Study On The Eutrophycation Of The Characteric Water Body In Chongqing Urban City In Situ

When the water level of the Three Gorges Reservoir moved up to 175 meter, the backwater area of ChangJiang River will be to HuaHongbao, JiangJing, and that of Jia Ling River will be to HeChuan. Then all the water body in the ChongQing urban city will be affacted by the Three Gorges Reservoir. "Water bloom" have being founded in mang trbutaries of ChangJiang River till the water level of the the Three Gorges Reservoir moved up to 135m. So, the water quality condition of Chongqing urban city calls our attentions when the water level moves up to 175m.Lots of reseachers have been paying mang attentions to the eutrophycation of the Three Gorges Reservoir, but, so far, there is not a theory or experience method for forcating the "water bloom" in the large reservoir as The Three Gorges Reservoir. This paper selected the characteristic water body of ChongQing urban city as objects.Based on the data between March and December in 2009, we anslyse the spatio-temporal changing of the phytoplankton community and phytoplankton cell density,study the correlations between phytoplankton cell density and velocity, water temperature,water transparency, permanganate index,TN, TP. We evaluated the water quality codiiton based on the biological diversity, TLI and alga cell density.5 phyla,49genus and 109 species of phytoplankton were identified in the water of Chongqing urban city between March ang December,2009. Of them 24 genus,69 species are founded in Bacillariophyta; 18genus,31species in Chlorophyta; 4 genus,4 species in Cyanophyta; 2 genus,3 species in Euglenophyta;1 genus,2 species in Pyrrhophyta. Time variation of species is singnificant.There is only Bacillariophyta between July and September. Shannon-Wiener, Margalef and Pieluo indexes show that the compleity of the phytoplankton community and the evenness of the ohytoplankton species are poor.and the abundant of phytoplankton community is ok in the water body of Chongqing urban city.Between March and December,2009,the phytoplankton cell density fluctuate between 0～6.03x105cell/L,it lower than Cyanophyta cell controlling level of 9.1x105cell/L in drinking water source suggested by Publice Health School of FuDan univercity. This suggests that the water quality belong to middle eutrophicatin and it can meet the drinking water source standard, considing of phytoplankton cell density.Temporal variation of phytoplankton cell density in each section is significant, that is phytoplankton cell density in March to May>Jun to September>Octomber to December.The post hoc tests results(S-N-K) show that the phytoplankton cell density difference between March to May and Jun to September is singnificant, so is the cell density between March to may and Octomber to December. And the difference of phytoplankton(Chlorophyta, Cyanophyta, Euglenophyta, Pyrrhophyta) cell density between Jun to September is not significant and that of Octomber to December. As to the spatial variation, the phytoplankton cell density in Daxigou is higher than that in other sections. The celll density difference is not singnifiacnt one another among sections. There is no significant difference between Bacillariophyt and Euglenophyta cell densities on the sampling sites in each section. The difference of Pyrrophyta, Chlorophyta, and Cyanophyta cell density is singnificant on different sampling sites in each section.The phytoplankton of chongqing urban city water body is changing from rivertype Bacillariophyta to laketype Chlorophyta and Cyanophyta.The results suggest that the growth of phytoplankton is controled by water temperature,in Daxigou. Water velocity,light intensity and the water transperance index are the controling factors of the phytoplankton growth in Fengshouba,Chaotianmen and Tangjaituo. The correlations between Cyanophyta cell density and the velocity,water temperature are negative.The water velocity will become slower and water transparency will be bigger than usual of water body in ChongQing urban city when the weter level of the Three Gorges Reservoir moved up to 175 m in winter.And the nutriant salts concentrations in the water are higer than the eutrophication standard. We should take note of the grow of Cyanophyta in the water body of ChongQing urban city.