Articles | Volume 13, issue 5
https://doi.org/10.5194/acp-13-2827-2013
© Author(s) 2013. This work is distributed under
the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
https://doi.org/10.5194/acp-13-2827-2013
© Author(s) 2013. This work is distributed under
the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
Research article
| 
08 Mar 2013
Research article |
| 08 Mar 2013
Oxidation of elemental Hg in anthropogenic and marine airmasses
H. Timonen
Science and Technology Program, University of Washington-Bothell, Bothell, WA, USA
Air Quality Research, Finnish Meteorological Institute, Helsinki, Finland
J. L. Ambrose
Science and Technology Program, University of Washington-Bothell, Bothell, WA, USA
D. A. Jaffe
Science and Technology Program, University of Washington-Bothell, Bothell, WA, USA
Department of Atmospheric Sciences, University of Washington, Seattle, WA, USA
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Atmos. Chem. Phys., 25, 4907–4928, https://doi.org/10.5194/acp-25-4907-2025, https://doi.org/10.5194/acp-25-4907-2025, 2025
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Hector Navarro-Barboza, Jordi Rovira, Vincenzo Obiso, Andrea Pozzer, Marta Via, Andres Alastuey, Xavier Querol, Noemi Perez, Marjan Savadkoohi, Gang Chen, Jesus Yus-Díez, Matic Ivancic, Martin Rigler, Konstantinos Eleftheriadis, Stergios Vratolis, Olga Zografou, Maria Gini, Benjamin Chazeau, Nicolas Marchand, Andre S. H. Prevot, Kaspar Dallenbach, Mikael Ehn, Krista Luoma, Tuukka Petäjä, Anna Tobler, Jaroslaw Necki, Minna Aurela, Hilkka Timonen, Jarkko Niemi, Olivier Favez, Jean-Eudes Petit, Jean-Philippe Putaud, Christoph Hueglin, Nicolas Pascal, Aurélien Chauvigné, Sébastien Conil, Marco Pandolfi, and Oriol Jorba
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Aerosol Research, 3, 113–124, https://doi.org/10.5194/ar-3-113-2025, https://doi.org/10.5194/ar-3-113-2025, 2025
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Magdalena Okuljar, Olga Garmash, Miska Olin, Joni Kalliokoski, Hilkka Timonen, Jarkko V. Niemi, Pauli Paasonen, Jenni Kontkanen, Yanjun Zhang, Heidi Hellén, Heino Kuuluvainen, Minna Aurela, Hanna E. Manninen, Mikko Sipilä, Topi Rönkkö, Tuukka Petäjä, Markku Kulmala, Miikka Dal Maso, and Mikael Ehn
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Sanna Saarikoski, Heidi Hellén, Arnaud P. Praplan, Simon Schallhart, Petri Clusius, Jarkko V. Niemi, Anu Kousa, Toni Tykkä, Rostislav Kouznetsov, Minna Aurela, Laura Salo, Topi Rönkkö, Luis M. F. Barreira, Liisa Pirjola, and Hilkka Timonen
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Joel Kuula, Hilkka Timonen, Jarkko V. Niemi, Hanna E. Manninen, Topi Rönkkö, Tareq Hussein, Pak Lun Fung, Sasu Tarkoma, Mikko Laakso, Erkka Saukko, Aino Ovaska, Markku Kulmala, Ari Karppinen, Lasse Johansson, and Tuukka Petäjä
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Pak Lun Fung, Martha A. Zaidan, Jarkko V. Niemi, Erkka Saukko, Hilkka Timonen, Anu Kousa, Joel Kuula, Topi Rönkkö, Ari Karppinen, Sasu Tarkoma, Markku Kulmala, Tuukka Petäjä, and Tareq Hussein
Atmos. Chem. Phys., 22, 1861–1882, https://doi.org/10.5194/acp-22-1861-2022, https://doi.org/10.5194/acp-22-1861-2022, 2022
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We developed an input-adaptive mixed-effects model, which was automatised to select the best combination of input variables, including up to three fixed effect variables and three time indictors as random effect variables. We tested the model to estimate lung-deposited surface area (LDSA), which correlates well with human health. The results show the inclusion of time indicators improved the sensitivity and the accuracy of the model so that it could serve as a network of virtual sensors.
Sanna Saarikoski, Jarkko V. Niemi, Minna Aurela, Liisa Pirjola, Anu Kousa, Topi Rönkkö, and Hilkka Timonen
Atmos. Chem. Phys., 21, 14851–14869, https://doi.org/10.5194/acp-21-14851-2021, https://doi.org/10.5194/acp-21-14851-2021, 2021
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This study presents the main sources of black carbon (BC) at two urban environments. The largest fraction of BC originated from biomass burning at the residential site (38 %) and from vehicular emissions (57 %) in the street canyon. Also, a significant fraction of BC was associated with urban background or long-range transport. The data are needed by modelers and authorities when assessing climate and air quality impact of BC as well as directing the emission legislation and mitigation actions.
Evelyn Freney, Karine Sellegri, Alessia Nicosia, Leah R. Williams, Matteo Rinaldi, Jonathan T. Trueblood, André S. H. Prévôt, Melilotus Thyssen, Gérald Grégori, Nils Haëntjens, Julie Dinasquet, Ingrid Obernosterer, France Van Wambeke, Anja Engel, Birthe Zäncker, Karine Desboeufs, Eija Asmi, Hilkka Timonen, and Cécile Guieu
Atmos. Chem. Phys., 21, 10625–10641, https://doi.org/10.5194/acp-21-10625-2021, https://doi.org/10.5194/acp-21-10625-2021, 2021
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Magdalena Okuljar, Heino Kuuluvainen, Jenni Kontkanen, Olga Garmash, Miska Olin, Jarkko V. Niemi, Hilkka Timonen, Juha Kangasluoma, Yee Jun Tham, Rima Baalbaki, Mikko Sipilä, Laura Salo, Henna Lintusaari, Harri Portin, Kimmo Teinilä, Minna Aurela, Miikka Dal Maso, Topi Rönkkö, Tuukka Petäjä, and Pauli Paasonen
Atmos. Chem. Phys., 21, 9931–9953, https://doi.org/10.5194/acp-21-9931-2021, https://doi.org/10.5194/acp-21-9931-2021, 2021
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To estimate the relative contribution of different sources to the particle population in an urban environment, we conducted simultaneous measurements at a street canyon and an urban background station in Helsinki. We investigated the contribution of traffic and new particle formation to particles with a diameter between 1 and 800 nm. We found that during spring traffic does not dominate the particles smaller than 3 nm at either of the stations.
Luis M. F. Barreira, Aku Helin, Minna Aurela, Kimmo Teinilä, Milla Friman, Leena Kangas, Jarkko V. Niemi, Harri Portin, Anu Kousa, Liisa Pirjola, Topi Rönkkö, Sanna Saarikoski, and Hilkka Timonen
Atmos. Chem. Phys., 21, 6297–6314, https://doi.org/10.5194/acp-21-6297-2021, https://doi.org/10.5194/acp-21-6297-2021, 2021
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We present results from the long-term measurements (5 years) of highly time-resolved atmospheric PM1 composition at an urban street canyon site. Overall, the results increased knowledge of the variability of PM1 concentration, composition, and sources in a traffic site and the implications for urban air quality. The investigation of pollution episodes showed that both local and long-range-transported pollutants can still cause elevated PM1 and PM2.5 concentrations in northern Europe.
Sami D. Seppälä, Joel Kuula, Antti-Pekka Hyvärinen, Sanna Saarikoski, Topi Rönkkö, Jorma Keskinen, Jukka-Pekka Jalkanen, and Hilkka Timonen
Atmos. Chem. Phys., 21, 3215–3234, https://doi.org/10.5194/acp-21-3215-2021, https://doi.org/10.5194/acp-21-3215-2021, 2021
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The effects of fuel sulfur content restrictions implemented by the International Maritime Organization in the Baltic Sea (in July 2010 and January 2015) on the particle properties of ship exhaust plumes and ambient aerosol were studied. The restrictions reduced the particle number concentrations and median particle size in plumes and number concentrations in ambient aerosol. These changes may improve human health in coastal areas and decrease the cooling effect of exhaust emissions from ships.
Krista Luoma, Jarkko V. Niemi, Minna Aurela, Pak Lun Fung, Aku Helin, Tareq Hussein, Leena Kangas, Anu Kousa, Topi Rönkkö, Hilkka Timonen, Aki Virkkula, and Tuukka Petäjä
Atmos. Chem. Phys., 21, 1173–1189, https://doi.org/10.5194/acp-21-1173-2021, https://doi.org/10.5194/acp-21-1173-2021, 2021
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This study combined black carbon measurements from 15 Finnish sites that represented different environments (traffic, detached housing area, urban background, and regional background). The seasonal and diurnal variations in the black carbon concentration were associated with local emissions from traffic and residential wood burning. The study observed decreasing trends in the black carbon concentration and associated them with decreases in traffic emissions.
Mona Kurppa, Pontus Roldin, Jani Strömberg, Anna Balling, Sasu Karttunen, Heino Kuuluvainen, Jarkko V. Niemi, Liisa Pirjola, Topi Rönkkö, Hilkka Timonen, Antti Hellsten, and Leena Järvi
Geosci. Model Dev., 13, 5663–5685, https://doi.org/10.5194/gmd-13-5663-2020, https://doi.org/10.5194/gmd-13-5663-2020, 2020
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High-resolution modelling is needed to solve the aerosol concentrations in a complex urban area. Here, the performance of an aerosol module within the PALM model to simulate the detailed horizontal and vertical distribution of aerosol particles is studied. Further, sensitivity to the meteorological and aerosol boundary conditions is assessed using both model and observation data. The horizontal distribution is sensitive to the wind speed and stability, and the vertical to the wind direction.
Joel Kuula, Timo Mäkelä, Minna Aurela, Kimmo Teinilä, Samu Varjonen, Óscar González, and Hilkka Timonen
Atmos. Meas. Tech., 13, 2413–2423, https://doi.org/10.5194/amt-13-2413-2020, https://doi.org/10.5194/amt-13-2413-2020, 2020
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Particle-size-dependent detection ranges of low-cost particulate matter sensors were evaluated in a laboratory experiment. Six different sensor models were evaluated altogether. The results showed that none of the sensor models adhered to the technical specifications provided by the manufacturers, and thus a high risk of sensor misuse is posed. It is paramount that the limitations regarding the particle size discrimination of low-cost sensors are acknowledged properly.
Miska Olin, Heino Kuuluvainen, Minna Aurela, Joni Kalliokoski, Niina Kuittinen, Mia Isotalo, Hilkka J. Timonen, Jarkko V. Niemi, Topi Rönkkö, and Miikka Dal Maso
Atmos. Chem. Phys., 20, 1–13, https://doi.org/10.5194/acp-20-1-2020, https://doi.org/10.5194/acp-20-1-2020, 2020
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Photochemically formed sulfuric acid is generally considered the main source for new particle formation in the atmosphere. Contrary to current understanding, our measurements of nanoclusters and gaseous sulfuric acid performed in an urban area imply that traffic contributes to sulfuric acid concentration and that even for the smallest particles, the traffic-emitted fraction mostly exceeds the photochemistry-driven regional new particle formation.
Sanna Saarikoski, Leah R. Williams, Steven R. Spielman, Gregory S. Lewis, Arantzazu Eiguren-Fernandez, Minna Aurela, Susanne V. Hering, Kimmo Teinilä, Philip Croteau, John T. Jayne, Thorsten Hohaus, Douglas R. Worsnop, and Hilkka Timonen
Atmos. Meas. Tech., 12, 3907–3920, https://doi.org/10.5194/amt-12-3907-2019, https://doi.org/10.5194/amt-12-3907-2019, 2019
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An air-to-air ultrafine particle concentrator (Aerosol Dynamics Inc. concentrator; ADIc) has been tailored for the low (~ 0.08 L min−1) inlet flow of aerosol mass spectrometers, and it provides a factor of 8–21 enrichment in the concentration of particles. The ADIc was evaluated in laboratory and field measurements. The results showed that the concentration factor depends primarily on the ratio between the sample flow and the output flow and is independent of particle size above about 10 nm.
Jenni Alanen, Pauli Simonen, Sanna Saarikoski, Hilkka Timonen, Oskari Kangasniemi, Erkka Saukko, Risto Hillamo, Kati Lehtoranta, Timo Murtonen, Hannu Vesala, Jorma Keskinen, and Topi Rönkkö
Atmos. Chem. Phys., 17, 8739–8755, https://doi.org/10.5194/acp-17-8739-2017, https://doi.org/10.5194/acp-17-8739-2017, 2017
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Secondary organic and inorganic aerosols deteriorate air quality. Their formation from a natural gas engine was studied and compared with the emitted primary particulate emission. The volatility of the formed particles was defined as a function of temperature. Photochemical ages 4–11 days, mimicked by a potential aerosol mass chamber, produced 9–20 mg kg−1 fuel SOA. Aged emission particles were found to be less volatile than the fresh, implicating longer stability in the atmosphere.
