Groundwater, Isotope, Lake-Effect, Precipitation, Oxygen, Hydrogen, Protium, Deuterium, Water, Fractionation, Partitioning, Lake Michigan, VSMOW, GMWL




Tara Kneeshaw


Three different stable isotopes of water occur in nature, with the majority of water on Earth containing the oxygen isotope 16O. These isotopes have slightly differing physical and chemical properties. H2O with heavier oxygen isotopes should theoretically precipitate earlier than lighter isotope H2O, meaning this natural process should allow for the observation of the magnitude of effects of lake-effect precipitation on the basis of water isotope differences. Furthermore, it may allow for better understanding of the significance lake-effect precipitation plays in recharging shallow aquifers. In this study, patterns of lake-effect precipitation from Lake Michigan were observed in a collection of water samples from shallow-depth (<80 ft) aquifers across West Michigan. Difference in isotope concentrations of collected groundwater samples did not appear to vary significantly based on factors such as longitude or well depth. It was concluded that partitioning of water isotopes observed in Lake Michigan sourced precipitation does not have an appreciable effect on groundwater geochemical composition within the region of observation of this study.

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