Stable isotope and chemical compositions of surface and subsurface waters in Saskatchewan
Date
1987
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
ORCID
Type
Degree Level
Masters
Abstract
The stable isotope and chemical compositions of water samples
from several Upper Cretaceous and Quaternary aquifers in Saskatchewan
were measured to determine the source of recharge within the
individual aquifers and the various factors that have affected the
waters in these aquifers since their formation. δD and δ¹⁸O values of
waters from near-surface aquifers in Saskatchewan plot near the global
Meteoric Water Line indicating that the waters present are meteoric in
origin and generally have not been involved in appreciable evaporation
or water-rock exchange reactions, as both processes enrich the samples
differentially in D and ¹⁸O. Isotopic compositions in conjunction
with water level records for the aquifers indicate that the
predominant recharge occurs in the spring, coinciding with melting of
winter snow accumulations in the province. Minor recharge is also
expected from high intensity summer rain storms, however, the δD and δ¹⁸O values suggest that this input is minimal. Variations in the
isotopic compositions of water samples from individual aquifers
studied suggest that little or no interaction occurs between aquifers,
even those located within the same stratigraphic zones.
The dissolved constituents, which range from 200 to 3700 mg/1,
are derived from the interaction of the recharging waters with
sediments during infiltration to, and residence in, the aquifers, so
that the chemical compositions of subsurface waters are controlled by
the local geology. Due to the low temperatures and pressures near the
earth's surface and the relatively rapid rate of infiltration, only the most soluble ions available within the sediments will dissolve.
Aquifers within Quaternary and Upper Cretaceous sediments in
Saskatchewan are saturated or nearly saturated with respect to several
mineral phases including calcite, dolomite, anhydrite and gypsum, all
of which are present in the local sediments.
The isotopic compositions of surface waters in Saskatchewan vary
substantially. Variations in the δD and δ¹⁸O values result from
differences in the source of recharge (i.e. summer versus winter
precipitation), surface temperature, size of the water body, and
degree of evaporation that occurs in each body. More pronounced
enrichments of D and ¹⁸O are recorded in the smaller lakes and creeks
relative to the larger river systems as a result of surface evaportion.
Because the amount of evaporation that occurs is
dependent on temperature and degree of saturation of the local air
masses, enrichments in D and ¹⁸O can be considerable during the summer
months in Saskatchewan when temperatures are high and relative
humidities low.
Description
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Citation
Degree
Master of Science (M.Sc.)
Department
Geological Sciences
Program
Geological Sciences