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铁皇冠(Microsorium pteropus)对水体砷污染的生理响应及修复
陈福龙
学位类型博士
导师潘响亮
2015
学位授予单位中国科学院大学
学位授予地点北京
学位专业生态学
关键词铁皇冠 砷污染 生理响应 植物修复
摘要砷是被广泛关注的五毒元素之一,具有致癌、致畸、致突变效应,对生物体危害极大。水体砷污染已成为当今全球性的环境问题,中国是砷污染较严重的国家之一,新疆是我国大陆最早发现地方性砷中毒的省区,新疆矿产资源的开采和干旱区盐碱的环境,进一步加重了水体砷的污染,因此,为寻求一种实用性强并且高效的水体砷污染治理的生物修复技术,本研究以一种新型的水生蕨类-铁皇冠为材料,通过透射电镜、扫描电镜和激光共聚焦扫描显微技术研究了砷对铁皇冠细胞和亚细胞结构的影响;通过快速叶绿素荧光技术研究了砷对铁皇冠光合系统的影响;通过分光光度法研究了砷对铁皇冠抗氧化系统、渗透调节物质和膜脂过氧化的影响;通过色谱技术、分子荧光和红外光谱技术研究了砷对铁皇冠根系分泌物的影响;同时开展了铁皇冠对水体砷污染修复效率的研究。本研究取得的主要结论如下: (1)高浓度的三价砷As(Ⅲ)对铁皇冠的膜系统、叶绿体、线粒体和气孔均有破坏作用。砷在铁皇冠的细胞结构中,主要分布在细胞壁上,尤其是根的细胞壁。SEM-EDX研究结果表明,溶液中同时存在Fe2+和As(Ⅲ)时,铁皇冠根尖表面Fe和As含量均增加,可能促使根尖表面形成了Fe膜。 (2)叶绿素荧光诱导动力学曲线和荧光参数的变化结果表明,高浓度(25 mg L-1和50 mg L-1)As(Ⅲ)对铁皇冠的光系统有显著的抑制作用,低浓度(1 mg L-1)和中浓度(5 mg L-1)As(Ⅲ)对光系统的影响相对较小。PSⅠ和PSⅡ同时测定的结果表明,高浓度(25 mg L-1和50 mg L-1)As(Ⅲ)对铁皇冠PSⅡ有抑制作用强于PSⅠ。叶绿体色素含量的测定结果表明,高浓度(25 mg L-1和50 mg L-1)As(Ⅲ)明显的抑制叶绿体色素的合成,中等浓度(5 mg L-1)As(Ⅲ)对铁皇冠叶绿素a和类胡萝卜素的合成有一定的促进作用,对叶绿素b合成有一定的抑制作用,低浓度(1 mg L-1)As(Ⅲ)对叶绿体色素的合成影响不大。 (3)1 mg L-1和5 mg L-1As(Ⅲ)显著促进了铁皇冠蛋白质的合成,25 mg L-1和50 mg L-1As(Ⅲ)促进根中蛋白质的合成,抑制叶中蛋白质的合成。抗氧化酶系统中,铁皇冠根中超氧化物歧化酶SOD的活性变化显著,对清除自由基起主要作用,低中浓度的As(Ⅲ)(1 mg L-1和5 mg L-1)使根中SOD的活性显著增加,高浓度As(Ⅲ)(25 mg L-1和50 mg L-1)使根SOD活性显著的降低,在茎中SOD的活性总体上呈现增加的趋势,而在叶中的变化趋势与根中变化趋势相反,呈先降低后增加的趋势。在根中过氧化氢酶CAT活性呈先增加后降低的趋势,在茎中CAT活性呈降低的趋势,叶中的CAT活性与根中的CAT活性呈负相关关系。过氧化物酶POD在铁皇冠中表达量很低或不表达。As(Ⅲ)胁迫下,丙二醛MDA和游离脯氨酸变化显著,尤其在根中,可作为砷污染检测的指标。 (4)As(Ⅲ)胁迫下,改变了铁皇冠根系荧光物质的分泌能力,主要是影响了铁皇冠根系蛋白质的分泌,As(Ⅲ)既促进了铁皇冠根系某种蛋白质的分泌,又抑制了另外几种蛋白质的分泌;铁皇冠分泌的某种蛋白质或多肽与As(Ⅲ)有着很强的络合能力;As (Ⅲ)抑制了铁皇冠根系分泌乳酸。 (5)不同实验条件下,铁皇冠对砷吸收研究结果表明:铁皇冠各器官中砷含量均随着As(Ⅲ)浓度的增加而增加,但砷各形态在各器官中增加的程度不同。在25 mg L-1 As(Ⅲ)浓度下,根、根状茎和叶中砷的含量已超过了陆生砷超富集植物的临界标准1000 mg kg-1干重,具备了修复水体砷污染的潜力。铁皇冠在根中主要存在的是有机砷,在根状茎中主要存在的是三价砷,在叶中主要是三价砷和有机砷。铁皇冠在100 μmol photons m-2s-1光通量下砷积累量最高,低于或高于这个光通量,砷积累量均降低。铁皇冠砷吸收与氯化钠之间有一定的拮抗作用,但不同浓度的氯化钠抑制的器官不同,低盐(1.5%NaCl)条件下,抑制了根和根状茎对砷(无机砷)的吸收,高盐(2.5%NaCl)条件下,抑制了根状茎和叶对无机砷的吸收。对照组自来水中的磷浓度促进铁皇冠根尖表面形成铁膜,0.5 mg L-1磷促进铁皇冠中有机砷向无机砷的转化,并且促进了根状茎和叶对无机砷的吸收,而2.5 mg L-1磷则抑制铁皇冠根和根状茎对砷的吸收,但对叶吸收砷的影响较小。偏酸性条件(pH=5.5)下,促进了铁皇冠对有机砷和五价砷的积累和转化,而三价砷含量变化不大。在碱性条件(pH=8.5)下,对铁皇冠吸收砷有一定的抑制作用。 (6)铁皇冠对含砷尾矿中砷的去除率较高,1g铁皇冠处理尾矿淋滤液5 d,即可去除水体中24.95 μg As,同时铁皇冠对Mn的去除率非常高,修复后Mn的浓度降低了88.15%。在相对比较短的时间内,一定质量的铁皇冠对一定浓度的砷是有一定的吸收容量的,并且达到这个吸收容量后,有可能也存在着吸砷和排砷的平衡机制。
其他摘要Arsenic (As) is one of the most toxic elements, and poses great risk to organisms due to its carcinogenic, teratogenic and mutagenic effects. Currently, water arsenic contamination has become a global environment problem. Severe As contamination has been observed in China. Xinjiang is the first place in mainland China where endemic arsenic poisoning event was reported. Furthermore, due to the exploitation of mineral resource in Xinjiang and its special arid saline environment, the water As contamination here is further aggravated. Therefore, it is necessary to develop a practical and efficient method for remediation of As-polluted water. In this work, a new kind of aquatic fern -Microsorium pteropus was selected to study its physiological responses and remediation for As in water. Transmission electron microscopy (TEM), scanning electron microscopy (SEM), and confocal laser scanning microscope (CLSM) were employed to investigate the effects of As on cell structure of M. pteropus at cell and subcell levels. The rapid chlorophyll fluorescence technology was also employed to study the effects of As on the photosynthetic system of M. pteropus. Effects of As on the antioxidant systems, osmotic regulation substances, and membrane