拉萨河流域水体中锶元素含量、来源及分布特征

Content, Source and Distribution Characteristics of Strontium in Water Body of Lhasa River Basin

采用电感耦合等离子体质谱仪(ICP-MS)Element 2测量拉萨河中下游和堆龙曲支流16个采样点水样中的锶含量,通过统计分析和相关性分析等方法研究水体中锶的来源和分布特征。结果表明,拉萨河水体中锶的质量浓度(88.9μg/L)与世界河流平均值(78μg/L)相当,明显低于黄河、淮河、洪水河、楚拉克阿拉干河和格尔木河等河流。锶的质量浓度在拉萨河中游呈沿程下降趋势,下游呈U型波动趋势,堆龙曲支流呈沿程上升趋势;在地理分布上,锶的质量浓度随纬度的增加而下降,随经度的增加而先上升后下降。拉萨河水体中锶的质量浓度与Ca^(2+)、Mg^(2+)、SO_(4)^(2-)和HCO_(3)^(-)大体上呈正相关关系,而与Na^(+)、K^(+)和Cl^(-)无明显相关关系,表明拉萨河流域锶的含量主要受碳酸盐岩风化作用所控制,硅酸盐岩和蒸发盐岩风化作用的贡献很小。

The contents of strontium in water samples from 16 sampling points in the middle and lower reaches of Lhasa river and Duilonqu tributary were measured by inductively coupled plasma mass spectrometer(ICP-MS) Element 2. The collected water samples are analyzed by hydro-chemical methods such as statistical analysis and correlation analysis, and the contents and distribution characteristics of strontium in water in the study area were obtained. The results show that the mass concentration of strontium in Lhasa river is equivalent to the average value of world rivers, and is significantly lower than that of other rivers such as Yellow river, Huai river, Hongshui river, Chulakalagan river and Golmud river. Strontium mass concentrations of Lhasa river decrease with the increase of distance along the river in the middle reaches, increase with the increase of distance along the river in the Duilonqu tributary, while a U-shaped fluctuation trend is showed in the lower reaches. In geographical distribution, strontium mass concentration decreased with the increase of latitude, and first increased and then decreased with the increase of longitude. The strontium mass concentration in the water body of Lhasa river has a positive correlation with Ca^(2+), Mg^(2+), SO_(4)^(2-)and HCO_(3)^(-), but has no obvious correlation with Na^(+), K^(+)and Cl^(-), indicating that the strontium content in Lhasa river basin is mainly controlled by the weathering of carbonate rocks, and the weathering of silicate rocks and evaporated salt rocks has little contribution.