Laboratory of Applied Environmental Chemistry, University of Kuopio, Patteristonkatu 1, FIN-50100 Mikkeli, Finland.
Sci Total Environ. 2009 Dec 1;407(24):6242-54. doi: 10.1016/j.scitotenv.2009.09.001. Epub 2009 Sep 23.
The Tibetan Plateau covers an area of about one fourth of Europe, has an average elevation over 4000m above sea level, and is the water sources for about 40% of world's population. In order to foresee future changes in water quality, it is important to understand what pressures are governing the spatial variation in water chemistry. In this paper the chemistry including major ions and trace elements in the headwaters of four major Asian rivers (i.e. the Salween, Mekong, Yangtze River and Yarlung Tsangpo) in the Tibetan Plateau was studied. The results showed that the content of dissolved salts in these Tibetan rivers was relatively high compared to waters from other parts of the world. The chemical composition of the four rivers were rather similar, with Ca(2+) and HCO(3)(-) being the dominating ions. The exception was the Yangtze River on the Plateau, which was enriched in Na(+), Cl(-), SO(4)(2-) and Li due to silicate weathering followed by strong evaporation caused by a negative water balance, dissolution of evaporites in the catchment and some drainage from saline lakes. The concentrations of heavy metals (Cu, Co, Cr, Ni, Cd, Pb, and Hg) and As, NH(4)(+) were generally low in all the rivers. Anthropogenic impacts on the quality of the rivers were identified at a few locations in the Mekong River and Yarlung Tsangpo basins. Generally, the main spatial variation in chemical compositions of these under studied rivers was found to be governed mainly by difference in geological variation and regional climatic-environment. Climate change is, therefore, one of main determining factors on the water chemical characteristics of these headwaters of Asian major rivers in the Tibetan Plateau.
青藏高原面积约占欧洲的四分之一，平均海拔超过 4000 米，是世界上约 40%人口的水源地。为了预测未来水质的变化，了解控制水质化学空间变化的压力因素非常重要。本文研究了青藏高原四条亚洲主要河流（即萨尔温江、湄公河、长江和雅鲁藏布江）源头的主要离子和微量元素化学。结果表明，与世界其他地区的水相比，这些西藏河流的溶解盐含量相对较高。四条河流的化学成分非常相似，Ca(2+)和 HCO(3)(-)为主要离子。雅鲁藏布江是个例外，由于硅酸盐风化和负水量平衡导致的强烈蒸发，以及流域内蒸发盐的溶解和一些来自盐湖的排水，使该河流富含 Na(+)、Cl(-)、SO(4)(2-)和 Li。重金属（Cu、Co、Cr、Ni、Cd、Pb 和 Hg）和 As、NH(4)(+)的浓度在所有河流中普遍较低。在湄公河和雅鲁藏布江流域的一些地方发现了人类活动对河流水质的影响。一般来说，这些研究河流的化学成分的主要空间变化主要受地质差异和区域气候环境的控制。因此，气候变化是青藏高原亚洲主要河流源头水化学特征的主要决定因素之一。
