Page 21

Presentation Title: Iron- and Manganese-Depositing Cold-Seeps: Mineral Formation Along A Freshwater To Marine Ecosystem at Soda Bay, Alaska Discipline: Environmental Science: Geomicrobiology School: Oregon Health & Science University Student Level: Ph.D. Presentation Type: Oral Presentation Abstract: Iron & Manganese Depositing Cold-Seeps: Mineral Formation Along A Freshwater To Marine Ecosystem At Soda Bay, Alaska 1,2 1 3 1 3 2 Wendy F. Smythe , Melanie Kadake , Sean McAllister , Richard Davis , Craig Moyer & Bradley Tebo . 1 2 3 OHSU-CMOP, OHSU-IEH, Western Washington University.

Soda Bay is a pristine low-temperature iron and manganese-depositing ecosystem in Southeast Alaska. Groundwater fluids, supersaturated with dissolved minerals, are transported through fissures of a massive limestone deposit. These fluids are discharged from cold-seeps at the surface forming large mounds. X-ray absorption near edge structure (XANES) mapping shows that seeps are dynamic carbonate rich environments where both reduced and oxidized forms of iron and manganese minerals coexist. Inductively coupled plasma (ICP) analysis indicates that seep fluids are enriched in both CO2 and high concentrations of dissolved Fe (> 1mM) and Mn (> 100ÂľM). These reduced metals may provide fuel for metal-oxidizing chemolithoautotrophic microbes. As fluids flow from their sources, CO2 is out gassed, pH rises, and metal oxidation becomes more thermodynamically favorable, increasing the potential for abiotic oxidation and making it more difficult for microbes to compete with chemical reactions for chemical energy. Preliminary evidence from molecular analyses indicates an abundance of metal-oxidizing microbes and the potential for chemolithoautotrophy within microbial communities. Ultra high-resolution scanning electron microscopy (UHR-SEM) shows close microbe-mineral associations and suggests microbial dissolution of carbonate minerals. Our goal is to better understand the diversity of metal oxidizers, their contribution to overall mineral formation, and geochemical controls dictating why Feoxides dominate in the high flow system while Mn-oxides dominate in the low flow system.

Presenter: Wendy F. Smythe Tribe: Haida Primary Email: Biography Wendy Smythe, an Alaskan Native of the Haida Nation, is a PhD candidate at OHSU-CMOP; she is also an NSF Graduate Research Fellow. Her research focuses on bacteriogenic manganese mineral formation in extreme environments. She studies manganese minerals and associated microbial communities from a hot spring in Yellowstone National Park, a submarine volcano at Loihi Seamount, and cold-seeps along Soda Bay River. She is also the Co-I of two NSF funded Geoscience Education Proposals focusing on incorporating traditional ecological knowledge into geoscience education.


2011 National Conference Student Research Abstracts  
2011 National Conference Student Research Abstracts  

A comprehensive list of the student research topics that will be presented at the AISES 2011 National Conference