Experiments on the dispersion of Lycopodium and Podaxis spores in the air
1961; Wiley; Volume: 49; Issue: 4 Linguagem: Inglês
10.1111/j.1744-7348.1961.tb03662.x
ISSN1744-7348
Autores Tópico(s)Indoor Air Quality and Microbial Exposure
ResumoSUMMARY In twelve experiments known quantities of Lycopodium spores (in five with spores of Podaxis ) were liberated into the open air artificially from a point source, under different meteorological conditions, and trapped on ‘Vaseline’‐coated slides, placed horizontally at: 2.5, 5.0, 10.0, 15.0, 20.0, 25.0 and 30.0 m. from the source, along from five to thirteen radii (20° apart in some experiments, and 5° or 10° apart in others). The size of spore had little effect on the relative numbers of Lycopodium and Podaxis spores deposited at different distances (the deposition gradient), but from a cloud containing ten times as many Podaxis as Lycopodium spores over twice as many Lycopodium were deposited per unit area as were Podaxis spores. The rate of deposition is thus approximately proportional to the volume of the individual spore. Estimated percentage recovery, within the sampling area, of Lycopodium spores liberated varied from 5.4% (afternoon in wind of 4.4 m./sec.) to 91.6% (night in wind of 0.8 m./sec). Recovery of Podaxis varied from 0.3 % by day to 1.6% by night. The results of these experiments are examined in the light of the statistical theories of W. Schmidt and O. G. Sutton, which formulate atmospheric diffusion by eddies, and are found to be in closer agreement with the latter. The values of the parameters ‘ m ’ in Sutton's equation agree excellently with his theoretical values, but the values of the parameter ‘ C ’ are more variable.
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