Enhanced Environmental Detection of Uranyl Compounds Based on Luminescence Characterization
Total Page:16
File Type:pdf, Size:1020Kb
Virginia Commonwealth University VCU Scholars Compass Theses and Dissertations Graduate School 2009 ENHANCED ENVIRONMENTAL DETECTION OF URANYL COMPOUNDS BASED ON LUMINESCENCE CHARACTERIZATION Jean Nelson Virginia Commonwealth University Follow this and additional works at: https://scholarscompass.vcu.edu/etd © The Author Downloaded from https://scholarscompass.vcu.edu/etd/2000 This Dissertation is brought to you for free and open access by the Graduate School at VCU Scholars Compass. It has been accepted for inclusion in Theses and Dissertations by an authorized administrator of VCU Scholars Compass. For more information, please contact [email protected]. Jean D. Nelson 2009 All Rights Reserved ENHANCED ENVIRONMENTAL DETECTION OF URANYL COMPOUNDS BASED ON LUMINESCENCE CHARACTERIZATION A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at Virginia Commonwealth University. by Jean Dennis Nelson Master of Science, Virginia Commonwealth University, 2001 Bachelor of Science, Radford University, 1999 Director: John E. Anderson Associate Professor, Department of Biology Virginia Commonwealth University Richmond, Virginia December, 2009 ii ACKNOWLEDGMENT First and foremost, I would like to thank the members of my dissertation committee: Dr. John Anderson, Dr. Gary Tepper, Dr. Charles (Mike) Reynolds, Dr. Lemont Kier and Dr. David Edwards. They were each an endless source of support, patience and guidance. There are several of my teammates I would like to thank. Specifically, I am grateful to Jarrod Edwards for all his assistance in collection of the soil samples. Further, I am grateful to Ricky Massaro for his assistance with generating the spectral scores using MATLAB software. In general, I am thankful to all my co-workers for being so supportive and understanding throughout the years. In addition, I would like to thank Dr. Dmitry Pestov and Ken Chen of VCU Engineering for their assistance during all the preliminary studies and guidance with regards to selection of the distributable enhancing material. I extend my gratitude to A&L Eastern Laboratories, Inc. for conducting several of the soil analyses, and specifically to Dr. Paul Chu for taking the time to discuss the analytical procedures with me. I am also appreciative to the ERDC Environmental Lab (EL), specifically to members of the Environmental Chemistry Branch for further analysis of my soil samples, in addition to Dr. Vic Medina and Dr. Afrachanna Butler for supplying the YPG soil and discussing soil preparation procedures. I am grateful to my employer, the Engineer Research and Development Center (ERDC), and further to the DoD, for supporting me financially and morally throughout my research and for providing me with the long-term training opportunity. This research project was supported in part by a DOE NA22 grant (DE-FG52-06NA27491). Also, I am very grateful to VCU Life Sciences, for creating the Integrative Life Sciences program, enabling Ph.D. students to partake in such an interdisciplinary approach to coursework and research, and also for being supportive of me over the last six years. Finally, I extend my deepest gratitude and appreciation to my family, especially to my husband Dan, my daughters Kayleigh and Allison, and to my mother; for their endless source of love and support. Last, but most importantly, I thank God for providing me with the strength, patience and perseverance I needed. iii TABLE OF CONTENTS List of Tables...................................................................................................................................v List of Figures...............................................................................................................................viii List of Abbreviations....................................................................................................................xiii Abstract..........................................................................................................................................xv CHAPTER 1: INTRODUCTION – REVIEW...............................................................................1 2+ 1.1 Introduction to Uranium and the Uranyl Ion (UO 2 )...................................................1 1.2 Uranium Contamination in the Environment................................................................9 1.3 Luminescence Detection and Characterization of Uranyl..........................................19 1.4 Uranium Extraction and Fluorescence Enhancement.................................................23 1.5 Remote Sensing of Uranium.......................................................................................28 1.6 Comprehensive Mission Statement.............................................................................29 1.7 Key Features of Environmental Samples....................................................................33 1.7.1 Introduction................................................................................................33 1.7.2 Soil Texture................................................................................................35 1.7.3 Moisture Content and Water Potential.......................................................39 1.7.4 pH Related Effects.....................................................................................44 1.7.5 Soil Organic Matter (SOM).......................................................................54 1.7.6 Iron Content...............................................................................................61 1.7.7 Summary and Hypothesis Statements........................................................68 iv CHAPTER 2: EMPIRICAL INVESTIGATIONS........................................................................73 2.1 Preliminary Studies.....................................................................................................73 2.1.1 Introduction................................................................................................73 2.1.2 Steady-state Fluorescence Spectroscopy...................................................76 2.1.3 Data Related to Key Features of Environmental Samples.........................77 2.2 Research Design..........................................................................................................91 2.2.1 Introduction................................................................................................91 2.2.2 Luminescence Detection and Spectral Scoring – Test Dataset..................92 2.2.3 Experiments for Testing Hypotheses.......................................................102 2.3 Comprehensive Experimental Matrix and Data Analysis.........................................106 2.3.1 Introduction..............................................................................................106 2.3.2 Statistical Variables.................................................................................109 2.3.3 Response (Y) Variables……………………………...............................113 2.3.4 Populations of Spectra – Achieving Desired Detection Thresholds…....117 2.3.5 Predictor (X) Variables – Relationships……..........................................125 2.3.6 Predictor (X) and Response (Y) Variables – Bivariate Relationships….127 2.3.7 Development of Predictive Models for the Comprehensive Dataset…...145 2.3.8 Multivariate Regression………………………...………………………154 2.3.9 Final Discussion…………………………………………………...……156 Literature Cited............................................................................................................................160 Vita……………...........................................................................................................................171 v LIST OF TABLES Page Table 1. General background information for Uranium................................................................2 Table 2. Key molecular processes pertinent to the fluorescence spectroscopy of U(VI). Refer also to Figure 4. Adapted from (Meinrath 1997).................................................7 Table 3. Names and chemical formulas for commonly studied Uranium (VI) minerals. Adapted from (Morris, Allen et al. 1996).....................................................................12 Table 4. Reference information for estimates of uranium concentrations (ppm) in environmental soil samples........................................................................................................16 Table 5. Key mechanisms by which U mobility can be retarded in the surface and subsurface geologic environment. Adapted from (Duff, Coughlin et al. 2002)...........................34 Table 6. Standard soil pH classifications. Adapted from USDA NRCS public information..........................................................................................................................45 Table 7. Reference information for pH levels in environmental soil samples used in U studies............................................................................................................................46 Table 8. Chemical formulas for commonly encountered hydroxyl and carbonate forms of U(VI) in aqueous phases and corresponding optimal pH values....................................48 Table 9. Summary of U sorption, dissolution and diffusion studies and their findings associated with pH changes.............................................................................................50 Table 10. Descriptions for the room temperature fluorescence