【作者】 樊庆云；

【导师】 何江；

【作者基本信息】 内蒙古大学 ， 生态学， 2008， 博士

【摘要】 天然水体是受重金属污染的主要生态系统之一,受重金属污染的水体沉积物被喻为“化学定时炸弹”,沉积物是水环境重金属污染的指示剂。流域的经济开发是当今发展的趋势,环境问题已成为“自然-经济-社会”这一复合生态系统能否持续发展的关键。城市化和工业化进程加剧了人类生存环境的危机,几乎所有的河流、湖泊和海洋都遭受了不同程度的污染,世界各国均把重金属列为水质监测和评价的重要指标。包头市是黄河流域沿岸典型的重工业城市,在城市工业废水对黄河水体重金属污染方面具有典型性和代表性。已有的研究表明,形态分析是生物可给性的基础,也是判识沉积物中重金属污染潜在危害的前提。自然水体是一个含有多种离子的复杂体系,开展符合自然水体实际情况的多离子共存体系中重金属在天然沉积物上竞争吸附动力学和竞争吸附对重金属形态转化影响的研究对揭示水体重金属污染的机理更具实际意义。采用微生态系统暴露实验和AVS法,结合孔隙水中重金属浓度,综合判断黄河水体重金属的生物有效性则有助于研究问题的系统解决。从黄河水体重金属污染的机理和效应着手,探讨重金属在黄河水体中的迁移转化规律,揭示黄河沉积物重金属形态分布与生物有效性及毒性的关系,预测黄河沉积物中重金属的生物有效性和毒性,判识黄河沉积物中重金属污染的潜在危害,不仅可为黄河包头段水体重金属的污染防治提供对策和科学依据,同时也可为保护黄河水质和城市工业废水对河流重金属污染的研究提供借鉴。本研究以环境地球化学、生物地球化学、污染生态学及现代沉积学的理论和方法为指导,以重金属的地球化学特性及其生物有效性为主线,分别于2004年和2005年按枯、丰、平3个水期系统采集了黄河包头段干支流等9个断面的上覆水、孔隙水、悬浮物及沉积物柱芯等样品,捕获了黄河包头段天然鱼样品,共获得17287个实验测试数据。深入探讨了符合黄河实际的多离子体系中重金属的竞争吸附及其迁移转化机制、水体重金属的污染特征、重金属在水-沉积物.鱼微生态系统中的响应关系以及野生经济鱼类重金属的富集规律。首次开展了承纳大量城市工业废水的黄河包头段鱼微生态系统暴露实验研究,为重金属生物有效性、生物地球化学循环及生态风险评价积累了大量基础数据。此外,鉴于南海湖与黄河的沉积同源性和继承性,开展了南海湖水体沉积物中重金属的环境地球化学特征研究。本研究取得如下主要成果和进展。1.首次开展了黄河包头段鱼微生态系统暴露实验,判识了水-沉积物系统与鱼体中重金属的响应关系,构建了可判识水环境中重金属形态与鱼组织器官中有毒金属关系的回归模型,为重金属污染的生物监测提供了新的可供借鉴的有效方法。2.首次综合评价了黄河包头段9种经济鱼类的综合污染程度,得出了青鳞子＞鲫鱼＞花鱼骨＞团头鲂＞棒花鱼＞黄河鲤＞赤眼鳟＞鲈塘鳢＞蛇鮈的重金属污染程度序列。创新了鱼体沉积物分形态富集系数概念,拓展了污染物生物富集机理研究的思路。3.发现了枯水期黄河沉积物为重金属的汇,丰水期为源的特异性规律。采用沉积物重金属质量基准,判识了黄河沉积物的潜在风险性。研究揭示,包头市工业废水排放对黄河干流水体重金属的污染迭加有重要贡献。4.实验得出了Pb²⁺＞Cu²⁺＞＞Zn²⁺＞Cd²⁺的竞争吸附序列以及Cd＞Zn＞＞Cu＞Pb的释放能力序列。该项研究成果对揭示水-沉积物系统中重金属的迁移转化机制具有重要意义。5.研究证实,南海湖与黄河具有明显的沉积同源性和继承性。表层沉积物间隙水中Cu和Cd,特别是Cu有从间隙水向上覆水扩散迁移的显著特性。沉积物间隙水在重金属由沉积物向上覆水迁移过程中起重要的桥梁通道作用。与一般淡水湖泊不同,南海湖沉积物中AVS的垂向分布出现极大值下移及多个极大值现象。AVS是控制南海湖水体中重金属沉淀的关键因子,有机络合剂是促进Cu向水相扩散迁移的主导因子。6.引入了重金属形态分布的空间效应的概念,利用空间效应理论较好地阐释了南海湖水质Cu污染及不同水期黄河沉积物重金属源/汇功能转化的机制。更多还原

