ATTA — This diagram shows the major components of the Atom-Trap Trace Analysis device, which allows researchers to count individual atoms of krypton isotopes in a sample.

ATTA reveals secrets of vital Mideast aquifer

By Dave Jacqué

Using an ultra-sensitive detector developed at Argonne, researchers have determined, for the first time, the age and direction of movement of water in the largest underground aquifer in the Middle East.

Researchers from Argonne, the University of Illinois at Chicago (UIC), the University of Bern, Switzerland, and the Egyptian Geological Survey and Mining Authority gathered samples of a rare gas, krypton-81, from the Nubian aquifer, a huge reservoir of fresh water below the Egyptian desert. The samples' ages were determined using Atom Trap Trace Analysis (ATTA) developed by an Argonne team, led by Argonne physicist Zheng-Tian Lu, with team members Kevin Bailey, Xu Du, Peter Mueller, Thomas O'Connor (all PHY) and Linda Young (CHM).

Krypton-81 is produced by cosmic rays interacting with the earth's atmosphere. Its isotopic abundance is roughly the same all over the world, it doesn't combine with other materials, and it has no underground sources. Its half-life of 230,000 years makes it nearly ideal for dating water between 50,000 and about two million years old.

Other isotopes used for dating, like chlorine-36, have sources underground from radioactive decay or residual seawater from when sediments were deposited. Since chlorine is a major constituent of salt, chlorine-36 can't be used to date seawater.

"Krypton-81 is about as ideal for dating purposes as you can find in nature," said UIC professor Neil Sturchio, a former member of Argonne's Environmental Research Division. "The only problem has been that it's been very difficult to measure until the ATTA method came along."

Krypton-81 is rare and not very soluble in water, so the amount that mixes into surface water is small -- on average, just 2,000 atoms per liter of surface water. To get enough for an accurate measurement required stripping the krypton gas from up to three tons of groundwater.

Lu joined Sturchio and other researchers on an expedition to Egypt in 2002 to gather the gas samples. Lu's previous discussions with Sturchio led to the idea of dating groundwater with ATTA.

The expedition involved cutting through lots of red tape, including getting "desert permits" granted by Egyptian military. "In Egypt, they consider water resources sensitive information," Sturchio said. "It's strategic."

Once in the desert, the team took samples from wells at six locations. "It took some quick thinking to adapt our sampling equipment to the configuration of the local wells," Sturchio said. "In most cases, it's just water gushing out of a big pipe. We improvised and got good samples."

To collect the gas, they ran a flexible hose into the well outlet, usually just a large pipe spilling water into an irrigation system or common well. The hose ensured that the water sample was uncontaminated by krypton gas in the atmosphere.

The water sample was piped to a chamber under a partial vacuum. Dissolved gasses released from the water were pumped into airtight steel cylinders. It took up to three tons of water passing through the system to create a sufficient sample, a process that took several hours. The team was careful to return all the sampled water so it could be used by area residents.

"The hard part was making sure things worked in the field," Lu said. "If one of the pumps stopped, or if the generator died, we were done. In the lab, it would be easy to fix them. But we were out in the desert."

Although the team suffered no major setbacks, by the end of the week everyone was exhausted, Lu said.

The collected gases were shipped to the University of Bern, where they were separated, purified and concentrated. The samples were then sent to Argonne for measurement with ATTA.

Counting atoms

ATTA was first developed in 1999. Since then, refinements in equipment and procedures have improved the method's efficiency more than 1,000 times.

In the table-top device, a trickle of krypton gas is injected through a radio-frequency discharge, which excites the atoms. The atoms are slowed to just 20 meters per second with a combination of lasers and magnetic fields. Another set of lasers halts the atoms and holds them in place. While in the trap, a krypton atom scatters millions of photons per second from the laser beams. A photon detector records the arrival and departure of individual atoms.

Recirculating the gas sample is one of the many improvements to ATTA. "Noble gases like krypton don't stick to the walls. So you can take the gas, feed it back to the source and measure it again, increasing the efficiency," Lu said.

The samples ranged in age from 200,000 to 1,000,000 years and suggest a flow pattern north and east toward the Mediterranean Sea at about two meters (six feet) per year, "about the same rate as grass grows," Sturchio said.

The water's source seems to be the Uweinat Uplift, near the Egypt-Sudan border, where the Nubian Aquifer sandstone is exposed or buried beneath a relatively shallow layer of sand.

Next steps

Lu is already making plans for ATTA III, which may be able to improve efficiency 100 times over the current model, ATTA II.

"Then we can get the amount of water needed to 100 kilograms, maybe less, something two people can carry," Lu said. "In principle, it's possible to get 100 percent efficiency, but I won't make any promises to my geologist friends."

