微生物氧化作用对有机烷烃气碳同位素的影响

Influence of Microbial Oxidation on δ^(13)C Values of Hydrocarbon Gases

微生物对烷烃气的氧化作用可分为有氧氧化作用和厌氧氧化作用两种类型,均可导致烷烃气组分碳同位素值变重。微生物对烷烃气组分的氧化具有优选性,一般而言丙烷优先于乙烷、正构烷烃优先于异构烷烃被氧化,并得到热力学及厌氧环境中微生物培养实验两方面的证实。微生物氧化作用的优选性导致碳同位素系列发生部分倒转,但烷烃气组分含量并不一定发生倒转。但在某些氧化环境中,也存在乙烷优先于丙烷氧化的现象,这说明微生物在有氧环境中降解烷烃气的机理不同于厌氧环境,或者是微生物种类的不同导致烷烃气组分发生氧化的优先次序发生了变化。

Microbial oxidation of hydrocarbon gases can be divided into aerobic type and anaerobic type. Both of them can result in the enrichment of δ13C values of alkane gases. Some of the gaseous hydrocarbon components show priority during microbial oxidation. In general, propane and n-alkanes are usually preferentially oxidized as compared to ethane and iso-alkanes, respectively. And this has been confirmed by thermodynamics and culture experiments in anaerobic environment. Microbial oxidation can lead to partially reversed δ13C order, while component order does not reverse necessarily. But in some oxidation environments, ethane can be oxidized prior to propane. This means that the oxidation mechanism of aerobic oxidation is different from that of anaerobic oxidation or different type of microorganisms may lead to the change of priority during microbial oxidation.