【作者】 米娟；

【导师】 潘学军；

【作者基本信息】 昆明理工大学 ， 环境工程， 2011， 硕士

【摘要】 氮营养盐是湖泊生态系统重要的营养元素之一,而且是湖泊富营养化过程中的关键因素,在外源污染得到控制的情况下,内源营养物质的释放将使水体中的氮保持较高浓度,对藻类及其他水生生物的生长具有重要的意义。本文以我国典型的富营养化城市浅水湖泊滇池为研究对象,研究了滇池不同区域水体、表层沉积物间隙水中氮营养盐的形态组成与含量,并采用逐级分离浸取的方法分析滇池表层沉积物中不同形态的氮的赋存形态特征,继而阐明滇池沉积物—水界面中各种形态氮的时空分布特征、变化规律和区域差异及其在氮循环中的作用,为滇池富营养化的治理提供参考依据。本论文的主要研究结果和结论如下：(1)滇池草海地区水体及表层沉积物间隙水中氮的质量浓度较外海高,同时外海地区氮的质量浓度分布以西北部最高,表层沉积物不同形态可转化态氮的含量也以西北部最高。(2)氮浓度在滇池表层、中层和上覆水中分布无明显差异,说明滇池水体运动剧烈、混合充分,而外海表层沉积物间隙水NH4+-N、TN浓度分别为上覆水平均浓度的14倍和6倍,NH4+-N、TN在湖水与表层沉积物间隙水间形成明显的浓度梯度,N03--N则没有呈现同样的浓度分布差异。同时氮在表层沉积物间隙水中主要以NH4’-N的形式存在,呈现出表层沉积物间隙水中氮以NH4’-N为主向上层水体释放的趋势,滇池存在内源释放导致滇池富营养化状态持续的潜在威胁。(3)自然粒度状态下,滇池表层沉积物中可转化态氮的含量比其他水域研究数据高很多,全湖平均值为1825.45gg/g,平均占总氮量的44.79%,由内源释放导致滇池富营养化状况持续的可能性更大。其中以SOEF-N的含量最高(733.68μg/g), IEF-N次之(501.76μg/g), SAEF-N含量最低(197.93μg/g) WAEF-N的含量(392.09μg/g)介于IEF-N和SAEF-N之间,因此SOEF-N是可转化态氮的绝对优势形态,IEF-N是可转化无机氮的绝对优势形态。(4)在可转化态氮都能参与循环的情况下,不同形态氮对循环的绝对贡献率大小为：SOEF-N(40.19%)>IEF-N(27.49%)>WAEF-N(21.48%)>S4EF-N (10.84%)。与其他水域比较,SOEF-N在滇池的绝对贡献率较低。(5)实验结果表明滇池表层沉积物间隙水中氮浓度与湖泊水体氮营养盐浓度的相互影响明显,同时滇池表层沉积物中所有形态的可转化态氮也与滇池上覆水及表层沉积物间隙水中的氮营养盐也呈现一定程度的相关性,而且IEF-N与它们都有一定的正相关关系,说明滇池表层沉积物及其间隙水中的不同形态氮与滇池整体湖泊氮循环过程密切相关。更多还原

【Abstract】 Nitrogen nutrient is one of the important nutrient elements of the lake ecosystem, and is the key factor in the process of Lake eutrophication. If outer-originated pollution can be controlled, the release of internal nutrient will keep relatively high concentration of nitrogen in the water, which plays an essential role in the algal and other aquatic organisms growth.This paper selected the typical eutrophication urban shallow lake-Dianchi Lake as the research object, studying the forms of nitrogen nutrients and concentrations in the lake water, the pore water of surface sediments in different regions of Dianchi Lake, and characteristics of different forms of nitrogen in the surface sediments of Dianchi Lake were analyzed by chemical sequential extraction methods.Then explained the spatial and temporal distributions, variation trends, regional diversities and the functions in recycling of nitrogen with different forms in sediment-water interface, in order to providing references for the preventing and controlling eutrophication of the lake water.The main research results and conclusions are as follows:(1) The distributions of N in Caohai for lake water and the pore water of surface sediments, which were higher than that in Waihai, and the highest concentration area of N was northwest area in Waihai.So it is with different forms of TF-N in surface sediments.(2) There was no discrepancy between the distributions of N in surface, middle and overlaying water, it showed that lake water was moved dramatically and fixed completely. But the concentrations of NH4+-N,TN in pore water of surface sediments were fourteen times and six times higher than the concentrations in overlaying water of Waihai respectively, and they formed a remarkable concentration gradient.However the concentrations of NO3--N in pore water of surface sediments were almost the same with those in overlaying water of Waihai. In the pore water of surface sediments, N was mainly consisted of NH4+-N, and the concentrations of which was much higher than that of NO3--N, thus there was the trend of N release from sediment to watef, and it was a potential threat of eutrophication in Dianchi Lake.(3) The content of TF-N in natural grain size surface sediments of Dianchi Lake was much higher than other waters. On average, the content of TF-N was 1825.45μg/g, and TF-N accounted for 44.79% of TN. Consequently, the internal pollution sources were more likely to maintain the persistent eutrophic status in Dianchi Lake. The SOEF-N contents (733.68μg/g) were the highest among the four forms of nitrogen; and the contents of IEF-N (501.76μg/g) were lower than those of SOEF-N, while were the highest among the inorganic nitrogen; the contents of WAEF-N (392.09μg/g) were lower than those of IEF-N and higher than those of SAEF-N(197.93μg/g).(4)Analysis of TF-N and their functions in sediment-water exchange showed that absolute contributions of different nitrogen forms in nitrogen recycling were consistent with their contents in sediment, which had the sequence SOEF-N(40.19%)>IEF-N(27.49%)>WAEF-N(21.48%)>SAEF-N(10.84%). Compared with other waters, the absolute contributions of SOEF-N were lower.(5)The results showed that there was remarkable relativity between the concentrations of N in pore water of surface sediments and the water body. Meanwhile, the analysis on correlation indicated that very close correlations existed between the distributing characteristics of TF-N in Surface sediments and that of different forms nitrogen in overlaying water and the pore water from the surface sediments. Especially, IEF-N was highly and positively correlated to them. There were the results that the different forms of nitrogen in sediment-water interface and the nitrogen cycling in Dianchi Lake were found interaction.更多还原