【作者】 赵萱；

【导师】 成杰民；

【作者基本信息】 山东师范大学 ， 自然地理学， 2012， 博士

【摘要】 湖泊富营养化是当今世界各国面临的水污染问题之一。在我国，长江中下游地区浅水湖泊已呈现不同的富营养化状态，其中有机质的富集是湖泊富营养化的重要特征。有机质成分极其复杂，其赋存形态影响着污染物的迁移转化。在富营养化湖泊中重金属是一类重要的污染物，有机质控制着重金属的迁移和生物毒性。有机质来源不同（土壤、河流、湖泊、垃圾滤液），其组成和结构不同，对重金属的结合作用也存在差异。因此，开展对不同生态类型、不同富营养化程度湖泊沉积物中有机质赋存形态及其与重金属相互作用的研究具有重要意义。本研究工作是国家973项目的子课题——富营养化湖泊复合污染机理及生态毒理效应（2008CB418204）。利用紫外-可见光谱、溶解有机碳分析仪、元素分析、傅立叶变换红外、荧光光谱、质子核磁共振等现代分析方法对藻型湖泊（太湖）、草藻型湖泊（南四湖）和草型湖泊（白洋淀）沉积物中不同来源的有机质进行存在形态、结构和组成研究；利用三维荧光光谱和质子核磁共振研究了湖泊沉积物溶解性有机质（DOM）中不同组分（类富里酸、类蛋白）与重金属的配位作用，其主要研究结果如下：1.湖泊富营养化渐进过程的标志就是营养盐的含量变化。同一湖泊不同采样点（不同区域）沉积物中积累的营养物质不同，反映了人类活动和自然因素的变化对湖泊整个生态环境的影响。根据单项污染指数和内梅罗综合指数分别对太湖、南四湖和白洋淀上覆水体进行评价，表明南四湖富营养化最为严重。在高营养盐浓度下，氮、磷营养盐结构对不同生态型湖泊富营养化有重要影响。通过对氮磷比值分析，太湖和白洋淀采样点水体基本均处于磷限制状态。南四湖水体处于氮磷共同限制状态。说明三个湖泊可以通过降低输入含氮磷污染物总量，来缓解富营养化。论文对三个湖泊沉积物中重金属总量、形态进行了分析。采用地积累指数法对重金属总量进行评价，结果表明，三个湖泊沉积物中重金属Cu污染程度为极强度污染，Zn和Pb为无污染或轻污染。三个湖泊中Zn以残渣态和铁锰氧化态为主。Cu以残渣态和有机物-硫化物结合态为主。说明随着沉积物有机质矿化分解及环境条件的改变，沉积物中Cu、Zn等重金属可能发生形态转化，具有较高的潜在生态风险。2.应用物理分组和化学提取方法，研究了三种不同生态类型的湖泊沉积物中总有机质（OM）、轻组有机质（LFOM）和重组有机质（HFOM）、活性有机质（LOM）、溶解性有机质（DOM）的赋存特征。结果表明，湖泊沉积物中LFOM含量均较低（<2％），说明三个湖泊11个沉积物有机质中以难分解的重组有机质为主。三个湖泊沉积物中的对照区轻组有机质和活性有机质含量均大于养殖区和污水排放区，溶解性有机质呈相反趋势。说明对照区中有机质与养殖区和污水排放区相比可能易矿化分解。3.紫外-可见吸收光谱研究结果表明：三个湖泊沉积物中E4/E6比值均大于3.5，说明DOM均为腐殖化程度不高、芳构化程度低、分子量不大。DOM中以富里酸为主，而腐殖酸含量不多。太湖沉积物DOM腐殖化程度、芳构化程度、分子量最低，白洋淀次之，南四湖最高。三个湖泊不同采样区沉积物中DOM紫外光谱特性不同，但总的趋势是对照区沉积物DOM腐殖化程度、芳构化程度、分子量最低。元素分析及红外图谱（FTIR）表明：三个湖泊对照区、养殖区、水生植物区沉积物DOM中含有相似的官能团，主要为：-COOH、胺类、醇、糖类及脂类等。养殖区还含有脂肪类、胺类等特征官能团。水生植物区还含有-NH4+等特征官能团。由于不同湖泊污染来源的不同，因此不同湖泊污水排放区沉积物DOM中含有特征官能团不同。太湖沉积物DOM中含有腈、有机卤化物等；南四湖有炔烃等；白洋淀有脂环、羧酸二聚体等。质子核磁共振（1HNMR）分析结果表明：不同生态类型湖泊、不同来源沉积物DOM中烷基链烃支链相对含量差异较大。但总的趋势是，养殖区和污水排放区沉积物DOM中烷基链烃含量相对较高，支链较长，分支少。对照区烷基链烃含量相对少，支链较短，分支较多。湖泊类型、污染历史、污染来源、污染程度等均为导致沉积物DOM中烷基链烃支链相对含量和结构的差异的主要因素。4.三个湖泊不同来源的沉积物中DOM的荧光光谱特性表明，11个沉积物样品DOM分别为紫外类富里酸、可见类富里酸和类蛋白，其中以类富里酸为主。据荧光指数f450/500推断，太湖和南四湖对照区沉积物中DOM的主要来自生物源。养殖区、污水排放区及水生植物区既有陆源也有生物源。白洋淀对照区沉积物中DOM以陆源输入为主，养殖区以生物源为主，污水排放区和水生植物区主要来自陆源和生物源。同步荧光光谱表明，白洋淀和南四湖沉积物DOM的腐殖质类物质较太湖而言，腐殖化程度高、结构复杂。三维荧光光谱（3DEEM）显示，沉积物DOM含有类富里酸（可见区类富里酸、紫外区类富里酸）和类蛋白（类色氨酸和类酪氨酸）荧光峰。三个湖泊除对照区外，养殖区、污水排放区和水生植物区均表现出极强的类蛋白荧光。荧光强度比值r(B，C)比值在未受污染的对照区为1左右，而受污染严重的水生植物区、养殖区和污水排放区r(B，C)比值在1.5-2.5。r(B，C)可用来指示湖泊受污染程度。三个湖泊采样点r(A，C)值为1.5-3.0，表明沉积物DOM的来源、组成都存在较大差异。5.荧光光谱特征表明，随Cu (Ⅱ)浓度增加，DOM中富里酸或类蛋白荧光强度降低。质子核磁共振谱图证实，Cu (Ⅱ)与DOM中糖类官能团、醌基、羟基或酚基发生配位作用，形成复杂的螯合物。应用修正型Stern-Volmer方程计算的Cu (Ⅱ)配位的荧光基团比例（f）和配位稳定常数(K)显示，DOM中可见光区类富里酸物质对Cu (Ⅱ)配位能力最强，类蛋白物质次之，紫外光区类富里酸物质最弱。溶液pH是影响Cu (Ⅱ)与DOM中富里酸和类蛋白形成配位化合物的稳定性主要因素之一。综上，不同生态型富营养化湖泊，不同来源的沉积物DOM含量、组分及结构性质存在较大差异。可以通过红外光谱、紫外-可见吸收光谱、荧光光谱、核磁共振等现代仪器分析手段，分析其结构组成。根据特征官能团推断污染来源；根据其结构腐殖化程度、分子量大小、支链多少等推断其分解速率，根据荧光光谱参数r(B，C)和类蛋白荧光推断指示湖泊受污染程度；根据其官能团与重金属的螯合稳定性，推断沉积物中重金属释放的可能性。沉积物DOM的光谱特性与沉积物来源、污染程度、分解速率等的定量关系，以及DOM特征官能团与重金属螯合的定量关系是今后研究的方向。更多还原

