【作者】 董霁红；

【导师】 卞正富；

【作者基本信息】 中国矿业大学 ， 环境科学， 2008， 博士

【摘要】 矿区土壤重金属污染及其修复是当今矿山生态及我国区域性、行业性领域的研究热点,对土地可持续利用、粮食安全、矿区环境与区域生态保护具有重要意义。通过对矿区充填复垦土壤进行系统、量化的野外及实验室研究,所得出的理论方法、数学模型、试验技术、相关数据、软件手段等可为国家指导矿区土地复垦和生态重建提供数据支持和科学指导,并可为相关矿区环境政策的制定提供参考。本文在较系统地综述了国内外矿区复垦土壤研究进展情况的基础上,重点开展了五方面的研究工作:1.充填复垦土壤特性场地实测与室内实验相结合,系统地研究了复垦土壤的理化、生物特性,包括土壤的渗透性、紧实度、孔隙水电导率、含水率、温度、pH值、有机质、氮磷钾、重金属、微生物(细菌、真菌、放线菌)种类种数;选用美国2800K1型渗透仪、英国三参数速测仪HH2/WET、美国紧实度仪soil compaction,测试分析了土壤的紧实度等。数据结论:煤矸石、粉煤灰充填(覆土厚度40cm)复垦土壤的pH值为7.98-8.78,含水率高于正常土壤10%-20%,渗透性系数为0.059-0.286,紧实度在200-300PSI,有机质含量低于对照土壤。这些研究结果对于国家制定矿区复垦技术标准及复垦工程的设计实施具有重要的参考价值。2.复垦土壤重金属分布规律研究了矿区充填复垦土壤重金属污染问题,首先探讨了充填复垦区域土壤重金属空间分布特征分析的理论与方法,通过采集、处理、测试245个土样的As、Cd、Cr、Cu、Hg、Pb、Zn等的含量,利用变化度、污染度和含量趋势等指标,解析研究了煤矸石充填复垦土壤、粉煤灰充填复垦土壤、对照土壤三类土壤的重金属分布特征;在此基础上,总结了七种元素的空间分布情况,对严重污染的Cd、轻度污染的Cr、正常范围的Pb进行了重点分析;采用线性、对数、指数、乘幂、多项式、克里格模型阐释了Cd、Cr及Pb的空间分布规律,得出结论:①简单模型:拟合的模型在一定程度上能反映出微量元素的变化趋势,三块场地模型拟合的误差均值保持在30%以内,其中,煤矸石场地误差最小,最大值为18.4%,最小值为8.3%;②多项式模型:由反演所得数据绘制的模拟迁移图具有现实应用意义,即可利用模型由测点的数值推知未测点的数值,得到相对连续的重金属含量值,分析其空间分布规律;③Kriging模型:以粉煤灰场地的Cd为例,建立的模型拟合精度较高。上述研究结果将为矿区污染土地的修复并进而制定相应治理措施提供依据。3.土壤特性与重金属污染相关性的方法与理论首先确定了可能影响土壤重金属分布的四个重要土壤特性:土壤紧实度、土壤pH值、土壤有机质以及土壤微生物;采用Pearson Correlation Coefficient方法,分析了pH值对重金属分布的影响、有机质与重金属分布的相关程度、紧实度与重金属污染的关系、微生物与重金属污染的相关性,结果表明:①充填复垦场地的pH值、有机质和紧实度与重金属含量的相关性较弱,相关系数都在-0.6到0.6之间,这也说明了在一定程度上,重金属空间分布的无规律性。②微生物与土壤重金属的相关性很大,在粉煤灰场地体现的更加明显,微生物的多少对土壤重金属含量产生直接的影响;最后应用集对理论(Set Pair Analysis Theory)研究了微生物与重金属的关联机理。这对于深入认识土壤重金属迁移机理的复杂性具有重要的科学意义,并可为其中难以定量和难以鉴别的污染相关因素的后续研究提供数据支持。4.主要农作物重金属污染物迁移规律研究比较研究了世界主要国家和地区对小麦、水稻和大豆中重金属污染物的限量标准,提出了小麦等主要农作物重金属污染物限量的选取标准;采用单项、综合污染指数分析了根际土壤As、Cd、Cr、Cu、Hg、Pb、Zn的污染状况,得出了复垦土壤综合污染指数小于1,全部测点均达到了土壤环境质量二级标准要求;定量解析了小麦不同部位的重金属含量,确定Cd、Cr为污染元素,研究结果:①复垦场地生长的成熟小麦,Cd、Cr在其不同器官中的分布迁移趋势是一致的;②对照场地生长的成熟小麦,Cd、Cr在其不同器官中的分布趋势存在差异;提出根富集系数率,进行曲线估计,建立了Cd回归方程、Cr偏微分方程。这些研究结果对矿区粮食安全的监控具有重要的实际应用价值。5.土壤、作物污染程度的可视化表达探索性地引入Surfer软件成图方法,借助多项式模型反演所得的数据,对矿区复垦土壤的结构进行可视化,直观地描述了土壤重金属分布的纵向、横向特征;应用Photoshop软件,对主要农作物小麦中重金属的污染迁移,以Cd、Cr为例,制作了量化模拟色彩映射图,真实地评价了小麦不同器官中重金属的污染程度。更多还原

