【作者】 薛生国；

【导师】 陈英旭；

【作者基本信息】 浙江大学 ， 环境工程， 2005， 博士

【摘要】 锰是人类和动物必需的微量元素,然而摄入过量的锰,则引起锰中毒,主要表现为类帕金森氏综合症,也对生殖系统、免疫系统和心血管系统产生异常反应。锰在工农业方面广泛使用以及锰矿开采已造成大面积土壤、地表水和地下水的锰污染。超积累植物是一种极端的金属积累型,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。通过对位于湖南省湘潭锰矿污染区的植物和土壤进行了一系列的野外调查,在中国首次发现商陆对锰具有明显的超富集特性,填补了我国锰超积累植物研究的空白。将野外调查和温室培养相结合,以不同种群商陆为材料,综合运用扫描电子显微镜技术、透射电子显微镜技术、X射线能量分散谱技术、扩展X射线精细结构分析、电感耦合等离子体原子发射光谱仪、高效液体色谱技术、高速离心技术等分析手段较系统研究了商陆的锰耐性及超富集特性及其可能的生理机制,并考察其对Mn、Cd、Zn的去除能力,以期为重金属污染环境修复和人工湿地植物筛选提供理论依据。通过研究取得以下主要结果:商陆(Phytolacca acinosa Roxb.)对生长介质中的Mn具有极强的耐性和超富集能力,是一种生物量大、生长快、适应性强的锰超积累植物。商陆在锰含量高达114000 mg/kg的尾矿废弃地上依然生长良好,叶锰含量最高达19300mg/kg。温室培养条件下,当生长介质中Mn含量为8000μmol/l时,虽然其生物量与对照相比有所降低,但植株仍能生长。随着生长介质中Mn浓度的升高,商陆叶和茎的Mn含量逐渐增加,生物富集系数则逐渐降低,但是地上部分锰积累量则先增加后减少。当Mn浓度为5000 μmol/l时,商陆地上部分锰积累量达到最大值258. 2 mg/plant;当Mn供应水平达到12000 μmol/l时,商陆仍能完成整个生命周期,叶锰含量达到最大值36380 mg/kg,生物富集系数为55。不同锰供应水平下,商陆吸收的锰有87%-95%被转移到地上部分。商陆的锰耐性和超积累能力可能是其固有特性。 尽管不同种群商陆在自然检摘要叼岁条件对生长介质中Mn的积累量存在显著差异,但是在控制条件下都能忍耐高锰胁迫,具有很强的锰积累能力,而且不同种群之间没有显著差异。商陆在不受污染的荷花玉兰人工林中叶片锰含量1574m叭g,而在锰含量高达114010m叭g的尾矿废弃地上依然生长良好,叶片锰含量最高达1930om叭g。温室培养条件下,随着锰供应水平的增加,两个种群商陆的叶、茎和根的锰含量均呈增加态势,当锰浓度增加到8000林 mol/l时,叶片锰含量达分别为33770m叭g(矿区)和3427om叭g(非矿区),但是商陆地上部Mn积累量先是增加,当锰供应水平为5000卜mol/l时达到最大值,为258.2mg(矿区),251.4mg(非矿区),此后又呈下降态势。根系Mn积累的变化趋势与商陆地上部分Mn积累变化趋势相似。不同锰供应水平下,商陆吸收的Mn90%左右分布在地上部分。在相同的锰供应水平,两个种群商陆表现出相以的锰耐性和积累能力。 超积累植物商陆对锰的吸收和转运与锰供应水平和生长时间密切相关。在Hoagland营养液中加入MnclZ模拟Mn2+污染环境,商陆根、茎和叶的锰含量基本随着锰供应水平的升高而增加;在不同锰供应水平条件下,商陆根、茎和叶锰含量均随着生长时间的延长呈现波动变化,在植物处理5d时出现一个峰值,其后有所降低;商陆在锰处理开始的48h内存在一个快速的吸收过程,但是高锰供应水平变化幅度要大于低锰供应水平。 应用电子显微镜镜和X射线能谱分析技术,研究锰在超积累植物商陆不同组织部位的微分布及不同锰供应水平条件下商陆根和叶的超微结构变化。商陆根系锰含量很低,叶片部位锰含量较高;叶片没有表皮毛;锰在叶片维管束部位含量相当低,其它部位含量较高;小脉锰含量远高于上表皮、下表皮、栅样组织和海绵组织。这表明商陆的超富集能力不可能通过叶片的表皮和表皮毛积累锰来实现,锰主要积累在叶肉组织和小脉部位。生长在2000卿ol/l Mn的营养液条件下,商陆根、叶细胞的细胞结构和细胞器未受到任何伤害,但是有沉积物质出现;当锰供应水平增加到10000脚ol八Mn时,商陆根和叶的细胞己出现部分损伤,细胞壁断裂,细胞核核质不均,叶细胞内叶绿体变形、基粒结构模糊,淀粉粒和嗜饿颗粒增多,但是根细胞和叶细胞中的线粒体、高尔基体和内质网均未受到损伤。这表明商陆对生长环境中的锰胁迫具有极强的耐性。 利用商陆种苗实施低浓度重金属废水的植物修复具有良好的应用前景。选浙江大学博士学位论文薛生国:超积累植物商陆锰富集机理及其对污染水体的修复潜力笼瑟剔取生长一致的商陆幼苗置于不同重金属水平的生长介质,10天后,商陆对Mn、Zn、Cd的去除率分别为35.4%僻9.7%、38.1%一40%、50.8%一53.7%;不同条件下商陆体内重金属含量不同,但均随着生长介质中重金属水平的提高而上升。商陆地上部分Mn含量相对较高,而锌和福则主要吸附在根系。商陆对水体重金属的去除能力表现为植株吸收和根系吸附作用的复合。关键词:商陆(尸妙r口lacca acinosa Roxb.);锰;更多还原

