STABLE ISOTOPES δ18O AND δD IN THE OLENTANGY RIVER
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Date
2018-05
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The Ohio State University
Abstract
Natural bodies of water have varying isotopic signatures of δ18O and δD depending on
their geographic location and the surrounding climate. These stable isotopes can be used to
fingerprint water samples, allowing scientists to describe characteristics of incoming
precipitation and terrestrial bodies of water. The Global Meteoric Water Line (GMWL) describes
the ratio of δD to δ18O of precipitation from around the world. The equation of this line is δD= 8
* δ18O + 10. Every location has a Local Meteoric Water Line (LMWL) that deviates from
GMWL, describing its precipitation. This project investigated the isotopic signature of the
Olentangy River in Columbus, Ohio. Samples were collected from December, 2017 to February,
2018. Samples were collected with no headspace and transferred into 2 mL vials for isotopic
analysis. Isotopes δ18O and δD were analyzed using the Picarro Wavelength Scanned-Cavity
Ring Down Spectroscopy Analyzer for Isotopic Water-Model L1102-i. River samples were
standardized by internal lab δ18O and δD standards from Colorado, Nevada, Ohio, and Florida.
Results were compared to the central Ohio LMWL, which was developed by the Anne Carey
research group. The trendline describing the Olentangy river samples was y= 6.77x – 0.655 (R2=
0.99), which had a similar slope but a lower intercept than the central Ohio LMWL. Samples
strongly reflect the local precipitation, showing minimal amounts of evaporation during the
winter months.
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Keywords
Olentangy River, Stable Isotopes, Isotope Hydrology, Meteoric Water