Estd.: 1981
Department of Geology, Andhra University, Visakhapatnam- 530 003, India
*Email: suryaraopediredla@gmail.com
Groundwater quality studies has been carried out in Etcherla Mandal, Srikakulam District, Andhra Pradesh, to assess the factors responsible for controlling the fluoride (F-) content in groundwater. The concentration of F- varies from 0.7 to 1.9mg/L. It exceeds the threshold limit of 1.5mg/L recommended for potable water in 52% of the groundwater samples. The results suggest that there is a good positive relation between F and both pH and HCO as well as between Na+ and HCO and a poor positive correlation between Fand TH. It indicates an active dissolution of F- from bedrock minerals due to alkalinity rather than hardness. The occurrence of clays favours active solubility and dissolution of F bearing minerals as well as active anion exchange between F-and OH-. The higher rate of evaporation causes an increase of F- in the groundwater due to precipitation of CaCO and dissolution of CaF to keep the chemical equlibria. Further, a positive correlation of F with K+, SO 2- and NO – suggests that the usage of uncontrolled agro-chemicals for higher crop yields is also a source of F- in the groundwater. The study suggests management measures to mitigate F content in the drinking water.
Keywords: Fluoride, Groundwater, Etcherla Mandal, Srikakulam District, Andhra Pradesh