Scientists map huge undersea fresh-water aquifer off US Northeast

Posted: June 23, 2019 by oldbrew in Electro-magnetism, exploration, research

Credit: thinglink.com


The world contains more fresh water than previously thought. It’s a question of looking in the right places, as this study explains.

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, reports Phys.org.

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 Ph.D. 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.

Full report here.

Comments
  1. Gamecock says:

    ‘could provide desperately needed water for arid areas that are now in danger of running out’

    Researchers declaring that what they do is very, very important.

    Envirowhackos tell us we are draining the world’s aquifers – OH NO! But now it’s okay to drain some more.

    ‘lead author Chloe Gustafson, a Ph.D. candidate’

    Stolen valor. She is a graduate student. She has not earned the right to use the term Ph.D. yet.

    Phys.org puffing it up; it’s what journalists do.

  2. michael hart says:

    Is it technically feasible to extract usable water from such aquifers in such “porous sediments”?
    I’m not sure what is meant. Is it chalk, or a stiff mud?

  3. Gamecock says:

    . . . and would it be cheaper to just desalinate sea water?

  4. pochas94 says:

    California should investigate. A state that runs into periodic water shortages needs to know. Cali is above a subduction zone, so chances may not be good.

  5. oldbrew says:

    Gamecock says: June 23, 2019 at 2:27 pm
    . . . and would it be cheaper to just desalinate sea water?
    – – –
    No…

    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.

  6. Ve2 says:

    New York will run out of electricity before they run out of water.

  7. Gamecock says:

    ‘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.’

    An assertion not in evidence.

    Pumping water from 30 miles out, and over 125 feet deep, would not be cheap.

    And I love this comment: “Removal of this water will come with predictable consequences, among them subsidence, salt water intrusion, erosion, and possibly clathrate methane release.”

    I think he’s against it.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s