At a research site in the southern part of Bangladesh, scientists calculated that irrigation pumping, which began in the last several decades, has dramatically altered groundwater flow through the aquifer. They show that the resulting changes to the chemistry of the groundwater have the potential to either increase or decrease arsenic levels, in a paper written by an MIT-led team of scientists in the Nov. 22 issue of Science.
"Our data indicate that the arsenic was mobilized largely by degradation of dissolved organic carbon by microbes. Some of the organic carbon appears to have been drawn into the aquifer by irrigation pumping," said Charles F. Harvey, assistant professor of civil and environmental engineering at MIT and lead author of that paper. "But the effects of irrigation are complex, probably lowering arsenic concentrations in other areas. Curtailing irrigation pumping is not a solution."
Harvey is also an author of a research paper providing an epidemiological analysis of arsenic-induced illness throughout Bangladesh. That paper will appear next year in the Water Resources Research journal published by the American Geophysical Union. In it, the authors conclude that replacing 31 percent of the country's most tainted wells with deeper wells will eliminate about 70 percent of the illness, assuming that arsenic levels remain low in the deep wells.
Arsenic poisoning, usually characterized by sores on the chest, or blackened knotty palms, and cases of skin, lung, liver, bladder and pancreas cancers have been linked to arsenic in the drinking water. In 1998 the World Bank agreed to provide Bangladesh a $32.4
Contact: Denise Brehm
Massachusetts Institute of Technology