Wang Peng, Shang Ying-Nan, Shen Li-Cheng, Wu Kun-Yu, Xiao Qiong
Key Laboratory of the Three Gorges Reservoir Region's Eco-environments (MOE), School of Geographical Science, Southwest. University, Chongqing 400715, China.
Huan Jing Ke Xue. 2013 Mar;34(3):874-81.
Freshwater lake of the Tibetan plateau has great ecological value and extreme vulnerability. The water samples have been collected in Daggyaima Co at an altitude of 5 080 m +/- 10 m. This study has investigated the sources, the major controlling factors of the major ions, and hydrochemical evolution trend according to the hydrochemical composition of water samples. The results showed that the major cations and anion of lake water were Ca(2+), Na(+) and HCO3(-), respectively, and the hydrochemical type was HCO3 -Ca, The total dissolved solid (TDS) was in the range of 71.2-199.8 mg x L(-1). The concentrations of EC, Ca(2+) and HCO3(-) in water samples from Southeast areas were relatively low resulted from the rich aluminum and poor calcium of geological background and the dilution effect of surface runoff. The Na(+)/(Na(+) + Ca(2+)) of water samples was 0.08-0.75, Cl(-) /(Cl(-) + HCO3(-)) was 0.11-0.35, Ca/Na was 0.58, Mg/Ca was 0.12, and HCO3/Na was 1.46, which suggested that the hydrochemical composition of the lake water was mainly controlled by silicate rock weathering based on Gibbs model and analysis of elemental stoichiometry. The minerals participated in weathering processes included plagioclase (anorthite, albite), potassium feldspar, biotite, calcite, dolomite, gypsum, rock salt, etc. The average value of K/Na was 0.059, indicating the weathering level of potassium feldspar was relatively low. The saturation index (SI) of calcite, dolomite, gypsum, quartz and hematite contained in the lake was higher than zero, while the SI of rock salt was lower than 0, revealing the trend that the freshwater lake is turning into salt water lake in Tibetan Plateau.
青藏高原的淡水湖具有重大生态价值且极度脆弱。已在海拔5080米±10米的达格亚玛错采集了水样。本研究根据水样的水化学组成，调查了主要离子的来源、主要控制因素以及水化学演化趋势。结果表明，湖水的主要阳离子和阴离子分别为Ca(2+)、Na(+)和HCO3(-)，水化学类型为HCO3 -Ca，总溶解固体（TDS）在71.2 - 199.8毫克·升(-1)范围内。东南部地区水样中EC、Ca(2+)和HCO3(-)的浓度相对较低，这是由于地质背景中铝含量丰富而钙含量低以及地表径流的稀释作用。水样的Na(+)/(Na(+) + Ca(2+))为0.08 - 0.75，Cl(-) /(Cl(-) + HCO3(-))为0.11 - 0.35，Ca/Na为0.58，Mg/Ca为0.12，HCO3/Na为1.46，根据吉布斯模型和元素化学计量分析表明，湖水的水化学组成主要受硅酸盐岩风化控制。参与风化过程的矿物包括斜长石（钙长石、钠长石）、钾长石、黑云母、方解石、白云石、石膏、岩盐等。K/Na的平均值为0.059，表明钾长石的风化程度相对较低。湖水中方解石、白云石、石膏、石英和赤铁矿的饱和指数（SI）高于零，而岩盐的SI低于零，揭示了青藏高原淡水湖正演变为咸水湖的趋势。
