碱蓬和滨藜对镉吸收分配及其模型拟合研究

发布时间：2018-04-01 18:28

本文选题：盐生植物　切入点：镉　出处：《南京农业大学》2015年硕士论文

【摘要】：镉(Cd)是一种毒性很强的重金属,随着河口和海岸等盐沼湿地生态系统重金属污染的日益加剧,关于盐生植物对Cd吸收、积累及转运方面的研究受到了越来越多的关注。碱蓬(Suaeda salsa)和滨藜(Atriplex triangularis)在我国北部沿海滩涂有着广泛的分布,但目前并不了解这两种盐生植物的Cd耐性如何,对其Cd吸收和分布规律也缺乏深入的认识。此外,碱蓬和滨藜是否直接吸收CdCln2-n络合物尚不清楚,Cl-影响盐生植物Cd吸收的可能作用机制仍需进一步探讨。本文通过水培试验设计,并结合相关重金属吸收和毒性效应模型,对上述问题进行研究,以期为今后盐沼湿地重金属污染修复和海水蔬菜品质安全研究提供理论依据。主要研究内容和结果如下:1.碱蓬和滨藜镉耐性、亚细胞分布及其模型拟合比较了不同类型盐生植物碱蓬和滨藜的Cd耐性,研究了两者对Cd和Na的富集规律及亚细胞水平上的Cd分配差异。结果表明,Cd胁迫下碱蓬和滨藜的根长、株高及干重等均受到不同程度的抑制,两者的表观毒害症状及对Cd的响应敏感度也存在明显差异;根系耐性指数可以作为评价两者Cd耐性的指标,碱蓬表现出更强的Cd耐性。另外,除1μmol·L-1 Cd胁迫下,碱蓬根表的单位面积Cd吸附量均显著高于滨藜;两者吸收的Na大量转运至地上部,吸收的Cd则主要富集在根部,但碱蓬对Cd的转运能力比滨藜弱。亚细胞分布分析发现,两种盐生植物各器官中Cd均主要分布于细胞壁,其次为胞液;细胞壁的固定为两者亚细胞水平上的主要Cd解毒机制,且碱蓬不同器官细胞壁的固定能力比滨藜强,根部Cd亚细胞分布特性对Cd从根部向地上部转运有显著影响。Cd胁迫除产生直接毒害外,也影响着碱蓬和滨藜地上部及根部的Na含量,干扰了两者不同器官及亚细胞水平上的正常Na稳态。通过对碱蓬和滨藜根、茎、叶中Cd亚细胞分布的模型拟合发现,碱蓬根部细胞壁组分的临界Cd浓度和最大积累值分别为133.90μmol·L-1和1680.13 mg-kg-1,表现出较强的耐性;而滨藜茎、叶部细胞器组分的最大积累值较高,分别为13.39mg·kg-1和21.13mg·kg-1,易对细胞器造成严重的毒害。2.固定Cd~(2+)活度下碱蓬和滨藜对镉吸收、分配及其模型拟合设置不同NaCl、Na_2SO_4及Cd处理浓度,使不同处理溶液中Cd~(2+)自由离子活度保持一致,分析了盐生植物对Cd~(2+)自由离子及其它Cd形态(CdCl+、CdCl20、CdSO40)的吸收差异,探讨Cl-影响碱蓬和滨藜Cd吸收的可能作用机制,验证碱蓬和滨藜存在对CdCln2-n络合物直接吸收的假设。研究结果表明,添加NaCl及Na_2SO_4处理维持溶液中Na含量一致,并未对营养液中的离子强度造成显著改变,不同处理也未对碱蓬和滨藜的根部形态及生理指标造成显著的差异。碱蓬的地上部Cd含量及Cd积累量在较低Cl-浓度处理下较高,随着处理营养液中Cl-浓度的增大整体呈下降趋势,根部Cd含量变化趋势与地上部相反,Cd转移系数也随着处理营养液中Cl-浓度的增大而降低,表现出Cl-处理促进碱蓬根部Cd的吸收,但限制了碱蓬根部Cd向地上部转运。仅用Cd~(2+)自由离子活度并不能很好地拟合碱蓬和滨藜根部Cd吸收,碱蓬和滨藜根部Cd含量还受到络合态Cd活度的显著影响。除Cd~(2+)外,碱蓬和滨藜根部还存在对CdCln2-n的直接吸收,但需要注意的是模型拟合参数中CdCl+的反应常数比Cd~(2+)低很多,提高溶液中CdCl+活度增加了碱蓬和滨藜根部对Cd的吸收。
[Abstract]:Cadmium (Cd) is a kind of highly toxic heavy metal, with heavy metal pollution of estuary wetland ecosystem and coastal salt marsh growing on halophytes of Cd absorption, accumulation and transfer of research has attracted more and more attention. Suaedasalsa (Suaeda SALSA) and Saltbush (Atriplex triangularis) has a wide range the distribution in the northern part of China coastal beach, but do not understand how the Cd tolerance of two halophytes, but also the lack of in-depth understanding of the Cd absorption and distribution. In addition, salsa and Saltbush is directly absorbed CdCln2-n complex is not clear, the Cl- effect of halophyte Cd absorption mechanism is still need to be further discussed. Through hydroponic experiment design, combined with the heavy metal absorption and toxic effect of the model, the research on these issues, with a view to the future of heavy metal pollution in salt marsh wetland restoration and water quality of vegetables Provide a theoretical basis for safety research. The main research contents and results are as follows: 1. Atriplex and salsa Cd tolerance, subcellular distribution and model fitting compared Cd tolerance of different types of halophyte and Saltbush, study the differences in Cd distribution both on Cd and Na accumulation and subcellular level. The results showed that Cd under the stress of Suaeda salsa and Atriplex root length, plant height and dry weight were inhibited, both the table and view the toxic symptom of Cd sensitive differences; root tolerance index can be used to evaluate both the Cd tolerance index, Suaeda Cd showed stronger endurance. In addition, in addition to 1 mol L-1 under Cd stress, the