Hilkka Timonen, Panu Karjalainen, Erkka Saukko, Sanna Saarikoski, Päivi Aakko-Saksa, Pauli Simonen, Timo Murtonen, Miikka Dal Maso, Heino Kuuluvainen, Matthew Bloss, Erik Ahlberg, Birgitta Svenningsson, Joakim Pagels, William H. Brune, Jorma Keskinen, Douglas R. Worsnop, Risto Hillamo, and Topi Rönkkö
Atmos. Chem. Phys., 17, 5311–5329, https://doi.org/10.5194/acp-17-5311-2017, https://doi.org/10.5194/acp-17-5311-2017, 2017
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The effect of fuel ethanol content (10–100 %) on primary emissions and the subsequent secondary aerosol formation was investigated for a Euro 5 flex-fuel gasoline vehicle. The emissions were characterized during the New European Driving Cycle (NEDC) using high time-resolution instruments. The chemical composition of the exhaust particulate matter was studied using a soot particle aerosol mass spectrometer (SP-AMS), and the secondary aerosol formation was studied with an oxidation chamber.
Pauli Simonen, Erkka Saukko, Panu Karjalainen, Hilkka Timonen, Matthew Bloss, Päivi Aakko-Saksa, Topi Rönkkö, Jorma Keskinen, and Miikka Dal Maso
Atmos. Meas. Tech., 10, 1519–1537, https://doi.org/10.5194/amt-10-1519-2017, https://doi.org/10.5194/amt-10-1519-2017, 2017
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Atmospheric particles affect climate, health and visibility, and a large source of these particles is secondary aerosol formation. We developed a new oxidation flow reactor for studying the secondary aerosol formation potential of rapidly changing emission sources. Using laboratory measurements, we show that this flow reactor is suitable for studying the secondary aerosol potential of, for example, light duty vehicle emissions during a transient driving cycle.
Hilkka Timonen, Mike Cubison, Minna Aurela, David Brus, Heikki Lihavainen, Risto Hillamo, Manjula Canagaratna, Bettina Nekat, Rolf Weller, Douglas Worsnop, and Sanna Saarikoski
Atmos. Meas. Tech., 9, 3263–3281, https://doi.org/10.5194/amt-9-3263-2016, https://doi.org/10.5194/amt-9-3263-2016, 2016
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The applicability, methods and limitations of constrained peak fitting on mass spectra of low mass resolving power (m∕Δm50 ∼ 500) recorded with a time-of-flight aerosol chemical speciation monitor (ToF-ACSM) are explored. Calibration measurements and ambient data are used to exemplify the methods that should be applied to maximise data quality and assess confidence in peak-fitting results.
Panu Karjalainen, Hilkka Timonen, Erkka Saukko, Heino Kuuluvainen, Sanna Saarikoski, Päivi Aakko-Saksa, Timo Murtonen, Matthew Bloss, Miikka Dal Maso, Pauli Simonen, Erik Ahlberg, Birgitta Svenningsson, William Henry Brune, Risto Hillamo, Jorma Keskinen, and Topi Rönkkö
Atmos. Chem. Phys., 16, 8559–8570, https://doi.org/10.5194/acp-16-8559-2016, https://doi.org/10.5194/acp-16-8559-2016, 2016
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We characterized time-resolved primary particulate emissions and secondary particle formation from a modern gasoline passenger car. In mass terms, the amount of secondary particles was 13 times the amount of primary particles. The highest emissions were observed after a cold start when the engine and catalyst performance were suboptimal. The key parameter for secondary particle formation was the amount of gaseous hydrocarbons in the exhaust.
S. Carbone, T. Onasch, S. Saarikoski, H. Timonen, K. Saarnio, D. Sueper, T. Rönkkö, L. Pirjola, A. Häyrinen, D. Worsnop, and R. Hillamo
Atmos. Meas. Tech., 8, 4803–4815, https://doi.org/10.5194/amt-8-4803-2015, https://doi.org/10.5194/amt-8-4803-2015, 2015
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The purpose of this study was to develop a method for the quantification of trace metal content in black carbon aerosol in real time, such as combustion-related emissions, by using the SP-AMS. The properties of 13 different trace metals (Na, Al, Ca, V, Cr, Fe, Mn, Ni, Cu, Zn, Rb, Sr and Ba) were investigated in a controlled laboratory experiment. The results from the laboratory tests were applied to study fine particles in emissions of a heavy-fuel-oil-fired heating station.
K. Saarnio, K. Teinilä, S. Saarikoski, S. Carbone, S. Gilardoni, H. Timonen, M. Aurela, and R. Hillamo
Atmos. Meas. Tech., 6, 2839–2849, https://doi.org/10.5194/amt-6-2839-2013, https://doi.org/10.5194/amt-6-2839-2013, 2013
Arya Mukherjee, Anni Hartikainen, Markus Somero, Viljami Luostari, Mika Ihalainen, Christopher P. Rüger, Timo Kekäläinen, Ville H. Nissinen, Luis M. F. Barreira, Hanna Koponen, Tuukka Kokkola, Delun Li, Lejish Vettikkat, Pasi Yli-Pirilä, Muhammad Shahzaib, Meri M. Ruppel, Ville Vakkari, Kerneels Jaars, Stefan J. Siebert, Angela Buchholz, Kajar Köster, Pieter G. van Zyl, Hilkka Timonen, Niko Kinnunen, Janne Jänis, Annele Virtanen, Aki Virkkula, and Olli Sippula
EGUsphere, https://doi.org/10.5194/egusphere-2025-2759, https://doi.org/10.5194/egusphere-2025-2759, 2025
This preprint is open for discussion and under review for Atmospheric Chemistry and Physics (ACP).
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Warming climate is predicted to increase boreal and peatland fires in Northern Eurasia. Limited studies have characterized light absorbing aerosol emissions from these biomasses, thus necessitating this work. Brown carbon (BrC) emitted from laboratory-scale biomass burning had weak light absorptivities based on their complex refractive index values. A combustion temperature dependent light absorptivity continuum existed for emitted BrC. Photochemical aging decreased BrC light absorptivity.
Sami Daniel Harni, Lasse Johansson, Jarkko Ville Niemi, Ville Silvonen, Juan Andrés Casquero-Vera, Anu Kousa, Krista Luoma, Viet Le, David Brus, Konstantinos Doulgeris, Topi Rönkkö, Hanna Manninen, Tuukka Petäjä, and Hilkka Timonen
EGUsphere, https://doi.org/10.5194/egusphere-2025-1423, https://doi.org/10.5194/egusphere-2025-1423, 2025
This preprint is open for discussion and under review for Atmospheric Chemistry and Physics (ACP).
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The 3-month measurement campaign at Espoo, Finland, in spring 2023. The measurement campaign studied the effect of the noise barrier on pollutant concentration gradients on one side of a major highway. The studied pollutants included PM10, PM2.5, lung deposited surface area (LDSA), particle number concentration (PNC), NO2, and black carbon (BC). The noise barrier was found to be effective in reducing, especially the concentration of particulate pollutants.
J. Tapio Elomaa, Krista Luoma, Sami D. Harni, Aki Virkkula, Hilkka Timonen, and Tuukka Petäjä
Aerosol Research, 3, 293–314, https://doi.org/10.5194/ar-3-293-2025, https://doi.org/10.5194/ar-3-293-2025, 2025
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Black carbon (BC) is a pollutant from combustion that affects the climate and is harmful to health. We tested four different small BC sensors with a reference in Helsinki. The sensors compared well with the reference. As a sensor network they were able to capture differences in BC. Changes in temperature (T) and relative humidity (RH) caused error in the measurements. To reduce the effects of T and RH on BC sensors, more robust boxes should be developed, or corrections should be applied.
Fanni Mylläri, Niina Kuittinen, Minna Aurela, Teemu Lepistö, Paavo Heikkilä, Laura Salo, Lassi Markkula, Panu Karjalainen, Joel Kuula, Sami Harni, Katriina Kyllönen, Satu Similä, Katriina Jalkanen, Joakim Autio, Marko Palonen, Jouni Valtatie, Anna Häyrinen, Hilkka Timonen, and Topi Rönkkö
Aerosol Research Discuss., https://doi.org/10.5194/ar-2025-14, https://doi.org/10.5194/ar-2025-14, 2025
Preprint under review for AR
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This study examined particle emissions from a large-scale biomass heating plant. Efficient flue gas cleaning, especially with bag-house filters, significantly reduced primary emissions. However, the potential for secondary aerosol formation was found to be 100–1000 times higher than primary emissions, highlighting the need for further research to support air quality and climate goals.
Kimmo Teinilä, Sanna Saarikoski, Henna Lintusaari, Teemu Lepistö, Petteri Marjanen, Minna Aurela, Heidi Hellén, Toni Tykkä, Markus Lampimäki, Janne Lampilahti, Luis Barreira, Timo Mäkelä, Leena Kangas, Juha Hatakka, Sami Harni, Joel Kuula, Jarkko V. Niemi, Harri Portin, Jaakko Yli-Ojanperä, Ville Niemelä, Milja Jäppi, Katrianne Lehtipalo, Joonas Vanhanen, Liisa Pirjola, Hanna E. Manninen, Tuukka Petäjä, Topi Rönkkö, and Hilkka Timonen
Atmos. Chem. Phys., 25, 4907–4928, https://doi.org/10.5194/acp-25-4907-2025, https://doi.org/10.5194/acp-25-4907-2025, 2025
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Physical and chemical properties of particulate matter and concentrations of trace gases were measured in a street canyon in Helsinki, Finland, and an urban background site in January–February 2022 to investigate the effect of wintertime conditions on pollutants. State-of-the-art instruments and a mobile laboratory were used, and the measurement data were analysed further with modelling tools like positive matrix factorization and the Pollution Detection Algorithm.
Frans Graeffe, Kalle Kupi, Hilkka Timonen, and Mikael Ehn
EGUsphere, https://doi.org/10.5194/egusphere-2025-910, https://doi.org/10.5194/egusphere-2025-910, 2025
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Alkanes are a major part of anthropogenic emissions in urban areas, and known for being capable of producing secondary organic aerosol (SOA). We measured SOA yields of seven alkanes and their oxygenated derivatives in oxidation flow reactor measurements to assess their role in SOA formation. In addition to quantified SOA yields, we observed that cyclic structure enhances SOA production. Furthermore, our observations indicate that multi-generational OH oxidation is important in the SOA formation.
Hector Navarro-Barboza, Jordi Rovira, Vincenzo Obiso, Andrea Pozzer, Marta Via, Andres Alastuey, Xavier Querol, Noemi Perez, Marjan Savadkoohi, Gang Chen, Jesus Yus-Díez, Matic Ivancic, Martin Rigler, Konstantinos Eleftheriadis, Stergios Vratolis, Olga Zografou, Maria Gini, Benjamin Chazeau, Nicolas Marchand, Andre S. H. Prevot, Kaspar Dallenbach, Mikael Ehn, Krista Luoma, Tuukka Petäjä, Anna Tobler, Jaroslaw Necki, Minna Aurela, Hilkka Timonen, Jarkko Niemi, Olivier Favez, Jean-Eudes Petit, Jean-Philippe Putaud, Christoph Hueglin, Nicolas Pascal, Aurélien Chauvigné, Sébastien Conil, Marco Pandolfi, and Oriol Jorba
Atmos. Chem. Phys., 25, 2667–2694, https://doi.org/10.5194/acp-25-2667-2025, https://doi.org/10.5194/acp-25-2667-2025, 2025
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Brown carbon (BrC) absorbs ultraviolet (UV) and visible light, influencing climate. This study explores BrC's imaginary refractive index (k) using data from 12 European sites. Residential emissions are a major organic aerosol (OA) source in winter, while secondary organic aerosol (SOA) dominates in summer. Source-specific k values were derived, improving model accuracy. The findings highlight BrC's climate impact and emphasize source-specific constraints in atmospheric models.
Juho Karhu, Tommi Mikkonen, Joel Kuula, Aki Virkkula, Erkki Ikonen, Markku Vainio, Hilkka Timonen, and Tuomas Hieta
Aerosol Research, 3, 113–124, https://doi.org/10.5194/ar-3-113-2025, https://doi.org/10.5194/ar-3-113-2025, 2025
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We present a new photoacoustic instrument for simultaneous measurement of aerosol light absorption at multiple wavelengths. High performance is reached by using an optically read cantilever microphone, which allows for highly sensitive absorption measurements at a compact size. Performance in field conditions is demonstrated with black carbon monitoring at an air quality measurement station, where our results agree well with reference instruments deployed at the site.
