Featured Research

from universities, journals, and other organizations

"Green Rust" Shows Promise In Eliminating Selenium Soil Contamination

Date:
January 28, 1998
Source:
Lawrence Berkeley National Laboratory
Summary:
A surprising alternative to microorganisms for immobilizing selenium contamination in soil and sediment has been identified by researchers at the U.S. Department of Energy's Lawrence Berkeley National Laboratory. Green rust, a harmless natural iron oxide, was shown to chemically react with toxic selenium, converting it to a safer elemental form.

BERKELEY, CA. -- A surprising alternative to microorganisms for immobilizing selenium contamination in soil and sediment has been identified by researchers at the U.S. Department of Energy's Lawrence Berkeley National Laboratory. Green rust, a harmless natural iron oxide, was shown to chemically react with toxic selenium, converting it to a safer elemental form.

Selenium is a trace mineral that can be highly toxic or carcinogenic to humans and wildlife. The poisoning deaths of wild birds at the Kesterson Reservoir in the San Joaquin Valley in the early 1980s have been attributed to selenium in drainage from irrigation water. The incident was a graphic demonstration of how agricultural development can result in the accumulation of abnormally high and potentially lethal concentrations of selenium and other trace contaminants in soils and sediments.

Selenium's fate in contaminated soils has long been linked to the decomposition of plant material and other microbial activity, which was thought to be the primary means by which soluble, chemically active forms of selenium could be reduced to an elemental state. Elemental selenium is insoluble, which means it is less of a threat to move up through the soil into the food chain, or down through the soil into the groundwater.

Contrary to this past belief, however, a laboratory study led by Satish Myneni of Berkeley Lab's Earth Sciences Division, has revealed that green rust has the same effect as microorganisms on soluble forms of selenium.

"We have shown that the selenium transformation reaction in sediments and soils reduction can take place without the presence of the bacteria, via a different mechanism," says Myneni.

Joining him in this study were Tetsu Tokunaga, also with Berkeley Lab's Earth Sciences Division, and Gordon Brown, Jr., at the Stanford Synchrotron Radiation Laboratory. Their results were reported in a recent issue of the journal SCIENCE (11/7/97).

Although Myneni and his colleagues are not proposing any remediation strategy for selenium contaminated sites based on green rust, future cleanups and environmental management efforts depend upon a thorough understanding of selenium's basic chemistry and geochemical cycling. Furthermore, the green rust transformation reactions they have identified in selenium should also apply to other trace contaminants as well, such as chromium, and chlorinated hydrocarbons.

The researchers analyzed their reactions using various x-ray beam techniques, including x-ray absorption near edge structure (XANES), and extended x-ray absorption fine structure spectroscopy (EXAFS). A key to their findings was that the selenium transformation reactions take place under conditions of oxygen-depletion such as in the sediment beneath ponded water. These are the same conditions under which green rust is formed.

"Other researchers have shown that elemental iron and ferrous oxides can reduce soluble selenium to a less active state, but, unfortunately, these two forms of iron oxides do not occur in nature," says Myneni. "On the other hand, recent thermodynamic and kinetics studies show that green rust may be an important mineral in anoxic sediments."

Myneni and his colleagues are now in the process of analyzing samples of soils and sediments collected from selenium-contaminated sites for the presence of green rust. For this work, they will use the x-ray microscopy beamline at Berkeley Lab's Advanced Light Source.

The Berkeley Lab is a U.S. Department of Energy national laboratory located in Berkeley, California. It conducts unclassified scientific research and is managed by the University of California.


Story Source:

The above story is based on materials provided by Lawrence Berkeley National Laboratory. Note: Materials may be edited for content and length.


Cite This Page:

Lawrence Berkeley National Laboratory. ""Green Rust" Shows Promise In Eliminating Selenium Soil Contamination." ScienceDaily. ScienceDaily, 28 January 1998. <www.sciencedaily.com/releases/1998/01/980128073645.htm>.
Lawrence Berkeley National Laboratory. (1998, January 28). "Green Rust" Shows Promise In Eliminating Selenium Soil Contamination. ScienceDaily. Retrieved July 22, 2014 from www.sciencedaily.com/releases/1998/01/980128073645.htm
Lawrence Berkeley National Laboratory. ""Green Rust" Shows Promise In Eliminating Selenium Soil Contamination." ScienceDaily. www.sciencedaily.com/releases/1998/01/980128073645.htm (accessed July 22, 2014).

Share This




More Plants & Animals News

Tuesday, July 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Michigan Plant's Goal: Flower and Die

Michigan Plant's Goal: Flower and Die

AP (July 22, 2014) An 80-year-old agave plant, which is blooming for the first and only time at a University of Michigan conservatory, will die when it's done (July 22) Video provided by AP
Powered by NewsLook.com
San Diego Zoo Welcomes New, Rare Rhino Calf

San Diego Zoo Welcomes New, Rare Rhino Calf

Reuters - US Online Video (July 21, 2014) An endangered black rhino baby is the newest resident at the San Diego Zoo. Sasha Salama reports. Video provided by Reuters
Powered by NewsLook.com
Shark Sightings a Big Catch for Cape Tourism

Shark Sightings a Big Catch for Cape Tourism

AP (July 21, 2014) A rise in shark sightings along the shores of Chatham, Massachusetts is driving a surge of eager vacationers to the beach town looking to catch a glimpse of a great white. (July 21) Video provided by AP
Powered by NewsLook.com
$23.6 Billion Awarded To Widow In Smoking Lawsuit

$23.6 Billion Awarded To Widow In Smoking Lawsuit

Newsy (July 20, 2014) Cynthia Robinson claims R.J. Reynolds Tobacco Company hid the health and addiction risks of its products, leading to the death of her husband in 1996. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins