Geochemical evaluation of fluoride and nitrate contamination in groundwater using graphical method, Karnataka state, India

Abstract

Nitrate and fluoride contamination in groundwater is one of the major emerging problems of the Northern- Karnataka region of India. Fluoride pollutants in groundwater are responsible for dental and skeletal fluorosis whereas nitrate contamination is highly responsible for methemoglobinemia (blue baby disease), respiratory system, kidney, and thyroid in children as well as adults. The study has been carried out to identify the geochemical processes and mechanism responsible for releasing nitrate and fluoride pollutions in the region. Sampling has been done in both monsoon periods such as pre-monsoon and post-monsoon seasons. Fluoride concentration varies from 0.65 mg/L to 1.97 mg/L in pre-monsoon whereas the nitrate concentrations vary from 12 mg/L to 96 mg/L. The post-monsoon sample shows that the fluoride and nitrate vary from 0.76 to 1.53 mg/L and 16 mg/L to 77 mg/L respectively. The worst fluoride-affected villages are Jidga, Kamanalli, Padsawli, Sakkarga, and Nagelagaon. Several diseases such as dental and skeletal fluorosis have been identified in the region. Intertrappean beds and enhance the rate of weathering of fluoride bearing minerals may be responsible for fluoride contamination whereas excess use of fertilizer is generally responsible for nitrate contamination in the region.