南四湖溶解性有機(jī)質(zhì)對Pb和As遷移轉(zhuǎn)化的影響
發(fā)布時間：2018-10-25 08:43
【摘要】：溶解性有機(jī)質(zhì)(Dissolved organic matter,DOM)是控制天然水生態(tài)系統(tǒng)中重金屬的生物地球化學(xué)行為和毒性的重要因素之一。近年來,南四湖重金屬累積有明顯的上升趨勢,上級湖的支流污染及人類活動的影響,導(dǎo)致南四湖也有一定程度的富營養(yǎng)化問題。在野外調(diào)查的基礎(chǔ)上,完成了全湖30個點(diǎn)位的采樣工作,所采的表層沉積物和上覆水用于室內(nèi)模擬試驗(yàn),系統(tǒng)探討了DOM對Pb和As的形態(tài)及遷移轉(zhuǎn)化的影響。得到了如下結(jié)論:(1)表層沉積物的理化性質(zhì)測試表明,南四湖Pb、As、Hg、Cd這四種重金屬富集程度較為明顯,南四湖整體處于中等的潛在生態(tài)風(fēng)險等級。通過對重金屬相關(guān)性分析表明,Cr、Cu、Zn、Ni這4類元素均屬于自然沉降為主,受人為擾動較小。As、Hg、Cd、Pb受人為擾動較大。南四湖上級湖區(qū)重金屬總體污染水平比下級湖嚴(yán)重。(2)利用南四湖原狀水樣,模擬光降解和微生物降解兩種方式作用下,溶解性有機(jī)質(zhì)(DOM)的降解過程和不同的降解特性表明,DOM的去除率和氨氮的濃度以及活性磷酸鹽(SRP)的濃度存在顯著正相關(guān)關(guān)系。水體DOM的三維熒光光譜圖中出現(xiàn)了4個明顯的熒光峰,分別為類蛋白(B)、(D)峰,紫外富里酸(A)峰及可見光富里酸(C)峰。(3)吸附解析實(shí)驗(yàn)表明湖泊沉積物中DOM有利于重金屬在固液兩相中的分配,DOM與Pb結(jié)合特性要優(yōu)于As。DOM與自由態(tài)的Pb的反應(yīng)主要發(fā)生在兩個階段:首先是發(fā)生了離子交換,之后Pb與分子量較大的DOM發(fā)生化合反應(yīng)形成沉淀,隨著沉淀的產(chǎn)生,溶液中Pb離子的濃度減少。(4)平衡滲透實(shí)驗(yàn)表明,南陽湖表層沉積物DOM的分子量整體上大于微山湖。南陽湖DOM的分子量主要集中在3.5~5.0ku的范圍內(nèi);微山湖DOM的分子量主要集中在0.5~3.5ku范圍內(nèi)。對于Pb結(jié)合能力上南四湖不同區(qū)域沒有明顯的差異;而對于As的結(jié)合能力上,南陽湖高于微山湖。結(jié)合容量的計(jì)算結(jié)果表明,As對有機(jī)質(zhì)的聚合能力高于Pb,Pb易與分子量≤2.0ku的DOM結(jié)合,As易與分子量在2.0~3.5ku的DOM結(jié)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，
本文編號：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，
本文編號：2293196
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