水溶性有机质对土壤中镉吸附行为的影响

水溶性有机质 (DOM)是陆地生态系统和水生生态系统中的一种很活跃的组分 .本文以赤红壤、水稻土和褐土作为供试土壤 ,研究了来源于稻秆和底泥的DOM对土壤中Cd吸附行为的影响 .DOM对土壤中Cd的吸附行为具有明显的抑制作用 .这种抑制作用与土壤类型和DOM种类有关 .在 3种供试土壤中 ,无论添加稻秆DOM还是底泥DOM ,都会使Cd的最大吸附容量和吸附率明显降低 ,其下降幅度为17 3%～ 93 9%.在添加同一种DOM的前提下 ,DOM对Cd吸附的抑制作用均为 :赤红壤 >水稻土 >褐土 .如果不添加DOM ,则土壤对Cd的最大吸附容量主要取决于土壤固相的吸附特性 ,添加DOM后土壤对Cd的最大吸附容量则主要取决于液相中的DOM .由此推断 ,传统的看法 ,通过施用有机肥来固定土壤中的Cd并达到治理重金属污染土壤的观点值得商榷 .     

Comparison of Cadmium Effect on Willow and Poplar in Response to Different Cultivation Conditions

Salix alba L. and Populus×euroamericana cv. Robusta cuttings were grown in 10 μM Cd(NO₃)₂ (direct treatment) or in Knop solution and afterwards in Cd(NO₃)₂ (indirect treatment). Cd impact on rooting of directly treated plants and its impact on normally formed roots and shoots of indirectly treated plants were studied. The cumulative length, number and biomass of willow roots, pigment and starch contents, leaf net photosynthetic rate and dry mass/leaf area ratio of willow leaves were positively influenced by indirect treatment. However, indirectly treated poplars were more sensitive to Cd than directly treated ones. Indirect treatment lowered root Cd uptake in willow, Cd accumulation in cuttings of both species and Cd accumulation in poplar shoots. Cd-caused structural changes were similar in both species and in both treatments. Root apices, rhizodermis and cortex were the most seriously damaged root parts. In directly treated willow, the structure of central cylinder (0.5 – 1 cm from apex) remained unchanged in contrast to indirectly treated plants. Formation of cambium close to the apex indicated shortening of root elongation zone of indirectly treated plants. Directly Cd-treated poplar roots exhibited unusual defence activity of root apical meristem and accumulation of darkly stained material around central cylinder. This revised version was published online in July 2006 with corrections to the Cover Date.     

Hg2+、Cd2+和Cu2+对菹草光合系统及保护酶系统的毒害作用

研究了Hg2 、Cd2 、Cu2 对高等水生沉水植物菹草光合系统及保护酶系统的毒害作用。结果表明 :3种离子均使菹草叶片叶绿体自发荧光强度、叶绿素含量、光合速率降低。Hg2 、Cd2 、Cu2 对菹草保护酶系统存在不同的影响 ,短时间低浓度条件下 ,诱导超氧化物歧化酶 (SOD )、过氧化氢酶 (CAT)、过氧化物酶(POD)活性上升 ,随着污染时间的延长、污染浓度的增加 ,酶活性下降 ,其中SOD活性上升持续时间最长 ,下降最慢。 3种离子均使菹草可溶性蛋白含量减少。Hg2 、Cu2 毒性较强 ,Cd2 毒性较弱。Hg2 、Cu2 对菹草的致死浓度为 0 .5～ 1mg/L ,Cd2 为 1～ 2 .5mg/L     

重金属镉、锌在菹草叶细胞中的超微定位观察

水环境污染中十分突出的是重金属的污染 ,主要来源为流入物、渗漏和大气沉降 (Ｌａｒｃｈｅｒ ,1995 )。由于重金属污染物不但不能被微生物所分解 ,而且能在生物体内富集 ,并通过水生食物链的生物放大作用而对高营养级的生物甚至人类造成危害 ,因此日益引起人们的特别关注。许多研究从超微结构损伤和生理生化的角度研究了重金属对植物的毒害机制。施国新等 (2 0 0 0 )观察了重金属汞、镉污染对水生植物黑藻叶细胞的超微结构损伤。彭鸣等 (1991)研究了重金属镉、铅诱导的玉米超微结构的变化。李荣春 (2 0 0 0 )研究了Ｃｄ、Ｐｂ及其复合污染…     

植物对镉胁迫响应的研究进展

总结了近年来植物对一重要环境污染物镉的反应研究报道。探讨了镉对植物的各种毒性效应,并论述植物对镉胁迫采取的相应防御机制,如络合（PC、MT）、应激（应激乙烯、应激蛋白）,及额外防御机制,如细胞壁固定化、原生质膜排除,区域化、过氧化物酶等。     

植被恢复对退化红壤表层土壤颗粒中有机碳和Pb、Cd分布的影响

采用原状土壤水稳性团聚体分离方法提取不同粒径的土壤颗粒,测定其有机碳及重金属元素Pb、Cd的含量,研究了退化红壤在植被恢复下表层(0～10cm和10～20cm)土壤颗粒中有机碳与重金属分布及其关系.这些土壤颗粒中有机碳和重金属元素Pb、Cd的含量范围分别介于7.5～15g/kg,11～20mg/kg和20～70μg/kg,且粒组间有显著差异.尽管所测组分的含量以＜0.002mm粒组中最高,但2～0.25mm的粒组占其总量的50%左右,其次约20%存在于0.25～0.02mm粒组中.以土壤粒组中分量而言,有机碳和所测的重金属元素间有密切的依存关系.与荒地相比,植被恢复措施降低了各土层2～0.25mm粒组中Pb的含量和分量,但提高了0～10cm土层Cd的含量和分量.在所研究的几种处理中,玉米-包菜处理显著地促进了有机碳和重金属在各颗粒粒组中的均衡分布.因此,退化红壤植被恢复措施改变了上壤颗粒中有机碳和重金属的分布,因而可能影响着土壤环境中有机碳和重金属的形态及其活性.对于这些措施下土壤环境中有机碳和重金属的生物有效性机制尚需进一步研究.     

