Mike MalaskaJul 22, 2024

Weird oxygen production from metal nodules at the bottom of the ocean.

Link to summary article: https://www.nature.com/articles/d41586-024-02393-7#:~:text=The%20phenomenon%20was%20discovered%20in,published%20in%20Nature%20Geoscience1.

The authors found oxygen getting produced at the bottom of the ocean. They thought it was from instrument or experimental hiccups...but no, it's real.

So what's going on? And what are the implications for #astrobiology in the deep oceans of the #OceanWorlds ?

[Thread]

Mystery oxygen source discovered on the sea floor — bewildering scientists

A chemical reaction could be producing oxygen by splitting water molecules, but its source of energy remains unknown.

Show threadMike MalaskaJul 22, 2024

The authors were sending a "lander" down into the sunless depths of the ocean, over 4 km down.

There they used chambers to measure gases and they noticed O2 was being produced. Rapid at first, then it tapered off.

There's no sunlight, so plants or algae weren't doing it. So what was making the O2?

They carefully checked everything. Not instrument or equipment artifact. It was real. They determined that radiolysis from radioactive atoms splitting water couldn't account for all of it.

Show threadMike MalaskaJul 22, 2024

They found polymetal nodules in that location. They probed the nodules with electrodes and found the electric potential where they looked was just below what was needed to split water.

But if some of those metal surfaces were connected in series, it could create a "geo-battery" (their term) that would be enough to split water.

Their idea is that the landers thruster blew the sediment off the nodules and created a fresh active surface that split water. When depleted, O2 production slowed down.

Show threadMike Malaska

So what are the implications?

For life on Earth, it means you've got these geologically produced metal nodules that can make oxygen at the bottom of the ocean....at least when activated. That O2 could be useful for respiration used by microbes. O2 is a great "fuel". Those nodules effectively create, at least temporarily, a local O2-rich environment.

(So it would be really uncool to mine them and screw up that special environment.)

Jul 22, 2024 at 11:05pmWeb
Show threadMike MalaskaJul 22, 2024

For #astrobiology and life on other worlds deep down, it gives you a way to make oxygen (a wonderful fuel for metabolism). At least as long as you have those metal nodules.

(Sorry, y'all, Titan prolly won't have this. Titan's core is hydrous silica, not porous due to high pressure).

But...maybe some of the active Galileans (Europa) or smaller icy worlds that are porous (Enceladus, Miranda).

However, the O2 production is a one-shot deal, once redox is quenched it doesn't regenerate.

Show threadMike MalaskaJul 22, 2024

And here is the link to the full paper: https://www.nature.com/articles/s41561-024-01480-8

Enjoy!

[End thread]

Evidence of dark oxygen production at the abyssal seafloor - Nature Geoscience

Oxygen is generated abiotically at the abyssal seafloor in the presence of polymetallic nodules, potentially by seawater electrolysis, according to in situ chamber and ex situ incubation experiments.

Nature