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Limiting factors of planktonic algae’ growth in gufu river of three gorges reservoir region, A near-natural river of central China

Jiwen Ge, Jinpu Gu, Jia Tang, Shuyuan Wu, Guihua Ran, Lu Zeng

From August 2010 to December 2010 and February 2011 to August 2011(A total of 12 months), we choose 13 sampling points in Gufu River basin which have little human disturbance and rich geological origin phosphorus, to have environmental gradient sampling using field, continuous ways. 156 planktonic algae water samples were collected altogether and more than 2000 valid data were obtained. The data shows that the algae in Gufu River flowing water area are in their growth period, but influenced by restrictive factors, the growth is in deceleration phase; Through correlation analysis, we know that the total nitrogen, nitrate nitrogen and chlorophyll a have significant negative correlation, ammonia nitrogen, dissolved oxygen and chlorophyll a have significant negative correlation, while total phosphorus, water flow rate, pH and chlorophyll a have little correlation between them. The ratio of total nitrogen and total phosphorus in water is 7.06 : 1, The growth of algae reduces the concentration of total nitrogen, but it is also limited by it, their relationship is: y=0.001203-0.000475x, R2=0.692, P=0.00042 (y stands for the concentration of chlorophyll a, x stands for total nitrogen concentration). In terms of nutritive salt, the relationship between environmental restrictive factors and planktonic algae growth is not so obvious.