Physiology and Ultrastructure of Azolla imbricata as Affected by Hg 2+ and Cd 2+ Toxicity

The toxic effects of different gradient concentrations of Hg2+ and Cd2+ on chlorophyll content, chlorophyll a/b value, photosynthetic O-2 evolution, respiration rate, anti-oxidase system (superoxide dismulase (SOD), catalase (CAT), peroxidase (POD)) and ultrastructure of the cells of Azolla imbricata (Roxb.) Nakai were studied. The results showed that with Hg2+ and Cd2+ increase, chlorophyll content and chlorophyll a/b value, photosynthetic O-2 evolution decreased drastically; respiration rate peaked at 2 mg/L pollutant and declined afterwards. The activities of SOD, CAT and POD increased first and decreased afterwards except the activity of POD, which decreased with the increasing of Cd2+ concentration. Ultrastructural observation showed that the extent of ultrastructural damage was much more serious with higher pollutant concentration and longer time of stress. This resulted in swelling of chloroplast, disruption and disappearance of chloroplast membrane and disintegration of chloroplasts; swelling of cristae of mitochondria, deformation and vacuolization of mitochondria; condensation of chromatin in nucleus, dispersion of nucleolus and disruption of nuclear membrane. The experimental results showed: (1) Hg2+ and Cd2+ pollution not only destroyed physiological activities, but also caused irreversible damage to its ultrastructure, thus leading the cells to death; (2) With increase in the stress of Hg2+ and Cd2+, ultrastructural damage was related to the changes of plant physiology; (3) The toxic symptoms of plant showed an evident correlation between dose and effect; (4) The toxicity of Cd2+ on A. imbricata is heavier than that of Hg2+ under the same treatment time and concentration. The lethal concentration of Hg2+ to A. imbricata ranged from 3.5 to 4 mg/L, and that of Cd2+ ranged from 3 to 3.5 mg/L. The damage of cell ultrastructure on Anabaena azollae Strasburger was observed. The results indicated that tolerance of Azolla imbricata for Hg2+ and Cd2+ was higher than that of A. imbricata.

Effects of Heavy Metal Ions (Cu^(2+), Pb^(2+) and Cd^(2+)) on DNA Damage of the Gills, Hemocytes and Hepatopancreas of Marine Crab, Charybdis japonica

There are rising concerns about the hazardous effects of heavy metals on the environment. In this study, comet assay and DNA alkaline unwinding assay were conducted on the tissues (gills, hepatopancreas, and hemocytes) of Charybdis japonica in order to illustrate genotoxicity of three heavy metal ions (Cu2+, Pb2+, and Cd2+) on the marine crabs C. japonica. The crabs were exposed to Cu2+ (10, 50, and 100 ?g.L?1), Pb2+ (50, 250, and 500 ?g L?1) and Cd2+ (5, 25, and 50 ?g L?1), and the tissues were sampled at days 0.5, 1, 3, 6, 9, and 15. DNA alkaline unwinding assay was used for testing the DNA single strand break in gills and hepatopancreas and comet assay was employed for testing the DNA damage in hemocytes. The results showed that the DNA damage (F-value) of gills in the crabs exposed to the three heavy metals was decreased gradually during the exposure periods and there was a dose-time response relationship in certain time, suggesting that the levels of DNA single strand break in all the experimental groups increased significantly compared to the controls. Changes of F-value in hepatopancreas of the crabs exposed to the three heavy metals were similar to those in gills except that the peak values were found in the 500 ?g L?1 Pb2+ treatment group at day 3 and the 50 ?g L?1 Cd2+ treatment group at day 9. The ranks of DNA damage in gills and hepatopancreas induced by the three heavy metal ions (50 ?g L?1, day 15) were Cd2+ >Pb2+ >Cu2+ and Pb2+ >Cu2+ >Cd2+. The levels of DNA damage in gills were higher than those in hepatopancreas in the same experimental group. It can be concluded that indices of DNA damage can be used as the potential biomarkers of heavy metal pollution in marine environment.

