Thesis defense:
Student: Iara da Silva
Program: Meteorology
Title: "Study of the Impact of Emissions from Fixed and Mobile Sources"
Advisor: Prof. Dr. Edmilson Dias de Freitas
Judging Committee
- Prof. Dr. Edmilson Dias de Freitas – Advisor
- Profa. Dra. Maria de Fatima Andrade – IAG/USP
- Prof. Dr. Luiz Cláudio Gomes Pimentel – UFRJ
- Profa. Dra. Taciana Toledo de Almeida Albuquerque – UFMG
- Profa. Dra. Vanessa Silveira Barreto Carvalho – UNIFEI
Abstract
With the growing process of urbanization and industrialization, the number of sources emitting atmospheric pollutants has increased significantly. The vehicle fleet in the state of São Paulo, for example, represents 25% of the country's circulating fleet. In addition to this significant vehicle source, the region has several fixed sources of emissions and presents continuous changes in land use. Emissions from these sources, together with other sources present in the state, interact dynamically in the atmosphere, influencing the formation of secondary pollutants such as tropospheric ozone (O3) and fine particulate matter (PM2.5). Although several studies have investigated the influence of emission sources on air quality, there are still scientific gaps regarding their impacts, especially in less urbanized areas, and regarding the role of atmospheric transport of pollutants in the spatial variability of concentrations. In this context, this research presents as main innovations the use of local inventories for the two main emission sources in the State of São Paulo and the comparison between two widely used modeling tools, the Weather Research and Forecasting model with Chemistry (WRF-Chem) and the Community Multiscale Air Quality (CMAQ). The use of local inventories allowed a more accurate and representative analysis of the emission sources in the region, while the comparison between the models allowed the evaluation of their performances and differences in the simulation of air quality. The performance of the atmospheric models, evaluated through statistical metrics, was within acceptable references. For the simulated conditions, WRF-Chem showed better performance in the simulation of O3, while CMAQ represented PM2.5 more accurately. The results indicate that vehicle emissions dominate the formation of O3 (responsible for up to 82% of the total in urban areas) and PM$_{2.5}$ (between 45\% and 72\%). On the other hand, industrial emissions have a more significant impact in peri-urban regions, contributing 7% to 34% of the O3 concentration and 13% to 27% of PM2.5. In areas with an industrial profile, industrial emissions can contribute up to 35% of the PM2.5 concentration and almost 50% of the O3 concentration. The modeling revealed that ozone chemistry varies spatially, with regions under VOC-limiting regime in the RMSP and NOx-limiting in the northwest of the state, considering the source sensitivity simulations. In addition, pollutant transport proved to be a critical factor. Emissions from the industrial hubs of Cubatão and Paulínia increased SO2 concentrations by up to 10 µg/m3 in neighboring municipalities. The sea breeze plays a relevant role, carrying particles from the coast to the interior of the state. These findings reinforce the importance of applying modeling to provide valuable results for the formulation of air pollution control strategies. Furthermore, they highlight the need to implement differentiated policies for specific emitting sectors, taking into account the impacts that may occur, even in areas far from the primary sources of pollution.
Keywords: Air pollution, modeling, WRF-Chem, CMAQ, emission sources