【作者】 史小红；

【导师】 李畅游；

【作者基本信息】 内蒙古农业大学 ， 农业水土工程， 2007， 博士

【摘要】 湖泊富营养化是全球普遍关注的环境问题之一,在富营养化湖泊的恢复与治理研究中,氮、磷污染是研究的焦点,因此,关于富营养化研究最多的就是营养元素—氮、磷的内容。对于一般事物进行其特性研究时,都要从“量”与“质”两方面进行,营养元素—氮、磷的研究也不例外。目前国内外关于氮、磷的研究主要集中在数量上,表现在:富营养模型的建立、营养物质的迁移、循环、沉积与释放等,并取得了大量的研究成果。然而这些研究基本是摸清营养元素数量后就是关于营养元素研究的结束,都忽略了营养元素存在形态的研究。有单方面进行营养元素存在形态的研究也都集中在以大量实验分析为基础,进行湖底沉积物中氮、磷形态的分析。本文以乌梁素海为研究对象,在掌握湖泊水质中氮、磷数量信息的基础上,利用地球化学的理论、知识,进一步对水中营养元素—氮、磷的存在形态进行了模拟分析。首先对乌梁素海的污染机理及污染现状进行了研究分析。将实测的湖泊水质监测数据与空间数据结合,采用基于因子分析的主成分方法将乌梁素海的水质参数概括为7个主成分,进一步分析讨论各主成分的科学内涵以及结合地区特征的湖泊污染机理,得到了在干旱半干旱地区典型的草型浅水湖泊其污染机理不同于湿润半湿润地区湖泊的特殊原因。在进行营养营养元素数量研究而建立湖泊富营养模型时,首先对营养元素在湖泊的空间分布进行定量研究,分别采用反距离加权插值法、克里金插值法和最小曲率法进行湖泊总氮、总磷浓度的空间估值与变异性分析,通过计算结果对比及实测数据的验证,选择克里金方法是最适合乌梁素海水体中营养元素的空间分布的计算方法。并通过2005年对于乌梁素海各项指标实测数据的统计、整理、内插,分析了湖泊的污染现状。其次,在了解了乌梁素海污染机理及污染现状的基础上,关于营养元素数量研究进行了模型的建立与应用。以湖泊水平二维水动力学模型为基础,考虑干旱区特殊的水文气象因素,将蒸发、风力考虑进模型中,建立适合干旱区湖泊水动力学的模型。在水动力学模型的基础上选择水平二维、动态、确定型模型对干旱区非均匀混合型湖泊水质营养元素总氮、总磷浓度进行模拟。并针对干旱区湖泊所在地域的特点,率定了模型中的参数。利用湖泊水质中总氮、总磷浓度的实测值进行了模型的应用与验证。进行流场模拟时,在数值计算过程中将蒸发强度系数和风速采用逐日数据分别输入模型进行计算,避免了因忽略实际过程中蒸发与风的随机性而引起的误差,提高了模拟结果的精确度,能够更准确地描述该地区中湖泊的水动力过程。结果显示蒸发和风因素对湖泊水深影响可忽略,但对湖泊流场影响较大,强烈的蒸发使水流流速增大,风对流速的影响取决于风速大小和方向两个因素,因此在干旱半干旱地区进行湖泊水环境研究时应考虑蒸发和风因素对湖泊流场的影响,从而影响到不同污染物浓度分布变化。在模拟湖泊水质中总氮、总磷的浓度场时,考虑湖泊水质随季节变化大而进行参数率定以提高其准确度,经过模型的计算得出了总氮、总磷的浓度场,根据总氮、总磷的初始浓度场与模拟浓度场比较与分析,得出引起总氮、总磷浓度变化的主要原因。通过对乌梁素海建模区的应用与检验证明了所建模型的正确合理性与精确度。模型对于定量描述地处干旱半干旱地区的乌梁素海湖泊水动力学及营养元素浓度场的变化是非常适用的,这样对合理制定湖泊富营养化治理措施提供科学依据具有重要意义。最后对富营养元素存在形态进行了进一步的模拟研究。在摸清乌梁素海湖泊中营养元素—氮、磷的数量特征的基础上,研究尝试用地球化学中的理论、观点、知识去研究湖泊水体中富营养元素—氮、磷的存在形态。氮元素中的无机氮和磷元素中的正磷酸磷中不同形态的相互转化实质是电子和氢离子得失的过程,并伴随着热量的转化,研究选择利用地球化学软件—PHREEQC,进行了湖泊水环境在不同pH值、温度、pe值条件下对无机氮中应存在的形态氮和可溶性正磷酸盐中应存在的形态磷进行了模拟,实现了湖泊物理、化学指标在不同状态下与富营养元素的存在数量与形态的耦合模拟,并用大量的实测数据进行分析验证,结果说明PHREEQC可用于湖泊营养元素各种形态的模拟。同时也是PHREEQC在湖泊水环境中对物质存在形态应用研究的初步尝试,笔者认为将地球化学学科知识应用到湖泊水环境的研究是非常必要的,并且具有广阔的研究前景。之后结合湖泊中营养元素的“量”与“质”的特征,给出了乌梁素海富营养化治理的建议。以乌梁素海水体中营养元素—氮、磷为主要研究指标,摸清其数量及存在形态,不仅对于控制乌梁素海水污染和富营养化有重要作用,也是对干旱半干旱地区湖泊水环境治理的知识和经验的积攒,对于保护干旱半干旱地区水资源与改善水环境都具有重要的作用和意义。更多还原

【Abstract】 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.更多还原