Dry deposition profile of small particles within a model spruce canopy

Ould-Dada, Zitouni

doi:10.1016/s0048-9697(01)00965-2

Cited by 45 publications

(24 citation statements)

References 33 publications

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“…Next, although this study illustrated the influence of some meteorological factors on the concentration in different land cover types, these factors were uncontrollable, and further studies are needed to assess the use of such relationships to reduce the pollutant concentration. Besides, deposition and absorption by plants are two ways of air quality improvement (Khan and Abbasi 2000;McDonald et al 2007;Shan et al 2007;Tiwary et al 2006Tiwary et al , 2008Wang 2011;Willis et al 2003), while the capture capacities of plants and deposition velocity in forests are also affected by or dependent on some other factors such as the canopy density, leaf area index, shelterbelt porosity, and plant microstructure (Reinap et al 2009;Wuyts et al 2008;Yang et al 2005;Ould-Dada 2002). This coeffect mechanism also needs to be set up to guide the construction of the green purification system.…”

Section: Resultsmentioning

confidence: 99%

Removal efficiency of particulate matters at different underlying surfaces in Beijing

Liu

Zhu

et al. 2015

Environ Sci Pollut Res

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Particulate matter (PM) pollution has been increasingly becoming serious in Beijing and has drawn the attention of the local government and general public. This study was conducted during early spring of 2013 and 2014 to monitor the concentration of PM at three different land surfaces (bare land, urban forest, and lake) in the Olympic Park in Beijing and to analyze its effect on the concentration of meteorological factors and the dry deposition onto different land cover types. The results showed that diurnal variation of PM concentrations at the three different land surfaces had no significant regulations, and sharp short-term increases in PM10 (particulate matter having an aerodynamic diameter <10 μm) occurred occasionally. The concentrations also differed from one land cover type to another at the same time, but the regulation was insignificant. The most important meteorological factor influencing the PM concentration is relative humidity; it is positively correlated with the PM concentration. While in the forests, the wind speed and irradiance also influenced the PM concentration by affecting the capture capacity of trees and dry deposition velocity. Other factors were not correlated with or influenced by the PM concentration. In addition, the hourly dry deposition in unit area (μg/m(2)) onto the three types of land surfaces and the removal efficiency based on the ratio of dry deposition and PM concentration were calculated. The results showed that the forest has the best removal capacity for both PM2.5 (particulate matter having an aerodynamic diameter <2.5 μm) and PM10 because of the faster deposition velocity and relatively low resuspension rate. The lake's PM10 removal efficiency is higher than that of the bare land because of the relatively higher PM resuspension rates on the bare land. However, the PM2.5 removal efficiency is lower than that of the bare land because of the significantly lower dry deposition velocity.

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Section: Resultsmentioning

confidence: 99%

Removal efficiency of particulate matters at different underlying surfaces in Beijing

Liu

Zhu

et al. 2015

Environ Sci Pollut Res

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“…Wind-tunnels of various types are common in studies of aerosol-deposition to vegetative collector arrangements (e.g., Wiman 1981;Kinnersley et al 1994;Ould-Dada 2002;Wuyts et al 2008). The tunnel employed in our experiments (Fig.…”

Section: Experimental Arrangementsmentioning

confidence: 99%

“…V L and V d values refer to the leaves' capability to capture an aerosol with distribution of mass with particle size as in Fig. 3 and that some studies based on detailed process modelling (Wiman and Å gren 1985) and wind-tunnel experiments (e.g., Ould-Dada 2002) suggest that deposition velocity can be higher for vegetation with smaller LAI. Further research is clearly needed to resolve these issues.…”

Section: Comparisons With Other Datamentioning

confidence: 99%

Oak leaves as aerosol collectors: relationships with wind velocity and particle size distribution. Experimental results and their implications

