UNIVERSITY OF CINCINNATI Date: 11/15/2005 I, Alejandra Bonilla___________________________________________, hereby submit this work as part of the requirements for the degree of: Master of Science in: Geology It is entitled: Geochemistry of Arsenic and Sulfur in Southwest Ohio: Bedrock, Outwash Deposits and Groundwater. This work and its defense approved by: Chair: Dr. Barry J. Maynard Dr. David B. Nash Dr. Warren D. Huff “Geochemistry of Arsenic and Sulfur in Southwest Ohio: Bedrock, Outwash Deposits and Groundwater” A thesis submitted to the Division of Research and Advanced Studies of the University of Cincinnati in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE in the Department of Geology of the College of Arts and Sciences 2005 by Alejandra Bonilla Ramos. B.S., Universidad Nacional Autónoma de México, 2002 Committee Chair: Dr. Barry J. Maynard ABSTRACT Located in southwest Ohio, the Mason and also the Lebanon Correctional Institute (LeCI) drinking water distribution systems obtain their water from the Shaker Creek “buried valley” Aquifer. The Pleistocene valley contains glacial outwash material and some lake clays incised into the limestone-shale bedrock. Analyses were done in water, aquifer material and bedrock samples. The results of arsenic in water ranged from 4-18 µg/L, and show that many of these samples are above the USEPA MCL. Thus, both systems have concerning arsenic levels. Arsenic analyses in the bedrock and glacial outwash material ranged from 4-40 ppm. Therefore, arsenic in the groundwater could be sourced from the glacial aquifer material and/or from the surrounding bedrock. The bedrock geology of the area of study consists of Upper Ordovician-Lower Silurian limestones and shales of southern Ohio and northern Kentucky. The bedrock formation studied and that partly influence the water chemistry in the Shaker Creek buried aquifer is the Kope Formation. Stable isotope analysis of sulfur was used for this study. Many of the geochemical characteristics of arsenic are analogous to those of sulfur, because both elements occur in reduced and oxidized forms and the oxidation states change as a result of biological processes. Biogenic reduction is the dominant form of sulfur fractionation in nature and is mainly a product of sulfur reducing bacteria. The present thesis is focused in two main parts. First part covers the study of arsenic in solids and sulfur isotopes were used to calculate sedimentation rates in the Kope Formation. Second part includes the study of arsenic in groundwater and its source in the Shaker Creek Aquifer. This study presents a model of the possible sources and mechanisms of arsenic in groundwater. Sulfur isotopes were used to provide a chemical i assessment and a comparison of sulfur isotopes in the bedrock with dissolved sulfur in the aquifer as a test for arsenic release by pyrite dissolution. ii ACKNOWLEDGMENTS I want to express my deepest gratitude to the Department of Geology, University of Cincinnati for all the financial and moral support for my Masters project through the Wycoff Scholarship and summer URC. The laboratory expenses for this project were supported from Sigma Xi and Geological Society of America. The Mexican government trough the Secretaria de Educaciόn Pública (SEP) and Consejo Nacional de Ciencia y Tecnologia (CONACYT), which granted with a complementary scholarship. Such support makes possible that Mexican students are able to study abroad. I thank my advisor, Dr. Barry Maynard, for his guidance and support. Since our first communication he showed that even his multiples occupations he is always assisting and encouraging his students in all kind of aspects. I thank the members of my committee: Dr. David Nash and Dr. Warren Huff for their valuable suggestions and comments to the present thesis. My appreciation for their patience and invaluable time for correcting and suggestions to my writings and proposals: Susie Taha, Dr. Warren Huff, Dr. Tammie Gerke and Phil Hart. This project was also possible with the help and assistance for collecting and processing samples: Erika Elswick, Indiana University, Greg Davis, Lebanon Correctional Institute, Bruce Whitteberry, Greater Cincinnati Water Works and Dr. Carl Brett, University of Cincinnati. A special thanks to Ana Londoño not only for her great friendship but for all her moral and academic support during my studies. My thousand thanks to my friends who made an unforgettable and amazing experience my life in Cincinnati: Chie Suzuki, Pablo Rosales, Orla Keyes, Hari Prashadan, Xavier Beteta, Giovanni Contreras, Jorge Jaramillo, Zheng Wang, Arjun Santhanam, Carmen Espinoza, Utku Solpuker and John Byron Baena. All my love and gratefulness to my family: