Estudo dos compostos orgânicos voláteis precursores de ozônio para a Região Metropolitana do Rio de Janeiro

Abstract

Tropospheric ozone plays a central role in an urban atmosphere, it is formed mainly from the interaction between nitrogen oxides (NOx) and Volatile Organic Compounds (VOCs). Since it is a secondary pollutant, control and action on ozone concentrations depend on the control of their precursors. Therefore, the main goal of this study is to determine the VOCs present in the Metropolitan Region of Rio de Janeiro (RMRJ), in order to obtain a minimum set that could be representative to simulate ozone formation. The study is focused on the 57 most significant compounds for ozone formation, according to U.S.EPA, and applies the TO-15 Method, reactivity analysis and simulation of air quality. Typical urban atmosphere samples were used to validate Method TO-15 Method, wich was further applied to analyse samples collected in differents places of the RMRJ. Kinetic and mechanistic reactivity studies, as well as a descriptive and multivariate statistical analysis were performed. Thus, a minimal set, consisting of 14 VOCs was determined. Using this set, ozone concentrations were calculated and the value differed in less than 10% from the value obtained using the initial total VOCs group. It can be concluded that it is possible to determine a minimum set of VOCs, which is suitable for the simulation of ozone formation, in the present scenario, avoiding the laborious analysis of all the compounds. Also the importance of monitoring aromatic VOCs (due to their respective toxicities) and isoprene (main biogenic VOC), which were present in the minimum VOCs set, proposed by this work, may be highlighted