The trick they used to do this was to look at the isotopic composition of the oxygen in the wood of local trees.

他们所使用的办法是观测当地树木的木材中的氧同位素组成（isotopic composition）。

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Such a study provides a basis for understanding palaeoclimate shifts by investigation of organic carbon isotopic composition in the deep sea sediments.

从而为利用深海沉积有机质碳同位素组成研究古气候变迁提供了依据。

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Now, by examining the isotopic composition of that water, researchers have found that it matches that of meteorites, the likes of which also delivered Earth its first drink.

现在，通过检查水的同位素构成，研究人员发现这与第一次给地球带来水的陨石相吻合。

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By analysing the isotopic composition of hydrocarbon molecules from plant waxes of the period, he found what looks like a spike in the amount of recently non-biological carbon (which has a distinctive ratio of light isotopes to heavy ones), lasting between 10, 000 and 20, 000 years.

ECONOMIST: A geological burp may have led to the dinosaurs�� domination