【作者】 李海英；

【导师】 顾尚义；

【作者基本信息】 贵州大学 ， 环境工程， 2007， 硕士

【摘要】 矿山开发引起的环境问题是一个世界性的问题，国内外许多学者对此做了大量研究。如矿山尾砂在风化过程中有害物质（如重金属）释放，酸性矿山废水的产生及其危害性等，都有了相当深入的探讨，相比较而言对于Pb、zn冶炼（特别是土法炼锌）引起的环境问题探讨较少。贵州黔西北是我国著名的土法炼锌基地，其土法炼锌历史悠久，产生的黑色烟尘，含有大量铅、锌、镍、镉、硫和一氧化碳，对人体和农作物都有非常大的危害。土法炼锌产生的废渣未通过任何处理直接堆放，对当地生态环境造成了极其严重的污染。因此本文通过在野外调查、勘测、采样分析的基础上，对黔西北土法炼锌的污染状况进行了初步的调查评价，在此基础上进行实验室栽培试验研究，以磷肥作为改良剂，以玉米作为试验栽培植物，探讨了不同磷肥配比对铅锌冶炼废渣中重金属的固化作用，根据其上玉米作物的生长状况，探索铅锌冶炼废渣场复垦的优良措施，本次试验取得结果如下：1、黔西北土法炼锌矿区土壤中重金属都有不同程度的积累，其中土壤中Zn为261.39—1647.29mg／kg；Cd为3.47—18.32mg／kg；Pb为128.72—941.75mg／kg；Cu为19.09—267.59mg／kg；As为13.73—39.32mg／kg，根据土壤环境质量标准，矿区周围土壤中重金属元素已经大大超过了贵州土壤背景值，中国A层土壤含量以及世界各国土壤中重金属含量限制，矿区土壤已受到重金属元素的严重污染；矿区废渣中重金属除Cu外，其余重金属含量都严重超标，是当地严重的污染源。矿区植物体内各种重金属都有不同程度的积累，植物Zn为31.56—340.49mg／kg；Cd为0.61—13.94mg／kg；Pb为1.10—64.42mg／kg；Cu为3.51—32.34mg／kg；As为0.04—2.09mg／kg。2、环境影响评价结果表明：土法炼锌矿区除个别土壤属于中度污染外，其余全部处于严重污染状态；土法炼锌矿区周围所种植蔬菜全部已受到严重的污染，综合污染指数在10.83—40.67之间，主要以Cd为主，超过国家蔬菜标准高达54倍；矿区周围其他植物玉米和紫花苜蓿等中的重金属亦严重超标，主要以Pb污染为主，超过国家粮食标准高达366.75倍；这对当地的居民的生活造成了很大的威胁。3、盆栽试验纯渣中重金属含量很高，和土壤按照1：1比例混合后，其配比中重金属含量降至一半左右。盆栽不同配比中重金属含量对玉米的发芽率没有多大影响，而对于玉米株高和鲜重有很大的影响，表现出明显的抑制现象。4、纯渣中生长的玉米茎叶中重金属含量很高，而且大大超过了国家食品卫生标准。按照各配比改良后，玉米茎叶中的重金属含量有所下降，Zn、Cd和Cu三种重金属都在配比K₄（15 mg／kg P）出现了玉米茎叶中浓度含量最低点，而Pb在K₅（17.5 mg／kg P）配比时，玉米茎叶中浓度含量最低。与玉米茎叶中含量变化恰好相反，根中各种重金属含量在K₁（5 mg／kgP）配比出现了浓度最低值，而在K₄（15 mg／kg P）和K₅（17.5 mg／kg P）配比，玉米根中重金属含量反而增加。综合考虑四种重金属在玉米中的累积状况，磷肥配比在15——17.5 mg／kg范围内可能对重金属的固定效果较好。5、不同种植时间对玉米中重金属含量都有很大的影响。生长50天后，玉米中各种重金属含量明显低于生长20天玉米茎叶中重金属含量。6、不同磷肥配比处理对土壤中有效态重金属含量有很大的影响，其变化随着配比的逐渐升高，土壤中有效态重金属（Zn、Cd和Cu）含量呈现出降低——升高的趋势，在K₃配比点出现的最低浓度值，这对以后的进一步研究提供了可靠的基础。但是Pb呈现出相反的变化趋势。7、总体来说，磷肥配比在10 mg／kgP——17.5 mg／kgP范围内对废渣中重金属的固定效果较好。更多还原

