Atmospheric concentrations of monoterpenes and sesquiterpenes at urban Forests of São Paulo, SE-Brazil: winter and summertime observations in 2017-2018

Abstract

The study compares the atmospheric composition of biogenic organic compounds (BVOCs), specifically mono and sesquiterpenes, between two sites in the Metropolitan region of São Paulo- Brazil. One site is situated in the peripheral regions characterized by a high density of trees (PEFI), while the other site is located on the university campus of São Paulo (USP) and is highly affected by vehicular emission. The highest levels were observed in both sites during winter/2017. Different emission patterns were noted between the sites, α-pinene, associated with coniferous trees, was notably high at USP during winter, likely due to the presence of exotic tree species like eucalyptus and pines. However, d-limonene, another compound emitted by conifers, was lower in summer, confirming findings from other regions. Meteorological factors such as temperature, humidity, wind speed, and ozone levels influenced BVOC concentrations differently at each site and across seasons. For instance, higher temperatures negatively impacted BVOC levels at PEFI in winter but did not affect them in USP during summer. Biogenic emissions appear to be the main source of mono and sesquiterpenes in the PEFI, whereas, at the USP site, both vehicle emissions and biogenic emissions contribute to the levels of these compounds. The study suggests that factors influencing BVOC levels in the atmosphere are not solely related to expected biogenic emissions but also to meteorological parameters, their reactivity, and additional sources that have not yet been fully investigated.