Research On Corrosion Process And Chemical Composition Of Cuihua Mountain Springs' Water In Qinling Gneiss Area In Shaanxi Province

At home and abroad, research on chemical composition of springs' water is one of the hot problems. At abroad, research mainly concentrates on establishing hydrogeological model and using chemical methods to analyze chemical characteristics of springwater. Under the guidance of Earth system science, domestic scholars have made a large number of studies of basic theory, exploitation and utilization, pollution and governance of springwater, and have achieved fruitful results. However, the past observation of chemical composition of springs' water is mainly concentrated in the limestone and dolomitic area; there is no observation in gneissic area. Gneiss strata developed in Cuihua mountain area of Qinling Mountains, and spring water is acidic, which is different from other areas of northern China. Through two years continuous observation, changes of corrosion process and spring water's chemical composition in this area are mastered, reasons of them are explored. This research enriched the change theory of spring's chemical composition, provided scientific basis for scientific, rational development and utilization of local water resources, land resources, tourism resources, and environmental protection and global change research. At the same time, it is important to the exploration of global carbon cycle and springs' corrosion mechanism.Through continuous observation and data analysis in this area, following conclusions are got.(1) Diurnal variation of springs' pH value and conductivity in Cuihua mountain area is inconspicuous.By comparison, pH variation is slightly larger than conductivity.(2) PH value change of Shuiqiu spring's water in the Cuihua Mountain is between 5.69 and 6.74; the annual mean number is 6.17, taking on a weak acidic character. Conductivity change of Shuiqiu spring is between 180.03μS/cm and 210.00μS/cm; the annual mean number is 196.36μS/cm. Within a year, pH value and conductivity in Shuiqiu spring changes from high to low and then to high again, but the conductivity change is larger, and the time to change smaller is later. Overall, in winter and spring the spring's pH value and conductivity is larger than in summer and autumn.(3) PH value change of Huxi spring's water is between 6.27 and 6.98; the annual mean number is 6.58, taking on a weak acidic character. Conductivity change of Huxi spring is between 155μS/cm and 237μS/cm; the annual mean number is 185.56μS/cm. Within a year, pH value in Huxi spring changes from high to low and then to high again, but the conductivity changes is contrary to pH. Overall, in winter and spring, the springs' pH value is large while conductivity is small; in summer and autumn, pH value is small while conductivity is large.(4) Hydrochemical type of Shuiqiu spring and Huxi spring are mainly HCO₃^- and Ca²⁺,content of them is high, which accounted for more than 95% of the...