酸模叶蓼锰富集特性研究及同步辐射表征

【作者】 田守祥；

【导师】 何哲祥； 薛生国；

【作者基本信息】 中南大学 ， 环境工程， 2010， 硕士

【摘要】 锰矿开采和冶炼过程形成大量的矿冶废弃地,对当地的大气、土壤、水体造成严重污染。超积累植物因其超寻常的重金属积累能力而被广泛应用于污染环境修复。因此,筛选生物量大、生长快、地理分布广,适应性强的锰超积累植物,并深入探讨植物的锰超积累机理,是开展锰污染环境植物修复的关键科学问题。但对于锰超富集植物而言,种质资源相对较少,相关研究大多停留在野外植物筛选阶段。本研究旨在对湖南湘潭锰矿废弃地系统调查的基础上,筛选新的锰超富集植物,进一步扩充重金属超富集植物种质资源库。这对于金属矿区废弃地的生态恢复及重度污染土壤的修复具有重要的理论意义及应用价值。采用野外踏查法,系统调查了湘潭锰矿区域的植被状况及乡土植物,并对植物样品进行元素含量分析,发现了一种新的具有超富集潜力的锰耐性植物——酸模叶蓼。通过酸模叶蓼温室培养,并对收集的样品进行电感耦合等离子体发射光谱仪测定元素含量。结果表明：不同锰供应条件下,酸模叶蓼均能正常生长,即使在生长介质锰含量高达10000μmol·L-1时,酸模叶蓼仍然能够完成整个生命周期,这表明酸模叶蓼有较强的锰耐性,有应用植物稳定技术修复锰污染环境的潜力。酸模叶蓼不同器官组织对锰的吸收存在差异性,叶对锰的积累最强,其次是根、茎。随着生长介质中锰供应水平的升高,根、茎和叶锰含量均呈增加态势。叶片是酸模叶蓼富集锰的主要器官,5000μmol·L-1、10000μmol·L-1锰处理条件酸模叶蓼叶锰含量分别达18709mg·kg-1、27663 mg·kg-1(干重)而生长正常,并未出现锰毒症状。不同锰处理条件下,酸模叶蓼吸收的Ca、Mg、Fe、Cu、Zn变化不显著,未表现出营养元素缺乏的现象,这可能是出于酸模叶蓼对高锰生境条件的一种反馈机制。进行傅立叶变换红外光谱分析,结果表明：酸模叶蓼叶中各基团吸收峰中仅有1380cm-1处的含油脂化合物(各种膜和胞壁)的组织中甲基的吸收带随锰处理浓度的增加呈现先增加后减小的趋势,峰形也多向短波位移。这表明随着Mn浓度的升高,细胞壁通过降低果胶甲基化程度,使阳离子交换能力提高,从而吸收更多的Mn,即通过细胞壁中积累Mn来增强抗逆性,但高浓度的Mn已对酸模叶蓼产生了胁迫,甲基化程度又开始升高。这可能是由酸模叶蓼积累的锰积累在植物细胞壁及膜中对其组织产生的胁迫。通过同步辐射XAFS光谱分析发现,与有机酸结合是锰在酸模叶蓼叶片内的主要存在形态,锰处理会改变叶片内锰的形态：对照条件下,锰在酸模叶蓼叶片内主要是以柠檬酸结合态和谷胱甘肽螯合态存在;低锰处理条件下,酸模叶蓼叶片内的锰则主要是苹果酸锰、单质锰、谷胱甘肽锰；高锰处理条件下,苹果酸锰是锰在酸模叶蓼叶片内的主要存在形态。对植物样品进行同步辐射硬X射线光谱分析发现：不同锰处理对酸模叶蓼叶锰及其它元素微区分布产生影响。对照条件下,锰在叶上的分布相对比较均匀；随着锰处理浓度的增加,酸模叶蓼叶片积累的锰趋向于叶脉处积累,K、Fe、Cu、Zn等元素在叶片的分布随着锰处理浓度的变化与锰类似。更多还原

【Abstract】 Lots of mining wasteland form after manganese mining and smelting, which pollute heavily environment. Phytoremediation attracts interest and attention from governments and enterprises as a potentially cost-effective, engineering-economical and green technique to clean up heavy metal-polluted soil. Accordingly, exploring the mechanism of manganese tolerance and hyperaccumulation is important to find new manganese hyperaccumulator plant which grows rapidly and has substantial biomass, wide distribution and broad ecological amplitude. But the hyperaccumulators is less, most of reasch still stay in stage of the wild plants screening.The purpose of this study is to expand the germplasm banks of heavy metal hyperaccumulators by screening new hyperaccumulator on the basis of investigation of Xiangtan manganese tailings wastelands. It has important theoretical significance and application value for the metal ecological restoration and pollution control of soil.The native vegetation and plants in Xiangtan manganese mining area were investigated. It was found that Polygonum lapathifolium L has super manganese patience.Under the condition of different manganese supplying, even the manganese concent is 1OOOOμmol·L-1, Polygonum lapathifolium L can grow normally. This implies that Polygonum lapathifolium L have strong manganese patience. The distribution of manganese among roots, stems and leaves in Polygonum lapathifolium L is different. The ICP-OES analysis reveals that the levels of Mn in roots, stems and leaves of the plants increase while the content of Mn2+ increasing in the culture solution. The results show that Mn distribution sequence is: leaves>roots>stems. And most of Mn is transferred and accumulated in leaves. When the Mn content of culture solution is 5000μmol·L-1,10000μmol·L-1, the Mn content of leaves reaches 18709mg·kg-1,27663mg·kg-1 respectively. There is no nutrient element deficiency. This may be Polygonum lapathifolium L’s feedback mechanism at high manganese contents.Leaves FTIR curves indicates there is only methyl groups’characteristic absorption peaks(1380cm-1) in various cell membrane and wall have changes:peak height increase at first, and then decrease with the increase of concentration of manganese processing, Simultaneously, the peak also slightly moves toward the shorter wavelength. This shows the cell wall increases cation exchange absorbs even more Mn through decreasing its methylation levels, but the high content of Mn has stressed on Polygonum lapathifolium L, and then methylation began to rise.Synchrotron radiation XAFS spectra show that manganese treatment could change its form in the leaf of Polygonum lapathifolium L. In contrast condition, the manganese in the leaves of Polygonum lapathifolium L is mainly in the form of manganese, citric acid and tathion. In low manganese processing conditions, manganese in the leaf of Polygonum lapathifolium L is mainly in the form of malic acid manganes, elemental manganese and glutathione manganese. In high manganese processing conditions, manganese in the leaf of Polygonum lapathifolium is mainly in the form of malic acid.Different manganese processing can affect the distribution of manganese and other elements. Synchrotron radiation hard X-ray spectra showed that the distribution of manganese in the leaf is relatively homogeneous in the control condition. With increasing manganese content, manganese in the leaf of Polygonum lapathifolium L tends to accumulate in veins, and the distribution of other elements in leaves is similar to manganese.更多还原