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Posters-Accepted Abstracts: J Chromatogr Sep Tech
Emission of carbon from ecosystems in the form of volatile organic compounds (VOC) represents a minor component flux in the global carbon cycle that has a large impact on ground-level ozone, particle and aerosol formation and thus on air chemistry and quality. Moreover, combustion of solid and liquid fuels is the largest source of potentially toxic VOC, which can strongly affect health and the physical and chemical properties of the atmosphere. Among combustion processes, biomass burning is one of the largest at global scale. We used a Proton Transfer Reaction �??Time-of-Flight�?� Mass Spectrometer (PTRTOF- MS), which couples high sensitivity with higher mass resolution, both in combination with the eddy covariance method to measure by-directional fluxes of VOC in a poplar-based short rotation coppice (SRC) plantation, and for real-time detection of a multiple VOC emitted by burned hay and straw in a barn located near our measuring station. Whereas abundant fluxes of isoprene, methanol and, to a lesser extent, fluxes of other oxygenated VOC such as formaldehyde, isoprene oxidation products (methyl vinyl ketone and methacrolein), methyl ethyl ketone, acetaldehyde, acetone and acetic acid, were exchanged between the poplar plantation and the atmosphere, we detected 132 different organic ions directly attributable to VOC emitted from the fire. Methanol, acetaldehyde, acetone, methyl vinyl ether (MVE), acetic acid and glycolaldehyde dominated the VOC mixture composition. The time-course of the 25 most abundant VOC, representing ~ 85% of the whole mixture of VOC, was associated with that of carbon monoxide (CO), carbon dioxide (CO2) and methane (CH4) emissions. The strong linear relationship between the concentrations of pyrogenic VOC and of a reference species (i.e. CO) allowed us to compile a list of emission ratios (ERs) and emission factors (EFs), but values of ER (and EF) were over estimated due to the limited mixing of the gases under the stable (non-turbulent) nocturnal conditions. In addition to the 25 most abundant VOCs, chemical formula and concentrations of the residual, less abundant VOCs in the emitted mixture were also estimated by PTR-TOF-MS. Furthermore, a time-resolved evolution of the complex combustion process was described on the basis of the diverse types of pyrogenic VOCs recorded.