Joel Kuula, Juho Karhu, Tommi Mikkonen, Patrick Grahn, Aki Virkkula, Hilkka Timonen, Tuomas Hieta, and Markku Vainio
Aerosol Research, 3, 1–13, https://doi.org/10.5194/ar-3-1-2025, https://doi.org/10.5194/ar-3-1-2025, 2025
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We developed a new method to measure how particles absorb light as they change in size, which is critical for understanding their climate impact. Our approach uses a sensitive instrument that measures light absorption directly from particles in real time. By pairing this with a device that sorts particles by size, we achieved accurate size-resolved measurements. Our findings closely match theoretical models, offering a promising tool for future research into how particles influence climate.
Sami D. Harni, Minna Aurela, Sanna Saarikoski, Jarkko V. Niemi, Harri Portin, Hanna Manninen, Ville Leinonen, Pasi Aalto, Phil K. Hopke, Tuukka Petäjä, Topi Rönkkö, and Hilkka Timonen
Atmos. Chem. Phys., 24, 12143–12160, https://doi.org/10.5194/acp-24-12143-2024, https://doi.org/10.5194/acp-24-12143-2024, 2024
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In this study, particle number size distribution data were used in a novel way in positive matrix factorization analysis to find aerosol source profiles in the area. Measurements were made in Helsinki at a street canyon and urban background sites between February 2015 and June 2019. Five different aerosol sources were identified. These sources underline the significance of traffic-related emissions in urban environments despite recent improvements in emission reduction technologies.
Teemu Lepistö, Henna Lintusaari, Laura Salo, Ville Silvonen, Luis M. F. Barreira, Jussi Hoivala, Lassi Markkula, Jarkko V. Niemi, Jakub Ondracek, Kimmo Teinilä, Hanna E. Manninen, Sanna Saarikoski, Hilkka Timonen, Miikka Dal Maso, and Topi Rönkkö
Aerosol Research, 2, 271–289, https://doi.org/10.5194/ar-2-271-2024, https://doi.org/10.5194/ar-2-271-2024, 2024
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The performances of different particle lung-deposited surface area (LDSAal) measurement methods (Partector, ELPI+, SMPS/DMPS) were compared in ambient conditions. As LDSAal is a health-relevant metric and rather easy to utilise in air quality monitoring, it is crucial to know how the different methods agree, as there are clear differences in their operation. In all, a comparison of different methods can be complicated; still, the methods agree rather well in terms of local pollution (< 400 nm).
Jian Zhao, Valter Mickwitz, Yuanyuan Luo, Ella Häkkinen, Frans Graeffe, Jiangyi Zhang, Hilkka Timonen, Manjula Canagaratna, Jordan E. Krechmer, Qi Zhang, Markku Kulmala, Juha Kangasluoma, Douglas Worsnop, and Mikael Ehn
Atmos. Meas. Tech., 17, 1527–1543, https://doi.org/10.5194/amt-17-1527-2024, https://doi.org/10.5194/amt-17-1527-2024, 2024
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Organic aerosol constitutes a significant portion of atmospheric fine particles but is less characterized due to its vast number of constituents. Recently, we developed a system for online measurements of particle-phase highly oxygenated organic molecules (HOMs). In this work, we systematically characterized the system, developed a new unit to enhance its performance, and demonstrated the essential role of thermograms in inferring volatility and quantifying HOMs in organic aerosols.
Magdalena Okuljar, Olga Garmash, Miska Olin, Joni Kalliokoski, Hilkka Timonen, Jarkko V. Niemi, Pauli Paasonen, Jenni Kontkanen, Yanjun Zhang, Heidi Hellén, Heino Kuuluvainen, Minna Aurela, Hanna E. Manninen, Mikko Sipilä, Topi Rönkkö, Tuukka Petäjä, Markku Kulmala, Miikka Dal Maso, and Mikael Ehn
Atmos. Chem. Phys., 23, 12965–12983, https://doi.org/10.5194/acp-23-12965-2023, https://doi.org/10.5194/acp-23-12965-2023, 2023
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Highly oxygenated organic molecules (HOMs) form secondary organic aerosol that affects air quality and health. In this study, we demonstrate that in a moderately polluted city with abundant vegetation, the composition of HOMs is largely controlled by the effect of NOx on the biogenic volatile organic compound oxidation. Comparing the results from two nearby stations, we show that HOM composition and formation pathways can change considerably within small distances in urban environments.
Jonas Elm, Aladár Czitrovszky, Andreas Held, Annele Virtanen, Astrid Kiendler-Scharr, Benjamin J. Murray, Daniel McCluskey, Daniele Contini, David Broday, Eirini Goudeli, Hilkka Timonen, Joan Rosell-Llompart, Jose L. Castillo, Evangelia Diapouli, Mar Viana, Maria E. Messing, Markku Kulmala, Naděžda Zíková, and Sebastian H. Schmitt
Aerosol Research, 1, 13–16, https://doi.org/10.5194/ar-1-13-2023, https://doi.org/10.5194/ar-1-13-2023, 2023
Ella Häkkinen, Jian Zhao, Frans Graeffe, Nicolas Fauré, Jordan E. Krechmer, Douglas Worsnop, Hilkka Timonen, Mikael Ehn, and Juha Kangasluoma
Atmos. Meas. Tech., 16, 1705–1721, https://doi.org/10.5194/amt-16-1705-2023, https://doi.org/10.5194/amt-16-1705-2023, 2023
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Highly oxygenated compounds contribute to the formation and growth of atmospheric organic aerosol and thus impact the global climate. Knowledge of their transformations and fate after condensing into the particle phase has been limited by the lack of suitable detection techniques. Here, we present an online method for measuring highly oxygenated compounds from organic aerosol. We evaluate the performance of the method and demonstrate that the method is applicable to different organic species.
Sanna Saarikoski, Heidi Hellén, Arnaud P. Praplan, Simon Schallhart, Petri Clusius, Jarkko V. Niemi, Anu Kousa, Toni Tykkä, Rostislav Kouznetsov, Minna Aurela, Laura Salo, Topi Rönkkö, Luis M. F. Barreira, Liisa Pirjola, and Hilkka Timonen
Atmos. Chem. Phys., 23, 2963–2982, https://doi.org/10.5194/acp-23-2963-2023, https://doi.org/10.5194/acp-23-2963-2023, 2023
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This study elucidates properties and sources of volatile organic compounds (VOCs) and organic aerosol (OA) in a traffic environment. Anthropogenic VOCs (aVOCs) were clearly higher than biogenic VOCs (bVOCs), but bVOCs produced a larger portion of oxidation products. OA consisted mostly of oxygenated OA, representing secondary OA (SOA). SOA was partly associated with bVOCs, but it was also related to long-range transport. Primary OA originated mostly from traffic.
Joel Kuula, Hilkka Timonen, Jarkko V. Niemi, Hanna E. Manninen, Topi Rönkkö, Tareq Hussein, Pak Lun Fung, Sasu Tarkoma, Mikko Laakso, Erkka Saukko, Aino Ovaska, Markku Kulmala, Ari Karppinen, Lasse Johansson, and Tuukka Petäjä
Atmos. Chem. Phys., 22, 4801–4808, https://doi.org/10.5194/acp-22-4801-2022, https://doi.org/10.5194/acp-22-4801-2022, 2022
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Modern and up-to-date policies and air quality management strategies are instrumental in tackling global air pollution. As the European Union is preparing to revise Ambient Air Quality Directive 2008/50/EC, this paper initiates discussion on selected features of the directive that we believe would benefit from a reassessment. The scientific community has the most recent and deepest understanding of air pollution; thus, its contribution is essential.
Pak Lun Fung, Martha A. Zaidan, Jarkko V. Niemi, Erkka Saukko, Hilkka Timonen, Anu Kousa, Joel Kuula, Topi Rönkkö, Ari Karppinen, Sasu Tarkoma, Markku Kulmala, Tuukka Petäjä, and Tareq Hussein
Atmos. Chem. Phys., 22, 1861–1882, https://doi.org/10.5194/acp-22-1861-2022, https://doi.org/10.5194/acp-22-1861-2022, 2022
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We developed an input-adaptive mixed-effects model, which was automatised to select the best combination of input variables, including up to three fixed effect variables and three time indictors as random effect variables. We tested the model to estimate lung-deposited surface area (LDSA), which correlates well with human health. The results show the inclusion of time indicators improved the sensitivity and the accuracy of the model so that it could serve as a network of virtual sensors.
Sanna Saarikoski, Jarkko V. Niemi, Minna Aurela, Liisa Pirjola, Anu Kousa, Topi Rönkkö, and Hilkka Timonen
Atmos. Chem. Phys., 21, 14851–14869, https://doi.org/10.5194/acp-21-14851-2021, https://doi.org/10.5194/acp-21-14851-2021, 2021
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This study presents the main sources of black carbon (BC) at two urban environments. The largest fraction of BC originated from biomass burning at the residential site (38 %) and from vehicular emissions (57 %) in the street canyon. Also, a significant fraction of BC was associated with urban background or long-range transport. The data are needed by modelers and authorities when assessing climate and air quality impact of BC as well as directing the emission legislation and mitigation actions.
Evelyn Freney, Karine Sellegri, Alessia Nicosia, Leah R. Williams, Matteo Rinaldi, Jonathan T. Trueblood, André S. H. Prévôt, Melilotus Thyssen, Gérald Grégori, Nils Haëntjens, Julie Dinasquet, Ingrid Obernosterer, France Van Wambeke, Anja Engel, Birthe Zäncker, Karine Desboeufs, Eija Asmi, Hilkka Timonen, and Cécile Guieu
Atmos. Chem. Phys., 21, 10625–10641, https://doi.org/10.5194/acp-21-10625-2021, https://doi.org/10.5194/acp-21-10625-2021, 2021
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In this work, we present observations of the organic aerosol content in primary sea spray aerosols (SSAs) continuously generated along a 5-week cruise in the Mediterranean. This information is combined with seawater biogeochemical properties also measured continuously along the ship track to develop a number of parametrizations that can be used in models to determine SSA organic content in oligotrophic waters that represent 60 % of the oceans from commonly measured seawater variables.
Magdalena Okuljar, Heino Kuuluvainen, Jenni Kontkanen, Olga Garmash, Miska Olin, Jarkko V. Niemi, Hilkka Timonen, Juha Kangasluoma, Yee Jun Tham, Rima Baalbaki, Mikko Sipilä, Laura Salo, Henna Lintusaari, Harri Portin, Kimmo Teinilä, Minna Aurela, Miikka Dal Maso, Topi Rönkkö, Tuukka Petäjä, and Pauli Paasonen
Atmos. Chem. Phys., 21, 9931–9953, https://doi.org/10.5194/acp-21-9931-2021, https://doi.org/10.5194/acp-21-9931-2021, 2021
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To estimate the relative contribution of different sources to the particle population in an urban environment, we conducted simultaneous measurements at a street canyon and an urban background station in Helsinki. We investigated the contribution of traffic and new particle formation to particles with a diameter between 1 and 800 nm. We found that during spring traffic does not dominate the particles smaller than 3 nm at either of the stations.
Luis M. F. Barreira, Aku Helin, Minna Aurela, Kimmo Teinilä, Milla Friman, Leena Kangas, Jarkko V. Niemi, Harri Portin, Anu Kousa, Liisa Pirjola, Topi Rönkkö, Sanna Saarikoski, and Hilkka Timonen
Atmos. Chem. Phys., 21, 6297–6314, https://doi.org/10.5194/acp-21-6297-2021, https://doi.org/10.5194/acp-21-6297-2021, 2021
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We present results from the long-term measurements (5 years) of highly time-resolved atmospheric PM1 composition at an urban street canyon site. Overall, the results increased knowledge of the variability of PM1 concentration, composition, and sources in a traffic site and the implications for urban air quality. The investigation of pollution episodes showed that both local and long-range-transported pollutants can still cause elevated PM1 and PM2.5 concentrations in northern Europe.
Sami D. Seppälä, Joel Kuula, Antti-Pekka Hyvärinen, Sanna Saarikoski, Topi Rönkkö, Jorma Keskinen, Jukka-Pekka Jalkanen, and Hilkka Timonen
Atmos. Chem. Phys., 21, 3215–3234, https://doi.org/10.5194/acp-21-3215-2021, https://doi.org/10.5194/acp-21-3215-2021, 2021
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The effects of fuel sulfur content restrictions implemented by the International Maritime Organization in the Baltic Sea (in July 2010 and January 2015) on the particle properties of ship exhaust plumes and ambient aerosol were studied. The restrictions reduced the particle number concentrations and median particle size in plumes and number concentrations in ambient aerosol. These changes may improve human health in coastal areas and decrease the cooling effect of exhaust emissions from ships.
