Ethanol, acetaldehyde, and methanol in the gas phase and rainwater in different biomes and urban regions of Brazil

Author(s)

Florencio, Jacques ; Scaramboni, Caroline ; Giubbina, Fernanda Furlan ; De Martinis, Bruno Spinosa ; Fornaro, Adalgiza ; Felix, Erika Pereira ; De Oliveira, Tereza Cristina Souza ; Campos, Maria Lucia Arruda Moura

• Document type: Journal article
• Source: Science of The Total Environment; v. 929, p. 11-pg., 2024-04-25.

Abstract

In the context of the increasing global use of ethanol biofuel, this work investigates the concentrations of ethanol, methanol, and acetaldehyde, in both the gaseous phase and rainwater, across six diverse urban regions and biomes in Brazil, a country where ethanol accounts for nearly half the light-duty vehicular fuel consumption. Atmospheric ethanol median concentrations in S & atilde;o Paulo (SP) (12.3 +/- 12.1 ppbv) and Ribeir & atilde;o Preto (RP) (12.1 +/- 10.9 ppbv) were remarkably close, despite the SP vehicular fleet being similar to 13 times larger. Likewise, the rainwater VWM ethanol concentration in SP (4.64 +/- 0.38 mu mol L-1) was only 26 % higher than in RP (3.42 +/- 0.13 mu mol L-1). This work demonstrated the importance of evaporative emissions, together with biomass burning, as sources of the compounds studied. The importance of biogenic emissions of methanol during forest flooding was identified in campaigns in the Amazon and Atlantic forests. Marine air masses arriving at a coastal site led to the lowest concentrations of ethanol measured in this work. Besides vehicular and biomass burning emissions, secondary formation of acetaldehyde by photochemical reactions may be relevant in urban and non-urban regions. The combined deposition flux of ethanol and methanol was 6.2 kg ha(-1) year(-1), avoiding oxidation to the corresponding and more toxic aldehydes. Considering the species determined here, the ozone formation potential (OFP) in RP was around two-fold higher than in SP, further evidencing the importance of emissions from regional distilleries and biomass burning, in addition to vehicles. At the forest and coastal sites, the OFP was approximately 5 times lower than at the urban sites. Our work evidenced that transition from gasoline to ethanol or ethanol blends brings the associated risk of increasing the concentrations of highly toxic aldehydes and ozone, potentially impacting the atmosphere and threatening air quality and human health in urban areas. (AU)

• FAPESP's process: 20/07141-2 - Biogenic emissions, chemistry and impacts in the Metropolitan Area of São Paulo: BIOMASP+
• Grantee: Adalgiza Fornaro
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 18/16554-9 - Assessing the impact of atmospheric emissions related to the production and use of ethanol in the perspective of the current public policies of biofuels
• Grantee: Maria Lúcia Arruda de Moura Campos
• Support Opportunities: Regular Research Grants
• FAPESP's process: 18/17931-0 - Atmospheric particulate matter from a region impacted by biomass burning: sources and toxicity
• Grantee: Caroline Scaramboni
• Support Opportunities: Scholarships in Brazil - Doctorate