The impact of urban emissions from Manaus and natural biogenic emissions from the Amazon forest in the composition and concentrations of volatile organic compounds and its reactivity in the atmosphereAbstractIn a large part of Amazonia aerosol and trace gases composition is controlled by the vegetation trough still unknown biosphere-atmosphere interactions. The forest biology controls the emission of Volatile Organic Compounds (VOCs) and directly emitted aerosol particles. Besides, the interaction of the anthropogenic emissions of a city like Manaus has an important role on the natural physical and chemical balance of the atmosphere, due to high mixing ratios of NOx, sulfate and VOCs from vehicular sources. The GoAmazon experiment seeks to understand com aerosol and cloud life cycle are influenced by the pollutant transport from Manaus into unperturbed tropical forest. An accurate characterization of the role of biogenic, anthropogenic emissions and subsequent atmospheric reactivity is only possible through the real-time quantification of a large range of VOCs. VOCs from biogenic origin (BVOCs) also have a crucial role on the oxidant concentrations which control the half-life of some greenhouse gases, among them the OH radical. Furthermore, recently has been suggested that aerosols associated with BVOCs have a direct radiative forcing of -0.9 W m-2, in some cases in the same magnitude as the radiative forcing of CO2, but with an opposite sign. VOCs also may affect air quality through chemical reactions that lead to ozone production. Furthermore, strong evidences suggest that VOCs such as toluene and benzene play a crucial role on the production of secondary organic aerosols (SOA).We intend to study the chemical evolution of VOCs and trace gases in the various GoAmazon sites, especially in Iranduba, entitled T2 in the GoAmazon project, located directly downwind of Manaus. Relevant VOCs such as isoprene, monoterpenes, sesquiterpenes, of biogenic origin, and benzene, toluene, C8 and C9 aromatics, on anthropogenic origin, just to cite a few, are to be monitored with high precision. Measurements are to be performed for two years, from January 2014 to January 2016. The composition and temporal variability will be compared then to ozone, NOx, CO, CO2 among others. Such meausurements will be fundamental on the GoAmazon project due to its characterization of the urban impact with little processing. We will also analyze on this project the chemical composition of trace gases on the other GoAmazon sites, e.g., at the ZF2 site (called T0, upwind of Manaus) and further downwind (Manacapuru, T3 site). The instrumentation involved on this study is the Proton-Transfer-Reaction mass spectrometer (PTR-MS), a state-of-the-art system for VOC measurements with a detection limit in the order of 10-12 mol/mol and high temporal resolution, up to 0.1 s. It is also expected GC-MS measurements to be performed at the different GoAmazon site in a rotation basis for validation of chemical speciation of isomers compounds, impossible to separate only through PTR-MS technology. The chemical reactivity curves of the VOC-NOx-ozone will be determined for the several GoAmazon sites (T0, T2 and T3), a crucial information for the Amazonian atmospheric chemistry. The results of this project will allow the interpretation of the chemical characterization of the VOC-NOx-Ozone system and also the physical-chemical characterization of organic aerosols and other gases to a detailed level, fundamental for a study of this magnitude closing the gap between gas and particulate phase organics in Amazonia.
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