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Sediment and fecal indicator bacteria loading in a mixed land use watershed: Contributions from suspended sediment and bedload transport
Citation:
Bradshaw, J., B. Snyder, D. Spidle, R. Sidle, K. Sullivan, AND M. Molina. Sediment and fecal indicator bacteria loading in a mixed land use watershed: Contributions from suspended sediment and bedload transport. JOURNAL OF ENVIRONMENTAL QUALITY. American Society of Agronomy, MADISON, WI, 50(3):598-611, (2021). https://doi.org/10.1002/jeq2.20166
Impact/Purpose:
Transport of FIB increases during rainfall and for extended periods after critical flows for sediment transport are exceeded. In this study, multiyear monitoring and regression relationships between sediment and FIB were used to investigate sediment and FIB-loading.
Description:
Overland transport of fecal bacteria in water and their resuspension from bed sediments are important transport mechanisms that help explain the transport of enteric pathogens in watersheds. In this study, multiyear monitoring along with regression relationships between sediment and fecal indicator bacteria (FIB) were used to investigate annual loading in the South Fork Broad River watershed, located in northeastern Georgia, USA. Suspended transport was the dominant transport mechanism contributing to in-stream total annual loads for sediment (81.4–98.1%) and FIB (>98%). Annual bedload transport of FIB was small and Escherichia coli (up to 1.8%) contributed more to annual bedload FIB than enterococci (≤0.03%). Bedload contributions of FIB increased with the duration of critical discharge exceedance, indicating a prolonged risk of exposure to enteric pathogens during extended periods of high flows, which is important during major storm events. The risk of exposure to enteric pathogens through pathways such as recreational use and drinking water treatment could be much greater because fecal bacteria are released from sediment during higher flows and dominantly transported in suspension when bedload are not actively moving. Therefore, the combined contribution of fecal bacteria from overland and bedload-associated transport should be considered in risk assessments. Discharge, bedload, and FIB data collected over 2 yr in this study can supplement future hydrologic modeling and microbial risk assessment modeling efforts.
URLs/Downloads:
DOI: Sediment and fecal indicator bacteria loading in a mixed land use watershed: Contributions from suspended sediment and bedload transport
PubMed Central Link to Manuscript