镧处理对干旱胁迫下烟草根系形态与生理特征的影响

以烟草为盆栽试验材料,通过伸根期叶面喷施不同浓度稀土元素镧(Ⅲ),研究了镧处理对旺长期干旱胁迫下烟草根系形态与生理特征变化的影响。结果表明:低浓度La~(3+)(40,80 mg·L~(-1))促进烟草根系发育,显著提高了根系生物量和根活力,高浓度La~(3+)(300 mg·L~(-1))则表现出一定抑制作用。不同浓度La~(3+)均能增强烟草根系SOD、POD活性,维持CAT活性,增加脯氨酸和可溶性蛋白积累,但提高浓度效果不明显,甚至起负向作用。其中以80 mg·L~(-1)处理表现最突出,根系生物量积累和根体积增加显著,根系抗氧化酶活性和渗透调节物质含量提高,提高了烟草抗旱性。     

“常乐”稀土微肥对糯玉米冠层光合特性及产量的影响

在50,100,200,400,600,800 mg.kg-1浓度的"常乐"稀土微肥条件下,研究了其对糯玉米冠层叶的叶绿素含量、荧光参数及产量构成因素的影响。结果表明,糯玉米授粉后棒三叶的叶绿素含量及荧光参数的增大幅度明显随常乐处理剂量的增大而呈规律性变化:即T1至T4处理不仅叶绿素含量呈现明显增大趋势,而当处理浓度为600 mg.L-1时叶绿素含量则表现下降,而且PSII的潜在活性(FV/F0)、光化学最大效率(FV/Fm)和量子效率(ΦPSII)亦表现出相似的规律;但PSII的光化学猝灭系数(qP)则随常乐处理浓度的增大,表现出先增后减的规律,优势明显并具有较高的光合速率,尤其是400 mg.kg-1光合功能强,籽粒产量最高达16320.0 kg.hm-2。另外,授粉后的生育期也对鲜食糯玉米冠层叶绿素荧光参数具有明显正效应,在授粉后16 d时,不同浓度"常乐"稀土微肥处理的鲜食糯玉米不同叶位叶光合速率最大。     

外源H_2O_2对镧胁迫下裸燕麦幼苗光合作用和活性氧代谢的影响

土壤稀土元素污染已成为中国稀土矿区农业可持续发展的制约因素。为探讨信号分子H_2O_2对La胁迫下作物生理响应的调控机制,以裸燕麦品种‘白燕7号’幼苗为试材,采用砂培方法,研究了喷施5 mmol·L~(-1) H_2O_2预处理对1.20 mmol·L~(-1) La~(3+)胁迫下裸燕麦幼苗La含量、生长参数、叶片光合色素含量、气体交换参数和活性氧代谢的影响。结果表明:La胁迫下,裸燕麦幼苗根系和地上部La含量,胞间CO_2浓度(C_i),超氧阴离子(O_2~(·-)), H_2O_2,丙二醛(MDA),类黄酮,总酚和原花青素含量,质膜相对透性(RPP),超氧化物歧化酶(SOD),过氧化物酶(POD),抗坏血酸过氧化物酶(APX)活性显著提高,而根长、株高及根系和地上部干重、叶片光合色素含量、净光合速率(P_n)、气孔导度(G_s)、蒸腾速率(T_r)、抗坏血酸(ASA)、谷胱甘肽(GSH)、可溶性蛋白质、可溶性糖含量明显降低,过氧化氢酶(CAT)活性变化不大。La胁迫下H_2O_2预处理对裸燕麦幼苗根系La含量没有影响,但地上部La含量显著下降;根长、株高及根系和地上部干重、叶片光合色素、 ASA、可溶性蛋白质、可溶性糖、类黄酮、总酚和原花青素含量、 CAT活性、P_n,G_s,T_r提高,C_i, O_2~(·-), H_2O_2, MDA含量、 RPP, SOD, POD和APX活性下降, GSH含量没有改变。表明La胁迫下外源H_2O_2能够抑制La从根系向地上部的转运,并通过调控活性氧清除系统降低膜脂过氧化程度,提高光合速率,缓解植株生长受抑程度,从而增强裸燕麦对La胁迫的适应能力。     

