A　quartz　crystal　microbalance　(QCM)　coupled　with　a　radial　stagnation　point　flow　(RSPF)　cell　was　used　to　study　deposition　kinetics　of　bacteriophage　MS2　on　silica　surface　coated　with　Suwannee　River　natural　organic　matter　(SRNOM).　Three　stocks　of　MS2　stored　in　1　mM　NaHCO　3　,　deionized　(DI)　water　or　phosphate　buffer　saline　(PBS)　solution　were　studied.　MS2　stored　in　PBS　solution　were　found　to　aggregate　at　all　studied　ionic　strengths　from　3　mM　to　200　mM,　while　MS2　stored　in　DI　water　and　bicarbonate　solutions　remained　monodispersed.　Isoelectric　points　of　MS2　stored　in　PBS　solution　were　lower　than　for　those　stored　in　DI　water　and　1　mM　NaHCO　3　solution.　Nonrepulsive　deposition　rates　of　MS2　on　silica　surface　coated　with　poly-L-lysine　(PLL)　were　independent　of　ionic　strength.　In　contrast,　MS2　deposition　rates　on　bare　silica　surface　or　silica　surface　coated　with　SRNOM　increased　gradually　and　stabilized　at　an　ionic　strength　of　60　mM.　MS2　deposition　rates　on　bare　silica　surface　were　higher　than　those　on　silica　surface　coated　with　SRNOM　at　low　ionic　strengths.　Deposition　rates　on　these　two　surfaces　were　similar　at　high　ionic　strengths.　Experimental　data　suggest　that　electrostatic　and　steric　interactions　were　the　two　main　deposition　mechanisms　of　MS2　on　either　bare　silica　or　silica　surface　coated　with　SRNOM.　©　2008　American　Chemical　Society.