Submitted to: Joint Assembly of the European and American Geophysical Unions
Publication Type: Abstract only
Publication Acceptance Date: 1/31/2003
Publication Date: 4/6/2003
Citation: Pachepsky, Y.A., Shelton, D.R., Sadeghi, A.M., Stout, W.L. 2003. Transport of manure-borne bacteria and colloids in a stony soil. Joint Assembly of the European and American Geophysical Unions, April 6-10, 2003, Nice, France. Paper # EGU03-A-03 812. Interpretive Summary:
Technical Abstract: Manure is a source of several microorganisms that can potentially contribute to surface and ground water contamination. As manure dissolves, microorganisms are released along with manure colloids. We hypothesized that transport of manure-borne bacteria in soils can be viewed as the colloid-facilitated transport. To test this hypothesis, we simulated rainfall of 7.1 cm h-1 to the surface of 90 cm-long lysimeters filled with the undisturbed stony soil. Bovine manure mixed from potassium bromide solution was placed on the soil surface, rainfall continued for about five hours after manure application, and effluent collected each 10 min was analyzed for turbidity, bromide-ion, and fecal coliform (FC) content. FC and turbidity had similar breakthrough curves with low dispersion. The convective-dispersive equation with linear adsorption/exclusion and the first-order removal/re-growth terms could be used as a model of the FC transport in soil, whereas the mobile-immobile zone model had to be used for the bromide transport. The average velocity of bacteria and manure colloids was about seven times larger than the average pore water velocity. Porosity available for FC and manure particulate transport was close to the water content in the mobile zone as determined from the bromide breakthrough. The regression line of reduced coliform concentrations on reduced turbidity values was not significantly different from the 'one-to-one' line. Average values for the release rate constants were not significantly different for FC and manure colloids. Data of this work support the hypothesis that transport of manure-borne microorganisms has to be studied and mitigated as a colloid-facilitated transport.