【作者】 廖香俊；

【导师】 张本仁；

【作者基本信息】 中国地质大学 ， 地球化学， 2008， 博士

【摘要】 矿产开发活动及其废弃物的排放带来了一系列影响深远的环境问题,矿业开发对环境污染的预防和治理、废弃地的生态恢复已成为全世界面临的紧迫任务之一,也是当今世界重要的科学研究课题之一。石碌铁矿是亚洲最大的富铁矿,已有70多年的开采历史,产生了大量的废弃物,2007年开始正式规模开采铜钴矿,并开展铜钴矿的加工和冶炼,矿区的环境压力越来越大,而矿区所在地就是昌江县县城,因此,矿区环境污染的防治和生态保护十分紧迫。本文以地球化学理论为指导,以岩(矿)石—尾矿—土壤—水—水系沉积物—植物—人为系统,采用地球化学、生态学等多学科协同及野外调查—实验测试—栽培试验—模拟试验—综合研究等方法,研究了矿区环境污染的历史、现状、发展趋势及其主要影响因素,研究了矿区环境污染的植物治理与化学治理方案。研究取得以下主要成果:1、从岩石地球化学特征着手研究了矿区环境的地球化学背景。研究表明,研究区As、Cd、Cu、Hg、Cr、Pb、Zn等有害元素在侵入岩中含量一般都高于全海南岛侵入岩的背景水平,其中,中元古代花岗片麻岩中除Pb外的其他元素含量是最高的;沉积—变质岩中各元素也具有同样的分布特点,且铁矿体、铜钴矿体围岩石碌群中As、Co、Cr、Cu、Mn、Ni、Fe的含量最高。对于矿山开采活动的主体——铁矿石和铜钴矿石而言,铁矿石中除Fe外其他元素含量一般较低,但其围岩中Hg、Ni等元素的含量高;铜钴矿石中除Cu、Co元素外,As、Cd、Hg、Ni、Pb、Zn的含量也很高。因此,铁矿和铜钴矿的开采,都可能带来As、Cd、Hg、Ni、Pb、Zn、Mn等伴生元素以及成矿元素Cu、Co、Fe对环境的影响。2、对矿区土壤、尾矿、水系沉积物、水、植物等各环境介质的环境地球化学进行了研究。(1)从海南岛全区土壤到研究区内区域性土壤、与矿山开采影响密切关联的局部土壤、尾矿库区上游土壤、尾矿库区下游土壤,有害元素含量逐步升高,特别是尾矿库区下、上游土壤中元素含量比值明显大于1,说明尾矿是影响其下游土壤有害元素含量的源头。结合表层土壤的富集因子进行的研究区内区域土壤有害元素地球化学异常的解释,表明其成因大多为人为作用即矿山开采所致。(2)研究区内的各期尾矿库的尾矿和排土场废石中有害元素含量较高,铜钻尾矿中有害元素的含量高于铁矿尾矿。尾矿中最稳定的元素是Cr,有机结合态是尾矿中较常见的有害元素的赋存形式;各期尾矿库表层的有害元素有效态一般高于深层;铜钴尾矿中大部分有害元素的有效态含量及潜在活动性比铁矿尾矿更高。(3)矿区内上世纪八十年代和当今水系沉积物有害元素特征研究表明,近20年来水系沉积物中有害元素均呈增加态势。对比八十年代与当今两个时间点的有害元素含量,可知尾矿库和铁矿排土场等对水系沉积物中有害元素的改变存在一定时间的延迟,这种延迟也正是尾矿库地球化学演化过程的真实写照。(4)研究区内地表水在迳流过程中与河床的岩石、土壤、水系沉积物等发生物理、化学、生物及吸附等作用,岩石、水系沉积物、土壤中某些元素如铁、锰及重金属等被水溶解进入水中,使水中元素含量增加,石碌河矿区段河水的铁、锰元素普遍偏高,尤其是与Fe1铁矿尾矿库及铜钴矿尾矿库(Cu-Co2)相连的支流更高,这与尾矿库淋滤水、复杂的区域水岩交换有关。研究区地下水中铁、锰元素含量总体偏高,在矿区尾矿库地段,由于受尾矿渗透的影响,尾矿中铁、锰金属元素和硫化物等组分经溶解进入地下水,使地下水中重金属元素含量剧增。(5)不同生长背景区小油菜对土壤中有害元素的吸收特性均表现为根大于叶,叶大于茎,而且各部位对土壤的地球化学性质反应灵敏,小油菜和土壤有害元素含量具有正相关特征;土壤中某些元素如Cd、Pb、Zn、Hg等更易于被小油菜吸收。3、矿山开采、尾矿和矿山废石等改变了矿区土壤、地表水和地下水中的有害元素组成,降低了土壤和水的环境质量,并与区外土壤和水形成了鲜明的对比,最终影响到农作物的安全性。矿区土壤As、Cd、Cu、Hg、Zn等元素大多超过国家土壤环境质量1级标准,尾矿库、排土场下游土壤环境质量更差,有的元素超过3级标准。根据内梅罗指数,矿区石碌河尾矿库河段地表水属严重污染,排土场下游地表水属中度污染,明显不同于矿区外围地表水;尾矿库周围地下水属于严重污染。矿区尾矿库下游土壤中种植的小白菜受到污染,As、Cd、Hg、Pb含量超标。矿区环境质量总体较差。矿区尾矿库尾矿、排土场废石是影响矿区环境质量的主要因素。4、对土壤的环境质量演化预测表明,研究区内因矿山开采和尾矿库等影响,矿区土壤环境质量呈总体下降趋势;石碌河整个河段河水,在今后30～35年内,其中锰、铁等元素和硫酸盐、硝酸盐等组分含量将超过生活饮用水卫生标准;矿区水系沉积物中有害元素含量也会持续增长。总之,矿区不同环境介质的环境质量将会向下降的趋势进一步演化,随着铜钴矿的规模开采和冶炼的进行,矿区面临的环境压力将越来越大。5、为寻找尾矿治理的有效植物,开展了尾矿库区的自然植被调查。调查表明,尾矿库中自然生长的植物有40多种,其中狭叶香蒲在海南是首次发现;狭叶香蒲、水蓼、水竹、白茅、斑茅等是尾矿库中的优势植物,其中水蓼、水竹、狭叶香蒲对Fe、Mn、Cu、Pb、Zn、As、Hg等有害元素有较强的吸收能力和耐性;尾矿库区植物的种类、盖度、多样性与尾矿存放的时间及其N、P、K等养分含量关系密切,尾矿存放时间越长,N、P、K等养分含量越高,植物种类越多、盖度和多样性指数越高。6、开展了尾矿库区自然生长的优势植物水蓼、狭叶香蒲、水竹和海南优势热带作物对有害元素的吸收性和耐性栽培试验研究,取得了重要成果。(1)水蓼具有较好的治理尾矿中Cu、Pb、Zn、Mn的能力:水蓼对Mn具有很高的吸收能力、富集能力和耐性,对Mn的转移系数、累积系数均大于1,地上部分Mn的含量可高达13681.5mg/kg,具备了对Mn作为超积累植物的特征;水蓼吸收Mn时,对Fe、Cu、Zn等有害金属很少会发生拮抗作用。(2)狭叶香蒲对Cu、Pb、Zn等有害金属具有较强的吸收能力和耐性,其对环境中Cu、Pb、Zn的最大耐性浓度分别为2000mg/kg、350 mg/kg、10000mg/kg,远远高于这些元素在尾矿中的含量。(3)剑麻对Pb、Cd等有害金属具有较强的耐性和富集能力,环境中Pb、Cd分别达到15900mg/kg、1000mg/kg时,仍有较强的耐性;Pb、Cd的最高含量,剑麻地上部分别为2220.26mg/kg、2348.08mg/kg,地下部分分别为2544.78mg/kg、16620.52mg/kg,地上部分和地下部分Pb、Cd的含量都很高;尽管Pb、Cd等有害元素在剑麻中转移系数小于1,但剑麻的生物量大,对尾矿中Cu、Cd有较好的治理效果。剑麻的尾矿栽培模拟试验表明,H.11648品种吸收有害元素能力强,并能使尾矿中有害元素有效态减少,是尾矿治理的较好的剑麻品种。7、为探讨尾矿化学方法治理的可能性,开展了模拟试验。尾矿的EDTA及盐酸淋洗模拟试验表明,在酸性或在有络合物环境中,尾矿中尤其是新尾矿中有害金属不稳定,易于从尾矿中迁出。尾矿化学治理模拟试验表明,石灰、有机肥和生物肥对老尾矿改良效果不明显,而对新尾矿具有一定的改良作用,0.1%石灰和1%的有机肥对新尾矿的改良效果最好。8、研究区主要的污染源是尾矿库尾矿和排土场废石,其治理以植物方法为主,化学方法相配合;尾矿治理植物的选择遵循“适者生存”自然法则,以尾矿库区自然生长的优势植物为主;污染源的治理要分区域采取不同的方案。创造性提出了热带地区铁铜钴矿山环境治理的新方法。尾矿库干燥区的治理,采用以种植剑麻为主,以适量石灰和有机肥化学治理为辅的联合协同方案,新尾矿库治理区石灰的使用量为0.1%,剑麻种植坑内有机肥的使用量为1%,剑麻的种植网度为3.6×1.2m就可达到较好的治理效果:按国家二级土壤环境质量标准,旧尾矿库Cd的修复年限为2年,铜钴尾矿库Cd的修复年限为2年,新铁矿尾矿库Cd的修复年限为4年。尾矿库种植剑麻并进行加工,每公顷尾矿库可创年产值7.29万元,经济效益明显。尾矿库废水沼泽区的治理,主要采用植物治理方案,废水区种植狭叶香蒲,废水区与干燥区过度带种植水蓼和水竹,并让其它生物自然生长,形成人工与自然生长的植物群落。狭叶香蒲和水竹吸收有害元素后不会通过食物链传递给人或其它生物,它们还有较高的经济价值,可用于编制器具和工艺品。排土场的治理,一是要采取工程措施,防止发生滑坡和泥石流,二是要在植树复垦的基础上,适当套种剑麻进行治理。更多还原

