【作者】 龚玲兰；

【导师】 奚小双； 孔华；

【作者基本信息】 中南大学 ， 矿产普查与勘探， 2011， 博士

【摘要】 汾河流域是山西省工业集中、农业发达的地区,在山西省的经济发展中具有举足轻重的作用。近年来降雨偏少,且季节性明显,河流的生态功能已大为衰退。随着直接或间接排入汾河的污染物越来越多,由此带来的环境污染与事故日渐突出,严重威胁着人类健康。其中重金属因其自身的非降解性和通过食物链富集、毒性放大的特性,其污染问题备受关注。本文主要研究内容如下：对汾河进行了系统的水体多介质(水、悬浮物、底泥)地球化学测量及河漫滩剖面测量；着重对八种重金属元素Hg、Cd、Pb、As、Cr、Cu、Ni、Zn进行了生态地球化学评价。尝试测定了汾河河漫滩沉积物的210Pb丰度。估算了汾河沉积物的沉积速率和重金属沉积通量；大致推导了重金属的主要污染时期。对重金属含量高的样品进行重金属形态分析,探讨了其生态危险性,并对重金属元素的来源及其迁移转化进行了探讨。论文主要成果与认识如下：(1)、汾河重金属在悬浮物中含量最低,在水中含量较高,在底泥中最高。从太原到河津,汾河重金属含量总体上趋于增加。黄河过滤水中重金属元素含量均低于河津过滤水中含量,黄河临猗重金属高于黄河禹门口。汾河枯水期悬浮物中重金属元素浓度均低于丰水期。反映在丰水季节泥沙夹带了大量的污染组分进入河流。汾河底泥的污染程度高于黄河。总之,汾河水体对黄河有明显的重金属输入污染。(2)、汾河污染物主要在太原盆地和临汾盆地沉积物中,太原盆地沉积物重金属峰值集中在12～66厘米,临汾盆地重金属富集峰值的深度大致在88～100厘米左右。推测重金属累积通量高值段出现在20世纪80年代初以后时期,为重金属人为负荷量输入高峰期。重金属浓度与其沉积通量分布呈正相关性,与南方河流不同。太原盆地和临汾盆地是汾河的纳污库,将来有可能是黄河新的污染源。(3)、采用目前国内外主要的评价方法,全面、客观评价了汾河水体及沉积物中重金属元素的污染程度。综合各种评价方法,认为汾河水体已受到重金属污染：Hg、Cr、Cd在河津为国家标准(GB3838-2002)V类水,六个监测断面上Hg的含量均属国家标准V类水。汾河水体中Pb、As、Zn、Cu和Ni含量较低,污染较轻。汾河河漫滩沉积物主要污染也是汞镉污染,其他重金属污染相对较轻。六个沉积柱重金属污染程度递降的顺序为,MHH1420副>MHH1419> MHH1418> MHH1421> MHH1414> MHH1417,除MHH1418(介休)无重警样,其他沉积柱都出现了重金属污染严重现象,即生态系统服务功能严重退化,生态环境受到较大破坏,生态问题较大,生态灾害较多。(4)、对汾河河漫滩不同站位沉积物中Hg、Cd、Pb和Zn元素进行了形态分析,形态分析中各元素的“非稳态”含量可以反映不同站位人为因素的影响。Hg、Cd、Pb和Zn四种重金属中,Hg的迁移环境风险最低,Cd的环境风险最高,Pb和Zn存在潜在危害。当环境条件改变,沉积物中Cd最易活化释放到水体中,形成新的污染源,应引起足够重视。(5)、重金属来源研究采用与流域岩石重金属含量对比,结合相关分析和因子分析法,并与汾河流域工业发展状况进行对照。自然的汞主要来自P1x、C2、C3、O2f等沉积岩地层,岩浆岩和变质岩对汞污染的贡献很少。含镉偏高的地层主要是T1和C3。人为的汞镉污染主要与山西工业燃煤及采煤业有关。其他轻微或中等污染的重金属在沉积物中都显示不同程度的富集,除来自于流域岩石的自然风化和侵蚀外,也与流域内的人口激增和工商业蓬勃发展有关。此外,推测重金属富集的原因可能与汾河地堑的独特的地质构造有关,该结论有待进一步研究探讨。更多还原

