Home Uncategorised Scientists map huge undersea fresh-water aquifer off US Northeast

Scientists map huge undersea fresh-water aquifer off US Northeast

Author

Date

Category

EARTH INSTITUTE AT COLUMBIA UNIVERSITY

In a new survey of the sub-seafloor off the U.S. Northeast coast, scientists have made a surprising discovery: a gigantic aquifer of relatively fresh water trapped in porous sediments lying below the salty ocean. It appears to be the largest such formation yet found in the world. The aquifer stretches from the shore at least from Massachusetts to New Jersey, extending more or less continuously out about 50 miles to the edge of the continental shelf. If found on the surface, it would create a lake covering some 15,000 square miles. The study suggests that such aquifers probably lie off many other coasts worldwide, and could provide desperately needed water for arid areas that are now in danger of running out.

The researchers employed innovative measurements of electromagnetic waves to map the water, which remained invisible to other technologies. “We knew there was fresh water down there in isolated places, but we did not know the extent or geometry,” said lead author Chloe Gustafson, a PhD. candidate at Columbia University’s Lamont-Doherty Earth Observatory. “It could turn out to be an important resource in other parts of the world.” The study appears this week in the journal Scientific Reports.

The first hints of the aquifer came in the 1970s, when companies drilled off the coastline for oil, but sometimes instead hit fresh water. Drill holes are just pinpricks in the seafloor, and scientists debated whether the water deposits were just isolated pockets or something bigger. Starting about 20 years ago, study coauthor Kerry Key, now a Lamont-Doherty geophysicist, helped oil companies develop techniques to use electromagnetic imaging of the sub-seafloor to look for oil. More recently, Key decided to see if some form of the technology could also be used also to find fresh-water deposits. In 2015, he and Rob L. Evans of Woods Hole Oceanographic Institution spent 10 days on the Lamont-Doherty research vessel Marcus G. Langseth making measurements off southern New Jersey and the Massachusetts island of Martha’s Vineyard, where scattered drill holes had hit fresh-water-rich sediments.

They dropped receivers to the seafloor to measure electromagnetic fields below, and the degree to which natural disruptions such as solar winds and lightning strikes resonated through them. An apparatus towed behind the ship also emitted artificial electromagnetic pulses and recorded the same type of reactions from the subseafloor. Both methods work in a simple way: salt water is a better conductor of electromagnetic waves than fresh water, so the freshwater stood out as a band of low conductance. Analyses indicated that the deposits are not scattered; they are more or less continuous, starting at the shoreline and extending far out within the shallow continental shelf — in some cases, as far as 75 miles. For the most part, they begin at around 600 feet below the ocean floor, and bottom out at about 1,200 feet.

The consistency of the data from both study areas allowed to the researchers to infer with a high degree of confidence that fresh water sediments continuously span not just New Jersey and much of Massachusetts, but the intervening coasts of Rhode Island, Connecticut and New York. They estimate that the region holds at least 670 cubic miles of fresh water. If future research shows the aquifer extends further north and south, it would rival the great Ogallala Aquifer, which supplies vital groundwater to eight Great Plains states, from South Dakota to Texas.

The water probably got under the seabed in one of two different ways, say the researchers. Some 15,000 to 20,000 years ago, toward the end of the last glacial age, much of the world’s water was locked up in mile-deep ice; in North America, it extended through what is now northern New Jersey, Long Island and the New England coast. Sea levels were much lower, exposing much of what is now the underwater U.S. continental shelf. When the ice melted, sediments formed huge river deltas on top of the shelf, and fresh water got trapped there in scattered pockets. Later, sea levels rose. Up to now, the trapping of such “fossil” water has been the common explanation for any fresh water found under the ocean.

But the researchers say the new findings indicate that the aquifer is also being fed by modern subterranean runoff from the land. As water from rainfall and water bodies percolates through onshore sediments, it is likely pumped seaward by the rising and falling pressure of tides, said Key. He likened this to a person pressing up and down on a sponge to suck in water from the sponge’s sides. Also, the aquifer is generally freshest near the shore, and saltier the farther out you go, suggesting that it mixes gradually with ocean water over time. Terrestrial fresh water usually contains less than 1 part per thousand salt, and this is about the value found undersea near land. By the time the aquifer reaches its outer edges, it rises to 15 parts per thousand. (Typical seawater is 35 parts per thousand.)

If water from the outer parts of the aquifer were to be withdrawn, it would have to be desalinated for most uses, but the cost would be much less than processing seawater, said Key. “We probably don’t need to do that in this region, but if we can show there are large aquifers in other regions, that might potentially represent a resource” in places like southern California, Australia, the Mideast or Saharan Africa, he said. His group hopes to expand its surveys.

With the COL banning ALL off shore exploration, what are the chances of us finding things like this?

7 COMMENTS

  1. We are very lucky here. 97% of the precipitation that falls on NZ ends up in the ocean. I have no idea why water-bottling is controversial. It should be Kiwis, not Chinese companies, exporting the stuff. It’s worth a fortune.

    Drilling for water on the sea bed, or desalination plants. I’d have no idea which would be cheaper.

    0

    0

  2. The taniwha would need to be placated via loads of cash first. Cash to be deposited to the nearest Maori entity. The taniwha will no doubt need royalties too.

    0

    0

      • I suspect the mere discovery of a new taniwha requires a massive injection of cash to the nearest Maori iwi irrespective of water use.

        0

        0

    • You say “Nature tends to fill empty spaces”.

      So Green Party MPs defy nature.
      empty vessels ‘n all.

      See: they are not pro-nature after all; just pro-totalitarianism.

      0

      0

Comments are closed.

Recent posts

No more migrants?

IS THE WORLD BECOMING LESS TOLERANT OF MIGRANTS? AP: Gallup poll says world becoming less tolerant of migrants Humbug.  Everything is wrong about this header. It’s not...

Tool shed extreme.

Body fat deep below the surface is a toxic risk, especially for your heart By Lea M D Delbridge, Professor of Physiology, University of Melbourne Amid...

Insider Trading?

Moderna Executives Caught Selling Millions In Stock As Covid Vaccine Trials Enter Phase 3 Baxter Dmitry: Moderna executives have been caught selling tens of millions of...

It Ain’t over till the voters vote

The 2020 New Zealand Election is Not a Foregone Conclusion By Keith Rankin:   The most recent TVNZ Colmar Brunton poll felt about right: Labour/Green on 54% and...

Recent comments

Editor on Have Your Say
Odakyu-sen on Have Your Say
Braybots nemesis on Have Your Say
waikatogirl on Have Your Say
Simpleton1 on Have Your Say
Simpleton1 on Have Your Say

The way we all feel about this useless government

Hamilton
scattered clouds
17.9 ° C
18.3 °
17.8 °
73 %
9.4kmh
28 %
Sun
17 °
Mon
14 °
Tue
13 °
Wed
12 °
Thu
14 °
NZD - New Zealand Dollar
USD
1.5300
EUR
1.7797
AUD
1.0753
CAD
1.1429
GBP
1.9500
JPY
0.0145
CNY
0.2242
INR
0.0208