Krista Luoma, Jarkko V. Niemi, Minna Aurela, Pak Lun Fung, Aku Helin, Tareq Hussein, Leena Kangas, Anu Kousa, Topi Rönkkö, Hilkka Timonen, Aki Virkkula, and Tuukka Petäjä
Atmos. Chem. Phys., 21, 1173–1189, https://doi.org/10.5194/acp-21-1173-2021, https://doi.org/10.5194/acp-21-1173-2021, 2021
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This study combined black carbon measurements from 15 Finnish sites that represented different environments (traffic, detached housing area, urban background, and regional background). The seasonal and diurnal variations in the black carbon concentration were associated with local emissions from traffic and residential wood burning. The study observed decreasing trends in the black carbon concentration and associated them with decreases in traffic emissions.
Mona Kurppa, Pontus Roldin, Jani Strömberg, Anna Balling, Sasu Karttunen, Heino Kuuluvainen, Jarkko V. Niemi, Liisa Pirjola, Topi Rönkkö, Hilkka Timonen, Antti Hellsten, and Leena Järvi
Geosci. Model Dev., 13, 5663–5685, https://doi.org/10.5194/gmd-13-5663-2020, https://doi.org/10.5194/gmd-13-5663-2020, 2020
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High-resolution modelling is needed to solve the aerosol concentrations in a complex urban area. Here, the performance of an aerosol module within the PALM model to simulate the detailed horizontal and vertical distribution of aerosol particles is studied. Further, sensitivity to the meteorological and aerosol boundary conditions is assessed using both model and observation data. The horizontal distribution is sensitive to the wind speed and stability, and the vertical to the wind direction.
Joel Kuula, Timo Mäkelä, Minna Aurela, Kimmo Teinilä, Samu Varjonen, Óscar González, and Hilkka Timonen
Atmos. Meas. Tech., 13, 2413–2423, https://doi.org/10.5194/amt-13-2413-2020, https://doi.org/10.5194/amt-13-2413-2020, 2020
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Particle-size-dependent detection ranges of low-cost particulate matter sensors were evaluated in a laboratory experiment. Six different sensor models were evaluated altogether. The results showed that none of the sensor models adhered to the technical specifications provided by the manufacturers, and thus a high risk of sensor misuse is posed. It is paramount that the limitations regarding the particle size discrimination of low-cost sensors are acknowledged properly.
Miska Olin, Heino Kuuluvainen, Minna Aurela, Joni Kalliokoski, Niina Kuittinen, Mia Isotalo, Hilkka J. Timonen, Jarkko V. Niemi, Topi Rönkkö, and Miikka Dal Maso
Atmos. Chem. Phys., 20, 1–13, https://doi.org/10.5194/acp-20-1-2020, https://doi.org/10.5194/acp-20-1-2020, 2020
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Photochemically formed sulfuric acid is generally considered the main source for new particle formation in the atmosphere. Contrary to current understanding, our measurements of nanoclusters and gaseous sulfuric acid performed in an urban area imply that traffic contributes to sulfuric acid concentration and that even for the smallest particles, the traffic-emitted fraction mostly exceeds the photochemistry-driven regional new particle formation.
Sanna Saarikoski, Leah R. Williams, Steven R. Spielman, Gregory S. Lewis, Arantzazu Eiguren-Fernandez, Minna Aurela, Susanne V. Hering, Kimmo Teinilä, Philip Croteau, John T. Jayne, Thorsten Hohaus, Douglas R. Worsnop, and Hilkka Timonen
Atmos. Meas. Tech., 12, 3907–3920, https://doi.org/10.5194/amt-12-3907-2019, https://doi.org/10.5194/amt-12-3907-2019, 2019
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An air-to-air ultrafine particle concentrator (Aerosol Dynamics Inc. concentrator; ADIc) has been tailored for the low (~ 0.08 L min−1) inlet flow of aerosol mass spectrometers, and it provides a factor of 8–21 enrichment in the concentration of particles. The ADIc was evaluated in laboratory and field measurements. The results showed that the concentration factor depends primarily on the ratio between the sample flow and the output flow and is independent of particle size above about 10 nm.
Jenni Alanen, Pauli Simonen, Sanna Saarikoski, Hilkka Timonen, Oskari Kangasniemi, Erkka Saukko, Risto Hillamo, Kati Lehtoranta, Timo Murtonen, Hannu Vesala, Jorma Keskinen, and Topi Rönkkö
Atmos. Chem. Phys., 17, 8739–8755, https://doi.org/10.5194/acp-17-8739-2017, https://doi.org/10.5194/acp-17-8739-2017, 2017
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Secondary organic and inorganic aerosols deteriorate air quality. Their formation from a natural gas engine was studied and compared with the emitted primary particulate emission. The volatility of the formed particles was defined as a function of temperature. Photochemical ages 4–11 days, mimicked by a potential aerosol mass chamber, produced 9–20 mg kg−1 fuel SOA. Aged emission particles were found to be less volatile than the fresh, implicating longer stability in the atmosphere.
Hilkka Timonen, Panu Karjalainen, Erkka Saukko, Sanna Saarikoski, Päivi Aakko-Saksa, Pauli Simonen, Timo Murtonen, Miikka Dal Maso, Heino Kuuluvainen, Matthew Bloss, Erik Ahlberg, Birgitta Svenningsson, Joakim Pagels, William H. Brune, Jorma Keskinen, Douglas R. Worsnop, Risto Hillamo, and Topi Rönkkö
Atmos. Chem. Phys., 17, 5311–5329, https://doi.org/10.5194/acp-17-5311-2017, https://doi.org/10.5194/acp-17-5311-2017, 2017
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The effect of fuel ethanol content (10–100 %) on primary emissions and the subsequent secondary aerosol formation was investigated for a Euro 5 flex-fuel gasoline vehicle. The emissions were characterized during the New European Driving Cycle (NEDC) using high time-resolution instruments. The chemical composition of the exhaust particulate matter was studied using a soot particle aerosol mass spectrometer (SP-AMS), and the secondary aerosol formation was studied with an oxidation chamber.
Pauli Simonen, Erkka Saukko, Panu Karjalainen, Hilkka Timonen, Matthew Bloss, Päivi Aakko-Saksa, Topi Rönkkö, Jorma Keskinen, and Miikka Dal Maso
Atmos. Meas. Tech., 10, 1519–1537, https://doi.org/10.5194/amt-10-1519-2017, https://doi.org/10.5194/amt-10-1519-2017, 2017
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Atmospheric particles affect climate, health and visibility, and a large source of these particles is secondary aerosol formation. We developed a new oxidation flow reactor for studying the secondary aerosol formation potential of rapidly changing emission sources. Using laboratory measurements, we show that this flow reactor is suitable for studying the secondary aerosol potential of, for example, light duty vehicle emissions during a transient driving cycle.
Hilkka Timonen, Mike Cubison, Minna Aurela, David Brus, Heikki Lihavainen, Risto Hillamo, Manjula Canagaratna, Bettina Nekat, Rolf Weller, Douglas Worsnop, and Sanna Saarikoski
Atmos. Meas. Tech., 9, 3263–3281, https://doi.org/10.5194/amt-9-3263-2016, https://doi.org/10.5194/amt-9-3263-2016, 2016
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The applicability, methods and limitations of constrained peak fitting on mass spectra of low mass resolving power (m∕Δm50 ∼ 500) recorded with a time-of-flight aerosol chemical speciation monitor (ToF-ACSM) are explored. Calibration measurements and ambient data are used to exemplify the methods that should be applied to maximise data quality and assess confidence in peak-fitting results.
Panu Karjalainen, Hilkka Timonen, Erkka Saukko, Heino Kuuluvainen, Sanna Saarikoski, Päivi Aakko-Saksa, Timo Murtonen, Matthew Bloss, Miikka Dal Maso, Pauli Simonen, Erik Ahlberg, Birgitta Svenningsson, William Henry Brune, Risto Hillamo, Jorma Keskinen, and Topi Rönkkö
Atmos. Chem. Phys., 16, 8559–8570, https://doi.org/10.5194/acp-16-8559-2016, https://doi.org/10.5194/acp-16-8559-2016, 2016
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We characterized time-resolved primary particulate emissions and secondary particle formation from a modern gasoline passenger car. In mass terms, the amount of secondary particles was 13 times the amount of primary particles. The highest emissions were observed after a cold start when the engine and catalyst performance were suboptimal. The key parameter for secondary particle formation was the amount of gaseous hydrocarbons in the exhaust.
S. Carbone, T. Onasch, S. Saarikoski, H. Timonen, K. Saarnio, D. Sueper, T. Rönkkö, L. Pirjola, A. Häyrinen, D. Worsnop, and R. Hillamo
Atmos. Meas. Tech., 8, 4803–4815, https://doi.org/10.5194/amt-8-4803-2015, https://doi.org/10.5194/amt-8-4803-2015, 2015
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The purpose of this study was to develop a method for the quantification of trace metal content in black carbon aerosol in real time, such as combustion-related emissions, by using the SP-AMS. The properties of 13 different trace metals (Na, Al, Ca, V, Cr, Fe, Mn, Ni, Cu, Zn, Rb, Sr and Ba) were investigated in a controlled laboratory experiment. The results from the laboratory tests were applied to study fine particles in emissions of a heavy-fuel-oil-fired heating station.
K. Saarnio, K. Teinilä, S. Saarikoski, S. Carbone, S. Gilardoni, H. Timonen, M. Aurela, and R. Hillamo
Atmos. Meas. Tech., 6, 2839–2849, https://doi.org/10.5194/amt-6-2839-2013, https://doi.org/10.5194/amt-6-2839-2013, 2013
Related subject area
Subject: Gases | Research Activity: Field Measurements | Altitude Range: Troposphere | Science Focus: Chemistry (chemical composition and reactions)
Observation and modeling of atmospheric OH and HO2∗ radicals at a subtropical rural site and implications for secondary pollutants
Tracing elevated abundance of CH2Cl2 in the subarctic upper troposphere to the Asian Summer Monsoon
Carbonyl compounds from typical combustion sources: emission characteristics, influencing factors, and their contribution to ozone formation
Formation drivers and photochemical effects of ClNO2 in a coastal city of Southeast China
Significant influence of oxygenated volatile organic compounds on atmospheric chemistry: a case study in a typical industrial city in China
Global ground-based tropospheric ozone measurements: reference data and individual site trends (2000–2022) from the TOAR-II/HEGIFTOM project
Understanding summertime H2O2 chemistry in the North China Plain through observations and modeling studies
Volatile organic compound sources and impacts in an urban Mediterranean area (Marseille, France)
Short-lived organic nitrates in a suburban temperate forest: an indication of efficient assimilation of reactive nitrogen by the biosphere?
