Abstract: According to water chemistry data from 1959 to 1984 at 109 monitoring stations collected from the water yearbook edited by the Water Conservancy Ministry of China, the chemical characteristics and genesis of major ions of the Pearl River System were investigated. The results are as follows. The contents of total dissolved solids in the Dongjiang River are relatively low (about 66.1mg/L) and the hydro-chemical type is C^Na. The contents of total dissolved solids in the Xijiang River are relatively high (about 202.5mg/L) and the hydro-chemical type is C^Ca, and those of the Beijiang River are between these of Dongjiang and Xijiang. The ionic runoff modules in pearl River Basin are much higher than those in the other river basin of China. The composition of major ions in the Dongjiang is dominated by the weathering of alumno-silicates stones and the ionic composition in the Xijiang is dominated by the leaching of limestones.

Key words: Chinese river, Pearl River, water chemistry, ionic runoff modulus

摘要： 对珠江水系109个水文站1954—1984年的水化学资料的研究表明，在组成珠江水系的3条河流中，以东江离子总量为最低，西江的离子总量为最高，前者的化学类型为重碳酸盐钠型水,后者为重碳酸盐钙型水。北江的离子总量和水化学类型介于上二者之间。珠江水系的离子径流模数远高于我国河流平均离子径流模数。在3条河流中，以北江的离子径流模数为最高，东江为最低，西江介于上二者之间。其原因与3条江流域的面积、岩石类型和降水量有关。西江和北江水中的离子主要起源于岩石风化，东江水中的离子有部分来自海洋气溶胶的补给。

关键词: 中国河流, 珠江, 水化学, 离子径流模数