Graduation Year


Document Type




Degree Granting Department


Major Professor

Peter J. Harries, Ph.D.

Co-Major Professor

Jonathan G. Wynn, Ph.D.

Committee Member

Bogdan P. Onac, Ph.D.

Committee Member

Diana E. Northup, Ph.D.

Committee Member

Henry L. Vacher, Ph.D.


karst, dissolution, limestone, microbes, geochemistry


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


(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

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.