山地城市封闭水体氮磷敏感点识别方法研究
发布时间：2018-08-30 11:49
【摘要】：湖泊的富营养化问题是全球关注的湖泊热点问题之一,而水体中氮磷的含量则是影响富营养化程度的主要因素。山地城市封闭水体除具有流动性差、水生态系统简单、水环境容量小等特点,还具有水位深、受风生流扰动较小、存在温跃层以及密度流等特点。水深、温度以及水流条件等因素,均对氮磷在水体中的分布具有重要的影响作用。论文以位于山地城市重庆的龙景湖为研究对象,详细调查了龙景湖的区域概况并评价了龙景湖水质及富营养化现状,探究了山地城市封闭水体中总氮、总磷浓度与水深的响应关系,并通过EFDC水环境模型对龙景湖总氮、总磷分布特征进行了模拟,分析找出了龙景湖氮磷敏感点位置,建立了氮磷敏感点识别方法。主要研究结论如下:①根据龙景湖水动力条件等因素,将龙景湖分为A、B、C、D、E五个区域。基于三年来对龙景湖的实测水质数据,对龙景湖水质现状以及富营养化现状进行了分析。A、B、C区总磷浓度在0.05mg/L~0.23mg/L之间变化,其中10月份至次年2月份,总磷浓度均在0.1mg/L以上。D、E区总磷含量在秋冬超过了0.1mg/L的标准。总氮含量A、B、C区相对稳定,仅2月份出现超标现象。D区总氮含量10月至2月存在超标现象,而E区总氮含量则非常高,全年有一半的时间总氮浓度高于1.5mg/L。龙景湖全年平均TLI指数为57.69,处于轻度富营养化状态,其中6、7、9以及2月处于中度富营养化状态,平均TLI指数为63.68。②对龙景湖A、B、C、D、E五个分区中氮磷浓度与水深的响应特性进行了研究。不同分区、不同采样时间以及不同水质指标之间,响应关系均存在差异。其中,8月15日和9月4日龙景湖区域B中水深与总磷含量的拟合曲线拟合优度值最高,分别达到0.997和0.992,响应关系最为明显。这可能是由于不同分区水流环境不同、湖泊底泥类型存在差异、气温变化、风速风向改变、污染物在水中的主要存在形态以及物质扩散系数等因素造成的。③在对扩散原理充分认识的基础上,基于费克定律扩散方程以及Mike-Chang扩散系数经验方程等科学定律和经验方程式,推导出污染物浓度与水温以及水深之间的关系方程式C_A=y_2e~z/(y_1T)+x_2,并运用MATLAB(matrixlaboratory)矩阵实验室进行二元非线性拟合,计算出该关系式中的未知系数,分别得到总氮、总磷的具体方程形式,其中总氮方程的拟合优度为0.714,平均相对误差为12.96%,总磷方程的拟合优度为0.662,平均相对误差为23.16%。对龙景湖中总氮浓度以及总磷浓度随水深的变化情况的具体计算,表明总氮与总磷含量均随水深的增加而上升。并且,在自然环境下,垂向温度变化对总氮、总磷浓度变化影响十分微小。④通过EFDC(Environmental Fluid Dynamics Code)水环境模型,构建龙景湖的水动力、水质模型。为研究龙景湖在无外来污染源进入的情况下,总氮以及总磷在龙景湖水动力条件、底泥吸释等湖体自身因素影响下的分布特征,在建立模型的过程中,污染物的输入量被设置为0。模型结果表明,在龙景湖自身水流条件等因素的作用下,总磷最易集聚的区域为D区,秋冬总氮积聚的区域为D区,而春夏则为E区。⑤通过对龙景湖氮、磷垂向分布情况以及空间分布情况的模拟,分析指出龙景湖中对湖体氮、磷浓度上升最为敏感的点。就总氮而言,具有一定的季节性。秋冬季节,对湖体总氮浓度上升表现得最为敏感的点为区域D的A10取样点,而春夏季节对水中总氮浓度上升最为敏感的点为E区域的A08点。总磷全年分布较为稳定,对湖体中总磷浓度升高最为敏感的点为区域D的A09以及A10点。取样点垂向上总氮、总磷浓度敏感性则以水深为依据,水深越深,总氮、总磷越容易富集。
[Abstract]:The eutrophication of lakes is one of the hotspots in the world, and the content of nitrogen and phosphorus in the water body is the main factor affecting the degree of eutrophication. The distribution of nitrogen and phosphorus in the water body is affected by water depth, temperature and flow conditions. The Longjing Lake, located in the mountainous city of Chongqing, is investigated in detail, and the water quality and eutrophication status of Longjing Lake are evaluated. The response relationship between total nitrogen and total phosphorus concentration and water depth in closed water body was studied. The distribution characteristics of total nitrogen and total phosphorus in Longjing Lake were simulated by EFDC water environment model. The location of nitrogen and phosphorus sensitive points in Longjing Lake was analyzed and identified, and the identification method of nitrogen and phosphorus sensitive points was established. The lake is divided into five regions: A, B, C, D and E. Based on the measured water quality data in the past three years, the water quality and eutrophication status of Longjing Lake are analyzed. Total nitrogen content in area A, B and C was relatively stable, but exceeded the standard only in February. Total nitrogen content in area D exceeded the standard from October to February, while total nitrogen content in area E was very high. The annual average TLI index of Longjing Lake was 57.69, which was slightly eutrophic in June, July, September and February. The average TLI index was 63.68. The goodness-of-fit value of the fitting curve was the highest, reaching 0.997 and 0.992 respectively, and the response was the most obvious. This may be due to the different water flow environment, different types of Lake sediment, changes in temperature, wind speed and direction, the main forms of pollutants in the water and the diffusion coefficient of substances. On the basis of full understanding of diffusion principle, the equation C_A=y_2e~z/(y_1T)+x_2 of the relationship between pollutant concentration and water temperature and water depth is deduced based on the diffusion equation of Fick's law and Mike-Chang's empirical equation of diffusion coefficient. The binary non-linear equation is carried out by using MATLAB (matrix laboratory) matrix laboratory. The unknown coefficients in the equation were calculated, and the specific equations of total nitrogen and total phosphorus were obtained. The goodness of fit of the equation was 0.714, the average relative error was 12.96%, the goodness of fit of the equation was 0.662, and the average relative error was 23.16%. The calculation shows that the total nitrogen and total phosphorus content increase with the increase of water depth, and the vertical temperature has little effect on the total nitrogen and total phosphorus concentration in natural environment. The distribution characteristics of total nitrogen and phosphorus under the influence of hydrodynamic conditions and sediment suction and release in Longjing Lake were studied. In the process of establishing the model, the input of pollutants was set to 0. The vertical distribution and spatial distribution of nitrogen and phosphorus in Longjing Lake were simulated. It was pointed out that the most sensitive point to the increase of nitrogen and phosphorus concentration in Longjing Lake was the point where the concentration of nitrogen and phosphorus in the lake increased. As far as total nitrogen was concerned, it had a certain seasonality. The most sensitive point is A10 sampling point of region D, and A08 sampling point of region E is most sensitive to the increase of total nitrogen concentration in spring and summer. According to the deeper water depth, total nitrogen and total phosphorus are more easily enriched.