Spatiotemporal variations in atmospheric CH4 concentrations and enhancements in northern China based on a comprehensive dataset: ground-based observations, TROPOMI data, inventory data, and inversions
Marine emissions and trade winds control the atmospheric nitrous oxide in the Galapagos Islands
Measurement report: A complex street-level air quality observation campaign in a heavy-traffic area utilizing the multivariate adaptive regression splines method for field calibration of low-cost sensors
The impact of organic nitrates on summer ozone formation in Shanghai, China
Differences in the key volatile organic compound species between their emitted and ambient concentrations in ozone formation
Tracing Ammonia Emission Sources in California's Salton Sea Region: Insights from Airborne Longwave-Infrared Hyperspectral Imaging and Ground Monitoring
Mechanistic insights into chloroacetic acid production from atmospheric multiphase volatile organic compound–chlorine chemistry
Accurate elucidation of oxidation under heavy ozone pollution: a full suite of radical measurements in the chemically complex atmosphere
Isotopic signatures of methane emission from oil and natural gas plants in southwestern China
Emissions of intermediate-volatility and semi-volatile organic compounds (I/SVOCs) from different cumulative-mileage diesel vehicles at various ambient temperatures
Characterization of nitrous acid and its potential effects on secondary pollution in the warm season in Beijing urban areas
Vertical changes in volatile organic compounds (VOCs) and impacts on photochemical ozone formation
Airborne quantification of Angolan offshore oil and gas methane emissions
Diurnal, seasonal, and interannual variations in δ(18O) of atmospheric O2 and its application to evaluate natural and anthropogenic changes in oxygen, carbon, and water cycles
Cloud processing of dimethyl sulfide (DMS) oxidation products limits sulfur dioxide (SO2) and carbonyl sulfide (OCS) production in the eastern North Atlantic marine boundary layer
Atmospheric carbonyl compounds are crucial in regional ozone heavy pollution: insights from the Chengdu Plain Urban Agglomeration, China
Evaluating urban methane emissions and their attributes in a megacity, Osaka, Japan, via mobile and eddy covariance measurements
Ozone (O3) observations in Saxony, Germany for 1997–2020: Trends, modelling and implications for O3 control
Understanding summertime peroxyacetyl nitrate (PAN) formation and its relation to aerosol pollution: insights from high-resolution measurements and modeling
Measurement report: Exploring the variations in ambient BTEX in urban Europe and their environmental health implications
Seasonal air concentration variability, gas–particle partitioning, precipitation scavenging, and air–water equilibrium of organophosphate esters in southern Canada
Measurement report: Surface exchange fluxes of HONO during the growth process of paddy fields in the Huaihe River Basin, China
Hemispheric differences in ozone across the stratosphere-troposphere exchange region
Molecular and seasonal characteristics of organic vapors in urban Beijing: insights from Vocus-PTR measurements
BVOC and speciated monoterpene concentrations and fluxes at a Scandinavian boreal forest
The variations in volatile organic compounds based on the policy change for Omicron in the traffic hub of Zhengzhou
On the dynamics of ozone depletion events at Villum Research Station in the High Arctic
Measurement report: Long-term measurements of surface ozone and trends in semi-natural sub-Saharan African ecosystems
Characterization of biogenic volatile organic compounds and their oxidation products in a stressed spruce-dominated forest close to a biogas power plant
Reactive chlorine-, sulfur-, and nitrogen-containing volatile organic compounds impact atmospheric chemistry in the megacity of Delhi during both clean and extremely polluted seasons
Analysis of the day-to-day variability of ozone vertical profiles in the lower troposphere during the 2022 Paris ACROSS campaign
Ozone deposition measurements over wheat fields in the North China Plain: variability and related factors of deposition flux and velocity
Consistency evaluation of tropospheric ozone from ozonesonde and IAGOS (In-service Aircraft for a Global Observing System) observations: vertical distribution, ozonesonde types, and station–airport distance
CO2 and CO temporal variability over Mexico City from ground-based total column and surface measurements
Investigating carbonyl compounds above the Amazon rainforest using a proton-transfer-reaction time-of-flight mass spectrometer (PTR-ToF-MS) with NO+ chemical ionization
Measurement report: In-flight and ground-based measurements of nitrogen oxide emissions from latest-generation jet engines and 100 % sustainable aviation fuel
Measurement report: Sources, sinks, and lifetime of NOx in a suburban temperate forest at night
Measurement report: Urban ammonia and amines in Houston, Texas
Biomass-burning sources control ambient particulate matter, but traffic and industrial sources control volatile organic compound (VOC) emissions and secondary-pollutant formation during extreme pollution events in Delhi
Multi-year observations of variable incomplete combustion in the New York megacity
Observations of the vertical distributions of summertime atmospheric pollutants in Nam Co: OH production and source analysis
Zhouxing Zou, Tianshu Chen, Qianjie Chen, Weihang Sun, Shichun Han, Zhuoyue Ren, Xinyi Li, Wei Song, Aoqi Ge, Qi Wang, Xiao Tian, Chenglei Pei, Xinming Wang, Yanli Zhang, and Tao Wang
Atmos. Chem. Phys., 25, 8147–8161, https://doi.org/10.5194/acp-25-8147-2025, https://doi.org/10.5194/acp-25-8147-2025, 2025
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We measured ambient OH and HO2* (HO2 and contribution from RO2, organic peroxyl radicals) concentrations at a subtropical rural site and compared our observations with model results. During warm periods, the model overestimated concentrations of OH and HO2, leading to overestimation of ozone and nitric acid production. Our findings highlight the need to better understand how OH and HO2 are formed and removed, which is important for accurate air quality and climate predictions.
Markus Jesswein, Valentin Lauther, Nicolas Emig, Peter Hoor, Timo Keber, Hans-Christoph Lachnitt, Linda Ort, Tanja Schuck, Johannes Strobel, Ronja Van Luijt, C. Michael Volk, Franziska Weyland, and Andreas Engel
Atmos. Chem. Phys., 25, 8107–8126, https://doi.org/10.5194/acp-25-8107-2025, https://doi.org/10.5194/acp-25-8107-2025, 2025
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The study investigates transport within the Asian Summer Monsoon, focusing on how CH2Cl2 reaches the subarctic tropopause region. Using data from the PHILEAS campaign in 2023, events with increased mixing ratios were detected. Their origin, the transport paths to the tropopause region, and the potential entry into the stratosphere were analyzed. The East Asian Summer Monsoon was identified as the main transport pathway, with only a small contribution to the stratosphere in the following days.
Yanjie Lu, Xinxin Feng, Yanli Feng, Minjun Jiang, Yu Peng, Tian Chen, and Yingjun Chen
Atmos. Chem. Phys., 25, 8043–8059, https://doi.org/10.5194/acp-25-8043-2025, https://doi.org/10.5194/acp-25-8043-2025, 2025
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Through lab tests and field measurements from typical sources, we found that carbonyl compounds from biomass burning are an order of magnitude higher than those from vehicles. The formation of carbonyl compounds in solid and liquid fuel is governed by combustion temperature and emission standards, respectively. Fuel type determines the chemical composition. Biomass burning and farm machinery are key drivers of atmospheric oxidation capacity. This study provides actionable solutions to safeguard public health.
Gaojie Chen, Xiaolong Fan, Haichao Wang, Yee Jun Tham, Ziyi Lin, Xiaoting Ji, Lingling Xu, Baoye Hu, and Jinsheng Chen
Atmos. Chem. Phys., 25, 7815–7828, https://doi.org/10.5194/acp-25-7815-2025, https://doi.org/10.5194/acp-25-7815-2025, 2025
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Our study revealed that the nighttime heterogeneous dinitrogen pentoxide (N2O5) uptake process was the major contributor of nitryl chloride (ClNO2) sources, while nitrate photolysis may promote the elevation of daytime ClNO2 concentrations. The rates of alkane oxidation by chlorine (Cl) radical in the early morning exceeded those by OH radical, significantly promoted the formation of ROx and ozone (O3), and further enhanced the atmospheric oxidation capacity levels.
Jingwen Dai, Kun Zhang, Yanli Feng, Xin Yi, Rui Li, Jin Xue, Qing Li, Lishu Shi, Jiaqiang Liao, Yanan Yi, Fangting Wang, Liumei Yang, Hui Chen, Ling Huang, Jiani Tan, Yangjun Wang, and Li Li
Atmos. Chem. Phys., 25, 7467–7484, https://doi.org/10.5194/acp-25-7467-2025, https://doi.org/10.5194/acp-25-7467-2025, 2025
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Oxygenated volatile organic compounds (OVOCs) are important ozone (O3) precursors. However, most O3 formation analysis based on the box model (OBM) does not include any OVOC constraint. To access the interference of OVOCs with O3 simulation, this study presents results from a field campaign and OBM analysis. Our results indicate that no OVOC constraint in the OBM can lead to overestimation of OVOCs, free radicals, and O3.
Roeland Van Malderen, Anne M. Thompson, Debra E. Kollonige, Ryan M. Stauffer, Herman G. J. Smit, Eliane Maillard Barras, Corinne Vigouroux, Irina Petropavlovskikh, Thierry Leblanc, Valérie Thouret, Pawel Wolff, Peter Effertz, David W. Tarasick, Deniz Poyraz, Gérard Ancellet, Marie-Renée De Backer, Stéphanie Evan, Victoria Flood, Matthias M. Frey, James W. Hannigan, José L. Hernandez, Marco Iarlori, Bryan J. Johnson, Nicholas Jones, Rigel Kivi, Emmanuel Mahieu, Glen McConville, Katrin Müller, Tomoo Nagahama, Justus Notholt, Ankie Piters, Natalia Prats, Richard Querel, Dan Smale, Wolfgang Steinbrecht, Kimberly Strong, and Ralf Sussmann
Atmos. Chem. Phys., 25, 7187–7225, https://doi.org/10.5194/acp-25-7187-2025, https://doi.org/10.5194/acp-25-7187-2025, 2025
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Tropospheric ozone is an important greenhouse gas and is an air pollutant. The time variability of tropospheric ozone is mainly driven by anthropogenic emissions. In this paper, we study the distribution and time variability of ozone from harmonized ground-based observations from five different measurement techniques. Our findings provide clear standard references for atmospheric models and evolving tropospheric ozone satellite data for the 2000–2022 period.
Can Ye, Pengfei Liu, Chaoyang Xue, Chenglong Zhang, Zhuobiao Ma, Chengtang Liu, Junfeng Liu, Keding Lu, Yujing Mu, and Yuanhang Zhang
Atmos. Chem. Phys., 25, 6991–7005, https://doi.org/10.5194/acp-25-6991-2025, https://doi.org/10.5194/acp-25-6991-2025, 2025
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This study investigates H2O2 chemistry in rural North China. The observed H2O2 showed distinct diurnal variations influenced by photochemical reactions. A box model revealed that H2O2 is primarily produced by HO2 recombination and removed mainly via particle uptake. Reductions in NOx, PM2.5, and alkanes raised H2O2 levels, while cutting alkenes, aromatics, CO, and HONO lowered them. A dual strategy focusing on VOC and NOx control is essential to reduce both H2O2 and ozone pollution.
Marvin Dufresne, Thérèse Salameh, Thierry Leonardis, Grégory Gille, Alexandre Armengaud, and Stéphane Sauvage
Atmos. Chem. Phys., 25, 5977–5999, https://doi.org/10.5194/acp-25-5977-2025, https://doi.org/10.5194/acp-25-5977-2025, 2025
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This paper discusses the 18-month-long measurement of non-methane hydrocarbons (NMHCs) in Marseille, where there was no measurement since early 2000, despite the impact of NMHCs on air quality and climate. Traffic-related sources are the largest contributor to NMHC concentrations in Marseille, and shipping strongly contributes to the formation of aerosols. Finally, the Covid-19 lockdown had an impact on NMHC concentrations, reaching a 50 % decrease for traffic-related sources.
Simone T. Andersen, Rolf Sander, Patrick Dewald, Laura Wüst, Tobias Seubert, Gunther N. T. E. Türk, Jan Schuladen, Max R. McGillen, Chaoyang Xue, Abdelwahid Mellouki, Alexandre Kukui, Vincent Michoud, Manuela Cirtog, Mathieu Cazaunau, Astrid Bauville, Hichem Bouzidi, Paola Formenti, Cyrielle Denjean, Jean-Claude Etienne, Olivier Garrouste, Christopher Cantrell, Jos Lelieveld, and John N. Crowley
Atmos. Chem. Phys., 25, 5893–5909, https://doi.org/10.5194/acp-25-5893-2025, https://doi.org/10.5194/acp-25-5893-2025, 2025
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Measurements and modelling of reactive nitrogen gases observed in a suburban temperate forest in Rambouillet, France, circa 50 km southwest of Paris in 2022 indicate that the biosphere rapidly scavenges organic nitrates of mixed biogenic and anthropogenic origin, resulting in short lifetimes for, for example, alkyl nitrates and peroxy nitrates.
Pengfei Han, Ning Zeng, Bo Yao, Wen Zhang, Weijun Quan, Pucai Wang, Ting Wang, Minqiang Zhou, Qixiang Cai, Yuzhong Zhang, Ruosi Liang, Wanqi Sun, and Shengxiang Liu
Atmos. Chem. Phys., 25, 4965–4988, https://doi.org/10.5194/acp-25-4965-2025, https://doi.org/10.5194/acp-25-4965-2025, 2025
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Methane (CH4) is a potent greenhouse gas. Northern China contributes a large proportion of CH4 emissions, yet large observation gaps exist. Here we compiled a comprehensive dataset, which is publicly available, that includes ground-based, satellite-based, inventory, and modeling results to show the CH4 concentrations, enhancements, and spatial–temporal variations. The data can benefit the research community and policy-makers for future observations, atmospheric inversions, and policy-making.
Timur Cinay, Dickon Young, Nazaret Narváez Jimenez, Cristina Vintimilla-Palacios, Ariel Pila Alonso, Paul B. Krummel, William Vizuete, and Andrew R. Babbin
Atmos. Chem. Phys., 25, 4703–4718, https://doi.org/10.5194/acp-25-4703-2025, https://doi.org/10.5194/acp-25-4703-2025, 2025
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We present the initial 15 months of nitrous oxide measurements from the Galapagos Emissions Monitoring Station. The observed variability in atmospheric mole fractions during this period can be linked to several factors: seasonal variations in trade wind speed and direction across the eastern Pacific, differences in the transport history of air masses sampled, and spatiotemporal heterogeneity in regional marine nitrous oxide emissions from the coastal upwelling systems of Peru and Chile.
Petra Bauerová, Josef Keder, Adriana Šindelářová, Ondřej Vlček, William Patiño, Pavel Krč, Jan Geletič, Hynek Řezníček, Martin Bureš, Kryštof Eben, Michal Belda, Jelena Radović, Vladimír Fuka, Radek Jareš, Igor Esau, and Jaroslav Resler
Atmos. Chem. Phys., 25, 4477–4504, https://doi.org/10.5194/acp-25-4477-2025, https://doi.org/10.5194/acp-25-4477-2025, 2025
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The study explored urban air quality in Prague using low-cost sensors and highlighted the multivariate adaptive regression splines (MARS) correction method's effectiveness in enhancing accuracy. Results showed traffic's impact on nitrogen dioxide levels and atmospheric dynamics on particulate matter. The research confirmed MARS-corrected sensors as cost-effective for monitoring, despite challenges like sensor ageing and data quality control.
