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

Author(s):Show less -

Pereira, Guilherme Martins ; Nogueira, Thiago ; Kamigauti, Leonardo Yoshiaki ; dos Santos, Djacinto Monteiro ; Nascimento, Emerson Queiroz Mota ; Martins, Jose Vinicius ; Vicente, Ana ; Artaxo, Paulo ; Alves, Celia ; Vasconcellos, Perola de Castro ; Andrade, Maria de Fatima

• Document type: Journal article
• Source: Science of The Total Environment; v. 856, p. 13-pg., 2023-01-15.

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 Sao 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 PM2.5 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 ra-tios of chemical species and pointed to possible markers for LDVs and HDVs exhausts. (AU)

• FAPESP's process: 18/07848-9 - Chemical and toxicological source profiling of particulate matter in urban air - SOPRO
• Grantee: Maria de Fátima Andrade
• Support Opportunities: Regular Research Grants
• FAPESP's process: 16/18438-0 - São Paulo Metropolitan Area, jointly tracking climate change and air quality - METROCLIMA-MASP
• Grantee: Maria de Fátima Andrade
• Support Opportunities: Research Program on Global Climate Change - Thematic Grants