EFFECT OF PH ON BACTERIOPHAGE TRANSPORT THROUGH SANDY SOILS

Effects of pH and hydrophobicity on attachment and detachment of PRD-1 and MS-2 in three different sandy soils were investigated in a series of laboratory-column experiments. Concentrations of the lipid-contain ing phage PRD-1 decreased 3-4 orders of magnitude during passage throu gh the 10-1 5-cm-long columns. Attachment of the lipid-containing phag e PRD-1 was insensitive to pH and was apparently controlled by hydroph obic interactions in soil media. The less-hydrophobic phage MS-2 acted conservatively; it was not removed in the columns at pH's 5.7-8.0. Th e sticking efficiency (alpha) in a colloid-filtration model was betwee n 0.1 and 1 for PRD-1, indicating a relatively high removal efficiency . Phage attachment was reversible, but detachment under steady-state c onditions was slow. An increase in pH had a moderate effect on enhanci ng detachment. Still, these soils should continue to release phage to virus-free water for days to weeks following exposure to virus-contain ing water. In sandy soils with a mass-fraction organic carbon as low a s a few hundredths of a percent, pH changes in the range 5.7-8.0 shoul d have little effect on retention of more-hydrophobic virus (e.g., PRD -1), in that retardation will be dominated by hydrophobic effects. Sha rp increases in pH should enhance detachment and transport of virus pr eviously deposited on soil grains. A more hydrophilic virus (e.g., MS- 2) will transport as a conservative tracer in low-carbon sandy soil.