Dissertation defense
Student: Avila Benaya dos Santos Sousa
Program: Meteorology
Title: “Temporal Variation in the Composition of Aromatic Compounds in the Metropolitan
Region of São Paulo. ”
Advisor: Profa. Dra. Adalgiza Fornaro - IAG/USP
Judging comitee:
- Profa. Dra. Adalgiza Fornaro – Presidente e Orientadora - IAG/USP
- Prof. Dr. Cleyton Martins da Silva – UVA (por videoconferência)
- Prof. Dr. Bruno Ruiz Brandão da Costa - IB/USP
Abstract: Resumo da tese em inglês: This study investigates the composition and temporal variability of volatile aromatic compounds (BTEX: benzene, toluene, ethylbenzene, and xylenes) in the Metropolitan Region of São Paulo (MRSP), focusing on emission source identification, seasonal patterns, and global comparisons. Hourly data of 16 aromatic compounds were analyzed from measurements conducted at IAG-USP between 2013 and 2015 using thermal desorption coupled with gas chromatography and flame ionization detection (TD GC-FID), in addition to long- term series from CETESB’s automatic and manual monitoring networks (2013–2024). The results showed that toluene was the most abundant compound, with average concentrations exceeding 12 µg/m³ in urban and industrial areas, followed by benzene, ranging from 0.7 to 2.9 µg/m³, with the highest levels observed at Capuava (Santo André) and Cubatão, sites affected by industrial emissions. The benzene/ toluene ratio (B/T), used as an indicator of source type and atmospheric aging, ranged from 0.2 to 0.9, reflecting a predominance of vehicular sources and the influence of local meteorological and industrial conditions. Seasonal analysis revealed higher concentrations during winter, attributed to greater atmospheric stability, and lower levels in summer due to rainfall and enhanced photochemical activity. A decreasing trend in BTEX concentrations was observed over the years, consistent with improvements in fuel composition, vehicle technologies, and emission control policies. Additionally, a comprehensive literature review of international studies since the 1980s was conducted, enabling the construction of a global overview of BTEX concentrations. Results indicate that the MRSP shares similarities with other megacities worldwide, although critical areas still present elevated levels. These findings enhance the understanding of BTEX dynamics in urban environments and support the development of air quality management strategies and public policies aimed at pollution mitigation.
Keywords: BTEX, aromatic compounds, temporal variability, emission sources, air quality, air pollution, MASP, gas chromatography, B/T ratio