Hydrogeochemical characterization and water quality assessment in Altay, Xinjiang, northwest China.

The safety of drinking and irrigation water is an issue of great concern worldwide. The rational development and utilization of water resources are vital for the economic and societal stability of Altay, an extremely arid area. In this study, three types of water samples (25 river waters, 10 groundwaters, 6 lake waters) were collected from main rivers and lakes in Altay and analyzed for electrical conductivity, total dissolved solids, pH, major ions (i.e., K, Na, Ca, Mg, HCO, Cl, SO, NO, NO, F), and trace elements (i.e., Al, Li, B, Sc, Ti, Mn, Co, Ni, Cu, Zn, As, Se, Rb, Sr, Mo, I, Ba, U). The water quality index (WQI), hazard quotient, carcinogenic risk, Na percentage, and Na adsorption ratio were then calculated to evaluate the water quality for drinking and irrigation. The results showed that the main hydrochemical type of river waters and groundwaters was Ca-HCO, whereas that of lake water was mainly Na-SO. The WQIs (9.39-170.69) indicated that the water quality in Altay ranged from poor to excellent. The concentrations of As, Ni, and U need to be carefully monitored since their average carcinogenic risks (for all waters collected, for adults) reached 0.05686, 0.06801, and 0.14527 and exceeded the safety risk levels (10-10) by at least 568 times, 680 times, and 1452 times, respectively. The result of Na% and SAR indicated that lake waters (with Na% of 62.92 and SAR of 41.63) and groundwaters (with Na% of 37.88 and SAR of 5.58) in Altay were unsuitable for irrigation, while river water (with Na% of 29.24 and SAR of 3.33) could meet the irrigation quality requirements. The results of this study could help promote reasonable water resource use among three types of waters and population protection in Altay.