Vertical distribution of aerosol particles and NOx close to a motorway

Imhof, D.; Weingärtner, E.; Vogt, Ulrich; Dreiseidler, A.; Rosenbohm, E.; Scheer, Volker; Vogt, Rainer; Nielsen, Ole John; Kurtenbach, R.; Corsmeier, U.; Köhler, Martin; Baltensperger, Urs

doi:10.1016/j.atmosenv.2004.07.036

Cited by 52 publications

(30 citation statements)

References 25 publications

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“…If we divide the wind-induced power force − → F into components − → F n and − → F t , the flow affected by the power − → F n moves downwind, as a result of which the particle concentration downwind becomes higher. This was confirmed by the investigations [15] of the vertical distribution of aerosol particles and NO x close to a roadway on the downwind side carried out in Germany, when the wind speed was 2.2 m/s. It was determined that the former particle concentration maximum in the forenoon was near the ground surface, but at about noon it slightly shifted to 10 m above the ground for aerosol particles less than 0.3 µm, while upwind the aerosol particle concentration remained constant up to the 50 m height.…”

Section: Description Of a Physical Modelsupporting

confidence: 64%

Simulation of traffic pollution dispersion near roadways

Martinėnas¹,

Špakauskas²

2010

Lithuanian J. Phys.

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A semi-empirical model intended for simulation of dispersion of aerosol particles with the diameter larger than 0.05 µm near roadways is proposed. The pollution source is simulated as a cut-off cylinder, formed due to traffic pollution on the roadways at the initial time moment and uniformly filled with aerosol particles. The aerosol particle transfer by the wind further from the roadway is simulated, its settling being influenced by the gravitation, particle buoyancy, and thermal pollutant plume rise effects. Good agreement between the model and experimental results is obtained.

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Section: Description Of a Physical Modelsupporting

confidence: 64%

Simulation of traffic pollution dispersion near roadways

Martinėnas¹,

Špakauskas²

2010

Lithuanian J. Phys.

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“…Ketzel et al (2003) report an R 2 =0.81 for the particle number concentration (10-700 nm) and the NO x concentration. Very high correlations between NO x mixing ratio and the particle surface area concentration (R 2 =0.9) were obtained for a traffic aerosol in an open field experiment (Imhof et al, 2005b). Quite high correlations between PM2.5 and NO x (R 2 =0.62) as well as PM10 and NO x (R 2 =0.43) were also reported (Harrison et al, 2001).…”

Section: Resultsmentioning

confidence: 75%

Aerosol and NO<sub>x</sub> emission factors and submicron particle number size distributions in two road tunnels with different traffic regimes

et al. 2006

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Abstract. Measurements of aerosol particle number size distributions (18-700 nm), mass concentrations (PM2.5 and PM10) and NO x were performed in the Plabutsch tunnel, Austria, and in the Kingsway tunnel, United Kingdom. These two tunnels show different characteristics regarding the roadway gradient, the composition of the vehicle fleet and the traffic frequency. The submicron particle size distributions contained a soot mode in the diameter range D=80-100 nm and a nucleation mode in the range of D=20-40 nm. In the Kingsway tunnel with a significantly lower particle number and volume concentration level than in the Plabutsch tunnel, a clear diurnal variation of nucleation and soot mode particles correlated to the traffic density was observed. In the Plabutsch tunnel, soot mode particles also revealed a diurnal variation, whereas no substantial variation was found for the nucleation mode particles. During the night a higher number concentration of nucleation mode particles were measured than soot mode particles and vice versa during the day. In this tunnel with very high soot emissions during daytime due to the heavy-duty vehicle (HDV) share of 18% and another 40% of diesel driven lightduty vehicles (LDV) semivolatile species condense on the pre-existing soot surface area rather than forming new particles by homogeneous nucleation. With the low concentration of soot mode particles in the Kingsway tunnel, also the nucleation mode particles exhibit a diurnal variation. From the measured parameters real-world traffic emission factors were estimated for the whole vehicle fleet as well as differentiated into the two categories LDV and HDV. In the particle size range D=18-700 nm, each vehicle of the mixed fleet emits (1.50±0.08)×10 14 particles km −1 (Plabutsch)Correspondence to: E. Weingartner (ernest.weingartner@psi.ch) and (1.26±0.10)×10 14 particles km −1 (Kingsway), while particle volume emission factors of 0.209±0.008 cm 3 km −1 and 0.036±0.004 cm 3 km −1 , respectively, were obtained. PM1 emission factors of 104±4 mg km −1 (Plabutsch) and 41±4 mg km −1 (Kingsway) were calculated. Emission factors determined in this work were in good agreement with results from other studies.