Zn、Cd及其复合对小麦幼苗吸收Ca、Fe、Mn的影响

研究了溶液培养条件下Cd、Zn及其复合对小麦幼苗吸收Ca、Fe、Mn的影响.结果表明,小麦幼苗对Zn、Cd的吸收随溶液中Cd²⁺、Zn²⁺浓度的升高而增加,Cd、Zn同时存在时与其单独作用时幼苗对它们的吸收不同,Zn影响幼苗对Cd的吸收,Cd对Zn的吸收起抑制作用.Ca、Mn的吸收随溶液中Cd²⁺、Zn²⁺浓度升高而呈下降趋势,在Cd单独处理组和Zn单独处理组中Fe的吸收随Cd²⁺、Zn²⁺浓度升高而增加,但在Zn+Cd处理组中,Fe的吸收则呈下降趋势,其效应方式还与作物具体部位有关.     

磷缓解水鳖镉毒害的生理研究

研究了Cd对水鳖生理生化过程的影响及Pi对Cd胁迫的缓解作用。结果显示,Cd能抑制水鳖的代谢和生长,使叶绿素含量与光合速率下降,呼吸速率与可溶性糖含量增加,POD活性增强;当加入0.6mmol/L Pi后,能相对减轻Cd造成的毒害,表现出Pi对Cd的拮抗和缓解作用。     

Enhancement of cadmium accumulation in sweet sorghum as affected by nitrate

• The Cadmium (Cd)‐polluted soils are is an increasing concern worldwide. Phytoextraction of Cd pollutants by high biomass plants, such as sweet sorghum, is considered an environmentally‐friendly, cost‐effective and sustainable strategy for remediating this problem. Nitrogen (N) is a macronutrient essential for plant growth, development and stress resistance. Nevertheless, how nitrate, as an important form of N, affects Cd uptake, translocation and accumulation in sweet sorghum is still unclear.
• In the present study, a series of nitrate levels (N1, 0.5 mm ; N2, 2 mm ; N3, 4 mm ; N4, 8 mm and N5, 16 mm ) with or without added 5 μm CdCl₂ treatment in sweet sorghum was investigated hydroponically.
• The results indicate that Cd accumulation in the aboveground parts of sweet sorghum was enhanced by optimum nitrate supply, resulting from both increased dry weight and Cd concentration. Although root‐to‐shoot Cd translocation was not enhanced by increased nitrate, some Cd was transferred from cell walls to vacuoles in leaves. Intriguingly, expression levels of Cd uptake and transport genes, SbNramp1, SbNramp5 and SbHMA3, were not closely related to increased Cd as affected by nitrate supply. The expression of SbNRT1.1B in relation to nitrate transport showed an inverted ‘U’ shape with increasing nitrate levels under Cd stress, which was in agreement with trends in Cd concentration changes in aboveground tissues.
• Based on the aforementioned results, nitrate might regulate Cd uptake and accumulation through expression of SbNRT1.1B rather than SbNramp1, SbNramp5 or SbHMA3, the well‐documented genes related to Cd uptake and transport in sweet sorghum.

     

不同炭化温度制备的蚕丝被废弃物生物炭对重金属Cd2+的吸附性能

以蚕丝被废弃物为原料,在300、500和700 ℃高温缺氧条件下热解炭化制备成3种生物炭(BC300、BC500和BC700).利用扫描电镜(SEM)、傅里叶红外光谱仪(FT-IR)、X-射线衍射仪(XRD)、比表面积分析仪等对其理化性质进行表征,并研究了不同温度下制备的生物炭对溶液中Cd²⁺的吸附特性.结果表明: 随着炭化温度上升,BET比表面积、pH、灰分均增大,生物炭表面形态结构越来越不规则.XRD结果显示:不同温度下获得的生物炭中均含有一定量的方解石,FT-IR光谱图上的峰主要为-OH和方解石典型的吸收峰;pH对生物炭吸附Cd²⁺的影响不大;Langmuir方程能更好地拟合3种生物炭对Cd²⁺的吸附等温过程,其最大吸附量分别为25.61、52.41和91.07 mg·g^-1.3种生物炭对Cd²⁺吸附过程均更符合准二级动力学方程,且BC700对Cd²⁺的吸附效果最佳.进一步研究离子浓度及阳离子共存对BC700吸附Cd²⁺的影响,结果显示: NaCl浓度越高,对Cd²⁺的吸附抑制越明显;共存阳离子中,Ca²⁺和Mg²⁺对Cd²⁺的吸附抑制更明显,而K⁺几乎无影响.因此,以蚕丝被废弃物制备的生物炭作为去除水体中Cd²⁺的吸附剂具有较强的应用潜力.