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).