Adsorption of Pb, Cd to Fe, Mn oxides in natural freshwater surface coatings developed in different seasons

Metal oxides(Fe, Mn oxides) in natural surface coatings(biofilms and associated minerals) are believed to play a significant role in the fate and transport of trace metal in aquatic environments. Seasonal variation of Fe, Mn oxides and organic materials in surface coatings, which were developed periodically on glass slides in Nanhu Lake, Jilin Province, China over the time frame of three seasons, was investigated in order to understand the influence of metal oxides on Pb and Cd adsorption to heterogeneous surface coating materials(biofilm). Pb and Cd adsorption was measured under controlled laboratory conditions(mineral salts solution with defined speciation, ionic strength 0 05 mol/L, 25℃ and pH 6 0). The classical Langmuir adsorption isotherm was applied to estimate equilibrium coefficients of Pb and Cd adsorption to the surface coatings. In general, components in the surface coatings varied greatly with seasons altering and obtained higher concentrations in summer while the content of iron oxides always exceeded that of manganese oxides. Correlation analyses between the maximum adsorption of Pb and Cd and components in the surface coatings developed periodically indicated that Pb phase association with Mn oxides and Cd phase association with Fe oxides as well as Mn oxides were statistically significant. Effect of Mn oxides on Cd adsorption was confirmed in view of its higher content in the surface coatings. The importance of ferromanganese oxides for Pb and Cd adsorption to the natural surface coatings developed in different seasons was evidenced.

Effect of Pb and Cd Stress on the Growth of Potato and Its Antioxidase System

With the potato variety Xishu 1 as the test materials, this paper adopted tissue culture to study the effect of Pb and Cd stress with different mass fractions on potato growth and the antioxidase system. The results showed that under the stress of Pb （200 mg/kg） and Cd （20 mg/kg）, growth of potato had no obvious difference with that in control group; under the stress of Pb （ 〉200 mg/kg） and Cd （ 〉20 mg/kg）, potato growth suspended, and its physiological indexes such as dry weight, plant height, root number, root length were inhibited obviously. With the increasing mass fraction of Pb, relative electrical conductivity, MDA and proline of potato leaves showed the tendency of increase, and the results in high mass fraction treatments showed significant difference with those in the control group （P 〈 0.05 ）, CAT, POD and SOD activity of leaves increased greatly with the increasing mass fraction. In the Pb stress treatment （200 mg/kg）, relative electrical conductivity, MDA and proline of potato leaves showed no obvious difference with those in the control group, and the results in high mass fraction treatments were significantly higher than those in the control group （ P 〈 O. 05 ）, CAT and SOD activity increased greatly with the increasing mass fraction （ P 〈 0.05 ）. Under the stress of Pb and Cd, synthesis of soluble protein in potato leaves was strongly inhibited. The results showed that potato was tolerant to Pb and Cd of lower mass fraction, and damage of potato caused by Pb and Cd stress could be relieved by improving activity of antioxidase and reducing peroxidation of membrane lipid, and the tolerance reduced with the increase of stress.

GLDA及其组合试剂对土壤中As、Cd、Cu和Pb的提取能力和机制

以重金属复合污染土壤为研究对象,将谷氨酸二乙酸四钠(GLDA)和其他生物可降解络合剂进行组合,研究了单一和组合试剂对土壤中不同重金属的提取效率和影响机制。结果表明:随着试剂与土壤重金属摩尔比的增加,重金属的提取率逐渐增加,最优摩尔比为5∶1;草酸(OA)对As、柠檬酸(CA)对Cu的提取能力高于乙二胺四乙酸二钠(EDTA)对As和Cu的提取能力;GLDA在偏酸的条件下对各种重金属的提取能力均较高;通过不同试剂的组合,GLDA和OA在摩尔比为1∶1时对土壤中As、Cu和Pb的提取能力最强,分别为52.4%、75.0%和89.8%,各重金属元素提取能力顺序为Pb>Cu≈Cd>As。而GLDA和CA在摩尔比为5∶1时对土壤中Cd的提取能力最强,为95.7%。提取前后的土壤重金属形态分级表明,GLDA+OA(1∶1)组合试剂降低了绝大多数形态的重金属含量,减少了易迁移和易被生物吸收的弱结合态重金属含量。

