Modelling Analysis Of Eutrophic Elements And Their Speciation For Wuliangsuhai Lake In Inner Mongolia

More and more attention has been paid to eutrophication of lakes throughout the world in terms of one of the global environmental problems. The research on nitrogen and phosphor was regarded very important during renewing and controlling eutrophication of lakes. The research on nitrogen and phosphor were most in studies on eutrophication. Commonly, an ordinary object is studied by two aspects. They are quantity and quality. The research on nitrogen and phosphor are so. However, today the research on nitrogen and phosphor are concentrated on quantity. For example, founding eutrophic models, transferring, circulation, sediment and releasing about eutrophic elements. The abundant achievements were obtained. However, it was end of research on eutrophic elements that results on quantity of eutrophic elements are known. The research on forms of eutrophic elements were ignored. There were some studies on forms of eutrophic elements, but they were studies on eutrophic elements in sediment of lakes by a lot of experiments. In this paper, Wuliangsuhai Lake (WL) is study area. On the bases of information on quantity of nitrogen and phosphor in water of WL, the forms of eutrophic elements are simulated and analyzed by the theories and knowledge of geochemistry. So, the main content as below:Firstly, the pollution mechanism and the status quo of WL are studied and analyzed. The water quality data combined with the spatial data are analyzed using the method of Principal Components Analysis. The water quality parameters of WL are summarized into seven principal components. The meaning of each principal component and the pollution mechanism of WL with considering character on arid region are discussed and analyzed. The special reasons that the pollution mechanism of typical weedy shallow lakes in arid and semiarid region is different from in wet and semi wet region are obtained. It is very important for the research on quantity of eutrophic elements and founding eutrophic models to research quantificational and spacial distribution of eutrophic elements in lakes. The spacial estimate and analysis on variability of total nitrogen (TN) and total phosphor (TP) are analyzed by IDW (inverse distance to a power), Kriging and MC (minimum curvature). Based on the comparing results and checking by experiment data of water samples, it shows the Kriging better make use of special variability of water samples than others, and the error of Kriging is least. The conclusion is that the Kriging is best method to calculate spacial distribution of eutrophic elements in WL. The pollution status quo of WL are analyzed by data of different indexes in 2005.On the bases of the pollution mechanism and the status quo of WL, the models on quantity of eutrophic elements are founded and applied. Base on two-dimensional hydrodynamic model of lakes, the factors of special hydrometeorologic condition in arid region include evaporation and wind speed are joined into the model. The models are suitable to research hydrodynamics of lakes in arid and semiarid region. Then, the horizontal, two-dimensional, dynamical and determinate models are selected to simulate the concentration of eutrophic elements (TN and TP) of water in WL. The parameters of models are selected with considering the character of lakes in arid and semiarid region. The models are applied and validated by the experiment data of concentration of TN and TP. During simulating flow field, the models are calculated with inputting of daily data of the evaporation intension coefficient and wind speed. So, the error that is made by ignored the randomicity of evaporation and wind is avoided, and the precision of result on simulation is high. The models can more accurately describe the hydrodynamic process of lakes in arid region. The results show that the influence on water deep by evaporation and wind can be ignored, but the influence on flow field cannot be ignored. Intense evaporation can accelerate velocity of flow. The influence on velocity of flow by wind lies on wind speed and wind direction. So, it is necessary for research on water environment of lakes in arid and semiarid region to consider the influence on flow field by evaporation and wind. It can influence on distributing and variety of concentration of contamination. During the process of simulation concentration field of TN and TP of water in WL, the parameters are decided with considering the change of water quality in different seasons, and the precision of parameters is heightened. The concentration field of TN and TP are obtained by calculating models. The main reasons on variety of concentration of TN and TP are analyzed by comparing initialized concentration field with simulated concentration field. The rationality and precision of models are proved by applying and checking in modeling area in WL. The models are suitable to research on hydrodynamics and the variety of concentration field of eutrophic elements of WL in arid region. It is important to institute measures on fathering eutrophication of lakes.At last, the forms of eutrophic elements are researched. On the bases of character of quantity on eutrophic elements (nitrogen and phosphor) in WL, the forms of eutrophic elements are researched by the theories and knowledge of geochemistry. The essential of transforming among different forms of nitrogen and phosphor is the process of gain and loss of electron and hydrogen ion with caloric transform. So, software of geochemistry, PHREEQC is selected. The forms of nitrogen and phosphor are simulated in condition with different pH, temperature and pe. The simulation that quantity and forms of eutrophic elements are coupled is realized in state with different physical and chemic indexes. The result of simulation is validated by experiment data. The results show that PHREEQC can be applied on simulating different forms of eutrophic elements. In this paper, it is primary attempt to apply PHREEQC to study forms of elements of water environment in lakes. It is very necessary to apply knowledge of geochemistry to study water environment in lakes and its trend of research is favorable. The advices that father eutrophication of WL are given after combining the character of quantity and quality of eutrophic elements in WL.Eutrophic elements (nitrogen and phosphor) in WL are regard as main indexes. The research on quantity and forms of eutrophic elements not only is important to control pollution and eutrophication of WL, but also is cumulation of knowledge and experience about fathering water environment of lakes in arid and semiarid region. It is important to protect water resource and ameliorate water environment in arid and semiarid region.