lipid peroxidation of M. pteropus were studied by spectrophotometry. Effects of As on the root exudates of M. pteropus were studied complementarily by chromatography, infrared spectroscopy, and molecular fluorescence spectroscopy. Moreover, remediation efficiency of As in water M. pteropus for arsenic contamination was studied. The main conclusions of this study can be drawn as the followings: (1) Membrane system, chloroplast, mitochondria, and stoma of M. pteropus were damaged by high concentration of As (Ⅲ). In M. pteropus cell, As was mainly distributed in cell walls, especially for root cell. SEM-EDX results showed that, in the solution existing simultaneously Fe2+ and As(Ⅲ), Fe and As contents were increased on surface of root tip of M. pteropus, which might lead to form the Fe plaque on surface of root tip. (2) Results of the changes in chlorophyll fluorescence induction kinetics curves and fluorescence parameters showed that photosynthetic system of M. pteropus was significantly inhibited by high concentrations (25 mg L-1 and 50 mg L-1) of As (Ⅲ); while less influence was observed for As (Ⅲ) at low concentration (1 mg L-1) and medium concentration (5 mg L-1). Results of simultaneous determination of Photosystem I (PS I) and PS II showed that high concentrations (25 mg L-1 and 50 mg L-1) of As (Ⅲ) posed higher inhibitory effects on PS II of M. pteropus than PS I. Moreover, according to results of chloroplast pigment contents, it was showed that the synthesis of chloroplast pigment was hampered by high concentrations (25 mg L-1 and 50 mg L-1) of As (Ⅲ), but the synthesis of chlorophyll a and carotenoids was promoted by medium concentration (5 mg L-1) of As (Ⅲ). While, low concentration (1 mg L-1) of As (Ⅲ) presented less effect on the synthesis of chloroplast pigment. (3) The synthesis of proteins in M. pteropus was significantly facilitated by 1mg L-1 and 5 mg L-1 As (Ⅲ), but the synthesis of proteins in root was facilitated, in leaf was inhibited by 25 mg L-1 and 50 mg L-1 As (Ⅲ). For antioxidant enzyme system, the activity of superoxide dismutase (SOD) in the root of M. pteropus was significantly changed, indicating that SOD played a main role in scavenging free radicals. The activity of SOD in M. pteropus root was also significantly enhanced by low concentration (1 mg L-1) and medium concentration (5 mg L-1) of As(Ⅲ), but dramatically decreased by high concentrations of As (25 mg L-1 and 50 mg L-1). Overall, the activity of SOD in M. pteropus rhizome showed an upward tendency with the increasement of As(Ⅲ) concentration. However, its activity in M. pteropus leaf tended to decrease at low concentration of As(Ⅲ) and then increase at higher concentration of As(Ⅲ). For catalase (CAT), its activity in M. pteropus root showed first a upward tendency and was decreased thereafter with the increment of As(Ⅲ) concentration. While its activity in M. pteropus stem was decreased with the increment of As(Ⅲ) concentration. The CAT activity in M. pteropus leaf was negatively correlated to its activity in M. pteropus root. Low or no expression of POD in M. pteropus was observed under the experimental conditions. Contents of MDA and free proline were significantly changed under the stress of As(Ⅲ), especially in the root, suggesting that both of them could be used as bioindicators for As-polluted water. (4) The secretion capacity of fluorescent substances in M. pteropus was altered by the presence of As(Ⅲ). As(Ⅲ) mainly