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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 #317069
Title: Spatial and temporal variation of fecal indicator organisms in two creeks in Beltsville, Maryland

Author
item STOCKER, MATT - Orise Fellow
item RODRIGUEZ-VALENTIN, JOSE - University Of Puerto Rico
item Pachepsky, Yakov
item Shelton, Daniel

Submitted to: BARC Poster Day
Publication Type: Abstract Only
Publication Acceptance Date: 5/7/2015
Publication Date: 5/20/2015
Citation: Stocker, M., Rodriguez-Valentin, J., Pachepsky, Y.A., Shelton, D.R. 2015. Spatial and temporal variation of fecal indicator organisms in two creeks in Beltsville, Maryland. BARC Poster Day. 26th Annual Beltsville Poster Day, National Agriculture Library on May 20, 2015.

Interpretive Summary:

Technical Abstract: Evaluation of microbial water quality is commonly achieved by monitoring populations of indicator bacteria such as E. coli and enterococci. Monitoring data are utilized by water managers to predict potential fecal contaminations well as a decision tool to improve microbial water quality. Both temporal and spatial variability of fecal indicator concentrations have been observed. For example, the occurrence of elevated levels of indicators in watersheds after storm events, due to runoff induced suspension of sediments, has been well documented. However, much less is known about variability under base flow conditions. The objective of this study was to quantify the variability of E. coli and enterococci in two small streams running through agricultural land use areas. Water at locations upstream and downstream relative to agricultural land was grab-sampled every second or third day for a month; samples were taken three times a day at three positions across the stream. Differences in E. coli and enterococci concentrations were not significantly different across the streams. Diurnal trends were observed at each of the sampling locations, although differences were not consistently statistically significant. . Statistically significant differences in concentrations along reaches were noted for both creeks during the base flow periods; i.e. no runoff. A hypothetical explanation is that indicator organisms were released from sediment due to the effect of groundwater influx into streams. Since the release of fecal indicator organisms from bottom sediments to the water column is currently thought to result from runoff induced suspension of sediment the possibility that organism release may also be mediated by ground water intrusion may affect our understanding and prediction of the role of bottom sediments in microbial quality of surface waters.