|Hill, Robert -|
Submitted to: BARC Poster Day
Publication Type: Abstract Only
Publication Acceptance Date: March 16, 2009
Publication Date: April 15, 2009
Citation: Garzio-Hadzick, A.M., Shelton, D.R., Hill, R.L., Guber, A.K., Rowland, R.A., Hadzick, Z.Z., Pachepsky, Y.A. 2009. Survival of E. coli in stream sediment as affected by temperature, texture, and organic matter. BARC Poster Day April 15, 2009. Technical Abstract: Concentrations of E. coli bacteria are mandated by the Environmental Protection Agency (EPA) to evaluate water quality in order to designate impaired creeks and to design management practices to prevent fecal contamination of water. Many of these management practices are designed to prevent runoff from agricultural fields, implying that manure is the source of E. coli when it enters stream water. Recent studies have shown that stream sediment acts as a reservoir and potent source of fecal bacteria. This study was conducted to determine if (a) E. coli survival in the presence of manure material will be affected by either sediment particle size distribution, or sediment organic matter content, or both, and (b) temperature will affect the survival of E. coli in the same way as it affects survival of E. coli in other environmental media. Experiments were carried out at three temperatures –4 ºC, 14 ºC, and 24 ºC - with stream sediment and water from an agricultural stream in USDA-ARS Beltsville, MD, and manure slurry from the USDA-ARS Beltsville dairy farm spiked with E. coli culture. Stream conditions were simulated using innovative flowthrough chambers. The oscillatory growth stage was observed during the first four to seven days at all temperatures before the stage of the exponential inactivation began. The oscillation rhythm did not depend on temperature, but the magnitude did. The E. coli inactivation slowed down as the temperature decreased for the same sediment. The inactivation rates had the classical power law dependence on temperature during the exponential inactivation stage. Both increase in sediment clay content and in organic matter increased the initial growth and slowed the inactivation down. At the lowest temperature, E. coli persisted for three months in sediment and seemed to be able to survive in the stream sediment over winter. Overall, sediment provides a hospitable secondary habitat for manure-borne E.coli with texture, organic matter content and temperature being the inactivation controls.