【Abstract】 Natural water is one of the main ecosystems contaminated by heavy metal. Since sediments of the natural water contaminated by heavy metal are usually called as "Chemical Time Bomb", the sediments are chosen as an indicator of heavy metal contamination. With the developing economy of drainage basin, environmental problem becomes a key factor restricting the sustainable development of Nature-Economy-Society system. The civilization and industrialization have destroyed the natural conditions around human, as nearly all of the rivers, lakes and sea were polluted with heavy meals. Many countries all over the world regulate the heavy metal contents as important indicator for water quality monitoring and assessment.Baotou city is a typical heavy industrialized city on the drainage basin of the Yellow River. Therefore, the Baotou section of The Yellow River is a typical and representative section for studying the contribution of urban industrial waste water on heavy metal pollution of the Yellow River.Speciation analysis is a basis for bioavailability research, it is used to identify potential hazards of heavy metals in sediments. Natural water is a complex multi-ion system. Research about competitive adsorption dynamics of heavy metals onto natural sediments in multi-ion solution （simulate the natural conditions） and about impacts of competitive adsorption on transformation of heavy metal species are of great importance for revealing heavy metal pollution mechanism. Exposure experiments of micro-ecosystem, study about acid-volatile sulfide and heavy metal concentrations in pore water are of propitious to systematically study the heavy metal pollution characteristics.Based on the mechanism and effect of heavy metal pollution in the Yellow River, the transition and transformation characteristics of heavy metals in the Yellow River are discussed; the relation between speciation, bioavailability and toxicity of heavy metal in sediments are revealed and identified; the potential hazards of heavy metal contamination in the sediments are evaluated. The paper could provide strategy and scientific basis for the prevention and cure of heavy metal contamination in the Baotou section of the Yellow River, and could also provide reference for the study about water quality protection of the Yellow River and study about impacts of urban industrial inputs on heavy metal pollution in rivers.Based on the theories of Environmental Geochemistry, Biogeochemistry, Pollution Ecology, and Modern Sedimentology, this work is focused on geochemical characteristics and bioavailability of heavy metals. The overlying water, pore water, suspended particulate matter, sediment core and fish samples are collected at nine sections of the mainstream and the tributaries in low water period, medium water period and high water period in 2004 and 2005. We obtained 17287 data through experimental test. The mechanisms of competitive adsorption and transformation of heavy metals in multi-ion system （simulate the natural conditions of the Yellow River）, the pollution characteristics of heavy metals, the relation of heavy metals in water-sediment-fish micro-ecosystem and the bioaccumulation of heavy metals in fishes are discussed in detail. This is the first research that carries out lots of exposure experiments of fish of the Baotou section of the Yellow River to the urban industrial waste water, and provides large amounts of basic data for bioavailability, biogeochemical cycle and ecological risk assessment of heavy metal. Additionally, according to the consanguinity between the Yellow River and the Nanhai lake, the geochemical characteristics of heavy metals in the sediments of the Nanhai lake are studied. The conclusions are as follows:1. The exposure experiments of micro-ecosystem to fishes is carried out first time by simulating the condition of the Yellow River; the response relation of heavy metals between water-sediment-fish system is identified; the linear model which can identify the relation between heavy metal speciation in water and toxicity in fish organs is established, which maybe provide a new effective methods for the biological monitoring of heavy metal pollution.2. The pollution level of nine Yellow River fishes are assessed first time, it ranked as: Hemiculter leucisclus > Carassius auratus auratus > Hemibarbus maculatus > Megalobrama amblycephala > Abbottina rivularis Basilewsky > Cyprinus carpio >Squaliobarbus curriculus> Perccottus glehni > Saurogobio dabryi. By developing the concept of bioaccumulation factors, the train of thought of the mechanism research about the bioaccumulation is broadened.3. The sediments of the Yellow River function as a sink of heavy metal in low water period, whereas a source in high water period. The sediment quality criteria of heavy metals are used here to study the potential risk of the Yellow River sediments. The study indicates that the industrial inputs from Baotou city have a large contribution on heavy metal enrichment in the mainstream of the Yellow River.4. The competitive adsorption capacities are ranked as: Pb²⁺ > Cu²⁺ >> Zn²⁺ > Cd²⁺ ; whereas the release capacities are ranked as: Cd>Zn?Cu>Pb. This result is of great importance for the research about heavy metal transformation mechanism in water-sediment system.5. The Nanhai lake presents notorious consanguinity with the Yellow River. In pore water of the surface sediments, Cu and Cd （especially Cu） present releasing trends towards overlying water. The pore water functions as a bridge in heavy metal transition process from sediments to overlying water.Different from normal fresh water lakes, the vertical distribution of acid-volatile sulfide of the Nanhai lake shows the maximum downward shifting because of oxidation. The acid-volatile sulfide is the key factor controlling heavy metal precipitation of the Nanhai lake, and the organic agent is the main factor promoting the release of Cu from sediment to water phase.6. The conception of spatial effect of heavy metal speciation distribution is introduced. Furthermore, the Cu pollution of water in the Nanhai lake and the transformation mechanism of sink/source of the sediments in different water periods are well discussed based on the conception of spatial effect.更多还原