Monitoring 51 community wells in Araihazar, Bangladesh, for up to 5 years: Implications for arsenic mitigation

Abstract

In order to reduce the exposure to As naturally occurring in shallow groundwater of the Bengal Basin, tens of thousands of tubewells tapping deeper aquifers of the Bengal Basin have been installed. We address here lingering concerns that As concentrations in deep tubewells might increase over time with monitoring data spanning a period of up to 5 years for 51 community wells, 115–545 ft (34–164 m) deep, installed in Araihazar upazila, Bangladesh. This exceptionally detailed data set shows that all but 4 of these community wells have consistently provided drinking water that meets the Bangladesh standard for As in drinking water of 50 μg L^{− 1}; all but 10 community wells have also consistently met the World Health Organization (WHO) guideline for As of 10 μ g L^{− 1}. Groundwater pumped from one third of the community wells does not meet the current WHO guideline for Mn in drinking water of 0.4 mg L^{− 1}, although Mn concentrations are lower than in most surrounding shallow wells. In addition to As and Mn, concentrations of 10 elements (Cr, Ni, Cu, Cd, Ba, Hg, Mo, Sb, Pb, and U) out of a total 19 inorganic constituents of potential health concern were monitored and found to be below their respective guideline values established by WHO. Further study is required to evaluate the health consequences of Mn exposure, but the increase in As concentrations in 4 community wells indicates that all deeper tubewells should be periodically re-tested.

Keywords:

• Arsenic
• groundwater
• Bangladesh
• mitigation
• hydrogeology
• monitoring

Acknowledgments

Our long-term study in Araihazar supported by the United States NIEHS/Superfund Basic Research Program through grant P42 ES10349 involves many other colleagues, including Joseph Graziano, Habibul Ahsan and Mary Gamble at Mailman School of Public Health and Yan Zheng and Martin Stute at Lamont-Doherty Earth Observatory. The actual cost of installing and monitoring the community wells was funded by the Earth Institute at Columbia University. The burden of collecting monitoring samples during the initial years was shared with M. Shamsudduha and Mohammad Abdul Hoque. This is Lamont-Doherty Earth Observatory contribution number 7076.