[High-Frequency Dynamics of Water Quality and Phytoplankton Community in Inflowing River Mouth of Xin'anjiang Reservoir, China].

The tail of the reservoir is the unstable zone regarding water quality and phytoplankton community. Therefore, it is the crucial zone in aquatic ecosystem transitions. To understand the transition characteristics and driving mechanisms of water environment dynamics, high-frequency monitoring of the water environment and phytoplankton community in the tail of a deep and large reservoir, the Xin'anjiang Reservoir in southeast of China, was conducted using a water quality monitoring buoy and three-day interval water sampling during 18 months. Results show clear seasonal thermal and oxygen stratification in the river mouth of the reservoir. The nutrient and chlorophyll-a concentrations also show stratifying phenomena during the thermal stratification period. Heavy rain and inflow quickly consume the stratification. Nutrient concentrations were highly dynamic in the river mouth. The total phosphorus ranges from 0.011 mg·L-1 to 0.188 mg·L-1, and total nitrogen ranges from 0.75 mg·L-1 to 2.76 mg·L-1. Dissolved phosphorus comprised 56% of total phosphorus, and dissolved nitrogen occupied 88% of total nitrogen, respectively. Nutrient concentrations were influenced strongly by rainfall intensity and inflow rate. Total phosphorus and nitrogen concentrations were significantly related to the three-day accumulated rainfall. Nutrient concentrations in the flood season (March to June) were significantly higher than in the non-flood season (P<0.001). Seasonal phytoplankton proliferation also significantly influenced by total phosphorus concentration. The phytoplankton community changes significantly with seasons and flood events. Bacillariophytea was generally dominant throughout the year, with the predominant genus of Fragilaria spp., Cyclotella spp., Synedra spp., and Melosira spp. Cyanophyta biomass peaked in July, August, and September, with the dominant genus of Aphanizomenon spp., Microcystis spp., and Oscillatoria spp. Apart from the high temperature, storm inflow events also triggered Cyanophyta proliferation. The proliferation of Chlorophyta was similar to Cyanophyta, with the predominant genus of Pediastrum spp. and Closterium spp.. While the Cryptophyta biomass peaked during March to May, with the predominant genus of Cryptomonas spp.. Redundancy analysis shows that the influence factors of phytoplankton community dynamics include the inflow rate, temperature, water level, water transparency, total nitrogen, total phosphorus, and nitrogen to phosphorus ratio. The meteorological and hydrological factors were major factors for phytoplankton dynamics during later autumn and winter, while the nutrient will be the co-driving factors of phytoplankton community dynamics during summer and early autumn. The research confirmed the huge influence of the intensity rainfall event on the water environment in reservoirs and described the key environmental conditions for phytoplankton community dynamics. The research is useful for the design of the monitoring and forecasting system for water safety in drinking water source reservoirs.

[Study on propagation technology of Acanthopanax trifoliatus by cuttings].

OBJECTIVE: In order to obtain substantial clonal plants, we studied the cuttings propagation technology. METHODS: The cutting roots and stems of Acanthopanax trifoliatus were used as plant materials, and different materias, seasons and other conditions for cutting propagation were tested. RESULTS: It showed that the survival rate of stem segments was higher than that of root segments. The test of age of plant materials found that high survival rate could be obtained from semi-lignified stem segments and the segments from the base stem could survive successfully. Autumn was more suitable for plants' survival. Moreover, the rooting rate reached 89.4% by inserting segments with leaves into sand soil after dipping into 1500 mg/L IBA for 10 s, and with plastic membrane and shading net covered. CONCLUSION: The rooting rate can increase significantly by collecting semi-lignified basal stems in autumn, cutting them for leaf cuttings, and inserting them into sand soil after dipping into 1500 mg/L IBA for 10 s.

[Studies on purification of total saponins from the leaves of Acanthopanax trifoliatus by macroporous adsorption resin].

OBJECTIVE: To study the enrichment and purification of total saponins from the leaves of A. trifoliatus. METHODS: Using the total saponins from the leaves of A. trifoliantus as the standard index, we examinad the capability of static adsorption and desorption to select the optimum macroporous adsportion resin. Then we studied the purification technological parameters such as pH value, the dynamic adorption speed of flow, the best type quantity, the eluent density and so on. RESULTS: The optimum purification conditions were as follows: the type of macroporous adsorption resin was AB-8, the pH value of absorbing solution was 5-6, the absorbing velocity of flow was 1.0 mL/min, the concentration of ethanol as elutent was 70%, the proportion of the amount of absorbing solution and resins was 4:1, the proportion of the amount of elutent and resins was 4:1, the eluting velocity of flow was 2.0 mL/min.

[The contents changes of polysaccharides and total flavonoids during flower bud differentiation of Epimedium sagittatum].

OBJECTIVE: To study the dynamic changes of the contents of polysaccharides and total flavonoids Daring flower bud differentiation of Epimedium sagittatum. METHODS: The polysaccharides and total flavonoids from Epimedium sagittatum were extracted by Microwave-assisted method. The content of polysaccharides was determined by anthrone sulphuric acid colorimetry and that of total flavonoids was determined at 270 nm by ultraviolet spectrophotometry. RESULTS: The polysaccharides content in leaf decreased during the initial stages of floral bud differentiation and then increased, while the content in stem and fibrous root decreased steadily until floral bud differentiation completed. The content in rhizome kept invariant. In the flower bud physiological differentiation period,the content of total flavonoids in leaf and stem decreased and then kept invariant, while the content in rhizome increased and kept invariant. The content of total flavonoids in fibrous root increased during the initial stages of floral bud differentiation and then decreased. CONCLUSION: The contents of polysaccharide and total flavonoids have relation with the flower bud differentiation of Epimedium sagittatum.