长江武汉江段磷垂向分布规律研究

发布时间：2018-01-11 08:12

本文关键词：长江武汉江段磷垂向分布规律研究　出处：《长江科学院》2017年硕士论文　论文类型：学位论文

【摘要】：河流水体中的磷是水生生物生长和繁殖所需的必备元素,其输移的连续性对维持流域生态系统的健康和稳定具有不可替代的作用。长江中游河段水体中磷大多以颗粒磷形式存在,具有垂向分布不均匀性特征。长江上游大型水库修建,拦截了大量泥沙,导致中游悬沙含量减小,悬沙浓度垂向分布发生变化,与悬沙关系密切的颗粒磷垂向分布也发生变化,磷垂向分布的变化会对长江中游河段水生生物的栖息环境产生影响,长江为大江大河,河道断面较大,断面表层和底层的悬沙浓度、磷浓度有一定差异。因此,有必要针对河流水体磷浓度垂向分布开展深入研究,并在此基础上进一步研究河流磷通量的计算方法,为准确掌握水库工程对河流营养物质传输影响提供科学依据。本文以长江中游典型河段武汉江段中磷为研究对象,通过现场调查,研究了磷垂向分布特征和现状;筛选了长江中游武汉江段悬沙垂向分布公式,并引入颗粒磷浓度与悬沙的定量关系式,建立了武汉江段中颗粒磷和总磷浓度垂向分布计算模型;根据河流磷的垂向分布,建立了磷通量计算方法。本文主要结论如下:(1)根据长江中游武汉江段悬沙实测调查数据分析显示,无论丰、平水期,武汉江段悬沙浓度和泥沙粒径垂向上随水深增加呈增大趋势。其中悬沙浓度垂向增幅为3.93%-52.6%,悬沙粒径垂向增幅相对较小,大都在3.6%-13.06%。(2)根据长江中游武汉江段磷实测调查数据分析显示,无论丰、平水期,武汉江段总磷和颗粒磷在垂向上呈增大趋势,溶解磷在垂向上分布较均匀。武汉江段总磷浓度为0.071-0.223mg/L,垂向增幅为6.5%-82.9%;颗粒磷浓度为0.031-0.178mg/L,垂向增幅为4.1%-85.5%;溶解磷浓度为0.021-0.128mg/L,垂向上分布较均匀。(3)长江中游悬沙垂向分布模型采用Rouse公式,利用武汉江段悬沙实测数据拟合,该模型公式决定系数达到0.945,拟合精度较高。(4)以Langmuir吸附等温式为基础,利用武汉江段颗粒磷与悬沙浓度的实测值,拟合得到颗粒磷与悬沙浓度的定量关系式,与上述悬沙垂向分布模型公式相结合,推导出长江中游颗粒磷与总磷垂向分布模型公式,该公式计算值与实测值相对误差为1.4%-25.1%,精度相对较高。(5)在总磷垂向分布计算模型基础上,进一步推导出长江中游武汉江段磷通量计算模型公式。该公式计算值与实测值相对误差为0.3%-11.1%,磷通量计算精度较高。
[Abstract]:Phosphorus in river water is an essential element for the growth and reproduction of aquatic organisms. The continuity of transport plays an irreplaceable role in maintaining the health and stability of the watershed ecosystem. The phosphorus in the middle reaches of the Yangtze River exists mostly in the form of particulate phosphorus. The large reservoir in the upper reaches of the Yangtze River intercepts a large amount of sediment, which leads to the decrease of suspended sediment content in the middle reaches and the change of vertical distribution of suspended sediment concentration. The vertical distribution of particulate phosphorus which is closely related to suspended sediment also changes. The change of vertical distribution of phosphorus will affect the habitat of aquatic organisms in the middle reaches of the Yangtze River. The Yangtze River is a big river with a large river section. There are some differences in suspended sediment concentration and phosphorus concentration between the surface and bottom layers of the section. Therefore, it is necessary to further study the vertical distribution of phosphorus concentration in river water, and further study the calculation method of river phosphorus flux. In order to provide a scientific basis for accurately understanding the effects of reservoir engineering on the transport of nutrients in rivers, this paper takes the phosphorus in the typical reach of Wuhan in the middle reaches of the Yangtze River as the research object and makes a field investigation. The characteristics and present situation of phosphorus vertical distribution were studied. The vertical distribution formula of suspended sediment in Wuhan reach in the middle reaches of Yangtze River was selected, and the formula of quantitative relationship between particulate phosphorus concentration and suspended sediment was introduced, and the vertical distribution model of particulate phosphorus and total phosphorus concentration was established. According to the vertical distribution of phosphorus in the river, the calculation method of phosphorus flux is established. The main conclusions of this paper are as follows: 1) according to the survey data of suspended sediment in Wuhan reach of the middle reaches of the Yangtze River, it is found that there is no matter whether it is abundant or flat. The vertical increase of suspended sediment concentration and sediment particle size in Wuhan reach shows an increasing trend with the increase of water depth, and the vertical increase of suspended sediment concentration is 3.93-52.6, and the vertical increase of suspended sediment particle size is relatively small. Most of them are in 3.6- 13.060.2.According to the survey data of phosphorus in Wuhan section in the middle reaches of the Yangtze River, the results show that the total phosphorus and particulate phosphorus of Wuhan reach are increasing in vertical direction, no matter if they are abundant or flat. The total phosphorus concentration in Wuhan reaches 0.071-0.223mg / L, and the vertical increase is 6.5- 82.9; The particle phosphorus concentration was 0.031-0.178 mg / L, and the vertical increase was 4.1-85.5; The concentration of dissolved phosphorus is 0.021-0.128 mg / L, and the vertical distribution of suspended sediment in the middle reaches of the Yangtze River is more uniform. The Rouse formula is used in the vertical distribution model of suspended sediment in the middle reaches of the Yangtze River. According to the measured data of suspended sediment in Wuhan reach, the determination coefficient of the model is 0.945, and the fitting precision is high. 4) based on the isothermal equation of Langmuir adsorption. Based on the measured values of particulate phosphorus and suspended sediment concentration in Wuhan, the quantitative relationship between particulate phosphorus and suspended sediment concentration is obtained, which is combined with the vertical distribution model of suspended sediment. The vertical distribution formula of particulate phosphorus and total phosphorus in the middle reaches of the Yangtze River is derived. The relative error between the calculated value and the measured value is 1.4% -25.1%. The accuracy is relatively high. 5) based on the vertical distribution model of total phosphorus. A formula for calculating phosphorus flux in Wuhan reach of the middle reaches of Yangtze River is derived. The relative error between the calculated value and the measured value is 0.3-11.1, and the calculation accuracy of phosphorus flux is high.
【学位授予单位】：长江科学院
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P342;X143

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