Arsenic speciation in the presence of anoxic mixed valent iron systems

ii To my parents for nurturing my creative and academic pursuits iii Success is the sum of small efforts, repeated day in and day out. iv ACKNOWLEDGMENTS I would like to thank Jay Thompson and David Peate for their generosity with the ICP-MS. Jay played a crucial role in developing the arsenic analytical method, and always provided me with a tuned and sensitive instrument for sample analysis. I would also like to thank Ed O'Loughlin, Max Boyanov, and Argonne National Laboratory for their willingness to provide XAS data for my project. My advisor, Michelle Scherer, has taught me a great deal about aquatic geochemistry and the scientific method through the opportunity she provided me to research in the laboratory. She has also provided invaluable guidance in solving problems, maintaining focus, and making sense of data. If anyone is capable of gleaning information out of this thesis, it is due to her ability to present information in an approachable manner. The research assistants in Michelle's group helped me through countless struggles. I doubt I would even know how to pipette correctly without their guidance. I would like to thank Rob Handler, especially, for providing me with the basic knowledge and tools to pursue scientific inquiries. He was always willing to help, even in the midst of writing his own dissertation. Lastly, I thank my friends and family for helping me keep things in perspective and providing love and support. The journey hasn't always been easy, but it has been very rewarding. v ABSTRACT Iron is ubiquitous in the environment, ranking fourth in abundance in the earth's crust. Iron is responsible for many environmental mechanisms including the distribution of plant nutrients and pollutants. Iron can exist in several minerals, including iron oxides. Arsenic is a naturally occurring metalloid which has been confirmed by the EPA as a carcinogen. Recently, an arsenic epidemic has developed in Bangladesh, poisoning an estimated 70 million people. Arsenic contamination does not exist only in the third world, but also in the United States, including Iowa. Due to the widespread distribution of arsenic and the potential for it to be leached into groundwater supplies, there has been a growing interest in establishing removal mechanisms. Atomic absorption (AA) spectroscopy and inductively coupled plasma optical emission spectrometry (ICP-OES) have been the traditional methods to measure arsenic. There has been a shift in arsenic analysis methods with the advent of more …