Development of simplified soil pollution evaluation method using luminous bacteria for petroleum hydrocarbons 3 -Acute toxicity evaluation of alkane structural isomers-

Abstract

For the purpose of developing a simplified soil pollution evaluation method using luminous bacteria for petroleum hydrocarbons, in the previous study, the acute toxic effects of n-alkanes which are the main components of gasoline were evaluated. On the other hand, many petroleum hydrocarbon products such as gasoline also contain many branched alkanes. In this study, to investigate the differences in toxic effects due to differences in molecular structure, acute toxicity tests using luminescent bacteria was conducted with structural isomers of chain alkanes (2 types of pentane and 5 types of hexane) and a cyclic alkane (cyclohexane). The alkane structural isomers dissolved in methanol were used as test solutions. Then magnitude relationship of the acute toxicity were 2-methylbutane ＜n-pentane ＜ 2,2-dimethylbutane ＜ Cyclohexane ＜ 3-methylpentan ≦2,3-dimethylbutane ≦2-methylpentane ＜ n-hexane, based on the estimated value of the alkane concentration at which the relative luminescence intensity ratio at the reaction time of 60 minutes becomes 50%. Comparison of the test results for the structural isomers indicated that the acute toxicity of the straight chain alkanes is higher than that of the branched chain ones. In addition, this study suggested that the acute toxicity might increase with increasing number of carbon atom in the straight chain.