Distributions Of Activities Of Several Oxidoreductases In Sediments Of Shallow Lakes And Their Ecological Significance

The enrichment of organic matter is a striking feature of lake entrophication. However, the studies on degradation of organic matter mediated by extracellular enzymes in sediments are inadequate. In this dissertation, the role played by oxidoreductases in degradation process of organic matter in sediments and their effects on eutrophication are discussed from two respects:1) Field investigationsThe spatial and temporal distributions of activities of several oxidoreductases (polyphenol oxidase, peroxidase and catalase) and their correlations with microorganisms in sediments of shallow lakes were briefly described. The study lakes localized in the middle and lower reaches of the Yangtze River, including Lake Luhu, Lake Liangzi, Lake Houguan, Lake Niushan, Lake Sanjiao, Lake Longyang, Lake Moshui, Lake Yuehu, Lake Dalianhua, Lake Xiaolianhua in Hubei province and Lake Taihu in Jiangsu Province. Spatially, the lake sediments with significantly higher contents of organic matter showed higher activities of oxidoreductases, and the activities within the lakes were also unevenly distributed. The higher values were observed in the inlet of waste water discharge, the zone with plant residues and the undredged sites; Vertically, high activity of polyphenol oxidase was shown in surface sediment with higher organic matter. Hence, the organic matters derived from the different sources could induce enzyme, but it had little effect on catalase activity. Activity of peroxidase varied little with increasing depth of sediments and was similar in the dredged and undredged sites, which was probably due to the formation of...