【Abstract】 Deposit exploitation and mining waste discharge have been bringing a series of far-reaching environmental problems to human living.All over the world,people are facing to an urgent task, that is,how to prevent and restore the environmental pollution and ecology recondition in the discarded area for the deposit exploitation.It is now becoming one of the important subjects of scientific research.Shilu mine is the biggest iron-enrich ore deposit in Asia.It has been mined for more than seventy years,and inevitably discharged a large of waste around this region.In 2007, the Copper-Cobalt ore deposit in this mine was begun to exploit formally in industrial scale,and subsequent processing and smelting for the Cu-Co ore were also carried out.Environmental pressure on this mining area is getting more and more serious.Moreover,Changjiang County just lies in this mining area,so it is very urgent to do the environmental prevention and ecology protection there.Based on the geochemical theory,and set the rocks（ores）,tailings,soils,waters,stream sediments,plants and human activities as an associated system,the pollution history,actuality and evolution tendency and the primary influential factors of the environment in this mining area were studied in this paper.An integrated study method was accepted in this study,it includes geochemical,ecological,and field surveys,and also includes the experimental analysis,planting test,simulating test and comprehensive methods.Consequently,a planting and chemical recondition scheme on the environmental pollution in this mining area was studied and developed. This study includes the following eight correlative parts,and summarizes the following results and conclusions.1.Geochemical background of this mining area was surveyed and studied based on the rock geochemical characteristic.The results show that the contents of toxic elements,such as As,Cd, Cu,Hg,Cr,Pb and Zn,in the intrusive rocks of this mining area are generally higher than their whole background level in Hainan intrusive rocks.These toxic elements,except for Pb,of the mesoproterozoic granite gneiss were highest in this mining area.The abundance of these toxic elements of the sedimental- metamorphite rocks in this area has similar parting properties. Moreover,Shilu Group,the host rocks of the iron-ore and Copper-Cobalt ore bodies contains the highest contents of As,Co,Cr,Cu,Mn,Ni,and Fe in this mining area.For the main bodies,the iron-ore and Copper-Cobalt ore,exploited in this mine,many elements except for iron are generally low in the iron-ore,and however,the contents of Hg,Ni and so on are very high in its host rocks.Contrarily,the contents of toxic