青海湖湖水蒸发实验研究

青海湖位于青藏高原的东北部 ,是一个典型的大陆微咸水湖。其湖水盐度为 1 4 0 7g/L ,水化学类型为硫酸钠亚型 ,化学组成不同于海水。该湖水为CaCO3所饱和 ,正在析出文石。为了揭示其湖水演化的趋势、析盐顺序和各种盐类形成的条件 ,曾在湖的南岸采集了大量湖水进行了蒸发实验和冷冻—蒸发实验。蒸发实验的结果表明 :首先析出水菱镁矿 ,随着湖水继续浓缩进一步析出石盐、无水芒硝、白钠镁矾、软钾镁矾、泻利盐、钾石盐和光卤石。冷冻—蒸发实验的结果是 :首先析出水菱镁矿 ,然后是芒硝、三水菱镁矿、石盐、泻利盐、光卤石和水氯镁石。这些实验的最终母液在室内保存了 1— 2月 ,均析出了硼酸盐。上述实验的析盐顺序和结晶途径与海水明显不同 ,而与某些青藏高原盐湖和我国东部某些第三纪古湖盆相似 ,如柴达木盆地的大浪滩干盐湖和山东的大汶口盆地等。因此 ,这些实验结果对于阐明青海湖湖水的演化趋势、青藏高原盐湖的形成和演化、以及大陆湖盆钾盐和其它盐类矿产资源的形成都是非常重要的

An Investigation on Evaporating Experiments for Qinghai Lake Water,China

Qinghai Lake is located in the northeastern part of Qinghai-Xizang(Tibet) Plateau,and it is a typical continental brackish-water lake. The lake water belongs to sodium sulphate subtype with a salinity of 14 07 g/l , and obviously differs from seawater in chemical composition. It is saturated by CaCO 3 and aragonite is separating out. In order to reveal the evolving tendency of the lake water, salt-separating sequences and forming conditions of various salt deposits, we took a large amount of lake-water near the southern bank of the lake and carried out the evaporating and freezing-evaporating experiments. The evaporating experimental results show that, hydromagnesite is first separated with the lake-water being concentrated, and then halite, thenardite, bloedite, picromerite, epsomite, sylvite and carnallite precipitated successively. The results of freezing evaporation show that, first hydromagnesite, and then mirabilite, nesquchonite, halite, epsomite, carnallite and bischofite separated, respectively. The final mother liquid of those experiments were preserved for 1-2 months(in laboratory) and borates were precipitated. The above salt-separating sequence and crystallization pathway obviously differ from those of seawater, and are similar to some saline lakes on Qinghai-Xizang(Tibet)Plateau and some ancient lake basins of Tertiary in the eastern China, such as Dalongtan Playa(Qaidam Basin)and Dawenkou Basin(Shandong province) etc.. Therefore, these experimental results are very important for illustrating the evolving tendency of the Qinghai-Lake water and the formation and evolution of the salt lakes of Qinghai-Xizang (Tibet) Plateau, as well as the formation of potash deposits and other salt resources in continental lake basins.