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X524
本文编号：2212980
[Abstract]:The eutrophication of lakes is one of the hotspots in the world, and the content of nitrogen and phosphorus in the water body is the main factor affecting the degree of eutrophication. The distribution of nitrogen and phosphorus in the water body is affected by water depth, temperature and flow conditions. The Longjing Lake, located in the mountainous city of Chongqing, is investigated in detail, and the water quality and eutrophication status of Longjing Lake are evaluated. The response relationship between total nitrogen and total phosphorus concentration and water depth in closed water body was studied. The distribution characteristics of total nitrogen and total phosphorus in Longjing Lake were simulated by EFDC water environment model. The location of nitrogen and phosphorus sensitive points in Longjing Lake was analyzed and identified, and the identification method of nitrogen and phosphorus sensitive points was established. The lake is divided into five regions: A, B, C, D and E. Based on the measured water quality data in the past three years, the water quality and eutrophication status of Longjing Lake are analyzed. Total nitrogen content in area A, B and C was relatively stable, but exceeded the standard only in February. Total nitrogen content in area D exceeded the standard from October to February, while total nitrogen content in area E was very high. The annual average TLI index of Longjing Lake was 57.69, which was slightly eutrophic in June, July, September and February. The average TLI index was 63.68. The goodness-of-fit value of the fitting curve was the highest, reaching 0.997 and 0.992 respectively, and the response was the most obvious. This may be due to the different water flow environment, different types of Lake sediment, changes in temperature, wind speed and direction, the main forms of pollutants in the water and the diffusion coefficient of substances. On the basis of full understanding of diffusion principle, the equation C_A=y_2e~z/(y_1T)+x_2 of the relationship between pollutant concentration and water temperature and water depth is deduced based on the diffusion equation of Fick's law and Mike-Chang's empirical equation of diffusion coefficient. The binary non-linear equation is carried out by using MATLAB (matrix laboratory) matrix laboratory. The unknown coefficients in the equation were calculated, and the specific equations of total nitrogen and total phosphorus were obtained. The goodness of fit of the equation was 0.714, the average relative error was 12.96%, the goodness of fit of the equation was 0.662, and the average relative error was 23.16%. The calculation shows that the total nitrogen and total phosphorus content increase with the increase of water depth, and the vertical temperature has little effect on the total nitrogen and total phosphorus concentration in natural environment. The distribution characteristics of total nitrogen and phosphorus under the influence of hydrodynamic conditions and sediment suction and release in Longjing Lake were studied. In the process of establishing the model, the input of pollutants was set to 0. The vertical distribution and spatial distribution of nitrogen and phosphorus in Longjing Lake were simulated. It was pointed out that the most sensitive point to the increase of nitrogen and phosphorus concentration in Longjing Lake was the point where the concentration of nitrogen and phosphorus in the lake increased. As far as total nitrogen was concerned, it had a certain seasonality. The most sensitive point is A10 sampling point of region D, and A08 sampling point of region E is most sensitive to the increase of total nitrogen concentration in spring and summer. According to the deeper water depth, total nitrogen and total phosphorus are more easily enriched.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X524
【参考文献】
相关期刊论文 前1条
1 孙学成,邓晓龙,张彩香,潘娟琴;WASP6系统在三峡库区水质仿真中的应用[J];三峡大学学报(自然科学版);2003年02期
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