WaterReducing exposure to groundwater arsenic

Published 12 October 2011

Well diggers in Bangladesh will soon be able to take advantage of a cell phone-based data system, developed at the Earth Institute, to target safe groundwater aquifers for installing new wells that are not tainted with arsenic

Well diggers in Araihazar, Bangladesh, will soon be able to take advantage of a cell phone-based data system, developed at the Earth Institute, to target safe groundwater aquifers for installing new wells that are not tainted with arsenic. Using a new needle sampler (also developed at the Earth Institute), they will also be able to test whether the water is safe during drilling and before a well is actually installed.

A Columbia University release reports that recent estimates show that more than 100 million people in rural South Asia, from India to Vietnam, regularly use water containing unsafe levels of arsenic. The water they drink, usually from shallow wells, can cause debilitating lesions, deadly internal cancers, and was recently shown to affect neurological development in children. From their 25-square-kilometer study area in the Araihazar upazila, Earth Institute researchers have spent five years studying better ways of providing safe drinking water in rural Bangladesh by considering all relevant factors, including public health, geology, engineering, social science, policy and decision making. Three newly published research papers illustrate the effectiveness of this unusual research collaboration.

We hope these new technologies will assist the rural population of Bangladesh, with support from the government of Bangladesh and international agencies, to address the serious health crisis in Bangladesh caused by drinking groundwater containing elevated arsenic levels,” says Alexander van Geen, senior researcher with the Lamont-Doherty Earth Observatory.

The phone-in data system will use new statistical procedures developed by Columbia statistics professor Andrew Gelman and colleagues to estimate the likelihood of a particular location in the Araihazar having low-arsenic water at a given depth. The approach was first tested in Columbia’s study area and, after successful results, will now be expanded to an area that is six times larger on the basis of 29,000 well tests compiled by the Bangladesh Water Supply and Mitigation Program. Gelman’s work was recently published in the journal Risk Analysis.

This is an interesting example for decision analysis because decisions must be made locally, and the effectiveness of various decision strategies can be estimated using direct manipulation of data, bypassing more formal statistical modeling,” said Gelman.

After the well diggers select a site, they will be able to sample the water without actually installing a well by using an inexpensive, new device called the needle sampler that is made primarily out of inexpensive industrial materials readily available in Bangladesh. This will avoid the wasted effort and expense of digging a tube well that turns out to contain unsafe water.

The paper demonstrating the effectiveness of the needle-sampling technique was recently published in the journal Environmental Science and Technology. In the article, van Geen and his colleagues at the Lamont-Doherty Earth Observatory and the University of Dhaka, who developed the needle sampler, explain that it takes no more than an hour to use and could be deployed by the well-digging teams currently trained to install tube wells in Bangladesh.

Drawing on his experience in Bangladesh, van Geen writes, “It is unrealistic to expect the hundreds of teams of drillers operating in Bangladesh to include a field kit for arsenic … as well as the needle sampler with their standard equipment soon. What is conceivable at an early stage is the systematic use and refinement of the device by engineers working for the Bangladesh government as well as nongovernmental organizations involved in arsenic mitigation in Bangladesh.”

Van Geen and the Earth Institute’s arsenic mitigation team, as a result of their interdisciplinary research, have become proponents of installing deep, shared community wells in safe aquifers as the most viable option for helping Bangladeshi villagers out of their current arsenic crisis. They also recommend that mechanized irrigation pumps be banned from tapping into the deep, safe aquifers identified for the shared tube wells. Research was funded by the National Institute of Environmental Health Sciences (NIEHS) Superfund Basic Research Program and the Earth Institute.