Chemical and physical characterization of traffic particles in four different highway environments in the Helsinki metropolitan area

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http://hdl.handle.net/10138/164542

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Enroth , J , Saarikoski , S , Niemi , J , Kousa , A , Jezek , I , Mocnik , G , Carbone , S , Kuuluvainen , H , Rönkkö , T , Hillamo , R & Pirjola , L 2016 , ' Chemical and physical characterization of traffic particles in four different highway environments in the Helsinki metropolitan area ' Atmospheric Chemistry and Physics , vol. 16 , no. 9 , pp. 5497-5512 . DOI: 10.5194/acp-16-5497-2016

Title: Chemical and physical characterization of traffic particles in four different highway environments in the Helsinki metropolitan area
Author: Enroth, Joonas; Saarikoski, Sanna; Niemi, Jarkko; Kousa, Anu; Jezek, Irena; Mocnik, Grisa; Carbone, Samara; Kuuluvainen, Heino; Rönkkö, Topi; Hillamo, Risto; Pirjola, Liisa
Contributor: University of Helsinki, Department
University of Helsinki, Division of Atmospheric Sciences and Geophysics (Department of Physics) (-2009)
University of Helsinki, Department of Physics (-2009)
Date: 2016
Language: eng
Number of pages: 16
Belongs to series: Atmospheric Chemistry and Physics
ISSN: 1680-7316
URI: http://hdl.handle.net/10138/164542
Abstract: Traffic-related pollution is a major concern in urban areas due to its deleterious effects on human health. The characteristics of the traffic emissions on four highway environments in the Helsinki metropolitan area were measured with a mobile laboratory, equipped with state-of-the-art instrumentation. Concentration gradients were observed for all traffic-related pollutants, particle number (CN), particulate mass (PM1), black carbon (BC), organics, and nitrogen oxides (NO and NO2). Flow dynamics in different environments appeared to be an important factor for the dilution of the pollutants. For example, the half-decay distances for the traffic-related CN concentrations varied from 8 to 83aEuro-m at different sites. The PM1 emissions from traffic mostly consisted of organics and BC. At the most open site, the ratio of organics to BC increased with distance to the highway, indicating condensation of volatile and semi-volatile organics on BC particles. These condensed organics were shown to be hydrocarbons as the fraction of hydrocarbon fragments in organics increased. Regarding the CN size distributions, particle growth during the dilution was not observed; however the mass size distributions measured with a soot particle aerosol mass spectrometer (SP-AMS), showed a visible shift of the mode, detected at aEuro-100aEuro-nm at the roadside, to a larger size when the distance to the roadside increased. The fleet average emission factors appeared to be lower for the CN and higher for the NO2 than ten years ago. The reason is likely to be the increased fraction of light-duty (LD) diesel vehicles in the past ten years. The fraction of heavy-duty (HD) traffic, although constituting less than 10aEuro-% of the total traffic flow, was found to have a large impact on the emissions.
Subject: AEROSOL MASS-SPECTROMETER
AIR-POLLUTANT CONCENTRATIONS
LOW-PRESSURE IMPACTOR
DUTY DIESEL VEHICLE
3 TEXAS ROADWAYS
ULTRAFINE PARTICLES
NUMBER CONCENTRATION
PARTICULATE MATTER
SIZE-DISTRIBUTION
BLACK CARBON
114 Physical sciences
1172 Environmental sciences
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