MRI-type tool scans for water pollution on LI

The same technology that helps doctors analyze knee pain is being used by scientists on Long Island to study groundwater and predict where it may become polluted.

The nuclear magnetic resonance tool, like a medical MRI, uses high-powered magnets to move hydrogen molecules around and measure their reaction. U.S. Geological Survey scientists are using the technology to evaluate water flow and capacity in aquifers, the underground supplies that provide water for the 2.8 million residents of Nassau and Suffolk counties, for the first time.

Studying water sources at the molecular level could help researchers, water districts and environmentalists pinpoint the best sites and depths for wells, officials said.

"It saves time and it saves money," said Carrie Meek Gallagher, chief sustainability officer for the Suffolk County Water Authority, the county's largest water provider.

USGS scientists last week used the device on Long Island for the first time, testing it in a small field off County Road 48 in Southold near a Suffolk County Water Authority well site.

"What we're going to be able to tell is how much of the water is stuck in the clay and how much of it is actually moving," said Frederick Stumm, a research hydrologist at the USGS Water Science Center in Coram.

The magnetic resonance tool had only been used in the oil industry. But technological advances have produced a much smaller version that can be used in field studies, such as in water wells, said Carole Johnson, a USGS hydrologist based in Storrs, Conn.

Water in the Upper Glacial aquifer in the area around the Southold well has been contaminated by a road salt. Using the magnetic resonance tool to study how water moves in the shallow aquifer should help hydrogeologists determine which portions of it may be more susceptible to contamination and how wells may be impacted.

"The bottom line is the aquifer doesn't change, but the water does," Johnson said.

To get data to study, the USGS scientists dug a well 100 feet deep and inserted a nearly 2-inch-wide PVC pipe. The magnetic resonance tool, a cylinder 1.75 inches thick and about 6.5 inches long, was lowered down the pipe.

The device stopped about every 3 feet so its magnet could attract hydrogen molecules in water and send out a radio frequency pulse, making the molecules react. A computer recorded movement and sound.

The Upper Glacial aquifer is a mix of sand, pebbles, rocks and boulders. Molecules that move quickly are in areas where water flows freely. Those that are slower or stationary indicate clogged water, Stumm said.

What that means varies based on conditions, officials said. Water that is stuck is good news when it comes to contamination because toxins would not spread, but it also means that a particular area would be a bad place for a well, Stumm said.

"You're getting a picture of hydrology," said Elliot Grunewald, chief geophysicist at Vista Clara Inc., the Washington state company that developed the tool. "It's just an incredibly rich data set you get out of these measurements."

The device is called a nuclear magnet because it works at the molecular level, "exciting the nucleus" of molecules, said David L. Campbell, an adjunct professor in geophysics at University of Iowa. "It is definitely not putting a nuclear source down a hole," he said.