【作者】 徐争启；

【导师】 倪师军； 张成江；

【作者基本信息】 成都理工大学 ， 地球化学， 2009， 博士

【摘要】 由于矿山环境问题及表现形式不同,硫化物型矿山一直是人们关注的重点,而氧化物型矿山由于不产生酸性矿业排水(AMD)等明显的环境问题,人们对氧化物型矿山环境问题重视程度不够,研究程度较浅,但氧化物型矿山产生的环境问题和潜在的环境问题不容小视。本论文在国家科技攻关项目(2005BA901A03)和国际合作项目(2005DFA20900)支持下,选择我国著名的氧化物型矿山——攀枝花钒钛磁铁矿作为研究对象,以矿区不同环境介质作为研究载体,采用ICP-MS、ICP-OES等分析方法,系统研究了矿业活动过程中水环境、土壤环境、大气环境、植物等矿山环境介质中重金属的地球化学特征。取得了以下成果:(1)对重金属在矿区水—悬浮物—水系沉积物系统中的地球化学特征进行了研究,发现水体重金属含量很低,悬浮物及沉积物中的重金属含量较高;Cu、Zn、Co、Ni、Fe、As在悬浮物中的含量高于沉积物,Pb、V、Ti、Cr在沉积物中的含量高于悬浮物;分配系数反映活动性最强的是Hg,其次为As和Ni,Ti最不活泼;从沉积物形态分析结果来看,攀枝花矿山水系沉积物中Ti最稳定,V、Cu、Cr较稳定,Zn、Mn、Co、Ni较活泼;潜在生态危害指数法评价发现水系沉积物中大多数重金属元素都发生了中度和重度污染,其中Cu、Co、V和Ti受到重度污染以上,从潜在生态指数来看,所有点均为轻微生态危险,总体上矿区水系沉积物中重金属的潜在生态危害程度不高,对环境的影响有限。(2)通过土壤与水之间钒的分配系数实验、渗透实验、土壤中钒的迁移实验以及土壤中钒的化学形态分析,研究了土壤中钒的地球化学活动性、迁移特征。通过实验分析了钒在土壤中的各种参数及特征。等温吸附曲线表明,壤土对钒的吸附能力最强,砂土对钒的吸附能力较差,特定的温度区间和K_d值呈正相关关系。pH值对分配系数在壤土和砂土两种类型土壤的变化趋势一致。不同类型土壤中渗透系数不同,砂土的吸附系数明显高于壤土。土壤中残渣态钒占总钒的绝大多数,表明钒在土壤中是不活泼的。(3)研究了矿区土壤中重金属的地球化学特征,评价了土壤中重金属的潜在生态风险。土壤中各重金属以采矿场和排土场为中心分布;元素在剖面上的变化总体上仍是表层高于下层;通过相关分析及聚类分析,土壤中重金属元素则被分为两类:Zn、Cd、Pb、Hg、As和V、Co、Ti、Cu、Ni、Cr、Mn,不同区域采集样品,重金属相互关系及聚类结果不同,其原因可能与采样点土壤类型及性质有关,也可能由不同区域人为污染程度不同引起;通过对土壤中重金属进行潜在生态危害评价,表明所测定的攀枝花矿区表层土壤中重金属元素大多数都发生了中度和重度污染,从潜在生态危害指数来看,仅有一个点为很强生态危害,总体上矿区土壤重金属生态危害程度不高。(4)研究了攀枝花矿区及矿业活动区两类大气尘重金属地球化学特征。研究结果表明,攀枝花矿业活动区大气降尘和近地表大气尘中重金属的含量很高,特别是V、Ti、Fe等与攀枝花矿业活动有关的重金属元素的含量特别高,是成都经济区其他城市的数倍到十余倍。近地表大气尘中重金属的形态分析研究表明,Cu、Pb、Zn、Co、Ni、Mn等6种元素的交换态和碳酸盐结合态的含量较高,对环境有重要影响;V、Cr对环境影响较小;Ti元素残渣态占了99%以上,对环境影响很小。近地表大气尘的粒度和矿物学研究表明,近地表大气尘的粒度很细,大都在80um以下,主要集中在20-50um,个别点在20um以下;矿物成分总体上以石英为主,其次为长石和石膏,再其次为碳酸盐矿物。(5)研究了不同区域树芯年轮样品中的重金属特征。结果发现树芯年轮在一定程度上可以反应矿区重金属的污染变化,不同区域树芯年轮重金属与该区域的矿业活动有一定的关系;通过对比,发现树芯年轮中重金属与根系土呈显著正相关。发现树芯中的元素不仅仅来自土壤,还有可能来自于大气沉降等途径。(6)分析了不同介质中重金属的相互关系及重金属的来源、存在形式和转化关系。矿区不同介质中的重金属有两方面的来源:一是来源于含重金属的基性超基性岩石的自然风化,二是由于人为对钒钛磁铁矿的开采、选矿和冶炼等矿业活动,其中矿业活动是重金属的最主要来源。矿区不同介质中重金属的存在形式不同,大部分重金属元素主要存在于矿物晶格中,以残渣态的形式存在,部分元素有机结合态和碳酸盐结合态所占比例也较高。矿区不同介质中重金属的活化及迁移过程以物理活化和物理迁移为主。在自然因素下重金属与其他所有元素一样有相同的转化关系,即通过风化作用与沉积作用在岩石—土壤—水体及植物之间转化与循环。在人为因素下,在矿业活动的不同阶段重金属通过废气(扬尘与废气)、废液(废水)、固体废弃物(废渣、废石、尾矿)在土壤、大气、水体、植物之间进行转化与循环。(7)对比了硫化物型矿山和氧化物型矿山重金属的地球化学特征,总结了氧化物型金属矿山的地球化学特征。发现氧化物型矿山与硫化物型矿山重金属环境地球化学特征有不同之处,也有相同之处。最大的不同是硫化物型矿山环境介质中亲铜元素含量远高于氧化物型矿山,氧化物型矿山最大的污染是大气尘重金属污染,硫化物型矿床最大的污染是酸性矿业废水污染。相同点是,无论氧化物型矿山还是硫化物型矿山,重金属的形态特征相似。更多还原

【Abstract】 Sulphide mines have always been the concerns of people because of their various forms and the resultant environmental problems,whereas oxide mines are paid less attention and not studied much because they do not cause obvious environmental problems such as acid mining drainage (AMD).However,the potential environmental problems caused by oxide mines can not be ignored.Under the support of the two projects,The National Scientific and Technologic Project (2005BA901A03) and The International Cooperation Project(2005DFA20900),the author chooses Panzhihua V-Ti-Magnetite,a famous oxide mine in China,as the subject of research.In this thesis, the geochemical characteristics of heavy metals in various environmental media in the zone(such as water,soil,atmosphere and plants) during the process of mining are systematically studied by using those media as research carriers and employing the analyzing methods of ICP-MS and ICP-OES.The research results are shown below:(1)The research on the geochemical characteristics of heavy metals in the system of water-suspended solid-sediment in