Gentoxizität von Dieselmotoremissionen bei Verbrennung von Pflanzenölen, Mineralöldiesel und deren Mischkraftstoffen

Abstract

High particle emissions and strong mutagenic effects were observed after combustion of vegetable oil in diesel engines. This study tested the hypothesis that these results are affected by the amount of unsaturated or polyunsaturated fatty acids of vegetable oils and that blends of diesel fuel and vegetable oil are mutagenic. Three different vegetable oils (linseed oil, LO; palm tree oil, PO; rapeseed oil, RO), blends of 20% vegetable oil and 80% diesel fuel (B20) and 50% vegetable oil and 50% diesel fuel (B50) as well as common diesel fuel (DF) were combusted in a heavy duty diesel engine. The exhaust was investigated for particle emissions and its mutagenic effect in comparison to emissions of DF. The engine was operated using European Stationary Cycle. Particle mass was determined gravimetrically while mutagenicity was determined using the bacterial reverse mutation assay with tester strains TA98 and TA100. Combustion of LO caused the largest amount of total particulate matter (TPM). In comparison to DF it particularly raised the soluble organic fraction (SOF). RO presented second highest TPM and SOF, followed by PO which was scarcely above DF. B50 revealed the lowest amount of TPM while B20 reached as high as DF. RO revealed the highest number of mutations of the vegetable oils closely followed by LO. PO was less mutagenic, but still induced stronger effects than DF. B50 showed higher mutagenic potential than B20. While TPM and SOF were strongly correlated with the content of polyunsaturated fatty acids in the vegetable oils, mutagenicity had a significant correlation with the amount of total unsaturated fatty acids. Vegetable oil blends seem to be less mutagenic than the pure oils with a shifted maximum compared to blends with biodiesel and DF. This study supports the hypothesis that numbers of double bounds in unsaturated fatty acids of vegetable oils combusted in diesel engines influence the amount of emitted particles and the mutagenicity of the exhaust. And the peak of mutagenicity shifts in blends with vegetable oil. Further investigations have to elucidate the causal relationship and where the maximum of the blends lays.