古代地球含有更多氧气，超过科学家预料（在线收听）

Ancient Earth Had More Oxygen than Scientists Thought 古代地球含有更多氧气，超过科学家预料

Researchers say the Earth had much more oxygen nearly a billion years ago than scientific experts thought. That claim could change theories about how life developed on our planet.

研究人员称，十亿年前地球的氧气含量比科学家预测的要多。这一论断可能会改写生命在地球上发展的理论。

The claim came from researchers at Brock University in Canada.They wanted to measure the levels of oxygen in the Earth’s atmosphere nearly a billion years ago.To do this, the researchers developed a way to study small air bubbles trapped in ancient salt crystals.

这一论断来自于加拿大布洛克大学的研究人员。他们想要测量十亿年前地球大气中氧气含量水平。为了达成这个目的，他们发明了一种方法来研究古代盐晶中的气泡。

“There was a lot of debate as to what the oxygen content was 800 million or more years ago,”said Nigel Blamey of Brock University’s Department of Earth Sciences.He said the trapped gasses showed that the oxygen level was about half of what it is today.

“关于8亿年前的氧气含量，存在很多争论。”布洛克大学地球科学部的尼格尔·布拉米说。他说，气泡中的气体显示，氧气含量大约是现在的一半。

In fact, many experts believed that the oxygen level was only about two percent of the atmosphere so long ago.But the new study found that it was almost 11 percent.Currently, oxygen is about 21 percent of the atmosphere.

事实上，很多专家认为，很久以前大气中的氧气含量只有现在的2%。但是这项新的研究发现，当时的氧气含量达到了11%。现在大气中氧气的含量约为21%。

The Canadian researchers used a method to study air bubbles trapped in halite, the natural form of table salt.

加拿大研究人员用了一种的方法来研究岩盐中的气泡——岩盐就是精制食盐的自然形式。

The researchers say their findings have major effects for theories about how and when life developed.

研究人员称，他们的发现对生命发展的时间和方式方面的理论有很大的影响。

Professor of Earth Sciences Uwe Brand said that higher oxygen levels in the past may turn back the clock when complex life developed.“Now paleobiologists will have reason to go looking for rocks with evidence of these first evolutionary steps,”he told the Canadian Broadcasting Corporation.

地球科学部教授武威·布兰德说，过去的氧气含量比预料的高，可能意味着复杂生命出现的时间又提前了。“现在古生物学家有理由在岩石中寻找这些进化早期的证据了。”他在接受加拿大广播公司采访时说。

Words in This Story

bubble – n. a small ball of air in a solid substance

crystals – n. small pieces of a substance that has many sides and are formed when the substance turns into a solid

clock - n. an instrument for telling time