滇池底泥重金属释放机理分析及影响因素研究

【作者】 陈桂荣；

【导师】 曾向东；

【作者基本信息】 昆明理工大学 ， 环境工程， 2010， 硕士

【摘要】 本论文首先通过滇池底泥中基础数据的研究,得到滇池底泥的污染特点,并主要结合潜在生态危害指数评价法及地质累积指数法比较有效地综合评价现代滇池底泥的污染程度；其次,利用改进的BCR分级提取方法分级提取滇池底泥中重金属存在的4种形态,并通过不同形态的分析来解释重金属释放的原理；接着,采用滇池底泥提取腐殖酸(HA),实验中通过加入不同浓度的HA溶液,分析HA对于重金属释放的影响；然后,采用雷磁数据采集软件,使用类似于络合滴定的方法,通过铜离子选择性电极测定溶液中铜离子的电导率来分析铜离子和HA之间的相互作用机理；最后,使用了与HA与铜离子络合相同的方法,简便快捷地得到滇池底泥对于Cu的络合数据。研究结果表明：(1)滇池底泥重金属污染依照潜在生态污染评价法计算,可以看出滇池底泥中重金属对于环境的潜在污染以Cd为最重,最轻的为Zn,并且北部比南部更易发生底泥重金属的二次污染。滇池底泥重金属污染按照地质累积指数方法计算,可以看出,Pb和Cd的污染比较严重。Cu与Zn的污染较轻。结合两种方法,可以得出,滇池底泥中,Cd是主要的污染问题,Cu、Zn和Pb的污染对于滇池的影响较小。(2)从滇池底泥中重金属BCR形态分布可以看出,滇池底泥从北至南,有效态(除残渣态以外的其他形态之和)逐渐减少,残渣态逐渐增加。有效态是在底泥中起到主要作用的部分,残渣态可以比较稳定的存在于底泥中,而有效态可以比较容易在环境中发生物理、化学、生物等作用。(3)实验研究表明,HA浓度的变化对于Pb的释放影响最大,滇池底泥中有机质含量较高,这种外在条件,有利于滇池底泥中Pb的释放。Cd的污染是滇池底泥重金属污染的主要问题。结合实验中HA浓度变化对于Cd的释放的影响发现,HA浓度的加大,.加强了底泥中Cd的释放能力,但从北至南,Cd的释放率降低,可能与底泥的.特性、采用的HA的性质有关。(4)HA的浓度变化对于重金属存在一定的影响。HA浓度增加,重金属释放量增加。同时,HA的浓度变化对于重金属释放的影响也根据研究地点的不同而不尽相同。(5)铜离子溶液与不同浓度HA溶液进行络合时,随着HA浓度增加,会使得铜离子的络合量增加,铜离子会稳定地与HA螯合。底泥与铜离子的络合实验中,有机质含量较高的草海中心铜离子的络合量最大,说明底泥中有机质含量越高,重金属的释放作用就越小。上述研究结果初步反映了滇池底泥中Cu、Zn、Pb、Cd等重金属的空间分布和含量分布状况,可为评估滇池底泥重金属污染提供依据；同时,以滇池底泥实际样品为对象,通过实验室条件实验,研究探讨了底泥中重金属释放的机理及主要影响因素,可以为治理滇池底泥重金属污染提供依据。更多还原

【Abstract】 In this paper, Firstly, through the basic data research of the sediment from Dianchi Lake, the pollution characteristics were presented. Mainly with the potential ecological risk indices method and geological cumulative index method, the sediment pollution in current Dianchi Lake was effectively assessed. Secondly, using improved BCR extraction method, four different forms of heavy metals in sediment from Dianchi Lake was extracted and the results can be used to analyze the principles of the release of heavy metals and then the humic acid was extracted (HA) from the sediment of Dianchi Lake. Through adding different concentrations of HA solutions, the impact of HA on the release of heavy metals was analyze. Then, with the use of ray magnetic data acquisition software and the similar method of complexometric titration, combined with the conductivity determination of copper ions in the solution by the copper ion selective electrode, the mechanism of copper ions and HA was analyzed. Finally, using the same method of HA and copper ions, it is easy to get the Cu complexometric data in the sediment from Dianchi Lake.Research results show that:(1) According to the potential ecological pollution evaluation method it could be concluded that Cd was the most serious pollution source while Zn was lightest in the terms of the potential impact of heavy metals in the sediment from the Dianchi Lake on the environment. In the north it was easier to be secondary pollution of heavy metals in the sediment than that in the south. With the geological cumulative index method it was presented that the pollution of Pb and Cd was more serious than Cu and Zn. Combining the two methods it could draw, Cd was the main pollution problem in the sediment from Dianchi Lake while Cu, Zn and Pb pollution was lighter.(2) With the BCR distribution of heavy metals in the sediment from Dianchi Lake, it indicated that the effective form (the other froms except the residual form) decreased from north to south. On the contrary, the residual state gradually increased. The effective form was the main role played in the sediment, which was easy to come about the physical, chemical and biological reaction. And the residue state was stabilized in the sediment. (3) According to the experiment results, it showed that the influence of the changes of HA concentrations on the Pb release was greatest and the content of organic matter in the sediment was high, which were helpful to the Pb release. It was the main problem of Cd pollution in the sediment. Combining the influence of the changes of HA concentrations on the Cd release in the experiments, it indicated that with the increasing concentrations the ability of Cd release was increased. But from north to south the rate of Cd release reduced, which was maybe affected by the properties of sediment and the nature of the HA adopted.(4) The changes of HA concentrations could have a certain influence on the heavy metals. with the increasing concentrations of HA, the release of heavy metals also increased. At the same time, the influence of the changes of HA concentrations on the release of heavy metals varied with the different research points.(5) During the complexation of copper ions and HA of different concentrations, with the increasing concentrations of HA, the complexation quantity of copper ions would increase and the copper ions would be chelating with HA. In the complexation experiments of the sediment and copper ions the complexation quantity was highest in the Caohai center with the high organic matter content, which indicated that with the higher organic matter content the release of heavy metals was lower.With the research results, the space distribution and content distribution of the heavy metals such as Cu Pb Zn Cd in the sediment from the Dianchi Lake was presented, which were served as basis for the evaluation of heavy metal pollution in the sediment from the Dianchi Lake. Meanwhile with the combination of the actual samples of the sediment from the Dianchi Lake and the experiments in the laboratory, the mechanism of the release of heavy metals and the main influence factors were discussed, helpful for the treatment of heavy metal pollution in the sediment from the Dianchi Lake.更多还原