氧氣的發現挑戰了深海知識 (1/2)

Recently Yahoo News on-line reported the following:

Oxygen discovery defies knowledge of the deep ocean (1/2)

BBC - Victoria Gill - Science correspondent

Updated Tue, July 23, 2024 at 6:21 a.m. PDT·4 min read

Scientists have discovered “dark oxygen” being produced in the deep ocean, apparently by lumps of metal on the seafloor.

About half the oxygen we breathe comes from the ocean. But, before this discovery, it was understood that it was made by marine plants photosynthesizing - something that requires sunlight.

Here, at depths of 5km, where no sunlight can penetrate, the oxygen appears to be produced by naturally occurring metallic “nodules” which split seawater - H2O - into hydrogen and oxygen.

Several mining companies have plans to collect these nodules, which marine scientists fear could disrupt the newly discovered process - and damage any marine life that depends on the oxygen they make.

“I first saw this in 2013 - an enormous amount of oxygen being produced at the seafloor in complete darkness,” explains lead researcher Prof Andrew Sweetman from the Scottish Association for Marine Science. “I just ignored it, because I’d been taught - you only get oxygen through photosynthesis.

“Eventually, I realized that for years I’d been ignoring this potentially huge discovery,” he told BBC News.

He and his colleagues carried out their research in an area of the deep sea between Hawaii and Mexico - part of a vast swathe of seafloor that is covered with these metal nodules. The nodules form when dissolved metals in seawater collect on fragments of shell - or other debris. It's a process that takes millions of years.

And because these nodules contain metals like lithium, cobalt and copper - all of which are needed to make batteries - many mining companies are developing technology to collect them and bring them to the surface.

But Prof Sweetman says the dark oxygen they make could also support life on the seafloor. And his discovery, published in the journal Nature Geoscience, raises new concerns about the risks of proposed deep-sea mining ventures.

The scientists worked out that the metal nodules are able to make oxygen precisely because they act like batteries.

“If you put a battery into seawater, it starts fizzing,” explained Prof Sweetman. “That’s because the electric current is actually splitting seawater into oxygen and hydrogen [which are the bubbles]. We think that’s happening with these nodules in their natural state.”

“It's like a battery in a torch,” he added. “You put one battery in, it doesn't light up. You put two in and you've got enough voltage to light up the torch. So when the nodules are sitting at the seafloor in contact with one another, they’re working in unison - like multiple batteries.”

(to be continued)

Translation

科學家發現深海中正在產生“暗氧”，顯然是由在海床的金屬塊產生的。

我們呼吸的氧氣大約有一半來自海洋。但是，在這次個發現之前，人們認為氧氣是由海洋植物光合作用所產生的 - 它是需要陽光來產生。

在這裡，在陽光無法穿透的 5 公里深處，氧氣似乎是由天然存在的金屬「小瘤」產生的，這些金屬「小瘤」將海水 - H2O - 分解為氫氣和氧氣。

幾家採礦公司計劃收集這些小瘤，但海洋科學家擔心這些行動可能會破壞這新發現的氧氣形成過程，並損害任何依賴所產生的氧氣的海洋生物。

蘇格蘭海洋科學協會的首席研究員 Andrew Sweetman 教授解釋道:「我第一次看到這一現像是在 2013 年，海底會在完全黑暗的情況下產生大量氧氣」; 「我就是忽略了它，因為我被教導 - 你只能透過光合作用才獲得氧氣」。

他告訴英國廣播公司新聞:「最終，我意識到多年來我一直忽視了這一潛在的巨大發現」。

他和他的同事在夏威夷和墨西哥之間的深海區域進行了研究，該區域是覆蓋著這些金屬小瘤的大片海底的一部分。當被海水溶解出來的金屬聚集在貝殼碎片或其他碎片上時，就會形成小瘤。這是一個需要數百萬年的過程。

由於這些結核含有鋰、鈷和銅等金屬 - 所有這些金屬都是製造電池所必需的 - 許多礦業公司正在開發技術來收集它們並將它們帶到地面。

但Sweetman教授表示，小瘤產生的暗氧也可以維持海底的生命。他的發現發表在《自然地球科學》雜誌上，引發了人們對提議中的深海採礦計劃有關風險的新擔憂。

科學家發現，金屬小瘤之所以能夠產生氧氣，正是因為它們發揮類似電池的作用。

Sweetman教授解釋道: 「如果你把電池放入海水中，它就會開始發出嘶嘶聲」。 「那是因為電流實際上將海水分解成氧氣和氫氣（即氣泡）」。我們認為這些小瘤在自然狀態下就會發生這種情況。

他補充道: 「這就像手電筒中的電池」。 「你裝了一顆電池，它就不會亮。只要放入兩個，就有足夠的電壓來點亮手電筒。因此，當這些小瘤在海底相互接觸時，它們就會像多個電池一樣協同工作。

（待續）