Modelling component evaporation and composition change of traffic-induced ultrafine particles during travel from street canyon to urban background

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@article{ab4a95a9e9904f189fe87a8cce74b0a4,
title = "Modelling component evaporation and composition change of traffic-induced ultrafine particles during travel from street canyon to urban background",
abstract = "We developed a model (CiTTy-Street-UFP) of traffic-related particle behaviour in a street canyon and in the nearby downwind urban background that accounts for aerosol dynamics and the variable vapour pressure of component organics. The model simulates the evolution and fate of traffic generated multicomponent ultrafine particles (UFP) composed of a non-volatile core and 17 Semi-Volatile Organic Compounds (SVOC, modelled as n-alkane proxies). A twostage modelling approach is adopted: (1) a steady state simulation inside the street canyon is achieved, in which thereexists a balance between traffic emissions, condensation/evaporation, deposition, coagulation and exchange with the air above roof-level; and (2) a continuing simulation of the above-roof air parcel advected to the nearby urban park during which evaporation is dominant. We evaluate the component evaporation and associated composition changes of multicomponent organic particles in realistic atmospheric conditions and compare our results with observations from London (UK) in a street canyon and an urban park. With plausible input conditions and parameter settings, the modelcan reproduce, with reasonable fidelity, size distributions in central London in 2007. The modelled nucleation-mode peak diameter, which is 23 nm in the steady-state street canyon, decreases to 9 nm in a travel time of just 120 s. All modelled SVOC in the sub-10 nm particle size range have evaporated leaving behind only non-volatile material, whereas modelled particle composition in the Aitken mode contains SVOC between C26H54 and C32H66. No data on particle composition are available in the study used for validation, or elsewhere. Measurements addressing in detail thesize resolved composition of the traffic emitted UFP in the atmosphere are a high priority for future research. Such data would improve the representation of these particles in dispersion models and provide the data essential for model validation. Enhanced knowledge of the chemical composition of nucleation-mode particles from diesel engine exhaust is needed to predict both their atmospheric behaviour and their implications for human health.",
author = "Irina Nikolova and Mackenzie, {A. Rob} and Xiaoming Cai and Alam, {Mohammed S.} and Harrison, {Roy M.}",
year = "2016",
month = jan,
day = "4",
doi = "10.1039/C5FD00164A",
language = "English",
volume = "189",
pages = "529--546",
journal = "Faraday Discussions",
issn = "1359-6640",
publisher = "Royal Society of Chemistry",

}

RIS

TY - JOUR

T1 - Modelling component evaporation and composition change of traffic-induced ultrafine particles during travel from street canyon to urban background

AU - Nikolova, Irina

AU - Mackenzie, A. Rob

AU - Cai, Xiaoming

AU - Alam, Mohammed S.

AU - Harrison, Roy M.

PY - 2016/1/4

Y1 - 2016/1/4

N2 - We developed a model (CiTTy-Street-UFP) of traffic-related particle behaviour in a street canyon and in the nearby downwind urban background that accounts for aerosol dynamics and the variable vapour pressure of component organics. The model simulates the evolution and fate of traffic generated multicomponent ultrafine particles (UFP) composed of a non-volatile core and 17 Semi-Volatile Organic Compounds (SVOC, modelled as n-alkane proxies). A twostage modelling approach is adopted: (1) a steady state simulation inside the street canyon is achieved, in which thereexists a balance between traffic emissions, condensation/evaporation, deposition, coagulation and exchange with the air above roof-level; and (2) a continuing simulation of the above-roof air parcel advected to the nearby urban park during which evaporation is dominant. We evaluate the component evaporation and associated composition changes of multicomponent organic particles in realistic atmospheric conditions and compare our results with observations from London (UK) in a street canyon and an urban park. With plausible input conditions and parameter settings, the modelcan reproduce, with reasonable fidelity, size distributions in central London in 2007. The modelled nucleation-mode peak diameter, which is 23 nm in the steady-state street canyon, decreases to 9 nm in a travel time of just 120 s. All modelled SVOC in the sub-10 nm particle size range have evaporated leaving behind only non-volatile material, whereas modelled particle composition in the Aitken mode contains SVOC between C26H54 and C32H66. No data on particle composition are available in the study used for validation, or elsewhere. Measurements addressing in detail thesize resolved composition of the traffic emitted UFP in the atmosphere are a high priority for future research. Such data would improve the representation of these particles in dispersion models and provide the data essential for model validation. Enhanced knowledge of the chemical composition of nucleation-mode particles from diesel engine exhaust is needed to predict both their atmospheric behaviour and their implications for human health.

AB - We developed a model (CiTTy-Street-UFP) of traffic-related particle behaviour in a street canyon and in the nearby downwind urban background that accounts for aerosol dynamics and the variable vapour pressure of component organics. The model simulates the evolution and fate of traffic generated multicomponent ultrafine particles (UFP) composed of a non-volatile core and 17 Semi-Volatile Organic Compounds (SVOC, modelled as n-alkane proxies). A twostage modelling approach is adopted: (1) a steady state simulation inside the street canyon is achieved, in which thereexists a balance between traffic emissions, condensation/evaporation, deposition, coagulation and exchange with the air above roof-level; and (2) a continuing simulation of the above-roof air parcel advected to the nearby urban park during which evaporation is dominant. We evaluate the component evaporation and associated composition changes of multicomponent organic particles in realistic atmospheric conditions and compare our results with observations from London (UK) in a street canyon and an urban park. With plausible input conditions and parameter settings, the modelcan reproduce, with reasonable fidelity, size distributions in central London in 2007. The modelled nucleation-mode peak diameter, which is 23 nm in the steady-state street canyon, decreases to 9 nm in a travel time of just 120 s. All modelled SVOC in the sub-10 nm particle size range have evaporated leaving behind only non-volatile material, whereas modelled particle composition in the Aitken mode contains SVOC between C26H54 and C32H66. No data on particle composition are available in the study used for validation, or elsewhere. Measurements addressing in detail thesize resolved composition of the traffic emitted UFP in the atmosphere are a high priority for future research. Such data would improve the representation of these particles in dispersion models and provide the data essential for model validation. Enhanced knowledge of the chemical composition of nucleation-mode particles from diesel engine exhaust is needed to predict both their atmospheric behaviour and their implications for human health.

UR - http://www.scopus.com/inward/record.url?scp=84979060336&partnerID=8YFLogxK

U2 - 10.1039/C5FD00164A

DO - 10.1039/C5FD00164A

M3 - Article

AN - SCOPUS:84979060336

VL - 189

SP - 529

EP - 546

JO - Faraday Discussions

JF - Faraday Discussions

SN - 1359-6640

ER -