【Abstract】 The Fenhe River watershed is a region where the industry and agriculture are developed. The Fenhe River watersheds plays a key role in economic development in Shanxi Province. In recent years, the annual precipitation decreased and varied seasonally, the ecological functions of Fenhe River have degraded greatly.As more and more direct and indirect pollutants from commercial, industrial, and recreational uses of the watershed discharge into Fenhe river, Environmental pollution and damage accidents which brought about has gradually become a prominent problem, and are danger to human health. Heavy metals pollution is increasingly concerned because of their no-degradation and characteristics that they can be rich and the concentrations may be increased as toxins are passed up the food chain.This paper studies the following aspects:The water geochemical survey including water, suspended matter and bottom mud and the geochemical fluvial sediments survey are carried out. The eco-geochemical evaluation about heavy metals Hg, Cd, Pb, As, Cr, Cu, Ni and Zn are executed. The abundance of isotopes 210Pb of floodplain sediments was tentatively measured. The deposition rate of sediments and sediment flux of heavy metals in Fenhe River are estimated. The main period of pollution are deduced. The chemical speciation of high-heavy metals samples is analyzed, and the ecological danger, the sources and migration of heavy metals are discussed.The following results and knowledge were obtained:(1) Heavy metal content is the lowest in suspended matter, the second high in water and the highest in bottom mud in Fenhe River. As a whole, heavy metal content tends to increase from Taiyuan to Hejing.The content of heavy metals Hg, Cd, Pb, As, Cr, Cu, Ni and Zn in filtered water is lower in Huanghe River than in Fenhe. And higher in Linyi than in Yumenkou. Heavy metal concentrations of the suspended matter in Fenhe River during flood periods are higher than during drought periods. It shows that in monsoon surface running water washed pollution source clearly. Compared with Huanghe, the heavy metals pollution in botton mud is more serious in Fenhe river. All in all, the water of Fenhe river give obvious pollution to Huanghe River.(2)The pollutants in Fenhe River stay mainly in the sediments of Taiyuan basin and Linfen basin. The maximum concentrations of heavy metals in sediments focus approximately on the depth of 12～66 centimeters in Taiyuan basin, and on the depth of 88～100 centimeters in Linfen basin. The maximum concentrations of sediment flux of heavy metals occur after 1980 which is the peak-period of anthropogenic input of heavy metals. Concentrations of heavy metals have a positive correlation with sediment flux, which is different from the rivers in the south. Taiyuan basin and Linfen basin are the reservoirs where the pollutants are assembled and also new pollution source of Huanghe River.(3) The pollution degree of heavy metals in water and sediments was appraised fully and impersonality. According to comprehensive evaluation, the water in Fenhe river has been poluted. Hg, Cr and Cd pollution in Hejin section belong to V category according to GB3838-2002. The content of metal Hg in six sections belong to V category. The main pollutants in the river are Hg and Cd. Concentrations of Pb, As, Zn, Cu and Ni in water are lower, and the pollutions are slighter. The main pollutants in the fluvial sediments are also Hg and Cd. The pollutions of other heavy metals in the fluvial sediments are also slighter. The pollution levels of heavy metals in the sediments of six sedimentary columns were in the following orders:MHH1420FU>MHH1419> MHH1418> MHH1421> MHH1414> MHH1417. All sedimentary columns were seriously polluted by heavy metals except MHH1418, that is to say, the service functions of ecological system were seriously degraded, the ecological environment was destroyed, and more ecological problem and disaster appeared.(4)The speciation analysis of the elements Hg, Cd, Pb and Zn was carried out among the sediment in different stations. The content of heavy metals unsteady states reflected different influence of anthropogenic factors among different stations. Among Hg, Cd, Pb and Zn, the environment risk of mercury is the lowest, while the environment risk of Cd is the highest. Pb and Zn are potentially hazardous. When the conditions and environment are changed, Cd in the sediments easily become active and is released into water, which will become a new pollution source. Therefore more attentions should be paid.(5)The sources of heavy metals are identified by being compared with concentrations of heavy metals in the rocks of the Fenhe River watersheds, by carrying out correlation analysis and factor analysis, and by being compared with the development status of industry in the Fenhe River watershed. The natural origin of mercury is from sedimentary rocks such as stratum P1x, C2, C3 and O2f. Concentrations of mercury are very low in metamorphic rocks and magmatic rocks. Concentrations of cadmium are high mainly in stratum T1 and C3. The anthropogenic pollutions of mercury and cadmium are chiefly affected by industrial coal combustion and coal mining. The other heavy metals, having slighter or medium pollution and being rich in sediments in different degrees, come from the natural weathering of the rocks of the Fenhe River watersheds, and are influenced by the rapid growth of its population, industry and commerce. In addition, we presume that the accumulation of these heavy metals is perhaps related with geological structure of Fenhe Graben, and the conclusion needs further research.更多还原