Wednesday, April 2, 2008 : 9:20 a.m.

The Efficacy of Bacteroides as a Fecal Tracer in Shallow Groundwater

Peter Knappett, MASc, Larry D. McKay, Ph.D. and Alice Layton, PhD, University of Tennessee

Bacteroides has the potential to be a highly efficient fecal indicator bacterium in hydrologic settings.  It has been demonstrated as a molecular fecal source tracking tool in a variety of surface water environments (Layton et al., 2006).  In groundwater, it may be particularly useful, due to its very high concentration in fecal material, as well as its general absence in the environment outside of the intestines of warm blooded animals.  A critical question before Bacteroides may be applied to groundwater settings is: is the transport of Bacteroides similar to traditional fecal indicator bacteria and pathogens?  To answer this question, both column and field injection experiments will be conducted, where a dilute fecal slurry is injected and breakthrough curves measured for Bacteroides, fecal indicators, microspheres and pathogens.  Expected important parameters determining the degree of similarity in transport amongst bacteria are grain size and fecal slurry aggregate size. 

Observations from column experiments, elucidating basic mechanisms of removal, will be linked to a field site in Bangladesh where high resolution geological and epidemiological data has been collected over the last 20 years.  Broad targeted groundwater sampling as well as a detailed flow path (source to well) will be completed to determine the distribution and origin of fecal contamination throughout the field site.  A specific goal is to determine whether a correlation between the spatial/temporal distribution of fecal bacteria and the surficial geology and recharge rates exists.  The planned field-scale transport studies will substantially increase the knowledge base on in situ microbial transport.

Peter Knappett, MASc, University of Tennessee Graduated from the University of Waterloo BSc in 2001. Did research on a DAAD scholarship on waterborne pathogens from 2001-2002 at the UFZ in Leipzig, Germany under Mario and Kristin Schirmer. Worked for Connestoga-Rovers and Associates in Waterloo, Ontario doing groundwater consulting for one year. Graduated from the University of Waterloo MASc in Civil Engineering in 2005 under Prof Monica Emelko. In 2006 I started PhD in microbial transport in groundwater at the University of Tennessee under Prof Larry D. Mckay and Alice Layton.

Larry D. McKay, Ph.D., University of Tennessee Dr. McKay is the Jones Professor of Hydrogeology at the University of Tennessee. His principal research interests are fate and transport of contaminants and tracers in hydrologic systems. He has extensive experience in transport in fractured clay-rich residuum and tills. Dr. McKay is also the GSA Hydro Division's 2008 Birdsall-Dreiss Distinguished Lecturer.


2008 Ground Water Summit