Effect of Soil Type and Momentum on Unpaved Road Particulate Matter Emissions from Wheeled and Tracked Vehicles

Figures & data

TABLE 1 Ratios of PM concentration based on size (PM₁₀ and PM_2.5) and measurement method (gravimetric and DustTrak) from bulk sample resuspension analysis. Uncertainties are standard deviations of the ratios. The number in parenthesis represents the number of replicates used to calculate the average

Sample location	Ratio of gravimetric PM10 to DustTrak	Ratio of gravimetric PM2.5 to DustTrak	Ratio of gravimetric PM10 to PM2.5	Ratio of dust PM10 to PM2.5
Ft. Bliss, TX∗	1.4 (1)	N/A	N/A	6.7 ± 3.2 (2)
Yakima,WA	1.7 ± 0.2 (6)	0.9 ± 0.2 (7)	4.0 ± 0.7 (7)	1.9 ± 0.3 (6)
Ft. Carson, CO (site 1)	2.1 ± 0.2 (4)	1.5 ± 0.1 (4)	5.7 ± 1.0 (4)	4.2 ± 0.2 (4)
Ft. Carson, CO (site 2)	1.7 ± 0.2 (4)	2.0 ± 0.2 (4)	6.4 ± 0.8 (4)	7.9 ± 0.7 (4)

TABLE 2 Flux calculation data recovery statistics from the Yakima and Ft. Carson vehicle dust flux experiments

	Yakima Training Center 2006			Ft. Carson Site 1 2008				Ft. Carson Site 2 2008
	Tower 1 PM10	Tower 1 PM2.5	Tower 2 PM10	Tower 1 PM2.5	Tower 1 PM10	Tower 2 PM10	Tower S PM10	Tower 1 PM2.5	Tower 1 PM10	Tower 2 PM10	Tower 3 PM10
Total Vehicle Passes	131	131	131	80	80	80	80	70	70	70	70
Data Acquisition Fault	2	0	3	0	0	18	0	0	0	0	0
WD outside of 45 deg perpendicular	6	6	6	7	7	7	7			4	4
Average of Top DustTrak on Tower > 1 mg/m3	7	0	9	11	11	11	11	70	70	22	22
Max of any DT > 150 mg/m3	118	73	92	0	0	0	0	0	0	0	0
Number Invalid due to Wind Direction or Top DT	12	6	14	18	18	18	18	70	70	26	26
Emission Factor Data Recovery
Class A: No Faults	8%	41%	27%	78%	78%	55%	78%	0%	0%	63%	63%
Class B: PM10 inferred from collocated PM2.5	31%
Class C: PM10 inferred from DT mounted above	52%	54%	63%
TOTAL	91%	95%	89%	78%	78%	55%	78%	0%	0%	63%	63%

FIG. 1 Comparison of gravimetric PM₁₀ emission factors versus vehicle speed from Ft. Bliss, Ft. Carson, and Yakima.

TABLE 3 Summary of surface material texture, emission factors, and cumulative PI-SWERL emissions for four test locations. Uncertainties are standard deviations of the emission factors. The number in parenthesis represents the number of replicate samples in the average. PI-SWERL measurements have different emission factor units and, like the silt content, are shown to provide a relative comparison

Sample location	Sand, silt, and clay content of surface material (SSURGO 2009)	Tracked gravimetric PM10 EF/momentum [g PM/vkt]/[kg ∗ m/s]	Wheeled gravimetric PM10 EF/momentum [g PM/vkt]/[kg ∗ m/s]	PI-SWERL cumulative gravimetric emissions (mg PM10/m^2 s) at u∗ = 0.2 m/s
Ft. Bliss	79% 16% 5%	0.006 ± 0.002 (54)	0.016 ± 0.008 (207)	N/A
Yakima	35% 48% 17%	0.4 ± 0.3 (246)	N/A	1.7 ± 0.8 (4)
Ft. Carson (site 1)	34% 32% 34%	0.006 ± 0.002 (157)	N/A	0.4 ± 0.2 (2)
Ft. Carson (site 2)	34% 32% 34%	0.004 ± 0.004 (34)	0.008 ± 0.003 (52)	0.2 ± 0.1 (2)

FIG. 2 Comparison of tracked vehicle PM₁₀ emission factors versus vehicle momentum for three different vehicles.

FIG. 3 Comparison of tracked and wheeled vehicle DustTrak emission factors versus vehicle momentum operating at the same locations.

FIG. 4 PI-SWERL P₁₀ emissions versus friction velocity from Yakima Training Center and Ft. Carson unpaved roads.

Kuhns , H. , Gillies , J. , Etyemezian , V. , Dubois , D. , Ahonen , S. , Nikolic , D. and Durham , C. 2005 . Spatial Variability of Unpaved Road Dust PM10 Emission Factors Near El Paso, Texas . J. Air & Waste Manage. Assoc. , 55 : 3 – 12 . (1995)

 PubMedGoogle Scholar

SSURGO . 2009 . Soil Survey Geographic Database, Natural Resources Conservation Service http://soils.usda.gov/survey/geography/ssurgo/

 Google Scholar