Characterization of soot particles coming from aircraft and ship emissions: unique properties and impact on the atmosphere

International audience ; Numerous field observations and modeling studies show a significant role of aircraft black carbon (soot) acting as ice nuclei in contrail and cirrus formation leading to radiative forcing and climate changes in the upper troposphere/lower stratosphere. Ship emission particles (soot + impurities) can also act as nuclei for the formation of cloud droplets and affect by that means the life cycle and radiative properties of marine stratus clouds at the top of the marine boundary layer. Lastly, in harbor and airport areas these emissions are considered as dangerous pollutants with respect to human health.Even if serious models have been developed to estimate the impact of soot aerosols upon the atmosphere and the health, field and laboratory measurements are still missing with regard to their physico-chemical properties as well as their ice nucleation properties. We present here the sampling, characterization and estimations of environmental effects of soot particles collected at the outlet of an aircraft engine combustor and emitted at the end-of-pipe of marine and river ships. Using several techniques (TEM, SEM, FTIR, EDX, neutron diffusion, …) we determine common and specific features of carbonaceous particles with respect to their morphology, size, microstructure, chemical composition depending on the fuel used and on combustion conditions. Water uptake measurements quantify the hygroscopic level of these particles acting as cloud and ice nuclei in the atmosphere.