Abstract
In order to study the behaviour of pathogenic viruses in groundwater, several tracer experiments were performed at chalk aquifer sites using three different bacteriophage. Laboratory experiments were performed in parallel to investigate the efficacy of the bacteriophage as models of pathogenic virus behaviour. The high titres per ml of bacteriophage available for the initial inoculum and the simplicity of the assay permitted the detection of a pattern of bacteriophage recovery from three different groundwater sites. The greatest percentage of original inoculum recovered was 1.9 percent. Bacteriophage were observed to migrate 1km over a five month period and 366m within just over 3.5 hours. The laboratory experiments explored: i) decay rates of viruses suspended within chalk groundwater; ii) adsorption of viruses to chalk in batch studies and; iii) virus behaviour in chalk columns representing natural aquifer conditions. Three human enteric viruses were used: poliovirus 1, echovirus 1 and coxsackievirus B5. In addition the simian rotavirus (SA-11), and a group of bacteriophage were tested. The laboratory experiments indicated that the bacteriophage included in this study survived longer than the animal viruses in groundwater and that all viruses adsorbed well to chalk. In the simulated aquifer conditions all viruses investigated percolated through a chalk column at a similar rate and with a similar pattern. No differences in behaviour between the viruses, whether in laboratory or field experiments, was found which could be directly attributed to their size or shape. A mathematical model was used which included coefficients for adsorption and decay observed in the laboratory experiments and certain other parameters found in one of the field sites under investigation. Those factors considered and included in the model were shown to be sufficient to produce the same behaviour pattern as that observed in the field. This confirmed that the main factors influencing viral migration in natural conditions have been considered in this investigation. Bacteriophage were found to be good tracers for determining certain properties of chalk aquifers and a potential model of the behaviour of human enteric viruses in groundwater.