The hydrochemistry of river water is closely related to the physical and geographical conditions in a basin, and the characteristics of river hydrochemistry are determined by the geological and environment factors in the basin. The rock weathering type and chemical weathering process can be deduced by studies on the hydrochemistry of rivers. Based on the collected hydro-chemical data of eight major cross-border rivers in China(Yarlung Zangbo River, Nujiang River, Lancang River, Ili River, Ertix River, Heilongjiang River, Red River and Shiquan River), this paper makes a comparative study on the hydro-chemical characteristics of major trans-boundary rivers in China using Gibbs diagram, triangle diagram, nonparametric test and principal component analysis. We make a comparative study on the main controlling factors and sources of dissolved substances in these trans-boundary rivers under different climatic biome and lithological conditions, so as to provide scientific basis for subsequent rock weathering and CO2 consumption as a geological carbon sink. It also provides a scientific basis for China to take the initiative in cooperation of trans-boundary river basins. The results show that the range of river pH is 7.60 ±0.93~8.29 ±0.14, which is weakly alkaline. The range of total dissolved solids(TDS) is 139.14 ±106.58~238.03 ±85.47mg/L, higher than the average of world rivers(100mg/L). Regarding the chemical composition of river waters, the cations are mainly dominated by Ca2+, the anions are mainly HCO3-, and the hydro-chemical type is HCO3--Ca2+ type. The non-parametric test shows that there are significant differences in the major ions among rivers. In addition, the concentrations of Ca2+ and HCO3- are higher in the rivers with carbonate rocks mainly distributed in catchment. The hydro-chemical composition of river water is controlled by rock weathering, which is promoted or weakened by rainfall and runoff. Therefore, catchment lithology is the first influencing factor, and climate is the second influencing factor. The ions in river water are mainly controlled by the chemical weathering of carbonate rocks with the participation of carbonic acid and sulfuric acid. The main ions of the Ertix River and Red River mainly come from the participation of carbonic acid in the chemical weathering process of carbonate rocks. The main sources of hydro-chemical ions in the Yarlung Zangbo, Nujiang and Heilongjiang Rivers are sulfuric acid and carbonic acid participating in the chemical weathering process of carbonate rocks. The hydrochemistry of the Shiquan River mainly comes from sulfuric acid and carbonate acid with a molar ratio of 1︰1 to participate in the weathering process of carbonate rocks, while the hydrochemistry of the Lancang River and Ili River mainly comes from sulfuric acid participating in the chemical weathering process of carbonate rocks. In general, the weathering of carbonate rocks is dominated by calcite. In the process of chemical weathering of carbonate rocks in the Nujiang River and Ili River basins, dolomite and calcite participate in the molar ratio of 1︰1. The water chemistry of the Yarlung Zangbo River, Lancang River, Yili River, Heilongjiang River and Shiquan River are also affected by human activities. The concentrations of trans-boundary-river major ions do not exceed the standard of drinking water in China and the recommended standard of the World Health Organization.

利用Gibbs图、三角图、非参数检验、主成分分析等方法对比研究中国主要跨境河流(雅鲁藏布江、怒江、澜沧江、伊犁河、额尔齐斯河、黑龙江、红河和狮泉河)的水化学特征, 探讨不同气候、岩性等条件下跨境河流河水中溶解性物质的主控因素及来源。结果表明: 河流pH范围为7.60±0.93~8.29±0.14, 呈弱碱性; 总溶解性固体(TDS)范围为139.14±106.58~238.03±85.47mg/L, 均高于世界河流平均值(100mg/L), 为弱矿化度水; 河水水化学组成中阳离子以Ca2+为主, 阴离子以HCO3-为主, 水化学类型为HCO3--Ca2+型。主要离子在河流间存在显著性差异, 对河流水化学而言, 岩性为第一级影响因子; 河水离子主要受碳酸与硫酸参与的碳酸盐矿物化学风化作用控制, 总体上, 碳酸盐岩以方解石的风化作用为主; 雅鲁藏布江、澜沧江、伊犁河、黑龙江和狮泉河水化学还受到人为活动影响; 主要离子浓度未超过中国生活饮用水标准及世界卫生组织推荐标准。本研究为后续跨境流域岩石化学风化引起的大气CO2消耗这一地质碳汇提供依据。