Visiting Speaker - Dr. Danielle Fortin

The Department of Geological Sciences and Geological Engineering Visiting Speaker Series Presents:

Dr. Danielle Fortin, University of Ottawa

Talk Title: Chemical, mineralogical and sorptive characteristics of Biogenic Iron Oxides (BIOS)

Date: Thursday, October 5

Time: 12:30 pm - 1:30 pm 

Location: Miller Hall, Room 201

Coffee and treats will be served.

Abstract: 

Biogenic iron oxides (BIOS) form when Fe(II)-rich anoxic waters encounter sub-oxic conditions which are ideal conditions for neutrophilic iron oxidizing bacteria. The end result of their metabolic activity is the formation of occasionally large accumulations of poorly ordered iron oxides mixed with bacterial exopolysaccharides (in the form of sheaths and stalks). X-ray diffraction analysis indicates that BIOS are mainly composed of poorly ordered ferrihydrite but small amounts of lepidocrocite and goethite are also present. BIOS present in pH-neutral mining-impacted areas have been shown to immobilize large quantities of toxic metals, including Pb and Zn and metalloids, such as As. Microbial reduction experiments have revealed that the sorbed contaminants are however released back into solution, along with Fe(II) when BIOS undergo reductive dissolution. In addition, iron-rich biofilms collected from acid mine and acid rock drainage areas were analyzed for their rare earth element content (REEs content). Results indicate that REE sequestration is strongly pH dependent. Lower pH values are associated with greater aqueous REE concentrations whereas, higher pH values are associated with greater biofilm REE concentrations. The total REE content of dried biofilms was two to five orders of magnitude higher than the REE content of co-existing waters. Ongoing experiments are investigating the organic carbon content of BIOS on metal sorption and the role of sorbed impurities (such as Si and PO4) on their microbial reduction. In summary, natural BIOS play a key role in various contaminants’ fate and have the potential to be used to clean-up contaminated areas as long as oxic conditions are maintained within BIOS in order to prevent reduction and contaminant release.

Bio:

Professor Fortin is known internationally for her work on iron geomicrobiology. She established one of the first geomicrobiology research lab in Canada when she joined the University of Ottawa. Professor Fortin is an elected Fellow of the Geochemical Society and the European Geochemical Association. She is also a frequent panel member of the NASA Exobiology program and the NSF Geobiology program. Professor Fortin has been a pioneer in the field of geomicrobiology, inspiring a new generation of geomicrobiologists worldwide.