Microbial Influences on Karst Dissolution: The Geochemical Perspective, with a Chapter on Assessment of the Spreadsheets Across the Curriculum Project

Microbes are prevalent in geologic settings and a growing body of research suggests the roles they play in geologic processes may be more important than previously thought, and therefore underestimated. This dissertation addresses the influence of microbes on the dissolution of limestone in karst settings by analyzing the stable carbon isotopes and geochemistry of air and waters from three unique cave and karst settings: West-Central Florida, the Everglades (southern Florida) and The Bahamas. In Florida, these parameters as well as air/water temperature, rainfall, and water-level fluctuations were monitored for 22 and 10 months. In the Bahamas, geochemical data were collected from at varying time-intervals from a variety of cave and surface water bodies. Results showed that microbial respiration in these environments is an important source of carbon dioxide, which contributes to the formation of carbonic acid, which appears to be the major dissolving agent at each of these sites. At the same time, microbially-mediated oxidation of both organic matter and minerals exerts a secondary dissolution control by providing additional acid and inorganic ions that dissolve rock and/or inhibit limestone precipitation. This dissertation also includes a chapter discussing the role of the USF Department Geology in the evolution of assessment for Spreadsheets Across the Curriculum (SSAC) project, which promotes quantitative literacy (QL) by teaching math in the context of other disciplines. Assessment occurred primarily in the Computational Geology course from 2005 to 2008 and showed that this teaching strategy fostered gains in math knowledge and positive math association. Simultaneously, instructors xiv learned that pre-planning and adaptability was central to developing a successful assessment strategy, which, when combined with the heterogeneity of subjects each year, presents challenges in the yearly comparison of results. These conditions are common in educational settings, illustrating the impracticality of standardized assessment instruments and practices, and the importance of the extensive preparation required in identifying assessment goals and the best strategies for achieving them in a given setting