# Online CHARON PTR-ToF-MS measurements elucidate residential heating as the major contributor of wintertime organic aerosol in Fairbanks, Alaska

Amna Ijaz, Brice Temime-Roussel, Brice Barret, Bekki Slimane, Natalie

Brett, Meeta Cesler-Maloney, Javier Fochesatto, Benjamin Chazeau, Joel

Savarino, Kathy S. Law, et al.

► To cite this version:

Amna Ijaz, Brice Temime-Roussel, Brice Barret, Bekki Slimane, Natalie Brett, et al. Online CHARON PTR-ToF-MS measurements elucidate residential heating as the major contributor of wintertime organic aerosol in Fairbanks, Alaska. EGU General Assembly 2024, Apr 2024, Vienna, Austria. pp.EGU24-11073, 10.5194/egusphere-egu24-11073 . insu-04508001

HAL Id: insu-04508001

https://insu.hal.science/insu-04508001

Submitted on 31 May 2024

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# Online CHARON PTR-ToF-MS measurements elucidate residential heating as the major contributor of wintertime organic aerosol in Fairbanks, Alaska

Amna Ijaz, Brice Temime-Roussel, Brice Barret, Bekki Slimane, Natalie

Brett, Meeta Cesler-Maloney, Javier Fochesatto, Benjamin Chazeau, Joel

Savarino, Kathy S. Law, et al.

► To cite this version:

Amna Ijaz, Brice Temime-Roussel, Brice Barret, Bekki Slimane, Natalie Brett, et al. Online CHARON PTR-ToF-MS measurements elucidate residential heating as the major contributor of wintertime organic aerosol in Fairbanks, Alaska. EGU General Assembly 2024, Apr 2024, Vienna, Austria. pp.EGU24-11073, 10.5194/egusphere-egu24-11073 . insu-04508001

HAL Id: insu-04508001

https://insu.hal.science/insu-04508001v1

Submitted on 31 May 2024

**HAL** is a multi-disciplinary open access
archive for the deposit and dissemination of sci-
entific research documents, whether they are pub-
lished or not. The documents may come from
teaching and research institutions in France or
abroad, or from public or private research centers.

L'archive ouverte pluridisciplinaire HAL, est
destinée au dépôt et à la diffusion de documents
scientifiques de niveau recherche, publiés ou non,
émanant des établissements d'enseignement et de
recherche français ou étrangers, des laboratoires
publics ou privés.

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Distributed under a Creative Commons Attribution 4.0 International License
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# Online CHARON PTR-ToF-MS measurements elucidate residential heating as the major contributor of wintertime organic aerosol in Fairbanks, Alaska

Amna Ijaz<fnref n="1" />, Brice Temime-Roussel<fnref n="1" />, Brice Barret<fnref n="2" />, Bekki Slimane<fnref n="3" />, Nathalie Brett<fnref n="3" />, Meeta Cesler-Maloney<fnref n="4" />, Javier Fochesatto<fnref n="4" />, Benjamin Chazeau<fnref n="1" />, Joel Savarino<fnref n="5" />, Kathy Law<fnref n="3" />, William Simpson<fnref n="4" />, and Barbara D'Anna<fnref n="1" />

