1 an Investigation of Fertilizer-Derived Uranium in Ohio
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An Investigation of Fertilizer-Derived Uranium in Ohio Agricultural Soils Thesis Presented in Partial Fulfillment of the Requirements for the Degree Master of Science in the Graduate School of The Ohio State University By Adolfo Eberhard Calero, B.S. Graduate Program in Earth Sciences The Ohio State University 2020 Thesis Committee Dr. W. Berry Lyons, Advisor Dr. Nicholas T. Basta Dr. Rattan Lal 1 Copyrighted by Adolfo Eberhard Calero 2020 2 Abstract The evolution of modern agricultural practices as a result of a growing global population has led to increases in the flux of agricultural chemicals and compounds to both natural waters and soils. The most studied of these impacts are the addition of nitrogen (N) and phosphorus (P) through the application of chemical fertilizers, leading to their increase in surface runoff from agricultural operations, causing eutrophication in natural waters. Uranium (U) is a trace element that is often associated with P-rich fertilizer use, having the potential to accumulate in soils, crops, and surface waters, due to its natural occurrence in phosphate rock, along with various weathering and erosional processes that make it mobile. Studies have suggested phosphorus fertilizer is a source of uranium contamination in natural waters and soils. This study investigates chemistry of agricultural soils treated with P-fertilizer and compares them with the chemistry of agricultural soils under different management practices. This study also characterizes historical Geographic Information System (GIS) data in order to correlate uranium concentrations in Ohio soils with Ohio’s glaciated compared to non-glaciated surfaces, underlying bedrock geology, and current land use/land cover. Total U concentrations in the soils ranged from 2.7 – 5.4 µg/g, and the water-, base-, and acid-soluble concentrations of U ranged from 2.2 x 10-4 – 1.4 x 10-3, 0.09 – 0.58, and 0.27 – 0.76 µg/g, respectively. The average concentration of the sum of the U in each of the i soluble/extractable phases gave a maximum value of 18% of the total U. Using previously published data from the USGS, there are higher U concentrations in soils from the glaciated portion of the State, as opposed to those from the unglaciated portion of Ohio. This research clearly demonstrates that soils having fertilizer application show no statistical difference in U compared to similar soils without fertilizer application. ii Acknowledgments I would like to express my sincere appreciation to Dr. Berry Lyons for his infinite patience, encouragement, and for giving me the opportunity to perform research in both Ohio and Antarctica. I would also like to extend my deepest gratitude to Melisa Diaz for being an amazing friend, scientist, and for providing me with the opportunity to communicate my research. I would like to thank Dr. Nick Basta, for being on my committee, for helping deepen my understanding of soils and soil chemistry, and for running dichromate analyses on my samples. I would also like to thank Dr. Rattan Lal for being on my committee, and for providing me access to his plots at Waterman Farm. I am extremely grateful to Dr. Chris Gardner for all of his advice regarding statistics and data presentation, as well as for bringing me to help with research in Antarctica. Thank you to Dr. Sue Welch for helping me with SEM analysis and for providing me with advice on any questions I had about lab work. I would also like to thank Dr. Steve Culman and Bethany Herman for providing me with soil samples, as well as answers to any questions I had about them. Thank you to Devin Smith for spending a couple of early mornings with me at Waterman Farm to help with sample collection. Thanks to the Trace Element Research Lab, especially Anthony Lutton, for helping me with the analyses of my samples. Thank you to Dr. Anne Carey for the use of her lab space. Thanks to Nall Moonilall for providing me with the locations and with all the information regarding the iii plots at Waterman Farm. Thanks to Brianna Piergallini for helping me with my GIS maps. I would also like to thank the Geological Society of America and the Friends of Orton Hall for providing me with funding for this thesis work. Thanks to Dr. Seth Young for encouraging me to pursue a graduate degree and to work in a great research program. Last, I would like to thank my family for their love and support throughout my graduate experience. iv Vita September 15th, 1996……………………………..Born – Miami, Florida August 2018………………………………………B.S. Geology, Florida State University August 2018 to Present…………………………..Graduate Research and Teaching Associate, School of Earth Sciences, The Ohio State University Fields of Study Major Field: Earth Sciences v Table of Contents Abstract ................................................................................................................................ i Acknowledgments.............................................................................................................. iii Vita ...................................................................................................................................... v List of Tables ................................................................................................................... viii List of Figures .................................................................................................................. xiii Chapter 1. Introduction ....................................................................................................... 1 1a. U in Soils; General Considerations ........................................................................... 3 1b. Previous Work .......................................................................................................... 6 1c. Potential Human Impacts .......................................................................................... 8 1d. Rationale for Research .............................................................................................. 9 1e. Hypothesis ............................................................................................................... 10 Chapter 2. Study Areas ..................................................................................................... 11 2a. Waterman Farm ....................................................................................................... 11 2b. “Wooster” Sites ....................................................................................................... 12 2c. Coshocton ................................................................................................................ 13 Chapter 3. Methods ........................................................................................................... 15 3a. Cleaning Plasticware ............................................................................................... 15 3b. Sampling and Processing ........................................................................................ 15 3c. Extractions............................................................................................................... 16 3d. U-Analysis .............................................................................................................. 19 3e. Precision and Accuracy ........................................................................................... 20 3f. pH Analysis ............................................................................................................. 20 3g. Loss on Ignition ...................................................................................................... 21 3h. XRF Analysis .......................................................................................................... 22 3i. GIS Maps ................................................................................................................. 23 3j. Scanning Electron Microscopy ................................................................................ 24 Chapter 4. Results ............................................................................................................. 25 4a. USGS and NURE Ohio GIS Map Observations ..................................................... 25 4b. Loss on Ignition for Samples .................................................................................. 28 vi 4c. pH Values for Samples............................................................................................ 29 4d. XRF Data – Impact of Weathering on U Concentrations in Soils .......................... 30 4e. Uranium Concentrations in Soils ............................................................................ 32 4f. Uranium-Bearing Minerals in Soils ......................................................................... 39 Chapter 5. Discussion ....................................................................................................... 41 5a. Relationship of LOI and pH to U Concentrations in Soils...................................... 41 5b. Extractions – Water vs. Base vs. Acid .................................................................... 42 5c. U Concentrations in Ohio Soils: Based on a Datamining and GIS Approach ........ 44 5d. Comparison of Agricultural Management Practices in Relation to U Concentrations in Agricultural Soils ...................................................................................................... 47 5e. Comparison of Ohio U Soil Chemistry to US and Global Inventories