BEG Seminar
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Start: |
March 5, 2015 at 10:30 am |
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End: |
March 5, 2015 at 11:30 am |
| | Location: | BEG Main Conference Room; Building 130; PRC Campus |
| | Contact: | Sophia Ortiz, sophia.ortiz@beg.utexas.edu, 512.475.9588 |
| | URL: | Event Link |
William W. Simpkins
Professor and Chair, Department of Geological and Atmospheric Sciences
Smith Family Foundation Departmental Chair in Geology
Iowa State University
Abstract:
Enteric viruses have been observed in the Ames aquifer, an alluvial/buried valley aquifer composed of sand and gravel that supplies drinking water to Ames, Iowa (pop. 59,000). The focus of this study was the Downtown well field, where continuous pumping induces flow from the South Skunk River (SSR) nearly 1.4 km away into the well field. Because the SSR watershed contains 13 wastewater treatment plants and 109 swine CAFOs upstream, it was hypothesized that enteric viruses of both human and animal origin could be drawn into the well field by induced infiltration. The experimental design consisted of four sampling sites along a groundwater flow path at distances of 3.1 m to 2 km from the SSR. Velocity estimates predict that viruses would travel to Site D at the farthest point within two years. Fifty samples were collected and analyzed for adenovirus, enterovirus, norovirus, rotavirus, Bacteroides, and Hepatitis E virus (HEV), as well as Cl, ?18O, and ?2H, during seven sampling events (October 2011 to October 2012). Untreated sewage was sampled twice. Viruses were analyzed using real-time qPCR and RT-qPCR methods. At least one virus was detected in 42% of the samples, with groundwater showing detections in 39% of samples in the unconfined part of the aquifer next to the SSR and in 28% of the samples in the confined part of the aquifer. Adenovirus Subgroup A and HEV were the most frequently detected. Sewage samples showed the highest concentrations of adenovirus subgroups A and C, D, F, but contained no HEV. Sequencing showed adenovirus A31 to be the only serotype in the SSR and sewage; G3 HEV was the only genotype present and only in the SSR. This evidence suggests that the SSR is the source of G3 HEV (likely a swine source) and adenovirus A31 (human source) in the aquifer, thus confirming the original hypothesis about groundwater transport via induced infiltration. The occurrence of G1 norovirus and Campylobacter jejuni in two municipal wells, but not in the SSR, suggests possible entry through leaks in the sanitary sewer systems and/or well casing. In the case of enteric viruses in the Downtown well field, human enteric viruses come both river and sanitary sewer sources, while animal enteric viruses appear to come solely from the South Skunk River.
