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The section of Jialing River flews through Chongqing City, it converges into the Yangtze river and receives heavy multi-source pollution of Chongqing urban city and water from upriver stream, serves as water supplying source and makes great influence on water quality downstream; after the three gorge project founded, Chongqing downstream belongs to lake type water, current velocity of the river is slow, the water receives heavy multi-source pollution of amount of waste water from the banks and the upstream water, and is a very important supplying water source. The water quality of this water area responses to water pollution of Chongqing upstream of the Three Gorge Reservoir, and affects the water environment and biology of the Three Gorge Reservoir. This article is on investigating and studying on two sections.One section is on investigating and studying on phytoplankton growth and dominant species of algae in the Chongqing reach of Jialing River; analyzing the factors that effects the composing, distributing and quantity of phytoplankton in this water area; and finding out algal character and seasonal variation under parameters effect, and making ecological evaluation of water quality.7 phyla, 50 genera and 88 species of phytoplankton community were identified in the Chongqing reach of Jialing River from April, 2006 to May, 2006. The proportion of the community compositionwas:Chlorophyta43.5%, Bacillariophyta 31.8%,Cyanophyta 12.9%, Euglenophyta 2.4%, Pyrrophyta and Chrysophyta1.2%. There was not single dominant species, Melosira sp., Cyclotella sp. of Bacillariophyta, Cymbella sp. of Chlorophyta, Cyanophyta was occurred as dominant species only in April. From April,2006 to January,2007, Bacillariophyta and Chlorophyta became dominant groups, the subdominant was Cyanophyta, Bacillariophyta became dominant groups in every season except for autumn, and in winter Bacillariophyta was significantly dominant groups, the abundance reached 4.69 ten thousand cells/L(87.27%), in autumn Chlorophyta and Bacillariophyta became dominant groups, the phytoplankton abundance respectively reached 2.803 ten thousand cells/L(43.99%), 2.765 ten thousands cells/L(43.40%). Above all the seasonal change curve of phytoplankton abundance was peak style, and the abundance reached highest value.Overall evaluation of the phytoplankton showed that, Chongqing reach of Jialing River has been in the rich nutritional level. Due to influence of hydrology and climate, the existing algae amount didn’t correspondingly make obvious response, and the water was subjected to heavy organic pollution, it indicated that water pollution in summer and winter was more serious than in other seasons.The other section is on investigating and studying on phytoplankton growth and dominant species of algae in the Chongqing downstream of the Three Gorge Reservoir ; analyzing the factors that effects the composing, distributing and quantity of phytoplankton in this water area; and finding out algal character and seasonal variation under parameters effect, and making ecological evaluation of water quality.4 phyla, 11 genera and 11 species of phytoplankton community were identified in the Chongqing reach of Jialing River from March 23th, 2007 to March 27th, 2007. The proportion of the community composition was: Bcillariophyta 45.45%, Chlorophyta 36.36%, Pyrrophyta and Euglenophyta 9.09%. Melosira sp., were occurred at every sampling site. The algal abundance from upstream to downstream of mainstream of the Three Gorge Reservoir was separately 1.49×10~4cells/L, 2.59×10~4cells/L, 0.645×10~4cells/ L, 0.815×10~4cells/L. The algal abundance from upstream to downstream of branch of the Three Gorge Reservoir was separately 3.52×10~4cells/L, 3.00×10~4cells/L, 3.01×10~4cells/L, 0.08cells/L.According to correlation analysis, there were no significant correlation between the phytoplankton abundance and chlorophyll a. The phytoplankton abundance of mainstream of the Three Gorge Reservoir was correlate with water quality factor, but there was some significant correlation between the phytoplankton abundance of branch of the Three Gorge Reservoir and water quality factor. Overall evaluation of the phytoplankton showed that, the water quality pollution of mainstream and branch of the Three Gorge Reservoir were both serious, and the water quality pollution in the branch of the Three Gorge was more serious, and it maybe occur water bloom in the branch.
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