Impact of geohydrology and neotectonic activity on radon concentration in groundwater of intermontane Doon Valley, Outer Himalaya, India

Radon concentration was measured in 133 water samples from tubewells, handp umps, dug wells and springs of the Doon Valley, Outer Himalaya, India. The observed radon values were found to vary from 10 to 154 Bq/l whereas radium in selected water samples varied from 0.11 to 0.75 Bq/l. Three different c lusters of high radon values were observed in the north-western, central an d southeastern parts of the Doon Valley. These clusters were found to be as sociated with tectonics (thrust/fault) and associated uranium mineralizatio n in the area. In general, radon concentration in groundwater was found to be positively correlated with the depth of the wells, whereas no significan t correlation was observed between radon concentration in groundwater and t he water temperature, pH value, conductivity and altitude of the water samp les. An attempt has also been made to determine the nature and extent of aq uifers in the Doon Valley on radon concentration in groundwater. The variat ion in radon concentration within the groundwater of the study area was fou nd to be controlled by the neotectonic activity and geohydrological process es that occur in the area. The impact of these activities on radon concentr ation in groundwater are discussed.