Reinap

Wiman

Svenningsson

et al. 2009

Trees

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Advancing the understanding of the aerosolcapture efficiencies of forest components such as leaves and needles, and of the mechanisms that underpin these efficiencies, is essential to the many related issues of forest turnover of nutrients and pollutants. For idealized collectors (such as artificial plates or cylinders) aerosolmechanics offers a means for calculating capture efficiencies. For living collectors, in particular deciduous leaves, experimental investigations become necessary to assist in formulating the sub-models of capture efficiency that are fundamental to the modelling of fluxes of aerosol-borne substances to forests. We here present wind-tunnel based methods and results for leaves of Quercus robur L. exposed to an aerosol whose mass versus aerodynamic particle size distribution is characterised by a geometric mean aerodynamic particle diameter around 1.2 lm and a geometric standard deviation around 1.8. With respect to that distribution, and founded on a specially designed leaf wash-off method, we obtained average oak-leaf capture efficiencies ranging from 0.006% of the approaching aerosol mass flux at wind-speed 2 ms -1 to 0.012% of the flux at wind-speeds 10 ms -1 , respectively. These values can be translated into deposition velocities (V d ) for a leaf ensemble with a given leaf area index (LAI). With LAI in the range 2-5 (commonly found in the field) and for windspeeds 2, 5 and 10 ms -1 , resulting V d -values would be 0.02-0.05, 0.05-0.13, and 0.2-0.6 cm/s, respectively. To the extent comparisons are possible, our capture efficiency values are at the low end of the range of values reported by other researchers. The strong wind-speed sensitivity of V d has implications for the deposition of aerosol-borne substances to forests for which wind regimes may shift as a result of climatic and land-use changes.

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“…Many field experiments and wind tunnel tests have been conducted to quantify the deposition velocities and capture efficiency of trees [5][6][7][8][9][10][11]. A field measure that determined the effects of trees on nitrous oxide distribution in street canyons revealed that trees considerably affected the accumulation of transported pollutants [12].…”

Section: Introductionmentioning

confidence: 99%

Numerical Investigation on the Effect of Avenue Trees on PM2.5 Dispersion in Urban Street Canyons

2017

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Abstract:The Reynolds-averaged Navier-Stokes (RANS) model and revised generalized drift flux model were used to investigate the characteristics of airflow fields and PM 2.5 dispersion in street canyons with a variety setting on tree crown morphologies (i.e., conical, spherical, and cylindrical), leaf area densities (LADs = 0.5, 1.5, and 2.5 m 2 /m 3 ), and street canyon aspect ratios (H/W = 0.5, 1.0, and 2.0). Results were as follows: (1) airflow fields were reversed in the presence of trees and enhanced with higher LAD; (2) air velocity decreased negligibly when LAD increased from 1.5 to 2.5, but significantly when LAD increased from 0.5 to 1.5; (3) tree crown morphologies, building aspect ratios, and LADs were interrelated. The comparison of PM 2.5 showed that the most critical situations in H/W = 0.5, 1.0, and 2.0 corresponded to LAD = 0.5 with a conical canopy; (4) the H/W = 1.0 and LAD = 1.5 scenario was identified as the most efficient combination for PM 2.5 capture; (5) the maximum PM 2.5 reduction ratio was ordered from low to high in the sequence of conical, spherical, and cylindrical canopies. At predestinated LADs and aspect ratio, Populus tomentosa with cylindrical crown morphology exhibited the best efficiency on PM 2.5 capture with a reduction ratio of 75% to 85% at pedestrian height.

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Dry deposition profile of small particles within a model spruce canopy

Cited by 45 publications

References 33 publications

Removal efficiency of particulate matters at different underlying surfaces in Beijing

Removal efficiency of particulate matters at different underlying surfaces in Beijing

Oak leaves as aerosol collectors: relationships with wind velocity and particle size distribution. Experimental results and their implications

Numerical Investigation on the Effect of Avenue Trees on PM2.5 Dispersion in Urban Street Canyons

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