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Title: TRANSPORT AND RETENTION OF E. COLI IN SATURATED STRUCTURED SOIL

Author
item GUBER, ANDREY - USDA-ARS,VSTNG SCIENTIST
item Shelton, Daniel
item Pachepsky, Yakov

Submitted to: American Geophysical Union
Publication Type: Abstract Only
Publication Acceptance Date: 9/13/2004
Publication Date: 12/14/2004
Citation: Guber, A.K., Shelton, D.R., Pachepsky, Y.A. 2004. Transport and retention of E. coli in saturated structured soil.[Abstract] American Geophysical Union. p.27.

Interpretive Summary:

Technical Abstract: Manure is a source of several bacterial pathogens that can potentially contribute to surface and ground water contamination. We hypothesized that manure particulates could enhance bacteria survival, could compete for soil adsorption sites, serve as carriers of microorganisms, and, overall, facilitate bacteria transport. Column experiments were conducted with undisturbed Tyler silt loam soil to test this hypothesis. Manure suspensions, containing E. coli and Cl as a tracer, were applied to soil surface and the saturated flow was maintained for 10 days at 9 C. column experiments. Complementary batch experiments were carried out to measure attachment of E. coli to soil in presence of various amounts of manure. Attachment of E. coli to soil was much smaller in presence of manure, and decreased with the increase in manure contents. E. coli and manure transport was similar at low velocity during the whole experiment. At high flow rates, the E. coli transport was similar to the chloride transport until 0.5 volume of the pore solution was replaced with the influent, and was retarded after that. Variability in flow velocity and its effect on E. coli and manure transport were probably caused by different macroporosity in individual columns of the same soil. Bacteria and manure breakthrough curves had much longer tails compared with chloride. Overall, slow manure transport and high concentration in pore solution decreased attachment to soil and increased survival of E. coli. Increase in flow velocity decreased attachment and entrapment of manure and bacteria in pore space.