[Succession Characteristics and Water Quality Responsiveness Evaluation of FG and MBFG in Yanlong Lake Water Source Ecological Purification System].

ABSTRACT

To explore the water purification efficiency and phytoplankton control efficiency of the water source ecological purification system, and evaluate the effectiveness of the functional group (FG) and morphology-based functional group (MBFG) in response to the internal environment and water quality of the water source ecological purification system, in the summer of 2018, the water quality and phytoplankton functional groups of each unit of the Yanlong Lake ecological purification system were monitored and analyzed. The results showed that the Yanlong Lake water source ecological purification system can effectively purify the water. The average values of total phosphorus, total nitrogen, dissolved oxygen, and turbidity in the influent water were 0.20 mg·L-1, 1.91 mg·L-1, 2.88 mg·L-1, and 60.23 NTU, respectively; after system treatment, these were 0.09 mg·L-1, 0.95 mg·L-1, 6.26 mg·L-1, and 39.53 NTU, respectively. Simultaneously, the spatial distribution of water quality within the system was heterogeneous, with significant spatial differences in dissolved oxygen (DO), pH, and turbidity (P<0.001). The Yanlong Lake water source ecological purification system could effectively control the density of phytoplankton (4.42×105-4.32×106 cells·L-1) when the effluent was in a mild eutrophication state. This reduced the risk of algal blooms. There were five absolute advantage FGB, P, TC, J, and W1. There were six absolute advantage MBFGGroupⅠ, GroupⅢ, GroupⅣ, GroupⅤ, GroupⅥ, and GroupⅦ. Both absolute dominant functional groups were effective in indicating changes in habitat conditions. The results of RDA analysis found that the environmental interpretation of the MBFG was higher than that of the FG. The results suggested that it is more appropriate to study the dynamics of phytoplankton in the Yanlong Lake ecological purification system in summer by selecting the MBFG classification method.