Elucidating real-world vehicle emission factors from mobile measurements over a large metropolitan region: a focus on isocyanic acid, hydrogen cyanide, and black carbon

Elucidating real-world vehicle emission factors from mobile measurements over a large metropolitan region: a focus on isocyanic acid, hydrogen cyanide, and black carbon

<p>A mobile laboratory equipped with state-of-the-art gaseous and particulate instrumentation was deployed across the Greater Toronto Area (GTA) during two seasons. A high-resolution time-of-flight chemical ionization mass spectrometer (HR-TOF-CIMS) measured isocyanic acid (HNCO) and hydrogen...

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Main Authors: S. N. Wren, J. Liggio, Y. Han, K. Hayden, G. Lu, C. M. Mihele, R. L. Mittermeier, C. Stroud, J. J. B. Wentzell, J. R. Brook
Format: Article
Language:English
Published: Copernicus Publications 2018-11-01
Series:Atmospheric Chemistry and Physics
Online Access:https://www.atmos-chem-phys.net/18/16979/2018/acp-18-16979-2018.pdf
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language English
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author S. N. Wren
J. Liggio
Y. Han
K. Hayden
G. Lu
C. M. Mihele
R. L. Mittermeier
C. Stroud
J. J. B. Wentzell
J. R. Brook
J. R. Brook
spellingShingle S. N. Wren
J. Liggio
Y. Han
K. Hayden
G. Lu
C. M. Mihele
R. L. Mittermeier
C. Stroud
J. J. B. Wentzell
J. R. Brook
J. R. Brook
Elucidating real-world vehicle emission factors from mobile measurements over a large metropolitan region: a focus on isocyanic acid, hydrogen cyanide, and black carbon
Atmospheric Chemistry and Physics
author_facet S. N. Wren
J. Liggio
Y. Han
K. Hayden
G. Lu
C. M. Mihele
R. L. Mittermeier
C. Stroud
J. J. B. Wentzell
J. R. Brook
J. R. Brook
author_sort S. N. Wren
title Elucidating real-world vehicle emission factors from mobile measurements over a large metropolitan region: a focus on isocyanic acid, hydrogen cyanide, and black carbon
title_short Elucidating real-world vehicle emission factors from mobile measurements over a large metropolitan region: a focus on isocyanic acid, hydrogen cyanide, and black carbon
title_full Elucidating real-world vehicle emission factors from mobile measurements over a large metropolitan region: a focus on isocyanic acid, hydrogen cyanide, and black carbon
title_fullStr Elucidating real-world vehicle emission factors from mobile measurements over a large metropolitan region: a focus on isocyanic acid, hydrogen cyanide, and black carbon
title_full_unstemmed Elucidating real-world vehicle emission factors from mobile measurements over a large metropolitan region: a focus on isocyanic acid, hydrogen cyanide, and black carbon
title_sort elucidating real-world vehicle emission factors from mobile measurements over a large metropolitan region: a focus on isocyanic acid, hydrogen cyanide, and black carbon
publisher Copernicus Publications
series Atmospheric Chemistry and Physics
issn 1680-7316
1680-7324
publishDate 2018-11-01
description <p>A mobile laboratory equipped with state-of-the-art gaseous and particulate instrumentation was deployed across the Greater Toronto Area (GTA) during two seasons. A high-resolution time-of-flight chemical ionization mass spectrometer (HR-TOF-CIMS) measured isocyanic acid (HNCO) and hydrogen cyanide (HCN), and a high-sensitivity laser-induced incandescence (HS-LII) instrument measured black carbon (BC). Results indicate that on-road vehicles are a clear source of HNCO and HCN and that their impact is more pronounced in the winter, when influences from biomass burning (BB) and secondary photochemistry are weakest. Plume-based and time-based algorithms were developed to calculate fleet-average vehicle emission factors (EFs); the algorithms were found to yield comparable results, depending on the pollutant identity. With respect to literature EFs for benzene, toluene, C2 benzene (sum of <i>m-</i>, <i>p-</i>, and <i>o</i>-xylenes and ethylbenzene), nitrogen oxides, particle number concentration (PN), and black carbon, the calculated EFs were characteristic of a relatively clean vehicle fleet dominated by light-duty vehicles (LDV). Our fleet-average EF for BC (median: 25&thinsp;mg&thinsp;kg<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M1" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mi mathvariant="normal">fuel</mi><mrow><mo>-</mo><mn mathvariant="normal">1</mn></mrow></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="15pt" height="17pt" class="svg-formula" dspmath="mathimg" md5hash="1a8c532b1720d0ea4f5d9751953cb03e"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-18-16979-2018-ie00001.svg" width="15pt" height="17pt" src="acp-18-16979-2018-ie00001.png"/></svg:svg></span></span>; interquartile range, IQR: 10–76&thinsp;mg&thinsp;kg<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M2" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mi mathvariant="normal">fuel</mi><mrow><mo>-</mo><mn mathvariant="normal">1</mn></mrow></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="15pt" height="17pt" class="svg-formula" dspmath="mathimg" md5hash="48fd5fdeb4645549a8bae777d7aa0128"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-18-16979-2018-ie00002.svg" width="15pt" height="17pt" src="acp-18-16979-2018-ie00002.png"/></svg:svg></span></span>) suggests