生命的诞生：解开古老火山的谜团 To unravel the mystery of ancient volcanoes

生命的诞生：解开古老火山的谜团 To unravel the mystery of ancient volcanoes
Nearly 80% of Earth's atmosphere is nitrogen gas, which is two nitrogen molecules stuck together by not one, not two, but three chemical bonds.
地球的大气层中，大约有80%是氮气，由两个氮分子通过三个化学键紧密结合而成，而不是一个或两个。
And this molecule is pretty inert, so most organisms can't do a single thing with it.
而这种分子极其稳定，因此绝大多数生物体无法对它进行任何处理。
That means nitrogen has to be fixed, or chemically converted into a different form, before it becomes useful to an ecosystem.
这意味着，在氮气对生态系统有益之前，必须先将其固定或化学转化成另一种形态。
Humans can do this in factories, and we do a lot of it when we make synthetic fertilizers.
人类能够在工厂中完成这一过程，并且在生产合成肥料的时候，我们进行了大规模的生产。
But in the non-manmade nitrogen cycle, it happens in two ways.
但在自然的氮循环中，这一过程通过两种方式进行。
Lightning can fix a tiny bit of atmospheric nitrogen by breaking apart the bonds between the two nitrogen atoms with immense amounts of energy as it rips through the sky.
当闪电划破天际，以巨大的能量断裂两个氮原子间的键合时，能够修复一小部分大气氮。
And those free nitrogen atoms bond with oxygen to make nitrogen oxides, which fall to the earth with rain.
而这些自由态的氮原子会与氧结合形成氮氧化物，伴随雨水降落到地球表面。
But lightning fixes only about 1% of all the nitrogen made available to organisms each year.
但闪电每年仅能使大约1%的氮变得可供生物体利用。
The vast majority of nitrogen fixing is done by single-celled organisms like bacteria and archaea, which have evolved a way to drive a wedge between those stubborn triple bonds.
固定氮素的主要工作是由像细菌和古菌这样的单细胞生物完成的，它们进化出了一种分解坚固的三键氮分子的方式。
Microorganisms in the soil and on the roots of certain plants convert N2 in the air to ammonia, which is further converted by different bacteria into nitrate and nitrite, which can be used by plants and other primary producers to be shuttled on up the food web.
土壤和某些植物根际的微生物把空气中的N2转换成氨，随后不同的细菌将其进一步转化为硝酸盐和亚硝酸盐，供植物及其他初级生产者使用，并通过食物网向上输送。
This brings up an interesting chicken and egg question: which came first, the bioavailable nitrogen or the nitrogen-fixing microbes?
这提出了一个有趣的问题：是先有可被生物利用的氮，还是先有固氮微生物呢？
Well, it's not quite chicken and egg, because it's generally agreed that the nitrogen fixation that seeded the first life on Earth must have occurred through non-biological means.
其实，这并不完全像是鸡生蛋还是蛋生鸡的问题，因为人们普遍同意，地球上第一个生命的诞生必然伴随的固氮作用，肯定是通过了非生物的方式来实现的。
It's just been incredibly unclear how.
只是非常不清楚这是如何发生的。
So theories abound.
因此，各种理论层出不穷。
The problem is that geological evidence to support any of them doesn't.
问题是，没有任何地质证据能够支撑这些理论。
For instance, some models suggest N2 was belched into our planet's early atmosphere by volcanic eruptions, and then lightning and frequent meteorite strikes converted it to nitric oxide, which would have reacted with light and water to produce nitrate and nitrite.
例如，有些模型推测，N2是由火山爆发释放到我们地球早期大气中的，随后闪电和频繁的陨石撞击使其转化成一氧化氮，一氧化氮再与光和水反应，生成硝酸盐和亚硝酸盐。
The problem here is, this would have taken ages.
问题在于，这个过程将会持续极长的时间。
By some estimates, this method would have resulted in nitrogen fixation happening anywhere between 50 to 5000 times slower than what we see today.
据估计，这种方式进行的氮固定速度可能是我们今天观察到的速度的50至5000倍之慢。
It's also been suggested that atmospheric nitrogen could have been converted to ammonium if it reacted with iron, magnetite or iron sulfide minerals under high temperatures in the vicinity of hydrothermal vents.
也有观点认为，大气中的氮气如果在热液喷口附近的高温条件下与铁、磁铁矿或硫化铁矿反应，有可能被转换成铵盐。
But no one's observed that actually happening.
但实际上并未有人观察到这一现象的发生。
So there are other less likely theories about how the early Earth's nitrogen cycle got its start, but many researchers think electrical discharges from lightning is kind of the only thing it could have been.
因此，虽然还存在其他一些不太可能的理论来解释地球早期氮循环的起源，但很多研究者认为，来自闪电的电放电或许是最为合理的解释。
But if thunderstorm lightning isn't enough, then what?
但如果雷暴中的闪电不足以解释，那么还有什么解释呢？
One team of researchers has presented evidence that lightning is what did it, thanks to volcanic eruptions.
