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Significant advances in atmospheric aerosol research

  • Environment and natural resources

The Aerosol Physics Research Group in the Department of Applied Physics at the University of Eastern Finland has been very busy – even more than usual– in finding solutions to key issues around atmospheric aerosols. Prime examples of this work are the group’s recent articles in Nature and Science Advances, which were published as a result of collaboration with the CLOUD experiment at CERN, Switzerland. The articles focus on air pollution, and especially on the effect of nitric compounds on the formation and growth of aerosol particles.

Associate Professor Taina Yli-Juuti and Early Stage Researcher Arto Heitto, both members of the Aerosol Physics Research Group, contributed to the Nature article on the role of nitric acid and ammonia by developing a process model that can describe aerosol particle growth in polluted environments.

“The findings show that simultaneous condensation of nitric acid and ammonia can increase the size of nanometre-scale atmospheric particles 10–100 times faster than any previously identified mechanism; however, this will just be a quick growth spurt. This new mechanism may explain particle formation events in polluted large cities especially during the winter months – a phenomenon that has puzzled researchers during recent years,” Yli-Juuti explains.

Aerosol particle formation and growth under different atmospheric conditions is one of the group’s key research themes. Research addressing the formation, properties and climate effects of aerosol particles formed in boreal forests also plays an important role in the group’s research. In this theme, the group has recently published several high-profile studies, as exemplified by two articles published in Nature Communications in late 2019, and an article published in Nature Protocols earlier this year. All of the articles address key issues relating to the growth of organic aerosol particles formed in forests.

In addition, new and interesting findings in this topic have just been published, or have been accepted for publication, in the field’s leading journals. These new findings show that the volatility of organic compounds plays a key role both in particle growth and dispersion; however, also particle phase reactions are important.

“We have determinedly and persistently developed both experimental and modelling methods which provide us with new tools for studying the key processes relating to aerosol particle formation and their properties. Now that our toolbox is starting to be impressive even by international comparison, we will be seeing more and more interesting results, Professor Annele Virtanen says.

The findings will have even more impact if they can be incorporated in global climate models in the form of, e.g. new parametrizations, which will make predictions of aerosols’ climate effects increasingly accurate. Indeed, in the field of climate models, the group collaborates closely with the Finnish Meteorological Institute’s unit in Kuopio.

“In recent years, collaboration with the University of Eastern Finland’s scholars of climate law has also increased the impact of our research,” says Professor Kari Lehtinen.

“A recent example of this is a study published in Atmospheric Chemistry and Physics, exploring how the mitigation of black carbon in the Arctic Council’s member and observer states would influence both the Arctic and the global climate.”

For further information, please contact:

Associate Professor Taina Yli-Juuti, taina.yli-juuti (a) uef.fi

Associate Professor Siegfried Schobesberger, siegfried.schobesberger (a) uef.fi

Professor Annele Virtanen, annele.virtanen (a) uef.fi

Professor Kari Lehtinen, kari.lehtinen (a) uef.fi

 

Research articles:

Wang, M., Kong, W., Marten, R., He, X.-C., Chen, D., Pfeifer, J., Heitto, A., Kontkanen, J., Dada, L., Kürten, A., Yli-Juuti, T. et al. Rapid growth of new atmospheric particles by nitric acid and ammonia condensation. Nature, 581(7807), 184–189, doi:10.1038/s41586-020-2270-4.

C. Yan, et al. Size-dependent influence of NOx on the growth rates of organic aerosol particles. Sci. Adv. 6, eaay4945 (2020).  DOI: 10.1126/sciadv.aay4945 https://advances.sciencemag.org/content/6/22/eaay4945

Dada, L., K. Lehtipalo, J. Kontkanen, T. Nieminen, R. Baalbaki, L. Ahonen, J. Duplissy, C. Yan, B. Chu, T. Petäjä, K. Lehtinen, V.-M. Kerminen, M. Kulmala & J. Kangasluoma. (2020)
Formation and growth of sub-3-nm aerosol particles in experimental chambers.
Nature Protocols. doi:10.1038/s41596-019-0274-z.

Mohr, C., Thornton, J. A., Heitto, A., Lopez-Hilfiker, F. D., Lutz, A., Riipinen, I., Hong, J., Donahue, N. M., Hallquist, M., Petäjä, T., Kulmala, M. and Yli-Juuti, T. (2019)
Molecular identification of organic vapors driving atmospheric nanoparticle growth.
Nature Communications, 10(1), 4442, doi:10.1038/s41467-019-12473-2.

Roldin, P., Ehn, M., Kurtén, T., Olenius, T., Rissanen, M. P., Sarnela, N., Elm, J., Rantala, P., Hao, L., Hyttinen, N., Heikkinen, L., Worsnop, D. R., Pichelstorfer, L., Xavier, C., Clusius, P., Öström, E., Petäjä, T., Kulmala, M., Vehkamäki, H., Virtanen, A., Riipinen, I. and Boy, M. (2019)
The role of highly oxygenated organic molecules in the Boreal aerosol-cloud-climate system.
Nature Communications, 10(1), 4370, doi:10.1038/s41467-019-12338-8.

Ylisirniö, A., Buchholz, A., Mohr, C., Li, Z., Barreira, L., Lambe, A., Faiola, C., Kari, E., Yli-Juuti, T., Nizkorodov, S. A., Worsnop, D. R., Virtanen, A., and Schobesberger, S. (2020)
Composition and volatility of secondary organic aerosol (SOA) formed from oxidation of real tree emissions compared to simplified volatile organic compound (VOC) systems.
Atmos. Chem. Phys., 20, 5629–5644, doi:10.5194/acp-20-5629-2020.

Kühn, T., Kupiainen, K., Miinalainen, T., Kokkola, H., Paunu, V.-V., Laakso, A., Tonttila, J., Van Dingenen, R., Kulovesi, K., Karvosenoja, N., and Lehtinen, K. E. J. (2020)
Effects of black carbon mitigation on Arctic climate.
Atmos. Chem. Phys., 20, 5527–5546, doi:10.5194/acp-20-5527-2020.

Buchholz, A., Ylisirniö, A., Huang, W., Mohr, C., Canagaratna, M., Worsnop, D. R., Schobesberger, S., and Virtanen, A. (2019)
Deconvolution of FIGAERO-CIMS thermal desorption profiles using positive matrix factorisation to identify chemical and physical processes during particle evaporation.
Accepted to Atmos. Chem. Phys., doi:10.5194/acp-2019-926.