Hydrochemical characteristics and groundwater quality appraisal for irrigation uses in the Lan-gan region, Northern Anhui Province, East China

Abstract

Lan-gan region, one of traditional agricultural production base in northern Anhui Province, East China, has rare hydrochemical reports on the formation mechanism and irrigation assessment of the Quaternary deeper confined groundwater aquifer. To better master hydrochemical characteristics, solute source, and irrigation properties, twenty-five water samples were collected from individual wells. The Gibbs diagram, Piper diagram, ionic ratio, and multivariate statistical analysis were carried out to delineate the hydrochemical facies and water-rock interactions. Meanwhile, USSL and Wilcox diagrams, and irrigation water quality indices were conducted to illustrate the suitability for irrigation. The results indicate that cations and anions are in the order of Ca2+ .Na+ .Mg2+ .K+ and HCO3 - .SO4 2- .Cl-, respectively. Ca-HCO3 is the main hydrochemical type. Water-rock interactions include silicate weathering, carbonate dissolution, halite dissolution and sulfate dissolution. Based on electrical conductivity (EC) value, the majority of the samples are permissible for irrigation, whereas only 12% of the samples were found good for irrigation. The risidual sodium carbonate (RSC), sodium adsorption ratio (SAR), and percentage sodium (%Na), combined with Wilcox and USSL diagrams, demonstrate that the groundwater samples are permissible for irrigation purposes.