塔里木河流域出山径流水化学特征研究

本文以区域地质为背景，对塔里木河流域山区径流水化学组分特征进行分析，探讨溶质的来源及其控制因素.结果表明：塔里木河流域出山径流水体以硅酸盐岩的碳酸化溶滤水为主，离子类型为HCO₃^--Ca²⁺型，其次为SO₄^2--（Ca²⁺+Mg²⁺）混合型.南缘昆仑山/帕米尔高原各子流域的出山径流中，TDS （溶解性总固体）和离子总量的加权平均值（权重为径流量）分别为424.02和356.20 mg/L，远高于北缘天山出山的相应值（268.43和220.04mg/L），这是因为天山山区分布大量的岩浆岩，抑制了区域水化学侵蚀强度.运用吉布斯图及因子分析等方法，确定出山径流的水质主要受硅酸盐岩的碳酸化作用控制，其中南缘昆仑山/帕米尔高原水系不仅伴有蒸发盐岩风化，还与天山阿克苏河水系一样，伴有碳酸盐岩风化.风化过程中，硫化物氧化产生的H⁺抑制了碳酸化风化，一定程度上限制了大气CO₂消耗，尤其是在有煤层、铜矿等硫化物分布的迪那河、喀拉玉儿滚河和喀什葛河流域.塔里木河流域出山径流中除了F^-和NO₃^-外，其他离子和总离子浓度均与冰川覆盖率和融水占径流比例之间存在良好的相关性.总离子浓度与冰川覆盖率之间建立的指数拟合方程，符合我国西北干旱区出山水质的特点，但受自然与人为因素的制约，与全球尺度拟合的方程存在一定差异.

Hydrochemical characteristics of the mountain runoff in Tarim River Basin,China

On the basis of regional geology, the reasons for the formation of hydrochemical components of the Mountain Runoff were analyzed, and the source of solutes and their controlling factors were discussed in Tarim River Basin, China. The results showed that the mountainous runoff was mainly composed of carbonated dissolving water of silicate rock with the dominant ion type of calcium bicarbonate (Ca-HCO₃) and the secondary type of calcium/magnesium sulfate (Ca/Mg-SO₄) mixture. The weighted averages of the total dissolved solids (TDS) and the total number of ions in the mountainous runoffs in the Kunlun Mountains and Pamirs Plateau were 424.02 and 356.20mg/L, respectively, which were much higher than the values of 268.43 and 220.04mg/L in the Tianshan Mountains, respectively. The differences were mainly due to that a large number of magmatic rocks spread over the Tianshan Mountains, which reduced the erosive intensity of regional hydrochemistry. With the combination of the methods of Gibbs diagram and factor analysis, it was determined that the water quality of mountain runoffs was mainly controlled by silicate weathering. The water system in the Kunlun Mountain and Pamirs Plateau was not only accompanied by evaporative salt rock weathering but also by carbonate rock weathering similar to that in the Aksu River system in Tianshan Mountains. During the weathering process, the H⁺ produced by sulfide oxidation inhibited the carbonation weathering, which lowered the atmospheric CO₂ consumption to a certain extent, especially in the Dina, Kara Yuergun and Kashgar River basins rich in coal seams and copper mines. With the exception of fluorine (F^-) and nitrate (NO₃^-), the concentrations of the other ions and the total ions all presented strong correlation with the rate of glacier coverage rate and the ratio of the glacial meltwater to surface runoff in the Tarim River basin. The fitted exponential equation established between the concentration of the total ion and the rate of glacier coverage conformed to the characteristics of mountain water quality in the arid area of northwest China. Nevertheless, under the interference of natural and anthropogenic processes, there existed a certain difference between the equations fitted in the Tarim River basin and on a global scale.