Virus adsorption and inactivation in soil as influenced by autochthonous microorganisms and water content

Virus adsorption and inactivation in soil matrix are crucial processes controlling the potential of viruses to contaminate water resources. These two processes behave interactively and are controlled by various factors. In this study, batch and incubation experiments were conducted at 4 °C to compare the adsorption of bacteriophage MS2 in different soils, and to examine its inactivation behavior at different soil water content. Soils with presence/absence of autochthonous microorganisms were used. The interactive effects of sterilization and soil water content on virus inactivation were also evaluated. The Ustisandic Primosols showed no virus adsorption and minimal differences in activation regardless of the presence or absence of soil autochthonous microorganisms. For the Ferriudic Cambosols, however, sterilization increased adsorption and enhanced inactivation, and inactivation was accentuated by decreasing soil water content. The results indicate that soil water content and sterilization had additive effects on virus inactivation, and reveal that the enhanced “adsorption” by sterilization was mainly due to greater die-off in the Ferriudic Cambosols. The greater inactivation observed in the Ferriudic Cambosols, which has relative high contents of Fe- and Al-oxides and low pH, resulting from the additive effect of sterilization and decreasing soil water content was mainly due to increased reactions at the solid–water interface. We conclude that the effect of sterilization and soil water content on virus inactivation depends on soil type, and the extent of inactivation is likely controlled by the content of metal oxides.