CaltechAUTHORS
Published February 2024 | Version Published
Journal Article Open

Assessing the importance of nitric acid and ammonia for particle growth in the polluted boundary layer

Creators

  • 1. ROR icon California Institute of Technology

Abstract

Aerosols formed and grown by gas-to-particle processes are a major contributor to smog and haze in megacities, despite the competition between growth and loss rates. Rapid growth rates from ammonium nitrate formation have the potential to sustain particle number in typical urban polluted conditions. This process requires supersaturation of gas-phase ammonia and nitric acid with respect to ammonium nitrate saturation ratios. Urban environments are inhomogeneous. In the troposphere, vertical mixing is fast, and aerosols may experience rapidly changing temperatures. In areas close to sources of pollution, gas-phase concentrations can also be highly variable. In this work we present results from nucleation experiments at −10 °C and 5 °C in the CLOUD chamber at CERN. We verify, using a kinetic model, how long supersaturation is likely to be sustained under urban conditions with temperature and concentration inhomogeneities, and the impact it may have on the particle size distribution. We show that rapid and strong temperature changes of 1 °C min−1 are needed to cause rapid growth of nanoparticles through ammonium nitrate formation. Furthermore, inhomogeneous emissions of ammonia in cities may also cause rapid growth of particles.

Copyright and License

This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence.

Acknowledgement

We thank the European Organization for Nuclear Research (CERN) for supporting CLOUD with technical and financial resources and for providing a particle beam from the CERN Proton Synchrotron. This research has received funding from the European Community (EC) Seventh Framework Programme and the European Union (EU) H2020 programme (Marie Skłodowska Curie ITN CLOUD-TRAIN grant number 316662 and CLOUD-MOTION grant number 764991); European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement no. 895875 (“NPF-PANDA”); the Swiss National Science Foundation (no. 200021 169090, 200020 172602, 20FI20 172622, and 200021 213071); the US National Science Foundation (NSF; grant numbers AGS1801574, AGS-NUC-1801897, and AGS132089); the German Ministry of Science and Education (project CLOUD-16, 01LK1601A), ACCC Flagship funded by the Academy of Finland grant number 337549; Academy professorship funded by the Academy of Finland (grant no. 302958); Academy of Finland projects no. 325656, 316114, 314798, 325647, 341349 and 349659; “Quantifying carbon sink, CarbonSink+ and their interaction with air quality” INAR project funded by Jane and Aatos Erkko Foundation; Jenny and Antti Wihuri Foundation project “Air pollution cocktail in Gigacity”, European Research Council (ERC) project ATM-GTP Contract No. 742206; the Arena for the gap analysis of the existing Arctic Science Co-Operations (AASCO) funded by Prince Albert Foundation Contract No. 2859; and the Portuguese Science Foundation, FCT, project CERN/FIS-COM/0028/2019. This research was performed before the invasion of Ukraine by Russia on 24 February 2022.

Contributions

Conceptualization: R. M., M. X., M. W., J. Dommen, J. K., N. M. D., H. L., U. B. and I. E. H., resources, prepared the CLOUD facility or measuring instruments: R. M., M. W., W. K., X.-C. H., D. S., J. P., G. M., D. S. W., A. B., C. P. L., A. A., D. M. B., R. B., L. C., L. D., J. Duplissy, H. F., M. H., K. L., H. E. M., B. M., T. P., M. P., B. R., W. S., J. S., Y. J. T., A. T., A. C. W., S. K. W., M. Z.-W., J. K., H. L., and I. E. H. Investigation: R. M., M. X., M. W., W. K., X.-C. H., D. S., J. P., G. M., D. S. W., A. B., C. P. L., R. B., D. M. B., B. B., L. C., L. D., J. Duplissy, H. F., M. H., M. L., H. E. M, B. M., W. S., J. S., Y. J. T., A. C. W., S. K. W., M. Z.-W., J. K., H. L., and I. E. H. Formal analysis: R. M., M. W., W. K., X. H., D. S., J. P., G. M., D. S. W., S. K. W., H. L., and I. E. H. Scientific discussion: R. M., M. X., M. W., W. K., X.-C. H., D. S., D. B., L. D., K. L., J. Dommen, R. C. F., J. K., N. M. D., H. L., U. B., and I. E. H. Writing: R. M., M. W., W. K., X.-C. H., D. S., J. Dommen, J. K., N. M. D., H. L., U. B., and I. E. H.

Conflict of Interest

There are no conflicts to declare.

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Additional details

Identifiers

PMCID
PMC10867809

Funding

European Organization for Nuclear Research
European Research Council
Marie Skłodowska Curie Fellowship 316662
European Research Council
764991
European Research Council
Marie Skłodowska Curie Fellowship 895875
Swiss National Science Foundation
200021 169090
Swiss National Science Foundation
200020 172602
Swiss National Science Foundation
20FI20 172622
Swiss National Science Foundation
200021 213071
National Science Foundation
AGS-1801574
National Science Foundation
AGS-1801897
National Science Foundation
AGS-132089
Ministry of Education and Science
01LK1601A
Research Council of Finland
337549
Research Council of Finland
302958
Research Council of Finland
325656
Research Council of Finland
316114
Research Council of Finland
314798
Research Council of Finland
325647
Research Council of Finland
341349
Research Council of Finland
349659
Jane and Aatos Erkko Foundation
Jenny ja Antti Wihurin Rahasto
Air pollution cocktail in Gigacity
European Research Council
742206
Prince Albert II of Monaco Foundation
2859
Fundação para a Ciência e Tecnologia
CERN/FIS-COM/0028/2019