Elemental composition of combustion emissions from spark ignition vehicles

Abstract

In petrol engines, solid particle phases are formed as a result of incomplete combustion. In emissions from combustion processes such as petrol, natural gas or diesel, concentration of particles smaller than 1 µm could be several orders of magnitude higher than those which are larger than 1 µm. Due to their physical properties, submicrometer particles have a high probability of deposition in the deeper parts of the respiratory tract. It is known that petrol particles are mutagenic and carriers of hydrocarbons (and other compounds) adsorbed on the particulate and as a result represent a serious health hazard if inhaled. The present paper reports on some measurements of particle size distribution and composition of the bulk aerosol, as well as on morphological and elemental information from individual particles. The study was performed on non-diluted petrol exhaust obtained under different engine operation conditions. The bulk aerosol chemistry study has been performed. The concentrations of the following trace elements were measured: Boron, Calcium, Titanium, Chromium, Manganese, Iron, Cobalt, Nickel, Copper, Zinc, Cadmium, Barium, and Lead. The petrol particles have been found to be spherical. The most abandon elements were Fe, Ca, and Zn that have their origin from the additives in lubricating oil. It is interesting to note that although particle concentrations increased for 3 orders of magnitude from 40 to 120 km/h, emissions of metals did not significantly increase. This would indicate that most of the particle emission at higher loads comes from the unburned fuel and consists mainly of carbon either in elemental or organic form.