FIELD TESTING AND EVALUATION OF DUST DEPOSITION AND ...

16
Normalized Deposition Velocity
11
6
1
-4
-9
NX NY PY NZ PX
Direction
Figure 3-4. Directional variation in deposition velocity normal to a flat surface. Data given are mean
and one standard deviation, normalized by the deposition velocity on the horizontal surface facing up
(PZ) averaged for the range 0.5-7.5 m (physical diameter) based on four determinations (SEM 12,
17, 18, 19). The vertical surfaces (NX, NY, PY) show enhanced deposition due to impaction.
Deposition on surface facing down (NZ) and away from the road (PX) is presumed to be due to
turbulence.
100
Normalized Deposition Velocity
10
1
0.1
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
Physical Diameter - microns
NX NY NZ PX PY PZ
Figure 3-5. Directional variation in deposition velocity normal to a flat surface as a function of
particle size. Data are the mean of four determinations (SEM 12, 17, 8, 19), normalized by the
deposition velocity on the horizontal surface facing up (PZ). The plot indicates no consistent size
dependence for particles less than 10 µm in diameter.
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