Navigation Links
Waterborne carbon increases threat of environmental mercury
Date:12/10/2007

MADISON - Mercury is a potent neurotoxin and a worrisome environmental contaminant, but the severity of its threat appears to depend on what else is in the water.

Researchers at the University of Wisconsin-Madison have found that the presence of dissolved organic material increases the biological risk of aqueous mercury and may even serve as an environmental mercury source.

Mercury is present throughout the environment in small quantities in rocks and in watery environments, including lakes, wetlands and oceans. It accumulates in fish living in mercury-contaminated waters, posing a health risk to animals and humans who eat the tainted fish.

The greatest threat comes from a form called methylmercury, which is more easily taken up by living tissues. The methylation process, therefore, is key to understanding the potential danger posed by environmental mercury, says UW-Madison geomicrobiologist John Moreau.

He presented his research findings at the American Geophysical Union meeting in San Francisco today (Dec. 10).

Environmental mercury is predominantly methylated by naturally occurring bacteria known as sulfate-reducing bacteria. These bacteria - Moreau calls them "little methylmercury factories" - absorb inorganic mercury from the water, methylate it and spit methylmercury back out into the environment.

"The bacteria take mercury from a form that is less toxic to humans and turn it into a form that is much more toxic," Moreau says. "[Methylation] increases mercury's toxicity by essentially putting it on a fast train into your tissue - it increases its mobility."

Many previous studies have focused on the chemical interactions between mercury and sulfur, which is known to bind to inorganic mercury and may regulate how well the bacteria can absorb it. However, scientists do not understand the factors that control the methylation process itself.

"Those studies have related methylation potential to geochemical variables," Moreau says. "We would like to take a bacterium that we know methylates mercury very efficiently and let it tell us what it can methylate and what it can't, under given conditions."

Moreau and colleagues at the U.S. Geological Survey, UW-Madison, the University of Colorado and Chapman University chose to look at the role of dissolved organic carbon (DOC), a richly colored brew created as plants and other organic materials decay into a soup of proteins, acids and other compounds. DOC can tint wetlands and streams shades of yellow to dark brown.

DOC has noticeable effects on bacterial mercury processing. "They seem to methylate mercury better with DOC present," says Moreau.

In the current studies, the scientists looked at the effects of DOC samples collected from two different organic-rich environments, a section of the Suwannee River and Florida's Everglades.

"We found that different DOCs have different positive effects on methylation - they both seem to promote mercury methylation, but to different degrees," Moreau explains.

Because DOC is virtually ubiquitous in aqueous environments, its effect on mercury processing may be an important factor in determining mercury bioavailability.

Moreau and his colleagues are now working to understand how DOC promotes methylation. One possibility is that DOC acts indirectly by increasing bacterial growth, while another is that DOC may directly interact with the mercury itself to boost its ability to enter bacteria.

Although mercury already in the environment is there to stay, Moreau says an understanding of what regulates mercury toxicity is critical for developing ecosystem-level management strategies.

"Strategies to deal with methylmercury production [should] lead to hopefully more efficient ways to reduce human consumption of methylmercury and lead to less potential human health problems," he says.


'/>"/>

Contact: John Moreau
moreau@geology.wisc.edu
University of Wisconsin-Madison
Source:Eurekalert

Related biology news :

1. New study warns limited carbon market puts 20 percent of tropical forest at risk
2. Mice use specialized neurons to detect carbon dioxide in the air
3. Researchers find new taste in fruit flies: carbonated water
4. Studying component parts of living cells with carbon nanotube cellular probes
5. New membrane strips carbon dioxide from natural gas faster and better
6. Green alga genome project catalogs carbon capture machinery
7. Hungry microbes share out the carbon in the roots of plants
8. Decline in uptake of carbon emissions confirmed
9. Study reveals that nitrogen fertilizers deplete soil organic carbon
10. US fires release large amounts of carbon dioxide
11. Wildfire drives carbon levels in northern forests
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:4/13/2017)... Calif. , April 13, 2017 UBM,s ... York will feature emerging and evolving technology ... Both Innovation Summits will run alongside the expo portion ... speaker sessions, panels and demonstrations focused on trending topics ... largest advanced design and manufacturing event will take place ...
(Date:4/11/2017)... April 11, 2017 No two people ... at the New York University Tandon School of ... have found that partial similarities between prints are ... in mobile phones and other electronic devices can ... The vulnerability lies in the fact that fingerprint-based ...
(Date:4/5/2017)... -- Today HYPR Corp. , leading innovator in ... the HYPR platform is officially FIDO® Certified . ... that empowers biometric authentication across Fortune 500 enterprises and ... 15 million users across the financial services industry, however ... suites and physical access represent a growing portion of ...
Breaking Biology News(10 mins):
(Date:9/19/2017)... ... 19, 2017 , ... Participants of this educational webinar will ... Along with the advantages and disadvantages of ductless, filtered fume hoods, they will ... laboratory. , Attendees will learn from an industry expert about the different types ...
(Date:9/19/2017)... ... September 19, 2017 , ... The new and improved Oakton® pocket ... testers even stand upright with a new cap design that is versatile, functional and ... field who need to test water quality. , The Oakton pocket testers have many ...
(Date:9/19/2017)... , ... September 19, 2017 , ... ... pleased to announce the recipients of its 2017 Science Student Award. The scholarship ... qualities, and involvement with community service defray the costs of obtaining their science ...
(Date:9/19/2017)... Charlotte, NC (PRWEB) , ... September 19, 2017 ... ... focusing on band technologies for surgical applications, announced today that two new patents ... System. , Michael Albert, MD, Co-Founder of Band-LOK, said, “We continue to explore ...
Breaking Biology Technology: