• Energy Research

This study was conducted at three sites of different characteristics in São Paulo State: São Paulo (SPA), Piracicaba (PRB) and Mata Atlântica Forest (MAT). PM(10), n-alkanes, pristane and phytane, PAHs, water-soluble ions and biomass burning tracers like levoglucosan and retene, were determined in quartz fiber filters. Samplings occurred on May 8th to August 8th, 2007 at the MAT site; on August 15th to 29th in 2007 and November 10th to 29th in 2008 at the PRB site and, March 13th to April 4th in 2007 and August 7th to 29th in 2008 at the SPA site. Aliphatic compounds emitted biogenically were less abundant at the urban sites than at the forest site, and its distribution showed the influence of tropical vascular plants. Air mass transport from biomass burning regions is likely to impact the sites with specific molecular markers. The concentrations of all species were variable and dependent of seasonal changes. In the most dry and polluted seasons, n-alkane and cation total concentrations were similar between the megacity and the biomass burning site. PAHs and inorganic ion abundances were higher at São Paulo than Piracicaba, yet, the site influenced by biomass burning seems to be the most impacted by the organic anion abundance in the atmosphere. Pristane and phytane confirm the contamination by petroleum residues at urban sites; at the MAT site, biological activity and long range transport of pollutants might influence the levels of pristane.

In the present study Tradescantia pallida micronucleus (Trad-MCN) bioassay was used to assess the genotoxicity of particulate matter with a mass median aerodynamic diameter less than 10 μm (PM₁₀) in Tangara da Serra (MT), a Brazilian Amazon region that suffers the impact of biomass burning. The levels of PM (coarse and fine size fractions) and black carbon (BC) collected were also measured. Furthermore, the alkanes and polycyclic aromatic hydrocarbons (PAHs) were identified and quantified in the samples taken during the burning period by gas chromatography with flame ionization detection (GC-FID). The PM and BC results for both fractions indicate a strong correlation (p < 0.001). The analysis of alkanes indicates an anthropic influence. Retene was the most abundant PAH found, an indicator of biomass burning, and 12 other PAHs considered to be potentially mutagenic and/or carcinogenic were identified in this sample. The Trad-MCN bioassay showed a significant increase in micronucleus frequency during the period of most intense burning, possibly related to the mutagenic PAHs that were found in such extracts. This study demonstrated that Trad-MCN was sensitive and efficient in evaluating the genotoxicity of organic compounds from biomass burning. It further emphasizes the importance of performing chemical analysis, because changes in chemical composition generally have a negative effect on many living organisms. This bioassay (ex situ), using T. pallida with chemical analysis, is thus recommended for characterizing the genotoxicity of air pollution.

AbstractIsoprene dominates global non-methane volatile organic compound emissions, and impacts tropospheric chemistry by influencing oxidants and aerosols. Isoprene emission rates vary over several orders of magnitude for different plants, and characterizing this immense biological chemodiversity is a challenge for estimating isoprene emission from tropical forests. Here we present the isoprene emission estimates from aircraft eddy covariance measurements over the Amazonian forest. We report isoprene emission rates that are three times higher than satellite top-down estimates and 35% higher than model predictions. The results reveal strong correlations between observed isoprene emission rates and terrain elevations, which are confirmed by similar correlations between satellite-derived isoprene emissions and terrain elevations. We propose that the elevational gradient in the Amazonian forest isoprene emission capacity is determined by plant species distributions and can substantially explain isoprene emission variability in tropical forests, and use a model to demonstrate the resulting impacts on regional air quality.