海河流域典型河流滏阳河中氮赋存形态及氨氮转化特征研究

发布时间：2019-06-19 18:21

【摘要】：海河流域地处我国北方经济的核心地区。由于流域经济社会的快速发展,城市化进程的加快,以及流域内水资源禀赋天然不足,导致其成为我国极度缺水和严重污染的流域之一,其中以氮污染最为突出。研究海河流域典型河流滏阳河氮污染特征,对河流氮污染治理以及河流生态修复具有重要的意义。同时,氮素作为生物有机体的组成元素,其在河流生态系统中的地球化学循环与河流氮污染问题有着密切的联系。本研究主要针对海河流域典型河流滏阳河严重的氮污染问题,通过对滏阳河水体和沉积物中氮素的赋存形态和分布特征的研究,展现了滏阳河氮污染的近况和特点；并选择滏阳河各段具有代表性的样点分析沉积物孔隙水和上覆水中无机氮的分布特征和形态组成,估算水—沉积物界面无机氮的扩散通量和年负荷贡献量,探明外源污染物的排放和沉积物内源释放对河流水体水质的影响；然后针对滏阳河“高氨氮”的污染特性,通过研究表层沉积物氨化速率、潜在硝化速率(Potential Nitrification Rate, PNR)以及沉积物对氨氮的吸附—解吸特征,揭示了沉积物氨氮的迁移转化过程。研究结果表明：(1)滏阳河表层水TN的平均浓度为24.95mg/L,超出国家地表水V类标准；表层沉积物TN的平均浓度为2902.02mg/kg,达到美国EPA沉积物评价标准的重污染程度。表层水氮素的主要赋存形态为可溶性无机氮(DIN),其中NH4+-N为主要污染成分,占DIN的83.6%。表层沉积物则以有机氮为主要存在形态,其占TN的89.02%；而DIN的主要赋存形态是NH4+-N,所占比例达到54.88%。相关性分析表明,滏阳河表层水和沉积物中各形态氮之间以及理化指标对不同形态氮含量和分布具有一定的影响,另外,表层水和沉积物中氮的赋存形态和含量也可以互相影响。(2)滏阳河上覆水和孔隙水中DIN的赋存形态仍以NH4+-N为主,其占DIN的比例分别达到96.4%和94.2%。在垂直尺度上,上覆水NH4+-N、NO3--N和NO2--N的浓度随深度增加基本保持稳定,而孔隙水中其波动较大,并且NH4+-N和NO3--N均在0-10cm范围内出现最大值。此外,NO2--N由于其不稳定性,在孔隙水呈现明显的波动性。在空间尺度上,上覆水和孔隙水中无机氮仍以石家庄段最为严重。滏阳河水-沉积物界面无机氮的扩散通量和年负荷贡献量具有明显的空间差异性。对于扩散通量,除了N02--N在整个滏阳河表现为从沉积物向上覆水释放外,其余均表现为不一致的“源”、“汇”特征,表明滏阳河沉积物存在一定的氮污染物的释放风险。在石家庄段,氨氮的扩散通量达到.42.18 mg/(m2·d),外源污染年负荷贡献量达到101.62t/a,说明该河段受氨氮外源污染严重。因此,对滏阳河治理在控制外源排放的同时,内源负荷也是不容忽视的。(3)滏阳河表层沉积物氨化速率和潜在硝化速率的平均值分别为4.30μgN/(g·h)和0.152μg N/(g·h),前者约为后者的28倍。与其他研究结果相比,滏阳河氨化速率和PNR的变化范围较大,具有明显的空间差异性。表层沉积物NH4+-N的吸附动力学过程符合抛物线扩散模型和修正的Elovich模型,包括快速吸附和吸附平衡两个阶段,前者在前120min完成,而后逐渐达到吸附平衡。在低浓度是,滏阳河表层沉积物NH4+-N的等温吸附曲线满足Henry模型,其拟合程度达到了极其显著的效果,并得出沉积物的吸附—解吸平衡浓度在0.55-26.15mg/L之间,沉积物的本底吸附量介于8.181-402.68mg/kg之间。除S07外,各个采样点用Langmuir等温平衡吸附模型拟合的效果较好,沉积物对NH4+-N的最大吸附量在429.10-1162.60mg/kg之间。而Freundlich模型对数据无法拟合。滏阳河表层沉积物对NH4+-N的解吸特性与吸附动力学特性相似,但其达到吸附平衡需要6h。除S07外,其余各点均可用一级动力学方程进行拟合。另外,各点的平衡解吸量的变化范围为36.50-400.59mg/kg。滏阳河表层沉积物的平衡解吸量与TN、NH4+-N和C/N值具有一定的相关性。
[Abstract]:The Haihe river basin is located in the core area of the northern economy of our country. As a result of the rapid development of the economic and social development of the basin, the acceleration of the urbanization process, and the natural shortage of the natural resources of the water resources in the basin, it has become one of the most severe water shortage and serious pollution in our country, in which the nitrogen pollution is the most prominent. It is of great significance to study the characteristics of the pollution of the water and nitrogen in the typical rivers in the Haihe river basin, and it is of great significance to the river and nitrogen pollution treatment and the river ecological restoration. At the same time, nitrogen is a component of the biological organism, and its geochemical cycle in the river ecosystem is closely related to the problem of river and nitrogen pollution. The present study mainly aims at the problem of the serious nitrogen pollution of the typical river in the Haihe river basin, and through the study of the form and distribution of the occurrence and distribution of the nitrogen in the water body and sediment of the Xianyang river basin, the present situation and the characteristics of the pollution of the river and nitrogen in the basin are presented. and the distribution characteristics and the form of the inorganic nitrogen in the water and the overlying water are analyzed by the representative sample points in the sections of the Youyang River, and the diffusion flux and the annual load contribution amount of the inorganic nitrogen in the water and sediment interface are estimated, The effects of the emission of foreign pollutants and the endogenous release of the sediment on the water quality of the river water were studied, and then the characteristics of the adsorption and desorption of the ammonia nitrogen from the sediments were studied through the study of the pollution characteristics of the "high ammonia nitrogen" of the Xianyang River, by studying the ammonia rate of the surface sediments, the potential nitrification rate (PNR) and the adsorption and desorption characteristics of the sediment on the ammonia nitrogen. The migration and transformation process of the ammonia nitrogen in the sediment is revealed. The results show that: (1) The average concentration of TN in the surface layer of the Tianyang River is 24.95mg/ L, which is out of the national surface water type V standard; the average concentration of the surface sediment TN is 292.02 mg/ kg, and the heavy