| 西藏多不杂铜矿区土壤与河床沉积物中重金属元素特征及其环境意义 |
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| 引用本文： | 陈振宇,王松,赵元艺.西藏多不杂铜矿区土壤与河床沉积物中重金属元素特征及其环境意义[J].地球科学与环境学报,2020(3):376-393. |
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| 作者姓名： | 陈振宇 王松 赵元艺 |
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| 作者单位： | 中国地质大学（北京）地球科学与资源学院;中国地质科学院矿产资源研究所自然资源部成矿作用与资源评价重点实验室 |
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| 基金项目： | 中国地质调查局地质调查项目(DD20160330);中国地质科学院基本科研业务费专项资金项目(YK1710-0)。 |
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| 摘 要： | 西藏多不杂铜矿是一大型斑岩型富金铜矿床,已探明铜资源量超过400×104 t,目前尚未开发且研究主要集中于找矿与地质成矿等方面,很少进行环境方面的研究。为了解西藏多不杂铜矿在未开采前矿区重金属元素的富集状况和迁移特性,对多不杂铜矿区地表土壤和萨玛隆河河床沉积物进行了样品采集,测试Cu、Pb、Zn、As、Cd、Cr、Hg等7种重金属元素含量和赋存形态;采用地累积指数法、内梅罗综合污染指数法、风险评估编码法对矿区重金属元素的富集程度和生物活性进行评价。结果表明:多不杂铜矿区地表土壤和萨玛隆河河床沉积物中的多数重金属元素含量分配受到多不杂铜矿的影响很大,且二者具有显著的相关性;多不杂铜矿区地表土壤中Cu尤为富集,含量最高达到21020.000×10-6,超过《土壤环境质量标准》(GB 15618-1995)中Ⅲ级标准的50倍,综合污染指数为39.43,达到重度污染级别,多数样品的地累积指数也达到极强污染级别,且其生物活性为中度风险,容易迁移转化,对环境的影响很大;萨玛隆河河床沉积物中Cu最高含量为2406.000×10-6,为Ⅲ级土壤环境质量标准的6倍,其综合污染指数为38.13,显示重度污染,污染率为91.6%,但其生物活性为低风险级别,迁移能力较弱,对环境的影响不是很大,但仍不可轻视;Cd虽然含量不高,低于Ⅲ级土壤环境质量标准,但是其在河床沉积物中主要以碳酸盐结合态存在(占比为48.01%),生物活性达到极高风险级别,对环境影响较大;Pb、Zn、As、Cr、Hg含量普遍较低,且生物活性较弱,能够稳定存在于土壤中,基本不会对环境造成影响。
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| 关 键 词： | 重金属元素 土壤 沉积物 形态分析 地累积指数 综合污染指数 生物有效性 西藏 |
Characteristics and Environmental Significance of Heavy Metal Elements from Soil and River Bed Sediments in Duobuza Copper Mining Area,Tibet, China |
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| CHEN Zhen-yu,WANG Song,ZHAO Yuan-yi.Characteristics and Environmental Significance of Heavy Metal Elements from Soil and River Bed Sediments in Duobuza Copper Mining Area,Tibet, China[J].Journal of Earth Sciences and Environment,2020(3):376-393. |
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| Authors: | CHEN Zhen-yu WANG Song ZHAO Yuan-yi |
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| Institution: | (School of Earth Sciences and Resources,China University of Geosciences,Beijing 100083,China;MNR Key Laboratory of Metallogeny and Mineral Assessment,Institute of Mineral Resources,Chinese Academy of Geological Sciences,Beijing 100037,China) |
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| Abstract: | Duobuza copper deposit in Tibet is a large porphyry type of gold-rich copper deposit, and the proven amount of copper resource is more than 400×104 t. At present, it has not been exploited, and the researches mainly focus on prospecting and geological mineralization, and little environmental research has been done. In order to understand the enrichment and migration characteristics of heavy metal elements in mining area before the development of Duobuza copper deposit, the surface soil and sediment of Samalong river bed in Duobuza copper mining area were collected, the contents and speciations of seven heavy metal elements, including Cu, Pb, Zn, As, Cd, Cr, Hg, were tested;meanwhile, geoaccmulation index method, comprehensive pollution index method and risk assessment code(RAC) method were used to evaluate the enrichment degree and biological activity of heavy metal elements in mining area. The results show that the distributions of most heavy metal elements in surface soil and sediment of Samalong river bed are greatly affected by Duobuza copper deposit, and there is a significant correlation between them. The content of Cu in surface soil of Duobuza copper mining area is especially rich, reaching 21 020.000×10-6, which is 50 times higher than the level Ⅲ standard in environmental quality standard for soil(GB 15618-1995);the comprehensive pollution index is 39.43, which reaches the heavy pollution level, the geoaccmulation indexes of most samples also reach the very strong pollution level, and the biological activity reaches a moderate risk level, and is easy to migrate and transform, which has a great impact on the environment. The maximum content of Cu in sediment of Samalong river bed is 2 406.000×10-6, which is 6 times of the level Ⅲ environmental quality standard for soil;the comprehensive pollution index is 38.13, the geoaccmulation index also reaches 91.6%, while it mainly exists in a more stable residual state(accounting for 42.83%), and RAC value is a low risk level, the migration ability is relatively weak, which has little impact on the environment, but the risk cannot be ignored;the content of Cd is not high, which is lower than the level Ⅲ environmental quality standard for soil, but it mainly exists in the carbonate bond state in river bed sediment(accounting for 48.01%), and the biological activity reaches an extremely high risk level, which has a relative great impact on the environment. The contents of Pb, Zn, As, Cr, Hg is generally low, and the biological activity is weak, which can exist stably in the soil, will not affect the environment basically. |
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| Keywords: | heavy metal element soil sediment speciation analysis geoaccmulation index comprehensive pollution index biological activity Tibet |
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