4. Results
The chemical parameters,87Sr/86Sr ratios and δ11B values of the analyzed samples are given in Table 1. The pH in water samples shows a narrow range (7.32-8.85), with a mean value of 8.08 ± 0.36 (Table 1). The TDS of all water samples varied considerably from 356.7 to 11296 mg/l (Table 1), with a general increase from the source region to downstream. The source groundwater with low TDS is dominated by Mg-Ca-Na-HCO3 type, while the upstream groundwater and river water were saline water with a Na-Mg-Cl-SO4 -type facies. Cl/Br ratios of source groundwater samples ranged from 409.0 to 519.3. The upstream groundwater and river water samples had a relatively steady trend of Cl/Br ratios, ranging from 1242 to 2405. Ca and Mg concentrations of these water samples are well correlated to SO4, with (Ca+Mg)/SO4 ratio of most saline water samples close to 1. The Mg/Ca ratio of saline water samples generally exceeds 1, which indicates the enrichment of Mg with water salinization.
Strontium concentrations and87Sr/86Sr ratios in groundwater ranged from 0.5 to 9.9 mg/l, and from 0.710903 to 0.711784, respectively. The upstream groundwater samples had a higher strontium concentration and higher 87Sr/86Sr ratios than source groundwater. The strontium concentration of river water samples varied between 4.2 and 11.1 mg/l, with87Sr/86Sr ratios between 0.710916 and 0.711427. The river water presents higher Sr contents and lower87Sr/86Sr values compared to that of upstream groundwater (Table 1). The Strontium concentrations are in a relatively narrow range (0.23-0.53) in the soil samples (water-soluble) collected from riverbanks, while the87Sr/86Sr ratio varied between 0.710912 and 0.713937 with an increasing trend from mountaintop to the foothills. Strontium correlated well with Calcium and Chlorine in brackish water samples. The Sr/Cl ratio of source groundwater samples ranged from 0.034 to 0.036 and is significantly higher than that of the upstream groundwater (0.002-0.007). The Sr/Ca ratio of water samples also presents a systematic increase with water salinization.
Values of δ11B in water are highly variable and ranged from -5.79‰ to +3.47‰, from -8.35‰ to -5.77‰, from +11.48‰ to +23.17‰ and from +17.45‰ to +37.32‰ for precipitation, the source groundwater, the upstream groundwater and the river water, respectively. The Boron isotope ratios of the river water samples displayed a broader range (17.45‰ to 37.32‰) relative to upstream groundwater (11.48‰ to 23.17‰) (Table 1), but still lower than the δ11B values of seawater (39.5±1‰) (Vengosh et al., 1994). The river suspended particulates samples had δ11B values of 3.50‰ to 5.42‰. The δ11B values of soil samples collected from profiles under water and acid treatment were from -2.13‰ to +5.66‰ and from 0.60‰ to 7.42‰, respectively (Table 1).