叶面阻控剂对大白菜Cu、Pb、Cd、As含量及产量的影响

土壤重金属污染已成为威胁农产品安全和人类健康的重要问题。为了验证喷施叶面阻控剂降低As-Cu复合污染土壤上大白菜重金属铜(Cu)、铅(Pb)、镉(Cd)、砷(As)的污染效应,在弥勒市选取有代表性的农田,通过田间试验研究了硅肥、铁肥、锌肥、硒肥对As-Cu复合污染土壤上的大白菜Cu,Pb,Cd,As含量及大白菜产量的影响。结果表明,与对照相比,喷施叶面阻控剂均有效降低了大白菜可食用部位Cu、Pb、Cd、As含量,降幅分别为13.32%~36.15%、25.31%~52.39%、14.75%~29.27%、33.55%~45.68%。喷施不同叶面阻控剂有效增加了大白菜产量,增幅为0.10%~3.20%,其中以喷施硅肥处理的白菜产量最高。综合不同阻控剂降低大白菜可食用部位Cu、Pb、Cd、As含量及对大白菜的增产效应,在本试验条件下,在以硅肥的喷施效果最佳。

石灰对土壤中Hg Cd Pb的植物可利用性的调控研究

通过盆栽试验,研究了石灰对污染土壤中Hg、Cd、Pb活性的影响及其在植物体内的积累效应。分析表明,石灰能降低或显著降低土壤中Hg、Cd、Pb的植物可利用性。随着石灰用量的增加,土壤Hg、Cd、Pb在植物体内含量呈下降的趋势。当石灰的施加量为22.5t·hm-2时,土壤中Hg、Cd的残留态明显增加,使植物吸收Hg、Cd量下降。

应用ICP-MS、AFS、GF-AAS测定食品中As、Cd、Hg、Pb方法的对比研究

应用ICP-MS法测定食品中的As、Cd、Hg、Pb,AFS法测定As、Hg,GF-AAS法测定Cd、Pb,并对3种测定方法进行对比研究。采用微波消解法作为ICP-MS法的样品前处理方法,湿式消解法作为AFS、GF-AAS法的前处理方法。通过优化消解条件,优化ICP-MS、AFS及GF-AAS仪器测定工作条件,选择适宜内标元素、EPA200.8标准干扰校正方程、硫脲-抗坏血酸掩蔽剂、硝酸镁-硝酸钯混合基体改进剂等办法,利用小麦粉(GBW08503b)和大米粉(GBW10010)国家标准物质验证各方法的准确度与可靠性。测定值均在标准值允许范围内,食品试样比对测定结果相对偏差均小于20%。ICP-MS法线性动态范围宽,不必稀释样品,适合批量样品多元素同时分析,但仪器昂贵、实验成本相对较高;AFS、GF-AAS法是单一元素分析,保证了测定结果准确、可靠,但由于线性范围窄,部分样品需要稀释,分析周期较长。

