FIELD TESTING AND EVALUATION OF DUST DEPOSITION AND ...

More documents

Recommendations

Info

Height z (m) 14 12 10 8 6 T2 u*=0.2 T2 u*=0.3 T2 u*=0.4 T2 u*=0.5 T2_ISC_neutral T2_ISC_slightly unstable T2_ISC_moderately unstable T2_ISC_very unstable 4 2 0 0 0.2 0.4 0.6 0.8 1 1.2 Normalized Concentration a. Tower 2 (50 m) Height z (m) 14 12 10 8 6 T3 u*=0.2 T3 u*=0.3 T3 u*=0.4 T3 u*=0.5 T3_ISC_neutral T3_ISC_slightly unstable T3_ISC_moderately unstable T3_ISC_very unstable 4 2 0 0 0.2 0.4 0.6 0.8 1 1.2 Normalized Concentration b. Tower 3 (100 m) Figure 5-9. Normalized measured and modeled gaussian concentration profiles at a. Tower 2, 50 meters downwind of unpaved road and b. Tower 3, 100 meters downwind. unstable conditions. The difference between the ADE and the ISC3 is that in the latter, the dispersion parameter (embodied in σ z ) is allowed to vary with downwind distance, while in the former (embodied in K zz ) the dispersion is only allowed to vary with height. In practical terms, this means that the ISC3 has a correction factor built into it to account for the shortcomings of the ADE close to a source. Figure 5-10 shows the downwind progression of the concentration profiles according to the ADE and the ISC3 model. The results for the ADE are shown for neutral conditions at two values of u * and those for the ISC3 are shown for three stability conditions ranging from neutral to very unstable. At far downwind distances (i.e. > 500 m), the profile for the ADE curve lies between moderately unstable and neutral profiles from the ISC3. This is consistent with the expectation that at further from the source, the assumptions of the ADE are better met than in the immediate vicinity of the source. 5-14
Horizontal fluxes of PM 10 measured at each of the three downwind towers during the 2002 Ft. Bliss experiments appear in Figure 5-11a. The horizontal flux was calculated according to Equation 5-1 using PM 10 concentrations measured with DustTraks at multiple heights on each of the downwind towers. For each pass, the horizontal flux measured at each tower was normalized by the average flux for the three towers. Because of the great variability among fluxes for individual vehicle passes, the columns in the figure represent averages of the normalized flux over 27 passes when the wind direction was known to be within 15 degrees of the vector perpendicular to the road. The vertical bars are standard errors. Figure 5-11a indicates that there is no measurable reduction in PM 10 horizontal fluxes for at least 100 meters downwind of the unpaved road. The fluxes measured at T1 and T2 (50 m) are nearly identical, while those measured at T3 (100 m) are slightly higher, but within two standard errors of T1. This indicates that there is no statistically significant difference (α=0.05) between the horizontal fluxes measured at any of the three towers and that for the conditions at Ft. Bliss, the removal of PM 10 particles over a distance of 100 m downwind of the road is negligible. 250 200 ISC3_neutral ISC3_moderately_unstable ISC3_Very_unstable ADE_u*=0.3 ADE_u*=0.3 250 200 ISC3_neutral ISC3_moderately_unstable ISC3_Very_unstable ADE_u*=0.3 ADE_u*=0.3 hieght z (m) 150 100 hieght z (m) 150 100 50 50 0 0 0.0 0.2 0.4 0.6 0.8 1.0 1.2 0.0 0.2 0.4 0.6 0.8 1.0 1.2 Normalized Concentration Normalized Concentration a. 50 m b. 100 m 250 200 ISC3_neutral ISC3_moderately_unstable ISC3_Very_unstable ADE_u*=0.3 ADE_u*=0.5 250 200 ISC3_neutral ISC3_moderately_unstable ISC3_Very_unstable ADE_u*=0.3 ADE_u*=0.5 hieght z (m) 150 100 hieght z (m) 150 100 50 50 0 0.0 0.2 0.4 0.6 0.8 1.0 1.2 Normalized Concentration 0 0.0 0.2 0.4 0.6 0.8 1.0 1.2 Normalized Concentration c. 500 m d. 1,000 m Figure 5-10. Comparison of ISC3 gaussian concentration profile and profile from numerical solution of Atmospheric Diffusion Equation at multiple downwind distances. Solutions for the ADE are for neutral conditions. 5-15
