Multivariate statistical interpretation on seasonal variations of fluoride-contaminated groundwater quality of Lalganj Tehsil, Raebareli District (UP), India

Quality of groundwater is concerned with various processes such as precipitation, weathering and dissolution of mineral, cation exchange and ground water exploitation. Present study aims to interpret the seasonal variation of groundwater quality contaminated with fluoride. Sixty water samples were collected during pre- and post-monsoon seasons from Lalganj Tehsil of Raebareli District, UP (India). Multivariate statistical analyses such as factor analysis (FA), principal component analysis (PCA), cluster analysis and correlation matrix were applied on 14 hydro-chemical constituents, i.e., pH, EC, TDS, TBDT, TH, bicarbonate (BiC), NO 3 − , SO 4 2− , F − , Cl − , Ca 2+ , Mg 2+ , Na + and K + . Factor analysis explained that TH, Mg 2+ , SO 4 2− , Cl − , EC, TDS and F − were significantly loaded parameters during both seasons that influence the groundwater quality due to weathering and dissolution of mineral during aquifer recharging. The source of F − appears to be geogenic due to the alluvial sediments deposited in the geological past as no hard rock terrain was present in the nearby areas that were dominantly made up of mud with pocket of sand. The cumulative variance obtained from PCA suggested that the groundwater quality in pre-monsoon was better than that of post-monsoon. Correlation explained that EC of groundwater completely depends on the dissolved solids. Dendrogram of cluster analysis indicated that parameters were grouped into four clusters on the basis of similarity, during both seasons. Values of Mg + , F − , TH, and TDS exceeded more than the drinking water standard during both seasons. It will bring alertness to the people regarding whether the groundwater is suitable or unsuitable for drinking purpose.