Viral transport in a sand and gravel aquifer under field pumping conditions

Ground water supplies contaminated with microbes cause more than 50% of the water-borne disease outbreaks in the United States. Proposed regulations s uggest natural disinfection as a possible mechanism to treat microbe-impact ed ground water under favorable conditions. However, the usefulness of curr ent models employed to predict viral transport and natural attenuation rate s is limited by the absence of field scale calibration data. At a remote fl oodplain aquifer in western Montana, the bacteriophages MS2, Phi X174, and PRD1; attenuated poliovirus type-1 (CHAT strain); and bromide were seeded a s a slug 21.5 m from a well pumping at a steady rate of 408 L/min. Over the 47-hour duration of the test, resulting in the exchange of 12 to 13 pore v olumes, 77% of the bromide, 55% of the PRD1, 17% of the MS2, 7% of the Phi X174, and 0.12% of the poliovirus masses were recovered at the pumping well . Virus transport behavior was controlled by mechanical dispersion, prefere ntial flow, time-dependent nonreversible and reversible attachment, and app arent mass transfer to immobile domains within the sand and gravel dominate d aquifer. The percentage of virus recovery appears correlated with reporte d viral isoelectric point (pI) values. Successful modeling of viral transpo rt in coarse-grained aquifers will require separation of viral specific pro perties from reported lumped viral-transport system parameters.