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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 #418812
Research Project: Improving Pre-harvest Produce Safety through Reduction of Pathogen Levels in Agricultural Environments and Development and Validation of Farm-Scale Microbial Quality Model for Irrigation Water Sources

Location: Environmental Microbial & Food Safety Laboratory

Title: Spatiotemporal trends of E. coli levels and their influences vary among ponds in the coastal plain of Georgia, USA

Author
item WIDMER, JAMES - University Of Georgia
item Stocker, Matthew
item Strickland, Timothy
item Coffin, Alisa
item Pisani, Oliva
item Sharma, Manan
item Pachepsky, Yakov
item DUNN, LAUREL - University Of Georgia

Submitted to: Journal of Environmental Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/18/2025
Publication Date: 3/31/2025
Citation: Widmer, J.A., Stocker, M.D., Strickland, T.C., Coffin, A.W., Pisani, O., Sharma, M., Pachepsky, Y.A., Dunn, L.L. 2025. Spatiotemporal trends of E. coli levels and their influences vary among ponds in the coastal plain of Georgia, USA. Journal of Environmental Quality. https://doi.org/10.1002/jeq2.70018.
DOI: https://doi.org/10.1002/jeq2.70018

Interpretive Summary: Quantification of E. coli in water is commonly used to understand a surface source’s suitability for irrigation of produce fields. Sampling and enumeration of E. coli is much more time- and resource-demanding than sensing physicochemical properties of water with electrodes. We aimed to determine if sensing physicochemical properties can guide sampling for E. coli. We used data from three years of biweekly spatially dense sensing and sampling of three irrigation ponds in Georgia and found that the stable patterns of physicochemical properties and E. coli concentrations exhibit persistent spatial patterns. These patterns appeared to be correlated, and therefore, establishing patterns of sensed physicochemical properties could indeed suggest where to sample to more reliably characterize the distribution of E. coli across the pond. The results of this work may be of use to irrigation water quality professionals in that they suggest a way of improving the design of microbiological water quality surveys and monitoring for irrigation ponds

Technical Abstract: Quantification of Escherichia coli in water is commonly used to understand a surface source’s suitability for produce irrigation. However, factors like geographic location, season, and physicochemical water quality can impact the levels of E. coli in irrigation ponds. To determine the extent of this impact, water samples were collected periodically along a sampling grid and enumerated for E. coli along with collection of relevant physical and chemical parameters. Mean relative difference (MRD) was calculated for each collection point to highlight differences in E. coli levels across different pond areas. E. coli levels varied significantly by sampling location and type (perimeter, surface, subsurface) at all three ponds. The Sumner Pond had MRD values ranging from -0.25 to 0.33, the Ty Ty South Pond had MRD values ranging from -1.5 to 0.75, and the Ty Ty North Pond had MRD values ranging from -1.25 to 0.65. At Ty Ty South, E. coli level correlated negatively with dissolved oxygen (DO), and positively with pH. At Sumner, E. coli MRD correlated positively with chlorophyll, and turbidity, and negatively with dissolved organic matter, DO, specific conductance, and pH MRDs. At Ty Ty South, the MRD of E. coli correlated with the MRDs of chlorophyll, DO, phycocyanin, pH, and temperature. At Ty Ty North, E. coli MRD correlated positively with nitrate MRD. MRD may reveal stable patterns of E. coli and the physicochemical factors that can impact these levels in ponds, but no universal drivers were identified that could be reliably used for estimation of E. coli levels