稀土对NaCl胁迫下矮牵牛幼苗生长抑制的缓解效应

以矮牵牛为材料,采用组织培养的方法,探讨硝酸稀土对NaCl胁迫下矮牵牛幼苗生长抑制的缓解效应.结果表明,在试验区间范围内,采用90 mg·L-1硝酸稀土对0.4%的NaCl胁迫下矮牵牛的株高、单株鲜重和根长有明显的缓解效应,分别为:14.5%,19.9%和53.2%,对生根率缓解效应不明显;当NaCl浓度为0.8%,硝酸稀土对株高和单株鲜重缓解效应不明显,对根长和生根率反而有抑制作用,抑制效应分别达到34.6%和48.4%.在一定范围内硝酸稀土对NaCl胁迫矮牵牛根系的POD,SOD和CAT同工酶的活性均有促进作用,表达种类无明显变化.随着硝酸稀土处理浓度的提高,叶片POD同工酶活性呈现低-高-低变化,表达种类无明显变化;SOD同工酶活性增强,表达种类增多;CAT同工酶活性下降,表达种类减少.     

镧对青菜生物量、植株氮磷钾含量及土壤酶活性的影响

利用盆栽试验,研究了镧对青菜生物量、植株氮磷钾含量及土壤酶活性的影响.结果表明,施用镧显著增加了青菜生物量,与对照相比地上部干重提高了5.49%～19.78%,根干重提高了13.51%～51.35%.在低浓度下,随镧浓度的升高,青菜茎叶和根的氮、磷、钾含量逐渐增加,到一定浓度后,随着镧浓度的继续升高,含量反而逐渐降低.镧施入土壤后对脲酶、酸性磷酸酶、转化酶活性表现出刺激作用并随浓度的升高而增强,而对过氧化氢酶活性有轻微的抑制作用,对脱氢酶活性有强烈的抑制作用.     

农用稀土施用量、宽窄行配置对鲜食糯玉米产量构成因素及品质的影响

通过田间小区试验,研究了不同稀土施用量、不同宽窄行配置对鲜食糯玉米产量、产量构成要素和品质的影响。结果表明:农用稀土施用量为200 mg.kg-1时,宽窄行配置为70+50 cm时,吐丝进程最快;皮渣比率、可溶性糖含量、籽粒粗淀粉含量、植株全氮含量均比较小;蒸煮品质即风味、气味,糯性等表现最佳。小花总数、受精小花数、结粒数随着农用稀土施用量增加而减少,且宽窄行配置70+50 cm时,为最大。在农用稀土施用量为600 mg.kg-1时,宽窄行配置60+60 cm时,鲜穗产量为最高,达11883.9 kg.hm-2,在农用稀土施用量为800 mg.kg-1时,宽窄行配置70+50 cm时,鲜穗产量为最低,为9355.8 kg.hm-2。     

添加稀土对镉污染土壤上青椒生长与镉吸收分布的影响

分别以青椒为供试蔬菜、以Cd为供试重金属,采用盆栽试验探索相同规格根际调控基质块中添加不同剂量的碳酸轻稀土对青椒生长、Cd吸收和在器官分配的影响,为今后复合根际修复技术的开展提供理论和实践依据。结果表明:当稀土剂量为40 mg·kg-1时,与不添加稀土的对照相比,极大地促进了青椒苗株高和干重的增加,它们分别提高了21.52%和11.11%。在土壤中含量为5.19 mg·kg-1的Cd胁迫下,保留基质块处理比冲掉块(裸栽)处理的植株地上部干重、生物量、果干重均显著增加,而对根系却没有明显的促进作用。不管基质块中添加不添加稀土,此浓度的Cd胁迫显著抑制了植株根系生长。但适当的稀土添加能够在基质块缓解Cd对青椒毒害的基础上使青椒的生理状况得到进一步改善,而对植株产果没有显著的促进作用。结果还表明:任何剂量的稀土添加对根系Cd含量没有显著降低作用。而当稀土剂量为10 mg·kg-1时,虽然显著促进了茎、叶中Cd的含量,但也显著降低了果实中Cd的含量。由于果实是食用器官,这些结果支撑了稀土添加到基质块作为根际调控方法具有应用价值的重要依据。本试验为以后系统开展复合根际重金属调控研究奠定了基础。     

