Volatile hydrocarbons from the burning of grass and straw
The concentrations and proportions of 15 alkenes, 5 alkadienes and 14 other gaseous combustion-formed hydrocarbons were determined near to a controlled field burning of last year´s grass. Small-scale model burning of grasses and of barley straw indicated similar hydrocarbon proportions for all these biomass fuels. Samples were taken on triple-layer adsorbent cartridges and were analyzed, after thermal desorption, by gas chromatography on an aluminium oxide column.
The observed proportions of ethene (20-50%) and ethyne (5-20%) increased for flaming fire and decreased for smouldering. Approximate proportions of prominent genotoxic hydrocarbons other than ethene were 10% benzene, 10% propene, and 3% 1,3-butadiene. Among the photochemically reactive C4-C8 alkenes, the unbranched 1-alkenes were the most prominent isomers. It is concluded that grass burning implies hazards with respect to human exposure as well as to photooxidant formation.