Dynamics of nitrogen with the development of C. Reinhardtii under a simulated water-sediment condition

Water and sediment samples, collected from Meiliang Bay in Taihu Lake, were employed to investigate the dynamics of nitrogen during the courses of proliferating, suspending and decomposing of C. Reinhardtii under a simulated water-sediment condition. Results showed that the total nitrogen concentrations in water increased 20% as compared to the control during the sedimentation and decomposition of algae. This indicated that the decay of algae cells, particularly during the late period of water blooms, would release plenty of nitrogen, which should be paid more attentions for a eutrophic lake. In addition, the activities of nitrate reductase and urease kept a high level during the proliferation of algae, and then they dropped gradually. The observation implied that algae blooms contributed to some content to the release of NH₄⁺-N from sediment.