Tab A - Page 45 
to be slow, allowing considerable horizontal movement In even modest winds 
(Vennette and Kennedy, 1975). Ralnsplash has been considered a primary 
mechanism of generating aerosols containing bacteria, but more recent research 
Indicates that high numbers of Ice nucleatlon-actlve strains of s^. syrlnqae 
can enter the atmosphere from dry plant surfaces (llndemann et al. 1979, 1981) 
as well as from ralnsplash (Sands, 1981). (T) 
Long distance transport of Ice-nucleatlon-actlve bacteria through the 
atmosphere appears possible. Ice-nucleation-actlve bacteria have an extensive 
worldwide distribution on plants and these bacteria have been detected in the 
atmosphere In diverse parts of the globe removed from plant sources of these 
bacteria (Flanagen and Jayaweera, 1980; Savena, 1981). Indeed, the ubiquity of 
these species may be due in part to such long distance transport. Many 
bacteria have been shown to be sensitive to desiccation and ultraviolet light 
whiie suspended in aerosols (Gregory, 1973) and have only a limited life 
expectancy while In the air. Should this also be the case for Ice- 
nucleation-active bacterial species. It would be advantageous If they could be 
removed from the atmosphere and deposited on plant surfaces that probably 
provide a more hospitable environment for growth and survival. As small 
aerosol particles, bacteria would not sediment rapidly from the upper 
atmosphere, but could be removed rapidly in precipitation. (T) 
The presence of Ice nuclei In the atmosphere Is important in precipitation 
processes. Much water in the atmosphere exists as small droplets of 
supercooled water or as water vapor In equilibrium with this supercooled water 
(81 gg , 1953). Significant deposition of these water droplets occurs only when 
they Increase In size, increasing their rate of settling (Hobbs, 1974). One 
42 
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