Evaluation of the surface roughness effect on suspended particle deposition near unpaved roads. (December 2015)

• Record Type: Journal Article
• Authors: Zhu, Dongzi; Gillies, John A.; Etyemezian, Vicken; Nikolich, George; Shaw, William J.
• Is Part Of: Atmospheric environment. Volume 122(2015)
• Page Start: 541
• Page End: 551
• Publication Date: 2015-12
• Subjects: Atmospheric deposition -- Fugitive dust -- Near-source deposition -- Road dust -- PM10; Air -- Pollution -- Periodicals; Air -- Pollution -- Meteorological aspects -- Periodicals; 551.51
• DOI: 10.1016/j.atmosenv.2015.10.009
• Languages: English
• ISSNs: 1352-2310

Abstract

Abstract: The downwind transport and deposition of suspended dust raised by a vehicle driving on unpaved roads was studied for four differently vegetated surfaces in the USA states of Kansas and Washington, and one barren surface in Nevada. A 10 m high tower adjacent to the source (≈10 m downwind) and an array of multi-channel optical particle counters at three positions downwind of the source measured the flux of particles and the particle size distribution in the advecting dust plumes in the horizontal and vertical directions. Aerodynamic parameters such as friction velocity ( u * ) and surface roughness length ( z 0 ) were calculated from wind speed measurements made on the tower. Particle number concentration, PM10 mass exhibited an exponential decay along the direction of transport. Coarse particles accounted for ≈95% of the PM10 mass, at least to a downwind distance of 200 m from the source. PM10 removed by deposition was found to increase with increasing particle size and increasing surface roughness under similar moderate wind speed conditions. The surface of dense, long grass (1.2 m high and complete surface cover) had the greatest reduction of PM10 among the five surfaces tested due to deposition induced by turbulence effects created by the rougher surface and by enhanced particle impaction/interception effects to the grass blades. Highlights: Measurement road dust PM10 concentration evolution during near-source transport. Study PM horizontal & vertical transport by array of real-time particle counters. Estimate impacts of the roughness/vegetation on PM deposition under 5 surfaces. Rougher surface induced increased turbulence, thus increased PM deposition. Dense grass site has highest reduction by enhanced particle impaction/interception.