Featured Research

from universities, journals, and other organizations

Arsenic Contamination Lacks One-size-fits-all Remedy

Date:
December 11, 2007
Source:
University of Wisconsin-Madison
Summary:
Though a worldwide problem, arsenic contamination of drinking water does not have a universal solution.

Though a worldwide problem, arsenic contamination of drinking water does not have a universal solution.

Instead, recent work by University of Wisconsin-Madison researchers on arsenic-tainted wells shows that appropriate treatment varies depending on the source of the contamination.

Naturally occurring arsenic in rocks is usually associated with sulfur- or iron-rich minerals, where it poses no threat to groundwater, explains lead researcher Madeline Gotkowitz, a hydrogeologist at the Wisconsin Geological and Natural History Survey.

Once it is released from mineral form into groundwater through geochemical or biological processes, however, chronic exposure to arsenic has been linked to skin lesions and increased risk of several cancers. The issue has gained international prominence in Southeast Asia but affects populations around the world.

"It's stunning how many people worldwide are affected by toxic levels of arsenic," Gotkowitz says. "There are thousands upon thousands of people who become ill from having their drinking water contaminated with arsenic."

Though on a smaller scale, arsenic-tinged groundwater is a problem in parts of the United States as well, including regions in the Northwest, East and Midwest.

Management practices in Wisconsin have been complicated by two competing sources of soluble arsenic, Gotkowitz says. Arsenic associated with sulfide minerals in rock can be released by the weathering effects of oxygen-rich environments.

Alternately, arsenic bound to iron oxides can be released by iron-reducing bacteria, which thrive in low-oxygen conditions. "There is different geochemistry in different [areas]," Gotkowitz says. "That makes it a harder nut to crack. ... People might have a similar symptom - arsenic in their water - but there are different solutions because the geologic environment is quite different."

In Wisconsin, groundwater arsenic affects some municipal water supply wells, but it is primarily an issue for rural communities and others where residents often rely upon shallow private wells.

"Large areas of Outagamie and Winnebago counties have high arsenic levels in one of the shallower aquifers," Gotkowitz says. "Upwards of 10,000 private homes are affected by having arsenic above the standard [acceptable level]."

Wells are routinely disinfected with chlorine bleach to control pathogenic and other bacteria. However, such treatment raises questions in regions with arsenic problems.

While bleach should kill off arsenic-producing bacteria, it also creates a high-oxygen environment that some worry could enhance release of additional arsenic from the rocks.

Gotkowitz and UW-Madison geologists Eric Roden and Evgenya Shelobolina evaluated the impact of chlorination on bacteria and arsenic levels in Wisconsin wells.

The results were presented at the American Geophysical Union meeting in San Francisco today (Dec. 10).

In wells with arsenic levels only moderately above the accepted standard, the scientists found that the presence of iron-reducing bacteria was associated with higher arsenic concentrations. Disinfection of these wells with chlorine adequately removed bacteria and reduced arsenic levels in the short term.

In addition, chlorination did not increase arsenic release from the surrounding rocks, showing that oxidation of the rocks is not an important source of arsenic here.

Similar effects were seen in areas with a relatively high water table, where aquifers are exposed to less oxygen.

The results suggest that disinfection is an effective way to control pathogenic bacteria and may also limit arsenic release in wells under these conditions.

"It's not like there's going to be an easy solution, but there are some basic indicators," Gotkowitz says. Under low-oxygen conditions or where water levels are high, "you might want to try to control those types of bacteria as a way to improve well water quality."

Chlorine treatment may not be appropriate in all environments, however. For example, she says, the oxidizing properties of bleach may pose more of a concern in arsenic-affected regions with lower water tables, while wells drawing from aquifers highly contaminated with arsenic are unlikely to benefit from localized treatment.


Story Source:

The above story is based on materials provided by University of Wisconsin-Madison. Note: Materials may be edited for content and length.


Cite This Page:

University of Wisconsin-Madison. "Arsenic Contamination Lacks One-size-fits-all Remedy." ScienceDaily. ScienceDaily, 11 December 2007. <www.sciencedaily.com/releases/2007/12/071210214711.htm>.
University of Wisconsin-Madison. (2007, December 11). Arsenic Contamination Lacks One-size-fits-all Remedy. ScienceDaily. Retrieved August 29, 2014 from www.sciencedaily.com/releases/2007/12/071210214711.htm
University of Wisconsin-Madison. "Arsenic Contamination Lacks One-size-fits-all Remedy." ScienceDaily. www.sciencedaily.com/releases/2007/12/071210214711.htm (accessed August 29, 2014).

Share This




More Earth & Climate News

Friday, August 29, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Raw: Volcano Erupts on Papua New Guinea

Raw: Volcano Erupts on Papua New Guinea

AP (Aug. 29, 2014) Several communities were evacuated and some international flights were diverted on Friday after one of the most active volcanos in the region erupts. (Aug. 29) Video provided by AP
Powered by NewsLook.com
Killer Amoeba Found in Louisiana Water System

Killer Amoeba Found in Louisiana Water System

AP (Aug. 28, 2014) State health officials say testing has confirmed the presence of a killer amoeba in a water system serving three St. John the Baptist Parish towns. (Aug. 28) Video provided by AP
Powered by NewsLook.com
Scientists Have Figured Out Why Rocks Move In Death Valley

Scientists Have Figured Out Why Rocks Move In Death Valley

Newsy (Aug. 28, 2014) The mystery of the moving rocks in Death Valley, California, has finally been solved. Scientists are pointing to a combo of water, ice and wind. Video provided by Newsy
Powered by NewsLook.com
Big Waves, Minor Flooding from Hurricane

Big Waves, Minor Flooding from Hurricane

AP (Aug. 27, 2014) Thundering surf spawned by Hurricane Marie pounded the Southern California coast Wednesday, causing minor flooding in a low-lying beach town. High surf warnings were posted for Los Angeles County south through Orange County. (Aug. 27) Video provided by AP
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