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Efficacy of Bacteroides Measurements for Reducing the Statistical Uncertainty Associated with Hydrologic Flow and Fecal Loads in a Mixed Use Watershed
Author(s) -
Gentry Randall W.,
Layton Alice C.,
McKay Larry D.,
McCarthy John F.,
Williams Dan E.,
Koirala Shesh R.,
Sayler Gary S.
Publication year - 2007
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2006.0496
Subject(s) - baseflow , fecal coliform , watershed , hydrology (agriculture) , environmental science , surface runoff , feces , water quality , streamflow , ecology , drainage basin , biology , geography , geology , cartography , geotechnical engineering , machine learning , computer science
This paper presents an analysis of the occurrence and uncertainty of source‐specific Bacteroides and Escherichia coli in a stream in a mixed land‐use watershed with human, cattle, and wildlife fecal inputs located in a karstic geologic region during baseflow conditions. The objectives of the study were to evaluate the occurrence, hydrologic significance, and source of fecal mass in the stream using assays for total Bacteroides (AllBac) and bovine‐specific Bacteroides (BoBac), and then to compare these measurements with E. coli densities and loads. Samples were collected during baseflow conditions over several months at seven different main channel sites in the Stock Creek watershed, a 49.3 km 2 basin located in Knoxville, TN (USA). We determined instantaneous loads for total fecal loads, bovine fecal loads, and E. coli from measured flow rates and the representative Bacteroides fecal masses and/or E. coli densities. The study indicated a strong correlation between total fecal load (kg d −1 ), bovine fecal load (kg d −1 ), E. coli load rate (CFU d −1 ), 7‐d antecedent precipitation, and turbidity. The various datasets were used to establish parameter correlations and spatial dependencies throughout the watershed. The data analysis demonstrated two prevalent patterns throughout the watershed: (i) a runoff‐dominated transport and occurrence; and (ii) potential groundwater‐dominated transport and occurrence.