Fairbanks, central Alaska, is a sub-Arctic city that frequently suffers from non-attainment of national air quality standards in the wintertime due to the coincidence of weak atmospheric dispersion and increased local emissions but large uncertainties exist about aerosol sources and formation. We determined the general composition and mass concentrations of atmospheric sub-micron non-refractory particulate matter (NR-PM₁) and quantified the sources involved in its formation during a 6-week campaign in the urban centre of Fairbanks in January-February 2022. As part of the Alaskan Layered Pollution and Chemical Analysis campaign (ALPACA), we deployed a Chemical Analysis of Aerosol Online (CHARON) inlet coupled with a proton transfer reaction - time of flight mass spectrometer (PTR-ToF 6000 Ionicon Analytik) and high-resolution aerosol mass spectrometer (HR-ToF-AMS Aerodyne) to measure organic aerosol (OA) and NR-PM₁, respectively, with high temporal resolution of ≤1 min. We performed positive matrix factorisation (PMF) of the measurements to apportion aerosol mass to potential sources. The ability of HR-ToF-AMS to measure inorganic species (ammonium, nitrates, sulphates, and chlorides) creates an opportunity to gain insights into their mixing with OA and chemical dynamics. Campaign-averages of OA measured with the two instruments agreed reasonably well (R<fnref n="2" /> = 0.60) with a regression slope of 0.46. Higher OA concentrations observed with the HR-ToF-AMS are attributable to the particle size-dependence of the CHARON inlet, since it is more sensitive to particles >150 nm; a regression slope approaching 1.0 was achieved for larger primary OA emissions from biomass burning. On the one hand, in line with known emission patterns in Fairbanks, PMF indicated residential heating (Res-H) to be the single largest source of OA here during the wintertime as per CHARON PTR-ToF-MS measurements. A large fraction of OA originated from the combustion of different types of wood (2.07 ± 2.47 µg/m<fnref n="3" />; 47.15 ± 20.15%) and fuel oil (0.64 ± 0.64 µg/m<fnref n="3" />; 16.20 ± 9.73%) as determined from molecular composition and temporal correlation with external tracers (e.g., trace gases and marker ions). On the other hand, using HR-ToF-AMS data, neither OA, nor the overall NR-

<footnote n="1">¹Laboratoire Chimie Environment, CNRS, Marseille, France (barbara.danna@univ-amu.fr)</footnote>

<footnote n="2">²Laboratoire d'aérologie (LAERO/OMP - CNRS, Université Toulouse III - Paul Sabatier)</footnote>

<footnote n="3">³LATMOS/IPSL, Sorbonne Université, UVSQ, CNRS, Paris, France</footnote>

<footnote n="4">⁴Department of Chemistry and Biochemistry & Geophysical Institute, University of Alaska, Fairbanks, AK, USA</footnote>

<footnote n="5">⁵University of Grenoble Alpes, CNRS, IRD, Grenoble INP, INRAE, IGE, F-38000 Grenoble, France</footnote>
<figure><img src="image_2.png" /></figure>

# Online CHARON PTR-ToF-MS measurements elucidate residential heating as the major contributor of wintertime organic aerosol in Fairbanks, Alaska

Amna Ijaz<fnref n="1" />, Brice Temime-Roussel<fnref n="1" />, Brice Barret<fnref n="2" />, Bekki Slimane<fnref n="3" />, Nathalie Brett<fnref n="3" />, Meeta Cesler-Maloney<fnref n="4" />, Javier Fochesatto<fnref n="4" />, Benjamin Chazeau<fnref n="1" />, Joel Savarino<fnref n="5" />, Kathy Law<fnref n="3" />, William Simpson<fnref n="4" />, and Barbara D'Anna<fnref n="1" />