【Abstract】 The environmental problem resulted from ore minerals development is a global concern and have accepted much attention in the world. So far, a lot of researches focused on the release of hazardous substances （such as heavy metals） in mine tailings during the weathering process, the production of acid mine drainage and its threat to environment. Nevertheless, the research for environmental problems caused by Pb, Zn smelting （especially historical Pb-Zn smelting） slag is less. The Northwestern Guizhou Province is a famous place for its long history in Pb-Zn smelting. The Mack dust omitted by Pb-Zn smelting contains large amounts of lead, zinc, nickel, cadmium, sulfur and carbon monoxide, which has a potential risk to human beings and crops. The historical Pb-Zn smelting slag has caused an extremely serious pollution to the local ecological environment without any treatment adopted. On the basis of field investigation, sampling, and analyses for heavy metals contents in contaminated soils, pollution situations in soils contaminated by Pb-Zn smelting were presented and maize pots experiment were conducted with phosphorus fertilizer as remediation media in different slag to soil ratios. According to the maize pots experiment results, some concluding remarks have been made as are as follows :1. Historical Pb-Zn smelting slag land in Northwestern Guizhou Province have been contaminated by heavy metals in varying content., which soil Zn between 261.39 to 1647.29 mg/kg; Cd between 3.47 to 18.32 mg/kg;Pb between 128.72 to 941.75 mg/kg; Cu between 19.09 to 267.59 mg/kg;As between 13.73 to 39.32 mg/kg. According to Environmental quality standard for soils （GB15618-1995）, heavy metals in the soil around the Pb-Zn smelter have greatly exceeded soil back -ground values in Guizhou Province, contents of layer A in average Chinese soil, and contents of average soils over the world. Soils around the historical Pb-Zn smelters has been seriously polluted by heavy metal.2.The results of environmental impact assessment indicate that soils and vegetables grown on the soils have been seriously polluted by heavy metals, especially Cd, except the soil in Yemachuan of Hezhang County being moderately polluted. This has a potential threat to health of human beings and plants around the Pb-Zn smelters.3. Mixing soil with slag in the ratio of 1:1 in pots did not affected the maize germination rate too much, but greatly inhibited growth of the maize by lowering plant height and weight.4. The maize grows in pure slag have high content of heavy metals in its leaves, and significantly exceeded the national food hygiene standards. In accordance with the ratios conducted, the contents of heavy metals in maize leaves has declined, Zn, Cd, and Cu in leaves of maize have been lowest concentrations in the ratio of K₄ （15 mg/kg P）, and Pb in K₅ （17.5 mg/kg P） ratio. On the contrary, the lowest concentrations for roots of various heavy metals is in K₁ （5 mg/kg） ratio, but have the high concentration of value in K₄ （15 mg/kg P） and K₅ （17.5 mg/kg P） ratio. Considering four heavy metals in the cumulative maize situation, phosphorus ratio in 15--17.5 mg/kg is suitable to immobilizing heavy metal transported from soils to plants.5. Different growth periods have greatly affected the heavy metals contents of maize. The contents of heavy metals in maize leaves in growth period of 50 days were lower than 20 days.6. Amounts of phosphorus fertilizer adding to pots have significant impact on the content of available heavy metals in soils. The available Zn, Cd, and Cu contents show the trend of ascending first, descending second, and ascending again along with increased phosphorus fertilizer addition. This provides a reliable basis for further study. But Pb showed the opposite trend. Therefore, it is difficult to control heavy metal composite pollution by simply adding soluble phosphate to contaminated soil.7. In general, the phosphorus ratio between 10ppm to 17.5ppm is better to reclaim soils contaminated by heavy metals.更多还原