University of Tennessee, Knoxville TRACE: Tennessee Research and Creative Exchange Doctoral Dissertations Graduate School 5-2021 Biotic and Abiotic Dehalogenation of Halogenated Methanes: Trichlorofluoromethane, Dichlorodifluoromethane, and Tetrachloromethane Briana M. McDowell The University of Tennessee, Knoxville, [email protected] Follow this and additional works at: https://trace.tennessee.edu/utk_graddiss Part of the Environmental Microbiology and Microbial Ecology Commons Recommended Citation McDowell, Briana M., "Biotic and Abiotic Dehalogenation of Halogenated Methanes: Trichlorofluoromethane, Dichlorodifluoromethane, and Tetrachloromethane. " PhD diss., University of Tennessee, 2021. https://trace.tennessee.edu/utk_graddiss/6692 This Dissertation is brought to you for free and open access by the Graduate School at TRACE: Tennessee Research and Creative Exchange. It has been accepted for inclusion in Doctoral Dissertations by an authorized administrator of TRACE: Tennessee Research and Creative Exchange. For more information, please contact [email protected]. To the Graduate Council: I am submitting herewith a dissertation written by Briana M. McDowell entitled "Biotic and Abiotic Dehalogenation of Halogenated Methanes: Trichlorofluoromethane, Dichlorodifluoromethane, and Tetrachloromethane." I have examined the final electronic copy of this dissertation for form and content and recommend that it be accepted in partial fulfillment of the requirements for the degree of Doctor of Philosophy, with a major in Microbiology. Frank E. Löeffler, Major Professor We have read this dissertation and recommend its acceptance: Steve Wilhelm, Karen Lloyd, Claudia Rawn, Mircea Podar Accepted for the Council: Dixie L. Thompson Vice Provost and Dean of the Graduate School (Original signatures are on file with official studentecor r ds.) Biotic and Abiotic Dehalogenation of Halogenated Methanes: Trichlorofluoromethane, Dichlorodifluoromethane, and Tetrachloromethane. A Dissertation Presented for the Doctor of Philosophy Degree The University of Tennessee, Knoxville Briana M. McDowell May 2021 Copyright © 2021 by Briana M. McDowell. All rights reserved. ii Abstract Trichlorofluoromethane (CFC-11), dichlorofluoromethane (CFC-12), and tetrachloromethane (CT) are fully halogenated methanes that were produced as refrigerants in the early part of the 1900s and later used in many industrial processes. They are ozone-depleting agents and common groundwater contaminants. They are volatile chemicals that are moderately soluble in water. Due to their volatility when released to the environment, they are predominantly found in the atmosphere, though they also dissolve into the groundwater. In anaerobic environments, they can undergo dehalogenation reactions with several redox-active compounds. This dissertation presents results from two treatability studies from sites contaminated with CFC-11, CFC-12, and CT. Additionally, the effect of pH on the dehalogenation of CFC-11, CFC-12, and CT is examined, and a sulfidogenic enrichment culture grown in the presence of CT is characterized. The first treatability study indicates that the addition of reactive iron species (i.e., zero-valent iron or ferrous sulfide) combined with the bioaugmentation culture KB-1 Plus and lactate can facilitate the transformation of CT into non- halogenated end products. The most effective remediation strategy for CT observed during the treatability study for the second contaminated site was the addition of zero- valent iron; this facilitated the transformation of CT to chloroform (CF). CF is a non- desirable end product, and additional remediation efforts are recommended for the second contaminated site. A shift in the type of transformation products formed during the reduction of CFC-11, CFC-12, or CT by super-nucleophilic cobalamin was observed as pH increased. Mackinawite and vivianite were identified as the two precipitate phases formed in the presence of the sulfidogenic enrichment culture. Vivianite formation likely occurs via precipitation with the phosphate present in the medium, and that mackinawite forms via precipitation with hydrogen sulfide produced by the sulfidogenic bacteria present in the enrichment. Additionally, a greater decline in CT was observed in microcosms that contained active enrichment culture than in heat-killed controls, suggesting that the consortium aids in the degradation of CT, probably via mackinawite formation, as it is a reactive iron species. iii Table of Contents INTRODUCTION .............................................................................................................. 1 CHAPTER I ........................................................................................................................ 2 Transformation of Trichlorofluoromethane, Dichlorodifluoromethane, and Tetrachloromethane by Biotic and Abiotic Processes: A Review ...................................... 2 Abstract ........................................................................................................................... 3 Production, use, and occurrence in the environment. ................................................. 3 Toxicology. ................................................................................................................. 4 Physical and chemical properties. ............................................................................... 4 Fate and longevity in environmental systems. ............................................................ 4 Degradation pathways. ................................................................................................ 5 Hydrogenolysis. .......................................................................................................... 6 Radical-radical coupling. ............................................................................................ 6 Free radical addition to alkenes. ................................................................................. 6 Combination reactions. ............................................................................................... 6 Carbene hydrolysis. ..................................................................................................... 6 Surface associated carbene reduction. ........................................................................ 7 Transformation of CFC-11, CFC-12, and CT. ............................................................ 7 Organometallic cofactors. ........................................................................................... 7 Extracellular electron shuttles. .................................................................................... 8 Siderophores. .............................................................................................................. 9 Conclusions and Future Work. ................................................................................... 9 Appendix A ................................................................................................................... 10 Reaction equations. ................................................................................................... 17 CHAPTER II ..................................................................................................................... 18 High-resolution site charaterization and Laboratory-Scale Treatability Study enabling aquifer remediation at an Industrial Site. .......................................................................... 18 Abstract ......................................................................................................................... 19 Introduction ................................................................................................................... 19 Methods......................................................................................................................... 20 Membrane Interface Probe-Hydraulic Profiling Tool (MiHPT) Logging. ............... 20 Aquifer Material Sampling. ...................................................................................... 21 Groundwater Sampling. ............................................................................................ 21 Borehole Abandonment. ........................................................................................... 22 Volatile Organic Compounds (VOC) analysis. ........................................................ 22 Total Iron Measurements. ......................................................................................... 23 Quantitative Polymerase Chain Reaction (qPCR). ................................................... 23 Microcosm Setup and Monitoring. ........................................................................... 23 Standard Curve Preparation of Gas Chromatograph Equipped with a Flame Ionization Detector (GC-FID) and Gas Chromatograph Equipped with a Micro- Electron Capture Detector (GC-µECD). ................................................................... 26 Data Management. .................................................................................................... 26 Results ........................................................................................................................... 27 iv MiHPT Overview. ..................................................................................................... 27 Borehole A1 (BHA1)—MiHPT Data. ...................................................................... 27 Borehole A2