KharagpurResearchers have found why groundwater across one of the world’s most populated river basins is frequently contaminated with toxic elements. A new study of the Brahmaputra River Basin in Northeast India has identified how the physical arrangement of sand and clay deep underground dictates whether a village’s well water is life-sustaining or potentially lethal. For decades, the Brahmaputra River Basin has been known as a hotspot for groundwater contamination, but the distribution of these toxins has remained frustratingly unpredictable. This oxygen keeps toxic elements like arsenic, nickel, iron, and manganese locked onto the surface of minerals. This causes the minerals to dissolve, releasing the trapped arsenic and nickel directly into the groundwater.