Winter 2011 | Article by Robert M. Morris
With her latest research highlighted in the leading scientific journal Nature, Professor Karen Johannesson is receiving wide acclaim for her important discoveries about the origin of cancer-causing toxins in the drinking water in India, but her next step will be applying those findings right in Tulane's backyard.
Naturally-occurring arsenic in the groundwater that supplies drinking-water wells in India and Bangladesh is "often called the largest mass poisoning in human history," and is "an environmental crisis that affects more than 60 million people in the Bengal Basin," the Nature article begins. But the exact origins of the arsenic are unclear, and one prominent theory had identified man-made ponds built for flood-control reasons as a possible culprit.
Research by Johannesson, a professor in the School of Science and Engineering's Department of Earth and Environmental Sciences, demonstrates that the ground waters in the most arsenic-contaminated regions are not being fed by those ponds, however, suggesting that the arsenic is coming from materials already in the sediment around the groundwater. Her research doesn't necessarily discredit the pond theory in other contaminated areas, she notes: In the region she was studying, the groundwater is beneath 10 or 20 meters of clay. At other research sites, where the clay is only 2 or 3 meters deep, the ponds may present more of an issue, she said.
"It does make the problem harder, but it also implies there may be other places affected around the world, for example, the Mississippi River," Johannesson said of her findings. "Is it something unique to South Asia, or is it something we see in any of these young major river deltas?"
Elevated arsenic levels have been found in shallow ground waters in Louisiana, and residents of the town of Melville in St. Landry Parish along the Atchafalaya River found high levels of arsenic in its private wells earlier this year. Johannesson plans to send a proposal to the National Science Foundation in early December to study the Mississippi River delta in the same way she studied the Bengal Basin in India.
"Hopefully, the Mississippi will give us a natural laboratory that's closer to home, and that will provide some of these answers," Johannesson said.
The wide-ranging implications of her arsenic research are similar to another project of hers, a study of tungsten in the environment around Fallon, Nevada. Tungsten was once seen as a safe alternative to lead, but Johannesson said that's only because it naturally occurred in concentrations too small to be easily measured. But after unexpectedly high rates of leukemia were recorded in children around the town, researchers found elevated tungsten concentrations in the groundwater near the town — which also has tungsten mining and milling operations — so Johannesson began looking into the source of the metal in the community.
Like the arsenic study, the tungsten problem has implications all over the country. The U.S. military used tungsten bullets for years on its firing ranges, until tungsten started appearing in the groundwater below them. Likewise, it is still a common ingredient in fishing weights — suggesting that its harmful properties could be spread across the Southeast.
"The problem with tungsten is that it was off the radar," Johannesson said. "There have been some studies that suggest it could be very toxic, but we don't really know how tungsten moves through the environment."
That Johannesson's latest research is drawing so much attention is hardly a surprise to Science and Engineering Dean Nick Altiero, who said her talent was evident when the school was recruiting her. She has been extremely successful in securing National Science Foundation funding, and her publications always have an impact, he said.
"She's one of our stars," Altiero said.
For Johannesson, it is no accident that her study of heavy metals has such profound implications for communities across the world. Ever since she was pursuing her doctorate, she said, she wanted her scientific contributions to be measured by how much they help people.
"I made a conscious decision that I wanted to do something that had some societal relevance in terms of human health," Johannesson said, "as well as had scientific interest on its own."
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