【摘要】 微生物降解使有机化合物的稳定碳、氢同位素发生不同程度分馏的研究在有机污染物来源和微生物环境修复等领域取得了长足进展,并对原油和天然气微生物降解研究有借鉴意义。微生物作用下的同位素分馏为动力同位素分馏,导致重同位素在残余物中富集。影响微生物降解有机物同位素分馏的主要因素有微生物的降解代谢途径、辅酶作用、降解类型与程度、同位素质量差异和有机物碳数等。不同的微生物代谢途径代表不同的生物化学反应,造成了同位素分馏的显著差异;辅酶对反应的催化作用使微生物作用造成的同位素分馏更加复杂。低碳数正构烷烃遭受微生物降解程度越高,碳、氢同位素的分馏也越大,同位素变重与降解程度之间有明显的相关性。但对于复杂化合物,由于降解的多级反应,同位素分馏与降解程度间的相关性并不明显。在同样降解程度下,氢同位素分馏大于碳同位素分馏,低碳数正构烷烃的同位素分馏大于高碳数正构烷烃的同位素分馏。更多还原

【Abstract】 The carbon and hydrogen isotopes of organic compounds are fractionated in different degrees during microbial degradation.Quite great progresses have been obtained on this kind of researches in the fields of organic contaminants sources and microbial remediation of environments and can be used as reference in the studies of oil and natural gas biodegradation.The isotopic fractionation under microbial actions belongs to the kinetic isotopic fractionation,which results in the enrichment of heavier isotopes in the remnants.The critical factors that affect the isotopic fractionation of organic compounds under microbial degradation are:the microbial degradative metabolic pathways,enzyme reactions,the types and extent of biodegradation,the difference in the isotopic masses,the carbon number of organic compounds and so on.Different metabolic pathways represent different biochemical reactions and result in significant variations in the isotopic fractionations.The catalysis of enzymes causes much more complexity for the isotopic fractionation under microbial actions.For the low carbon number n-alkanes,the higher the extent of biodegradation is,the larger the carbon and hydrogen isotopic fractionation become,and their enrichment of heavier isotopes are clearly related to the biodegradation degrees.But for the complex compounds,there are no clear relations between isotopic fractionation and biodegradation degrees because of the multilevel reactions of the biodegradation.Under same extent of biodegradation,the hydrogen isotopic effect is larger than that of carbon,and the isotopic fractionations of low carbon number n-alkanes are larger than that of high carbon number n-alkanes.更多还原