CAREER: Assessing the Reactivity and Diversity of Neutrophilic Iron-Oxidizing Bacteria in Terrestrial Aquatic Environments

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Despite their ubiquity and high visibility, rust colored iron oxide deposits remain a poorly understood feature of rivers, lakes, and springs. Until recently, it was assumed that these deposits were formed by abiotic chemical processes; however, recent studies have shown that these deposits often result from the action of specific iron oxidizing bacteria. These bacterial iron oxides may have very different properties than those abiotic oxides that are traditionally used by geochemists in laboratory experiments designed to probe environmental and geochemical reactivity. The overall goal of the project is to characterize the structure, reactivity, and biological diversity of these iron oxide deposits to better understand the multifaceted roles they may play in the environment. To achieve these goals, we will conduct a suite of field, laboratory, microbiological, and spectroscopic analyses aimed at determining key properties of both the iron oxides and the bacteria associated with their formation.Results from this project will advance the fundamental understanding of the behavior of iron in aquatic environments. Because iron oxides are effective sorbents of common nutrients and contaminants, results may also provide new insights into how natural iron oxides affect the mobility and distribution of dissolved species in the environment. The project also incorporates an integrated education and outreach component designed to engage students, teachers, and the general public. In the process of collecting data, we will engage a group of high school teachers and students by conducting presentations at their schools and leading field trips to sample local iron oxide deposits. This activity will be reinforced by summer research visits to the PI's laboratory by participating high school teachers, who will conduct experiments that utilize the same field samples they helped to collect. An additional product of this project will be a map-based web resource that will present field data to help students, teachers, and other citizens understand the importance of biogeochemical processes in their local environment. These activities will help to expand awareness of the importance of geochemistry and geobiology to students and the public, and help to stimulate their curiosity about the science behind natural processes that are occurring in the world around them.