Zhang Qing-Hua, Sun Ping-An, He Shi-Yi, Wen Hua, Liu Ming-Long, Yu Shi
College of Environmental Science and Engineering, Guilin University of Technology, Guilin 541004, China.
Key Laboratory of Karst Dynamics, Ministry of Land and Resources/Guangxi, Institute of Karst Geology, Chinese Academy of Geological Sciences, Guilin 541004, China.
Huan Jing Ke Xue. 2018 Mar 8;39(3):1065-1075. doi: 10.13227/j.hjkx.201706239.
In order to understand the temporal and spatial variations of major ions in water and their sources in the Lhasa River Basin, water samples were collected monthly at the hydrological station in the Lhasa River from August 2014 to July. The results show that HCO is the dominant anion in the water of the Lhasa River, which accounts for 68.73% of the anions, followed by SO. Ca is the dominant cation, which accounts for 67.75% of the cations, followed by Mg. The pH values of the river water range between 8.31 and 8.90, with a mean of 8.59 throughout the year, generally showing alkaline water. The highest pH values occur in summer, which is probably due to the photosynthesis of aquatic plants and the growth of phytoplankton. Electrical conductivity (EC) varies between 155.0 and 257.0 μS·cm, with a mean of 210.5 μS·cm. Because of the frequent uplift of the Tibetan Plateau that enhanced the mechanical weathering of rocks and mineral dissolution, the total dissolved solid (TDS) concentration, at an average of 181.35 mg·L, is significantly higher than the average value of rivers around the world. The Lhasa River is recharged by surface runoff, so the concentrations of major ions in water are higher during winter, but lower in summer. An ion source analysis indicates that Ca, Mg, and HCO are mainly derived from chemical weathering of carbonate minerals, Cl, SO, and NO are mainly affected by precipitation and rock weathering. Furthermore, the concentrations of major ions in the water have a negative correlation with the river discharge rate, which suggests there might be a dilution effect occurring during the rainy season.
为了解拉萨河流域水体中主要离子的时空变化及其来源，于2014年8月至次年7月在拉萨河的水文站每月采集水样。结果表明，HCO是拉萨河水中的主要阴离子，占阴离子总量的68.73%，其次是SO。Ca是主要阳离子，占阳离子总量的67.75%，其次是Mg。河水的pH值在8.31至8.90之间，全年平均为8.59，总体呈碱性水。pH值最高出现在夏季，这可能是由于水生植物的光合作用和浮游植物的生长。电导率（EC）在155.0至257.0 μS·cm之间变化，平均为210.5 μS·cm。由于青藏高原的频繁隆升增强了岩石的机械风化和矿物溶解，总溶解固体（TDS）浓度平均为181.35 mg·L，显著高于世界其他河流的平均值。拉萨河由地表径流补给，因此水中主要离子的浓度在冬季较高，而在夏季较低。离子源分析表明，Ca、Mg和HCO主要来源于碳酸盐矿物的化学风化，Cl、SO和NO主要受降水和岩石风化的影响。此外，水中主要离子的浓度与河流流量呈负相关，这表明在雨季可能存在稀释效应。
