Airborne measurements of aerosols from burning biomass in Brazil related to the TRACE A experiment

Abstract

Results are reported from an airborne campaign to investigate the impacts of burning biomass upon the loading of lower‐tropospheric aerosols and its composition over the Brazilian tropics. The flights, conducted as part of the NASA/Transport and Atmospheric Chemistry Near the Equator‐Atlantic (TRACE A) mission, started on September 1, 1992, when the dry (fire) season still prevailed in the central part of Brazil, and ended on September 29. Of the total number of burnings detected in Brazil by the advanced very high resolution radiometer (AVHRR)/NOAA satellite sensor, 74% were concentrated in the states of Amazonas, Maranhão, Mato Grosso, Pará, Roraima, and Tocantins during this period. Aerosol particles were sampled from a twin‐engine aircraft in transit and vertical profile flights were made up to 4,000 m altitude. Black carbon measurements made in real time and in areas of burning biomass peaked at ∼2,500 m above the ground, increasing to ∼12,000 ng/m3. In other areas these values were lower by 1 order of magnitude. A condensation nuclei counter measuring small particles (>0.014 μm) produced values ranging from 2,000 to 16,000/cm3 for areas with low and high burning biomass, respectively. Deposition filters in a two‐stage cascade impactor, and Nuclepore filters collected aerosols for analysis of 13 elements through particle‐induced X ray emissions (PIXE). Primary elements associated with soil dust (Al, Si, Mn, Fe, Ni) prevailed in the aerosol coarse mode (>1 μm) while the fine mode aerosols were enriched in S, K, Br, and Rb, which are tracers normally associated with burning of biomass. The good correlation between fire spot counts, obtained via AVHRR aboard NOAA satellites, and black carbon, counts of small particles and total aerosol mass, suggests the determining of local concentrations of fire‐derived aerosol fire emissions by satellite to be a new and useful approach.

Characterization and source identification of a fine particle episode in Finland

“…The median S/K ratios of S-rich particles were 2.1 at the beginning of the episode, 5.2 at the peak stage of the episode and 8.9 during the reference days. The values occurring at the beginning of the episode were very high compared with the S/K ratios measured near the biomass burning sources (S/K-ratio $0.1: Gaudichet et al, 1995;Turn et al, 1997;Christensen et al, 1998;Hedberg et al, 2002), but quite similar to the typical values measured from hazes farther distant from the burning areas (K/S-ratio $0.4-2.3: Andreae et al, 1988;Artaxo et al, 1994;Pereira et al, 1996). However, during the peak stage of the episode, the S/K ratio was clearly higher compared to that occurring during the beginning of the episode and other previously mentioned studies.…”

A review of biomass burning emissions part II: intensive physical properties of biomass burning particles

“…A portion of this variability is no doubt due to the presence of other species in the atmosphere. However, receptor modeling in regions impacted by smoke such as multivariate analysis (e.g., Maenhaut et al, 1996), and principal component analysis (e.g., Artaxo et al, 1994Artaxo et al, , 1998Echalar et al, 1998;Pereira et al, 1996;Reid et al, 1998b) has little trouble extracting the smoke apportionment. Understandably, these methods easily extract the key tracer species for smoke, principally black carbon, potassium, and secondary sulfate.…”

Characterization of aerosol particle episodes in Finland caused by wildfires in Eastern Europe

“…Intensive fires also mobilize particles from the surfaces of plants and the ground (Allen and Miguel, 1995;Gaudichet et al, 1995;Pereira et al, 1996). The injection heights of particles from forest fires are in moderate surface fires usually ∼2.3 km or less and in intensive crown fires ∼5-12 km (Lavoue et al, 2000).…”