Environmental isotopes (18O, 2H, and 87Sr/86Sr) as a tool in groundwater investigations in the Keta Basin, Ghana |
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| Authors: | Niels O Jørgensen Bruce K Banoeng-Yakubo |
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| Institution: | Geological Institute, University of Copenhagen, ?ster Voldgade 10, DK-1350 Copenhagen, Denmark,
Department of Geology, University of Ghana, P.O. Box 58, Legon, Ghana,
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| Abstract: | Analyses of environmental isotopes (18O, 2H, and 87Sr/86Sr) are applied to groundwater studies with emphasis on saline groundwater in aquifers in the Keta Basin, Ghana. The 87Sr/86Sr ratios of groundwater and surface water of the Keta Basin primarily reflect the geology and the mineralogical composition
of the formations in the catchments and recharge areas. The isotopic compositions of 18O and 2H of deep groundwater have small variations and plot close to the global meteoric water line. Shallow groundwater and surface
water have considerably larger variations in isotopic compositions, which reflect evaporation and preservation of seasonal
fluctuations. A significant excess of chloride in shallow groundwater in comparison to the calculated evaporation loss is
the result of a combination of evaporation and marine sources. Groundwaters from deep wells and dug wells in near-coastal
aquifers are characterized by relatively high chloride contents, and the significance of marine influence is evidenced by
well-defined mixing lines for strontium isotopes, and hydrogen and oxygen stable isotopes, with isotopic compositions of seawater
as one end member. The results derived from environmental isotopes in this study demonstrate that a multi-isotope approach
is a useful tool to identify the origin and sources of saline groundwater.
Electronic Publication |
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| Keywords: | stable isotopes radioactive isotopes salinization salt-water/fresh-water relations Ghana |
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