my dad Arturo, Adriana, Carla, Ernesto, Claudia and Alicia. iii TABLE OF CONTENTS Abstract ii Acknowledgments iii Table of Contents iv List of Figures vi List of Tables ix INTRODUCTION 1 PART I Geochemistry of Arsenic and Sulfur of the Kope Formation 4 in Southwestern Ohio 1.1. Introduction 5 1.2. Geology 10 1.2.1 Submembers of the Kope Formation 11 1.2.2 Paleogeography and genesis of the bedding in the Kope Formation 11 1.3. Methods 14 1.3.1 Geochemistry 14 1.3.1.1 Solids 14 1.3.1.2 Sulfide analyses 15 1.4. Results 19 1.4.1 XRF Results 30 1.5. Interpretations 33 1.6. Conclusions 41 PART II The Kope Formation as a Source of Arsenic and Sulfur 42 in Groundwater in Southwestern Ohio. 2.1. Introduction 43 iv 2.1.1 Statement of the problem 46 2.1.2 Background 49 2.1.3 History of glaciations and associated deposits 53 2.1.4 Shaker Creek Aquifer 53 2.2. Arsenic chemistry 55 2.2.1 Arsenic in groundwater 58 2.3. Methods 59 2.3.1 Solids 59 2.3.2 Groundwater sampling 59 2.3.3 Sulfide analyses 60 2.3.3.1 Sulfate precipitation 60 2.4. Results 64 2.4.1 Sulfur isotopes results 79 2.5. Sulfur isotopes 82 2.6. Interpretations 86 2.7. Conclusions 94 References 96 v LIST OF FIGURES Figure No. Page No Part I 1.1. Location of the area of study and bedrock sampled 7 1.2. Diagram of the generalized Upper Ordovician stratigraphy of southwestern Ohio and northern Kentucky known as the Cincinnatian Series 8 1.3. Geologic map of Southwest part of Ohio conformed by Butler, Warren, Hamilton and Clermont Counties 9 1.4. The Kope Formation with the respective five submembers: Snag Creek, Alexandria, Grand View, Grand Avenue and Taylor Mill 13 1.5. Diagram of the sulfur extraction system used in the geochemistry laboratory in the Department of Geology 17 1.6. Peaks of arsenic concentrations in the Kope Formation in the outcrop at Kentucky route 445 20 1.7. Arsenic results obtained from the Clermont County well 21 1.8. Arsenic levels in the Rapid Run Creek Section 29 1.9. Aluminum concentrations versus δ34S in samples from the Kope Formation 31 1.10. Calcium concentrations versus δ34S in samples from the Kope Formation 32 1.11. Range of δ34S in different shales, limestone, biogenic pyrite and sea water 35 1.12. Diagram of sulfur fractionation 36 1.13. Relationship of the sulfur fractionation and rate of sulfate-pyrite reduction by bacteria in marine sediments 40 vi Figure No. Page No Part II 2.1. Map of United States showing locations and arsenic concentrations for groundwater sampled by the USGS and state agencies 45 2.2. Map of the area of study and sampling areas in Ohio and Kentucky. 48 2.3. Surficial geology of the southwesterm part of Ohio 51 2.4. Geology of the Shaker Creek Aquifer 52 2.5. pE-pH diagram for predominant arsenic species in groundwater systems 56 2.6. Molecular difference between arsenate [As5+] and arsenite [As3+] 57 2.7A. Bowser-Morner using a rotosonic rig in the LeCI prior to the drilling 62 2.7B. Sample of aquifer material recovered and packed in a box 62 2.8. Diagram of the sulfur extraction system used in the geochemistry laboratory in the Department of Geology for solids 63 2.9. Recovered log from the Lebanon Correctional Institute 66 2.10. Arsenic concentrations in the Lebanon Correctional Institute aquifer material 67 2.11. Average Oxidation Potential Reduction of Shaker Creek Aquifer wells and its relation with time 72 2.12. Iron increased with time from 1997 to 2004 in LeCI and Mason wells 73 2.13. Manganese increased with time from 1997 to 2004 in LeCI and Mason wells 74 2.14. Relationship between arsenic and total ORP in LeCI and Mason monitoring wells 75 2.15. Relations between sulfate and arsenic in LeCI and Mason monitoring wells 76 vii Figure No. Page No 2.16. Chloride and sodium relationship in the Mason and LeCI wells 77 2.17. Range of δ34S in different shales, limestone, biogenic pyrite and sea water 84 2.18. Isotopic systematics of sulfur fractionation in groundwater 85 2.19. Scheme of the Shaker Creek Aquifer and the chemical reactions occurring within 88 2.20. Diagram of the possible interactions between δ34S isotopes and redox conditions occurring in the aquifer depending on the time with pyrite 89 2.21. Possible interactions in the aquifer between δ34S isotopes, redox conditions with time for arsenopyrite 90 2.22. Hydrograph of monthly fluctuations in water-table elevation from a well of the Shaker Creek Aquifer 93 viii LIST OF TABLES Table No Page No Part I 1.1. Relation of majors from XRF analysis and sulfur isotopes relation from bedrock samples of the Kope Formation in the section area of KY route 445 22 1.2. Whole-rock chemistry of trace elements and arsenic concentrations of the Kope Formation in the area of Kentucky Route 445 23 1.3.