Spatial and Temporal Geochemical Characterization of Aeolian Material from the McMurdo Dry Valleys, Antarctica A Thesis Presented in Partial Fulfillment of the Requirements for the Degree Master of Science in the Graduate School of The Ohio State University By Melisa A. Diaz Graduate Program in Earth Sciences The Ohio State University 2017 Master’s Examination Committee: Dr. W. Berry Lyons, Advisor Dr. Michael Barton Dr. Michael Wilkins Copyright by Melisa A. Diaz 2017 Abstract Aeolian processes play an important role in the transport of both geological and biological materials globally, on the biogeochemistry of ecosystems, and in landscape evolution. As the largest ice free area on the Antarctic continent (approximately 4800 km2), the McMurdo Dry Valleys (MDV) are potentially a major source of aeolian material for Antarctica, but information on the spatial and temporal variability of this material is needed to understand its soluble and bulk geochemistry, deposition and source, and hence influence on ecosystem dynamics. 53 samples of aeolian material from Alatna Valley, Victoria Valley, Miers Valley, and Taylor Valley (Taylor Glacier, East Lake Bonney, F6 (Lake Fryxell), and Explorer’s Cove) were collected at five heights (5, 10, 20, 50, 100 cm) above the surface seasonally for 2013 through 2015. The sediment was analyzed for soluble solids, total and organic carbon, minerology, and bulk - - chemistry. Of the soluble component, the major anions varied between Cl and HCO3 , and the major cation was Na+ for all sites. Soluble N:P ratios in the aeolian material reflect nutrient limitations seen in MDV soils, where younger, coastal soils are N-limited, while older, up valley soils are P-limited. Material from East Lake Bonney was P-limited in the winter samples, but N-limited in the full year samples, suggesting different sources of material based on season. Analysis of soluble salts in aeolian material in Taylor Valley compared to published soil literature demonstrates a primarily down valley transport of materials from Taylor Glacier towards the coast. The bulk chemistry suggests that the ii aeolian material is highly unweathered (CIA values less than 60 %), but scanning electron microscope images show alteration for some individual sediment grains. The mineralogy was reflective of local rocks, specifically the McMurdo Volcanics, Ferrar Dolerite, Beacon Sandstone and granite, but variations in major oxide percentages and rare earth element signatures could not be explained by mixing lines between these four rock types. This potentially suggests that there may be an additional, and possibly distant, source of aeolian material to the MDV that is not accounted for. This work provides the first fully elevated spatial and temporal analysis of the geochemistry of aeolian material from the Dry Valleys, and contributes to a better understanding of sediment provenance and how aeolian deposition may affect surface biological communities. iii Acknowledgments I would first like to thank Dr. Berry Lyons for his continuous efforts in helping me develop as a researcher. I have learned a copious amounts of information from him and look forward to learning even more in coming years. Thank you to Kathy Welch and Chris Gardner for guidance in both life and science, and Sue Welch and Julie Sheets for thoughtful discussions, particularly with mineralogy. To Sydney Olund, thank you for being a great office mate and an even greater friend. I will miss our conversations and weekly debates. To Cyrus, thank you for all your love and support. I will always appreciate your company during long work days. Lastly, this work could not be possible without the help of the McMurdo LTER research team members Byron Adams, Alia Khan, and Andy Thompson, logistical support from ASC, helicopter support from PHI, and funding support from NSF ANT 1115245. iv Vita October 1992 ..................................................Born – Queens, NY May 2014 ......................................................B.S. Earth and Environmental Sciences, University of Rochester January 2016 to present ................................Graduate Teaching/Research Associate, School of Earth Sciences, The Ohio State University Field of Study Major Field: Earth Sciences v Table of Contents Abstract ............................................................................................................................... ii Acknowledgments.............................................................................................................. iv Vita ...................................................................................................................................... v List of Figures .................................................................................................................. viii List of Tables ...................................................................................................................... x 1. Introduction ..................................................................................................................... 1 1.1 Wind Patterns .................................................................................................... 2 1.2 Aeolian Transport and Deposition .................................................................... 3 2. Study Objectives and Questions ..................................................................................... 6 3. Study Sites ...................................................................................................................... 7 3.1 Miers Valley...................................................................................................... 8 3.2 Taylor Valley .................................................................................................... 9 3.3 Victoria Valley ................................................................................................ 10 3.4 Alatna Valley .................................................................................................. 11 4. Methods......................................................................................................................... 13 4.1 Sample Collection ........................................................................................... 13 4.2 Sample Processing and “Clean” Technique Philosophy ................................. 15 4.3 Water Soluble “Leaches” ................................................................................ 15 4.4 Nutrients .......................................................................................................... 16 4.5 Cations and Anions ......................................................................................... 17 4.6 Total Nitrogen and Total and Organic Carbon ............................................... 18 4.7 Mineral Geochemistry .................................................................................... 19 4.8 X-ray Diffraction (XRD) ................................................................................ 19 4.9 Scanning Electron Microscopy (SEM) ........................................................... 20 5. Results ........................................................................................................................... 22 5.1 Wind Distribution ........................................................................................... 22 5.2 Soluble Solids ................................................................................................. 22 vi 5.3 Total and Organic Carbon ............................................................................... 24 5.4 Sediment Geochemistry .................................................................................. 25 5.5 Mineralogy ...................................................................................................... 26 5.6 Grain Size, Composition and Encrustations from SEM ................................. 27 6. Discussion ..................................................................................................................... 31 6.1.1 Aeolian Composition- Water Soluble Component ...................................... 32 6.1.2 Spatial and Seasonal Variability .................................................................. 34 6.1.3 Down Valley Transport................................................................................ 38 6.2.1 Aeolian Composition- Solid Component ..................................................... 42 6.2.2 Geographic Provenance ............................................................................... 46 6.3.1 Analysis of Variance (ANOVA) .................................................................. 50 7. Conclusions ................................................................................................................... 52 8. Future Work .................................................................................................................. 54 9. References ..................................................................................................................... 56 10. Figures and Tables ...................................................................................................... 65 Appendix A: Detection limits and Precision and Accuracy ........................................... 134 Appendix B: Total Mass of Aeolian Sample .................................................................. 139 Appendix C: Analysis of Variance (ANOVA) Results .................................................