【作者】 杨龙；

【导师】 王晓燕；

【作者基本信息】 首都师范大学 ， 自然地理学， 2009， 博士

【摘要】 富营养化是水环境领域中遇到的突出问题。国内外对富营养化从概念、评价方法、发生机理和预测模型等方面进行了大量的研究,然而,对富营养化阈值方面的研究仍不充分,影响了富营养化的评价和防治。本论文从营养盐输入与富营养化响应关系入手,建立了基于营养盐阈值的富营养化风险评价方法体系,设计了模拟目标水体富营养化阈值的流水AGP试验,并选取北京市重要的地表水源密云水库进行实例研究。本文首先界定了富营养化阈值的概念:在水体富营养化过程中,某些限制性营养因子达到一定值后导致水体有机质(浮游生物)供给速率发生跃迁行为,表征这一临界效应的数值称为富营养化阈值。从阈值角度出发,本文定义富营养化为:水体限制性营养因子达到一定的阈值条件下,导致水体初级生产力大幅增加,造成水质恶化的过程。通过对比分析水质参数法、综合指数法、模糊数学法、藻种多样性法等评价方法的优缺点,本文提出了基于目标水体富营养化阈值的评价方法体系,主要内容包括:(1)目标水体富营养化限制因子的判识;(2)确定目标水体富营养化阈值;(3)根据阈值划分水体评价标准;(4)划分风险级别,进行风险评价。多元回归分析发现,透明度、硝酸盐氮、电导率、总磷、总氮与叶绿素a呈显著相关,总磷为密云水库富营养化限制因子。采用分层聚类分析法根据密云水库各监测点指标的相似性,将密云水库监测点划分为四组,其中第一组包括库西、白河主坝,第二组包括水九、潮河主坝、恒河、套里,第三组包括金沟,第四组包括库东。影响密云水库藻生长空间分布的主要因素可以归纳为两类:第一类是以硝酸盐氮、总氮为代表的营养因子,第二类是以水温、电导率、pH值为代表的环境因子。水质状况由好到差的顺序依次为:Group1>Group2>Group4>Group3。选取库东分析时间分布因子,影响藻生长时间分布的主要因素可归纳为三类:第一类是以硝酸盐氮、总氮、总磷为主的营养因子;第二类由总磷、水深、溶解氧、pH等环境因子和营养因子共同作用;第三类由氨氮决定。密云水库浮游藻类结构年内变化明显。通过设计模拟外源输入对富营养化作用的AGP试验装置和方法,模拟了不同环境条件、营养条件下密云水库优势藻种演变和富营养化过程,结合使用MATLAB 7.0数值分析软件,对3期模拟时段的比增长率进行拟合分析,得出3期设计阶段密云富营养化发生的总磷阈值为0.053mg/L、0.062 mg/L、0.064 mg/L,再根据总磷与叶绿素a、总氮、透明度之间的回归关系,划分了密云水库富营养化的评价标准级别。采用WASP生态动力学模型对密云水库叶绿素a进行了数值模拟,结果显示,该模型能较好反映密云水库富营养化过程。最后,采用SPSS13.0统计软件对预测值进行了概率分析,并应用GIS软件对密云水库富营养化发生的风险进行了区划,对防治水体富营养化提出了综合性和前瞻性的对策建议。更多还原

【Abstract】 Eutrophication is a prominent problem encountered in the field of water environment. Even though a great many studies on the concept of eutrophication, evaluation methods, the mechanism and prediction models have been developed both at home and abroad, the research on the threshold for eutrophication is still insufficient, affectting the evaluation and control of eutrophication. In this paper, from the response relationship of eutrophication and nutrients, the risk assessment method system of eutrophication based on the nutriment threshold is found, the flow water AGP test simulatting eutrophication of target water is designed, Miyun Reservoir, the important surface water source in Beijing,is selected as the study case.First, this paper defines the concept of eutrophication threshold: in the process of water eutrophication, some restrictive nutritional factors reach a certain value,and resulted in the transition behavior of the supply rate of organic matter(plankton). Eutrophication threshold denote the value of the critical effect threshold. From the view of threshold value, the definition of eutrophication in this paper is: when the restrictive trophic factor of the water body reaches a certain threshold conditions, primary productivity of the water body increase heavenly, resulting in the process of deterioration of water quality.Through the analysis strongpoint and shortcoming of some evaluatation methods, such as the water quality parameters method, the composite index method, the fuzzy mathematical method,and algal species diversity method, the evaluation method system is proposed in this paper based on eutrophication threshold, the main contents include: (1)identification eutrophication limit factors of target waterbody;(2) identifying the target water eutrophication threshold; (3) division water body evaluation criteria based on threshold; (4) division the risk level, and estimate risk.A significant correlation among the transparency, nitrate nitrogen, conductivity, total phosphorus, total nitrogen and chlorophyll-a is found after Multiple regression analysis, and total phosphorus is considered as eutrophication limiting factor in Miyun Reservoir. Monitoring sites in Miyun Reservoir are divided into four groups in accordance with the similarity of index in each monitoring sites, using hierarchical clustering analysis. The first group includes the kuxi, Baihe main dam;the second group includes Shuijiu, the main chaohe dam, Henghe, Taoli;the third group includs Jingou; the fourth group includes the Kudong. The main factors that affect the spatial and seasonal distribution of the growing algae in Miyun Reservoir can be summed up as two categories: nutritional factors represented by nitrate nitrogen and total nitrogen. The second category are environmental factors represented by water temperature, conductivity, pH value. Water quality from good to poor condition of the order as follows:Group1>Group2>Group4>Group3. After selecting kudong as the site for analysis of the time Distribution factor, the main factors affecting the temporal distribution of algal growth can be summarized into three categories: the first category is nutrient factors mainly comprised of nitrate-nitrogen, total nitrogen, total phosphorus, The second is under a integrate function of the total phosphorus, water depth , dissolved oxygen, dissolved oxygen, pH and other environmental factors and the nutritional factors. The third is determined by the ammonia. It is concluded that phytoplankton structure changes significantly during the year in Miyun Reservoir.Through the design of AGP-test equipments and methods which could simulate the impact of input of exogenous nutrients on eutrophication, the evolution of algae and aquatic species extinction process in Miyun Reservoir under different environmental and nutritional conditions are simulated. Then the ratio growth rate in the three simulation stages are simulated and analyzed combining the numerical analysis software MATLAB 7.0. At last, the conclusion that in the three designed stage, the total phosphorus threshold which leads to a water bloom in Miyun is respctively 0.053mg/L, 0.062mg/L, 0.064 mg/L is educed. Based on the regression relationship of total phosphorus,chlorophyll-a, total nitrogen, and the transparency,we compartmentalized the evaluation standard level of eutrophication in Miyun Reservoir.WASP ecological dynamic model is used for the Miyun Reservoir chlorophyll-a numerical simulation. And the results revealed that the model is preferable to reflect the eutrophication process of Miyun Reservoir. Finally, the probability analysis of prediction value as well as the zoning of the risk of eutrophication in Miyun Reservoir is carried out using the statistical software SPSS13.0; the paper provides a comprehensive and forward-looking way preventing against eutrophication of waterbody.更多还原