The entrapment of particles by windbreaks

Raupach, Michael; Woods, N.; Dorr, G. J.; Leys, John; Cleugh, Helen

doi:10.1016/s1352-2310(01)00139-x

Cited by 135 publications

(116 citation statements)

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“…The effects of windbreaks on airflow and turbulence have been described in several reports [42][43][44]. Raupach et al [42] found that the fraction of particles in the oncoming flow that pass through the windbreak, or transmittance of the windbreak to particles, is related to the optical porosity. The total deposition of particles has been determined by an exchange of the particle absorption and transmission, and maximum total deposition corresponds to an optimum porosity value.…”

Section: Introductionmentioning

confidence: 99%

The Concentrations and Reduction of Airborne Particulate Matter (PM10, PM2.5, PM1) at Shelterbelt Site in Beijing

Chen

Sun

et al. 2015

Atmosphere

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Particulate matter is a serious source of air pollution in urban areas, where it exerts adverse effects on human health. This article focuses on the study of subduction of shelterbelts for atmospheric particulates. The results suggest that (1) the PM mass concentration is higher in the morning or both morning and noon inside the shelterbelts and lower mass concentrations at other times; (2) the particle mass concentration inside shelterbelt is higher than outside; (3) the particle interception efficiency of the two forest belts over the three months in descending order was PM10 > PM1 > PM2.5; and (4) the two shelterbelts captured air pollutants at rates of 1496.285 and 909.075 kg/month and the major atmospheric pollutant in Beijing city is PM10. Future research directions are to study PM mass concentration variation of shelterbelt with different tree species and different configuration.

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Section: Introductionmentioning

confidence: 99%

The Concentrations and Reduction of Airborne Particulate Matter (PM10, PM2.5, PM1) at Shelterbelt Site in Beijing

Chen

Sun

et al. 2015

Atmosphere

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“…where F z (g/m 2 /s) is the vertical flux of particles at a height z and is equal to the vertical (z-direction) dispersion coefficient K zz (m 2 /s) multiplied by the negative of the vertical concentration gradient (g/m 4 ). Similar equations are used to describe dispersion in the two horizontal directions with the coefficients K xx and K yy , which may be close in magnitude to one another but can be quite different from K zz .…”

Section: Introductionmentioning

confidence: 99%

“…4,[15][16][17] Most of the models developed to study dry deposition of sulfate and other pollutants from the atmosphere are derived for the well-mixed conditions of region C in Figure 1. The flux to the ground is assumed to be equal to the concentration measured at a given height multiplied by a transfer coefficient, which is also dependent on height.…”

Section: Introductionmentioning

confidence: 99%

Deposition and Removal of Fugitive Dust in the Arid Southwestern United States: Measurements and Model Results

Etyemezian

Ahonen

Nikolić

et al. 2004

Journal of the Air & Waste Management Association

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This work was motivated by the need to better reconcile emission factors for fugitive dust with the amount of geologic material found on ambient filter samples. The deposition of particulate matter with aerodynamic diameter less than or equal to 10 m (PM 10 ), generated by travel over an unpaved road, over the first 100 m of transport downwind of the road was examined at Ft. Bliss, near El Paso, TX. The field conditions, typical for warm days in the arid southwestern United States, represented sparsely vegetated terrain under neutral to unstable atmospheric conditions. Emission fluxes of PM 10 dust were obtained from towers downwind of the unpaved road at 7, 50, and 100 m. The horizontal flux measurements at the 7 m and 100 m towers indicated that PM 10 deposition to the vegetation and ground was too small to measure. The data indicated, with 95% confidence, that the loss of PM 10 between the source of emission at the unpaved road, represented by the 7 m tower, and a point 100 m downwind was less than 9.5%. A Gaussian model was used to simulate the plume. Values of the vertical standard deviation z and the deposition velocity V d were similar to the U.S. Environmental Protection Agency (EPA) ISC3 model. For the field conditions, the model predicted that removal of PM 10 unpaved road dust by deposition over the distance between the point of emission and 100 m downwind would be less than 5%. However, the model results also indicated that particles larger than 10 m (aerodynamic diameter) would deposit more appreciably. The model was consistent with changes observed in size distributions between 7 m and 100 m downwind, which were measured with optical particle counters. The Gaussian model predictions were also compared with another study conducted over rough terrain and stable atmospheric conditions. Under such conditions, measured PM 10 removal rates over 95 m of downwind transport were reported to be between 86% and 89%, whereas the Gaussian model predicted only a 30% removal. One explanation for the large discrepancy between measurements and model results was the possibility that under the conditions of the study, the dust plume was comparable in vertical extent to the roughness elements, thereby violating one of the model assumptions. Results of the field study reported here and the previous work over rough terrain bound the extent of particle deposition expected to occur under most unpaved road emission scenarios. IMPLICATIONSThis work was motivated by the well-documented disagreement between estimates of road and other geological dust obtained by emissions inventory methods and the actual amount of inorganic minerals observed on filter samples at ambient monitoring sites. This study provides a basis for modeling the magnitude of PM 10 dust removal by deposition close to the emission source. The analysis focuses on emissions from unpaved roads, though the results may be pertinent to other sources of fugitive dust. TECHNICAL PAPER INTRODUCTIONFugitive dust is emitted from an unpaved road when a vehicle ...

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“…The formula used for the correction factor is discussed in section 2.3.1. The removal of the particles via dry deposition is modelled by a product of three parameters: leaf area density (LAD), defined as a leaf area per unit volume (m 2 m −3 ), deposition velocity u d (m s −1 ) measuring the filtration efficiency of the vegetation under given conditions, and the particle concentration (Raupach et al, 2001b). Its form is discussed in section 2.3.…”

Section: Number Concentration Equationmentioning

confidence: 99%

Dry deposition model for a microscale aerosol dispersion solver based on the moment method

Šíp

Beneš

2017

Journal of Aerosol Science

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A dry deposition model suitable for use in the moment method has been developed. Contributions from five main processes driving the deposition -Brownian diffusion, interception, impaction, turbulent impaction, and sedimentation -are included in the model. The deposition model was employed in the moment method solver implemented in the OpenFOAM framework. Applicability of the developed expression and the moment method solver was tested on two example problems of particle dispersion in the presence of a vegetation on small scales: a flow through a tree patch in 2D and a flow through a hedgerow in 3D. Comparison with the sectional method showed that the moment method using the developed deposition model is able to reproduce the shape of the particle size distribution well. The relative difference in terms of the third moment of the distribution was below 10% in both tested cases, and decreased away from the vegetation. Main source of this difference is a known overprediction of the impaction efficiency. When tested on the 3D test case, the moment method achieved approximately eightfold acceleration compared to the sectional method using 41 bins.

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The entrapment of particles by windbreaks

Cited by 135 publications

References 13 publications

The Concentrations and Reduction of Airborne Particulate Matter (PM10, PM2.5, PM1) at Shelterbelt Site in Beijing

The Concentrations and Reduction of Airborne Particulate Matter (PM10, PM2.5, PM1) at Shelterbelt Site in Beijing

Deposition and Removal of Fugitive Dust in the Arid Southwestern United States: Measurements and Model Results

Dry deposition model for a microscale aerosol dispersion solver based on the moment method

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