听力文摘：科学家用远古贝壳了解过去（在线收听）

Scientists Use Ancient Shells To Learn About The Past

科学家用远古贝壳了解过去

If you were traveling from the United States to Singapore, a guide book could tell you what sort of climate to expect. But if, like paleontologists and geologists, you needed to know what the weather was like in Singapore tens of millions of years ago, you’d have to consult a different source.

如果你从美国到新加坡旅行，一本指南能告诉你会有什么样的天气。但是，如果你是古生物学家和地质学家，需要知道几千万年新加坡的天气是怎么样的，你得去别的原始资源找寻。

By examining the chemistry of shell fossils, researchers can discover what temperatures were like in ancient climates.

通过研究贝壳化石的化学物质，研究者能够知道在古气候时天气是怎样的。

Oxygen provides the key to finding out about ancient temperatures. Oxygen comes in two different forms—heavy and light. By determining the ratio of the two different types of oxygen in the fossils, researchers can make an educated guess at the temperature of the environment the animals lived in.

氧气是发现原始天气的关键。氧有两种不同的形式——重的和轻的。通过决定在化石中两种氧气的比例，研究者对动物生长环境做出有根据的推测。

Both types of oxygen are found in carbon dioxide, which is found both in the atmosphere and in water. The amount of carbon dioxide water contains depends on the temperature of the water. Cooler water contains more carbon dioxide.

两种形式的氧气都能在二氧化碳中发现，还可以在空气和水中发现。水中含有二氧化碳的量取决于水的温度。比较冷的水含有更多的二氧化碳。

But as the water warms, carbon dioxide gas escapes. Carbon dioxide made of the lighter oxygen escapes at cooler temperatures, leaving more carbon dioxide made of the heavy oxygen in the water. At warmer temperatures, carbon dioxide made of heavy oxygen begins to escape, leaving less heavy oxygen in the water.

但是当水热起来了，二氧化碳会消失。由轻氧构成的二氧化碳在较冷天气下会消失，剩下更多的由水中重氧组成的二氧化碳。在温暖的天气下，由重氧构成的二氧化碳开始消失，剩下不重氧在水中。

Since animals living in the ocean use the carbon and oxygen that remains in the water to build their shells, the shells of animals that lived in a cool climate contain more heavy oxygen.

自从在海边生存的动物使用仍然在水中的氧气和二氧化碳去建它们的贝壳，在凉爽气候下生存壳类动物蕴含更多的重氧。

By grinding up the shells and determining how much of each type of oxygen they contain, researchers can learn what temperatures were like in ancient environments.

通过磨碎贝壳和测试每种氧它们富含多少，研究人员能够了解到在古环境下天气是什么样的。