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This article in JEQ

  1. Vol. 36 No. 3, p. 718-729
     
    Received: June 27, 2006


    * Corresponding author(s): jrvogel@usgs.gov
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doi:10.2134/jeq2006.0246

Identifying Fecal Sources in a Selected Catchment Reach Using Multiple Source-Tracking Tools

  1. Jason R. Vogel *a,
  2. Donald M. Stoeckelb,
  3. Regina Lamendellac,
  4. Ronald B. Zelta,
  5. Jorge W. Santo Domingod,
  6. Steven R. Walkere and
  7. Daniel B. Oertherc
  1. a USGS, 5231 S. 19th St., Lincoln, NE 68512
    b USGS, 6480 Doubletree Ave., Columbus, OH 43229
    c Dep. of Environmental Engineering, Univ. of Cincinnati, Cincinnati, OH 45220
    d USEPA Office of Research and Development, National Risk Management Research Lab., 26 Martin Luther King Dr., MS-387, Cincinnati, OH 45268
    e Nebraska Dep. of Environmental Quality, 1200 “N” St., Suite 400, P.O. Box 98922, Lincoln, NE 68509

Abstract

Given known limitations of current microbial source-tracking (MST) tools, emphasis on small, simple study areas may enhance interpretations of fecal contamination sources in streams. In this study, three MST tools—Escherichia coli repetitive element polymerase chain reaction (rep-PCR), coliphage typing, and Bacteroidales 16S rDNA host-associated markers—were evaluated in a selected reach of Plum Creek in south-central Nebraska. Water-quality samples were collected from six sites. One reach was selected for MST evaluation based on observed patterns of E. coli contamination. Despite high E. coli concentrations, coliphages were detected only once among water samples, precluding their use as a MST tool in this setting. Rep-PCR classification of E. coli isolates from both water and sediment samples supported the hypothesis that cattle and wildlife were dominant sources of fecal contamination, with minor contributions by horses and humans. Conversely, neither ruminant nor human sources were detected by Bacteroidales markers in most water samples. In bed sediment, ruminant- and human-associated Bacteroidales markers were detected throughout the interval from 0 to 0.3 m, with detections independent of E. coli concentrations in the sediment. Although results by E. coli-based and Bacteroidales-based MST methods led to similar interpretations, detection of Bacteroidales markers in sediment more commonly than in water indicates that different tools to track fecal contamination (in this case, tools based on Bacteroidales DNA and E. coli isolates) may have varying relevance to the more specific goal of tracking the sources of E. coli in watersheds. This is the first report of simultaneous, toolbox approach application of a library-based and marker-based MST analyses to flowing surface water.

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