关键词: 化学地理特征, 河流, 中国东部

Abstract: In the eastern part of China,the average pH in the river water mainly-connected with bicarbonate,is 6.7-3.1,Due to different contents of total salt,the river water is divided into 4 regions; 1.In the lowest-content legion,the total salt is<100mg/l; 2.In the second lowest-content region,the total salt is 100-200mg/l; 3,In the middle-level content region,the total salt is 200-500mg/l; 4,In the high content region,a very small area,the total salt is 500-1000mg/l.Most of the river waters are soft water with the hardness<8(German),but the water hardness in the Yellow River and in the Hai River is as high as 8-16.Due to different contents of COD,the river water is divided into 3 regions:1.At the northern part of Northeast China,COD content in rivers is rather high; COD≥1img/1,2.From the southern part of Northeast China to the Yantze River,which is a transitional area,COD content in rivers is 2-1mg/1.3.To the south of the Yantze River,COD content is comparatively low.COD≤1-2mg/l.Moreover the alkali capacity is rather low in most river water,i.e.<1.0m.e/l; while the acid capacity is rather high,i,e>1.0m,e/l.And in the eastern part of China,most river water is dissolution-erosional.

Key words: geochemical characteristics, river system, East China