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Florida State University Libraries 2016 The Use of Stable Isotopes Deuterium and Oxygen-18 as Natural Hydrologic Tracers in a Florida Springshed Erica Rau Follow this and additional works at the FSU Digital Library. For more information, please contact [email protected] FLORIDA STATE UNIVERSITY COLLEGE OF ARTS AND SCIENCES THE USE OF STABLE ISOTOPES DEUTERIUM AND OXYGEN-18 AS NATURAL HYDROLOGIC TRACERS IN A FLORIDA SPRINGSHED By ERICA L. RAU A Thesis submitted to the Department of Earth, Ocean and Atmospheric Science in partial fulfillment of the requirements for the degree of Master of Science 2016 Erica L. Rau defended this thesis on March 21, 2016. The members of the supervisory committee were: Yang Wang Professor Co-Directing Thesis Jeffrey P. Chanton Professor Co-Directing Thesis William M. Landing Committee Member The Graduate School has verified and approved the above-named committee members, and certifies that the thesis has been approved in accordance with university requirements. ii ACKNOWLEDGMENTS I would like to acknowledge my great appreciation for the guidance and instruction from my thesis committee, Dr. Yang Wang, Dr. Jeffery Chanton, and Dr. William Landing, and would like to thank all my professors at Florida State University for their dedication and inspiration. Special thanks is in order to Glynnis Burgna at the Florida Agricultural and Mechanical University Wetlands Ecology Laboratory for accommodating and directing my use of the Los Gatos laser isotope analyzer and to Dr. Wang for instruction in and use of the mass spectrometer at the National High Magnetic Field Laboratory at FSU. Brian Katz, Hal Davis, Christy Crandall, Trey Grubbs, Rich Marella, and Dale Griffin are deeply appreciated for all the conversations about hydrology and for all their research that was carried out at the United States Geological Survey Tallahassee office. I would also like to thank Ed Chelette from the Florida Geological Survey for demonstrating their water sampling procedures at Wakulla Spring and for the wealth of information made available to the public through online access to their publications. Thanks to Gary Maddox at the Florida Department of Environmental Protection for permission to use the sampling line installed at the spring. I would like to express my gratitude to Wakulla Springs State Park biologist Scott Savery and park staff for their ongoing interest and cooperation with research done on the springs, with extra special thanks for all the break-of-day boat rides they gave me to the spring vent to collect water samples. I would also like to express my gratefulness for Robert Knight’s Springs Ecology course at the University of Florida and my great esteem for Jim Stevenson’s knowledge of the Wakulla watershed and ongoing contributions to public awareness of Florida’s environmental issues. iii TABLE OF CONTENTS List of Tables ...................................................................................................................................v List of Figures ................................................................................................................................ vi Abstract ........................................................................................................................................ viii 1. INTRODUCTION ......................................................................................................................1 Purpose and Scope ......................................................................................................................1 Study Area ...................................................................................................................................2 Previous Studies in the Wakulla Springshed ............................................................................27 Isotope Chemistry in Hydrology ...............................................................................................33 2. METHODS ...............................................................................................................................50 Field Methods ...........................................................................................................................50 Laboratory Methods ..................................................................................................................62 3. RESULTS .................................................................................................................................70 Summary ...................................................................................................................................70 North and Central Florida Springs during Base Flow and Non-base Flow Conditions ............70 Wakulla Spring Samples ...........................................................................................................85 4. DISCUSSION AND CONCLUSIONS ....................................................................................98 Sampling Method Notes ............................................................................................................98 Variability of Isotope Composition of Florida Springs ............................................................99 Use of Deuterium and Oxygen-18 as Hydrologic Tracers ......................................................103 Hydrograph Separation: The Integration of Streamflow and Isotope Data ............................107 Conclusions .........................................................................................................................…113 APPENDICES .............................................................................................................................116 A. WATER QUALITY DATA ....................................................................................................116 B. BACKGROUND INFORMATION .......................................................................................119 C. ISOTOPE ANALYSES ..........................................................................................................121 References ....................................................................................................................................124 Biographical Sketch .....................................................................................................................145 iv LIST OF TABLES Table 1: Classification of Springs ....................................................................................................3 Table 2: Results of Isotope Analyses of Florida Spring Samples ..................................................73 Table 3: Results of Isotope Analyses of Wakulla Spring Samples ................................................96 v LIST OF FIGURES Figure 1: Map of Spring Locations Sampled in North and Central Florida ....................................4 Figure 2: Map of the Wakulla Springshed .......................................................................................6 Figure 3: Sinkhole Map .................................................................................................................14 Figure 4: Sellard’s Sketch of Sinking Streams ..............................................................................15 Figure 5: Ames Sink Taking in Water ...........................................................................................16 Figure 6: Stage-discharge Relationship for Wakulla River near Crawfordville, FL(2005–2016).20 Figure 7: Stage-discharge Relationship for Lost Creek at Arran, FL(1998–2016) .......................20 Figure 8: Land Use in the Wakulla/St. Marks Watershed .............................................................24 Figure 9: Population Growth 1900–2010 ......................................................................................24 Figure 10: Measurements of Streamflow for Wakulla Springs and River, 1907–2016 .................32 Figure 11: Measurements of Streamflow for Ichetucknee River, 1898–2016 ...............................33 Figure 12: Example of Water-velocity Data for Wakulla River ....................................................54 Figure 13: Preparation of Water Samples for Laser-based Isotope Analysis ................................65 Figure 14: Wakulla Spring Samples to be Analyzed by Isotope Ratio Mass Spectrometry ..........68 Figure 15: Linear Regression of Isotope Values for Springs during Drought Conditions ............71 Figure 16: Isotope Composition of Springs during Base Flow Conditions ...................................74 Figure 17: Isotope Composition of Springs during Non-base Flow Conditions ...........................74 Figure 18: Palmer Drought Severity Index for Wakulla and Leon Counties ................................83 Figure 19: Comparison of Springs’ Isotope Values from Dry to Wet Conditions ........................84 Figure 20: Hydrograph for the 2012 Water Year, Wakulla River near Crawfordville, FL ...........86 Figure 21: Hydrograph for the 2013 Water Year, Wakulla River near Crawfordville, FL ...........86 Figure 22: Specific Conductance at Wakulla Spring for the 2013 Atlantic Hurricane Season .....87 vi Figure 23: Precipitation Record for the 2012 Hurricane Season (NWS) .......................................88 Figure 24: Time Series for Deuterium in Wakulla Spring Samples 2012 .....................................89 Figure 25: Time Series for Oxygen-18 in Wakulla Spring Samples 2012 ....................................90 Figure 26: Precipitation