格尔木河中下游—达布逊湖段水化学变化特征研究

Character of Hydrochemistry in Golmud River-Dabsan Lake Water

1999年 8月对格尔木河—达布逊湖流域进行了系统考察 ,并对其地表水体取样分析后发现 ,河水水化学分布空间上从源头至湖中逐渐咸化 ,表现出明显的地貌分区性特征 ,且东河段水质异常咸化 ;时间上河水矿化度总体表现为逐年上升的趋势 ,湖水则相对稳定 .作为流域农牧业发展的水源地和近几年格尔木市移民建设的重点地区 ,其地表水体水化学的时空异常变化应引起足够的重视 .

In August, 1999, we investigated Golmud River-Dabsan Lake field and sampled systimatically from surface water along the river from the source-Kunlun Moutian to the end-Dabsan Lake. After that, we analysed the principal chemical composition of the river water and calculated some parameters such as mineralization, and types of hydrochemistry and so on. According to the fluctuation of mineralization along the river from south to north, five different regions may be distinguished: (1) region Ⅰ: gobi; (2) region Ⅱ; alluvial pluvial fan; (3) region Ⅲ: alluvial pluvial plain; (4) region Ⅳ: lacustrine plain; (5) region Ⅴ: brine lake, among which region Ⅱ can also be divided into two sub regions: (Ⅱ 1) the part of west river of alluvial pluvial fan and (Ⅱ 2) the part of the east river of alluvial pluvial fan. From region Ⅰ to region Ⅴ, the mineralization increased as a whole. There appears an abnormal high value in sub region Ⅱ 2, due to the disturbing as the shallow ground water has relatively higher salt content. The ground water level is so shallow as to reach the surface of earth, a great amount of salts were dissolved from soil by shallow phreatic water and then flowed into river, which made primitive fresh river water became half brine, the type of hydrochemistry changed suddenly from C Na Ⅱ to Cl Na Ⅲ. From this region toward the lake, the river discharge had no great change except for region Ⅲ. The hydrochemistry of region Ⅳ was nearly the same as in the region Ⅲ except that the mineralization was somewhat lower. As for region Ⅴ, the Dabsan Lake became a brine lake due to its long history of evolution. Origionally the region Ⅴ was a playa as a dissolution basin. Under the condition of extreme arid climate as well as high evaporation a brine lake came into being. Generally, the hydrochemistry of west river was more stable than that of the east river. The adjustment capacity of west river was better and does not easy to be disturbed by other water. In the long run, future harnessing of water resource should lay stress on the part of the west region, mean while some measures should be taken to keep the half brine water of east river from any further salilization.