elements,such as As,Cd,Hg,Ni,Pb and Zn in the Copper-Cobalt ore,are high with ore-forming elements Cu and Co.Therefore,the exploitations of both iron and Copper-Cobalt ores are quite possibly to bring the environment pollution with ore-forming elements,such as Fe,Cu,Co and the accompanying elements,such as As,Cd,Hg, Ni,Pb,Zn and Mn,etc.2.Environment geochemistry study were also carried on several environmental media,such as soils,and tailings,waters,stream sediments and plants,etc.and summarized the following results.（1）From the whole soils in Hainan,to the regional soils in Shilu region,to the local soils closely affected by the exploitation in the mining area,and to the upriver and the downriver soils of the tailing dam,the contents of the forementioned toxic elements are getting higher and higher. Especially,the abundances ratios（enrichment）of these toxic elements in the two latter are far higher than one.It indicates that the tailings are the possible source of these toxic elements polluted the downriver soils.According to the explains for the geochemical abnormality of the toxic element enrichment factors in the regional surface soils,the cause of the pollution was possibly farther deduced to the human action,i.e.the mine exploitation.（2）The contents of these toxic elements are quite high in the tailings and waste rocks for every period of tailing dam and dumping sites.The toxic element contents in the Cu-Co tailings are higher than that in the Fe tailings.Chromium is the most stable element in the tailings,and the organic combination is a quite usual occurrence form for these toxic elements in the tailings. The organic combinations of these toxic elements are higher in the surface layers than that in the down layers.The contents of the organic combinations and the potential activities of these toxic elements in the Cu-Co tailings are much higher than that in the Fe tailings.（3）From a comparison study on the toxic elemental characteristic of the present and the last century’s stream sediments in this mining area,it was found that the contents of the toxic elements in these stream sediments have an increasing tendency.Comparing the toxic elements contents of these two stages in this mining area,we found that for the stream sediments,there was a time delay on the alteration of the toxic elements by the tailing dam and the iron dumping sites.This delay is factually the geochemical evolution of the tailing dam.（4）During the surface water flowing along the river,it happen a series of physical,chemical and biological interactions and absorption with the rocks,soils and stream waters in the riverbed. By this way some toxic elements such as Fe,Mn and heavy metals were dissolved into the water, and their contents in river water increase.So the contents of Fe,Mn and other elements of the river water are general enriched in Shilu mining region,especially much higher in the distributaries of iron（Fe1）tailings dam and Copper-Cobalt（Cu-Co2）tailings dam.It is also related to the interchange process between the leach water from the iron tailing dam,sewage from the ironworks and the complex tectonic rocks.Affected by the infiltration of the tailings dam,the metal elements such as Fe,Mn and sulfides,etc.of the tailings were dissolved into the groundwater on the sections of the tailings dam in this mining area,therefore,the contents of heavy metal elements of the groundwater are rapidly increase as a whole in this mining area.