一支研究团队已经提出证据，正是闪电造成了这一结果，而这得益于火山爆发。
Volcanoes can make a lot of lightning, caused by little bits of rock and ash bumping into each other and electrifying inside the volcanic plume.
火山能够产生大量的闪电，原因是火山灰和碎石在火山羽流中互相碰撞并产生电荷。
One 2022 eruption produced 400,00 lightning strikes in just 6 hours.
2022年的一场喷发在短短六小时之内就产生了四十万次闪电。
In a 2024 paper in the journal PNAS, the team suggested that massive volcanic eruptions on the early Earth could have fixed a bunch of nitrogen.
2024年发表于《美国国家科学院院刊》的一篇论文中，研究团队提出，早期地球上的大型火山喷发可能导致了大量氮气的固定。
That means primordial volcanoes were the nurseries of the earliest version of Earth's nitrogen cycle.
这表明，原始火山是地球最初氮循环的发源地。
Kind of by accident, the research team stumbled across the possible solution to the mystery surrounding the origin of Earth's first fixed nitrogen boom.
研究团队几乎是偶然间，发现了解开地球首次固氮繁荣之谜的可能答案。
They were poking around in the volcanic deposits of two long-dead giant volcanoes in Turkey and Peru for a climate study focused on sulfates.
他们正在土耳其和秘鲁两座已灭绝巨型火山的火山沉积物中寻找，这是一项关注硫酸盐的气候研究。
But they noticed that the deposits contained shocking amounts of fixed nitrogen.
但他们发现，这些沉积物中固定氮的含量惊人。
They compared these deposits to those of a much younger, though still huge, eruption in Italy to test whether the arid climates or the extreme age of the other volcanoes had made a difference to their nitrogen content.
他们把这些沉积物和意大利一场年纪较轻但同样规模巨大的火山喷发所形成的沉积物做了对比，目的是为了验证干燥的气候或是其他火山极老的年龄是否对其氮含量有所影响。
But no, all the deposits were full of nitrogen.
然而，所有沉积物中的氮含量都非常高。
So where did it come from?
那氮素究竟是从哪里来的呢？
To find out, the researchers tested the isotopic composition of the oxygen, not the nitrogen, in the deposits.
为了解开这一谜团，研究人员检测了沉积物中氧的同位素组成，而非氮素。
They looked at how many neutrons each oxygen atom contained.
他们检查了每个氧原子中包含的中子数量。
Oxygen-containing molecules can originate from almost anywhere, like water or sulfate belched out of the bowels of the earth.
含氧分子几乎可以来源于任何地方，如水里或地球深处喷涌出的硫酸盐。
But the specfic oxygen isotopes in the nitrate and sulfate found in those volcanic deposits could only have come from ozone, which is strictly an atmospheric gas.
但在这些火山沉积物中所发现的硝酸盐和硫酸盐特有的氧同位素，只可能源自臭氧，臭氧是一种严格意义上的大气中的气体。
And that means that the nitrate had to be formed by chemical reactions in the air.
这表明硝酸盐一定是通过空气中的化学反应生成的。
Pretty surprising, considering that the stuff that's belched out of a volcano originates deep in the ground.
挺让人吃惊的，尤其是考虑到那些从火山中喷出的物质，实际上是源自地底深处。
So, the nitrogen must have been fixed by lightning which must have been a lot of lightning, like a sight to behold!
所以，氮气肯定是被雷电固定下来的。这表示肯定有大量的闪电。简直是一道难以置信的美景！
And the research team suggests that a big eruption might fix 60 teragrams of nitrogen, which is like 60 billion kilograms if I'm moving the decimals right, or about 132 billion pounds!
研究团队表示，一次大型爆发可能固定60太克的氮气，折合下来大概是600亿公斤，如果我没把小数点搞错的话，那就是大约1320亿磅！
Thunderstorm lightning could never fix nitrogen on that scale or in one place.
雷暴闪电无法在同一地点以那样的规模固定氮气。
A volcano, though, could provide a huge shot in the arm to the surrounding environment, in addition to other nice minerals that might have been really helpful to kickstart early life.
然而，火山能大幅促进周遭环境的发展，除此之外，它释放的其他有益矿物质也可能对早期生命的起源起到推动作用。
You probably wouldn't have wanted to be anywhere near these volcanic eruptions.
你可能不会想靠近这些火山爆发的地方。
And even if you think you might, the residents of Pompeii would like a word.
即便你想靠近喷发的火山，庞贝的居民恐怕要和你好好谈谈。
But that choking inferno of ash and lightning may be responsible for you, bacteria, plants, and everything alive today.
但那充满窒息感的火山灰和雷电，可能是你、细菌、植物乃至今日地球上所有生命存在的原因。
As if the power of volcanoes didn't command enough respect already.
好像火山的威力还未得到足够的重视似的。【贝贝英语网】