【作者】 杨金香；

【导师】 张明旭； 姚多喜；

【作者基本信息】 安徽理工大学 ， 环境工程， 2012， 博士

【摘要】 植物修复是近年来发展起来的土壤重金属污染整治的重要手段之一,受到国内外众多学者的关注。本文基于淮南煤矿复垦区的复垦特点,选取大通生态湿地(Datong ecological wetland, DTEW)-.潘一矿复垦区(Panyi mine reclamation area, PYRA)和新庄孜矿复垦区(Xinzhuangzi mine reclamation are, XZRA)为研究对象,分析研究了复垦区土壤重金属污染特点,表明复垦区土壤受到重金属元素的不同程度污染,其中Cd是复垦区土壤重金属污染最主要的诱发因子。在此基础上,筛选不同树种的木本植物,通过趋势模拟与数学建模,探寻重金属在煤矸石—土壤—木本植物系统中的迁移规律。(1)通过不同复垦区内同种木本植物对不同重金属的吸收富集能力的研究,表明复垦类型的不同,同种植物发生了不同种群之间的差异和分化,形成了不同生态型,从而影响了同种木本植物对同种重金属的吸收积累能力差异。(2)根据不同复垦区内不同时间段采集的复垦煤矸石中的重金属含量,通过趋势分析,探寻煤矸石在覆土状态下重金属释放规律。结果表明覆土状态下煤矸石重金属元素释放规律遵循负指数方程,且以木本植物修复为主的复垦区内煤矸石中重金属释放速率大于以草本植物修复为主的煤矸石中重金属的释放速率,证明了植物根系能够加速复垦煤矸石中重金属元素的释放。(3)通过覆土底层土壤中重金属与复土厚度、pH、含水率、总孔度、有机质、速效钾、速效磷和CEC等影响因子的相关性分析,确定主要影响因子,采用多元线性回归,移除异常因子,建立了煤矸石—上层覆土界面之间不同重金属迁移影响因子模型。(4)根据木本植物根系吸收、富集土壤中重金属的特点,提出了新的采样布点方案,以探寻重金属在土壤—根区系统中的迁移规律。结果表明：木本植物根系对重金属吸收富集能力强,其迁移能力就较强,且迁移规律沿着根系遵循三次曲线模型；随着根系对重金属的吸收富集能力降低,其迁移能力也逐渐降低,且迁移规律沿着根系由三次曲线模型向直线模型趋势过渡。同时采用克里格方法,建立了具有植物富集特点的不同范围内不同剖面的克里格模型。并通过大量的土壤与木本植物中重金属含量数据,采用趋势拟合的方法,发现重金属在根际土—根区,以及在木本植物系统的分布规律遵循三次曲线模型：y=a3X3＋a2x2＋a1x＋a0,。(5)依据木本植物从复垦区土壤中吸收和富集重金属的过程,结合重金属在木本植物体内的积累机理,细化木本植物的生理结构特点,运用药物动力学的“房室模型”思想,建立了木本植物吸收、富集重金属的二室、三室数学模型,以及茎杆的时空模型,即：二室模型：(由土壤进入根系的速率为常数)；(土壤中重金属含量为定值)；三室模型：茎杆的时空模型：(6)论文从采样方法上,根据木本植物根系吸收、富集土壤中重金属的特点,提出了一种确定土壤中重金属迁移趋势的方法和系统。并针对煤矿复垦区特点,系统、全面地探讨了煤矸石—土壤—木本植物系统中的重金属迁移规律,运用药物动力学的思想,从理论上构建了重金属在木本植物系统的迁移模型,从而为定量研究重金属在木本植物系统中的迁移、积累过程和定量计算模型的合理选择提供思路和方法。更多还原