Page 1:
FIELD TESTING AND EVALUATION OF DUS
Page 5 and 6:
EXECUTIVE SUMMARY The Western State
Page 7 and 8:
models. Countess (2001) summarized
Page 9 and 10:
TABLE OF CONTENTS 1. INTRODUCTION 1
Page 11 and 12:
TABLE OF FIGURES Figure 2-1. Develo
Page 13 and 14:
Figure 4-6. The fraction of particl
Page 15 and 16:
Figure 5-16. Comparison of fraction
Page 17 and 18:
LIST OF TABLES Table 2-1. Parameter
Page 19 and 20:
1. INTRODUCTION 1.1 Background The
Page 21 and 22:
2.BACKGROUND Fugitive dust is emitt
Page 23 and 24:
Planetary Boundary Layer (PBL) F =
Page 25 and 26:
C D u* = ur The overall drag c
Page 27 and 28:
St a vg u g = cA L * Equation 2
Page 29 and 30:
Table 2-1. Parameters used in the S
Page 31 and 32:
1E+01 1E+00 z0 = 4.4 cm z0 = 6.4 cm
Page 33 and 34:
pathway for deposition for particle
Page 35 and 36:
An alternative method for modeling
Page 37 and 38: 3. MEASUREMENT OF DEPOSTION VELOCIT
Page 39 and 40: Department at the University of Uta
Page 41 and 42: In the laboratory, the deposited ma
Page 43 and 44: Table 3-2. Log of all flat substrat
Page 45 and 46: 16 Normalized Deposition Velocity 1
Page 47 and 48: 1.E+05 Deposition Velocity - cm/s 1
Page 49 and 50: are deposition from a horizontally
Page 51 and 52: single element that is intended to
Page 53 and 54: 4. MODELS USED TO STUDY PARTICLE RE
Page 55 and 56: κu ( ) * z 8 fz K zz = exp −
Page 57 and 58: C = −6 ( 1× 10 ) QV 2π u s σ
Page 59 and 60: oad. M is the mass of particles in
Page 61 and 62: By making the approximation that dm
Page 63 and 64: diameters less than 10 microns. Dis
Page 65 and 66: of such a height is somewhat arbitr
Page 67 and 68: 1 0.9 0.8 1 0.9 0.8 Fraction remain
Page 69 and 70: Fraction of Particles Remaining in
Page 71 and 72: gravitational settling. Stable cond
Page 73 and 74: though it is expected to improve at
Page 75 and 76: 5. DETERMINATION OF PARTICLE REMOVA
Page 77 and 78: PM 10 measured by the DustTrak must
Page 79 and 80: 100% 90% 80% Relative Frequency (pr
Page 81 and 82: average wind speed measured at 12 m
Page 83 and 84: where the subscript i indicates tha
Page 85 and 86: k C int = peakend k C peeakstart d
Page 87: Height z (m) 14 12 10 8 6 T1_data T
Page 92 and 93: Table 5-2 enumerates the speed-depe
Page 94 and 95: 6 Ratio of AP-42 Emission Factor to
Page 96 and 97: to the ground) giving an approximat
Page 98 and 99: models analyzed in this study is su
Page 100 and 101: Table 6-1. Screen analysis of test
Page 102 and 103: value which was used up to the midp
Page 104 and 105: measured at 3,1. Downwind the dust
Page 106 and 107: trips, the average readings for the
Page 108 and 109: Fraction of particles of stated siz
Page 110 and 111: the ground, where particles have a
Page 112 and 113: particles through the top of the bo
Page 114 and 115: deposition. Much of the decrease in
Page 116 and 117: 7-8
Page 118 and 119: Gifford, F.A. (1961). Use of Routin
Page 120: Venkatram, A. (1993). The Parametri
show all

FIELD TESTING AND EVALUATION OF DUST DEPOSITION AND ...

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?