FORMATION OF MUTAGENS IN FUEL-RICH TURBULENT-DIFFUSION FLAMES OF NATURAL-GAS AND COAL-LIQUID FUEL

Spatial distributions of polycyclic aromatic compound (PAC) concentrat ions were determined in industrial-scale turbulent flames of natural g as and a liquid synthetic-coal fuel. Samples extracted from the flames with dichloromethane were submitted to bacterial mutation assays. The chemical analysis of the gas-flame samples showed, in agreement with previous studies, pyrosynthetic formation and inter-conversion of PAC, resulting in growth of molecular weight along the length of the pyrol ysis flame zone, and leading to the formation of soot. However, cyclop enta(cd)pyrene-a known mutagen-was found to break the general trend of PAC interconversion: it began to form late in the pyrolysis process, and grew in parallel with soot. Bacterial mutation assays of the flame samples showed the mutagenicity per gram of material extractable by d ichloromethane to rise with the fraction of 4- or 5-ring aromatic comp ounds in the sample, and the mutagenicity per unit energy input to be proportional to the gas-phase PAC concentration. It appears that for p urposes of control of mutagens emission from practical plant, the moni toring and control of the sum of the PAC concentrations would suffice.