南四湖溶解性有机质对Pb和As迁移转化的影响
发布时间：2018-10-25 08:43
【摘要】：溶解性有机质(Dissolved organic matter,DOM)是控制天然水生态系统中重金属的生物地球化学行为和毒性的重要因素之一。近年来,南四湖重金属累积有明显的上升趋势,上级湖的支流污染及人类活动的影响,导致南四湖也有一定程度的富营养化问题。在野外调查的基础上,完成了全湖30个点位的采样工作,所采的表层沉积物和上覆水用于室内模拟试验,系统探讨了DOM对Pb和As的形态及迁移转化的影响。得到了如下结论:(1)表层沉积物的理化性质测试表明,南四湖Pb、As、Hg、Cd这四种重金属富集程度较为明显,南四湖整体处于中等的潜在生态风险等级。通过对重金属相关性分析表明,Cr、Cu、Zn、Ni这4类元素均属于自然沉降为主,受人为扰动较小。As、Hg、Cd、Pb受人为扰动较大。南四湖上级湖区重金属总体污染水平比下级湖严重。(2)利用南四湖原状水样,模拟光降解和微生物降解两种方式作用下,溶解性有机质(DOM)的降解过程和不同的降解特性表明,DOM的去除率和氨氮的浓度以及活性磷酸盐(SRP)的浓度存在显著正相关关系。水体DOM的三维荧光光谱图中出现了4个明显的荧光峰,分别为类蛋白(B)、(D)峰,紫外富里酸(A)峰及可见光富里酸(C)峰。(3)吸附解析实验表明湖泊沉积物中DOM有利于重金属在固液两相中的分配,DOM与Pb结合特性要优于As。DOM与自由态的Pb的反应主要发生在两个阶段:首先是发生了离子交换,之后Pb与分子量较大的DOM发生化合反应形成沉淀,随着沉淀的产生,溶液中Pb离子的浓度减少。(4)平衡渗透实验表明,南阳湖表层沉积物DOM的分子量整体上大于微山湖。南阳湖DOM的分子量主要集中在3.5~5.0ku的范围内;微山湖DOM的分子量主要集中在0.5~3.5ku范围内。对于Pb结合能力上南四湖不同区域没有明显的差异;而对于As的结合能力上,南阳湖高于微山湖。结合容量的计算结果表明,As对有机质的聚合能力高于Pb,Pb易与分子量≤2.0ku的DOM结合,As易与分子量在2.0~3.5ku的DOM结合。
[Abstract]:Dissolved organic matter (Dissolved organic matter,DOM) is one of the important factors to control the biogeochemical behavior and toxicity of heavy metals in natural water ecosystem. In recent years, the accumulation of heavy metals in Nansihu Lake has an obvious upward trend, and the pollution of tributaries and the influence of human activities have led to the eutrophication of Nansihu Lake to a certain extent. On the basis of field investigation, the sampling work of 30 sites in the whole lake was completed. The collected surface sediments and overlying water were used for indoor simulation tests. The effects of DOM on the morphology and migration and transformation of Pb and As were systematically discussed. The main conclusions are as follows: (1) the physical and chemical properties of surface sediments show that the four heavy metals in Nansihu Lake are obviously enriched, and the whole Nansihu Lake is in the middle potential ecological risk grade. According to the correlation analysis of heavy metals, the four elements of Cr,Cu,Zn,Ni belong to the natural sedimentation, but the human disturbance is relatively small, and the As,Hg,Cd,Pb is greatly disturbed. The total pollution level of heavy metals in the upper lakes of Nansihu Lake is more serious than that in the lower lakes. (2) using the raw water samples of Nansihu Lake, the effects of photodegradation and microbial degradation are simulated. The degradation process and different degradation characteristics of dissolved organic matter (DOM) show that there is a significant positive correlation between the removal rate of DOM and the concentration of ammonia nitrogen and the concentration of active phosphate (SRP). There were four obvious fluorescence peaks in the three-dimensional fluorescence spectra of water DOM, which were protein-like (B), (D) peaks. (3) adsorption and analysis experiments show that DOM in lake sediments is favorable to the distribution of heavy metals in solid and liquid phases, and the binding characteristics of DOM and Pb are better than that of As.DOM and free Pb. (3) adsorption and analysis experiments show that DOM in lake sediments is favorable to the distribution of heavy metals in solid and liquid phases, and the binding characteristics of DOM and Pb are superior to those of As.DOM and free Pb. Born in two stages: first, there's an ion exchange, After that, Pb reacted with DOM with high molecular weight to form precipitation. With the precipitation, the concentration of Pb ion in solution decreased. (4) the equilibrium permeation experiment showed that the molecular weight of DOM in the surface sediments of Nanyang Lake was higher than that in Weishan Lake on the whole. The molecular weight of DOM in Nanyang Lake was mainly concentrated in the range of 3.5~5.0ku, and the molecular weight of DOM in Weishan Lake was mainly in the range of 0.5~3.5ku. For Pb binding ability, there is no obvious difference in different regions of Nansihu, but for As, Nanyang Lake is higher than Weishan Lake. The calculation of binding capacity shows that the polymerization ability of As to organic matter is higher than that of Pb,Pb to DOM with molecular weight 鈮，
