Johnson T.B.,Clancy Environmental Consultants LLC |
McKay L.D.,University of Tennessee at Knoxville |
Layton A.C.,University of Tennessee at Knoxville |
Johnson G.C.,U.S. Geological Survey |
And 6 more authors.
Ground Water | Year: 2011
A survey of enteric viruses and indicator bacteria was carried out in eight community water supply sources (four wells and four springs) in East Tennessee. Seven sites derived their water from carbonate aquifers and one from fractured sandstone. Four of the sites were deemed "low-risk" based on prior monitoring of fecal indicators and factors such as presence of thick layers of overlying sediments. The remaining sites were deemed "high-risk." Enteric viruses (enterovirus and reovirus) were detected by cell culture at least once in seven of the eight wells or springs including all but one of the four low-risk sites. Viral RNA, however, was not detected in any of the samples by reverse transcription-polymerase chain reaction. Conventional indicators of microbial contamination (Escherichia coli and total coliform bacteria) were detected together with culturable viruses in seven of nine virus positive samples. Bacteroides, an alternative fecal indicator which has not previously been used in groundwater investigations, was also detected in all but one of the samples containing E. coli or total coliform bacteria, as well as in one sample where viruses were present in the absence of other bacterial indicators. The study highlights some of the challenges involved in surveys of virus occurrence and indicates that culturable enteric viruses in East Tennessee karst aquifers may be more widespread than previously observed in studies of karst aquifers in Pennsylvania (8%), the Ozark region of Missouri (< 1%), or several other states covered in a national microbial water quality survey conducted by the U.S. Environmental Protection Agency (43%). Copyright © 2010 The Author(s). Journal compilation © 2010 National Ground Water Association. Source
Hargy T.M.,Clancy Environmental Consultants LLC |
Rosen J.,Cec Inc. |
Lechevallier M.,Innovation and Environmental Stewardship at American Water |
Friedman M.,Confluence Engineering Group |
Clancy J.L.,Cec Inc.
Journal / American Water Works Association | Year: 2010
To better define the presence of coliform bacteria and Escherichia coli in drinking water distribution systems, a capsule filter sample method was developed for collecting volumes larger than the conventional 100-mL sample. Bench studies indicated this method was capable of consistent detection of the presence of low concentrations of seeded total coliforms and E. coli in 20-L sample volumes. Field trials in distribution systems were performed at three utilities. In 252 sample sets, the 20-L method detected total coliform in 18 samples, but in only two were the corresponding 100-mL samples total coliform-positive. E. coliwas not detected by either sample method at any location. These results indicate that distribution water quality may be better characterized using this high-volume method and suggest that the presence of total coliform positives is a function of sample volume rather than an indicator of water quality. Source