adsorption capacity of Cd unit base table area of roots were significantly higher than that of the two Atriplex; the absorption of Na transferred to shoot, the absorption of Cd is mainly enriched in roots, but the transport capacity of Suaeda Cd better than Atriplex sub weak. Cell distribution analysis showed that two kinds of halophytic plant organs in Cd were mainly distributed in the cell wall, followed by the cytosol; cell wall fixed to the main Cd detoxification mechanism between subcellular level, and different organs of Suaeda cell wall immobilization ability than Atriplex, root Cd subcellular distribution characteristics of Cd from roots. Translocation significantly affected the.Cd stress in direct toxicity, also affect Na content of Suaeda salsa and Atriplex shoots and roots, interfere with the normal Na steady state two different organs and subcellular level. Based on the salsa and Hama Ne, stems, the subcellular distribution of Cd in the model fitting leaf, critical Cd the concentration and the maximum accumulation of Suaeda root cell wall components were 133.90 mol L-1 and 1680.13 mg-kg-1 showed stronger tolerance; while Atriplex stem leaf, the maximum accumulation of organelles were higher, 13.39mg and kg- respectively. 1 and 21.13mg - kg-1, easy to cause the serious toxicity of.2. Cd~ fixed on the organelles (2+) activity of Suaeda salsa and Atriplex on Cd uptake, distribution and model fitting set different NaCl, Na_2SO_4 and Cd concentrations, the different treatment solution Cd~ (2+) free ion activity consistent analysis of halophytes the Cd~ (2+) free ions and other forms of Cd (CdCl+, CdCl20, CdSO40) absorption difference, investigate the possible mechanism of Cl- effects of Suaeda salsa and Atriplex Cd absorption, verification of Suaeda salsa and Atriplex CdCln2-n complex of direct absorption hypothesis. The results show that the addition of NaCl and Na_2SO_4 maintain the Na content in solution consistent, did not cause significant change of ionic strength in nutrient solution, different treatments nor on Suaeda salsa and Atriplex root morphological and physiological indexes have significant difference. The content of Cd and Cd. Accumulation in the low concentration of Cl- The higher the overall downward trend, with the increase of Cl- concentration in nutrient solution, the root Cd content change of the upper trend and to the contrary, Cd transfer coefficient decrease with the increasing of Cl- concentration in nutrient solution and showed Cl- treatment promoted the absorption of Cd in roots of Suaeda salsa roots, but limits the Cd translocation to the shoot. Only Cd~ (2+) free ion activity is not a good fit of Suaeda salsa and Atriplex root Cd uptake, Suaeda salsa and Atriplex Cd content in roots are also affected by the complex state of the activity of Cd Cd~ (2+). In addition, salsa and Saltbush roots have direct absorption of CdCln2-n, but need to pay attention to CdCl+ is the model parameters in reaction constant than Cd~ (2+) is much lower, increase the activity of CdCl+ in solution increased the absorption of Cd by Suaeda salsa and Atriplex root.

【学位授予单位】：南京农业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X173

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