【Abstract】 Phytoremediation, which had been developed in recent years, was one of the important means of regulating the soil heavy metal pollution, and it had been paid attention to by many scholars at home and abroad. Based on the reclamation characteristics of coal mine reclamation areas in Huainan, the thesis selected Datong ecological wetland (DTEW), Panyi mine reclamation area (PYRA) and Xinzhuangzi mine reclamation area (XZRA) as the research objects and analyzed as well as studied the pollution characteristics of soil heavy metals in reclamation areas. It showed that the soil in reclamation areas was contaminated by heavy metals in different degrees and that Cd was the main inducing factor of soil heavy metal pollution in reclamation areas. On the basis, the thesis, sifting through different species of woody plants, researched the migration law of heavy metals in the coal gangue-soil-woody plants system by means of the trend simulation and mathematical modeling.(1) Through the research on the ability of the woody plants in different reclamation areas to absorb and accumulate different heavy metals, it showed the type differences of reclamation. The differences and differentiation occurring among different species happened among the same species, and the different ecotypes were formed, which affected the ability of the same woody plants to absorb and accumulate the same heavy metal.(2) According to the content of heavy metals in gangue collected at the different time in different reclamation areas, the thesis, through the trend analysis, studied the desorption law of heavy metals in gangue under the covering soil. The findings revealed the desorption law in this situation followed the negative exponential equation, and they showed the desorption rate of heavy metals in gangue in reclamation areas mainly repaired by woody plants was higher than that of heavy metals in gangue in reclamation areas mainly repaired by herbaceous plants. It proved that plant roots could accelerate the desorption of heavy metals in gangue in reclamation areas.(3) Through the analysis of the correlation between heavy metals in the underlayer covering soil and the covering soil thickness, pH, water content, hole degree, organic matter, available potassium, available phosphorus as well as cation exchange capacity, the thesis determined the main factors. Adopting the multiple linear regression, the thesis removed abnormal factors, and it established the influence factor migration models of different heavy metals in the system of gangue and the upper covering soil, such as Cd, Cu, Mn and Pb.(4) According to the characteristics of woody plant roots in absorbing and accumulating heavy metals in the soil, the thesis put forward a new sampling scheme in order to study the migration law of heavy metals in the soil-root interface system. The findings could be revealed in the two aspects. On one hand, if the ability of woody plants to absorb and accumulate heavy metals was great, their migration ability was great accordingly, and the migration law followed the cubic curve model along the roots; if the ability of this kind was reduced with roots, their migration ability was gradually weak as well, and the migration law made the transition from a cubic curve model to a linear model. At the same time, the thesis, using the Kriging method, established Kriging models with different profiles at different stages, which had the characteristics of plant accumulation. Through a large number of heavy metal content data in the soil and woody plants, the thesis, using the trend fitting approach, found that the distribution law of heavy metals in the rhizosphere soil-the root zone as well as in the woody plants system followed a cubic curve model:y=a3X3+a2X2+a1x+ao.(5)According to the process during which woody plants absorbed and accumulated heavy metals in the reclamation areas, the thesis, combined with the accumulation mechanism of heavy metals in woody plants, refined the physiological structure characteristics of woody plants. By using the thought about the pharmacokinetic compartment model, it established a two-compartment mathematical model and a three-compartment mathematical model reflecting how woody plants absorbed and accumulated heavy metals, and it built the space-time model about stems as well. They were as follows:Two-compartment mathematical model:Note: The migration rate of heavy metals (The rate at which heavy metals migrate from the soil to the roots was a constant).Note: The content of heavy metals in soil was a fixed value. Three-compartment mathematical model: Space-time model about stems:(6) According to the characteristics of woody plant roots in absorbing and accumulating heavy metals in the soil, in terms of methodology, the thesis brought forth a method and system for determination of heavy metals migration trends in soil. Based on the characteristics of the coal mine reclamation areas, it fully and systematically discussed the migration law of heavy metals in the gangue soil-woody plant system, and it, using the thought about pharmacokinetics, established a migration model of heavy metals in the woody plants system theoretically, thus providing ideas and methods for the quantitative study of the migration and accumulation of heavy metals in woody plants system as well as the reasonable selection of the quantitative calculation models.更多还原