镨对镉毒害下小麦种子萌发的缓解效应

重金属镉作为毒性较高的环境毒物,不仅危害植物的生长和发育,也对人类健康带来严重威胁。以小麦为试验对象,在200μmol.L-1镉胁迫下,研究了镨对小麦种子萌发及幼苗生理特性的影响,研究结果表明,200μmol.L-1镉胁迫下,小麦种子萌发过程中根生长、根尖细胞有丝分裂指数、α-淀粉酶、APX及CAT的活性明显受到抑制,而MDA含量明显增加。20~80 mg.L-1镨浸种24 h,对200μmo.lL-1镉胁迫下小麦种子的萌发及根、芽的生长具有一定缓解作用,且以40 mg.L-1镨的效果最好,在该浓度下,根长、根鲜重、发芽指数及活力指数明显提高;同时,可提高根尖有丝分裂指数,增强α-淀粉酶活性,提高抗氧化能力,使MDA含量显著降低。然而,100~150 mg.L-1的镨浸种后,种子活力及幼苗生长下降,根尖细胞分裂指数、α-淀粉酶活性降低,MDA含量增加。     

LaCl3对轮藻光合色素含量及抗氧化酶活性的影响

研究了LaCl3对轮藻光合色素含量及抗氧化酶活性的影响,La3+浓度分别为0,0.2,1.0和5.0 μmol·L-1.结果表明0.2和5.0 μmol·L-1La3+处理降低了轮藻叶绿素b的含量,5.0 μmol·L-1 La3+处理降低了叶绿素a+b的含量;类胡萝卜素含量在1.0 μmol·L-1 La3+处理组显著高于对照.随着La处理浓度的提高超氧化物歧化酶的活性逐渐升高,处理组谷胱苷肽过氧化物酶活性均显著高于对照,且在1.0 μmol·L-1La处理组达到最大值,0.2和5.0 μmol·L-1 La3+处理将抑制过氧化氢酶活性,其变化规律与叶绿素b相似.实验浓度的La3+处理可能引起了轮藻植株的氧化损伤,作为应激反应,GSH-Px酶活性及类胡萝卜素含量的升高在一定程度上缓解了氧化损伤.     

稀土元素在土壤-水稻体系中的迁移与吸收累积特征

通过在天然水稻土中施用不同浓度稀土开展为期两年的水稻盆栽实验,在不同生长期系统观测了水稻植株样品的生物量,同时利用ICP-MS测定了土壤及水稻植株各器官中14种稀土元素的含量,并对植株体内稀土含量分布模式及各器官对土壤中稀土的富集与分异进行了对比研究。结果表明,无论苗期还是成熟期,当外施稀土量超过400 mg.kg-1时,水稻植株生物量即开始呈下降趋势,当外施稀土达500mg.kg-1时,生物量降低10%左右,水稻远低于旱作植物小麦对土壤中外施稀土的耐受能力。对照水稻各器官稀土分布模式与对照土壤相似,均呈轻稀土富集,中、重稀土相对亏损型,Eu轻度负异常;但与土壤不同,水稻根部的Tb及地上部各器官的Eu,Tb均出现正异常。土施大量稀土(400~1200 mg.kg-1)对水稻土及稻根的稀土分布模式有显著影响,对茎、叶略有影响,对籽粒影响不明显。植株各器官对土壤稀土的累积能力依次为根>叶>茎>穗轴、谷壳>籽粒。对照水稻根部对土壤中各稀土元素的吸收积累能力大致相同,仅对Tb有更强的选择性吸收。地上部各器官对中、重稀土的累积能力大于轻稀土,并多数对Eu及Tb有更强的累积。水稻的根部及叶、茎对外施稀土有更强的吸收累积能力,随外施稀土浓度增加,其富集系数随之增高,而穗轴和谷壳、籽粒的富集系数变化不大。植株各器官及籽粒对外施稀土中的Nd都表现出更强的吸收累积作用。     

