Environmental Engineer Works To Resolve Arsenic Poisoning In Bangladesh Water Supplies

In a typical year, over 70 percent of the country is flooded during the monsoon season. But even though surface water is abundant, it's usually polluted and not safe to drink. To reduce the health risks, Bangladesh has converted most of its drinking water supply from surface water supplies to groundwater wells.

Tragically, those wells may be responsible for the largest mass arsenic poisoning in history. Groundwater throughout Bangladesh and West Bengal in India is contaminated with naturally occurring arsenic from the sediments that form the region's aquifers. It has been estimated that 75 million people are at risk of developing health effects associated with the ingestion of arsenic.

"This is an environmental problem of enormous magnitude. Over one million wells are contaminated," said Islam, who added that the problem has only surfaced in recent years.

UNICEF led the effort to switch from surface water to groundwater sources after the 1950s in response to epidemics of cholera, dysentery and a high infant mortality rate. The initiative worked, but with unforeseen consequences. Many of the new wells contain water with arsenic concentration of 500 to 1000 parts per billion and some as high as 2,000 parts per billion of arsenic. The allowable standard in the United States is just 50 ppb.

The British Geological Survey is completing a detailed survey of groundwater contamination, which will set the stage for Islam's research. Their results show widespread contamination, but also an unusual pattern. Shallow wells are more contaminated than deeper wells. "Our role is to find out why the levels are so high. There are other areas of the world with similar arsenic levels in the sediment, but it doesn't get into the groundwater. We want to find out why it's so mobile in the Ganges basin."

Working with collaborators at the Massachusetts Institute of Technology, the University of Tokyo, ETH in Switzerland, and the Bangladesh University of Engineering and Technology, Islam will explore two research questions:

"Our first research question is: Why are arsenic concentrations so high in the groundwater of Bangladesh? Once we have developed an understanding of the cause of high arsenic concentrations we will consider a second question: How will arsenic concentrations change over time and space?"

The field project, funded by a three-year, $400,000 grant from the National Science Foundation, includes 16 test wells drilled from 25 feet down to 500 feet below the surface. The researchers will look at how arsenic level and the form of arsenic changes at different depths over time.