The element occurs naturally but is linked to health problems such as cancer and heart defects
Researchers at North Carolina State University are estimating that thousands of wells in North Carolina—and more than one million wells in the Southeast—have high levels of manganese.
The element occurs naturally in soil; however, studies have linked long-term exposure to it with health problems such as cancer and heart defects.
According to Matt Polizzotto, associate professor of crop and soil sciences at the university, water containing more manganese than allowed in accepted water quality standards may have a distinct taste or stain clothes.
"There are some signs that you can look for," he said. "Brown or black stains on your dishwasher or any kind of discoloration of clothes can be indicative. ... And then also sometimes you can get kind of black materials that are accumulating in pipes."
He also recommended that anyone suspecting high manganese levels in their wells should have the wells tested. However, contamination with the element is not an immediate threat.
"The concentrations of manganese that are observed are not anything that's going to harm someone right away," he said. "With natural contaminates, it often takes a long time of exposure before concentrations accumulate to cause these health impacts."
Polizzotto also commented that clothing and dishwasher stains are not necessarily indicators of levels of manganese high enough to lead to health problems.
Piedmont geology is the suspected culprit in the tendency for manganese contamination shown in area wells. Elizabeth Gillispie, Ph.D. student at NC State and lead author of the paper, explained that breakdown of bedrock causes manganese to become concentrated in saprolite—the geological layer located between the bedrock and the layer of soil close to the water table. The saprolite is North Carolina is extra porous, which allows more manganese to seep into well water.
Researchers made their estimates using census data regarding locations of wells in addition to groundwater monitoring data.
In addition to more testing of wells, they also recommend digging any new wells deeper into the earth, farther from the contaminated saprolite.