Search

In this article, a model which examines the evolution of ion concentrations in a hot aircraft exhaust plume on the ground is proposed. The model includes plume dilution and ion-ion recombination with coefficients which vary with temperature. A comparison of the model is made with the available ground-based experimental data obtained on the ATTAS research aircraft engines. From this comparison, an ion emission index of the order of 8-10 16 ions/kg(fuel) is inferred.

The density and surface tension of the H2SO4/HNO3/H2O ternary system have been measured as a function of temperature from 245 to 298 K. The acid compositions range from 0 to 65 wt % for sulfuric acid and 0 to 45 % for nitric acid. The densities and surface tensions for the ternary system, combined with the data for the two binary mixtures water/nitric acid and water/sulfuric acid have been expressed as polynomials of the nitric acid and sulfuric acid weight % for the temperatures of 253 and 293 K. Since the densities and surface tensions vary linearly with temperature, data at temperatures other than 253 and 293 K can easily been obtained by interpolation.

The uptake of nitryl chloride ClNO2 by pure water and NaI solutions was studied as a function of temperature in the range from 268 to 279 K with the droplet train technique. An upper limit of 10−5 was derived for the uptake on pure water, while the uptake rate was observed to be greatly enhanced in the presence of 10−3–10−2 M iodide, yielding uptake coefficients in the range from 1.1 × 10−3 to 6.6 × 10−3. This enhancement is a consequence of a reaction between I− and ClNO2 where we suggest that a transfer of Cl+ to iodide is involved. We also suggest that bulk kinetics alone is unable to describe the measured uptake rate which is influenced by surface reactions. These results show that heterogeneous chemistry in concentrated aerosols may play an important role for the fate of ClNO2, and may affect the concentration of atomic chlorine in the marine boundary layer.