Composition of carbon and oxygen isotope indicates that origin of carbon comes from mixture of the crust and mantle.

碳、氧同位素组成指示碳来源于壳幔混合。

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The research of carbon isotope of methane has important significance for the clarification and origin of the coal-formed gas as well as for the resource estimation.

甲烷碳同位素的研究对煤成气的分类、成因及资源评价均有重要意义。

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This paper gives a discussion on the origin of natural gas in the shallow reservoir in Binhai area, by a study of light hydrocarbons (C_1-C_7) and carbon isotopes.

本文利用轻烃(C_1—C_7)和碳同位素分析资抖，对滨海地区浅层天然气成因进行探讨。

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Such an approach makes fuel and feedstock production facilities the focus of accounting, he suggests, while treating the CO2 emissions from fuel end-use at face value regardless of the origin of the fuel carbon (bio or fossil).

FORBES: Rethinking Life-Cycle Fuel Regulations