Simulação da emissão e dispersão dos poluentes oriundos da queima de biomasa da cana de açúcar no estado de Alagoas utilizando o modelo atmosférico WRF/Chem

Abstract

In Brazil, the fire is generally used in sugar cane planting for the burning of straw and promoting clean the canebrake, making it easier for rural workers the cut and management of this vegetation. In the Alagoas state, one of the largest producers in the country in this culture, this procedure used during the process of harvest. In order to determine the impact of these fires in Alagoas, as well as presenting the transport of pollutants emitted during this process, the implementation of a system of chemical pre-processing data to serve as a basis for numerical model WRF/Chem performed. This system based on an inventory based on emissions of pollutants emitted during the burning of cane sugar from reference studies. This inventory feed with information of the pollutants (for this study were analyzed: CO and PM2,5), the burning focus detected by several satellites, available in CPTEC/INPE site. Analyzes were performed in the form of steps, as were implanted in the information system and for different periods. To make a direct evaluation of the results obtained for the transport and concentration of CO gas in the atmosphere of Alagoas, data for atmospheric sounding quality (AIRS) were used. This system of data collection, confirmed the direction of transport of pollutant cumulatively for study days by the model. To another step: to analyze the vertical configuration associated fires, the process called plume rise. This study analyzed its characteristics and influence during the burning of sugarcane in the ascension process of the plume resulting from positive buoyancy caused by the high temperatures of fires in contact with ambient air. It observed during the burning, close to the focus, a maximum concentration of 4000 ppbv CO and 60 μg/m³ for PM2,5. Of the according the intensity of the wind, it was possible to observe the transport of these pollutants for kilometers from the starting point of emission, this observation proved conditional, not only the action of the wind, but also by the amount of focus near one another, and the nature the pollutant, gas or aerosol. The CO, showed higher displacements due to their reactive nature little after being emitted and can be observed in everyday analysis, its influence on the atmosphere of the neighboring states Alagoas, at concentrations of 100-500 ppbv to a higher displacement 300 km , and closest, between 2000-2500 ppbv, at 100 km from the source locations. For PM2,5, due to its characteristic of solid pollutant, the process remains in the atmosphere is shorter. Transport of PM2,5 were analyzed in localities that had lots of focus of fire near, by moving the upper 100 km, at a concentration of 30-40 μg/m³. It was observed that the emission of fires focus actually have a near vertical rise burning sources, and in particular for PM2,5, observing the time of injection to about 1.7 km from the surface. Generally the BBEI tool for use in the numerical model WRF/Chem, demonstrated positive to represent the transport and concentration of emissions in studies of air quality due to biomass burning results.