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Viruses and Bacteria in Karst and Fractured Rock Aquifers in East Tennessee, USA
Citation:
McKay, L. D., T. B. Johnson, A. C. Layton, S. W. Jones, G. C. Johnson, J. CASHDOLLAR, D. R. DAHLING, L. F. VILLEGAS, G. FOUT, D. E. Williams, AND G. Sayler. Viruses and Bacteria in Karst and Fractured Rock Aquifers in East Tennessee, USA. GROUND WATER. National Ground Water Association, Westerville, OH, 49(1):98-1110, (2011).
Impact/Purpose:
Overarching Objectives and Links to Multi-Year Planning This task directly supports the 2003 Drinking Water Research Program Multi-Year Plan's long term goal 2 to "develop new data, innovative tools and improved technologies to support decision making by the Office of Water on the Contaminant Candidate List and other regulatory issues” under GRPA Goal 2 (Clean and Safe Water). The overarching objective is to provide Agency scientists, risk assessors, and regulators as well as to individuals outside of the Agency that work in the field of drinking water quality the methods they need to measure the occurrence of waterborne viral pathogens. The method improvements will facilitate the development of risk-based assessments and tools used by the Agency to set regulations, policies and priorities for protecting human health. Specific Objectives Subtask A: Improving sample collecting, virus concentration and sample preparation · Develop a less expensive alternative to the Virosorb 1 MDS filter. This work supports the UCMR and other monitoring activities (to be completed by 9/08 in support of LTG2) Subtask B: Molecular and Cultural Assays · To improve the reverse transcription step in reverse transcription-polymerase chain reaction (RT-PCR) assays. · Development of an integrated cell culture/RT-PCR assay that can be used for screening environmental samples. · Begin the development of a reporter gene cell culture system. · Use improved cell culture lines to develop assays for nonculturable or poorly growing viruses. · To use current molecular and cultural virus detection methods in a pilot study to quantitate the impact of disinfection on virus viability and occurrence. These projects will support the UCMR and the CCL2 and CCL3 and are expected to be completed by 9/08.
Description:
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 of the sites were in carbonate aquifers and the other was in fractured sandstone. Four sites (three wells and one spring) were considered to be at “low risk” for fecal contamination based upon the absence of fecal indicators in preliminary testing and other factors; four sites were considered to be at “high risk” for fecal contamination. Enteric viruses (enterovirus and reovirus) were detected by cell culture at least once in 86% of the wells or springs, including all but one of the four sites deemed to be at “low risk.” However, viral RNA was not detected in any of the samples by RT-PCR. Conventional indicators of microbial contamination (E. coli and total coliforms) co-occurred with viruses in 7 of the 9 samples that tested positive for culturable viruses. Bacteroides, an alternative fecal indicator, co-occurred in all but one of the samples containing E. coli or total coliforms, as well as one sample in which viruses, but no other bacterial indicators, were present. Occurrence of culturable enteric viruses in east Tennessee karst aquifers appears to be more frequent than previously measured in studies in karst aquifers in Pennsylvania (8%), the Ozark region of Missouri (<1%), or in karst aquifers in several states from a national microbial water quality survey by the USEPA (43%).