Particulate matter fingerprints in biofuel impacted tunnels in South America's largest metropolitan area

Guilherme Martins Pereira; Thiago Nogueira; Leonardo Yoshiaki Kamigauti; Djacinto Monteiro Dos Santos; Emerson Queiroz Mota Nascimento; José Vinicius Martins; Ana Vicente; Paulo Artaxo; Célia Alves; Pérola de Castro Vasconcellos; Maria de Fatima Andrade

doi:10.1016/j.scitotenv.2022.159006

Particulate matter fingerprints in biofuel impacted tunnels in South America's largest metropolitan area

Sci Total Environ. 2023 Jan 15;856(Pt 2):159006. doi: 10.1016/j.scitotenv.2022.159006. Epub 2022 Sep 23.

Affiliations

¹ Departamento de Ciências Atmosféricas, Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Universidade de São Paulo, 05508-090 São Paulo, Brazil; Departamento de Química Fundamental, Instituto de Química, Universidade de São Paulo, 05508-000 São Paulo, Brazil. Electronic address: guilherme.martins.pereira@usp.br.
² Departamento de Ciências Atmosféricas, Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Universidade de São Paulo, 05508-090 São Paulo, Brazil.
³ Departamento de Física Aplicada, Instituto de Física, Universidade de São Paulo, 05508-090 São Paulo, Brazil.
⁴ Departamento de Química Fundamental, Instituto de Química, Universidade de São Paulo, 05508-000 São Paulo, Brazil.
⁵ Departamento de Mineralogia e Geotectônica, Instituto de Geociências, Universidade de São Paulo, 05508-080 São Paulo, Brazil.
⁶ Department of Environment and Planning, Centre for Environmental and Marine Studies (CESAM), University of Aveiro, 3810-193 Aveiro, Portugal.

PMID: 36162571
DOI: 10.1016/j.scitotenv.2022.159006

Abstract

This study characterized the chemical composition of particulate matter (PM) from light- (LDV) and heavy-duty (HDV) vehicles based on two traffic tunnel samplings carried out in the megacity of São Paulo (Brazil), which has >7 million vehicles and intense biofuel use. The samples were collected with high-volume samplers and analyzed using chemical characterization techniques (ion and gas chromatography, thermal-optical analysis, and inductively coupled plasma mass spectroscopy). Chemical source profiles (%) were calculated based on the measurements performed inside and outside the tunnels. Identifying a high abundance of Fe and Cu for traffic-related PM in the LDV-impacted tunnel was possible, linked with the emission of vehicles powered by ethanol and gasohol (gasoline and ethanol blend). We calculated diagnostic ratios (e.g., EC/Cu, Fe/Cu, pyrene/benzo[a]pyrene, pyrene/benzo[b]fluoranthene, and fluoranthene/benzo[b]fluoranthene) characteristic of fuel exhausts (diesel/biodiesel and ethanol/gasohol), allowing their use in the assessment of the temporal variation of the fuel type used in urban sites. Element diagnostic ratios (Cu/Sb and Fe/Cu) pointed to the predominance of LDVs exhaust-related copper and can differentiate LDVs exhaust from brake wear emissions. The carbonaceous fraction EC3 was suggested as an HDV emission tracer. A higher total polycyclic aromatic hydrocarbons (PAHs) fraction of traffic-related PM_2.5 was observed in the HDV-impacted tunnel, with a predominance of diesel-related pyrene and fluoranthene, as well as higher oxy-PAHs (e.g., 9,10-anthraquinone, associated with biodiesel blends) abundances. However, carcinogenic species presented higher abundances for the LDV-impacted tunnel (e.g., benzo[a]pyrene). These findings highlighted the impact of biofuels on the characteristic ratios of chemical species and pointed to possible markers for LDVs and HDVs exhausts.

Keywords: Biofuels; Heavy-duty vehicles; Light-duty vehicles; PAHs; Particulate matter.

MeSH terms

Air Pollutants* / analysis
Benzo(a)pyrene / analysis
Biofuels / analysis
Brazil
Environmental Monitoring / methods
Ethanol / analysis
Particulate Matter / analysis
Polycyclic Aromatic Hydrocarbons* / analysis
Vehicle Emissions / analysis

Substances

Particulate Matter
Biofuels
fluoranthene
Air Pollutants
Benzo(a)pyrene
Vehicle Emissions
Polycyclic Aromatic Hydrocarbons
Ethanol