【Abstract】 Eutrophication is one of serious water pollution problems that occur throughoutthe world. In China, some shallow lakes along the middle and lower reaches of theYangtze River are in the state of eutrophication. Organic matter enrichment is theimportant feature in lake eutrophication. In sediments, organic matter is the key factorto control the environmental behaviors of heavy metal pollutant because complexationbetween heavy metals and organic matter controls heavy metal migration andbiological toxicity. Therefore, the investigation on distribution of organic matter andits complexation with heavy metals in different ecological lakes is important to fightwater pollution.This study is one part of a key project (2008CB418204) financed by ourgovernment. Characters, structures and sources of dissolved organic matter (DOM) inthree different ecology lakes (Taihu Lake, Nansihu Lake and Baiyangdian Lake) wereanalyzed, respectively, using UV spectroscopy, elemental analysis, FTIR,1HNMRand fluorescence spectra. The main findings are as following:1.The water quality is worse than that required by Grade V in Taihu Lake,Nansihu Lake and Baiyangdian Lake. The concentrations of total nitrogen (TN) andtotal phosphorus (TP) are high in water and sediment in Nansihu Lake. This resultshows that it is important to control internal pollution sources. Under higher nutrientconcentration conditions, the mass ratio of nitrogen to phosphorus (N/P) impacts onlake eutrophication. Phosphorus is a limited factor of the eutrophication features inTaihu Lake and Baiyangdian Lake. Nitrogen and phosphorus are limited factor inNansihu Lake. Some measures should be carried out to reduce nitrogen andphosphorus pollutants, which could ease the eutrophic process in Taihu Lake,Nansihu Lake and Baiyangdian Lake. In addition, sedimentary heavy metal pollutionwas also studied through Tessie extraction procedure. The index of geo-accumulation(Igeo) was applied to evaluate the heavy metal pollution in the sediment. Our results show that Cu pollution is serious in the Taihu Lake, in Nansihu Lake and BaiyangdianLake. Zn mainly exists in residual fraction and the iron and manganese oxidationstate fraction ranks the second. Cu mainly exists in residual fraction and the organicthe sulfide phase fraction ranks the second. The results also reveal that Cu and Zn areeasily mobile and could bring ecological risk to the water ecological system.Anthropogenic activities contributed to potential sources of heavy metals.2.Distribution of total organic matter (OM), light fraction organic matter(LFOM),heavy fraction organic matter(HFOM)，labile organic matter(LOM) and DOM in thesediments from three different shallow lakes (Taihu Lake, Nansihu Lake andBaiyangdian Lake ) were investigated by using physical separation methods. Theresults show that the light fraction organic matter (LFOM) is significantly low in allthe sediments. Heavy fraction organic matter (HFOM) is the