that overall vehicular emissions of BC have decreased over time. However, the distribution of EFs indicates that a small proportion of high-emitters continue to contribute disproportionately to total BC emissions. We report the first fleet-average EF for HNCO (median: 2.3&thinsp;mg&thinsp;kg<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M3" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mi mathvariant="normal">fuel</mi><mrow><mo>-</mo><mn mathvariant="normal">1</mn></mrow></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="15pt" height="17pt" class="svg-formula" dspmath="mathimg" md5hash="e08f0bbebdfe31f89c0e2f6e51d785d1"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-18-16979-2018-ie00003.svg" width="15pt" height="17pt" src="acp-18-16979-2018-ie00003.png"/></svg:svg></span></span>, IQR: 1.4–4.2&thinsp;mg&thinsp;kg<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M4" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mi mathvariant="normal">fuel</mi><mrow><mo>-</mo><mn mathvariant="normal">1</mn></mrow></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="15pt" height="17pt" class="svg-formula" dspmath="mathimg" md5hash="fccb73420823b2a60e142c38952459d4"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-18-16979-2018-ie00004.svg" width="15pt" height="17pt" src="acp-18-16979-2018-ie00004.png"/></svg:svg></span></span>) and HCN (median: 0.52&thinsp;mg&thinsp;kg<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M5" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mi mathvariant="normal">fuel</mi><mrow><mo>-</mo><mn mathvariant="normal">1</mn></mrow></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="15pt" height="17pt" class="svg-formula" dspmath="mathimg" md5hash="85c4438be8656632e84fdb276e716b80"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-18-16979-2018-ie00005.svg" width="15pt" height="17pt" src="acp-18-16979-2018-ie00005.png"/></svg:svg></span></span>, IQR: 0.32–0.88&thinsp;mg&thinsp;kg<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M6" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mi mathvariant="normal">fuel</mi><mrow><mo>-</mo><mn mathvariant="normal">1</mn></mrow></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="15pt" height="17pt" class="svg-formula" dspmath="mathimg" md5hash="6d432e3c7b89e1482addd742dfbd47fe"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-18-16979-2018-ie00006.svg" width="15pt" height="17pt" src="acp-18-16979-2018-ie00006.png"/></svg:svg></span></span>). The distribution of the estimated EFs provides insight into the real-world variability of HNCO and HCN emissions and constrains the wide range of literature EFs obtained from prior dynamometer studies. The impact of vehicle emissions on urban HNCO levels can be expected to be further enhanced if secondary HNCO formation from vehicle exhaust is considered.</p>
url https://www.atmos-chem-phys.net/18/16979/2018/acp-18-16979-2018.pdf
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spelling doaj-ebc13b94c3aa4ae4bc04723bd10d08322020-11-24T21:03:01ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242018-11-0118169791700110.5194/acp-18-16979-2018Elucidating real-world vehicle emission factors from mobile measurements over a large metropolitan region: a focus on isocyanic acid, hydrogen cyanide, and black carbonS. N. Wren0J. Liggio1Y. Han2K. Hayden3G. Lu4C. M. Mihele5R. L. Mittermeier6C. Stroud7J. J. B. Wentzell8J. R. Brook9J. R. Brook10Air Quality Process Research Section, Air Quality Research Division, Environment and Climate Change Canada, 4905 Dufferin St., Toronto, ON, M3H 5T4, CanadaAir Quality Process Research Section, Air Quality Research Division, Environment and Climate Change Canada, 4905 Dufferin St., Toronto, ON, M3H 5T4, CanadaAir Quality Process Research Section, Air Quality Research Division, Environment and Climate Change Canada, 4905 Dufferin St., Toronto, ON, M3H 5T4, CanadaAir Quality Process Research Section, Air Quality Research Division, Environment and Climate Change Canada, 4905 Dufferin St., Toronto, ON, M3H 5T4, CanadaAir Quality Process Research Section, Air Quality Research Division, Environment and Climate Change Canada, 4905 Dufferin St., Toronto, ON, M3H 5T4, CanadaAir Quality Process Research Section, Air Quality Research Division, Environment and Climate Change Canada, 4905 Dufferin St., Toronto, ON, M3H 5T4, CanadaAir Quality Process Research Section, Air Quality Research Division, Environment and Climate Change Canada, 4905 Dufferin St., Toronto, ON, M3H 5T4, CanadaAir Quality Process Research Section, Air Quality Research Division, Environment and Climate Change Canada, 4905 Dufferin St., Toronto, ON, M3H 5T4, CanadaAir Quality Process Research Section, Air Quality Research Division, Environment and Climate Change Canada, 4905 Dufferin St., Toronto, ON, M3H 5T4, CanadaAir Quality Process Research Section, Air Quality Research Division, Environment and Climate Change Canada, 4905 Dufferin St., Toronto, ON, M3H 5T4, Canadacurrently at: Dalla Lana School of Public Health, Department of Chemical Engineering and Applied Chemistry, University of Toronto, 223 College St., Toronto, ON, M5T 1R4, Canada<p>A mobile laboratory equipped with state-of-the-art