Polycyclic Aromatic Hydrocarbon Emissions and Mutagenicity Assessment of Exhaust from a Diesel Generator

Abstract

Diesel fuel and diesel exhaust are known to be highly mutagenic partly because of the presence of polyaromatic hydrocarbons (PAHs) and their derivatives. The present study investigated the PAHs content in the diesel fuel fed to a diesel generator and also in the gas and particulate phase of generator emissions. Mutagenicity of the exhaust was also determined. Exhaust emissions were collected by a stack sampler: gas phase on XAD-2 resin while particulate phase on glass fibre thimble. PAHs were characterized by a gas chromatograph by using a flame ionization detector. The low molecular weight PAHs dominated in the fuel, whereas the high molecular weight PAHs dominated in the exhaust with a greater emission factor in the particulate phase. The results reveal the pyrosynthesis of high molecular weight PAHs during the combustion process. Emissions also increased with increase in load. Extract of exhaust emissions were positive in both Salmonella typhimurium tester strains TA 98 and TA 100 without metabolic activation, suggesting the presence of direct mutagens that can cause both frame-shift and base-pair mutation. The mutagenic response was greater for TA 100 than TA 98, suggesting greater activity for base-pair mutagenicity than frame-shift mutagenicity. Mutagenic activity increased with the increase in load.