Composition and sources of atmospheric trace elements at three urban sites in Helsinki, Finland

Minna Aurela; K. Saarnio; Jarkko Niemi; Enna Turunen; K. Teinilä; Anu Kousa; H. E. Manninen; J. Hoivala; Mika Vestenius; T. Rönkkö; Anssi Järvinen; Hilkka Timonen; Sanna Saarikoski

doi:10.1016/j.atmosenv.2026.122233

Composition and sources of atmospheric trace elements at three urban sites in Helsinki, Finland

Minna Aurela^*
, K. Saarnio
, Jarkko Niemi
, Enna Turunen
, K. Teinilä
, Anu Kousa
, H. E. Manninen
, J. Hoivala
, Mika Vestenius
, T. Rönkkö
, Anssi Järvinen
, Hilkka Timonen
, Sanna Saarikoski

^*Corresponding author for this work

BA4802 Transport emission control

Finnish Meteorological Institute (FMI)
Helsinki Region Environmental Services Authority (HSY)
Tampere University

Research output: Contribution to journal › Article › Scientific › peer-review

Abstract

This study applies a positive matrix factorization (PMF) model to identify the sources of ambient fine (PM_2.5) and coarse (PM_2.5-10) particulate matter at two traffic sites and one urban background site in Helsinki, Finland. Over 700 24-h PM_2.5 and PM₁₀ filter samples were analysed using energy dispersive X-ray fluorescence, which quantified 12–19% of PM_2.5 and 22–29% of PM₁₀ mass. In the coarse particle fraction, Si had the highest concentrations, followed by Fe, Al, and Ca, while S, Fe, and either Na or Ca dominated the fine particle fraction. A 5-factor solution best represented the elemental sources, identifying Dust, Non-Exhaust Emissions (NEE), Aged Salt, Fresh Salt, and a mixed factor called here as Combustion/Secondary inorganic aerosol (SIA). Dust had the highest contribution at all sites, except for PM_2.5 at the urban background site, where Combustion/SIA was dominant. Dust was characterized by Al, Si, and Ti, while Combustion/SIA by S, V, Ni, Pb, and Se. Fresh salt was dominated by Cl, and Aged salt by Na and Mg. NEE was enriched in Cr, Fe, Cu, Zn, Ba, and Zr, suggesting primarily brake wear with possible tyre-wear contributions. Size distributions, measured with a 13-stage impactor at one of the sites, showed that elements related to Dust peaked at 5.6–10 μm and Combustion/SIA at 0.2–0.6 μm. Elements associated with NEE exhibited bimodal behaviour (<1 μm and 3–10 μm). In addition to ambient measurements, brake wear particles were studied in the laboratory to support the interpretation of source apportionment analysis.

Original language	English
Article number	122233
Journal	Atmospheric Environment
Volume	382
DOIs	https://doi.org/10.1016/j.atmosenv.2026.122233
Publication status	Published - 2026
MoE publication type	A1 Journal article-refereed

Funding

This work was done as a part of the NEX-EL project (7915/31/2022) funded by Business Finland, Helsinki Region Environmental Services Authority HSY, and participating companies, and the Research Council of Finland funding (grant no. 354844). Funding from the European Union Horizon 2020 research and innovation programme under Grant agreement No 101036245 (RIURBANS) is acknowledged. Filter samples originate from the projects ‘Quality program for air quality measurements: Demonstration of equivalence of PM10 and PM2.5 automated measurement systems in Finland 2022–2023’ and ‘Quality program for air quality measurements: Ongoing verification of suitability of automated measuring systems 2024’, both funded by the Ministry of the Environment and Finnish Meteorological Institute. This work belonged to the ACCC (Atmosphere and Climate Competence Center)-flagship (grant no. 337552, 337551) funded by the Research Council of Finland.

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

SDG 11 Sustainable Cities and Communities

Keywords

Air quality
Non-exhaust emissions
Particulate matter
PMF
Source apportionment
Trace elements
XRF

Access to Document

10.1016/j.atmosenv.2026.122233Licence: CC BY

Cite this

Aurela, M., Saarnio, K., Niemi, J., Turunen, E., Teinilä, K., Kousa, A., Manninen, H. E., Hoivala, J., Vestenius, M., Rönkkö, T., Järvinen, A., Timonen, H., & Saarikoski, S. (2026). Composition and sources of atmospheric trace elements at three urban sites in Helsinki, Finland. Atmospheric Environment, 382, Article 122233. https://doi.org/10.1016/j.atmosenv.2026.122233

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title = "Composition and sources of atmospheric trace elements at three urban sites in Helsinki, Finland",

abstract = "This study applies a positive matrix factorization (PMF) model to identify the sources of ambient fine (PM2.5) and coarse (PM2.5-10) particulate matter at two traffic sites and one urban background site in Helsinki, Finland. Over 700 24-h PM2.5 and PM10 filter samples were analysed using energy dispersive X-ray fluorescence, which quantified 12–19\% of PM2.5 and 22–29\% of PM10 mass. In the coarse particle fraction, Si had the highest concentrations, followed by Fe, Al, and Ca, while S, Fe, and either Na or Ca dominated the fine particle fraction. A 5-factor solution best represented the elemental sources, identifying Dust, Non-Exhaust Emissions (NEE), Aged Salt, Fresh Salt, and a mixed factor called here as Combustion/Secondary inorganic aerosol (SIA). Dust had the highest contribution at all sites, except for PM2.5 at the urban background site, where Combustion/SIA was dominant. Dust was characterized by Al, Si, and Ti, while Combustion/SIA by S, V, Ni, Pb, and Se. Fresh salt was dominated by Cl, and Aged salt by Na and Mg. NEE was enriched in Cr, Fe, Cu, Zn, Ba, and Zr, suggesting primarily brake wear with possible tyre-wear contributions. Size distributions, measured with a 13-stage impactor at one of the sites, showed that elements related to Dust peaked at 5.6–10 μm and Combustion/SIA at 0.2–0.6 μm. Elements associated with NEE exhibited bimodal behaviour (<1 μm and 3–10 μm). In addition to ambient measurements, brake wear particles were studied in the laboratory to support the interpretation of source apportionment analysis.",

