【作者】 武少伟；

【导师】 朱端卫； 周文兵；

【作者基本信息】 华中农业大学 ， 环境工程， 2010， 硕士

【摘要】 凤眼莲(Eichhornia crassipes)由于其极强的繁殖和生物入侵能力,现已被列为世界十大害草之一。在对凤眼莲的治理和利用两方面,最近几十年来,很多学者都倾向于对凤眼莲利用。凤眼莲对水体具有很强的净化功能,且其对很多重金属都有富集能力,收获后的生物质是一种潜在的优异的吸附剂,但一些金属离子在其体内对于生物质功能的影响并不清楚。为了探讨铁、锰、硅在凤眼莲生物质形成过程中的作用,本文首先研究了铁、锰、硅三种元素在凤眼莲体内的分布,及其对铜、镁、磷、钾等元素分布的影响,并利用FT-IR、XRD、SEM-EDX等手段表征其官能团的丰度、结晶度等生物质材料性质。主要结果如下：(1)前期试验：铁在植物各部位的含量顺序(除Mn、FeSi、FeMnSi处理外)为根>叶>茎；锰在植物各部位的含量顺序为(除Si和Fe处理外)根>茎>叶；Si在植物各部位的含量顺序为(除Mn处理外)根>茎>叶。其中,硅的存在有利于铁在根部的累积,但铁较少转移到茎叶中；缺铁时,Mn使铁更多地向叶分配,以利光合作用。铁可以降低锰的含量,硅增加锰的含量,锰对凤眼莲根部吸收硅有协同作用。浓度过高的铁不利于凤眼莲对高浓度的锰的吸收,对低浓度的锰的吸收有促进作用,却不利于其在根部积累。铁、锰、硅在凤眼莲体内的不同分布将在一定程度地影响凤眼莲生物质材料的功能特性。(2)铁有利于镁在凤眼莲根部积累,而不利于镁向茎、叶部的分配；铁抑制了植物对铜的吸收,但高浓度的铁有利于铜转运到茎和叶中；高浓度铁有利于凤眼莲对磷的吸收,尤其在根部积累；铁能够显著促进凤眼莲对K的吸收,但随着铁浓度的增加,铁会抑制凤眼莲对钾的吸收。锰促进镁在植物根部积累,但抑制镁在茎部和叶部的分布；锰的存在抑制了植物根部对铜的吸收,促进茎叶部铜含量提高；锰促进植物根对磷的吸收,抑制凤眼莲茎和叶对磷的积累,但高浓度的锰抑制植物对磷的吸收；硅有利于凤眼莲根对镁的吸收,却不利于茎和叶对镁的积累；硅抑制凤眼莲根对铜的吸收,有利于铜在叶和茎中分布；硅对凤眼莲吸收磷没有显著影响,但抑制茎和叶对磷的累积；硅抑制凤眼莲对钾的吸收。铁、锰、硅对凤眼莲体内Mg、Cu、P、K这些元素分布的影响在凤眼莲生物质材料形成中的作用有待进一步研究。(3)吸附位点数在凤眼莲体内的规律为：在低浓度铁、锰及其组合处理条件下,凤眼莲秸秆三个部位的酸性位点数顺序为根>茎>叶,施硅条件下,凤眼莲秸秆三个部位的酸性位点数顺序与上述顺序相反,为叶>茎>根。铁降低凤眼莲秸秆的酸性位点数,Mn和Si则能提高其酸性位点数,Mn的作用尤其明显。铁降低凤眼莲叶中的碱性位点数,提升根、茎中的碱性位点数。锰促进植物根产生更多的碱性位点,但在茎和叶部抑制其产生碱性位点。硅抑制凤眼莲根和叶部碱性位点的产生,但促进茎部产生更多的碱性位点。与低浓度相反,高浓度的锰促进植物产生更多的碱性位点,高浓度铁促进植物茎和叶产生更多的碱性位点。由此可见,水环境中不同浓度的铁、锰、硅可以一定程度地改变凤眼莲生物质的荷电特性,从而改变凤眼莲生物质材料的性质。(4)红外图谱表明：Mn和Si增加木质素、果胶以及低分子的木聚糖(半纤维素)等非晶型物质含量,这些物质含有较高的C=C、-CH2、-C-O、-OH、-COOH等活性基团,有利于生物质材料的化学改性。Fe增加-CH3等官能团,降低吸附位点数,不利于生物质材料的化学改性。(5)X-射线衍射图谱表明：凤眼莲生物质根和叶纤维素结晶度含量较低；硅和铁能提升植物根的结晶度,锰降低植物根的结晶度。铁和锰均能降低植物茎叶的结晶度。高浓度铁可以增加植物的结晶度,尤其是植物根部的结晶度；锰降低植物的结晶度。铁锰硅对凤眼莲生物质材料结晶度的影响与其对凤眼莲生物质活性功能团的贡献相一致。(6)能谱分析表明：C、O、Si、P、Na是细胞壁的组成元素,主要分布在植物细胞壁上,Ca和S分布比较均匀。高浓度的铁和锰使植物的细胞壁和根表均分布有Fe和Mn,同时,提升了对P、Al的吸收。植物不同组织中主要元素的分布差异由营养液中不同的铁、锰、硅营养条件引起,与生物质的结构和吸附特性有一定的关系。更多还原

