Major Ion Chemistry and Quality Assessment of Groundwater in and Around a Mountainous Tourist Town of China

Groundwater is widely used for various purposes over the world. To investigate the quality of groundwater for domestic and agricultural purposes in a mountainous tourist town of China, nine groundwater and three river water samples were collected during June 2015 for analysis of major ions (K+, Na+, Ca2+, Mg2+, HCO3 −, SO4 2−, Cl−, and CO3 2−), pH, total dissolved solids, electric conductivity, and total hardness. The sources of major ions were discussed in detail by correlation analysis and bivariate diagrams. Sodium adsorption ratio, residual sodium carbonate, soluble sodium percentage, permeability index, and Kelley’s ratio were applied for irrigation water quality assessment. Physiochemical parameters were also compared with the WHO and national standards for domestic purpose. The results demonstrate that both groundwater and river water are fresh water. The abundance of cations in collected water samples is Ca2+ > Na+ > Mg2+ > K+, while that of anions is HCO3 − > SO4 2− > Cl−. All major ion concentrations except CO3 2− in groundwater are higher than those in the river water because of more contacts with rocks and more mineral dissolution in the groundwater. Groundwater in the study area is mainly of SO4·Cl–Ca·Mg type and HCO3–Ca·Mg type, and river water is of SO4·Cl–Ca·Mg type. Groundwater and river water in the study area are both controlled mainly by rock weathering. The dissolutions of halite, carbonates, and silicates, as well as cation exchange and human activities such as fertilizer application in agriculture, geothermal bathing, and tourism are drivers for the variation of major ions in the water. Groundwater is generally suitable for domestic uses except some local samples experiencing low pH and high hardness. Both groundwater and river water in the study area are suitable for irrigation. Land irrigated rationally with such water will have no salinity and alkali hazards.