Effects of Chlamydomonas Reinhardtii proliferating, blooming and decaying on nitrogen release from sediment and the corresponding enzymatic mechanism under different temperature conditions

Water and sediment samples from Meiliang Bay in Lake Taihu, Eastern China, were employed to investigate the effects of Chlamydomonas Reinhardtii proliferating, blooming and decaying on nitrogen release from sediment and the corresponding enzymatic mechanism. The high temperature (35°C) was not only beneficial for algae proliferating and blooming but also accelerating algae decaying. In contrast, there were only low proliferation and decaying rates for the algae under the low temperature (15°C). Algae sedimentation was found to be simultaneous with their proliferating and suspending. Most of algae died and decayed during the sedimentation, and minority of them survived on the surface of sediment. In addition, the mount of NH₄⁺-N released from sediment got rise with algae proliferating, and the NH₄⁺-N concentrations in water increased with algae decaying. The algae proliferating obviously enhanced the activities of Nitrate reductase, Nitrite reductasea and Urease in sediment.