Abstract
To reveal the biochemical mechanism of decomposition and synthesis of the nutrients in eutrophic lakes,the relationships among the contents of nitrogen,phosphorus,organic matter and ammonium nitrogen,the activity of hydrolase and oxidoreductase,and the amounts of different microorganisms were studied in six shallow lakes along the Yangtze River.The results showed that 1) in the lakes seriously polluted by farming activities,such as the Datong Lake,Shanpo Lake and Saicheng Lake,the urease activity in sediments was significantly higher than that in the lightly polluted large lakes,such as the Poyang Lake and Dongting Lake.And it showed significantly positive correlation with total nitrgen(TN) and orgnic matter(OM) in sediments(r=885,P0.01;r=0.900,P0.01,respectively).And alkaline phosphatase also showed a positive correlation with total phosphorus(TP)(r=0.986,P0.01);2) the changing trends of the activities of catalase,polyphenol oxidase and peroxidase were similar in lake sediments.And their distribution had a close relation with the degree of pollution and human activities;3) among the microoganisms in lake sediments,bacteria were dominant,actinomycetes were next and fungi were the least.There was little discrepancy of the number of ammonium bacteria in all the lakes,while the number of denitrifying bacteria was quite different.So,denitrifying bacteria might be an important bio-indicator factor which could reflect whether nitrogen accumulated or not in the lake sediments,and also reflect the degree of eutrophication.
Published Version
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