CALCIUM ISOTOPIC ANALYSIS OF WATER SAMPLES ON SAN SALVADOR ISLAND, THE BAHAMAS
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Date
2024-05
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The Ohio State University
Abstract
Water chemistry of lakes and ponds on San Salvador Island in The Bahamas are influenced by the geological make-up of the island as well as seawater intrusions and the presence of conduits connecting the surface waters to seawater. Evaporation rates are also important for lakes and ponds in The Bahamas. The chemistry of water samples collected on the island were compared to their calcium isotopic composition (δ44/40Ca) to determine how similar the water bodies are to seawater. Seven different water samples were collected and analyzed for δ44/40Ca and elemental concentrations of calcium (Ca), magnesium (Mg), and strontium (Sr). The δ44/40Ca values and elemental concentrations (Ca, Mg, and Sr) were used to determine factors that may affect water chemistry such as evaporation, sea spray, presence of a conduit (connection to the ocean), and carbonate rock dissolution by freshwater infiltration. From my results, all samples excluding Inkwell Blue Hole, Salt Pond and the shallow groundwater sample from the Gerace Research Centre (GRC) well, look similar to seawater based on δ44/40Ca compositions. Inkwell Blue Hole and the GRC well both had δ44/40Ca values that were lower than seawater and resembled carbonate rocks. The hypersaline Salt Pond had high concentration of Ca but a lower δ44/40Ca than seawater suggesting that the water chemistry may be influenced by other processes such as elevated evaporation rates and carbonate rock dissolution or mineral precipitation.