Summary of Studies for

Mira Stone Olson, Fiessinger Scholarship Winner 2002

(Report - summer 2003)

This year has been busy for me.  I am getting closer to completing my Ph.D. experiments and soon hope to move on to analyzing all of my data and writing everything up.  I am studying how chemotaxis affects the transport of bacteria through porous media.  Chemotaxis refers to the ability of bacteria to sense chemical concentration gradients and swim toward regions of optimal contaminant concentration.  Many soil-inhabiting bacterial species capable of transforming pollutants into nontoxic products exhibit chemotaxis toward ground-water contaminants.  I have run several sets of experiments analyzing bacterial transport through packed columns.  I have been studying the effect of an imposed chemical gradient on bacterial transport, and have found that bacteria migrate preferentially to regions containing low concentrations of trichloroethylene (TCE).  I hope to determine if this ability can help bacteria to target less permeable regions in the subsurface where contaminants tend to accumulate. 

I also plan on traveling to Scotland for six weeks this summer to work with researchers at the University of Edinburgh and the Contaminated Land Assessment and Remediation Research Centre.  I will work on a project studying the contribution of aggregates and macrophytes (aquatic plants) on contaminant removal rates in constructed wetlands, and evaluating the effect of varying contaminant loading rates and concentrations on the treatment performance of the wetlands.  My collaborators are constructing twelve experimental wetlands systems, with varying design and operation parameters, to be evaluated for optimal performance. I hope to learn from their knowledge of wetlands design and operation so that I may eventually begin my own study of the effect of plant and bacterial diversity on the contaminant removal rates from aquatic wetlands, perhaps investigating the contribution of chemotactic bacteria.  My recent graduate work has been largely bench-scale, so I am excited for this opportunity to expand from laboratory studies to broader field applications.  I am tremendously grateful to the EREF for allowing me the opportunity to continue with and expand on my research.