Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Caustic soils at Hanford may lock up contaminants fast

30.03.2004


Soil particles lock up contaminants hundreds to thousands of times faster under the caustic conditions found beneath leaking toxic waste tanks at the Hanford Nuclear Reservation than under normal soil conditions, researchers report.



Understanding more about how contaminants such as radioactive cesium and strontium move through the soil under real-world conditions will help cleanup efforts at Hanford and other sites contaminated with nuclear waste. Previous research on the movement of soil contaminants had not replicated the extreme conditions found at the Hanford Site in Washington state.

"There’s a lot of interest in trying to determine the best approach to dealing with the massive subsurface waste at Hanford," said research team leader Jon Chorover, an associate professor of environmental chemistry at the University of Arizona in Tucson. "Our work helps predict the migration of this stuff. Understanding how these contaminants move in the soil can help with remediation."


Sunkyung Choi, a research associate at UA, will present the team’s finding at the 227th national meeting of the American Chemical Society.

Choi’s presentation, "Cesium and strontium uptake to clay minerals and their weathering products in a caustic waste," will be given at 4:15 p.m Pacific time on Monday, March 29, in Grand Ballroom D of the Anaheim Marriott, 700 West Convention Way, Anaheim, Calif.

Other members of the team include UA research specialist Mary Kay Amistadi and UA professor of materials science and engineering Supapan Seraphin. The research is funded by the U.S. Department of Energy.

At the Hanford Site, high-level nuclear waste from the manufacture of weapons is stored in 177 tanks buried in the soil. The waste contains toxic and highly radioactive elements, including plutonium, cesium 137 and strontium 90, mixed in with other materials that make the liquids in the tanks extremely caustic.

Weapons production began at the Hanford Site in 1944. Since then, 67 of the tanks have leaked, releasing highly radioactive liquid waste into the soil. Some of the contaminants have been found in the groundwater. Cost estimates for cleaning up the site run into the tens of billions of dollars.

Figuring out exactly how the wastes move through the soil is difficult because the tanks’ contents are complex mixtures of chemicals. But the contaminated soils and toxic wastes materials are too dangerous for the scientists to work with directly.

"If we were working with the concentrations of radioactivity that are out there, it would be lethal doses," Chorover said. "It would kill everyone in the lab."

He and his team are doing the next best thing. They have created non-radioactive chemical mixtures that match those in the Hanford tanks and are studying how those chemicals move through uncontaminated Hanford soil collected near the tanks.

In addition, to better understand how the different components of soil interact with the various chemicals, the team created some model soils to test with the Hanford-like chemical mixtures.

Even so, geochemical processes in soils occur over years, so the research, too, must be conducted over years, not days or weeks.

So to test how various liquid-and-soil mixtures interact over time, the researchers put the mixtures in small chemical-resistant plastic bottles and loaded the bottles onto mixers that look like mini-Ferris wheels.

The wheels, each of which holds more than 100 bottles, turn the bottles end-over-end. The wheels keep turning day, after day, after day. One of the experiments has been going on more than 2 years.

At set times, the researchers test the liquid and solid portions of bottles’ contents to see how chemicals from the liquid have reacted with the soil particles.

To the researchers’ surprise, over time the contaminants in the experimental set-ups were bound by newly formed clays in the soil, forming unusual minerals called zeolites and feldspathoids. The mineral particles, about a thousand times smaller than a grain of sand, don’t dissolve easily and therefore keep the contaminants trapped in the soil.

"We find the contaminants are remarkably slow to redissolve and appear to be more stable than initially thought," said Chorover. That stability may keep the contaminants from leaching deeper into the soil and the groundwater.

The team also found that the various clays from the soil and the various contaminants react differently with one another.

Although learning that contaminants get sequestered in solid particles seems like good news, Chorover is cautious.

"We really don’t know the lifetimes of these particles. We’ve shown it in the lab, but we don’t know what’s happening in the field," he said. "We do know contaminants are migrating through the soil in the field, so these laboratory results don’t explain all of what we see at Hanford."

The team’s next step is figuring out how stable the solids are and how long they last in the environment.

Jon Chorover | EurekAlert!
Further information:
http://www.arizona.edu/

More articles from Ecology, The Environment and Conservation:

nachricht International network connects experimental research in European waters
21.03.2017 | Leibniz-Institut für Gewässerökologie und Binnenfischerei (IGB)

nachricht World Water Day 2017: It doesn’t Always Have to Be Drinking Water – Using Wastewater as a Resource
17.03.2017 | ISOE - Institut für sozial-ökologische Forschung

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Giant Magnetic Fields in the Universe

Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.

The results will be published on March 22 in the journal „Astronomy & Astrophysics“.

Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...

Im Focus: Tracing down linear ubiquitination

Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.

Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...

Im Focus: Perovskite edges can be tuned for optoelectronic performance

Layered 2D material improves efficiency for solar cells and LEDs

In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...

Im Focus: Polymer-coated silicon nanosheets as alternative to graphene: A perfect team for nanoelectronics

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.

Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...

Im Focus: Researchers Imitate Molecular Crowding in Cells

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.

Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

International Land Use Symposium ILUS 2017: Call for Abstracts and Registration open

20.03.2017 | Event News

CONNECT 2017: International congress on connective tissue

14.03.2017 | Event News

ICTM Conference: Turbine Construction between Big Data and Additive Manufacturing

07.03.2017 | Event News

 
Latest News

Argon is not the 'dope' for metallic hydrogen

24.03.2017 | Materials Sciences

Astronomers find unexpected, dust-obscured star formation in distant galaxy

24.03.2017 | Physics and Astronomy

Gravitational wave kicks monster black hole out of galactic core

24.03.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>