本文選題：鹽生植物　切入點：鎘　出處：《南京農(nóng)業(yè)大學》2015年碩士論文

【摘要】：鎘(Cd)是一種毒性很強的重金屬,隨著河口和海岸等鹽沼濕地生態(tài)系統(tǒng)重金屬污染的日益加劇,關(guān)于鹽生植物對Cd吸收、積累及轉(zhuǎn)運方面的研究受到了越來越多的關(guān)注。堿蓬(Suaeda salsa)和濱藜(Atriplex triangularis)在我國北部沿海灘涂有著廣泛的分布,但目前并不了解這兩種鹽生植物的Cd耐性如何,對其Cd吸收和分布規(guī)律也缺乏深入的認識。此外,堿蓬和濱藜是否直接吸收CdCln2-n絡(luò)合物尚不清楚,Cl-影響鹽生植物Cd吸收的可能作用機制仍需進一步探討。本文通過水培試驗設(shè)計,并結(jié)合相關(guān)重金屬吸收和毒性效應(yīng)模型,對上述問題進行研究,以期為今后鹽沼濕地重金屬污染修復和海水蔬菜品質(zhì)安全研究提供理論依據(jù)。主要研究內(nèi)容和結(jié)果如下:1.堿蓬和濱藜鎘耐性、亞細胞分布及其模型擬合比較了不同類型鹽生植物堿蓬和濱藜的Cd耐性,研究了兩者對Cd和Na的富集規(guī)律及亞細胞水平上的Cd分配差異。結(jié)果表明,Cd脅迫下堿蓬和濱藜的根長、株高及干重等均受到不同程度的抑制,兩者的表觀毒害癥狀及對Cd的響應(yīng)敏感度也存在明顯差異;根系耐性指數(shù)可以作為評價兩者Cd耐性的指標,堿蓬表現(xiàn)出更強的Cd耐性。另外,除1μmol·L-1 Cd脅迫下,堿蓬根表的單位面積Cd吸附量均顯著高于濱藜;兩者吸收的Na大量轉(zhuǎn)運至地上部,吸收的Cd則主要富集在根部,但堿蓬對Cd的轉(zhuǎn)運能力比濱藜弱。亞細胞分布分析發(fā)現(xiàn),兩種鹽生植物各器官中Cd均主要分布于細胞壁,其次為胞液;細胞壁的固定為兩者亞細胞水平上的主要Cd解毒機制,且堿蓬不同器官細胞壁的固定能力比濱藜強,根部Cd亞細胞分布特性對Cd從根部向地上部轉(zhuǎn)運有顯著影響。Cd脅迫除產(chǎn)生直接毒害外,也影響著堿蓬和濱藜地上部及根部的Na含量,干擾了兩者不同器官及亞細胞水平上的正常Na穩(wěn)態(tài)。通過對堿蓬和濱藜根、莖、葉中Cd亞細胞分布的模型擬合發(fā)現(xiàn),堿蓬根部細胞壁組分的臨界Cd濃度和最大積累值分別為133.90μmol·L-1和1680.13 mg-kg-1,表現(xiàn)出較強的耐性;而濱藜莖、葉部細胞器組分的最大積累值較高,分別為13.39mg·kg-1和21.13mg·kg-1,易對細胞器造成嚴重的毒害。2.固定Cd~(2+)活度下堿蓬和濱藜對鎘吸收、分配及其模型擬合設(shè)置不同NaCl、Na_2SO_4及Cd處理濃度,使不同處理溶液中Cd~(2+)自由離子活度保持一致,分析了鹽生植物對Cd~(2+)自由離子及其它Cd形態(tài)(CdCl+、CdCl20、CdSO40)的吸收差異,探討Cl-影響堿蓬和濱藜Cd吸收的可能作用機制,驗證堿蓬和濱藜存在對CdCln2-n絡(luò)合物直接吸收的假設(shè)。研究結(jié)果表明,添加NaCl及Na_2SO_4處理維持溶液中Na含量一致,并未對營養(yǎng)液中的離子強度造成顯著改變,不同處理也未對堿蓬和濱藜的根部形態(tài)及生理指標造成顯著的差異。堿蓬的地上部Cd含量及Cd積累量在較低Cl-濃度處理下較高,隨著處理營養(yǎng)液中Cl-濃度的增大整體呈下降趨勢,根部Cd含量變化趨勢與地上部相反,Cd轉(zhuǎn)移系數(shù)也隨著處理營養(yǎng)液中Cl-濃度的增大而降低,表現(xiàn)出Cl-處理促進堿蓬根部Cd的吸收,但限制了堿蓬根部Cd向地上部轉(zhuǎn)運。僅用Cd~(2+)自由離子活度并不能很好地擬合堿蓬和濱藜根部Cd吸收,堿蓬和濱藜根部Cd含量還受到絡(luò)合態(tài)Cd活度的顯著影響。除Cd~(2+)外,堿蓬和濱藜根部還存在對CdCln2-n的直接吸收,但需要注意的是模型擬合參數(shù)中CdCl+的反應(yīng)常數(shù)比Cd~(2+)低很多,提高溶液中CdCl+活度增加了堿蓬和濱藜根部對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.

【學位授予單位】：南京農(nóng)業(yè)大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：X173

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