Phytoplankton Species And Water Pollutuion Evaluation Of Xiangjiang River And Its Surrounding Water In Changsha

Xiangjiang River, the important water source for Changsha residents living and industry use, is the mother river of Hunan Province. Its hydrological regime change little in Changsha, self-purification ability is not strong, pollution significantly, susceptible to eutrophication. From2010May to2011September, the species investigation of planktonic algae was carried out, the result showed that there are50genera and73species (including varieties) of phytoplankton belonging to6phyla in all sampling sites, and Bacillariophyta has18genera and29species(40%), Chlorophyta has19genera and27species(37%), Cyanophyta has8genera and8species(11%), Euglenophyta has3genera and7species(10%), Xanthophyta and Dinophyta has1gengera and1species(1%,1%). There are43genera and61species of phytoplankton belonging to6phyla in Xiangjiang River of Changsha and35genera and50species of phytoplankton belonging to4phyla in Houhu Pond and16genera and23species of phytoplankton belonging to4phyla in Taozihu Pond. The dominant phyla in3waters are Bacillariophyta and Chlorophyta and Euglenophyta, and the dominant species are Melosira and Nitzschi and Cyclotella of Bacillariophyta, Chamydomonas and Pediastrun Meyen of Chlorophyta, Euglena of Euglenophyta, Microcystis and Oscillatoria of Cyanophyta. The growth tendency of algae is bloom in spring and grow fast in summer, the speed slightly down in autumn and winter. And Euglena and Chamydomonas bloom in autumn and winter.During the investigation, the physiacal and chemical indexes (including water temperature, dissolved oxygen, pH, transparency, total nitrogen and total phosphorus) was measured, the physicochemical index TN, TP content of Xiangjiang water in Changsha and its surrounding waters all reached rich nutrition critical value. The evaluation results shows that algae in Xiangjiang River is eutrophic (the Houhu and Taizihu is severe eutrophic) by used bioligical indicator; and the pollution level of Xiangjiang river is a-mesosaprobic zone and β-mesosaprobic zone by used saprobic system. In addition, a variety of algae which can tolerate organic pollution and heavy metals pollution had found in Xiangjiang, showed that Xiangjiang River was probably polluted by heavy metal cadmium, zinc and copper and organic pollutants. In river and its surrounding water the content of Melosira granulata, Melosira varians and Cyclotella eneghiniana of Euglenophyta, Chlamydomonas and Chlorella vulgaris of Chlorophyta, Oscillatoria and Microcystis of Cyanophyta is very rich, and the species of organic pollutants resisitant alage are rich. The Pearson product-moment correlation coefficient and Spearman’s rank correlation coefficient analysis was done, the sampling period of planktonic algae growth affected by nitrogen and phosphorus effect obviously, the planktonic algae in static water sampling points growth influenced by temperature obviously. The study of planktonic algae pollution indicator species and the pollution level shows that Xiangjiang River in Changsha is seriously polluted; environmental management work could not be ignored.This research combined biological indicator and physicochemical indexes to evaluate planktonic algae and water quality evaluation of the Xiangjiang River in Changsha section and its surrounding water. The result can provide certain theory basis for algae flora and quality monitoring and evaluation in research water, and provide management for the future environment comprehensive.