【Abstract】 The study on soil heavy metals pollution and its rehabilitation in mining area is the present focus on mine ecology or the territorial and industrial fields in China. It is provided with great importance to sustainable land use, food security, mining area environment, regional entironment protection and so on. After the systemic, quantized field or laboratorial research of the filling reclamation soil in mining area, theoretical method, mathematical model, experiment techniques, relevant data, software measure and some other achievements were made. They offered the data support and scientific guidance for the state to supervise the land reclamation and ecological construction in mining area, also offered the reference for making related environment policy of mining area.Systematically summarized the development of research at home and abroad on reclamation soil in mining area, this paper focuses on the following five research works:1. Research on filling reclamation soil characteristicsReclamation site observation combined with indoor experiment, the physical, chemical and biological characteristics of filling reclamation soil had been systematically studied, concretely including the permeability, compaction, pore-water conductivity, water content, temperature, pH value, organic matter, nitrogen-phosphorus-kalium, heavy metals, microorganism (bacteria, fungi and actinomyces) species or kinds; Soil compaction had been tested and analyzed using the 2800K1 Guelph---permeability testing machine made in America, W.E.T Sensor Kit---the British three-parameter rapid measure instrument HH2/WET, the American compactness meter. The data conclusions includes: the pH of both the coal-fly-ash and coal-gangue filling reclamation soil (cover soil thickness is 40cm) is between 7.98 and 8.78; the soil water content is 10%-20% higher than natural soil; the permeability coefficient varies from 0.059 to 0.286; the soil compaction is between 200 PSI to 300PSI; organic matter content is lower than natural soil. To sum up, the index values of filling reclamation soil’s physical and chemical properties are within the normal area of natural soil, and have no obvious difference. These outcomes have significant reference value to the state for making land reclamation technical standards and to designing and implementing of the reclamation project.2. Research on the distribution of reclamation soil heavy metals The problems about filling reclamation soil heavy metal pollution in mining area were brought forward. Firstly, the research went on the theoretics and methods used for analyzing heavy metal’s spatial distribution characteristics in filling reclamation area. Two hundreds and forty five soil samples were collected and processed, and then the heavy metal concentrations of the soil samples, such as As, Cd, Cr, Cu, Hg, Pb, Zn and others were determined. For three kinds of the soil heavy metals, coal-gangue filling reclamation soil, coal-fly-ash filling reclamation soil and natural soil for comparison, the author analyzed and studied theirs distribution by varying multiple, contamination degree and concentrations trend. Based on these, the distributions of seven elements were summarized, and Cd arisen severe pollution, together with Cr arisen slight pollution and Pb in normal were emphatically analyzed. Expounding the spatial distribution of Cd, Cr and Pb by linearity, logarithm, index, power, polynomial, Kriging and other mathematical models, conclusions were made as follows:①Simple model: to a certain degree, the fitted model can figure out the change tendency of microelements, all the grand means of model fitted error of the three sites kept within 30%, thereinto, the site error of coal gangue was the least, and the maximum is 18.4% while the minimum is 8.3%.②Polynomial model: Making the analog transition diagram by the data inverted has practical meaning. The numerical value of unmensurated points can be deduced from mensurated points using models, and then gained the correspondingly seriate heavy metal contents, the spatial distributions can be analyzed.③Kriging model: The built models have high fitting precision, taking Cd of coal-fly-ash site as an example. The research results above will provide foundations for rehabilitating the polluted land in mining area and then setting corresponding govern measures.3. Methods and theoretics about the relativity between soil characteristic and heavy metal pollutionThe four important specialties like to effect on soil heavy metals distribution were ascertained first: soil compaction, the pH of soil, soil organic matter as well as soil microorganisms; employing in the Pearson Correlation Coefficient method, how pH affects the distribution of heavy metal, the correlation degree between organic matter and the distribution of heavy metal, the connections between compaction and heavy metal pollution, along with the relevancy between microorganism and heavy metal pollution were analyzed; The data results show that:①The soil pH, soil organic matter and soil compaction of the filling reclamation site all only have slight relativities with heavy metals, and relativity coefficient are amongst -0.6 and 0.6. To a certain extent, this also account for that the spatial distribution of heavy metals has no regularity.②Soil microorganisms have quite high relativity with soil heavy metals, and this presents much more obvious for a coal-fly-ash site. The quantity of microorganisms has a direct effect on the heavy metal content of soil. Finally, the relationship mechanism between microorganisms and heavy metals was studies by the application of Set Pair Analysis Theory. This has concernful scientific significance for in-depth understanding the complexity of soil heavy metals’migration mechanism, and also can afford definite data support for the further study on the factors related to pollution which difficult to quantify or distinguish.4. Research on heavy metal pollution migration of main cropsInvestigated and compared the Limit Standard of the heavy metal contaminations in wheat, rice and soybeans in primary countries and regions in the world, the selection standards of the heavy metal contaminations quota in wheat and other main crops were advanced. The rhizospheric soil’s pollution situations of As, Cd, Cr, Cu, Hg, Pb and Zn were analyzed by single contamination index method, also comprehensive contamination index method. It is concluded that comprehensive contamination index of reclamation soil was less than 1, and all the observation points reached to the secondary standard requirements of soil environment quality. The heavy metals content of wheat’s different parts were quantitatively parsed, and confirmed Cd and Cr as contaminations. The followings are the research results:①The distributions and migration tendencies of each different parts of the mature wheat growing on reclamation sites is in consistent.②There are differences in the distributions and migration tendencies of each different parts of the mature wheat growing on control sites. Root enrichment coefficient ratio was put forward, and curve estimation was done, and Cd regression equation and Cr partial differential equation were established. These research outcomes are provided with important practical value for monitoring the food security in mining area.5. Introduction of the description technique with the software of Surfer and PhotoshopExploringly introducing the software Surfer to produce map, using refutations data from polynomial model, we visualize the reclaimed soil structure of mining area, and intuitively described the vertical and horizontal distribution features of heavy metals in the soil; using the software Photoshop, taking Cd and Cr for example, we produced a quantitative simulation of color mapping maps to describe the migration of heavy metals pollution in the main crops wheat, and obtained a reliable evaluation of the heavy metals pollution levels in different organs of wheat.更多还原