【作者】 易文利；

【导师】 王国栋； 王圣瑞；

【作者基本信息】 西北农林科技大学 ， 生物物理， 2008， 博士

【摘要】 湖泊富营养化是我国严重的水环境问题之一,磷素过量输入是导致湖泊富营养化的直接原因,而有机质的富集是湖泊富营养化的重要特征。因此湖泊有机质对磷素的分配、磷素在界面间的迁移转化及影响机理的研究就显得尤为重要。本研究是“973”国家重点基础研究发展规划项目“湖泊富营养化过程与蓝藻水华暴发机理研究”(项目编号:2002CB412304)的一部分,主要研究了有机质在浅水湖泊中的分布特征、有机质对沉积物磷素吸附/释放的影响机理及有机质对磷素在沉积物—水界面—沉水植物间迁移转化的影响。主要研究结果如下:(1)应用物理化学方法,研究了长江中下游浅水湖沉积物中总有机质(OM)、活性有机质(LOM)、溶解性有机质(DOM)、轻组(LFOM)、重组有机质(HFOM)、胡敏酸(HA)、富里酸(FA)、胡敏素(HM)的赋存特征。结果表明,长江中下游浅水湖泊11个沉积物的OM含量为9.80~110.04 g/kg,城市湖泊的有机质及组分含量均大于自然湖泊; DOM的紫外-可见吸收光谱中表明浅水湖泊沉积物DOM腐殖化程度较低;同时OM中的LOM、DOM、LFOM、HFOM、HA、FA和HM两两之间呈现显著的正相关性,且均与沉积物总磷(TP)、阳离子代换量(CEC)和粉沙粒(Silt)存在显著正相关关系,与粗沙粒(Sand)、二氧化硅(SiO2)存在显著负相关关系;沉积物腐殖质三种结合形态含量随沉积物污染程度的增加而增大,而松/紧比表现为污染严重的城市湖泊小于自然湖泊。(2)有机质的含量与其自身的特性对沉积物磷的吸附和释放均产生重要影响,经过预处理得到不同有机质含量和不同组分的沉积物样品,研究其对磷的吸附、释放的影响。结果表明:沉积物轻组(LF)的去除并没有影响溶解性磷酸盐(SRP)和溶解性有机磷(DOP)释放动力学曲线的基本趋势,去除LF前后湖泊沉积物释放动力学均符合抛物线扩散方程,LF去除提高了各沉积物磷的释放量、释放速率,同时去LF后,提高了沉积物的pH,促进了磷的释放,主要是通过OH-对沉积物铁/铝结合态磷的阴离子置换和破坏了轻组有机质的羧基(-COOH)及羟基(-OH)和沉积物中的无机物胶体形成的胶结物;沉积物磷的释放与有机质的氨基、羧基、羟基等官能团有关;去除轻组有机质没有影响沉积物对磷的吸附动力学的基本趋势,减弱了沉积物对磷的吸附,降低了沉积物对磷的吸附效率,提高了本底吸附态磷的含量,加剧了沉积物向上覆水释放的趋势,同时去除轻组有机质前后沉积物对磷的吸附等温线符合Freundlich模型;不同有机质含量沉积物中磷素的释放趋势基本一致,只是释放量不同;随着有机质含量的减少,SRP、DTP释放速率和释放量增加,而DOP则降低;同时,不同有机质含量沉积物对磷吸附的动力学和热力学趋势也基本一致,且沉积物对磷的吸附等温线均可以用Langmuir方程和Freundlich方程很拟合。(3)在传统研究的沉积物-水“两相”体系中加入了“植物相”,构建了沉积物-水-沉水植物的“三相”结构模式,全面研究了碳源对沉水植物—水—沉积物界面各形态磷含量及迁移、转化的影响,并重点研究了沉水植物及其各个器官对氮磷吸收的差异和其生理指标的变化,结果表明:外加碳源促进了沉积物中磷素的释放,增加了上覆水TP、DTP、SRP和DOP的含量;沉水植物狐尾藻的不同器官对氮、磷素吸收的能力存在差异,随培养时间的延长,总氮和总磷在叶片中的分配量逐渐减少,而在根系和茎杆中的分配量逐渐增加;同时,外加碳源,对植物的生长造成了一定的胁迫。(4)室内模拟了有机质腐解过程对沉积物—水界面磷素迁移和沉水植物生长的影响,结果表明:外加有机质增加了底泥营养盐浓度(主要是提高了NaOH-P和有机磷含量),对沉积物有显著污染作用,同时也影响了狐尾藻对总磷的吸收与积累;有机质腐解过程中引起水质指标变化,尤其是降低溶解氧、pH等是沉水植物受到胁迫的主要原因;在本研究条件下,有机质的腐解过程,对沉水植物的生长有两面性,低含量有机质的加入,在一定程度上可促进植株生长,而高含量的有机质加入,对沉水植物的生长有明显的胁迫。更多还原

