Effects Of Chlamydomonas Reinhardtii Proliferation, Sedimentation And Decay On The Concentrations Of Inorganic Nitrogen From Sediment

Water eutrophication is a serious environmental problem in the world. There are numerous lakes and rivers that have been polluted in different levels in China. Taihu lake in China is one of the key administration eutrophication Shallow lakes. Currently, external pollutant sources got certain degree of control but releases of nutritive salt from sediment have always stimulated entrophication in Lake Taihu. As an important parameter that affects the release processes of nutrition salt from sediment, algae itself and various environmental parameters take actions together. Water and sediment samples from Meiliang Bay in Lake Taihu, Eastern China, were employed to investigate the effects of Chlamydomonas Reinhardtii proliferation, sedimentation and decay on nitrogen release processes from sediment under incubation conditions.Through studying utilization preference of Chlamydomonas Reinhardtii on inorganic nitrogen, the results showed that algae proliferation consumed NO3--N, NH4+-N. But NO3--N in the system more tended to been utilized by algae than NH4+-N. Moreover, the culture system with the dominant NO3--N was beneficial to enhance algae proliferation. This would be significant to further study effects of Chlamydomonas Reinhardtii proliferation and sedimentation on changes of nitrogen from water and sediment.Through studying effects of Chlamydomonas Reinhardtii proliferation and sedimentation on nitrogen concentrations in water and sediment, the results showed high temperature (35℃) was not only beneficial for algae proliferation and sedimentation but also accelerating algae decay. In contrast, there were only low proliferation and decay rates of algae under the low temperature condition (15℃) Algae sedimentation was found to be simultaneous with their proliferation 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 proliferation, and the NH4+-N concentrations in water increased with algae decay. The algae proliferation obviously enhanced the activities of nitrate reductase, nitrite reductase and urease in sediment, which maybe accelerate NO3--N being transformed into the gaseous N rather than NH4+-N.Effects of Chlamydomonas Reinhardtii proliferation, sedimentation and decay on dynamic processes of nitrogen in water were studied under exclusive sediment condition. The results showed that NO3--N, NO2--N and NH4+-N in the system were all consumed by algae. And the release of NH4+-N from water was enhanced in the process of algae decay.