Novel Time-Integrated Quantification of Sediment-Associated Fecal Indicator Bacteria in Rural Alabama Creek with Straight Pipes

In the Alabama Black Belt, widespread rural poverty, limited sewer access, and shrink-swell clays preclude the use of conventional septic systems, leading to both failing septic systems and discharge of raw sewage from homes through "straight pipes." The degree to which fecal microbes are associated with the suspended sediment load has important implications for contamination transport. Current state guidelines require periodic grab sampling to monitor surface water fecal contamination. While technically simple, grab samples alone are inadequate to monitor enteric pathogens in a body of water due to the highly variable nature of surface water microbes. We present the novel use of the bi-directional time-integrated mass sediment samplers (TIMS) as an accurate and efficient technology for capturing and monitoring fecal indicator organisms and the suspended sediment load. Made of PVC, the TIMS devices are low-cost, easy-to-use, and more effective than grab sampling, especially during periods of high precipitation. While these devices have been utilized for sediment capture in fluvial and estuarine settings, this is the first use of the bi-directional TIMS to characterize sediment-associated fecal microbes. Applied in three locations near known straight pipe usage, the TIMS devices captured significantly more E. coli as compared to grab sampling. This was more pronounced following initial flush precipitation events (i.e. heavy rain after a prolonged dry period) with results yielding an average of 111 times (>2-log10) more E. coli than grab sampling alone. Additionally, the attachment of fecal indicator bacteria to sediment was evaluated using a novel, simple two-step centrifugation-based isolation method. This isolation method was most effective at the 35 °C incubation temperature, which yielded an average of 38.7% sediment-associated E. coli across sampling sites.The results of this study indicate initial flush events are the most critical time to sample surface water for fecal contamination, which paves the way for improved surface water monitoring guidelines and better risk management. These novel methods allow for effective monitoring of the quality of in-situ derived surface water samples over time, providing a deeper understanding of sediment-microbial association and the role precipitation and fine-grained particles have on the fate and transport of fecal pathogens.

Grantor dc:publisher

University of Alabama Libraries

Year dc:date.issued

2024

Author dc:creator

• Baroni, Corinne Maire

Advisor dc:contributor.advisor

• Elliott, Mark

Contributors dc:contributor

• Elliott, Emily
• Terry, Leigh

• Alabama Black Belt
• bi-directional TIMS
• E. coli
• fecal indicator organisms
• sediment-associated bacteria isolation technique
• vertisol clays

Statement dc:rights

• All rights reserved by the author unless otherwise indicated.

Language dc:language.iso

en_US, English

Dc Identifier Other

1086371

OAI identifier oai:identifier

oai:ir.ua.edu:123456789/14412