Title:Massive Volcanic Eruptions Millions of Years Ago Caused Oxygen Shortage in Oceans, Prompting Mass Extinction

Scientists are already seeing areas of the ocean run out of oxygen, threatening fish in the regions who rely on that oxygen to breathe. They think the problem may get worse as the climate continues to change, but it's difficult to know exactly what consequences a massive oxygen shortage could have on the ocean. Because of this, a team of scientists recently looked to pin down exactly what happened to ocean oxygen levels during a volcano-induced period of climate change that took place about 183 million years ago.

科学家已经部分海域海水缺氧，威胁着该海域依赖氧气呼吸的鱼。他们认为，随着气候的持续变化，问题可能会变得更糟，但是很难确切地知道缺氧对海洋可能产生什么后果。为此，一个科学家小组最近试图研究大约1.83亿年前，火山导致的气候变化时期，海洋的含氧量。

The time period, called Toarcian, is also associated with a wave of extinction in marine animals, which raised scientists' suspicions about oxygen levels. Now they've found chemical evidence for the shortage, according to a new study published in the journal Proceedings of the National Academy of Sciences.

这一时期被称为Toarcian，期间有大规模海洋动物灭绝，这引起了科学家对当时的氧气水平产生怀疑。根据在《国家科学院学报》上发表的一项新研究，他们现在已经找到了当时海洋缺氧的化学证据。

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The study's results suggest oxygen shortages are just as big a problem as the other issues facing the oceans. "We used to think of ocean temperature and acidification as a one-two punch," co-author Theodore Them, a geochemist at Florida State University, said in a press release. "But more recently we've learned this third variable, oxygen change, is equally important."

该研究的结果表明，海洋缺氧问题与其他海洋问题一样严重。佛罗里达州立大学的地球化学家Theodore Theon 在一份新闻稿中说：“我们过去曾将海洋温度和酸化视为最重要的问题。“ 但最近我们已经了解到第三个变量 , 海洋的含氧量，也同样重要 。 ”

In the case of the Toarcian period, the collection of challenges arose from a massive spree of eruptions in what scientists call the Karoo and Ferrar Large Igneous provinces, which now stretch over the southern part of Africa and Antarctica. Those eruptions were powerful enough to cause a serious increase in carbon in the atmosphere.

就Tocarcian时期而言，海洋缺氧是由科学家称Karoo和Ferrar Ignor大省份的大规模火山爆发引起的，这些省份现在遍及非洲南部和南极洲。这些火山爆发非常剧烈，足以导致大气中的二氧化碳迅速增加。

To look at the marine impacts, the team gathered rock samples found in Canada and Germany, which at the time would have been covered by a shallow ocean. Then they isolated the chemical fingerprint of an element called thallium, which let them calculate the oxygen levels at the time.

为了观察海洋影响，小组收集了在加拿大和德国发现的岩样，而这些采样岩石在当时被浅海覆盖。然后，他们分离了被称为邻苯二甲酸的化学成分，以测算当时的氧量。

Two of the study's co-authors hold a fossil sample and a rock core sample used in the research.   Stephen Bilenky

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They saw a steep dip in oxygen starting even a little bit before where scientists have traditionally marked the beginning of the extinctions. That finding fills in the gap between volcanic eruptions and marine extinctions that had been bugging scientists.

他们发现，在科学家传统上标志着灭绝开始的时间点之前，海洋含氧量已经急剧下降。这一发现填补了火山爆发和海洋灭绝之间的空白，这些灭绝事件一直困扰着科学家。

But it also raises concerns that our modern situation will get worse before it gets better. "It's extremely important to study these past events," Them said in the press release. "It seems that no matter what event we observe in Earth's history, when we see carbon dioxide concentrations increasing rapidly, the result tends to be very similar: a major or mass extinction event."

但是，它也使人们担心，现在的情况会在好转之前就会变糟。“研究过去这些事件极为重要，”他在新闻稿中说。"不管我们在地球历史中观察到什么情况，当我们看到二氧化碳浓度迅速增加时，结果往往非常相似：一场重大或大规模的灭绝。