pollution degree of the American EPA sediment evaluation standard is achieved. The main occurrence of nitrogen in surface water is soluble inorganic nitrogen (DIN), in which NH4 +-N is the main pollution component, accounting for 83.6% of DIN. The main occurrence form of the surface sediments is that of the organic nitrogen, which accounts for 89.02% of the TN, while the main occurrence form of the DIN is NH4 +-N, and the proportion is 54.88%. The correlation analysis shows that the nitrogen content and the distribution of nitrogen in the surface water and sediment of the Tianyang River have a certain effect on the nitrogen content and distribution of the different forms. In addition, the form and the content of the nitrogen in the surface water and the sediment can also be influenced by each other. (2) The content of DIN in the water and pore water in the water and pore water of the Yinyang River is mainly NH4 +-N, and the proportion of the DIN is 96.4% and 94.2%, respectively. In the vertical scale, the concentration of NH4 +-N, NO3--N and NO2--N in the overlying water is basically stable with the increasing of the depth, while the fluctuation of the pore water is large, and the NH4 +-N and the NO3--N both have a maximum value in the range of 0-10 cm. In addition, NO2--N exhibits significant volatility in pore water due to its instability. In that space scale, the inorganic nitrogen in the upper and the pore water is still the most serious in the Shijiazhuang section. The diffusion flux and annual load contribution of the inorganic nitrogen in the water-sediment interface of the water-sediment interface of the Yangyang River have obvious spatial difference. For the diffusion flux, in addition to the N02--N in the whole Biyang River as the release of the water from the sediment, the other shows the non-uniform "source" and "foreign exchange" characteristics, indicating that there is a certain nitrogen pollutant release risk in the sediments of the Biyang River. In the field of Shijiazhuang, the diffusion flux of ammonia nitrogen reached. 42.18 mg/ (m2 路 d), and the annual load contribution of the foreign contamination reached 101.62 t/ a, indicating that the section of the river was seriously polluted by ammonia nitrogen. Therefore, at the same time of controlling the external emission, the endogenous load can not be ignored. (3) The average value of the ammonification rate and the potential nitrification rate of the surface sediment of the Youyang River was 4.30. m u.g N/ (g 路 h) and 0.152. m u.g N/ (g 路 h), respectively, which was about 28 times the latter. Compared with other research results, the changes of the ammoniation rate and PNR of the Biyang River are large, and have obvious spatial difference. The adsorption kinetic process of the surface sediment NH4 +-N is in accordance with the parabolic diffusion model and the modified Elovich model, which includes two stages of rapid adsorption and adsorption equilibrium, the former is completed in the first 120 minutes, and then the adsorption equilibrium is gradually achieved. In the low concentration, the isothermal adsorption curves of the NH4 +-N on the surface sediments of the Biyang River meet the Henry model, the fitting degree of the sediment is extremely remarkable, and the adsorption and desorption equilibrium concentration of the sediment is between 0.55 and 26.15 mg/ L, and the background adsorption amount of the sediment is between 8.181 and 402.68 mg/ kg. In addition to S07, the effect of the Langmuir isotherm equilibrium adsorption model is good, and the maximum adsorption capacity of the sediment to the NH4 +-N is between 429.10 and 1162.60 mg/ kg. The Freundlich model could not fit the data. The desorption of NH _ 4 +-N is similar to that of the adsorption kinetics, but it takes 6 h to achieve the adsorption equilibrium. In addition to S07, the rest of the points can be fitted with a first-order kinetic equation. In addition, the variation range of the equilibrium desorption amount of each point is 36.50 to 400.59 mg/ kg. The equilibrium desorption amount of the surface sediments of the Yangyang River has a certain correlation with the TN, NH4 +-N and C/ N values.
【学位授予单位】：中国科学技术大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X52

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