Effects of Combined Pollution of Pb and Cd on Growth and Yield of Rice

[Objective] The aim was to study the damage and the mechanism of combined pollution of Pb and Cd on rice growth,yield and quality of rice. [Method]Effects of combined pollution of Pb and Cd on the growth and yield of rice were studied by pot experiment with cultivating rice. [Result] Pb and Cd could promote rice growth at low concentration while inhibit plant height at high concentration; Pb and Cd stress reduced the number of rice tillers significantly,with the increasing of stress concentration,the decrease amplitude of the number of tillers was greater; the panicle per pot,seed setting rate,1 000-grain weight and yield of rice were reduced significantly by Pb and Cd stress,the grain number per panicle decreased significantly under low concentration of Pb and Cd but increased significantly under high concentration; the brown rice rate and milled rice rate increased significantly under low concentration of Pb and Cd while at high concentration of Pb and Cd,the both two reduced significantly,the head milled rice rate reduced significantly with the decreasing of concentration; The Pb and Cd content of grains were significantly positively related to the concentrations of Pb and Cd content in soil,it had excessively exceeded hygienic standard when the concentrations of Pb and Cd in soil were medium-high and the unqualified rate reached 333% and 122%. [Conclusion]The study had provided basis for the establishment of rice cultivation system in pollution areas.

GAS-LIQUID EQUILIBRIUM OF Pb-Cd-Zn SYSTEM UNDER VACUUM

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重金属离子Cd Hg Pb在鳗鱼体内残留规律研究

研究了0.005、0.05、0.10和0.15/mg/L四种不同浓度的Cd与0.10mg/LPb,0.05mg/LHg在日本鳗鱼肝脏、腮、鱼血和鱼肉的残留规律。分别将鳗鱼暴露于上述浓度的重金属35 d后再用清水喂养43 d,考察鳗鱼对该三种重金属的吸收和清除规律。结果显示三种重金属在鳗鱼体内富集能力依次是Hg>Pb>Cd。Cd在鳗鱼组织中蓄积顺序为肝脏>腮>鱼肉>血。鳗鱼体内Cd的吸收量与其暴露浓度呈正相关,停止暴露后Cd由其他组织向肝脏转移,可导致肝脏Cd负担持续增大。0.15mg/L浓度的Cd可使鳗鱼产生急性和亚急性中毒症状。鳗鱼组织中Hg和Pb蓄积顺序为腮>肝脏>鱼肉>血。鱼肉中两种重金属消除速度非常缓慢。

Compound pollution of Cd,Pb,Cu,Zn,and As on lowland rice

Cd,Pb,Cu,Zn,and As are typical pollutantsoriginated from Pb-Zn mine,smelting wastewater discharge/irrigation and gas emission,and they were distributed widely in China.Westudied the compound pollution of Cd,Pb,Cu,Zn,and As on rice. Pot culture and field plots test were bothused in the experiment.The treatments were:1)low dose:Cd 0.5,Pb 100,Cu 33,Zn 66,and As 10mg·kg;2)high dose:Cd 1.5,Pb 300,Cu 100,Zn 200,and As 30mg·kg,and 3)CK:no heavy metal was applied.Soil tested was meadow burozen(pH6.3-6.7)and the dosage of heavy metal added to the soilwas close to the soil environmental standard.Results were as follows:

常压湿式消解/常压微波消解-原子光谱法测定近海海洋生物体中Cu、Pb、Cd与Hg、As

采用常压湿式消解、常压微波消解两种方法处理近海海洋生物体,以石墨炉原子吸收法测定Cu、Pb、Cd和氢化物发生原子荧光法同时测定Hg、As。实验表明,以常压湿式消解法处理生物体,其Cu、Pb、Cd回收率分别为92%、103%、105%,而Hg、As的回收率分别是52%、58%。以常压微波消解法处理生物体,其Cu、Cd、Hg、As回收率分别为86%、94%、112%、94%,但用于Pb的测定,其回收率严重偏低。常压湿式消解、常压微波消解分别被用于海洋生物体样品中Cu、Pb、Cd和Hg、As的测定,有较好的测定结果。