gaseous and particulate instrumentation was deployed across the Greater Toronto Area (GTA) during two seasons. A high-resolution time-of-flight chemical ionization mass spectrometer (HR-TOF-CIMS) measured isocyanic acid (HNCO) and hydrogen cyanide (HCN), and a high-sensitivity laser-induced incandescence (HS-LII) instrument measured black carbon (BC). Results indicate that on-road vehicles are a clear source of HNCO and HCN and that their impact is more pronounced in the winter, when influences from biomass burning (BB) and secondary photochemistry are weakest. Plume-based and time-based algorithms were developed to calculate fleet-average vehicle emission factors (EFs); the algorithms were found to yield comparable results, depending on the pollutant identity. With respect to literature EFs for benzene, toluene, C2 benzene (sum of <i>m-</i>, <i>p-</i>, and <i>o</i>-xylenes and ethylbenzene), nitrogen oxides, particle number concentration (PN), and black carbon, the calculated EFs were characteristic of a relatively clean vehicle fleet dominated by light-duty vehicles (LDV). Our fleet-average EF for BC (median: 25&thinsp;mg&thinsp;kg<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M1" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mi mathvariant="normal">fuel</mi><mrow><mo>-</mo><mn mathvariant="normal">1</mn></mrow></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="15pt" height="17pt" class="svg-formula" dspmath="mathimg" md5hash="1a8c532b1720d0ea4f5d9751953cb03e"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-18-16979-2018-ie00001.svg" width="15pt" height="17pt" src="acp-18-16979-2018-ie00001.png"/></svg:svg></span></span>; interquartile range, IQR: 10–76&thinsp;mg&thinsp;kg<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M2" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mi mathvariant="normal">fuel</mi><mrow><mo>-</mo><mn mathvariant="normal">1</mn></mrow></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="15pt" height="17pt" class="svg-formula" dspmath="mathimg" md5hash="48fd5fdeb4645549a8bae777d7aa0128"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-18-16979-2018-ie00002.svg" width="15pt" height="17pt" src="acp-18-16979-2018-ie00002.png"/></svg:svg></span></span>) suggests that overall vehicular emissions of BC have decreased over time. However, the distribution of EFs indicates that a small proportion of high-emitters continue to contribute disproportionately to total BC emissions. We report the first fleet-average EF for HNCO (median: 2.3&thinsp;mg&thinsp;kg<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M3" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mi mathvariant="normal">fuel</mi><mrow><mo>-</mo><mn mathvariant="normal">1</mn></mrow></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="15pt" height="17pt" class="svg-formula" dspmath="mathimg" md5hash="e08f0bbebdfe31f89c0e2f6e51d785d1"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-18-16979-2018-ie00003.svg" width="15pt" height="17pt" src="acp-18-16979-2018-ie00003.png"/></svg:svg></span></span>, IQR: 1.4–4.2&thinsp;mg&thinsp;kg<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M4" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mi mathvariant="normal">fuel</mi><mrow><mo>-</mo><mn mathvariant="normal">1</mn></mrow></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="15pt" height="17pt" class="svg-formula" dspmath="mathimg" md5hash="fccb73420823b2a60e142c38952459d4"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-18-16979-2018-ie00004.svg" width="15pt" height="17pt" src="acp-18-16979-2018-ie00004.png"/></svg:svg></span></span>) and HCN (median: 0.52&thinsp;mg&thinsp;kg<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M5" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mi mathvariant="normal">fuel</mi><mrow><mo>-</mo><mn mathvariant="normal">1</mn></mrow></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="15pt" height="17pt" class="svg-formula" dspmath="mathimg" md5hash="85c4438be8656632e84fdb276e716b80"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-18-16979-2018-ie00005.svg" width="15pt" height="17pt" src="acp-18-16979-2018-ie00005.png"/></svg:svg></span></span>, IQR: 0.32–0.88&thinsp;mg&thinsp;kg<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M6" display="inline" overflow="scroll" dspmath="mathml"><mrow><msubsup><mi/><mi mathvariant="normal">fuel</mi><mrow><mo>-</mo><mn mathvariant="normal">1</mn></mrow></msubsup></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="15pt" height="17pt" class="svg-formula" dspmath="mathimg" md5hash="6d432e3c7b89e1482addd742dfbd47fe"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-18-16979-2018-ie00006.svg" width="15pt" height="17pt" src="acp-18-16979-2018-ie00006.png"/></svg:svg></span></span>). The distribution of the estimated EFs provides insight into the real-world variability of HNCO and HCN emissions and constrains the wide range of literature EFs obtained from prior dynamometer studies. The impact of vehicle emissions on urban HNCO levels can be expected to be further enhanced if secondary HNCO formation from vehicle exhaust is considered.</p>https://www.atmos-chem-phys.net/18/16979/2018/acp-18-16979-2018.pdf

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