Fairbanks, central Alaska, is a sub-Arctic city that frequently suffers from non-attainment of national air quality standards in the wintertime due to the coincidence of weak atmospheric dispersion and increased local emissions but large uncertainties exist about aerosol sources and formation. We determined the general composition and mass concentrations of atmospheric sub-micron non-refractory particulate matter (NR-PM₁) and quantified the sources involved in its formation during a 6-week campaign in the urban centre of Fairbanks in January-February 2022. As part of the Alaskan Layered Pollution and Chemical Analysis campaign (ALPACA), we deployed a Chemical Analysis of Aerosol Online (CHARON) inlet coupled with a proton transfer reaction - time of flight mass spectrometer (PTR-ToF 6000 Ionicon Analytik) and high-resolution aerosol mass spectrometer (HR-ToF-AMS Aerodyne) to measure organic aerosol (OA) and NR-PM₁, respectively, with high temporal resolution of ≤1 min. We performed positive matrix factorisation (PMF) of the measurements to apportion aerosol mass to potential sources. The ability of HR-ToF-AMS to measure inorganic species (ammonium, nitrates, sulphates, and chlorides) creates an opportunity to gain insights into their mixing with OA and chemical dynamics. Campaign-averages of OA measured with the two instruments agreed reasonably well (R<fnref n="2" /> = 0.60) with a regression slope of 0.46. Higher OA concentrations observed with the HR-ToF-AMS are attributable to the particle size-dependence of the CHARON inlet, since it is more sensitive to particles >150 nm; a regression slope approaching 1.0 was achieved for larger primary OA emissions from biomass burning. On the one hand, in line with known emission patterns in Fairbanks, PMF indicated residential heating (Res-H) to be the single largest source of OA here during the wintertime as per CHARON PTR-ToF-MS measurements. A large fraction of OA originated from the combustion of different types of wood (2.07 ± 2.47 µg/m<fnref n="3" />; 47.15 ± 20.15%) and fuel oil (0.64 ± 0.64 µg/m<fnref n="3" />; 16.20 ± 9.73%) as determined from molecular composition and temporal correlation with external tracers (e.g., trace gases and marker ions). On the other hand, using HR-ToF-AMS data, neither OA, nor the overall NR-

<footnote n="1">¹Laboratoire Chimie Environment, CNRS, Marseille, France (barbara.danna@univ-amu.fr)</footnote>

<footnote n="2">²Laboratoire d'aérologie (LAERO/OMP - CNRS, Université Toulouse III - Paul Sabatier)</footnote>

<footnote n="3">³LATMOS/IPSL, Sorbonne Université, UVSQ, CNRS, Paris, France</footnote>

<footnote n="4">⁴Department of Chemistry and Biochemistry & Geophysical Institute, University of Alaska, Fairbanks, AK, USA</footnote>

<footnote n="5">⁵University of Grenoble Alpes, CNRS, IRD, Grenoble INP, INRAE, IGE, F-38000 Grenoble, France</footnote>
PM₁, could be delineated into multiple Res-H sources, and only a single Biomass Burning (BB)-OA related factor could be identified. With the HR-ToF-AMS data, hydrocarbon-like OA (HOA) also appeared as another important contributor to OA (2.08 ± 2.79 µg/m³; 38.07 ± 20.38%), other than BBOA (1.47 ± 1.81 µg/m³; 28.01 ± 18.91%). In addition, while HOA (or traffic), cooking, and BBOA emissions are almost completely (> 90% of mass) composed of organics, the PMF analysis revealed inorganic aerosol to be distributed across two secondary aerosol factors, i.e., sulphur-rich oxygenated OA and ammonium nitrate, as well as an acidic sulphate aerosol factor. The insights obtained here demonstrate that CHARON PTR-ToF-MS not only provides robust quantitative information but, when combined with a suitable complementary instrument, it generates more refined evidence-based understanding of the dominant sources of OA and processes forming NR-PM₁ which are key to endorsing policy and citizen efforts for the prevention and control of air pollution in Fairbanks, and in the wider Arctic winter.
PM₁, could be delineated into multiple Res-H sources, and only a single Biomass Burning (BB)-OA related factor could be identified. With the HR-ToF-AMS data, hydrocarbon-like OA (HOA) also appeared as another important contributor to OA (2.08 ± 2.79 µg/m³; 38.07 ± 20.38%), other than BBOA (1.47 ± 1.81 µg/m³; 28.01 ± 18.91%). In addition, while HOA (or traffic), cooking, and BBOA emissions are almost completely (> 90% of mass) composed of organics, the PMF analysis revealed inorganic aerosol to be distributed across two secondary aerosol factors, i.e., sulphur-rich oxygenated OA and ammonium nitrate, as well as an acidic sulphate aerosol factor. The insights obtained here demonstrate that CHARON PTR-ToF-MS not only provides robust quantitative information but, when combined with a suitable complementary instrument, it generates more refined evidence-based understanding of the dominant sources of OA and processes forming NR-PM₁ which are key to endorsing policy and citizen efforts for the prevention and control of air pollution in Fairbanks, and in the wider Arctic winter.