[Distribution features of nutrient and phytoplankton in incipient Three Gorges reservoir]

The distribution features of nutrient and chlorophyll a were determined by cruise during 2003-09-08 approximately 2003-09-15 with 11 sites in the Three Gorges reservoir. The results showed that the concentration of nitrogen was exceed the national surface water body quality standard III. The concentration of nitrogen range 1.01 approximately 1.35 mg x L(-1); Total phosphorus range 0.028 approximately 0.054 mg x L(-1); Kalium range 2.80 approximately 3.44 mg x L(-1); Total organic carbon range 1.92 approximately 2.59 mg x L(-1); Chlorophyll a range 1.58 approximately 7.53 mg x m(-3). The average concentration of chlorophyll a was 4.69 mg x m(-3) at surface layer. The correlation of nutrient and chlorophyll a were researched. It indicated there was a significant positive correlation (r = 0.7287) between chlorophyll a and NO3(-)-N. There was a significant negative correlation (r = -0.9207) between chlorophyll a and turbidity. Using the method of system cluster, it showed there was distinct distribution features which can be divided into three clusters. The upper river areas cluster included Changshou, Fuling,Fengdu, Zhongxian; The middle river areas cluster included Wanzhou, Yunyang and Fengjie; The down river areas included Wushan. The rate of diatom in phytoplankton was about 86%. Diatom was absolute predominance on 4 monitoring sites. The average of diatom was 129844 cells x L(-1). Amount of phytoplankton was increased along the river flow direction.