Laser-excited ionic fluorescence spectrometry of rare-earth elements in the inductively-coupled plasma

A pulsed tunable dye laser pumped with an excimer laser is used to excite ionic fluorescence of the rare earth elements in the inductively-coupled plasma. Because several fluorescence lines were observed after laser excitation, it was possible to draw partial energy-level diagrams for most of the rare earths. Non-resonance fluorescence lines were used for all measurements in order to minimize spectral interferences. Detection limits at given excitation wavelengths are reported for each element. Laser-excited ionic fluorescence eliminates the problem of spectral interferences which has been associated with the determination of the rare earths by atomic emission spectrometry in the inductively-coupled plasma.     

Spectrofluorometric determination of trace amounts of terbium with 4-chlorosalicylic acid, EDTA, and cetyltrimethylammonium bromide.

The quadruple complex formed by terbium with 4-chlorosalicylic acid (CSA), EDTA and cetyltrimethylammonium bromide (CTMAB) has been used for the sensitive spectrofluorometric determination of terbium in mixed rare earths. The effect of the experimental conditions on the fluorescence intensity was defined. Under the optimum conditions selected, the fluorescence intensity was linear with the terbium concentration in the range of 3.0 x 10(-8)-1.0 x 10(-5) mol/L with a detection limit of 8.0 x 10(-9) mol/L (S/N = 3). It has been satisfactory for the determination of terbium in mixed rare earths with good recovery.     

稀土复合钴基HMS催化剂的制备及其氯苯催化燃烧性能

以钴基HMS催化剂为主体,从稀土复合方式、不同稀土元素、稀土元素含量等方面系统考察了稀土元素对钴基HMS催化剂氯苯催化燃烧性能的影响。并将孔结构、XRD以及紫外可见漫反射等表征结果与催化活性进行了有效关联。结果发现:Ce较La和Nd能更好地改善钴基HMS的催化性能。同时发现,通过负载法进入HMS孔道的Ce较通过原位法掺杂在骨架的Ce具有更佳的促进作用,且当Ce盐(硝酸铈)的负载量为20%(质量分数)时,效果最好。     

High-light-induced changes on photosynthesis, pigments, sugars, lipids and antioxidant enzymes in freshwater (Nostoc spongiaeforme) and marine (Phormidium corium) cyanobacteria

We studied the effects of high-light exposure (500 micromol m(-2) s(-1) of photosynthetic active radiation) on the cyanobacteria Nostoc spongiaeforme Agardh, a fresh-water alga, and Phormidium corium Agardh (Gomont), a marine alga, with respect to photosynthesis, pigments, sugar content, lipid peroxidation, fatty acids composition, antioxidant enzymes activity and DNA. It was seen that the ratio of variable fluorescence (Fv) to maximum fluorescence (Fm), which is indicative of photosynthetic efficiency, decreased because of the light treatment. The damage to photosynthesis occurred in the antenna system and the photosynthetic II reaction center. Photobleaching of photosynthetic pigments was also observed. High-light treatment also resulted in decreased sugar content, which was probably due to the effect on photosynthesis. Peroxidation of membrane lipids, indicating oxidative damage to lipids and a high level of unsaturation in the cell membrane, was also observed. The activity of antioxidant enzyme superoxide dismutase and ascorbate peroxidase was increased, probably as a result of oxidative damage observed in the form of lipid peroxidation. Quantitative decreases in phospholipid and glycolipid levels were also observed. The level of unsaturated fatty acids in total lipids and glycolipids remained unchanged in both species; however, the level of saturated fatty acids decreased, which slightly changed the ratio in favor of unsaturated fatty acids. Degradation of DNA was also observed in both species. There was a transient plateau 2-4 h after exposure to high-light treatment in the Fv/Fm ratio and in levels of phycobilisome pigments, sugars and antioxidant enzymes after an initial decrease 1 h after the treatment. These findings may indicate a period of partial adaptation to high light that is due to the efficiency of protective processes operational in the two species, which subsequently failed after a longer exposure duration of 4-6 h.     