（5）The absorption of the toxic elements in soils by Brassica Chinensis in different growing backgrounds shows that the adsorb ability decreases from roots to leaves and to stems.However, every part of the Brassica Chinensis is sensitive to the geochemical property of the soils.So the toxic elements have positive relations between their contents in Brassica Chinensis and in the soils.Some metal elements in soil such as Cd,Pb,Zn,and Hg,etc.are liable to be absorbed by Brassica Chinensis.3.The toxic elemental compositions of the soils,surface water,and groundwater were changed by the exploitation,tailings and waste rocks in the mining area.Consequently,the environmental quality of the soils and waters was also deteriorated in the mining area,and was quite distinctive from the soils outside this mine.Finally this environment deterioration is getting a dangerous effect to the crops planting.Most of contents of As,Cd,Cu,Hg and Zn,etc.from the soils in this mining area are beyond the 1^stlevel of the national soil standard.The environment quality was much worse for the downriver soils of the tailings dam and the refuse dumps,and some elements were especially beyond the 3^rdlevel of the national soil standard.According to NMR’s index,in Shilu mining area,the surface water in the tailing dam reach of Shilu river is badly polluted;surface water of the downriver is secondarily polluted;and they are evidently different from the outside surface water;the groundwater around the tailing dams is also badly polluted.Brassica Chinensis planted in the downriver soils of the tailing dams were polluted,the contents of As,Cd,Hg and Pb in these Brassica Chinensis were beyond the national standard. Totally,the environment quality in this mining area is bad.The primary influential factors are the pollutions from the tailings in the tailing dams and waste rocks in the refuse dumps.4.The environmental quality evolution of the soil in the mining area was surveyed and evaluated.The result shows that the exploitation and tailing dams and so on have bad affected the environment in this mine,and the environmental quality has a worsen tendency in general.In the coming period of 30 to 35 years,the contents of Fe,Mn and other toxic elements and sulphate and nitrate compositions contained in the whole Shilu river will exceed the drinking water standard.The toxic element contents of stream water in this area will be continuously increasing. Anyway,the environmental qualities of different environmental media in this mining area will go along with a worsen evolution tendency.The environmental pressure is increasing with the industrial scale exploitation and smelting of cupper-Cobalt in Shilu mining area.5.In order to find out some effective plants to treat the pollutions in the tailings,a survey on