【Abstract】 Lake eutrophication is one of the most important environmental problems in our country. When the input of contamination was cut off, nutrient release from sediments would cause the lake eutrophication. So sediment is the keystone in the treatment of lake eutrophication. And phosphorus is one of the important effect factors inducing the lake eutrophication, therefore, researches about distribution and transform of phosphorus among shallow lakes, adsorption and release between the sediment, the overlying water and hydrophytes, and the main effect factors are of most significance. What has been done in this paper is one part of a key project financed by the government of our country, and the serial number of this project is 2002CB412304. Distribution characteristic of OM and the effect mechanism of OM on phosphorus adsorption/release of sediment in shallow lakes were investigated, especially discussed the effect of OM on phosphorus distribution character in sediment-water-plant system. The main findings are as following:(1) Distribution of total organic matters (OM), Labile organic matter (LOM), dissolved organic matter (DOM), Light fraction organic matter(LFOM), Heavy fraction organic matter(HFOM), Humic(HA), Fulvic(FA),and Humin(HM) on the sediments from shallow lakes in the middle and lower reaches of the Yangtze River were investigated by using physical chemistry methods .The result showed: Contents of OM of 11lake sediment samples of the studied region were 9.80-110.04 g/kg, In the present study that city lake sediments>natural lake sediments of the composition and total content of organic matter in the sediments of shallow lakes and lower reaches of Yangtze River; The DOM UV-Vis absorbance, Showing the humification level of DOM is relatively low; LOM, DOM, LFOM, HFOM, HA, FA and HM have remarkable positive correlation between them, respectively. There is remarkable positive correlation with the contents of TP, CEC and silt of the studied samples, respectively, but have remarkable negative correlation with the contents of their sand,SiO2. The contents of three combined status are increasing with the polluted level, but the city lake sediments < natural lake sediments of the loosly and firmly ratio.(2) The content of OM and its different components had important effects on P adsorption and release, so the effect mechanism of OM on P adsorption and release was investigated.The result showed: LF of the different trophic sediments from the Yuehu Lake, Wuli Lake and Gonghu Lake were removed by physical density (NaI) separation;The removal of LF shows a little effect on the P release kinetics from lake sediments;The data of P release rates fitted to the parabolic diffusion equation; The removal of LF increases the amount of the P released and its release rate, The removing of LF from the sediments accelerated the P release mainly relate to the two reasons. One is to replace phosphate ion existing in a form of Fe/Al-bounded phosphorus in the sediment with OH- through enhance pH, and the other is to destroyed colloid of LF with sediment of H-bounds on carbonyl. So the processes of P release from lake sediment relates to its amido, carboxyl, and hydroxide of organic matter;The removal of LF shows a little effect on the P sorption kinetics from lake sediments;Reduced the efficiency of phosphate sorption on the lake sediment, improved the content of EPC0, accelerated the release of phosphate. ,and the data of P release rates fitted to the Freundlich equation; The phosphate release kinetic did not change within the sediment samples of different OM contents, but the amount of phosphate release varied. With OM decreasing in the sediments, SRP and DTP release capacity become increasing, DOP release capacity become decreasing,. At the same time, phosphate adsorption kinetic and thermodynamics trends both did no change with the pretreatment, the phosphate adsorption thermodynamics trends fitted to the Freundlich and Langmuir equation, the adsorption capacities were decreasing with the content of OM decreasing.(3) Inducted hydrophytes to the traditional double-phase structure model, the effect of glucose on phosphorus distribution character was researched in the three-phase structure model, especially the effect of physiological and its organizations on phosphorus and nitrogen adsorption. The result showed:Addition of glucose, the release capacity of phosphorus from sediments were improved, and increase the contents of TP, DTP, SRP and SRP in overlying water; With the training, the accumulation content of total N and P in the leaves gradually reduced, and in the roots and stems the distribution of gradually increased.This study conditions, glucose restrain the growth of submerged plants at the beginning of experiment, but promot the the growth in the latter time.(4) The physiological effects of different macrophyte litter content on the decomposition were inverstigated in a laboratory experiment.The addition of macrophyte litter to the sediment resulted in a higher nutrient content(especially enhance the content of NaOH-P and organic phosphorus), aggravated the pullution of sediment, and the absorption and accumulation content of Myriophyllum spicatum L was affected; The changeof water quality in the process of macrophyte litter decomposing, especially the decreases of Do and pH to the normal growth of Myriophyllum spicatum L. The results indicated that the moderate concentration of macrophyte litter couls accelerate the normal growth of Myriophyllum spicatum L, but the rasied concentrations of litter could be a stress to plants and influenced the normal growth of Myriophyllum spicatum L.更多还原