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Differential Decay of Bacterial and Viral Fecal Indicators in Common Human Pollution Sources
Citation:
Wanjugi, P., Mano Sivaganesan, C. Kelty, A. Korajkic, B. McMinn, R. Ulrich, V. Harwood, AND O. Shanks. Differential Decay of Bacterial and Viral Fecal Indicators in Common Human Pollution Sources. Presented at 2016 Recreational Waters Conference, New Orleans, LA, April 12 - 15, 2016.
Impact/Purpose:
To inform the public.
Description:
Understanding the decomposition of different human fecal pollution sources is necessary for proper implementation of many water quality management practices, as well as predicting associated public health risks. Here, the decay of select cultivated and molecular indicators of fecal pollution originating from fresh human fecal, septage, and untreated sewage in a subtropical marine environment was assessed over a six day period with an emphasis on the influence of ambient sunlight and indigenous microbiota. Ambient water mixed with each fecal source (1:10 dilution) was placed in dialysis bags and incubated in situ in a submersible aquatic mesocosm. Genetic and cultivated fecal indicators including fecal indicator bacteria (enterococci, E. coli, and Bacteroidales), coliphage (somatic and F+), and human-associated genetic indicators (HF183/BacR287 and HumM2) were measured in each sample. Simple linear regression assessing treatment trends in each fecal type over time showed significant decay trends (p ≤ 0.05) in most treatments in fecal and sewage sources (27/28 and 32/40, respectively), compared to septage source (6/26). A two-way ANOVA comparison of log10 reduction values for sewage and fecal experiments indicated that treatment effects differentially impact survival of cultivated bacteria, cultivated coliphage, and genetic indicators. Findings suggest that sunlight is critical for coliphage decay, while indigenous microbiota plays a greater role in decay of genetic indicators in sewage compared to fecal source. This study offers new insights on the decay of common human fecal pollution sources in a subtropical marine waters with important implications for future water quality management applications.