the natural vegetation was done in the area of tailing dams.We found that there were more than forty of natural plants growing about this tailing dams;and fortunately that,one of Typhaceae angutifolia was first found in Hainan province;the dominant plants are Typhaceae angutifolia, Polygonum hydropiper,Phragrnites.Karka,Imperata cylindrica,Saccharum arundinaceum, etc.in this area of tailing dams.Polygonum hydropiper,Phragrnites.Karka and Typhaceae angutifolia have strong absorbing capacity and tolerance to the toxic elements,such as Fe,Mn, Cu,Pb,Zn,As and Hg,etc.The plant species,plant coverage,and variety are closely correlated with the storage time of tailings,and the nutrient contents of Nitrogen,Phosphorus,and Potassium,etc.The longer the storage time of railings,the higher the contents of these nutrients, and the more the plant species,coverage,and variety.6.A pilot study was gone on the planting of the natural dominant plants,such as Polygonum hydropiper,Typhaceae angutifolia,Phragmites.Karka are the tropic plants in Hainan.The planting study was focused on the absorption and tolerance of the toxic elements into these plants in the area of tailing dams.We have got the following important conclusions.（1）Polygonum hydropiper and Typha Orientalis have strong ability to decontaminate the toxic elements such as Cu,Pb,Zn,Mn,etc.from the tailings.Polygonum hydropiper has a very high capacity of absorption,enrichment,and tolerance to Manganese.Both transfer and cumulation coefficients of Mn in Polygonum hydropiper are higher than one.The contents of Mn in it’s over ground parts can accumulate to 13681.5 mg/kg,moreover,during the absorption of Mn,it has no antagonistic action;so it is totally the strongest super-accumulating plant for Mn absorption.（2）Typhaceae angutifolia has strong absorption and tolerance capacities to the toxic elements,such as Cu,Pb,Zn,etc.The max tolerant capacity to these toxic elements is 2000 mg/kg,350 mg/kg and 10000 mg/kg,respectively,which is far higher than that in the soil.（3）Agave Sisalana has strong tolerance and accumulation ability to the toxic elements such as Pb and Cd.It can stand up and tolerate high levels of these toxic elements,although the contents of Pb and Cd are as high as 15900 mg/kg,400 mg/kg,4000 mg/kg,and 1000 mg/kg, respectively.The contents of these toxic elements in its over ground parts are respectively 2220.26 mg/kg,321.87 mg/kg,2702.6 mg/kg,and 2348.08 mg/kg,while the contents in its underground parts are respectively 2544.78 mg/kg,4324.75 mg/kg,19399.08 mg/kg,and 16620.52 mg/kg.Both parts contain high contents of Pb and Cd.Although the transfer coefficients of these toxic elements in Agave Sisalana are less than one,its biomass is much large in this area,so it has an effective function to decontaminate the toxic elements of Pb and Cd. During the planting test of Agave Sisalana in the tailing dams,we found that one variety of Agave Sisalana,H.11648,has a stronger absorptive ability to these toxic elements,and can decrease their organic combinations,so it is a better variety to treat the tailings.7.To search out a possible chemical