富汞植物的筛选及性能评价

发布时间：2018-07-23 09:43

【摘要】：汞作为全球性的环境污染物之一,它具有很高的毒性并且能够在环境中迁移,具有较大的环境风险且是全球污染治理的难题之一。目前,我国的汞污染也异常严重,因此寻求一种行之有效的治理方法至关重要。本论文针对我国汞污染的严峻现状,希望寻找到一种富汞能力强的植物。通过对福建德化某废弃金矿、北京石景山某钢铁厂和贵州万山废弃汞矿的采样调查,发现福建德化某废弃金矿的土壤汞浓度为117.01 mg·kg-1,北京石景山某钢铁厂的土壤汞浓度为2.85 mg·kg-1,而贵州万山废弃汞矿的土壤汞浓度为158.44～517.45 mg·kg-1,用单因子指数法评价方法得出三地均为重度污染。以植株中的汞含量、转运系数(TF)、富集系数(BCF)、生物量等指标作为富汞植物的筛选标准,最终从贵州万山废弃汞矿矿区筛选出了一种大量生存、长势良好、生物量大、汞含量高、转运系数大、富集能力强的富汞植物—鳞毛蕨科贯众。对筛选出来的富汞植物贯众在人工气候箱培养等实验室模拟条件下用氯化汞染毒的土壤进行盆栽实验。研究表明,贯众的耐汞浓度范围为0～500 mg·kg-1,其中贯众适宜的汞浓度为25～50 mg·kg-1。汞会对贯众的生理特性产生一定的影响而反映出贯众的抗胁迫能力的强弱。通过实验发现,贯众体内的超氧化物歧化酶(SOD)活性在汞浓度低时增加,汞浓度高时降低,随着时间的延长,超氧化物歧化酶(SOD)活性开始下降；贯众体内的谷胱甘肽(GSH)含量随汞浓度和时间的增加而增加；贯众体内的脯氨酸含量随汞浓度的增加先减小后增加,随着时间的延长脯氨酸的含量增加；丙二醛(MDA)含量随汞浓度和时间的增加均呈现增加趋势。贯众仍能正常生长,表明贯众的抗胁迫能力强。对老化和种植贯众后的土壤进行Tessier五步提取法形态分析,发现老化后土壤汞形态的大小顺序为离子交换态汞碳酸盐结合态汞有机结合态汞残渣态汞铁锰氧化物结合态汞,表明添加的氯化汞主要转化为离子交换态汞和碳酸盐结合态汞；种植贯众后的土壤离子交换态汞和碳酸盐结合态汞下降非常明显,表明贯众主要吸收离子交换态汞和碳酸盐结合态汞。通过实验发现弱酸性和少量有机质含量条件下有利于贯众吸收汞,碱性和过量的有机质含量则阻碍贯众对汞的吸收。其中,适宜的pH值范围为6.24～6.85,适宜有机质含量范围为1.79%～2.81%,通过L9(34)正交实验得出：(1)对贯众富汞影响最大的因素为汞浓度,其次为pH值,有机质的影响最小；(2)贯众的最优生长条件汞浓度为45 mg·kg-1, pH值为6.35,有机质含量为2.52%。贯众的富汞能力强,可以运用于工程实践进行检验。
[Abstract]:As one of the global environmental pollutants, mercury is highly toxic and can be transported in the environment. It has great environmental risks and is one of the global pollution control problems. At present, mercury pollution is very serious in China, so it is very important to seek an effective control method. In this paper, aiming at the serious situation of mercury pollution in China, we hope to find a plant with strong mercury rich ability. Based on the sampling investigation of an abandoned gold mine in Dehua, Fujian, an iron and steel plant in Shijingshan, Beijing, and an abandoned mercury mine in Wanshan, Guizhou, It was found that the mercury concentration in the soil of a abandoned gold mine in Dehua, Fujian Province, was 117.01 mg kg-1, that in a steel plant in Shijingshan, Beijing, was 2.85 mg kg-1, and that in the waste mercury mine in Wanshan, Guizhou Province, was 158.44 ~ 517.45 mg 路kg ~ (-1), respectively. A single factor index method was used to evaluate the mercury concentration in the soil. The three places are all heavily polluted. With mercury content, transport coefficient (TF), enrichment factor (BCF) and biomass in plants as screening criteria, a large amount of survival was selected from the abandoned mercury mine area in Wanshan, Guizhou Province, with good growth, large biomass and high mercury content. The mercury-rich plant, Dryopteridaceae, has large transport coefficient and strong enrichment ability. Pot experiments were carried out on selected mercury-rich plants in laboratory simulated conditions such as artificial climate chamber culture and so on. The results show that the concentration range of tolerance to mercury is 0 ~ 500 mg 路kg ~ (-1), and the suitable concentration of mercury is 25 ~ (50) mg 路kg ~ (-1). Mercury has a certain effect on the physiological characteristics and reflects the ability of resistance to stress. It was found that the activity of superoxide dismutase (SOD) increased when mercury concentration was low and decreased when mercury concentration was high. With the prolongation of time, the activity of superoxide dismutase (SOD) began to decrease. The content of glutathione (GSH) increased with the increase of mercury concentration and time, and the content of proline decreased first and then increased with the increase of mercury concentration, and the content of proline increased with the increase of time. The content of malondialdehyde (MDA) increased with the increase of mercury concentration and time. Guanzhong can still grow normally, indicating that Guanzhong has a strong ability to resist stress. Tessier five-step extraction method was used to analyze the speciation of aged and cultivated soils. It was found that the order of mercury speciation after aging was ion exchange mercury, carbonate-bound mercury, residual mercury-ferromanganese oxide mercury-bound mercury. The results showed that the added mercuric chloride was mainly converted into ion exchange mercury and carbonate bound mercury, and the soil ion exchange mercury and carbonate bound mercury decreased obviously after planting. It is shown that ion exchange mercury and carbonate bound mercury are mainly absorbed by Guanzhong. It was found that weak acidity and a small amount of organic matter were beneficial to the absorption of mercury, while alkaline and excessive organic matter content hindered the absorption of mercury. Among them, the suitable pH range is 6.24 ~ 6.85, and the suitable organic matter content range is 1.79 ~ 2.81. Through L9 (34) orthogonal experiment, it is concluded that: (1) the concentration of mercury is the most important factor, the next is pH value, and the influence of organic matter is the least; (2) the optimum growth conditions were mercury concentration of 45 mg kg -1, pH value of 6.35 and organic matter content of 2.52%. The mercury-rich ability is strong and can be tested in engineering practice.
【学位授予单位】：北京化工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X53;X173

【参考文献】