本文编号：2293196
[Abstract]:Dissolved organic matter (Dissolved organic matter,DOM) is one of the important factors to control the biogeochemical behavior and toxicity of heavy metals in natural water ecosystem. In recent years, the accumulation of heavy metals in Nansihu Lake has an obvious upward trend, and the pollution of tributaries and the influence of human activities have led to the eutrophication of Nansihu Lake to a certain extent. On the basis of field investigation, the sampling work of 30 sites in the whole lake was completed. The collected surface sediments and overlying water were used for indoor simulation tests. The effects of DOM on the morphology and migration and transformation of Pb and As were systematically discussed. The main conclusions are as follows: (1) the physical and chemical properties of surface sediments show that the four heavy metals in Nansihu Lake are obviously enriched, and the whole Nansihu Lake is in the middle potential ecological risk grade. According to the correlation analysis of heavy metals, the four elements of Cr,Cu,Zn,Ni belong to the natural sedimentation, but the human disturbance is relatively small, and the As,Hg,Cd,Pb is greatly disturbed. The total pollution level of heavy metals in the upper lakes of Nansihu Lake is more serious than that in the lower lakes. (2) using the raw water samples of Nansihu Lake, the effects of photodegradation and microbial degradation are simulated. The degradation process and different degradation characteristics of dissolved organic matter (DOM) show that there is a significant positive correlation between the removal rate of DOM and the concentration of ammonia nitrogen and the concentration of active phosphate (SRP). There were four obvious fluorescence peaks in the three-dimensional fluorescence spectra of water DOM, which were protein-like (B), (D) peaks. (3) adsorption and analysis experiments show that DOM in lake sediments is favorable to the distribution of heavy metals in solid and liquid phases, and the binding characteristics of DOM and Pb are better than that of As.DOM and free Pb. (3) adsorption and analysis experiments show that DOM in lake sediments is favorable to the distribution of heavy metals in solid and liquid phases, and the binding characteristics of DOM and Pb are superior to those of As.DOM and free Pb. Born in two stages: first, there's an ion exchange, After that, Pb reacted with DOM with high molecular weight to form precipitation. With the precipitation, the concentration of Pb ion in solution decreased. (4) the equilibrium permeation experiment showed that the molecular weight of DOM in the surface sediments of Nanyang Lake was higher than that in Weishan Lake on the whole. The molecular weight of DOM in Nanyang Lake was mainly concentrated in the range of 3.5~5.0ku, and the molecular weight of DOM in Weishan Lake was mainly in the range of 0.5~3.5ku. For Pb binding ability, there is no obvious difference in different regions of Nansihu, but for As, Nanyang Lake is higher than Weishan Lake. The calculation of binding capacity shows that the polymerization ability of As to organic matter is higher than that of Pb,Pb to DOM with molecular weight 鈮，
本文编号：2293196
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