FIELD TESTING AND EVALUATION OF DUST DEPOSITION AND ...

Horizontal flux of PM10 by DustTrak normalized to the FLux at
Tower1
1.5
1.4
1.3
1.2
1.1
1
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
T1 (7 m) T2 (50 m) T3 (100 m)
a. Comparison of horizontal flux among the three downwind towers.
Relative concentration of particles in size range
normalized to mass in 3.9 micron size bin
1.2
1.0
0.8
0.6
0.4
0.2
0.0
Normalized concentration at 100 m (T3) divided by initial value
(T3) of ratio of mass in bin to mass in 3.9 micron size bin
ISC prediction (u* =0.35 m/s)
ADE prediction (u* = 0.35 m/s)
3.9 5.6 7.2 9.9 14 19.7
Particle Diameter (microns)
b. Comparison of particle size distributions at Towers 1 and 3
Figure 5-11. Particle removal rates measured at Ft. Bliss at tower 100 m downwind of an unpaved
road. a. Comparison of horizontal flux among the three downwind towers. Data are averages over 27
individual passes when the wind direction was within 15 degrees of perpendicular to the road.
Concentrations measured with DustTrak monitors with PM 10 inlets. Fluxes calculated according to
Equation 5-1 and normalized to value at Tower 1. Vertical bars indicate standard errors; b.
Comparison of particle size distributions at Towers 1 and 3 measured by GRIMM 1.108 OPC with
model predictions. Data are averages over 137 individual passes. X-axis shows particle aerodynamic
diameter calculated by assuming a density of 2.6 g/cm 3 and geometric mean diameter representing
each size bin. Particle concentrations at Towers 1 and 3 were each normalized by concentration of
3.9 micron particles. Y-axis represents ratios of normalized concentrations.
The finding that there is no measurable removal of PM 10 particles can be further
supported by examining the particle size distributions measured at T1 and T3. Figure
5-11b shows the ratio of particle concentrations measured at the same height (2.66 m) on
both towers. The figure represents data from 137 individual passes. The x-axis shows
the mean geometric diameter for the size bin measured. Aerodynamic diameters have
5-16