【Abstract】 Eichhornia crassipes (i.e. water hyacinth) has been listed as one of the world’s top ten harmful weeds, due to its strong reproductive capacity. In recent decades, many scholars have tended to use water hyacinth, in control and utilization of water hyacinth. Water hyacinth has a strong water purification function, accumulation ability for heavy metals, and its post-harvest biomass is also a potentially excellent adsorbent, but the role of metal ions in vivo is not clear. To investigate the role of iron, manganese and silicon in water hyacinth biomass, the paper studies the distribution of iron, manganese and silicon, and their influence on Cu, Mg, P, and K in water hyacinth. And FT-IR, XRD, SEM-EDX were used to characterize its functional group abundance, crystallinity, and the element distribution in the plant materials. The main results are as follows:(1) Except for Mn, FeSi, FeMnSi treatments, the sequence of Fe content in the three parts of plant is root> leaf> stem; the sequence of manganese content in the different parts of plant (except for Si and Fe treatments) is root> stem> leaf; the order of silicon content in the three parts of plant (except for Mn treatment) is root> stem> leaf. Silicon in plant benefited iron to accumulate in the roots, but less iron transfer to the stems and leaves. Manganese increased iron allocation to leaves, in order to facilitate photosynthesis when iron deficiency. Iron can reduce the content of manganese in plant, silicon increases the content of manganese and manganese help absorption of silicon in the water hyacinth root. High concentration of iron inhibits the absorption of high concentration manganese in water hyacinth and promotes the water hyacinth’s absorption of low concentration manganese, but inhibits manganese accumulation in roots. The different distribution of iron, manganese, silicon in the water hyacinth will be affected to some extent of water hyacinth biomass material features.(2) Low concentration iron favors magnesium accumulation in water hyacinth roots, inhibits the absorption of Cu in plant. High concentration iron avail the absorption of Cu in stems and leaves. Low concentration iron inhibits the absorption of P in water hyacinth, but high concentration iron enhances the absorption of P, especially in roots. Iron can significantly promote the absorption of water hyacinth on K, but with the increase of the concentration of iron, iron inhibits the absorption of water hyacinth on K. Manganese promotes the magnesium accumulation in plant root, inhibit the accumulation of magnesium in stems and leaves. Mn inhibits the absorption of Cu in plant roots. Low concentration manganese inhibits the accumulation of P in water hyacinth stems and leaves, favors plant root uptake of phosphorus, but high conconcentration manganese inhibits plant uptake of phosphorus. Silicon favors the absorption of magnesium in water hyacinth root and inhibits the accumulation of magnesium in stems and leaves. Silicon favors the absorption of magnesium in water hyacinth root and inhibits the accumulation of magnesium in stems and leaves. To the contrary, silicon inhibits the absorption of Cu in water hyacinth root and favors the accumulation of Cu in stems and leaves. Silicon is no significant effect on P absorption in water hyacinth roots, but inhibits the accumulation in stems and leaves. Silicon inhibits the uptake of K. The effect of iron, manganese and silicon in the water hyacinth affect Mg, Cu, P, K distribution for water hyacinth biomass material the formation needs further study.(3) The rules of adsorption sites in water hyacinth are:the sequence of acidic sites amount among the three parts of plant is root> stem> leaf, in the treatment of Fe, Mn and their combination, and leaf> stem> root in Si treatment. Mn and Si can enhance acidic sites of the plant, in which Mn plays a great role, but Fe reduces the acidic sites. Fe reduces the alkaline sites in leaves and enhances the alkaline sites in root and stem of water hyacinth. Mn promotes the alkaline sites in roots and reduces alkaline sites in stems and leaves. Si reduces the alkaline sites in water hyacinth roots and leaves and promotes stems to produce more alkaline sites. High concentration Mn for water hyacinth produces more alkaline sites and high concentration iron for plant produces more alkaline sites in stems and leaves. This shows that different concentrations of iron, manganese, silicon in water environment can change some extent of characteristics of charge, thus changing the nature of the water hyacinth biomass.(4) FT-IR spectra show that:Mn and Si treated stalks of water hyacinth have more amorphous material, such as lignin, pectin and xylan (hemicellulose), which have more C=C,-CH2,-C-O,-OH,-COOH and acidic sites. Fe increases-CH3 functional group, which can reduce adsorption sites, is not conducive to the chemical modification of biomass materials..(5) X-ray diffraction pattern shows that:the cellulose of roots and leaves of water hyacinth has low crystallinity; silicon and iron can enhance the crystallinity in roots, manganese reduces cellulose crystallinity of the roots. Iron and manganese can reduce the cellulose crystallinity of plant stems and leaves. High concentration iron can increase the cellulose crystallity of plants, especially of plant roots. Manganese reduces cellulose crystallinity of the plant. Fe, Mn and Si has the same contribution on the crystallization of water hyacinth biomass and their functional groups.(6) SEM-EDX analysis shows that:C, O, Si, P and Na is the composition of cell wall elements, and mainly in the plant cell wall, Ca and S is more evenly distributed. High concentration of iron and manganese makes the plant cell wall and the root surface distribution Fe and Mn, also enhance the level of P, Al absorption. Different elements distribution in plant tissues is caused by nutritional conditions of Fe, Mn, Si, and has ralation with biomass structure and adsorption characteristics.更多还原