Volatility of secondary organic aerosol and sulphate particles formed in ship engine emission

Abstract

The secondary organic aerosol formation potential of a ship engine emission is assumed to be significant since ship engines are known to emit large amounts semi- and intermediate volatility organic compounds capable of forming secondary organic mass in the atmosphere. However, this is poorly studied in real-world conditions. Here, oxidation reactor was used to simulate atmospheric aging of an exhaust emission aboard a ship in real-world conditions. The samples were also heat-treated to gain information on the volatility of the aged emission. Genetic optimization algorithm was combined with a volatility model to study the volatility distribution of the emission and partitioning of the emission was calculated in different dilution scenarios. Aging of the ship exhaust emission was seen to produce significant amounts of secondary organic mass and quite volatile particle phase sulphate. Most of the secondary organic aerosol was in semi- and intermediate volatility range. This volatility range in particle phase means that care has to be taken when diluting the samples. The gas–particle phase partitioning of volatile material can significantly change the particle phase concentrations in addition to just dilution.