Chunmeng Li, Xiaorui Chen, Haichao Wang, Tianyu Zhai, Xuefei Ma, Xinping Yang, Shiyi Chen, Min Zhou, Shengrong Lou, Xin Li, Limin Zeng, and Keding Lu
Atmos. Chem. Phys., 25, 3905–3918, https://doi.org/10.5194/acp-25-3905-2025, https://doi.org/10.5194/acp-25-3905-2025, 2025
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This study reports an observation of organic nitrate (including total peroxy nitrates and total alkyl nitrates) in Shanghai, China, during the summer of 2021, by homemade thermal dissociation cavity-enhanced absorption spectroscopy (TD-CEAS; Atmos. Meas. Tech., 14, 4033–4051, 2021). The distribution of organic nitrates and their effects on local ozone production are analyzed based on field observations in conjunction with model simulations.
Xudong Zheng and Shaodong Xie
Atmos. Chem. Phys., 25, 3807–3820, https://doi.org/10.5194/acp-25-3807-2025, https://doi.org/10.5194/acp-25-3807-2025, 2025
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To reduce uncertainties in identifying the key volatile organic compounds (VOCs) in ozone (O3) formation from ambient concentrations, this study comprehensively calculates the emitted VOC concentrations during both nighttime and daytime using the nitrate radical, O3, and hydroxyl radical reaction rates and ambient VOC concentrations. Based on the emitted concentrations, isoprene is one of the top three species contributing to O3 formation, which may be overlooked in observed concentrations.
Sina Hasheminassab, David M. Tratt, Olga V. Kalashnikova, Clement S. Chang, Morad Alvarez, Kerry N. Buckland, Michael J. Garay, Francesca M. Hopkins, Eric R. Keim, Le Kuai, Yaning Miao, Payam Pakbin, William C. Porter, and Mohammad H. Sowlat
EGUsphere, https://doi.org/10.5194/egusphere-2025-1378, https://doi.org/10.5194/egusphere-2025-1378, 2025
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Ammonia (NH3) is a key air pollutant linked to fine particle pollution, yet its sources remain poorly understood. Using airborne infrared imaging and ground sensors, we mapped NH3 emissions in California’s Salton Sea region with unprecedented detail. We found high emissions from farms, geothermal plants, and waste sites, including sources missing from inventories. These findings highlight the need for better NH3 monitoring to improve air quality models and guide pollution reduction strategies.
Mingxue Li, Men Xia, Chunshui Lin, Yifan Jiang, Weihang Sun, Yurun Wang, Yingnan Zhang, Maoxia He, and Tao Wang
Atmos. Chem. Phys., 25, 3753–3764, https://doi.org/10.5194/acp-25-3753-2025, https://doi.org/10.5194/acp-25-3753-2025, 2025
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Our field campaigns observed a strong diel pattern of chloroacetic acid as well as a strong correlation between its level and that of reactive chlorine species at a coastal site. Using quantum chemical calculations and box model simulation with an updated Master Chemical Mechanism, we found that the formation pathway of chloroacetic acid involved multiphase processes. Our study enhances understanding of atmospheric organic chlorine chemistry and emphasizes the importance of multiphase reactions.
Renzhi Hu, Guoxian Zhang, Haotian Cai, Jingyi Guo, Keding Lu, Xin Li, Shengrong Lou, Zhaofeng Tan, Changjin Hu, Pinhua Xie, and Wenqing Liu
Atmos. Chem. Phys., 25, 3011–3028, https://doi.org/10.5194/acp-25-3011-2025, https://doi.org/10.5194/acp-25-3011-2025, 2025
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A full suite of radical measurements (OH, HO2, RO2, and kOH) was established to accurately elucidate the limitations of oxidation in a chemically complex atmosphere. Sensitivity tests revealed that the incorporation of complex processes enabled a balance in both radical concentrations and coordinate ratios, effectively addressing the deficiency in the ozone generation mechanism. The full-chain radical detection bridged the gap between the photochemistry and the intensive oxidation level.
Dingxi Chen, Yi Liu, Zetong Niu, Ao Wang, Pius Otwil, Yuanyuan Huang, Zhongcong Sun, Xiaobing Pang, Liyang Zhan, and Longfei Yu
EGUsphere, https://doi.org/10.5194/egusphere-2025-377, https://doi.org/10.5194/egusphere-2025-377, 2025
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We carried out studies at 11 oil and gas sites in Southwest China (an important natural gas production area), investigating the methane concentration distribution pattern and emission inventory of oil and gas industrial sites through a combination of ground monitoring and drone airborne monitoring techniques, and at the same time, utilizing stable isotope techniques to trace back the methane from the oil and gas sites.
Shuwen Guo, Xuan Zheng, Xiao He, Lewei Zeng, Liqiang He, Xian Wu, Yifei Dai, Zihao Huang, Ting Chen, Shupei Xiao, Yan You, Sheng Xiang, Shaojun Zhang, Jingkun Jiang, and Ye Wu
Atmos. Chem. Phys., 25, 2695–2705, https://doi.org/10.5194/acp-25-2695-2025, https://doi.org/10.5194/acp-25-2695-2025, 2025
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We considered two potential influencing factors of heavy-duty diesel vehicle emissions that are rarely mentioned in the literature: cumulative mileage and ambient temperatures. The results suggest that prolonged use of heavy-duty diesel vehicles and low ambient temperatures leads to reduced engine combustion efficiency, which in turn increases tailpipe emissions significantly.
Junling Li, Chaofan Lian, Mingyuan Liu, Hao Zhang, Yongxin Yan, Yufei Song, Chun Chen, Jiaqi Wang, Haijie Zhang, Yanqin Ren, Yucong Guo, Weigang Wang, Yisheng Xu, Hong Li, Jian Gao, and Maofa Ge
Atmos. Chem. Phys., 25, 2551–2568, https://doi.org/10.5194/acp-25-2551-2025, https://doi.org/10.5194/acp-25-2551-2025, 2025
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As a key source of hydroxyl (OH) radical, nitrous acid (HONO) has attracted much attention for its important role in the atmospheric oxidant capacity (AOC) increase. In this study, we made a comparison of the ambient levels, variation patterns, sources, and formation pathway in the warm season on the basis of continuous intensive observations at an urban site of Beijing. This work highlights the importance of HONO for the AOC in the warm season.
Xiao-Bing Li, Bin Yuan, Yibo Huangfu, Suxia Yang, Xin Song, Jipeng Qi, Xianjun He, Sihang Wang, Yubin Chen, Qing Yang, Yongxin Song, Yuwen Peng, Guiqian Tang, Jian Gao, Dasa Gu, and Min Shao
Atmos. Chem. Phys., 25, 2459–2472, https://doi.org/10.5194/acp-25-2459-2025, https://doi.org/10.5194/acp-25-2459-2025, 2025
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Online vertical gradient measurements of volatile organic compounds (VOCs), ozone, and NOx were conducted based on a 325 m tall tower in urban Beijing. Vertical changes in the concentrations, compositions, key drivers, and environmental impacts of VOCs were analyzed in this study. We find that VOC species display differentiated vertical variation patterns and distinct roles in contributing to photochemical ozone formation with increasing height in the urban planetary boundary layer.
Alina Fiehn, Maximilian Eckl, Magdalena Pühl, Tiziana Bräuer, Klaus-Dirk Gottschaldt, Heinfried Aufmhoff, Lisa Eirenschmalz, Gregor Neumann, Felicitas Sakellariou, Daniel Sauer, Robert Baumann, Guilherme De Aguiar Ventura, Winne Nayole Cadete, Dário Luciano Zua, Manuel Xavier, Paulo Correia, and Anke Roiger
EGUsphere, https://doi.org/10.5194/egusphere-2025-635, https://doi.org/10.5194/egusphere-2025-635, 2025
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In September 2022, the METHANE-To-Go Africa (MTGA) campaign, part of UNEP’s IMEO Methane Science Studies, conducted the first CH₄ emissions measurements from West Africa’s offshore oil and gas sector. Using an aircraft-based mass balance method, emissions from Angolan offshore facilities were quantified. Older, low-producing facilities showed higher emissions than newer ones. High-emission events were observed, highlighting the need for targeted monitoring and mitigation efforts.
Shigeyuki Ishidoya, Satoshi Sugawara, and Atsushi Okazaki
Atmos. Chem. Phys., 25, 1965–1987, https://doi.org/10.5194/acp-25-1965-2025, https://doi.org/10.5194/acp-25-1965-2025, 2025
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The 18O/16O ratio of atmospheric oxygen, δatm(18O), is higher than that of ocean water due to isotopic effects during biospheric activities. This is known as the Dole–Morita effect, and its millennial-scale variations are recorded in ice cores. However, small variations of δatm(18O) in the present day have never been detected so far. This paper presents the first observations of diurnal, seasonal, and secular variations in δatm(18O) and applies them to evaluate oxygen, carbon, and water cycles.
Delaney B. Kilgour, Christopher M. Jernigan, Olga Garmash, Sneha Aggarwal, Shengqian Zhou, Claudia Mohr, Matt E. Salter, Joel A. Thornton, Jian Wang, Paul Zieger, and Timothy H. Bertram
Atmos. Chem. Phys., 25, 1931–1947, https://doi.org/10.5194/acp-25-1931-2025, https://doi.org/10.5194/acp-25-1931-2025, 2025
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We report simultaneous measurements of dimethyl sulfide (DMS) and hydroperoxymethyl thioformate (HPMTF) in the eastern North Atlantic. We use an observationally constrained box model to show that cloud loss is the dominant sink of HPMTF in this region over 6 weeks, resulting in large reductions in DMS-derived products that contribute to aerosol formation and growth. Our findings indicate that fast cloud processing of HPMTF must be included in global models to accurately capture the sulfur cycle.
Jiemeng Bao, Xin Zhang, Zhenhai Wu, Li Zhou, Jun Qian, Qinwen Tan, Fumo Yang, Junhui Chen, Yunfeng Li, Hefan Liu, Liqun Deng, and Hong Li
Atmos. Chem. Phys., 25, 1899–1916, https://doi.org/10.5194/acp-25-1899-2025, https://doi.org/10.5194/acp-25-1899-2025, 2025
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We studied carbonyl compounds' role in ozone pollution in the Chengdu Plain Urban Agglomeration, China. During heavy pollution in August 2019, we measured carbonyls at nine sites and analyzed their impact. Areas with higher carbonyl levels, like Chengdu, had worse ozone pollution. While their abundance matters, chemical reactions with other pollutants are the main drivers. Our findings show regional cooperation is vital to reducing ozone pollution effectively.
Masahito Ueyama, Taku Umezawa, Yukio Terao, Mark Lunt, and James Lawrence France
EGUsphere, https://doi.org/10.5194/egusphere-2024-3926, https://doi.org/10.5194/egusphere-2024-3926, 2025
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Methane (CH4) emissions were measured in Megacity Osaka, Japan, using mobile and eddy covariance methods. The CH4 emissions were much higher than those reported in local inventories, with natural gas contributing up to 74 % of the emissions. Several CH4 sources not accounted for in current inventories were identified. These results emphasize the need for more comprehensive emissions tracking in urban areas to enhance climate change mitigation efforts.
Yaru Wang, Dominik van Pinxteren, Andreas Tilgner, Erik Hans Hoffmann, Max Hell, Susanne Bastian, and Hartmut Herrmann
EGUsphere, https://doi.org/10.5194/egusphere-2024-4202, https://doi.org/10.5194/egusphere-2024-4202, 2025
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Tropospheric ground-level ozone (O3) is a global air-quality pollutant and greenhouse gas. Long-term O3 trends from 16 stations in Saxony, Germany, were compared over three periods, revealing worsened O3 pollution over the last decade. O3 formation has been volatile organic compound (VOC)-limited at traffic and urban sites for the past 20 years. To mitigate O3 pollution, moderate nitrogen oxides and additional VOC controls, particularly in solvent use, should be prioritized in the coming years.
Baoye Hu, Naihua Chen, Rui Li, Mingqiang Huang, Jinsheng Chen, Youwei Hong, Lingling Xu, Xiaolong Fan, Mengren Li, Lei Tong, Qiuping Zheng, and Yuxiang Yang
Atmos. Chem. Phys., 25, 905–921, https://doi.org/10.5194/acp-25-905-2025, https://doi.org/10.5194/acp-25-905-2025, 2025
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Box modeling with the Master Chemical Mechanism (MCM) was used to explore summertime peroxyacetyl nitrate (PAN) formation and its link to aerosol pollution under high-ozone conditions. The MCM model is effective in the study of PAN photochemical formation and performed better during the clean period than the haze period. Machine learning analysis identified ammonia, nitrate, and fine particulate matter as the top three factors contributing to simulation bias.