dominant class amongthe organic matter compositions in Taihu Lake, Nansihu Lake and Baiyangdian Lakesediments. These results demonstrate that the persistent organic compounds accountfor most of the organic matters, and that light fraction organic matter was completelydecomposed.3.Different fractions of DOM have different origin. The hydrogen/carbon andoxygen/carbon ratios decrease from sanitary area, aquatic area, culture area to dirtywater area. These results suggest that the less the ratio, less the polarity, the morestability. The analyses of FTIR and1HNMR also show that DOM of different sourcehas different structural characterization. DOM in culture area and in dirty water iscomposed of the aromatic carbon, aliphatic amines, carboxylic acid dimmers andalkyl chain hydrocarbon material.4.DOM in Taihu Lake, Nansihu Lake and Baiyangdian Lake sediments were alsoinvestigated by using fluorescence spectroscopy. Fluorescence index (f450/500) could beused to distinguish sources. (f450/500) values ranged 1.4-1.9 in Taihu Lake, NansihuLake and Baiyangdian Lake sediments. This result indicated biology sources as wellas land sources of sediments DOM. Fluorescence finger print technique was used tocharacterize dissolved organic matter (DOM) in sediments from different sources.Two types of DOM fluorescence signals were observed in sediments: humic-like fluorescence and protein-like fluorescence. The intensities of both of protein-likefluorescence distinctly increase in culture area and in dirty water area. The values ofr(B，C) is 1 in sanitary area. The values of r(B，C) is 1.5-2.5 in culture zone and dirtywater area, revealing that this index is a indicator degree of lake contamination.Fluorescence finger print technique is potential tool to determine the sources of DOMin polluted lakes.5.Fluorescence spectrum technique has advantages of high sensitivity, andquick-and-easy detection and has widely applied to characterize the dissolved organicmatter (DOM). For better understanding the fluorescence characteristics of DOM inBaiyangdian Lake of China, fluorescence emission spectroscopy andthree-dimensional excitation emission matrix fluorescence spectroscopy (3DEEM)were used. Fluorescence quenching titration and1H NMR were used to investigate theinteraction between Cu (Ⅱ) and DOM. The1H NMR results show that DOM inBaiyangdian Lake is mainly composed of large amount of carbohydrate. Influorescence spectra obtained in our study, two fulvic acid-like fluorescence peaks(peak A and peak C) and protein-like (peakB) were observed. Compared with visiblefulvic-like, protein-like fluorescence intensity is high. The intensity for individualpeak A, B and C decreases as concentrations of Cu (Ⅱ) increase. DOM-Cu (Ⅱ)complexation constants and1H NMR suggest that the fluorescent groups interactmore strongly with Cu (Ⅱ) .更多还原