There are a multitude of potential geological targets for the ATTA method, Sturchio said. For example, much of the groundwater circulation beneath Yellowstone National Park -- the power source for the Old Faithful geyser -- is unknown. Groundwater in certain parts of Kansas and Oklahoma apparently comes from the Rocky Mountains; nobody really knows how long it takes or what path it takes to get there. A thousand feet below the cornfields of Illinois, the groundwater is salty, and nobody knows if it's been there for one million years or 100 million.

"This is a pattern that has repeated many times in geology," Sturchio said. "Physicists develop research tools like the mass spectrometer, electron microscope, measurements of the half-lives of isotopes. Geologists can take these tools and apply the knowledge to understanding how the earth works."

For more information on this research:

"One Million Year Old Groundwater In The Sahara Revealed By Krypton-81 And Chlorine-36" Geophys. Res. Lett., Vol. 31, No. 5, 12. March 2004

American Geophysical Union press release: www.agu.org/sci_soc/prrl/prrl0411.html

For worldwide news coverage of this research, search "krypton 81 sahara" on Google.com.

Young women explore scientific and technical careers

More than 300 students from 46 schools throughout the Chicago area participated in the 17th annual Science Careers in Search of Women conference, held at the laboratory March 12.

"The conference is designed to expose students to a variety of careers in science and engineering and real-life women in those professions. I hope we inspire many of the students to pursue technical careers," said Argonne's Kirsten Laurin-Kovitz (TD), chair of the conference. "If we broaden the outlook of even one girl it will be worth it."

The conference's keynote address was given by Denise Casalino, Commissioner of the Department of Planning and Development, City of Chicago. Casalino is a civil engineer who has directed many major engineering projects including the $200 million Wacker Drive reconstruction project in Chicago.

Students participated in panel discussions with speakers from a variety of scientific and engineering disciplines and had the opportunity for more informal conversation with women scientists during lunch. The students also went on several different laboratory tours including biology, chemistry, physics, computer science and engineering and visited career booth exhibits.

The conference is sponsored by Argonne's Office of the Director and Division of Educational Programs and the U.S. Department of Energy's Office of Science.

Argonne honors two innovative science teachers

Katherine Kaufman, an earth science teacher at South Middle School in Arlington Heights, and Jay Walgren, a physical science teacher at Warren Township High School in Gurnee, were winners of Argonne's Ellis P. Steinberg Award for Pre-College Science Teaching.

The Steinberg Award is given annually to Illinois science teachers who have shown excellence and innovation in teaching science. Kaufman and Walgren each received $500 and a plaque.

Both teachers have an impressive reputation for making students passionate about science. Kaufman is known for engaging her classes with demonstrations using graham crackers to illustrate the dynamics of plate tectonics. Walgren embodies a similar spirit of creativity for his students by building hoverboards -- vehicles that use air flow to levitate and move around in a near-frictionless manner.

This enthusiastic spirit continues far beyond the walls of the classroom. Kaufman and Walgren also lead a wide array of extracurricular activities for students, ranging from Science Olympiad competitions to robot-building sessions. Both teachers have inspired numerous teams of students to compete and succeed at a number of regional, state and national science competitions.

The Steinberg Award honors the commitment to excellence in science education as demonstrated by the late Ellis P. Steinberg, who built an illustrious career in nuclear chemistry. He worked on the research program that achieved the first controlled sustained nuclear chain reaction, supplied data on fission reactions for the Manhattan Project and led a research group at Argonne's Zero Gradient Synchrotron.

Steinberg was director of Argonne's Chemistry Division from 1982 to 1988. After retiring, he remained active in the Division of Educational Programs (DEP), working to improve the quality of science education and organizing workshops for students and teachers.

Students, parents and community members may submit nominations for the Steinberg Award. Selection criteria include leadership in the science education community, participation in developmental programs that enhance scientific expertise and teaching skills, and encouraging students to participate in extracurricular activities related to science.

The Steinberg Award is run by DEP and the Argonne chapter of Sigma Xi. Funds for the award are provided by family, friends and former colleagues of Steinberg.

Club plans April Fools celebration

The Argonne Club will host an April Fools party Thursday, April 1, in Argonne-East's Building 617 Lower Level from 4:30 - 8 p.m.

Adult beverages will be available, and there will be a raffle.

All visitors must be badged by the Argonne Information Center prior to 4 p.m. For more information, contact the Argonne Club at argonneclub@anl.gov or visit the Argonne Club Web site.

Tickets for Leipzig Quartet go on sale

Tickets go on sale Monday, March 29, for a performance by the Leipzig String Quartet at Argonne-East.