the mining zone show that:the contents of heavy metals in water are very low,while those in suspended solids and sediments are relatively higher;the contents of Cu,Zn,Co,Ni,Fe and As in suspended solids are higher than those in sediments;the contents of Pb,V,Ti and Cr in sediments are higher than those in suspended solids.The partition coefficients show that:Hg is most active,As and Ni are less active,and Ti is least active.The morphological analyzing results of sediments show that in the sediments in Panzhihua Mining Zone, Ti is most stable,V,Cu and Cr are relatively stable,and Zn,Mn,Co and Ni are more active.The index evaluation on potential ecological risk shows that most heavy metal elements in the sediments are contaminated,whether heavily or in a medium degree,in which Cu,Co,V and Ti are contaminated heavily or even more severely.The potential ecological risk index shows that all places are in light ecological risk and generally the potential ecological risk of heavy metals in the sediments are not high and they have limited influence on environment.(2)The geochemical activity and transferring features of Vanadium in soil are studied by doing the partition coefficient and penetrating tests of Vanadium between soil and water and the transferring test of vanadium in soil as well as analyzing the chemical forms of Vanadium in soil.In the tests,various parameters and features of vanadium are analyzed.The adsorption isothermal curves show that loam soil is most absorptive to V,sandy soil is less absorptive,and V is positively correlative to K_d in certain temperature ranges.The changes of pH to the partition coefficient in both loam soil and sandy soil are identical.The penetrating coefficients in different soils are different and the absorbing coefficient of sandy soil is obviously higher than that in loam soil.In soil,most vanadium takes the form of residua,which shows that vanadium is not active in soil.(3)The geochemical characteristics of heavy metals in the soils in the mining zone is studied and the potential ecological risks of those heavy metals are evaluated.The heavy metals are distributed around the stope and dump and the change of the elements on the surface of the profile is generally greater than that on the underlayer.Through the correlation analysis and the clustering analysis,the heavy metals in the soil are classified into two classes:Zn,Cd,Pb,Hg and As belong to one class while V,Co,Ti,Cu,Ni,Cr and Mn belong to the other.For samples from different areas,the correlations and clustering results of those heavy metals are different.That may be caused by the type and feature of soil in the sampling places or the degree of man-made pollution in the area.The evaluation on the potential ecological risk of heavy metals shows that the contamination of most heavy metal elements in the surface soils in Panzhihua mining zone are medium or heavy.Judged by the potential ecological risk index,only one place are in strongly high ecological risk.Generally,the ecological risk of heavy metals in the zone is not high.