Going underground

A project to reveal more about all the carbon on Earth
旨在向人们揭示更多地球碳信息的项目

The Deep Carbon Observatory
深碳观测站

Feb 24th 2011 | from the print edition

A world still full of secrets
一个依然充满秘密的世界

THE carbon cycle is the stuff of school books. It is a familiar tale of photosynthesis, forests, farming and fossils fuels. Understanding this cycle is important, both because it sustains life on Earth and because it is bound up with the rate of global warming. But are the outlines of the carbon cycle really that familiar?

碳循环是学校书本上的东西。这是个关于光合作用、森林、耕作以及化石燃料的熟识的故事。理解这种循环很重要，不仅因为碳循环维持地球上的生命，而且因为它对于全球变暖的速度有密切关系。不过关于碳循环的概要，我们真的那么熟悉吗？

At the AAAS meeting in Washington, DC, Robert Hazen of the Carnegie Institution for Science, which is based in the same town, gave a lecture intended to show that this view of the carbon cycle only scratches the surface. Dr Hazen is one of the moving spirits behind a project called the Deep Carbon Observatory, which will be paid for by the Alfred P. Sloan Foundation. Over the course of the next decade it will attempt to understand all the carbon in the Earth, not just the stuff that cycles through the atmosphere, the oceans and living things.

在华盛顿的AAAS会议，来自卡内基科学学院（Carnegie Institution for Science）（同样位于华盛顿）的Robert Hazen发表演讲。该演讲旨在展示上述对碳循环的的看法仅仅触及表面。Hazen博士是被称作深碳观测站项目的幕后策划者，该项目由Alfred P. Sloan基金出资。接下来的十年中，该项目将试着去了解地球上所有的碳，而不仅仅是通过大气、海洋和生物循环的东西。

As Dr Hazen pointed out, carbon is the fourth-most-abundant element in the universe, after hydrogen, helium and oxygen. In the Earth, though less common than that, it is reckoned to make up between 0.07% and 3.2% of the planet. But the uncertainty of this range is itself a comment on how little carbon's role in the Earth's overall physics and chemistry is understood. Also uncertain is how much interchange there is between the carbon in the Earth's mantle and core, and the more familiar stuff in the crust, atmosphere and oceans.

正如Hazen博士指出的那样，在氢、氦、氧之后，碳是宇宙中第四充足的元素。在地球上，尽管没有宇宙那么常见，据估计有0.07%到3.2%是由碳构成的。这种范围不确定本身就解释了关于碳在地球总体物理、化学中的作用，人们了解的是那么的少。在地球的地幔和地核之间、或者地壳中更为我们熟知的大气和海洋之间有多少碳交换也是不确定的。

Some carbon comes from the mantle to the surface in the form of diamonds. These crystals, which can form only under the intense pressure of the Earth's deep interior, must have been erupted at unbelievable speed (about 100kph) to have survived the journey to the surface intact. At slower speeds they would have turned into graphite, much to the chagrin of brides-to-be everywhere.

一些从地幔到地球表面的碳以钻石的形式存在着。这些晶体只有在地球深处的集中压力下才能形成，必然是以不可思议的速度（100千米/小时）喷发，在通往地球表面的过程中完好无损地幸存下来。与随处可见的准新娘的懊恼一样，稍微慢一点它们就会变成石墨。

How, exactly, diamond forms is an important question. Diamonds are useful as an industrial material as well as gem stones, and they would have many more applications if they could be made cheaply. And another, even more important industrial material, petroleum, may also come from the mantle.

钻石究竟是如何形成的？这是一个重要的问题。和宝石一样，作为工业原料的钻石很有用，而且如果他们价格便宜一些的话会有更多的用处。另外一种更重要的工业原料石油也是来自地幔。

Among petroleum geologists in Western countries, the consensus is that crude oil and natural gas are formed near the Earth's surface from the fossilised bodies of living organisms. Many Russians, though, disagree. They support the 130-year-old idea of their countryman Dmitri Mendeleev (who created the first version of the periodic table of elements). He thought the temperatures and pressures of the mantle would convert carbonates and water into hydrocarbons.

在西方国家的石油地质学家中，原油和天然气是在靠近地表处由生物有机体的硬化部分而来。然而许多俄国人不同意这点。他们支持他们同胞门捷列夫（他创造了元素周期表的第一版）有130年历史的观点。门捷列夫相信，地幔的温度和压力会把碳和水转变成碳氢化合物。

That has, indeed, been done experimentally in the past. And one role of the Deep Carbon Observatory will be to try to do it again in more sophisticated ways. If it turns out that fossil fuels are abiogenic, that probably means they are more abundant than Western geologists think, and may be found in places hitherto thought unpromising.

实际上，在过去的试验中见证了这点。而深碳观测站的一个作用就是用更加复杂的方式来尝试重新做这种试验。如果试验证明化石燃料并非由生物体产生，那可能意味着它们比西方地质学家想象的还要多，而且可能会在迄今为止被认为没有希望的地方发现。

Abiogenic petroleum could also provide food for one of the most intriguing targets of all for the Deep Carbon Observatory: the bacteria that live in the Earth's depths. Current estimates suggest that half of all the living matter on Earth lives underground, at depths of up to 5km. Some people think the share may be bigger than that. Indeed, there is loose talk of life having originated more than once in the distant past, and of there being entire shadow biospheres of organisms completely unrelated to anything on the surface.

并非由生物体产生的石油也许可以为深碳观测站最令人感兴趣的目标提供食物：在地球深处生活的细菌。最近估计表明，地球上的半数生物在深达5千米的地下生活。一些人认为这一比例数字可能还可以再大一些。实际上，关于在遥远的过去生命起源不止一次，以及完全与地表任何东西无关联的少量有机体生物圈的存在，这都是胡说八道。

Intriguingly, a few diamonds bear signs that their carbon was once part of living organisms. The ratio between the heavy and light isotopes of the element in their crystals is not quite right for stuff that has come out of the ground. Instead, it matches the ratio found when organic molecules have been through a few rounds of biochemical processing. Clearly there is a lot going on deep in the Earth that is completely unknown to science. With a bit of luck, over the ten years of Dr Hazen's project, the veil of ignorance will be lifted a little.

有趣的是，一些钻石具有这样的迹象：它们的碳曾经是生物有机体的部分。它们晶体内元素的轻重同位素的比例与那些来自地表的东西不完全吻合。相反，与经历几轮生物化学过程的有机体分子中的比例匹配。显然，地球深处发生了许多科学完全未知的事儿。Hazen博士今后10年多的项目研究，加上一些运气，无知的面纱将会揭开一点点。

水平有限，请多多指教。