Quality Assessment of Groundwater from the Coal Bearing Aquifer in the Xinji Coalfield, Anhui Province, China

Abstract

In this study, a total of 50 groundwater samples from the coal-bearing aquifer in the Xinji coalfield (one sub-coalfield of the Huainan coalfield) have been collected, and their major ion concentrations have been measured for the evaluation of its suitability for drinking and irrigation, and then the mechanism controlling the water chemistry have been analysed. The results indicate that the groundwater samples are slightly alkaline with TDS higher than the freshwater (<1000 mg/L), and most of them are classified to be Cl- and HCO3- types. The groundwater samples have WQI range from 5.63 to 179 (mean = 64.9), suggesting that these samples are good for drinking. However, the results of sodium adsorption ratio and residual sodium carbonate indicate that only a few of the samples can meet the requirement of irrigation, but must be treated before application. Gibbs diagram and the relationships between major ions, as well as the factor analysis, imply that water-rock interaction is the main process controlling the groundwater chemistry, including the dissolution of evaporate minerals and the weathering of silicate minerals.

Keywords

• quality assessment, groundwater quality, coal bearing aquifer, xinji coalfield