Isoprene in urban Atlantic forests: Variability, origin, and implications on the air quality of a subtropical megacity

Author(s)

dos Santos, Tailine C. ; Dominutti, Pamela ; Pedrosa, Giselle S. ; Coelho, Monique S. ; Nogueira, Thiago ; Borbon, Agnes ; Souza, Silvia R. ; Fornaro, Adalgiza

• Document type: Journal article
• Source: Science of The Total Environment; v. 824, p. 14-pg., 2022-06-10.

Abstract

Biosphere-atmosphere interactions play a key role in urban chemistry because of biogenic volatile organic compound (BVOC) emissions. Of the BVOC, isoprene is the most emitted compound; however, it also has anthropogenic origins in urban areas. In this study, we aimed to investigate the spatio-temporal variability and atmospheric impacts of biogenic and anthropogenic isoprene in the subtropical megacity of Sao Paulo (MASP), Brazil. Several measurement campaigns were conducted in three different urban Atlantic forests (Matao, PEFI, and RMG), and an urban background site (IAG); this equated to a total of 268 samples for the 2018-2019 period. For all sampling points, daytime average concentrations of isoprene were two to three times higher during the rainy season (IAG: 1.75 +/- 0.93 ppb; Matao: 0.87 +/- 0.35 ppb; PEFI: 0.50 +/- 0.30 ppb; RMG: 0.37 +/- 0.18 ppb), than those observed during the dry season (IAG: 0.46 +/- 0.24 ppb; Matao: 0.31 +/- 0.17 ppb; PEFI: 0.17 +/- 0.11 ppb; RMG: 0.11 +/- 0.07 ppb). Average isoprene concentrations were similar to those observed in other places worldwide, with the exception of theAmazon forest. Our results indicate differences in isoprene concentrations between sites, suggesting that environmental conditions such as the urban heat island and vegetation types, may play a role in spatial variability. Estimates of the isoprene fraction indicated that the biogenic fraction (85%) surpassed the anthropogenic fraction during the rainy season. By contrast, the anthropogenic fraction (52%) exceeded the biogenic fraction during dry periods. These fractions have an impact on potentially forming secondary pollutants gaseous (ozone formation potential: 7.19-33.32 mu g m(-3)), and aerosols (secondary organic aerosols formation potential: 0.41-1.88 mu g m(-3)). These results highlight the role of biogenic isoprene and its potential impact on urban air quality in subtropicalmegacities; this requires further investigation under future climate change scenarios. (AU)

• FAPESP's process: 16/25109-3 - plant volatiles in remnants of Atlantic Forest under the antropogenic influence
• Grantee: Silvia Ribeiro de Souza
• Support Opportunities: Regular Research Grants
• FAPESP's process: 17/50278-6 - BIOMASP: biogenic VOCs in the metropolitan area of São Paulo
• Grantee: Adalgiza Fornaro
• Support Opportunities: Regular Research Grants
• FAPESP's process: 15/50128-9 - Astrid - accessibility, social justice and transport emission impacts of transit-oriented development strategies
• Grantee: Adalgiza Fornaro
• Support Opportunities: Research Projects - Thematic Grants