Sulfuric acid and soot particle formation in aircraft exhaust

Abstract

Size analyses of Ames wire impactor aircraft exhaust aerosol samples resulted in a continuous particle size distribution between 0.01 µm and 1.0 µm particle radius. The two orders of magnitude size range covered by the measurements correspond to 6–7 orders of magnitude particle concentration. The data determined a nucleation mode, composed of aircraft‐emitted sulfuric acid aerosol, that contributed between 62% and 85% to the total aerosol surface area and between 31% and 34% to its volume. Soot aerosol contributed 0.3% to the surface area and 0.07% to the volume of sulfuric acid aerosol. Emission indices were: EI H2SO4 =0.09 g/kg FUEL and (0.2‐0.5) g/kg FUEL (for 75 ppmm and 675 ppmm fuel‐S, respectively), 1.7E‐4<EI SOOT <1.3E‐3 g/kg FUEL , and EI N>0.01 =1.7E14 and (7.7E14 and 5.2E15) particles/kg FUEL (for 75 and 675 ppmm fuel‐S, respectively). The sulfur (gas) to sulfuric acid (particle) conversion efficiency was between 10% and 37%.