Tulane Professor Studying Arsenic Levels in Rural Louisiana Drinking Water

Spring 2016 | Barri Bronston

Karen Johannesson

Tulane University geochemistry professor Karen Johannesson won accolades when in 2011 she and her research team made significant discoveries about the origins of arsenic in drinking water in India.

Johannesson couldn’t help but wonder if her research could be applied closer to home.

“We wondered why no one had researched the same thing in the Mississippi delta,” she said. “We wanted to see if this was a problem here.”

Specifically, they wanted to know whether shallow groundwater in and around the Mississippi River delta also contained high concentrations of arsenic and other cancer-causing toxins, and if so, how they got there.

They keyed in on two areas – one in Bayou Lafourche near Napoleonville and the other in Cow Island, an unincorporated community in Vermillion Parish on the edge of the Mississippi delta. Using methods based on their work in India, they found the presence of arsenic to be at least 10 times higher than EPA standards of less than 10 parts per billion.

Initially researchers believed the arsenic was human-induced, suggesting that pesticides used to kill boll weevil on cotton crops in the mid-20th century were to blame. A more likely cause is the natural presence of arsenic in the sediment around the groundwater.

“It’s consistent with iron reduction and the subsequent release of arsenic,” Johannesson said.

While the amount is significantly less than what she and colleagues found in the Bengal Basin of India, it is alarming nonetheless, as arsenic is associated with such health problems as skin and lung cancer, low birth weight and decreased mental ability in children.

“I’m concerned about people who are living in more rural areas, who very well could be drinking water with high levels of arsenic,” she said.

Johannesson recently learned that her team’s paper on arsenic in shallow groundwater from the Napoleonville site was accepted for publication in the Journal of Hydrology: Regional Studies. Her research in India was highlighted in the leading scientific journal Nature.

Johannesson has won numerous accolades for her work, both on arsenic in groundwater and as well as rare earth elements in the hydrosphere. In 2014, she was named a fellow of the International Association of Geochemistry, and last year, she received the Patterson Medal of the Geochemical Society, which recognizes an innovative breakthrough in environmental geochemistry of fundamental significance.

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