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Mineralogy of Dust Emissions from the Bodele Depression

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Mineralogy of Dust Emissions from the Bodele Depression MINERALOGY OF DUST EMISSIONS FROM THE BODELE DEPRESSION By ROSEMARY ASSUNTA MILLHAM Bachelor of Science State University of New York at New Paltz New Paltz, NY 1983 Master of Science in Education State University of New York at New Paltz New Paltz, NY 1987 Submitted to the Faculty of the Graduate College of the Oklahoma State University in partial fulfillment of the requirements for the Degree of DOCTOR OF PHILOSOPHY July, 2007 MINERALOGY OF DUST EMISSIONS FROM THE BODELE DEPRESSION Dissertation Approved: Steven Marks ________________________________________________ Dissertation Adviser Caroline Beller ________________________________________________ Steve Stadler ________________________________________________ Jack Vitek ________________________________________________ A. Gordon Emslie ________________________________________________ Dean of Graduate College ii ACKNOWLEDGEMENTS This dissertation is dedicated to the memory of Yoram Kaufman, a dedicated scientist, and good friend. Thank you for believing in me. It is with sincere thoughts and attitudes that I acknowledge the roles that Yoram Kaufman, Ilan Koren, and Vanderlei Martins have played in the development of my dissertation topic that was based on a need in the scientific community as essential to understanding climate, climate change, and climate modeling as the weather is to understanding climate. Through their dogged belief in my abilities, patience in the explanation of the difficult to explain, and the trust they placed on me in my own abilities as a geologist, Yoram, Ilan, and Vanderlei pushed the envelope of my resolve and dedication to complete the task. To Steve Marks and Jack Vitek, to whom I owe the deepest gratitude for their unfailing support, advice, and direction, I say thank you for your valued trust in my work ethics, dedication, and abilities. To my family, especially to my adult children, Jennifer and Matthew, I am amazed and truly blessed to know how much faith you have in me to accomplish something I thought was unreachable. To my husband, Bobby Boy, thanks for all of the meals and doggie walks that allowed me to work uninterrupted for days at a time when I needed the time to follow through on an idea, concept, or theory. You are truly one-of-a- kind. iii TABLE OF CONTENTS Chapter Page I. INTRODUCTION .....................................................................................1 Statement of the Problem .....................................................................4 Purpose of the Study.............................................................................5 Significance of the Study......................................................................5 Research Questions ..............................................................................6 Definition of Terms..............................................................................7 Scope of Study ...................................................................................28 Limitations.........................................................................................28 Assumptions.......................................................................................29 II. REVIEW OF LITERATURE...................................................................31 Introduction........................................................................................31 Aerosols in General............................................................................44 Primary and Secondary Sources of Aerosols.......................................48 Aerosol Light Scattering Efficiency....................................................55 Aerosols and Cloud Formation ...........................................................66 Atmospheric Mineral Dust .................................................................72 Geological and Geomorphological Considerations .............................75 The Bodele ........................................................................................84 Summary............................................................................................88 III. METHODOLOGY...................................................................................90 Procedures and Instrumentation..........................................................90 Data Collection ..................................................................................92 Data Analysis.....................................................................................94 IV. FINDINGS AND ANALYSIS OF DATA................................................96 Analysis of SEM Bulk Data................................................................98 Analysis of SEM Aerosol Data.........................................................102 Analysis of XRD Bulk Data .............................................................104 Analysis of XRD XRF Data .............................................................107 iviv Chapter Page Analysis of Geological Maps............................................................112 Research Questions and Hypothesis .................................................112 V. SUMMARY, CONCLUSIONS, AND RECOMMENDATIONS ...........116 Summary..........................................................................................116 Conclusions......................................................................................117 Recommendations ............................................................................118 BIBLIOGRAPHY ...................................................................................................120 APPENDIXES ........................................................................................................138 APPENDIX A - MAPS OF AFRICA, CHAD, AND BODELE.......139 APPENDIX B - SATELLITE IMAGES OF THE BODELE...........142 APPENDIX C - SEM DATA FOR BULK SAMPLES....................146 APPENDIX D - SEM IMAGES FOR BULK SAMPLES................195 ` APPENDIX E - SEM DATA FOR AEROSOL SAMPLES ............219 APPENDIX F SEM IMAGES FOR AEROSOL SAMPLES ........235 APPENDIX G - XRD DATA FOR BULK SAMPLE......................242 APPENDIX H - TECHNOLOGY FOR XRD XRF .........................245 v LIST OF TABLES Table Page 1. Annual Source Strength............................................................................47 2. Primary Particle Emissions.......................................................................49 3. Aerosol Sulfates Precursors......................................................................69 4. Atomic % and Weight % Bulk Sample Analyses......................................99 5. Elemental Weight % Analyses for Crustal Materials ..............................100 6. Actual SEM Bulk Data Chemical Analyses............................................101 7. Elemental Table of Clay Mineral Elements for Crustal Material on Earth..................................................................102 8. Atomic % and Weight % Aerosol Sample Analyses ...............................103 9. Actual SEM Aerosol Data Chemical Analyses .......................................104 10. Bodele Semi-Quantitative Mineral Analysis...........................................104 vi LIST OF FIGURES Figure Page 1, Bodele Depression, Chad in Africa...........................................................3 2. Saltation of Sediments ..............................................................................31 3. Particle Size Classification........................................................................32 4. Yardang Linear Features...........................................................................34 5. Dune Types ..............................................................................................34 6. Bodele Depression, Chad..........................................................................37 7. Particle Size Suspension and Wind Velocity.............................................38 8. Trade Wind Patterns of North Africa ........................................................39 9. Harmattan Wind Diagram.........................................................................40 10. Model Simulated Column Averages of Cloud Fraction with T> 253° K.........................................................................................43 11. Annual Average Aerosol Source Strength.................................................51 12. Observed and Model-predicted Annual Average Sulphate Concentrations..........................................................................................53 13. Observed and Model-predicted Annual Average Concentrations of Sea-salt.................................................................................................53 14. Simulated Surface Mass Concentrations of Dust Particles.........................54 15. Extinction Efficiency and Single Scattering Albedo..................................57 16. Aerosol Optical Depth ..............................................................................58 17. Variations of Single Scattering Albedo .....................................................60 vii Figure Page 18. Monthly Averages of Simulated First Direct Forcings...............................62 19. Observed and Simulated Concentrations of Black Carbon.........................63 20. Observed and Simulated Organic Carbon..................................................63 21. Sulphate Aerosols.....................................................................................71 22. Gondwana ................................................................................................76
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