The optical-microphysical characteristics of smokes from forest combustible materials with different contributions of flaming and smoldering combustion of biomass with 48-h ageing under dark conditions have been studied in the Big Aerosol Chamber of the Institute of Atmospheric Optics (IAO). The dynamics of spectral dependences of aerosol extinction coefficients at wavelengths of 0.45-3.9 µm, scattering and absorption coefficients at 0.46-0.63 µm, aerosol extinction, scattering, and absorption Angstrom exponents, Black Carbon (BC) mass concentration and relative BC content, and single scattering albedo was analyzed. Characteristics of model smokes have been compared with data for smoke plumes from remote Siberian wildfires to assess the mean values of the parameter of mixture of flaming/smoldering modes closest to the actual pattern of absorption properties of remote wildfires. A system for imitation of solar UV irradiation have been deployed in the Big Aerosol Chamber (BAC), and test experiments on generation of secondary organic aerosol under UV irradiation of the near-surface air pumped into BAC have been conducted.
Chemical kinetic model describing the mechanism of the formation of aldehydes and the nuclei of the solid phase in the oxidation of biogenic isoprene was built on the basis of airborne measurements of aldehyde concentrations over the forests of West Siberia. It is demonstrated that the high formaldehyde concentrations at an altitude of 4 km and above are due to the photooxidation of hydrocarbons during the vertical transport from the surface. The contribution of aldehyde photonucleation into the formation of organic atmospheric aerosol is evaluated.
We describe the new procedure developed to determine the functional groups on the surface of nanoparticles formed in photonucleation of furfural, one of the aldehydes generated during forest fire events. The procedure is based on the detection of nanoparticle rupture from chemically modified surface of the quartz crystal microbalance oscillating in the thickness shear mode under voltage sweep. The rupture force is determined from the voltage at which the rupture occurs. It depends on particle mass and on the affinity of the surface functional groups of the particle to the groups that are present on the modified QCM surface. It was demonstrated with the amine modification of the surface that the nanoparticles formed in furfural photonucleation contain carbonyl and carboxyl groups. The applicability of the method for the investigation of functional groups on the surface of the nanoparticles of atmospheric aerosol is demonstrated.
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