Resuspension of sediment-associated Escherichia coli in a natural stream.
In this study, a tracer bacteria was used to investigate the resuspension and persistence of sediment-associated bacteria in a small alluvial stream. The study was conducted in Swan Creek, located within the Grand River watershed of Ontario, Canada. A 1.1-m2 section of the bed was seeded with a strain of Escherichia coli resistant to nalidixic acid (E. coli NAR). The survival, transport, and redistribution of the tracer bacteria within a 1.7-km river section downstream of the source cell was assessed for a 2-mo period following the introduction of the tracer bacteria. This study has illustrated that enteric bacteria can survive in bed sediments for up 6 wk and that inactivation of the tracer bacteria resembled typical first-order decay. Critical conditions for resuspension, as well as resuspension rates, of sediment-associated bacteria were determined for several storm events. The critical shear stress for E. coli NAR resuspension in Swan Creek ranged from 1.5 to 1.7 N m(-2), which is comparable with literature values for critical shear stresses for erosion of cohesive sediments. Bacteria resuspension was primarily limited to the rising limb of storm hydrographs implying that a finite supply of sediment-associated bacteria are available for resuspension during individual storm events. The information presented in this paper will further the development of representative microbial water quality models.
Jamieson
Rob C
RC
School of Engineering, University of Guelph, Ontario, Canada. jamiesor@uoguelph.ca
Joy
Douglas M
DM
Lee
H
H
Kostaschuk
R
R
Gordon
Robert J
RJ
D004926:Escherichia coli; D019015:Geologic Sediments / Q000382:microbiology*; D011157:Population Dynamics; D011891:Rain; D045483:Rivers; D013534:Survival; D014872:Water Movements