Effects Of Zn,Fe,Mn On The Cell Multiplication Of Phytoplankton In Fresh Water

The Miyun Reservoir, the most important source of the surface water and the only source of drinking water in Beijing , has a tend of getting worse and the main problem were the entrophication of water body and the propagation of phytoplankton. Among them cyanobaterica, chlorophyta and bacillariophyta were predominant. TN &TP were the two macroelements which influenced the growth of phytoplankton in the Reservoir. The microelements such as Zn²⁺% Fe³⁺ & Mn²⁺ were the essential elements for phytoplankton. Based on a lot of investigations at spot about effects of microelement such as Zn²⁺, Fe³⁺& Mn²⁺ on algal growth propagation (AGP) was done at the lab and also discussed the role of the elements of Zn²⁺, Fe³⁺ & Mn²⁺ in algae propagation.The data of AGP experiment indicated that the ranges of Zn²⁺ optimal concentrations for Microcystis aeruginosa, Scenedesmus obiquus and Fragilaria.sp were 0.02～1μg/L, 0.1～100μg/L, 0.02μg/L, and the ranges of Fe³⁺ concentrations were 0.05～0.5mg/L, 0.5¹mg/L, 0.05～0.5mg/L; The ranges of Mn²⁺ optimal concentration for Microcystis aeruginosa and Scenedesmus obiquus were 0.5～5 mg/L , 0.5～5 mg/L.The average concentration of Zn²⁺ was 3.44μg/L, for Fe³⁺ was 0.047 mg/L and for Mn²⁺ was 0.0073mg/L. In this experiment the concentration of Zn²⁺ accelerated the cell division and growth of Microcystis aeruginosa and Scenedesmus obiquus. The concentration of Fe³⁺ also stimulated the propagation of three species of algae. Although the concentration of Mn²⁺ was not the optimal for Scenedesmus obiquus and Scenedesmus obiquus , both the algae also grow well.The investigation of the Miyun Reservoir and AGP experiments indicated that the element of TN& TP played a predominate role in the eutrophication of the Reservoir and the microelement also played a essential role. The concentration of Zn²⁺ , Fe³⁺ & Mn²⁺ had reached the optimal concentration of the propagation of phytoplankton. It accelerated the propagation of phytoplankton and caused the water quality worse along with the other factors. So it is urgent to control the entry of inorganic salt strictly.