Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Munching microbes could cleanse arsenic-contaminated groundwater

27.10.2004


Microbial processes ultimately determine whether arsenic builds to dangerous levels in groundwater, say researchers at the University of Illinois at Urbana-Champaign. Remediation may be as simple as stimulating certain microbes to grow.



Arsenic contamination is a serious threat to human health. In the Ganges Delta of Bangladesh, for example, chronic exposure to arsenic has been linked to serious medical conditions, including hypertension, cardiovascular disease and a variety of cancers. "The threat extends to Central Illinois, where there are very high levels of arsenic contamination in a number of wells," said Craig Bethke, a professor of geology at Illinois and corresponding author of a paper to appear in the November issue of the journal Geology. "We also discovered important links between the amount of organic material dissolved in the groundwater and the concentrations of sulfate and arsenic."

The researchers analyzed water from 21 wells at various depths in the Mahomet aquifer, a regional water supply for Central Illinois. "The Mahomet aquifer was produced by a glacier, which pulverized and homogenized the sediments," Bethke said. "As a result, arsenic sources that leach into the groundwater are pretty uniformly distributed." Surprisingly, however, arsenic concentration varied strongly from well to well, Bethke said. "Concentrations may reach hundreds of micrograms per liter in one well – which is enough to make people very sick – but fall below detection limits in a nearby well."


The concentration of arsenic varied inversely with the concentration of sulfate, the researchers found. Methane concentration also varied with the sulfate content. "We believe this reflects the distribution of microbial populations in the aquifer system," said graduate student Matthew Kirk. "Our analyses suggest the aquifer is divided into zones of mixed microbial activity, some dominated by sulfate-reducing bacteria, others by methanogens." Sulfate-reducing bacteria will consume sulfate and reduce it into sulfide. The sulfide then reacts to precipitate arsenic, leaving little in solution.

If the sulfate-reducing bacteria run out of sulfate, methanogenic bacteria take over as the dominant metabolic force, Kirk said. Because methanogenic bacteria don’t produce sulfide, there is no precipitation pathway for the arsenic, which then accumulates to high levels in the groundwater. "In the Mahomet aquifer, the balance between the amount of organic material and the amount of sulfate that leaches into the groundwater appears to control whether the water becomes contaminated," Kirk said. "Where the supply of sulfate is high relative to organic matter, sulfate remains available and sulfate-reducing bacteria keep arsenic levels low. But, where the supply of organic matter is high relative to sulfate, the sulfate has been depleted, and arsenic may accumulate."

What does this mean to people living in Illinois?

"The majority of wells in Central Illinois belong to individual homes and farms," Bethke said. "Lacking effective water treatment and testing, private wells are more at risk of arsenic poisoning."

There is good news, however. The researchers’ findings suggest that groundwater contaminated with arsenic might be easily identified and remediated.

"Unlike detecting the presence of arsenic – which generally requires a sensitive laboratory analysis – testing for sulfate is simple and straightforward," Bethke said. "If all waters containing sulfate are safe, as in our dataset, then measuring sulfate level would be an easy but reliable field test to identify safe drinking water from unsafe."

Adding sulfate to naturally contaminated groundwater might be a simple but effective method to sequester the arsenic, Kirk said. "The bacteria are already present, so all you have to do is stimulate them." Sulfate salts, he said, are inexpensive, readily soluble and easily obtained.

In addition to Bethke and Kirk, the team included UI geology professor Bruce Fouke, research scientist Robert Sanford, graduate students Jungho Park and Gusheng Jin, and Illinois State Water Survey project scientist Thomas Holm. The U.S. Department of Energy funded the work.

James E. Kloeppel | EurekAlert!
Further information:
http://www.uiuc.edu

More articles from Ecology, The Environment and Conservation:

nachricht Dispersal of Fish Eggs by Water Birds – Just a Myth?
19.02.2018 | Universität Basel

nachricht Removing fossil fuel subsidies will not reduce CO2 emissions as much as hoped
08.02.2018 | International Institute for Applied Systems Analysis (IIASA)

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: In best circles: First integrated circuit from self-assembled polymer

For the first time, a team of researchers at the Max-Planck Institute (MPI) for Polymer Research in Mainz, Germany, has succeeded in making an integrated circuit (IC) from just a monolayer of a semiconducting polymer via a bottom-up, self-assembly approach.

In the self-assembly process, the semiconducting polymer arranges itself into an ordered monolayer in a transistor. The transistors are binary switches used...

Im Focus: Demonstration of a single molecule piezoelectric effect

Breakthrough provides a new concept of the design of molecular motors, sensors and electricity generators at nanoscale

Researchers from the Institute of Organic Chemistry and Biochemistry of the CAS (IOCB Prague), Institute of Physics of the CAS (IP CAS) and Palacký University...

Im Focus: Hybrid optics bring color imaging using ultrathin metalenses into focus

For photographers and scientists, lenses are lifesavers. They reflect and refract light, making possible the imaging systems that drive discovery through the microscope and preserve history through cameras.

But today's glass-based lenses are bulky and resist miniaturization. Next-generation technologies, such as ultrathin cameras or tiny microscopes, require...

Im Focus: Stem cell divisions in the adult brain seen for the first time

Scientists from the University of Zurich have succeeded for the first time in tracking individual stem cells and their neuronal progeny over months within the intact adult brain. This study sheds light on how new neurons are produced throughout life.

The generation of new nerve cells was once thought to taper off at the end of embryonic development. However, recent research has shown that the adult brain...

Im Focus: Interference as a new method for cooling quantum devices

Theoretical physicists propose to use negative interference to control heat flow in quantum devices. Study published in Physical Review Letters

Quantum computer parts are sensitive and need to be cooled to very low temperatures. Their tiny size makes them particularly susceptible to a temperature...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

2nd International Conference on High Temperature Shape Memory Alloys (HTSMAs)

15.02.2018 | Event News

Aachen DC Grid Summit 2018

13.02.2018 | Event News

How Global Climate Policy Can Learn from the Energy Transition

12.02.2018 | Event News

 
Latest News

Researchers invent tiny, light-powered wires to modulate brain's electrical signals

21.02.2018 | Life Sciences

The “Holy Grail” of peptide chemistry: Making peptide active agents available orally

21.02.2018 | Life Sciences

Atomic structure of ultrasound material not what anyone expected

21.02.2018 | Materials Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>