Natural radioactivity in alluvial soil of Indo-Gangetic plain

In the earth's crust, the most commonly encountered naturally occurring radionuclides are ²³⁸U, ²³²Th, their decay products and ⁴⁰K. These are also a source of natural external radiation exposure due to their gamma-ray emissions. Their concentration in soil, sand and rocks depends upon their geological and geographical origin. The widely varying content of such radionuclides, prevalent in soils is an essential input for understanding the natural radiation background and any changes in it. During the past decades, agricultural activities in the Indo Gangetic plains of India have widely expanded causing an escalation in the application of inorganic fertilizers and pesticides to increase crop production. Inorganic, especially phosphate (P) fertilizers, contain hazardous elements including, heavy metals (Cd, Cr, and Pb) and radioactive elements (U, Th and their daughters), which are considered to be toxic to human and animal health. These anthroprogenic activities can impact the distribution and bioavailability of radionuclides in the terrestrial environment. In this context, the present work will provide a reference data for estimating the change in environmental radiation levels as these radionuclides can also serve as excellent biochemical and geochemical tracers in the environment