Research On Effects Of Cerium Of Rare Elements On The Growth And Physiological Characteristics Of Anabaena Flos-aquae

China began to use rare earth in agriculture in1970s. Subsequently, it is widely used in various fields and is called industrial monosodium glutamate. So people pay more attention to its effects on aquatic ecology. Eutrophication not only due to excessive input of nutrient, trace elements may also lead to algal blooms and result in water bloom. Anabaena flos-aquae is the dominant species of water bloom, while Cerium is the most abundance element in rare earth and it is also the main elements of micro fertilizer. In this paper, effects of different concentrations of Ce3+on the growth, the contents of photosynthetic pigments, osmoregulation substances and malondialdehyde (MDA), the activities of antioxidant emzymes of Anabaena flos-aquae were studied by simulated test in laboratory. At the same time, the concentration of total nitrogen (TN), total phosphorus (TP), microcysin-LR (MC-LR) and residual Cerium in the medium also were determined. The main results were shown as follows:(1) The growth of Anabaena flos-aquae was stimulated at lower concentrations of Ce3+(0.01-0.5mg/L), while Ce3+had inhibitory effect on the growth of Anabaena flos-aquae at higher concentrations (1～10mg/L). Under the level of0.10mg/L, the quantity of Anabaena flos-aquae was significant than other groups (p=0.008) and when the concentration of Ce3+approached10mg/L, the growth of Anabaena flos-aquae was significantly inhibited (p<0.01). The Hormesis effect of Cerium on Anabaena flos-aquae was obvious.(2) The contents of chlorophyll a, phycocyanin and carotenoids were increased at lower concentrations of Ce3+, wlile the contents of chlorophyll a, phycocyanin and carotenoids were inhibited at higher concentrations of Ce3+. And the content of photosynthetic pigment increased as the experiment progress.(3) With the increasing of Ce3+concentration, the content of soluble carbohydrate decreased at the beginning, and increased subsequently, and declined as the experiment progress. However, the soluble protein showed the opposite trend.(4) The activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) were higher and the content of malondialdehyde (MDA) was lower than control at low concentrations of Ce3+. Under high concentrations of Ce3+stress, the lipid peroxidation of algae cell was serious, the content of MDA was significantly elevated and the activities of SOD, POD, CAT were reduced.(5) Because of Anabaena flos-aquae is nitrogen-fixing cyanobacteria, the effect of Ce3+on it from medium intake TN had no obvious law. The trend of Anabaena flos-aquae intake TP showed that low concentration of Ce3+accelerate the absorption of TP, high concentration of Ce3+inhibit.(6) The contents of MC-LR were lower than the China Standard (1.00ug/L) in all culture medium. Compared with control, the deaths of algal cells increased and released a large number of MC-LR under high concentration of Ce3+.(7) The rate of reduction of Ce+was more than50%in all treatment groups. When the initial concentrations were1～10mg/L, the rate of reduction were greater than90%.