{Replace with the Title of Your Dissertation}

FATE AND DEGRADATION OF PETROLEUM HYDROCARBONS IN STORMWATER BIORETENTION CELLS A DISSERTATION SUBMITTED TO THE FACULTY OF THE GRADUATE SCHOOL OF THE UNIVERSITY OF MINNESOTA BY GREGORY HALLETT LEFEVRE IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY Paige J. Novak, Advisor Raymond M. Hozalski, Advisor August 2012 © Gregory H. LeFevre 2012 Acknowledgements There are many people without whom this work or even arriving at this place would not have been possible. First, there are those who provided invaluable academic support throughout my time at the University of Minnesota. I could not have done this without the support, guidance, nurture, and encouragement of my advisors, Paige Novak and Ray Hozalski. They have been very patient intellectual shepherds and allowed me to grow as a researcher. My committee members, Tim LaPara, John Nieber, and John Gulliver have taught me much in their classes, broader implications of my research, and constructive critiques. My many labmates in the Novak and Hozalski groups have provided useful laboratory instruction, constructive feedback, and hours of pleasant interaction. Second, I must acknowledge the sources of funding which made this work and my graduate school career possible. The funding from the National Science Foundation Graduate Research Fellowship Program (GRFP) and Integrative Graduate Education and Research Traineeship (IGERT, DGE-0504195) has allowed me to pursue my own research interests and learn from those in complimentary fields. I am also indebted to the Graduate School and to the Minnesota chapter of the Achievement Rewards for College Scientists (ARCS) Foundation for their student support. Funding for our research supplies also came from the Minnesota Water Resources Center. Finally, this work would not have been possible without the unending support of my family. Foremost, my wife Nancy-Jeanne has been there every step of the way all the while tolerating, encouraging, and supporting with unconditional love. I absolutely cannot say this enough. My parents, Bob and Cathy, have always provided the gumption, work ethic, drive, and perspective that are necessary to succeed in life. My brother Kevin has also been a source of continued sibling support during this experience. Lastly, I’d like to thank John Gierke, professor at Michigan Tech, for believing in me from day one and continuing to be a true mentor. i Abstract This dissertation describes the investigation of the fate of hydrocarbons in stormwater bioretention areas and those mechanisms that affect hydrocarbon fate in such systems. Seventy-five samples from 58 bioretention areas were collected and analyzed to measure total petroleum hydrocarbon (TPH) residual and biodegradation functional genes. TPH residual in bioretention areas was greater than background sites but low overall (<3 µg/kg), and well below either the TPH concentration of concern or the expected concentration, assuming no losses. Bioretention areas with deep-root vegetation contained significantly greater quantites of bacterial 16S rRNA genes and two functional genes involved in hydrocarbon biodegradation. Field soils were capable of mineralizing naphthalene, a polycyclic aromatic hydrocarbon (PAH) when incubated in the laboratory. In an additional laboratory investigation, a column study was initiated to comprehensively determine naphthalene fate in a simulated bioretention cell using a 14C- labeled tracer. Sorption to soil was the greatest sink of naphthalene in the columns, although biodegradation and vegetative uptake were also important loss mechanisms. Little leaching occurred following the first flush, and volatilization was insignificant. Significant enrichment of naphthalene degrading bacteria occurred over the course of the experiment as a result of naphthalene exposure. This was evident from enhanced naphthalene biodegradation kinetics (measured via batch tests), significant increases in naphthalene dioxygenase gene quantities, and a significant correlation observed between naphthalene residual and biodegradation functional genes. Vegetated columns outperformed the unplanted control column in terms of total naphthalene removal and ii biodegradation kinetics. As a result of these experiments, a final study focused on why planted systems outperform unplanted systems was conducted. Plant root exudates were harvested from hydroponic setups for three types of plants. Additionally, a solution of artificial root exudates (AREs) as prepared. Exudates were digested using soil bacteria to create metabolized exudates. Raw and metabolized exudates were characterized for dissolved organic carbon, specific UV absorbance, spectral slope, florescence index, excitation-emission matrices, and surface tension. Significant differences on character were observed between the harvested exudates and the AREs, as well as between the raw and metabolized exudates. Naphthalene desorption from an aged soil was enhanced in the presence of raw exudates. The surface tension in samples containing raw harvested exudates was reduced compared to samples containing the metabolized exudates. Plant root exudates may therefore facilitate phytoremediation by enhancing contaminant desorption and improving bioavailability. Overall, this resarch concludes that heavily planted bioretention systems are a sustainable solution to mitigating stormwater hydrocarbon pollution as a result of likely enhanced contaminant desorption, and improved biodegradation and plant uptake in such systems. iii Table of Contents ACKNOWLEDGEMENTS .............................................................................................. I ABSTRACT ...................................................................................................................... II TABLE OF CONTENTS ............................................................................................... IV LIST OF TABLES .......................................................................................................... VI LIST OF FIGURES ...................................................................................................... VII CHAPTER 1: INTRODUCTION .................................................................................... 1 1.1 STORMWATER RUNOFF AND POLLUTION .................................................................... 1 1.2 HYDROCARBON POLLUTION IN STORMWATER ........................................................... 1 1.3 BIORETENTION TECHNOLOGY .................................................................................... 4 1.4 FATE OF PETROLEUM HYDROCARBONS IN BIORETENTION AREAS ............................. 7 1.5 OBJECTIVES ............................................................................................................... 8 1.6 REFERENCES ............................................................................................................ 11 CHAPTER 2: LITERATURE REVIEW ..................................................................... 23 2.1 POTENTIAL HYDROCARBON REMOVAL MECHANISMS IN BIORETENTION AREAS ..... 23 2.2 BIODEGRADATION OF PETROLEUM HYDROCARBONS ............................................... 28 2.3 MICROBIAL DEGRADATION PATHWAYS ................................................................... 29 2.4 INFLUENCE OF VEGETATION ON IN SITU HYDROCARBON DEGRADATION ................ 32 2.5 BIOAVAILABILITY OF ORGANIC POLLUTANTS .......................................................... 34 2.6 SUMMARY AND RESEARCH NEEDS ........................................................................... 37 2.7 REFERENCES ............................................................................................................ 38 CHAPTER 3: THE ROLE OF BIODEGRADATION IN LIMITING THE ACCUMULATION OF PETROLEUM HYDROCARBONS IN RAINGARDEN SOILS ............................................................................................................................... 49 3.1 INTRODUCTION................................................................................................... 51 3.2 MATERIALS AND METHODS ............................................................................ 54 3.3 RESULTS AND DISCUSSION .............................................................................. 61 3.4 CONCLUSIONS ..................................................................................................... 74 3.5 REFERENCES ........................................................................................................ 75 CHAPTER 4: FATE OF NAPHTHALENE IN LABORATORY-SCALE BIORETENTION CELLS: IMPLICATIONS FOR SUSTAINABLE STORMWATER MANAGEMENT.............................................................................. 83 4.1 INTRODUCTION................................................................................................... 85 4.2 MATERIALS AND METHODS ............................................................................ 87 4.3 RESULTS ............................................................................................................... 93 4.4 DISCUSSION ....................................................................................................... 107 4.5 REFERENCES ...................................................................................................... 112 iv CHAPTER 5: ROOT EXUDATE IMPACTS ON CONTAMINANT DESORPTION AND BIODEGRADATION ......................................................................................... 122 5.1 INTRODUCTION................................................................................................

Load more