affected the protein secretion in M. pteropus root. As(Ⅲ) can not promote the secretion of one type of protein in M. pteropus root, but inhibit the production of several other proteins. Proteins or peptides secreted by M. pteropus showed a high binding affinity for As(Ⅲ). As(Ⅲ) also impeded the secretion of lactic acid in M. pteropus root. (5) Results of As uptake of by M. pteropus under different experimental conditions showed that arsenic content in different organs of M. pteropus was increase with the increment of As (Ⅲ) concentration, but contents of different species of As in different organs were increased in different degree. The concentration of total As in roots, rhizomes and leaves of M. pteropus cultured in water containing 25 mg L-1 As (Ⅲ) was exceeded the threshold value of 1000 mg kg-1 DW in arsenic hyperaccumulators in terrestrial plants, indicating that M. pteropus possesses with the potential of remediating As-polluted water. Arsenic mainly existing in the root of M. pteropus is in organic forms. Arsenic mainly exists in the forms of trivalent inorganic arsenic in the rhizomes, and mainly in the forms of trivalent arsenic and organic one in the leaves of M. pteropus. Under the condition of 100 μmol photons m-2s-1, arsenic accumulation in M. pteropus are highest; while below or above this luminous flux, the arsenic accumulation is lower. To some degree, an antagonistic action between NaCl and As accumulation in M. pteropus was observed. But the inhibition of NaCl depended on its concentrations in different organs. The accumulations of As (inorganic As) in roots and rhizomes and inorganic As in rhizomes and leaves were inhibited by the presence of low salt (1.5% NaCl) and high salt (2.5% NaCl), respectively. Phosphorus concentration of in tap water of control group facilitated the Fe plaque on surface root tip. 0.5 mg L-1 phosphorus facilitated the transformation of organic arsenic in M. pteropus to inorganic arsenic and the accumulation of inorganic arsenic in rhizomes and leaves of M. pteropus. The accumulation of As in roots and rhizomes of M. pteropus was inhibited by the presence of 2.5 mg L-1 phosphorus. But the influence of 2.5 mg L-1 phosphorus on the accumulation of As in leaves was negotiable. Base on the results of pH, the accumulation and transformation of organic arsenic and pentavalent arsenic in M. pteropus were facilitated under acidic condition (pH=5.5); while the accumulation of As in M. pteropus was inhibited under alkaline conditions (pH=8.5). Moreover, the contents of trivalent As in M. pteropus were slightly changed under acidic condition (pH=5.5). (6) M. pteropus showed high removal efficiency for As in tailings. 24.95 μg of As in the mine tailing leachates was removed by the presence of 1 g of M. pteropus after 5-day treatment. M. pteropus also presented high removal efficiency for Mn. Under the same conditions, the removal efficiency of Mn in the mine tailing leachates was up to 88.15%. In a relatively short period of time, a certain amount of the M. pteropus showed some sorption capacities for a certain concentration of As, indicating the presence of possible mechanisms controlling the equilibrium of As accumulation and excretion in M. pteropus.
学科领域生态学
语种中文
文献类型学位论文
条目标识符http://ir.xjlas.org/handle/365004/14595
专题研究系统_荒漠环境研究室
作者单位中科院新疆生态与地理研究所
推荐引用方式
GB/T 7714
陈福龙. 铁皇冠(Microsorium pteropus)对水体砷污染的生理响应及修复[D]. 北京. 中国科学院大学,2015.
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