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“…Revising the literature, the first peak (< 30 nm) is mainly attributed to carbonaceous particles directly emitted by gasoline emissions, and homogeneous nucleation from the supersaturation of semivolatile precursors due to the rapid cooling of both gasoline and diesel traffic exhaust gas (e.g., Imhof et al, 2005b). The second peak (50-100 nm) is indicative of diesel emissions, mainly soot aggregates from incomplete combustion processes (Imhof et al, 2005a). Ntziachristos et al (2007) found a mode at 70-80 nm in the proximity of freeways with high composition of diesel traffic in Los Angeles.…”

Section: Particle Number Size Distributionsmentioning

confidence: 99%

Characterisation and Source Apportionment of Submicron Particle Number Size Distributions in a Busy Street Canyon

Krecl

Targino

Johansson

et al. 2015

Aerosol Air Qual. Res.

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Street canyons are well-known hot spots due to the harmful exposure to high concentrations of atmospheric pollutants emitted mainly by motor vehicles. We report on measurements of air pollutants conducted in a street canyon in Stockholm (Sweden) in spring 2006. Particle number size distributions (PNSD) were measured in the 25-606 nm range, along with total particle number, light-absorbing carbon mass concentration (M LAC ), PM 10 , NO x , CO, traffic rate (TR), vehicle speed and meteorological variables. We used PNSD as input to the positive matrix factorisation (PMF) analysis to identify and apportion the pollutant sources. All pollutants showed distinct diurnal patterns, with highest concentrations in weekday mornings (08:00-09:00). TR was always higher on weekdays, except for the early hours (00:00-06:00). The raise in the weekend early-hour TR was accompanied by the largest M LAC of the day, a higher NO x /CO ratio compared to weekdays and a modal shift of PNSD towards larger diameters (47-56 nm), indicates a change in the vehicle fleet share to being dominated by diesel-run taxis. The largest contribution to the submicron particles was observed for winds blowing along the canyon, transporting particles emitted by vehicles accelerating from the traffic lights at the intersection, uphill towards the measurement site, and from the nearby streets. Three PMF factors were identified: local emissions from a mixed fleet dominated by gasoline engines, local traffic emissions highly impacted by diesel vehicles, and urban background aerosol. On average, gasoline-fuelled vehicles largely contributed to NO x , and particle number concentrations (54-65%), whereas M LAC sources were dominated by diesel emissions, especially at weekends in the early hours (73%). The urban background contribution was rather low (4-13%) and with little dependence on the weekday. This work demonstrated how particle size distribution measurements, together with M LAC , NO x and CO can be used to quantify the contribution from diesel and gasoline vehicles.

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Vertical distribution of aerosol particles and NOx close to a motorway

Cited by 52 publications

References 25 publications

Simulation of traffic pollution dispersion near roadways

Simulation of traffic pollution dispersion near roadways

Aerosol and NO<sub>x</sub> emission factors and submicron particle number size distributions in two road tunnels with different traffic regimes

Characterisation and Source Apportionment of Submicron Particle Number Size Distributions in a Busy Street Canyon

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Vertical distribution of aerosol particles and NOx close to a motorway

Cited by 52 publications

References 25 publications

Simulation of traffic pollution dispersion near roadways

Simulation of traffic pollution dispersion near roadways

Aerosol and NO&lt;sub&gt;x&lt;/sub&gt; emission factors and submicron particle number size distributions in two road tunnels with different traffic regimes

Characterisation and Source Apportionment of Submicron Particle Number Size Distributions in a Busy Street Canyon

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Aerosol and NO<sub>x</sub> emission factors and submicron particle number size distributions in two road tunnels with different traffic regimes