The Nitrogen And Phosphorus Absorption Effect Of Azolla Imbricata In Different Nitrogen,Phosphorus Concentrations, Temperature

Lake Erhai is one of the eutrophication shallow lakes in our country, eutrophication has led to the aquatic vegetation dominant populations’ replacement, even recession and demise. Eutrophication is mainly caused by the water’s nitrogen, phosphorus and other nutrients excess nutrients. So it is a great significance of researching the relationship between the nutrient enrichment of aquatic plant and eutrophication. It is also important to study the growth of aquatic plants under the different concentration of nitrogen and phosphorus in water environment. This paper used the Azolla in the the Erhai Lake to study the removal of nitrogen and phosphorous in different phosphorus concentration gradient and its growth situation, trying to analysis and explore the absorption of aquatic plants Azolla in different water environment conditions. Then discussed whether could Azolla be a dominant species to control the lake eutrophication in the future. The results of this study are as the following:1. The concentration of phosphorus too high or too low are not conducive to the growth of the Azolla, when the phosphorus concentration is about0.1mg/L suitable for the growth of the Azolla; The color and growth condition of Azolla are different, the removal of nitrogen and phosphorus in water is same, for the water of phosphorus, the removal efficiency are very significant;when organophosphorus concentration at about0.5mg/L is conducive to the growth of the Azolla; Azolla also has very good removal effect for the organic phosphorus in the water.2. Azolla’s favorable temperature is from20to25℃; Azolla could absorb phosphorus in water greatly, but affected by the interaction of temperature and the phosphorus concentration in water, namely, with the increase of phosphorus concentration and temperature, the phosphorus uptake were increasing but absorption rate were declined; The Azolla’s favorable condition of phosphorus absorption was25℃and phosphorus concentration was0.075mg/L.3. Azolla’s growth was affected by the source of nitrogen in water,it favored ammonia nitrogen than nitrate, and it’s favorable concentration of ammonia was2mg/L. The percent of tissue nitrogen in Azolla by nitrogen fixation was declined with increase of nitrogen concentration in water.Azolla was not only a good species to remove nitrogen and phosphorus from water, but also a high nutritional food for livestock. So Azolla could bring some ecological and economic value during the control process of lake eutrophication. It is a good potential aquatic plant species to remove nitrogen...