|Abstract or Summary
- This investigation was initiated in an attempt to delineate
some factors affecting the adsorption of poliovirus to soil particles
in seawater. The results could have significance in the development
of assay procedures for viral contaminants in natural waters.
A sample of marine sediment, obtained from an estuary near
Purdy, Washington, was characterized by X-ray diffraction and
shown to consist primarily of 2:1 type mineralogical components.
When poliovirus type I was mixed with the marine sediment, or
with purified montmorillonite and kaolinite suspensions containing
electrolyte, the virus was removed from the supernatant fluid of
samples subjected to low-speed centrifugation.
Fetal bovine serum, in concentrations of 0.2% to 2%, prevented
and reversed adsorption of the virus to the clay fraction of
the marine sediment. A serum concentration of 0.02% decreased
virus adsorption but 0.002% serum had no effect. Hydrogen ion concentrations, in the range of pH 5 to 9, had no significant effect
on the amount of virus adsorbed by marine sediment suspended in
seawater. Adsorption of virus by the clay fractions of montmorillonite
and kaolinite was more efficient than adsorption by the silt
fractions, although significant removal of virus by the larger particles
did occur. Adsorption of up to 60% of the virus occurred at
clay concentrations as low as 1 mg/liter, while clay concentrations
of 50 mg/liter resulted in almost complete removal of the virus
from the supernatant fluid.
The virus did not adsorb to the clays in a deionized water
medium, but when suspended in seawater diluted to salinities as
low as 0.1%, or in deionized water containing 10⁻⁵M AlCl₃, adsorption
did occur. Clays of the 2:1 type required higher concentrations
of electrolyte than did the 1:1 type kaolinite to adsorb virus. Lower
concentrations of MgCl₂
than NaCl resulted in adsorption. Attempts
to release virus adsorbed to kaolinite, by suspending in a medium of
lower electrolyte concentration, were not successful.
Limited electron microscope studies did not unequivocally
establish the adsorption site of virus to kaolinite crystals, but structural
defects of the crystals were observed which may be important
in the adsorption phenomenon. The mechanism of adsorption has not
been established but a flocculation type is suggested.