Xiansheng Liu, Xun Zhang, Marvin Dufresne, Tao Wang, Lijie Wu, Rosa Lara, Roger Seco, Marta Monge, Ana Maria Yáñez-Serrano, Marie Gohy, Paul Petit, Audrey Chevalier, Marie-Pierre Vagnot, Yann Fortier, Alexia Baudic, Véronique Ghersi, Grégory Gille, Ludovic Lanzi, Valérie Gros, Leïla Simon, Heidi Héllen, Stefan Reimann, Zoé Le Bras, Michelle Jessy Müller, David Beddows, Siqi Hou, Zongbo Shi, Roy M. Harrison, William Bloss, James Dernie, Stéphane Sauvage, Philip K. Hopke, Xiaoli Duan, Taicheng An, Alastair C. Lewis, James R. Hopkins, Eleni Liakakou, Nikolaos Mihalopoulos, Xiaohu Zhang, Andrés Alastuey, Xavier Querol, and Thérèse Salameh
Atmos. Chem. Phys., 25, 625–638, https://doi.org/10.5194/acp-25-625-2025, https://doi.org/10.5194/acp-25-625-2025, 2025
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This study examines BTEX (benzene, toluene, ethylbenzene, xylenes) pollution in urban areas across seven European countries. Analyzing data from 22 monitoring sites, we found traffic and industrial activities significantly impact BTEX levels, with peaks during rush hours. The risk from BTEX exposure remains moderate, especially in high-traffic and industrial zones, highlighting the need for targeted air quality management to protect public health and improve urban air quality.
Yuening Li, Faqiang Zhan, Chubashini Shunthirasingham, Ying Duan Lei, Jenny Oh, Amina Ben Chaaben, Zhe Lu, Kelsey Lee, Frank A. P. C. Gobas, Hayley Hung, and Frank Wania
Atmos. Chem. Phys., 25, 459–472, https://doi.org/10.5194/acp-25-459-2025, https://doi.org/10.5194/acp-25-459-2025, 2025
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Organophosphate esters are important humanmade trace contaminants. Measuring them in the atmospheric gas phase, particles, precipitation, and surface water in Canada, we explore seasonal concentration variability, gas–particle partitioning, precipitation scavenging, and the air–water equilibrium. Whereas higher summer concentrations and efficient precipitation scavenging conform with expectations, the lack of a relationship between compound volatility and gas–particle partitioning is puzzling.
Fanhao Meng, Baobin Han, Min Qin, Wu Fang, Ke Tang, Dou Shao, Zhitang Liao, Jun Duan, Yan Feng, Yong Huang, Ting Ni, and Pinhua Xie
Atmos. Chem. Phys., 24, 14191–14208, https://doi.org/10.5194/acp-24-14191-2024, https://doi.org/10.5194/acp-24-14191-2024, 2024
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Comprehensive observations of HONO and NOx fluxes were conducted over paddy fields in the Huaihe River Basin. Consecutive peaks in HONO and NO fluxes suggest a potentially enhanced release of HONO and NO due to soil tillage, whereas waterlogged soil may inhibit microbial nitrification processes following irrigation. Notably, biological processes and light-driven NO2 reactions at the surface may serve as sources of HONO and influence the local HONO budget during rotary tillage.
Rodrigo J. Seguel, Charlie Opazo, Yann Cohen, Owen R. Cooper, Laura Gallardo, Björn-Martin Sinnhuber, Florian Obersteiner, Andreas Zahn, Peter Hoor, and Susanne Rohs
EGUsphere, https://doi.org/10.5194/egusphere-2024-3719, https://doi.org/10.5194/egusphere-2024-3719, 2024
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We explored differences in ozone levels between the Northern and Southern Hemispheres in the Stratosphere-troposphere exchange region. Using unique data from a research aircraft, we found significantly lower ozone levels (with stratospheric character) in the Southern Hemisphere, especially during years of severe ozone depletion. A Sudden Stratospheric Warming event in 2019 increased Southern Hemisphere ozone levels, highlighting the relationship between atmospheric events and ozone distribution.
Zhaojin An, Rujing Yin, Xinyan Zhao, Xiaoxiao Li, Yuyang Li, Yi Yuan, Junchen Guo, Yiqi Zhao, Xue Li, Dandan Li, Yaowei Li, Dongbin Wang, Chao Yan, Kebin He, Douglas R. Worsnop, Frank N. Keutsch, and Jingkun Jiang
Atmos. Chem. Phys., 24, 13793–13810, https://doi.org/10.5194/acp-24-13793-2024, https://doi.org/10.5194/acp-24-13793-2024, 2024
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Online Vocus-PTR measurements show the compositions and seasonal variations in organic vapors in urban Beijing. With enhanced sensitivity and mass resolution, various species at a level of sub-parts per trillion (ppt) and organics with multiple oxygens (≥ 3) were observed. The fast photooxidation process in summer leads to an increase in both concentration and proportion of organics with multiple oxygens, while, in other seasons, the variations in them could be influenced by mixed sources.
Ross Charles Petersen, Thomas Holst, Cheng Wu, Radovan Krejci, Jeremy Chan, Claudia Mohr, and Janne Rinne
EGUsphere, https://doi.org/10.5194/egusphere-2024-3410, https://doi.org/10.5194/egusphere-2024-3410, 2024
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Ecosystem-scale emissions of biogenic volatile organic compounds (BVOCs) are important for atmospheric chemistry. Here we investigate boreal BVOC fluxes from a forest in central Sweden. BVOC fluxes were measured above-canopy using proton-transfer-reaction mass spectrometry, while compound-specific monoterpene (MT) fluxes were assessed using a concentration gradient method. We also evaluate the impact of chemical degradation on observed sesquiterpene (SQT) and nighttime MT fluxes.
Bowen Zhang, Dong Zhang, Zhe Dong, Xinshuai Song, Ruiqin Zhang, and Xiao Li
Atmos. Chem. Phys., 24, 13587–13601, https://doi.org/10.5194/acp-24-13587-2024, https://doi.org/10.5194/acp-24-13587-2024, 2024
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To gain insight into the impact of changes due to epidemic control policies, we undertook continuous online monitoring of volatile organic compounds (VOCs) at an urban site in Zhengzhou over a 2-month period. This study examines the characteristics of VOCs, their sources, and their temporal evolution. It also assesses the impact of the policy change on VOC pollution during the monitoring period, thus providing a basis for further research on VOC pollution and source control.
Jakob Boyd Pernov, Jens Liengaard Hjorth, Lise Lotte Sørensen, and Henrik Skov
Atmos. Chem. Phys., 24, 13603–13631, https://doi.org/10.5194/acp-24-13603-2024, https://doi.org/10.5194/acp-24-13603-2024, 2024
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Arctic ozone depletion events (ODEs) occur every spring and have vast implications for the oxidizing capacity, radiative balance, and mercury oxidation. In this study, we analyze ozone, ODEs, and their connection to meteorological and air mass history variables through statistical analyses, back trajectories, and machine learning (ML) at Villum Research Station. ODEs are favorable under sunny, calm conditions with air masses arriving from northerly wind directions with sea ice contact.
Hagninou Elagnon Venance Donnou, Aristide Barthélémy Akpo, Money Ossohou, Claire Delon, Véronique Yoboué, Dungall Laouali, Marie Ouafo-Leumbe, Pieter Gideon Van Zyl, Ousmane Ndiaye, Eric Gardrat, Maria Dias-Alves, and Corinne Galy-Lacaux
Atmos. Chem. Phys., 24, 13151–13182, https://doi.org/10.5194/acp-24-13151-2024, https://doi.org/10.5194/acp-24-13151-2024, 2024
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Ozone is a secondary air pollutant that is detrimental to human and plant health. A better understanding of its chemical evolution is a challenge for Africa, where it is still undersampled. Out of 14 sites examined (1995–2020), high levels of O3 are reported in southern Africa. The dominant chemical processes leading to O3 formation are identified. A decrease in O3 is observed at Katibougou (Mali) and Banizoumbou (Niger), and an increase is found at Zoétélé (Cameroon) and Skukuza (South Africa).
Junwei Song, Georgios I. Gkatzelis, Ralf Tillmann, Nicolas Brüggemann, Thomas Leisner, and Harald Saathoff
Atmos. Chem. Phys., 24, 13199–13217, https://doi.org/10.5194/acp-24-13199-2024, https://doi.org/10.5194/acp-24-13199-2024, 2024
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Biogenic volatile organic compounds (BVOCs) and organic aerosol (OA) particles were measured online in a stressed spruce-dominated forest. OA was mainly attributed to the monoterpene oxidation products. The mixing ratios of BVOCs were higher than the values previously measured in other temperate forests. The results demonstrate that BVOCs are influenced not only by meteorology and biogenic emissions but also by local anthropogenic emissions and subsequent chemical transformation processes.
Sachin Mishra, Vinayak Sinha, Haseeb Hakkim, Arpit Awasthi, Sachin D. Ghude, Vijay Kumar Soni, Narendra Nigam, Baerbel Sinha, and Madhavan N. Rajeevan
Atmos. Chem. Phys., 24, 13129–13150, https://doi.org/10.5194/acp-24-13129-2024, https://doi.org/10.5194/acp-24-13129-2024, 2024
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We quantified 111 gases using mass spectrometry to understand how seasonal and emission changes lead from clean air in the monsoon season to extremely polluted air in the post-monsoon season in Delhi. Averaged total mass concentrations (260 µg m-3) were > 4 times in polluted periods, driven by biomass burning emissions and reduced atmospheric ventilation. Reactive gaseous nitrogen, chlorine, and sulfur compounds hitherto unreported from such a polluted environment were discovered.
Gérard Ancellet, Camille Viatte, Anne Boynard, François Ravetta, Jacques Pelon, Cristelle Cailteau-Fischbach, Pascal Genau, Julie Capo, Axel Roy, and Philippe Nédélec
Atmos. Chem. Phys., 24, 12963–12983, https://doi.org/10.5194/acp-24-12963-2024, https://doi.org/10.5194/acp-24-12963-2024, 2024
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Characterization of ozone pollution in urban areas benefited from a measurement campaign in summer 2022 in the Paris region. The analysis is based on 21 d of lidar and aircraft observations. The main objective is an analysis of the sensitivity of ozone pollution to the micrometeorological processes in the urban atmospheric boundary layer and the transport of regional pollution. The paper also discusses to what extent satellite observations can track observed ozone plumes.
Xiaoyi Zhang, Wanyun Xu, Weili Lin, Gen Zhang, Jinjian Geng, Li Zhou, Huarong Zhao, Sanxue Ren, Guangsheng Zhou, Jianmin Chen, and Xiaobin Xu
Atmos. Chem. Phys., 24, 12323–12340, https://doi.org/10.5194/acp-24-12323-2024, https://doi.org/10.5194/acp-24-12323-2024, 2024
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Ozone (O3) deposition is a key process that removes surface O3, affecting air quality, ecosystems and climate change. We conducted O3 deposition measurement over a wheat canopy using a newly relaxed eddy accumulation flux system. Large variabilities in O3 deposition were detected, mainly determined by crop growth and modulated by various environmental factors. More O3 deposition observations over different surfaces are needed for exploring deposition mechanisms and model optimization.
Honglei Wang, David W. Tarasick, Jane Liu, Herman G. J. Smit, Roeland Van Malderen, Lijuan Shen, Romain Blot, and Tianliang Zhao
Atmos. Chem. Phys., 24, 11927–11942, https://doi.org/10.5194/acp-24-11927-2024, https://doi.org/10.5194/acp-24-11927-2024, 2024
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In this study, we identify 23 suitable pairs of sites from World Ozone and Ultraviolet Radiation Data Centre (WOUDC) and In-service Aircraft for a Global Observing System (IAGOS) datasets (1995 to 2021), compare the average vertical distributions of tropospheric O3 from ozonesonde and aircraft measurements, and analyze the differences based on ozonesonde type and station–airport distance.
Noémie Taquet, Wolfgang Stremme, María Eugenia González del Castillo, Victor Almanza, Alejandro Bezanilla, Olivier Laurent, Carlos Alberti, Frank Hase, Michel Ramonet, Thomas Lauvaux, Ke Che, and Michel Grutter
Atmos. Chem. Phys., 24, 11823–11848, https://doi.org/10.5194/acp-24-11823-2024, https://doi.org/10.5194/acp-24-11823-2024, 2024
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We characterize the variability in CO and CO2 emissions over Mexico City from long-term time-resolved Fourier transform infrared spectroscopy solar absorption and surface measurements from 2013 to 2021. Using the average intraday CO growth rate from total columns, the average CO / CO2 ratio and TROPOMI data, we estimate the interannual variability in the CO and CO2 anthropogenic emissions of Mexico City, highlighting the effect of an unprecedented drop in activity due to the COVID-19 lockdown.
