Water Quality and Phytoplankton Index Evaluation in a Heavily Polluted Urban River Connected With Yangtze River in Zhengjiang

In the spring of 2011( April 23),water quality and phytoplankton were investigated in 12 field sampling sites in the ancient Canal,an urban river connected with Yangtse River in Zhenjiang. The results of water quality evaluation showed that this river was heavily polluted under eutrophic condition,and deteriorated along the river. There were 5 phyla including 71 species of phytoplankton were identified in this investigation,with the abundance ranged from 0. 4 × 106 to 106. 8 × 106cells /L,biomass from1. 72 to 54. 65 mg /L. Chlorophyta and Cyanophyta were the predominant phyla,and the dominant species were all resistance to pollution. In different sampling sites along the river,there was great difference in the community structure indices including density,composition ratios of species,and diversity. The results of water quality evaluation by different phytoplankton indices were different.In the heavily polluted and eutrophic urban rivers,phytoplankton biotic survey for water quality evaluation should be carried out by a comprehensive index.