Viruses and Bacteria in Karst and Fractured Rock Aquifers in East Tennessee, USA

Abstract

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%).

Sustained Anthropogenic Impact in Carter Saltpeter Cave, Carter County, Tennessee and the Potential Effects on Manganese Cycling

“…Field tests (pH, conductivity, etc.) revealed values for CSPC that were consistent with those reported from other caves and local springs contaminated with fecal indicators (Johnson et al, 2011;Simon and Buikema, 1997). Elevations in septicassociated chemicals including chloride, fluoride, and phosphate strongly suggest the presence of septic input from 2010 to 2011 (Fig.…”

“…represents a prominent new alternative indicator for the detection of fecal pollution in environmental samples due to an inability to survive in a non-host environment for lengthy periods of time, a strict association with warmblooded animals, and a relative abundance of members of this genus in fecal samples as compared to traditional indicators (Ahmed et al, 2008a). Molecular-based methods have also been successfully employed in other studies to detect the presence of human fecal indicators in karst aquifers (Johnson et al, 2011;Reischer et al, 2007) and human impact in caves (Johnston et al, 2012).…”

“…As a result, indirect methods of water monitoring for microbial contaminants are frequently employed by researchers: culture-based studies of water to detect coliform bacteria (Mikell et al, 1996;Rusterholtz and Mallory, 1994), molecular techniques to identify the presence/absence of fecal indicators and endemic species in karst systems (Ahmed et al, 2008;Johnson et al, 2011;Johnston et al, 2012;Porter, 2007;Roslev and Bukh, 2011), and the use of fluorescent dyetracers and microspheres to model water flow and pathogen dispersal in conduit systems (Goeppert and Goldscheider, 2011). Direct study of karst environments is restricted to open conduits that are large enough to allow for human movement and environmental manipulation.…”

EPA Method 1615. Measurement of Enterovirus and Norovirus Occurrence in Water by Culture and RT-qPCR. I. Collection of Virus Samples

“…Most of the facilities using groundwater in these studies obtained water from aquifers located in karst regions. These, along with those located in limestone and crystalline (fractured bedrock) settings are likely to have higher virus concentrations than in other settings 8,15,16 . USEPA virus methods specify sampling volumes of 200 L (ICR) to 300 L (Method 1615) of surface water and 1,000 L (ICR) to 1,500 L (Method 1615) of groundwater 17,18 .…”

Characteristics of Point Recharge in Karst Aquifers

“…Because of their high yields, carbonate aquifers are commonly used for community and non-community water supplies [8]. For example, 25% of drinking water supplies are sourced from a geological setting covering approximately 10% of the earth's land surface [9][10][11], and comprise some 40% of the groundwater of the United States [12].…”