(4)The geochemical characteristics of two kinds of atmospheric particle in Panzhihua mining zone and mining activity area.The results show that contents of heavy metals in atmospheric dust and near-earth-surface atmospheric particle in Panzhihua mining activity area are very high and the contents of the elements,such as V,Ti and Fe,related with mining activity are especially high and can be up to several or even more than ten times of those in other cities in Chengdu Economic Zone. The morphological analysis of heavy metals in near-earth-surface atmospheric particle shows that the contents of ion-exchange and carbonate-bound of Cu,Pb,Zn,Co,Ni and Mn are higher and have significant effect on environment,V and Cr have less effect on environment,Ti residua accounts for more than 99%and has very little effect on environment.The study on the granularity of near-earth-surface atmospheric particle and the mineralogical research show that the granularity of the near-earth-surface atmospheric particle is very thin,most are thinner than 80um and mainly fall in the range of 20-50um,and only some are thinner than 20um;the mineral are mainly composed by quartz,then by feldspar and gesso,and then by carbonate minerals.(5)The characteristics of heavy metals in the tree ring samples in different areas are studied. The results show that,in a certain extent,the tree ring can reflect the contamination degree of heavy metals in the mining zone and the heavy metals in the tree ring in different areas are related with the mining activity in the area.Through contrast,it is found that the heavy metals in the tree ring are obviously positively correlated with the root soil and the elements in the tree ring are not only from soil but probably from atmospheric deposition.(6)The correlation heavy metals in different media as well as the source,the existing form and the transform of heavy metals are studied.There are two sources for the heavy metals in different media in the mining zone:one is the natural weathering of basic and ultra-basic rocks that contain heavy metals and the other is the mining activity,and the latter is the main reason.Most heavy metal elements exist in mineral crystal lattice in the form of residua.For some elements,the proportion of their organic bound and carbonate-bound is also higher.The heavy metals in different media in the mining zone mainly activated and transferred physically.Under natural conditions,the heavy metals have the same transforming relation with all other elements,that is,transform and cycle between rock,soil and water under the action of weathering and sedimentation.Whereas, under the human conditions,heavy metals in different stages of mining activity transform and cycle between soil,atmosphere,water and plant by exhaust gas(raised dust and exhaust gas),liquid waste(waste water),solid waste(waste residue,mullock,gangue). (7)The geochemical characteristics of heavy metals in sulphide mines and oxide mines are contrasted and the geochemical characteristics of heavy metals are summarized.It is found that the geochemical characteristics of heavy metals in the two mines have not only similarity but also difference.And the biggest difference is that the content of chalcophile elements in environmental media of sulphide mines is far higher that in oxide mines and the biggest pollution for oxide mines is that caused by atmosphere dust and heavy metals,while the biggest pollution of sulphide mines is that caused by acid mining waste water.The similarity between the two mines is that their morphological features are same.更多还原