Date

Spring 5-3-2019

Document Type

Honors Project

First Advisor

Grothe, Pamela

Second Advisor

Whipkey, Charles

Third Advisor

Szulczewski, Melanie

Department Chair or Program Director

Hayob-Matzke, Jodie

Degree Name

Bachelor of Science

Major or Concentration

Environmental Geology

Department or Program

Earth and Environmental Sciences

Abstract

Stable isotopes of oxygen and hydrogen, δ18O and δD, are tracers of climatic changes within the hydrologic cycle, and thus are a potential link in the relationship between climate-influenced changes to the hydrologic cycle and modern and paleoenvironments. Studies have shown that the isotopic content of surface water and groundwater parallel meteoric water (e.g. Dutton et al., 2005), a relationship expected to be reflected in marine paleoclimate archives, such as those from the Chesapeake Bay, which are sensitive to freshwater input from rivers (e.g. LeGrande and Schmidt, 2009). In this study, we establish a baseline of isotopic composition of precipitation, stream, and groundwater in Fredericksburg, Virginia, to study the seasonality of δ18O and δD within the water. We have found precipitation in winter months to be more depleted in heavy isotopes than in warmer months, indicating the influence of temperature on isotopic abundance. Periods of high rainfall frequency result in greater variability of the δ18O and δD of stream water; however, periods of prolonged dryness resulted in deviations of this trend due to high rates of evaporation and the inflow groundwater into the stream. This work will provide the foundation of using δ18O and δD of meteoric water to study changing precipitation patterns as climate changes in the local Fredericksburg, VA region, as well as understanding the controls of the δ18O and δD of surface water for more robust interpretations from proxy records in regional paleoclimate studies.

Language

English

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