Journal of Geographical Sciences ›› 2015, Vol. 25 ›› Issue (6): 687-700.doi: 10.1007/s11442-015-1196-5

• Orginal Article • Previous Articles     Next Articles

Spatial-temporal patterns of major ion chemistry and its controlling factors in the Manasarovar Basin, Tibet

Zhijun YAO1(), Rui WANG1,2,*(), Zhaofei LIU1, Shanshan WU1, Liguang JIANG1   

  1. 1. Institute of Geographic Sciences and Natural Resources Research, CAS, Beijing 100101, China
    2. University of Chinese Academy of Sciences, Beijing 100049, China
  • Received:2014-11-17 Accepted:2015-01-22 Online:2015-06-15 Published:2015-06-15
  • Contact: Rui WANG E-mail:yaozj@igsnrr.ac.cn;wangr.12b@igsnrr.ac.cn
  • About author:

    Author: Yao Zhijun (1959-), Professor, specialized in hydrology and water resources studies. E-mail:yaozj@igsnrr.ac.cn

  • Supported by:
    National Natural Science Foundation of China, No.41190080;“Strategic Priority Research Program (B)” of the Chinese Academy of Sciences, No.XDB03030400

Abstract:

The Manasarovar Basin in southern Tibet, which is considered a holy land in Buddhism, has drawn international academic attention because of its unique geographical environment. In this study, based on actual measurements of major ion concentrations in 43 water samples collected during the years 2005 and 2012, we analyzed systemically the spatial- temporal patterns of water chemistry and its controlling factors in the lake and inflowing rivers. The results reveal that the water in the Manasarovar Basin is slightly alkaline, with a pH ranging between 7.4-7.9. The amounts of total dissolved solids (TDS) in lake and river waters are approximately 325.4 and 88.7 mg/l, respectively, lower than that in most of the surface waters in the Tibetan Plateau. Because of the long-term effect of evaporative crystallization, in the lake, Na+ and HCO3- have the highest concentrations, accounting for 46.8% and 86.8% of the total cation and anion content. However, in the inflowing rivers, the dominant ions are Ca2+ and HCO3-, accounting for 59.6% and 75.4% of the total cation and anion content. The water exchange is insufficient for such a large lake, resulting in a remarkable spatial variation of ion composition. There are several large inflowing rivers on the north side of the lake, in which the ion concentrations are significantly higher than that on the other side of the lake, with a TDS of 468.9 and 254.9 mg/l, respectively. Under the influence of complicated surroundings, the spatial variations in water chemistry are even more significant in the rivers, with upstreams exhibiting a higher ionic content. The molar ratio between (Ca2++Mg2+) and (Na++K+) is much higher than 1.0, revealing that the main source of ions in the waters is carbonate weathering. Although natural processes, such as rock weathering, are the major factors controlling main ion chemistry in the basin, in the future we need to pay more attention to the anthropogenic influence.

Key words: Manasarovar, surface water chemistry, spatial-temporal distribution, rock weathering, Tibetan Plateau