method for treating the railings,simulating test was carried.The eluting of the tailings using EDTA,and hydrochloric acid shows that,in acid or complex condition,the toxic metal elements are unstable in the tailings,especially,in the fresh railings.These toxic metal elements were easily to leach out from the tailings.The simulating results indicate that usage of lime,organic manure,and biological fertilizer is ineffective to improve the stale tailings,although it has effect to the fresh tailings to some extent.A mixture of lime of 0.1%and organic manure of 1%is possible the most effective to improve the fresh tailings.8.Main pollution sources in this mining area are from tailings filled in the tailing dams and from waste rocks in the refuse dumps.The important effective measure for the recondition of this mine is planting plants,and associated with chemical disposal method.The selection principle of plants for environmental recondition should follow the natural law,"the survival of the fittest". The dominant plants naturally growing in this area are the primary and effective selection.The treating project for different pollution sources should be different for different sections in the mining area.An innovative project was developed in this study;and it is effective to the tropic environmental recondition of Fe-Cu-Co mine.For the environmental recondition of dry sections in the tailing dams,a combined and synergistic project should be effectively taken.Planting of Agave Sisalana is the primary measure, and the chemical treat,with lime and organic manure,is an accessorial measure.The proportion of lime used to treat the new tailing dams is 0.1%,and organic manure used to plant Agave Sisalana is 1%.The planting distance of 3.6×1.2 m in girding is efficient enough to the environmental recondition.By the 2^ndlevel of the national soil standard,the rehabilitating terms of Cd in the old tailing dams are 2 years,respectively,and the terms of Cd in the Cu-Co2 tailing dams are respectively 2 years,while the terms of Cd in the new tailing dams is 4 years. The planting and processing of Agave Sisalana in the tailing dams has notable economical benefit,it can get an annual production value of 72.9 thousands Yuan per hectare of tailing dam.For the environmental recondition of the mars with wastewater in the tailing dams,a primary project is planting plants.In the wastewater sections,Orientalis Presl should be planted; Polygonum hydropiper and Phragmites Karka should be planted in the intermediate zones,while let the other plants grow naturally;and then the phytobiocoenose was forming by the planting and naturally growing plants.The toxic elements absorbed into Typhaceae angutifolia and Phragmites Karka can’t transfer to human and other bodies by food chain.These two of plants can be also used to make art ware and produce economic values.For the environmental recondition of the refuse dump,an engineering measure should be first taken to prevent the landslide and mud-rock flow;and secondly,basing on the tree planting and re-cultivating,the interplant of Agave Sisalana should be a helpful measure.更多还原