Submitted to: Journal of Environmental Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 9, 2013
Publication Date: April 9, 2013
Citation: Bradbury, K.R., Borchardt, M.A., Gotkowitz, M., Spencer, S.K., Zhu, J. 2013. Time-series analysis of human enteric viruses in municipal water supply wells. Journal of Environmental Science and Technology. 47:4096-4103. Interpretive Summary: Pathogens found in the gastrointestinal systems of humans and animals are released to the environment in fecal material where they can contact and infect a new person or animal. Called the fecal-oral transmission cycle, a key question often asked is what is the source of the pathogens and how did they move to contaminate a new site in the environment where the cycle can begin again? This study showed that by measuring the types and quantities of pathogens at suspected pathogen sources and comparing these measurements to the types and quantities of pathogens at the contaminated site, it was possible to identify the most likely source of pathogens and at the same time estimate the pathogen time of travel. For example, in this study of one urban environment, it was found the types and quantities of pathogens in the wastewater matched the same measurements in the municipal drinking water wells, suggesting that leaking sanitary sewers were the contamination source. Moreover, it appeared the pathogens were moving very quickly from the sewers to the wells, in a time frame of only weeks. The approach developed in this study can be used in other settings to identify fecal contamination sources, for example, manure in agricultural runoff or septic systems. Understanding the movement and fate of pathogens in the environment is helpful for identifying opportunities for interrupting the fecal-oral cycle and preventing disease transmission in people and livestock.
Technical Abstract: Until recently, few water utilities or researchers were aware of possible virus presence in deep aquifers and wells. Over the past several years, repeated detection of enteric viruses in water from deep wells in south-central Wisconsin, shows that viruses can be significant groundwater contaminants and potentially threaten human health. During 2008 and 2009 we collected a time series of virus samples from six deep municipal water-supply wells. The wells range in depth from approximately 200 to 275 m and draw water from a sandstone aquifer. Three of these wells draw water from beneath a regional aquitard, and three draw water from both above and below the aquitard. We also sampled local lakes and untreated sewage as potential virus sources. Viruses were detected up to 61 percent of the time in each well sampled, and many groundwater samples were positive for virus infectivity. Lake samples contained viruses over 75 percent of the time. Sewage samples were all extremely high in viruses. Virus concentrations varied significantly with time, and there was apparent temporal correlation between virus detections in sewage, lakes, and groundwater. Coincidence between viral serotypes found in sewage, lakes, and groundwater suggests very rapid transport, on the order of weeks, from the source(s) to wells. The most likely source of the viruses in the wells is leakage of untreated sewage.