Minor Alkaline Earth Element and Alkali Metal Behavior in Closed-Basin Lakes Dissertation Presented in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy in the Graduate School of The Ohio State University By Rebecca A. Witherow Graduate Program in Geological Sciences The Ohio State University 2009 Dissertation Committee: W. Berry Lyons, Advisor Anne Carey Ozeas Costa David Porinchu William Green This page intentionally left blank. ii Abstract Hydrologically closed basins in arid environments often pose ideal conditions for the development of inland saltwater lakes. In these regions, where the hydrology is balanced by dilute inflow waters and evaporation, these closed-basin lakes may progress through various degrees of evapoconcentration. This process may result in the precipitation of simple salts and the alteration of the relative chemical composition of a lake. Such “geochemical evolution” processes have been studied in detail particularly for the so-called major ions (Na, Ca, K, Mg, Cl, SO4, HCO3+CO3) and Si, but little work has been done on ions of moderate concentration. Due to the evaporative nature of these systems, the alkali metals, Li and Rb, and alkaline earth elements, Sr and Ba, may become highly concentrated and play a significant role in determining the geochemistry of a saline lake. Here, I present the first comprehensive study of the transport and fate of the minor alkali elements, Li, Rb, Sr, and Ba, in three distinct geographic settings illustrating three types of saline lakes as determined by their major anion abundance. Using lithium isotope analysis and mass balance calculations, I show that the minor elements in the McMurdo Dry Valleys are transported to “chloride-type” lakes by a combination of precipitation, chemical weathering and salt dissolution. Sr and Ba show evidence of removal in the lakes, but Li and Rb appear to be conservative to extremely high concentrations. This work discusses the potential removal mechanisms of these ions, particularly the formation of major and minor sulfate and carbonate minerals in the lakes. A major finding of this study is that brine type determines the removal mechanism of Sr and Ba, particularly if they are removed as sulfate or ii carbonate minerals. This study provides a platform for future exploration of the role of these and other minor elements in inland brines and playas. iii Dedicated to my parents. iv Acknowledgments I wish to thank my adviser, W. Berry Lyons for his guidance, insight, and patience. Berry has been an amazing mentor and has taught me much about science and what it means to be a scientist. He has been supportive of my ideas, and he has given me direction when I’ve needed it. I am forever grateful for the opportunities he has given me. He has helped me achieve my goals of seeing the world, including Antarctica and the Arctic, and obtaining my Ph.D.. It has been a true honor working with him through the years. My thanks go to my committee members, Anne Carey, Ozeas Costa, Dave Porinchu and William Green for their scientific and stylistic comments and suggestions. Their unique perspectives have greatly enhanced this dissertation, and I am indebted to their commitment. I also wish to thank Kathleen Welch, Joel Barker, Sarah Fortner, and Christopher Gardner for their friendship, field assistance, scientific knowledge, and editorial comments. Their advice support has made me a better scientist, and I will always have fond memories of our times together. It has been a pleasure working with the past and present members of the McMurdo Dry Valleys Long Term Ecological Research project. The collaboration within the group is inspirational, and I admire their commitment to understanding the McMurdo Dry Valleys ecosystem. I am especially grateful for the collection of lake samples by the Montana State Limno Team and for the University of Colorado Stream Team for stream sample collection. I am indebted to the support staff in the McMurdo Dry Valleys especially Rae Spain and Sandra Liu. v Their hospitality at Lake Hoare camp is unparalleled, and they have made Antarctica feel like home. This work could not have been completed without the assistance of several people. John Olesik and Anthony Lutton from TERL at OSU were extremely helpful assisting in ICPMS analysis. Gideon Henderson and Andrew Mason at Oxford University were essential in lithium isotope analysis and interpretation. I am grateful for the generosity of William Last for donating lake samples to this project. This journey through graduate school has been long and difficult, and I am sincerely thankful for the moral support of my family and friends. Thank you Shawn, Mom, and Dad for listening to me, letting me cry, and telling me I’m smart. Thanks Casey and Laura for listening to my stories. To all of my friends going through the same thing, thank you for making me feel like I’m not alone. This work was supported by NSF-ANT grant #0423595, a GSA Graduate Student Research Grant, and an OSU Office of International Affairs Travel Grant. vi Vita 2001 .......................................................................................................... B.A. Geology, Miami University 2005 ........................................................................ M.S. Geological Sciences, The Ohio State University 2002-present ....................................................................... Graduate Teaching and Research Associate, The Ohio State University Publications 1. Harmon, R.S., Lyons, W.B., Long, D.T., Odgen, F.L., Mitasova, H, Gardner, C.B., Welch, K.A., Witherow, R.A. (2009) Geochemistry of four tropical montane watersheds, central Panama. 24(4), Applied Geochemistry. 2. Witherow, R.A. and Lyons, W.B. (2008) Mercury deposition in a polar desert ecosystem. Environmental Science and Technology. 42(13), 4710-4716. 3. Witherow, R.A., Lyons, W.B. (2008) The role of minor alkali elements in the evolution of closed-basin lakes. GSA Abstracts with Programs. 40(6). 4. Witherow, R.A., Henderson, G., Lyons, W.B. (2008) Lithium isotopes in a polar desert, McMurdo Dry Valleys, Antarctica. Goldschmidt Conference Abstracts. A1029. 5. Fortner, S.K., Lyons, W.B., Witherow, R.A., Welch, K.A., Olesik, J.W. (2007) Trace metal dynamics and transport in a polar glacier-dominated watershed: Taylor Valley, Antarctica. Goldschmidt Conference Abstracts 2007. A289. 6. Witherow, R.A., Lyons, W.B., Welch K.A. (2007) Geochemical controls on major and minor alkaline elements in closed-basin lakes, Taylor Valley, Antarctica. GSA Abstracts with Programs. 39(6). 7. Lyons, W.B., Harmon, R.S., Gardner, C., Welch, K.A., Witherow, R.A., Long, D.T. (2006) The geochemistry of headwater streams, central Panama: Influence of watershed rock type. GSA Abstracts with Programs. 38(7), 96. vii 8. Witherow, R.A., Lyons, W.B., Bertler, N.A.N., Welch, K.A., Mayewski, P.A., Sneed, S.B., Nylen, T., Handley, M.J., Fountain, A. (2006) The aeolian flux of calcium, chloride and nitrate to the McMurdo Dry Valleys landscape: Evidence from snow pit analysis. Antarctic Science. 18(4), 497-505. Field of Study Major Field: Geological Sciences viii Table of Contents Abstract ......................................................................................................................................................... ii Acknowledgments ...................................................................................................................................... v Vita ....................................................................................................................................................... vii List of Figures.............................................................................................................................................. xi List of Tables .............................................................................................................................................. xv Introduction .............................................................................................................................................. xvi Chapter 1 Geochemical Dynamics of Minor Elements in Closed-Basin Lakes in Antarctica ......... 1 1.1 Abstract ............................................................................................................................. 1 1.2 Introduction ...................................................................................................................... 1 1.3 Site Description ................................................................................................................ 4 1.4 Methods ............................................................................................................................ 6 1.5 Results ............................................................................................................................. 10 1.5.1 Major ion concentrations ................................................................................... 10 1.5.2 Concentrations of minor elements in streams .................................................... 12 1.5.3 Minor element concentrations in lakes ............................................................... 15 1.5.4 Minor elements in lake sediments ...................................................................... 21 1.6 Discussion ....................................................................................................................... 32 1.6.1 Minor alkali metals and alkaline earths in MCM