Tickets are $25 and will be sold in the Building 213 Cafeteria between noon and 1 p.m.

The concert will begin at 3 p.m. Sunday, April 4, in the Building 402 Conference Center. The quartet will perform compositions by Mendelssohn, Beethoven and Brahms.

The concert is sponsored by Arts at Argonne, the laboratory's fine arts program.

Flex spending account claims deadline near

Flexible spending account claims for 2003 must be postmarked by Wednesday, March 31.

For more information, contact Human Resources-Employee Benefits at ext. 2-2989 (Argonne East) or ext. 3-7361 (Argonne West).

Guest House `Taste of Two Islands' rescheduled

The "Taste of Two Islands" reception and dinner at the Argonne Guest House has been rescheduled due to a conflict with another event. The dinner will be held Friday, April 16.

A reception will begin at 5:30 p.m., followed by dinner at 6:30.

The meal will comprise five courses, each served with two wines. Entrees include grilled quail and seared beef tenderloin.

The event costs $68 per person not including tax and gratuity; group rates are available. Dinner attendees can purchase wine by the bottle or the case.

For more information or to make a reservation, contact Kathy at (630) 739-6000.

Zeiss 'scopes to be shown in mobile lab

The "Mat Mobile," an 18-wheel microscopy laboratory from Carl Zeiss, Inc., will visit Argonne-East Wednesday, May 19.

The Mat Mobile will exhibit materials microscopes in the Building 212 parking lot, just south of the Building 213 Cafeteria, from 9 a.m. to 4 p.m.

Zeiss is touring the United States to showcase and demonstrate its newest optics and contrasting techniques for research and materials analysis. Equipment on display will include stereo and laser scanning confocal microscopes.

Severe weather training offered

Employees interested in astrophysics research at Argonne and the University of Chicago are invited to a new monthly series of half-hour discussions and presentations.

Argonne Astrophysics Luncheons will be held on the first Thursday of each month at noon in Argonne-East's Building 213 Cafeteria. The first meeting will be April 1.

The luncheons are a response to an increased interest in astrophysics and cosmochemistry at Argonne over the last few years among people working in several different divisions.

Anyone with suggestions for future luncheons can contact one of the organizers: Ken Nollett (PHY) at ext. 2-8264 or nollett@anl.gov, Michael Pellin (MSD) at ext. 2-3510 or pellin@anl.gov, Ernst Rehm (PHY) at ext. 2-4073 or rehm@anl.gov, or Jim Truran (University of Chicago and PHY) at (773) 702-9584 or truran@nova.uchicago.edu.

Questions about Social Security to be answered

A representative of the Social Security Administration's Joliet office will visit Argonne-East's Human Resources office Wednesday, April 21, from 8 a.m. to noon.

To schedule a meeting, call ext. 2-2989.

Astrophysics on menu at monthly luncheons

Employees interested in learning to observe and report severe weather are welcome to attend a training session hosted by the Argonne Amateur Radio Club Tuesday, April 6.

Meteorologist Jim Allsopp of the National Weather Service Forecast Office in Romeoville will present the program, which will start at 7 p.m. in Argonne-East's Building 951 (the Recreation Center in Argonne Park).

The session will be open to the public and will qualify as a training meeting for those in the trained weather spotter program. The session is free, and no registration is needed.

Champs to demonstrate Rube device

The winner of Argonne's Rube Goldberg machine contest for Chicago-area high schools will receive their first-place trophy and demonstrate their machine at noon Wednesday, March 31, in Argonne-East's Building 213 Cafeteria.

Morgan Park Academy defeated 10 other Chicago-area high schools Feb. 13 at Navy Pier by building the best machine to select, mark and cast an election ballot in 20 or more steps.

Morgan Park will compete for the 2004 Illinois state championship against five other Illinois high schools Saturday, April 17, at the Chicago Children's Museum on Navy Pier.

Video of the winning machine is online.

Valid passports required for non-immigrants

All non-immigrants residing in the United States are required to maintain a valid foreign passport at all times. Passports should be renewed prior to the expiration date. Renewals must be requested from the consulate or embassy. Also, it is recommended that non-immigrants carry their passports and other relevant visa documents on their persons at all times. For clarification or additional information, contact Nancy Griparis at ext. 2-2967 or ngriparis@anl.gov.

Golfers wanted

The Argonne Reactor Golf League is looking for new members for the 2004 season. The league plays Thursday evenings at the Gleneagles Country Club in Lemont.

The Reactor Golf League is one of Argonne's original golf leagues, and 2004 marks its 46th season. Play begins April 22 and lasts until Sept. 16.

All employees, retirees and friends are welcome to join. For more information, contact Judy Gross (NE) at ext. 2-6347.