Akima Ringsdorf, Achim Edtbauer, Bruna Holanda, Christopher Poehlker, Marta O. Sá, Alessandro Araújo, Jürgen Kesselmeier, Jos Lelieveld, and Jonathan Williams
Atmos. Chem. Phys., 24, 11883–11910, https://doi.org/10.5194/acp-24-11883-2024, https://doi.org/10.5194/acp-24-11883-2024, 2024
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We show the average height distribution of separately observed aldehydes and ketones over a day and discuss their rainforest-specific sources and sinks as well as their seasonal changes above the Amazon. Ketones have much longer atmospheric lifetimes than aldehydes and thus different implications for atmospheric chemistry. However, they are commonly observed together, which we overcome by measuring with a NO+ chemical ionization mass spectrometer for the first time in the Amazon rainforest.
Theresa Harlass, Rebecca Dischl, Stefan Kaufmann, Raphael Märkl, Daniel Sauer, Monika Scheibe, Paul Stock, Tiziana Bräuer, Andreas Dörnbrack, Anke Roiger, Hans Schlager, Ulrich Schumann, Magdalena Pühl, Tobias Schripp, Tobias Grein, Linda Bondorf, Charles Renard, Maxime Gauthier, Mark Johnson, Darren Luff, Paul Madden, Peter Swann, Denise Ahrens, Reetu Sallinen, and Christiane Voigt
Atmos. Chem. Phys., 24, 11807–11822, https://doi.org/10.5194/acp-24-11807-2024, https://doi.org/10.5194/acp-24-11807-2024, 2024
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Emissions from aircraft have a direct impact on our climate. Here, we present airborne and ground-based measurement data of nitrogen oxides that were collected in the exhaust of an Airbus aircraft. We study the impact of burning fossil and sustainable aviation fuel on nitrogen oxide emissions at different engine settings related to combustor temperature, pressure and fuel flow. Further, we compare observations with engine emission models.
Simone T. Andersen, Max R. McGillen, Chaoyang Xue, Tobias Seubert, Patrick Dewald, Gunther N. T. E. Türk, Jan Schuladen, Cyrielle Denjean, Jean-Claude Etienne, Olivier Garrouste, Marina Jamar, Sergio Harb, Manuela Cirtog, Vincent Michoud, Mathieu Cazaunau, Antonin Bergé, Christopher Cantrell, Sebastien Dusanter, Bénédicte Picquet-Varrault, Alexandre Kukui, Abdelwahid Mellouki, Lucy J. Carpenter, Jos Lelieveld, and John N. Crowley
Atmos. Chem. Phys., 24, 11603–11618, https://doi.org/10.5194/acp-24-11603-2024, https://doi.org/10.5194/acp-24-11603-2024, 2024
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Using measurements of various trace gases in a suburban forest near Paris in the summer of 2022, we were able to gain insight into the sources and sinks of NOx (NO+NO2) with a special focus on their nighttime chemical and physical loss processes. NO was observed as a result of nighttime soil emissions when O3 levels were strongly depleted by deposition. NO oxidation products were not observed at night, indicating that soil and/or foliar surfaces are an efficient sink of reactive N.
Lee Tiszenkel, James H. Flynn, and Shan-Hu Lee
Atmos. Chem. Phys., 24, 11351–11363, https://doi.org/10.5194/acp-24-11351-2024, https://doi.org/10.5194/acp-24-11351-2024, 2024
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Ammonia and amines are important ingredients for aerosol formation in urban environments, but the measurements of these compounds are extremely challenging. Our observations show that urban ammonia and amines in Houston are emitted from urban sources, and diurnal variations in their concentrations are likely governed by gas-to-particle conversion and emissions.
Arpit Awasthi, Baerbel Sinha, Haseeb Hakkim, Sachin Mishra, Varkrishna Mummidivarapu, Gurmanjot Singh, Sachin D. Ghude, Vijay Kumar Soni, Narendra Nigam, Vinayak Sinha, and Madhavan N. Rajeevan
Atmos. Chem. Phys., 24, 10279–10304, https://doi.org/10.5194/acp-24-10279-2024, https://doi.org/10.5194/acp-24-10279-2024, 2024
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We use 111 volatile organic compounds (VOCs), PM10, and PM2.5 in a positive matrix factorization (PMF) model to resolve 11 pollution sources validated with chemical fingerprints. Crop residue burning and heating account for ~ 50 % of the PM, while traffic and industrial emissions dominate the gas-phase VOC burden and formation potential of secondary organic aerosols (> 60 %). Non-tailpipe emissions from compressed-natural-gas-fuelled commercial vehicles dominate the transport sector's PM burden.
Luke D. Schiferl, Cong Cao, Bronte Dalton, Andrew Hallward-Driemeier, Ricardo Toledo-Crow, and Róisín Commane
Atmos. Chem. Phys., 24, 10129–10142, https://doi.org/10.5194/acp-24-10129-2024, https://doi.org/10.5194/acp-24-10129-2024, 2024
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Carbon monoxide (CO) is an air pollutant and an important indicator of the incomplete combustion of fossil fuels in cities. Using 4 years of winter and spring observations in New York City, we found that both the magnitude and variability of CO from the metropolitan area are greater than expected. Transportation emissions cannot explain the missing and variable CO, which points to energy from buildings as a likely underappreciated source of urban air pollution and greenhouse gas emissions.
Chengzhi Xing, Cheng Liu, Chunxiang Ye, Jingkai Xue, Hongyu Wu, Xiangguang Ji, Jinping Ou, and Qihou Hu
Atmos. Chem. Phys., 24, 10093–10112, https://doi.org/10.5194/acp-24-10093-2024, https://doi.org/10.5194/acp-24-10093-2024, 2024
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We identified the contributions of ozone (O3) and nitrous acid (HONO) to the production rates of hydroxide (OH) in vertical space on the Tibetan Plateau (TP). A new insight was offered: the contributions of HONO and O3 to the production rates of OH on the TP are even greater than in lower-altitudes areas. This study enriches the understanding of vertical distribution of atmospheric components and explains the strong atmospheric oxidation capacity (AOC) on the TP.
Cited articles
Ambrose, J. L., Reidmiller, D. R., and Jaffe, D. A.: Causes of high O3 in the lower free troposphere over the Pacific Northwest as observed at the Mt. Bachelor Observatory, Atmos. Environ., 45, 5302–5315, https://doi.org/10.1016/j.atmosenv.2011.06.056, 2011.
Ambrose, J. L., Lyman, S. N., Huang, J., Gustin, M. S., and Jaffe, D. A.: Fast time resolution oxidized mercury measurements during the Reno Atmospheric Mercury Intercomparison Experiment (RAMIX), Environ. Sci. Technol., https://doi.org/10.1021/es303916v, 2013.
Amos, H. M., Jacob, D. J., Holmes, C. D., Fisher, J. A., Wang, Q., Yantosca, R. M., Corbitt, E. S., Galarneau, E., Rutter, A. P., Gustin, M. S., Steffen, A., Schauer, J. J., Graydon, J. A., St. Louis, V. L., Talbot, R. W., Edgerton, E. S., Zhang, Y., and Sunderland, E. M.: Gas-particle partitioning of atmospheric Hg(II) and its effect on global mercury deposition, Atmos. Chem. Phys., 12, 591–603, https://doi.org/10.5194/acp-12-591-2012, 2012.
Ariya, P. A., Khalizov, A., and Gidas, A.: Reactions of gaseous mercury with atomic and molecular halogens: Kinetics, product studies, and atmospheric implications, 106, J. Phys. Chem. A, 7310–7320, 2002.
Ariya, P. A., Dastoor, A. P., Amyot, M., Schroeder, W. H., Barrie, L., Anlauf, K., Raofie, F., Ryzhkov, A., Davignon, D., Lalonde, J., and Steffen, A.: The Arctic: a sink for mercury, Tellus, 56B, 397–403, 2004.
Calvert, J. G. and Lindberg, S. E.: Mechanisms of mercury removal by O3 and OH in the atmosphere, Atmos. Environ., 39, 3355–3367, 2005.
Cantrell, C. A.: Technical Note: Review of methods for linear least-squares fitting of data and application to atmospheric chemistry problems, Atmos. Chem. Phys., 8, 5477–5487, https://doi.org/10.5194/acp-8-5477-2008, 2008.
Chand, D., Jaffe, D., Prestbo, E., Swartzendruber, P. C., Hafner, W., Weiss-Penzias, P., Kato, S., Takami, A., Hatakeyama, S., and Kajii, Y.: Reactive and particulate mercury in the Asian marine boundary layer, Atmos. Environ., 42, 7988–7996, 2008.
Dibble, T. S., Zelie, M. J., and Mao, H.: Thermodynamics of reactions of ClHg and BrHg radicals with atmospherically abundant free radicals, Atmos. Chem. Phys., 12, 10271–10279, https://doi.org/10.5194/acp-12-10271-2012, 2012.
Donohoue, D., Bauer, D., Cossairt, B., and Hynes, A.: Temperature and pressure dependent rate coefficients for the reaction of Hg with Br and the reaction of Br with Br: A pulsed laser photolysispulsed laser induced fluorescence study, J. Phys. Chem. A., 110, 6623–6632, https://doi.org/10.1021/jp054688j, 2006.
Draxler, R. R. and Rolph, G. D.: HYSPLIT (HYbrid Single-Particle Lagrangian Integrated Trajectory) Model access via NOAA ARL READY Website (http://ready.arl.noaa.gov/HYSPLIT.php), NOAA Air Resources Laboratory, Silver Spring, MD, 2012.
Faïn, X., Obrist, D., Hallar, A. G., Mccubbin, I., and Rahn, T.: High levels of reactive gaseous mercury observed at a high elevation research laboratory in the Rocky Mountains, Atmos. Chem. Phys., 9, 8049–8060, https://doi.org/10.5194/acp-9-8049-2009, 2009.
Finley, B. D., Swartzendruber, P. C., and Jaffe, D. A.: Particulate mercury emissions in regional wildfire plumes observed at the Mount Bachelor Observatory, Atmos. Environ., 43, 6074–6083, 2009.
Fischer, E. V., Perry, K. D., and Jaffe, D. A.: Optical and chemical properties of aerosols transported to Mount Bachelor during spring 2010, J. Geophys. Res., 116, D18202, https://doi.org/10.1029/2011JD015932, 2011.
Fu, X., Feng, X., Sommar, J., and Wang, S. A.: Review of studies on atmospheric mercury in China, Sci. Total Environ., 421–422, 73–81, 2012.
Goodsite, M., Plane, J., and Skov, H.: A theoretical study of the oxidation of Hg0 to HgBr2 in the troposphere, Environ. Sci. Technol., 38, 1772–1776, https://doi.org/10.1021/es034680s, 2004.
Goodsite, M. E., Plane, J. M. C., and Skov, H.: Correction to A Theoretical Study of the Oxidation of Hg$^{\rm o}$ to HgBr2 in the Troposphere, Environ. Sci. Technol., 46, 5262–5262, https://doi.org/10.1021/es301201c, 2012.
Gustin, M. and Jaffe, D.: Reducing the uncertainty in measurement and understanding of mercury in the atmosphere, Environ. Sci. Technol., 44, 2222–2227, https://doi.org/10.1021/es902736k, 2010.
Gustin, M. S., Huang, J., Miller, M. B., Peterson, C., Jaffe, D. A., Ambrose, J., Finley, B. D., Lyman, S. N., Call, K., Talbot, R., Feddersen, D., Mao, H., and Lindberg, S. E.: Do we understand what the mercury speciation instruments are actually measuring? Results of RAMIX, Environ. Sci. Technol., https://doi.org/10.1021/es3039104, 2013.
Hand, J. L. and Malm, W. C.: Review of aerosol mass scattering efficiencies from ground-based measurements since 1990, J. Geophys. Res., 112, D16203, https://doi.org/10.1029/2007JD008484, 2007.
Haller, M. and Knochel, W.: X-ray fluorescence analysis using synchrotron radiation (SYXRF), J. Trace Microprobe Technol., 14, 461–488, 1996.
Hedgecock, I. M. and Pirrone, N.: Chasing Quicksilver: Modeling the Atmospheric Lifetime of Hg$^{0}_{(g)}$ in the Marine Boundary Layer at Various Latitudes, Environ. Sci. Technol., 38, 69–76, 2004.
Holmes, C. D., Jacob, D. J., Mason, R. P., and Jaffe, D. A.: Sources and deposition of reactive gaseous mercury in the marine atmosphere, Atmos. Environ., 43, 2278–2285, https://doi.org/10.1016/j.atmosenv.2009.01.051, 2009.
Holmes, C. D., Jacob, D. J., Corbitt, E. S., Mao, J., Yang, X., Talbot, R., and Slemr, F.: Global atmospheric model for mercury including oxidation by bromine atoms, Atmos. Chem. Phys., 10, 12037–12057, https://doi.org/10.5194/acp-10-12037-2010, 2010.
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