Underground reservoir triple size of oceans found

[Greg Bernhardt]

The question is whether it's theoretically possible to tap this source for human use?

Scientists have found evidence of a huge underground reservoir containing up to three times as much water as on the entirety of the earth’s surface and theorized to be the source for all the world’s oceans.

The new evidence, published Friday in the journal Science, suggests that melting rocks, including those containing the water-rich mineral ringwoodite, may exist far deeper below the earth’s surface. The discovery suggests to researchers that most of the earth’s water seeped out from within, as opposed to arriving on ice-bearing comets, a theory many scientists have posited.

http://america.aljazeera.com/articles/2014/6/13/water-ringwooditeoceans.html

 

[OmCheeto]

The question is whether it's theoretically possible to tap this source for human use?

http://america.aljazeera.com/articles/2014/6/13/water-ringwooditeoceans.html

No need for comets? Interesting.
We had a discussion about how much water was locked in the Earth's crust awhile back. It was very interesting.
Wait! What's this?

[editorial nitpicking]

The findings back up another study from March, which focused on a diamond found 400 miles below the Earth's surface that was discovered to contain ringwoodite

I think they need a science editor to proof their articles. A quick google search indicates the deepest mine in the world is only 2.3 miles deep.
The diamond was formed 400 +/- x miles below the Earth's surface.
[/editorial nitpicking]​

Also, in another thread

It is estimated the Earth's oceans have lost about a quarter their water over the past ~ four billion years - http://sciencenordic.com/earth-has-lost-quarter-its-water. The current supply of water on Earth is estimated to be around 1.4 billion cubic kilometers.

That's quite a bit of water.

But my answer to your question is: "Just hang around volcanoes".

http://volcano.oregonstate.edu/what-are-some-good-things-volcanoes-do

Finally, on a very fundamental scale, volcanic gases are the source of all the water (and most of the atmosphere) that we have today.

Volcanic Gases and Their Effects

The most abundant gas typically released into the atmosphere from volcanic systems is water vapor (H2O), followed by carbon dioxide (CO2) and sulfur dioxide (SO2).

There's an interesting table on that second link.

Examples of volcanic gas compositions, in volume percent concentrations
(from Symonds et. al., 1994)

Volcano           Kilauea     Erta` Ale         Momotombo
Tectonic Style    Hot Spot    Divergent Plate   Convergent Plate
H20               37.1        77.2              97.1
C02               48.9        11.3               1.44
S02               11.8         8.34              0.50

97% of Momotombo's gas composition is H2O.

And can Kilauea's low H2O content imply a lower concentration in the mantle?

 

[Ophiolite]

Hmm.

Reservations:

1. It is misleading to say this is a reservoir of water. The ringwoodite absorbs, or more probably adsorbs, hydroxide ions.
2. Given the depths at which the ringwoodite is stable it seems equally probable that the water has been carried there by subduction, as that it has always been there.

What is needed are more recovered samples of ringwoodite on which we could determine oxygen isotope ratios for comparison with oceanic ratios.

As to the notion of tapping this for human use, the only practical method is Om Cheeto's suggestion: just hang around volcanoes. However, most of that is likely recycled.

 

[D H]

Related: Nature News article "Tiny diamond impurity reveals water riches of deep Earth". This article discusses the paper http://www.nature.com/nature/journal/v507/n7491/full/nature13080.html.

Calling this water is perhaps misleading. It is not free water. It is instead hydroxide ions absorbed by ringwoodite, a high pressure polymorph of olivine. Whether this water came from the oceans or is a source of the oceans, nobody knows.

 

[OmCheeto]

...
Whether this water came from the oceans or is a source of the oceans, nobody knows.

My hypothesis, based on the snippet from Greg's article:

The discovery suggests to researchers that most of the earth’s water seeped out from within, as opposed to arriving on ice-bearing comets, a theory many scientists have posited.

is that either explanation is valid. Wasn't the Earth formed at the same time as the rest of the solar system? Weren't all the planets vacuuming up comets and debris left and right back then? It makes sense to me that once the planet coalesced, over time, all of the elements and molecules would naturally stratify. So there's really no good reason, IMHO, to believe it wasn't here all along.

But it looks like the people who have the tidbit of Ringwoodite are thinking of putting it to the test:

Where it all began

There are two theories as to where the mantle's water came from. One is that it was ocean water that was carried deep underground when sea-floor rocks were subducted by plate tectonics. The other is that deeper layers of the Earth still contain water that was part of the materials that formed the Earth.

If the water has been there since Earth formed, its ratio of deuterium to normal hydrogen could be different from that found in sea water today—and closer to the composition of the Earth’s primordial water. If so, that ratio could provide clues as to whether the water came from asteroids or from comets, says Humberto Campins, an asteroid researcher at the University of Central Florida in Orlando.

Pearson sees a value to checking the isotope ratio, but so far his group has been unwilling to do such destructive tests on the only known piece of mantle ringwoodite. “We have to think really carefully on what we do next on this sample because it’s very small: 40 micrometres,” he says. “That means you can only think of doing one or two additional analyses.”

I find it fascinating that such a tiny fragment, can answer a centuries old question.

Yay Science!