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Inference from Polar Ice Cores Thomas S South Dakota State University Open PRAIRIE: Open Public Research Access Institutional Repository and Information Exchange Theses and Dissertations 2017 Investigating the Atmospheric Production of Perchlorate: Inference from Polar Ice Cores Thomas S. Cox South Dakota State University Follow this and additional works at: http://openprairie.sdstate.edu/etd Part of the Analytical Chemistry Commons, Atmospheric Sciences Commons, and the Environmental Sciences Commons Recommended Citation Cox, Thomas S., "Investigating the Atmospheric Production of Perchlorate: Inference from Polar Ice Cores" (2017). Theses and Dissertations. 1664. http://openprairie.sdstate.edu/etd/1664 This Dissertation - Open Access is brought to you for free and open access by Open PRAIRIE: Open Public Research Access Institutional Repository and Information Exchange. It has been accepted for inclusion in Theses and Dissertations by an authorized administrator of Open PRAIRIE: Open Public Research Access Institutional Repository and Information Exchange. For more information, please contact [email protected]. INVESTIGATING THE ATMOSPHERIC PRODUCTION OF PERCHLORATE: INFERENCE FROM POLAR ICE CORES BY THOMAS S. COX A dissertation submitted in partial fulfillment of tHe requirements for tHe Doctor of Philosophy Major in CHemistry South Dakota State University 2017 iii ACKNOWLEDGEMENTS THere Have been many people wHo Have assisted in tHis project as well as assisted me on tHis academic endeavor, and I would like to take a moment to tHank these individuals. First and foremost, I would like to tHank my advisor, my mentor, my friend, Dr. Jihong Cole-Dai for His support, guidance, and Humor. At times, Dr. Cole-Dai has cHallenged me to my core, wHile also providing insight and clarity when needed. He Has pusHed me to seek a greater understanding of tHe ideas and concepts I Have studied, as well as provided encouragement to continually work on and improve tHe communication of sucH ideas. WitHout His guidance and insigHt, tHe completion of tHis project would most definitely not Have been possible. I would also like to tHank tHe members of my advisory committee (botH past and present): Dr. Douglas Raynie, Dr. Matt Miller, Dr. Brian Logue, Dr. Melissa Hauschild-Mork, and Dr. Niall Hanan. I would like to thank the Campus Core Mass spectrometry Facility for access to and maintenance of tHe QTRAP 5500 tandem mass spectrometer. I would like to tHank tHe members of tHe ICECL lab: Lei Geng for discussing SDSU grad school long before I applied. Kari Peterson for providing insightful discussion, being a good running partner, and Having a good taste in music. Dave Ferris for providing tHe SPC14 samples, continually providing encouragement and support, and for exemplifying friendsHip. JosHua Kennedy for providing insightful discussions, assistance with statistical analyses and interpretation, as well as an iv overall fun colleague and friend. Carleigh Larrick for providing distractions when I needed tHem most. I would also like to thank Mark Twickler and Richard Nunn for providing and shipping the WDC05B and SP04C1 ice cores, as well as Brad Markle for providing tHe WDC13 samples and NatHan CHellman for providing tHe GEOSummit snow samples. THese samples were tHe core of this project, and this work could not have been completed witHout tHe assistance of tHese individuals. I would also like to tHank tHe Brookings and CFB community for tHe friendship and support that they have provided over the years, in one way or another. Finally, I would like to tHank my family. THey Have provided love and support throughout this five-year pursuit. WitHout tHe numerous care packages, travel support for holiday visits, long-term dog sitting, and otHer metHods of encouragement, it would be unlikely that I would be finishing this journey with a smile on my face. And Patton – I would not have begun this challenging pursuit had it not been for you. v TABLE OF CONTENTS ABBREVIATIONS ....................................................................................................................................... ix LIST OF TABLES ..................................................................................................................................... xiii 1. Introduction ............................................................................................................................................ 1 1.1 PercHlorate in tHe environment .............................................................................................. 1 1.1.1 Health concerns ..................................................................................................................... 1 1.2 Sources of environmental percHlorate ................................................................................ 2 1.2.1 AntHropogenic percHlorate .............................................................................................. 2 1.2.2 Natural perchlorate ............................................................................................................. 2 1.3 Isotopic composition of percHlorate ..................................................................................... 3 1.3.1 Oxygen isotopes .................................................................................................................... 4 1.3.3 Chlorine isotopes .................................................................................................................. 6 1.4 Records of environmental percHlorate ................................................................................ 8 1.5 Ice core records of perchlorate ............................................................................................ 10 1.6 Objectives ...................................................................................................................................... 11 2. Ice cores and cHemical measurement ....................................................................................... 13 2.1 Ice Core collection ...................................................................................................................... 13 2.2 Major ion analysis ...................................................................................................................... 15 2.3 Analytical tecHniques for measuring percHlorate ........................................................ 16 2.3.1 Perchlorate analysis by IC-ESI-MS/MS .................................................................... 18 2.3.2 Optimized mass spectrometer parameters ............................................................ 19 2.3.3 Selectivity .............................................................................................................................. 21 2.3.4 Interlaboratory comparison ......................................................................................... 22 vi 2.4 Sample preparation ................................................................................................................... 24 2.5 Operational blanks ..................................................................................................................... 25 2.6 Dating Methods ........................................................................................................................... 26 2.6.1 Annual layer counting ........................................................................................................... 26 2.7.2 WAIS Divide snow ............................................................................................................. 34 2.7.3 Monthly dating .................................................................................................................... 38 2.8 Data analyses ................................................................................................................................ 39 2.8.1 Dating smootHing ............................................................................................................... 39 2.8.2 Power spectral analysis .................................................................................................. 39 3. Depositional and post-depositional processes ..................................................................... 43 3.1 Deposition ..................................................................................................................................... 44 3.1.1 Perchlorate deposition .................................................................................................... 45 3.2 Post-depositional processes .................................................................................................. 49 3.2.1 Perchlorate: a decreasing trend with deptH ......................................................... 50 3.2.2 Post-depositional loss of perchlorate in South Pole snow ............................... 51 3.2.3 PercHlorate loss mecHanism ......................................................................................... 54 3.2.4 Quantifying post-depositional loss ............................................................................ 56 3.3 Preservation of perchlorate in snow ................................................................................. 58 3.4 Characteristics of sites with post-depositional changes ........................................... 61 3.4.1 Accumulation Rate and Temperature ....................................................................... 62 3.5 Conclusion ....................................................................................................................................
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