Geomicrobiology & Biogeochemical Cycling

Department of Geological Sciences
University of Texas at Austin

 

 

 

 


 

 

 

Geomicrobiology of Silicate Weathering in the Subsurface

Geomicrobiology of Silicate Weathering:

Microorganisms interact with minerals and perturb the geochemical environment. It is through these changes in groundwater chemistry that minerals dissolve and other mineral phases precipitate. There are many unanswered questions about the role microorganisms play in these processes, and since this is a linked system, the problem must be approached from several angles: 1) understanding the microorganisms, 2) knowing the aquifer mineralogy, and 3) determining the composition of aqueous solutions. Our research investigates different aspects of these interactions by specifically targeting mineral weathering, and comparing biotic and abiotic weathering kinetics. Another area of research focuses on microbial nutrition as a mechanism of controlling microbial colonization on silicate surfaces, and consequently enhancing mineral weathering. The role of metabolic byproducts and microbial chelating agents in silicate weathering and iron chemistry are also being investigated.

 

 

 

 

 

 

 

 

 

Geomicrobiology of Sulfidic Karst Systems

Geomicrobiology of Sulfidic Karst Systems:

While most caves and karst features form from carbonic acid dissolution, caves can also form through sulfuric acid dissolution. Sulfuric acid is derived from hydrogen sulfide-rich waters that become oxidized 1) through abiotic reactions from mixing of waters having different concentrations of hydrogen sulfide or mixing reduced and oxygen-rich waters (autoxidation), and 2) from biological reactions. One of the major problems interpreting caves formed by sulfuric acid speleogenesis is recognizing the contribution of microorganisms during cave formation. Therefore, caves presently containing sulfidic waters are being investigated and the wide range of microorganisms thriving in these systems are being characterized through culturing and molecular genetic techniques. Especially of interest are acidophiles living on cave-wall surfaces. Our research focuses on a sulfidic karst system in Wyoming, and links highly interdisciplinary methods to understand the roles of the microbial populations living in the caves