[Succession of Phytoplankton Assemblages and Its Influencing Factors in Tangpu Reservoir, Zhejiang Province].

In order to explore the spatial-temporal dynamics of phytoplankton assemblages and its influencing factors in Tangpu Reservoir, phytoplankton and environmental variables were monthly monitored in 2011. The results showed that a total of 115 species of phytoplankton were identified, which belonged to 7 phyla and 62 genera. Phytoplankton abundance varied monthly with the maximum value (20.88×106 cells·L-1) in April and minimum (0.59×106 cells·L-1) in June. Variation partitioning of species data matrix showed that the variation of phytoplankton communities among months (account for 72.3%) was much larger than that among sampling sites (account for 2.5%), which indicated that phytoplankton communities had a high temporal but low spatial heterogeneity. Dominant species showed a marked seasonal succession pattern: diatom and blue-green algae species in spring, blue-green algae and green algae species in summer, diatom and cryptomonads species in autumn and winter. Result of multivariate analysis (RDA) indicated that HRT was the key factor affecting the shift between hydrological disturbance sensitive and tolerant species, and the formation of spring algal bloom; SiO2, WT and N:P were the key factors affecting the shift from diatom and cryptomonads species to blue-green algae and green algae species.

[Study on efficiency of nitrogen and phosphorus removal by algal biofilm].

Cultivating algal biofilm on nitrogen (N) and phosphorus (P) in waters presents an alternative to control eutrophication. Under laboratory conditions, efficiency on nitrogen and phosphorus removal from synthetic wastewater, secondary effluent and eutrophic lake water by algal biofilm was assessed. Algal biofilm was mainly composed of blue-green algal species Oscillatoria princeps. During a 5-day treatment, for synthetic wastewater, secondary effluent and eutrophic lake water, removal rates of TN were 57.1%, 94.5% and 93.8%, respectively, removal rates of TP were 93%, 73% and 79%, respectively. The dried algal production were 3.7 - 7.2 g x m(-2)x d(-1), and the TKN and TP of algal biomass were 5.7% - 7.2% and 0.78% - 2.44%, respectively. Recovery of nutrients in harvested algal biomass accounted for about 20% - 39% for N and 65% - 82% for P.