Preconcentration of rare earth quinolin-8-ol complexes onto activated carbon and determination by first-order derivative x-ray fluorescence spectrometry

A method is described for the determination of traces of rare earths using energy-dispersive x-ray fluorescence spectrometry (EDXRF) after preconcentration of their quinolin-8-ol complexes on activated carbon. Various parameters that influence the adsorptive preconcentration of rare earths on activated carbon, viz., pH, amounts of activated carbon and quinolin-8-ol, time of stirring and aqueous phase volume, were systematically studied. A numerical method based on a simple least-squares procedure using a fifth-order polynomial with 25 consecutive values was developed for smoothing and differentiation of EDXRF data which were previously digitized and averaged. First-order derivative EDXRF in conjunction with adsorptive preconcentration of activated carbon enables down to 10 ng ml^?1 of each rare earth element to be determined.     

多壁碳纳米管对稀土元素的吸附性能

研究了改性多壁碳纳米管(MWCNTs)对稀土元素的吸附。 采用硝酸、次氯酸钠、过氧化氢、高锰酸钾4种方法对MWCNTs进行改性,考察了改性MWCNTs对稀土元素的吸附能力。 采用紫外-可见分光光度法测定稀土元素的浓度,比较了未处理和不同方法处理的MWCNTs对稀土元素的吸附能力。实验结果表明,NaClO改性的MWCNTs对稀土元素的吸附能力最强。以稀土元素钐(Sm)、钆(Gd)、镱(Yb)为代表,研究了NaClO改性MWCNTs对稀土元素的吸附性能。 考察了溶液pH值、离子强度、吸附剂用量、温度等因素对吸附性能的影响。当溶液pH值在2~7范围内,NaClO改性的MWCNTs对Sm、Gd、Yb的吸附随pH值增大而增强。 当离子强度和MWCNTs的用量增大时,对稀土元素的吸附能力降低。3种元素在NaClO改性的MWCNTs上的吸附均为放热过程,其反应焓变ΔH分别为：-6.44、-5.63和8.31 kJ/mol。吸附等温线符合Langmuir和Freundlich等温吸附方程。     

硝酸体系中双功能离子液体萃取剂[A336][CA-12]/[A336][CA-100]萃取稀土的机理研究

研究了双功能离子液体萃取剂[A336][CA-12]/[A336][CA-100]在HNO3体系中对稀土的萃取性能.通过与有机羧酸类萃取剂CA- 12/CA- 100及中性有机膦(磷)类萃取剂TBP和P350的比较得知,在相同条件下,萃取能力按如下顺序降低:[A336] [CA- 12]/[A336] [CA- 100...     

表面活性剂对铽-钛铁试剂荧光反应的增敏作用

研究了阳离子表面活性剂溴化十六烷基三甲铵对铽-钛铁试剂荧光反应的增敏作用,确定了最佳反应条件及络合物的组成比,并与测定铽的七个荧光体系做了比较。测定了稀土合成样中的微量铽。结果令人满意。     

Sensitized Luminescence of Rare Earths

IntroductionAsearlyas1967,inthestudyofthefluorescentcharacteristicsoftheion..associationcomplexEu' -TTA-pyridine,Melentavaetal.[1Jpointedoutthatthef1uorescenceintensityofthesystemwasgreatlyincreasedbytheadditionofGds orTbf' ,andmoreoveronlyinthesuspensiontheenhancementofthefIuo-rescencewasobserved.However,thisphenomenonwasregardedasinterferenceinthepresenceofotherrareearthionsandwaseliminatedbyanextractionpro-cedure.Thisphenomenonwassystemacticallyinvestigatedandcalledcolumines-cence[2j,co…