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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Environmental Microbial & Food Safety Laboratory » Research » Publications at this Location » Publication #350902
Research Project: Design and Implementation of Monitoring and Modeling Methods to Evaluate Microbial Quality of Surface Water Sources Used for Irrigation

Location: Environmental Microbial & Food Safety Laboratory

Title: Spatial patterns of E. coli concentrations in sediment before and after artificial high-flow events in a first-order creek

Author
item STOCKER, MATTHEW - Oak Ridge Institute For Science And Education (ORISE)
item PENROSE, MICHAEL - University Of Texas - El Paso
item Pachepsky, Yakov

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/1/2018
Publication Date: 9/27/2018
Citation: Stocker, M., Penrose, M., Pachepsky, Y.A. 2018. Spatial patterns of E. coli concentrations in sediment before and after artificial high-flow events in a first-order creek. Journal of Environmental Quality. 47(5):958-966.

Interpretive Summary: Microbial water quality is of paramount importance for recreation, irrigation, and other water uses. Fecal indicator bacteria, such as E. coli, are used to determine the potential presence of pathogenic microorganisms in waters. E. coli and other microorganisms can be release to water column during high flow events and indicate the presence of pathogens in water. E. coli populations appear to grow back after the releases but the rate of such growth has net been known so far. We studied the levels of E. coli in sediments along a reach as the creek underwent a series of natural and artificial high-flow events. Depending on sediment properties, both E. coli growth and die-off occurred along the creek during the baseflow between high flow events. Several silty or clay sediment hot spots across the creek reach had relatively high growth rates, and that resulted in the overall growth of the average E. coli concentration across the reach. Results of this work are expected to be used by microbial water quality consultants and agencies in that they provide the first data on sediment E. coli concentrations changes caused by high flow events and regrowth afterwards, indicate the need to relate sediment E. coli monitoring to sediment properties, and imply that the proper representation of the sediment E. coli effect on microbial water quality can be achieved at the reach level rather than locally.

Technical Abstract: Understanding of spatial patterns of E. coli distributions in freshwater sediments is necessary to characterize the storage of sediments as microbial reservoirs and to evaluate the impact of sediment resuspension on microbial water quality in watersheds. Sediment particle size distributions and streambed E. coli concentrations were measured along a 450 m long reach of a first order creek before and after two artificial high-flow events. Variability of E. coli was greater in sediments than in water within any given sampling day, however variation between sampling days was greater for water than for sediment. There was a positive and significant correlation between concentrations of E. coli in water and sediment (rs = 0.70; p = 0.049) at reach scale. Temporally stable patterns of locations within the stream reach were identified where E. coli concentrations were mostly lower, mostly about, or mostly higher than average. E. coli-rich sites along the reach corresponded to areas with higher organic matter and fine particle contents, and low flow stream areas. Although negative growth rates were observed at most sites along the reach during times where no precipitation was recorded, few sites had such large growth that on average the growth rate for all sites remained positive at reach scale. Patterns that we observed contribute to understanding sediment-related modification of microbial water quality.