Study Zeros In on Source of Arsenic in Bengal Basin’s Deep Wells


High, harmful concentrations of arsenic are found in aquifers all over the world, but the groundwater of the Bengal Basin, in the northeastern part of the Indian subcontinent, contains the most severe arsenic contamination.

Naturally occurring arsenic is considered a carcinogen and has been linked to miscarriage and infant death, as well as cardiovascular disease and various cancers later in life.

Lamont-Doherty Earth Observatory research professor Lex van Geen has been studying arsenic contamination in drinking water for almost two decades. His earlier collaborations with colleagues in public health and economics urged rural Bangladeshis to use neighboring uncontaminated wells whenever possible. Both the government and individual households then began installing deeper wells, because in most areas only more shallow wells have contamination issues, for geological reasons. However, other studies also found high arsenic contamination in deeper wells in the southwestern Bengal Basin. This arsenic is naturally occurring — not released directly by human activities — and points to deficiencies in the current understanding of the basic mechanisms that regulate arsenic levels in groundwater.

Van Geen is co-author on a new study that explores the cause of arsenic found in deep aquifers in the Bengal Basin and suggests that instead of digging deeper wells to escape arsenic contamination, people in that area should be sharing wells that have been tested and proven to be safe from arsenic. The study is published in Geophysical Research Letters, and was conducted with hydrogeologists at the University of Dhaka in Bangladesh and Indian Institute of Technology Kharagpur in India, along with collaborators from several other U.S. institutions.

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