【Abstract】 Manganese, an essential trace element that is found in varying amounts in all tissues, is one of the most widely used metals in industry. However, exposure to excess manganese results in manganese toxicity, including Parkinson-like symptoms, and abnormalities of the reproductive system and the immune system. Manganese -contaminated soils and waters originating from industrial and agricultural activities and mining are becoming an environmental concern following increased awareness of the need for environmental protection.Phytoremediation is attracting interest and attention from governments and enterprises as a potentially cost-effective, engineering-economical and green technique to clean up heavy metal-polluted soil using hyperaccumulators. Unfortunately, some of the strongest hyperaccumulators are relatively small in size and grow very slowly, making it difficult to harvest them mechanically, and limiting the metal extraction that can be achieved. Only a limited selection of the known hyperaccumulators may be suitable for large-scale phytoremediation. Accordingly, exploring the mechanism of manganese tolerance and hyperaccumulation is important to found or create new manganese hyperaccumulator plant which grows rapidly, has substantial biomass, wide distribution and a broad ecological amplitude. The perennial herb Phytolacca acinosa Roxb. (Phytolaccaceae), which occurs in Southern China, has been found to be a new manganese hyperaccumulator by means of field surveys at Xiangtan manganese tailings wastelands, Hunan Province.In the present study, field surveys and glasshouse experiments were conducted to characterize manganese uptake and accumulation of P. acinosa, and to elucidate the possible mechanisms employed by P. acinosa in the tolerance and hyperaccumulation of manganese by means of a series of instrumentations, such asScan electronic microscopy (SEM), Transmission electronic microscopy (TEM), Energy dispersive analysis of X-rays (EDAX), Extended x-ray adsorption fine structure (EXAFS), Inductively-coupled plasma optical emission spectroscopy (ICP-OES), High-speed centrifuger, and so on. In addition, the capacity of P. acinosa to remove heavy metals (Mn, Cd, Zn) from waste water was investigated in the hope of phytoremediation of manganese -contaminated waters. The major results obtained are as follows:P. acinosa not only has remarkable tolerance to Mn, but also has extraordinary uptake and accumulation capacity for this element. The maximum Mn concentration in the leaf dry matter was 19300 mg/kg on Xiangtan Mn tailings wastelands, with a mean of 14480mg/kg. Under nutrient solution culture conditions, the Mn concentration in the leaves reached its highest value (36380 mg/kg) with the bioaccumulation coefficient of 55 at a Mn supply level of 12000 umol/l. P. acinosa could grow normally with Mn supplied at a concentration of 8000 mol/l, although with less biomass than that in control samples supplied with Mn at 5 mol/l. Manganese concentration in the shoots increased with increasing external Mn levels, but the total mass of Mn accumulated in the shoots first increased and then decreased. At a Mn concentration of 5000 umol/l in the culture solution, the Mn accumulation in the shoot dry matter was the highest (258 mg/plant). Partitioning of Mn between the aerial parts and the roots showed that 87% ~ 95% of Mn was transported into the former in all the treatments of the experiment, demonstrating the great capacity of the plant transporting Mn from the roots to the aerial parts. These results confirm that P. acinosa is a Mn hyperaccumulator which grows rapidly, has substantial biomass, wide distribution and a broad ecological amplitude.Both high tolerance and hyperaccumulating ability of Mn in P. acinosa are constitutive properties. Manganese uptake and accumulation by two contrasting populations of P. acinosa were investigated. One population (MP) was from Xiangtan manganese tailings and the other (NMP) was from a Magnolia grandiflora plantation with lower Mn status. In addition to these field investigations, s更多还原