An experiment to evaluate the effect of seasonal biomass burnings in central Brazil and the Amazon region on the increase in concentrations of carbon monoxide from tropospheric ozone in Southeast Brazil

Abstract

A study is proposed to evaluate the impact of emissions from biomass burning in central Brazil and Amazonia in the composition of the atmosphere of the Southeast region of Brazil, in particular the Vale do Paraíba, São Paulo. This proposal envisages implementing an atmospheric chemical experiment in this region, with measurements at surface level of the concentrations of carbon monoxide (CO) and ozone (O3), in addition to other long life gases, and the launching of balloons with probes for measurements of ozone and aerosol particles. The experimental measurements will be planned and have their results analyzed in real time, with the aid of results from a transport model of pollutants emitted by biomass burning and by sources associated with urban industrial areas. Preliminary observations carried out in the region of the Vale do Paraíba shows a complex structure of data, with high variability in the values observed of concentrations of trace gases. The concentration of CO in Vale do Paraíba is typically of the order of 300 ppbv, but in some cases much higher values, above 600 ppbv, rising to reach 1,600 ppbv, were observed. A preliminary analysis of retrograde trajectories of the air masses indicates the possibility of completely different contributions. There could be supremacy of anthropogenic sources from the metropolitan areas of Rio de Janeiro and São Paulo, or from the emissions of seasonal biomass burning in central Brazil and Amazonia. It also has to be taken into consideration that the region of Vale do Paraíba is importante and industrially developed, constituting, therefore, a significant local source of pollutants. It is of great interest to investigate better how the incidental air masses are constituted and the relative role of each one of the contributions. The surface measurements will be carried out in a container, which is, in fact, a transportable laboratory for group use, with which other projects have already been carried out. Inside it we will centralize the continuous measurements of O3 and CO2. The measurements of CO (and CH4, which will be sued to discriminate the origin of the sample) will be obtained through grab samples, which are taken to the laboratory in special sampling flasks, where they are analyzed by gas chromatography. It is proposed to complemente the observations at surface level with measurements of O3 and of particulate matter at different vertical levels, through the use of probes launched in balloons. Our proposal is to launch balloons with ozone probes, but also another type of launch, using larger balloons, which also carry a special probe to measure the vertical distribution of aerosol particles. The Inpe ozone group already carried out these measurements, systematically, in Natal, Rio Grande do Norte, and sporadically in other locations in Brazil and Antarctica. Similarly, the Cptec group has carried out air quality monitoring on a regional scale through numerical modeling. His study has demonstrated the role of transport processes on different scales, from turbulence to convection and advection, in the definition of the spatial and vertical distribution of atmospheric pollutants originating from biomass burnings and other anthropogenic sources. (AU)