keywords = "Air quality, Non-exhaust emissions, Particulate matter, PMF, Source apportionment, Trace elements, XRF",

author = "Minna Aurela and K. Saarnio and Jarkko Niemi and Enna Turunen and K. Teinil{\"a} and Anu Kousa and Manninen, \{H. E.\} and J. Hoivala and Mika Vestenius and T. R{\"o}nkk{\"o} and Anssi J{\"a}rvinen and Hilkka Timonen and Sanna Saarikoski",

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doi = "10.1016/j.atmosenv.2026.122233",

language = "English",

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journal = "Atmospheric Environment",

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T1 - Composition and sources of atmospheric trace elements at three urban sites in Helsinki, Finland

AU - Aurela, Minna

AU - Saarnio, K.

AU - Niemi, Jarkko

AU - Turunen, Enna

AU - Teinilä, K.

AU - Kousa, Anu

AU - Manninen, H. E.

AU - Hoivala, J.

AU - Vestenius, Mika

AU - Rönkkö, T.

AU - Järvinen, Anssi

AU - Timonen, Hilkka

AU - Saarikoski, Sanna

PY - 2026

Y1 - 2026

N2 - This study applies a positive matrix factorization (PMF) model to identify the sources of ambient fine (PM2.5) and coarse (PM2.5-10) particulate matter at two traffic sites and one urban background site in Helsinki, Finland. Over 700 24-h PM2.5 and PM10 filter samples were analysed using energy dispersive X-ray fluorescence, which quantified 12–19% of PM2.5 and 22–29% of PM10 mass. In the coarse particle fraction, Si had the highest concentrations, followed by Fe, Al, and Ca, while S, Fe, and either Na or Ca dominated the fine particle fraction. A 5-factor solution best represented the elemental sources, identifying Dust, Non-Exhaust Emissions (NEE), Aged Salt, Fresh Salt, and a mixed factor called here as Combustion/Secondary inorganic aerosol (SIA). Dust had the highest contribution at all sites, except for PM2.5 at the urban background site, where Combustion/SIA was dominant. Dust was characterized by Al, Si, and Ti, while Combustion/SIA by S, V, Ni, Pb, and Se. Fresh salt was dominated by Cl, and Aged salt by Na and Mg. NEE was enriched in Cr, Fe, Cu, Zn, Ba, and Zr, suggesting primarily brake wear with possible tyre-wear contributions. Size distributions, measured with a 13-stage impactor at one of the sites, showed that elements related to Dust peaked at 5.6–10 μm and Combustion/SIA at 0.2–0.6 μm. Elements associated with NEE exhibited bimodal behaviour (<1 μm and 3–10 μm). In addition to ambient measurements, brake wear particles were studied in the laboratory to support the interpretation of source apportionment analysis.

AB - This study applies a positive matrix factorization (PMF) model to identify the sources of ambient fine (PM2.5) and coarse (PM2.5-10) particulate matter at two traffic sites and one urban background site in Helsinki, Finland. Over 700 24-h PM2.5 and PM10 filter samples were analysed using energy dispersive X-ray fluorescence, which quantified 12–19% of PM2.5 and 22–29% of PM10 mass. In the coarse particle fraction, Si had the highest concentrations, followed by Fe, Al, and Ca, while S, Fe, and either Na or Ca dominated the fine particle fraction. A 5-factor solution best represented the elemental sources, identifying Dust, Non-Exhaust Emissions (NEE), Aged Salt, Fresh Salt, and a mixed factor called here as Combustion/Secondary inorganic aerosol (SIA). Dust had the highest contribution at all sites, except for PM2.5 at the urban background site, where Combustion/SIA was dominant. Dust was characterized by Al, Si, and Ti, while Combustion/SIA by S, V, Ni, Pb, and Se. Fresh salt was dominated by Cl, and Aged salt by Na and Mg. NEE was enriched in Cr, Fe, Cu, Zn, Ba, and Zr, suggesting primarily brake wear with possible tyre-wear contributions. Size distributions, measured with a 13-stage impactor at one of the sites, showed that elements related to Dust peaked at 5.6–10 μm and Combustion/SIA at 0.2–0.6 μm. Elements associated with NEE exhibited bimodal behaviour (<1 μm and 3–10 μm). In addition to ambient measurements, brake wear particles were studied in the laboratory to support the interpretation of source apportionment analysis.

KW - Air quality

KW - Non-exhaust emissions

KW - Particulate matter

KW - PMF

KW - Source apportionment

KW - Trace elements

KW - XRF

UR - https://www.scopus.com/pages/publications/105045096643

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DO - 10.1016/j.atmosenv.2026.122233

M3 - Article

AN - SCOPUS:105045096643

SN - 1352-2310

VL - 382

JO - Atmospheric Environment

JF - Atmospheric Environment

M1 - 122233

ER -

Composition and sources of atmospheric trace elements at three urban sites in Helsinki, Finland

Abstract

Funding

UN SDGs

Keywords

Access to Document

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NEX-EL: Non-exhaust emissions in electrifying mining and urban environment

Cite this

Composition and sources of atmospheric trace elements at three urban sites in Helsinki, Finland

Abstract

Funding

UN SDGs

Keywords

Access to Document

Other files and links

Fingerprint

Projects

NEX-EL: Non-exhaust emissions in electrifying mining and urban environment

Cite this