Appraisal of groundwater quality in a crystalline aquifer: a chemometric approach

The purpose of this study is to assess the groundwater quality and identify the processes that control the groundwater chemistry in a crystalline aquifer. A total of 72 groundwater samples were collected during pre- and post-monsoon seasons in the year 2014 in a semi-arid region of Gooty Mandal, Anantapur district, Andhra Pradesh, India. The study utilized chemometric analysis like basic statistics, Pearson’s correlation coefficient ( r ), principal component analysis (PCA), Gibbs ratio, and index of base exchange to understand the mechanism of controlling the groundwater chemistry in the study area. The results reveal that groundwater in the study area is neutral to slightly alkaline in nature. The order of dominance of cations is Na + > Ca 2+ > Mg 2+ > K + while for anions, it is HCO_3^->Cl^- > NO_3^- > SO_4^2- > CO_3^2->F^- in both seasons. Based on the Piper classification, most of the groundwater samples are identified as of sodium bicarbonate ( Na^+-HCO_3^-) type. According to the results of the principal component analysis (PCA), three factors and two factors were identified pre and post monsoon, respectively. The present study indicates that the groundwater chemistry is mostly controlled by geogenic processes (weathering, dissolution, and ion exchange) and some extent of anthropogenic activities.