Toxic Metals in the Water Sources of North Brahmaputra Plain, India

The lower Jia Bharali catchment and adjoining areas in central part of North Brahmaputra Plain (NBP) is characterized by more than 800m thick Older and Younger Alluvium deposited by the west flowing Brahmaputra river and the south flowing trans Himalayan rivers. Unconfined, shallow alluvial aquifers of the area with a general southward flow are largely tapped for domestic use through numerous dug well attached with almost every household. Monitoring of 180 dug wells for two hydrological years show strong seasonal fluctuation of the groundwater table linked to the summer monsoon that brings more than 1500mm precipitation in the area between June- September. This study has presents the first ever systematic database on toxic trace elements viz., As, Cr, Fe, Mn, Ni, Pb and Zn from the water sources in north Brahmaputra plain based on water samples shallow aquifers and surfacewater sources collected in both dry and wet seasons. Due to high potential use of both types of water sources for drinking, cooking and other household purposes, the data was analysed with respect to WHO standards for drinking water.