水稻土中Hg,Cd,Pb和As的空间变异性特征及相关影响因素探讨——以四川孝泉地区为例

以四川孝泉地区水稻土为研究对象,利用地质统计学方法,系统地研究了水稻土中Hg,Cd,Pb和As含量的空间分布特征和空间变异性特征,就可能的影响因素进行讨论并得出结果:1)孝泉地区水稻土中Hg,Pb和As含量的空间自相关尺度分别为10.4km,3.8km和5.1km,且为中等程度相关;Cd在所研究的尺度上不表现明显的空间相关性。2)城镇生活、生产废弃物无序排放,铁路、公路运输,农业施肥、灌溉等因素对孝泉地区水稻土中Hg,Cd,Pb和As含量的空间变异性均有不同程度的影响。3)运用地质统计学方法处理多目标地球化学调查数据能有效地提取地球化学变量的空间结构信息并能在不同尺度上检验取样网度的合理性。

朱鹮羽毛中Ca,Mg,Pb,Cd,As和Hg六种元素测定

微量元素参与朱鹮体内的许多重要的生命过程,通过了解微量元素含量与朱鹮生长过程及生存环境有重要的联系,也有一些相关报道。文章用ICP和HG-AAS测定我国的朱鹮羽毛中营养性元素、有害元素Ca,Mg,Pb,Cd,As和Hg含量。结果表明,此方法简便、可靠,具有良好的精确度和准确性。通过较长时间对朱鹮羽毛中元素含量的跟踪研究,尤其对有害性元素含量的数据收集、整理和相关性研究,对于改善朱鹮的正常生长繁殖、发育以及生存环境状况是有价值的。

农产品中Zn、Cu、Fe、Pb、Cd、Cr、Hg、As的快速测定

建立了微波消解法一次前处理,电感耦合等离子体发射光谱(ICP-AES)法、石墨炉原子吸收光谱(GF-AAS)法和氢化物-原子荧光光谱(HG-AFS)法相结合联合快速测定农产品中Zn、Cu、Fe、Pb、Cd、Cr、As、Hg等重金属元素的方法。ICP-AES法采用基体匹配法消除对Zn、Cu、Fe的干扰,GF-AAS法采用氘等扣背景和加入机体改进剂消除测定Pb、Cd、Cr的干扰,HG-AFS法采用加入硫脲和抗坏血酸消除同时测定As和Hg的干扰。该方法对7种元素的检出限分别为0.009,0.00024,0.0016,0.001,0.0001,0.001,0.0005,0.00004mg/L,RSD为2.2%～4.9%,白菜样品的回收率为95%～112%。

ICP-MS测定化肥中有害元素Cr、Cd、As、Pb、Hg的新方法

采用电感耦合等离子体质谱法测定化肥中微量Cr、Cd、As、Pb、Hg元素。样品经微波消解和敞开酸溶,滴加5～8滴2%高锰酸钾氧化,低温水浴加热蒸至近干,加甲醇2 mL溶剂化,用水定容至100 mL,进行测定。方法标准加入回收率为67%～115%,RSD小于15%,误差完全符合GB18877-2002的规定要求,方法简便快速。

Reduction of Cd, Cu, Ni and Pb Mobility by Active Si

A series of column experiments were performed to investigate the mechanisms of silicon （Si） and heavy metals （HM） interaction in the soil. The column experiments were conducted with Gray Forest Soil treated by various forms of active Si （diatomaceous earth, zeolite, amorphous silicon dioxide and concentrated monosilicic acid） in environment polluted conditions with soluble salts of Cd, Cu, Ni and Pb. All Si-rich substances used in the test were analyzed with electron scan microscope. The results of HM immobilization in soil by Si-rich materials showed that diatomaceous earth and concentrated monosilicic acid immobilized HM better than zeolite and amorphous silicon dioxide. The reductions in HM mobility were re- alized by the reaction between monosilicic acid and HM in soil solution and by adsorption of HM on Si-rich surface. The intensity of HM movement through soil depended on the type of HM. The maximum reduction of HM mobility with application of Si-rich substances was obtained for Cd and Ni and less effect was observed for Cu and Pb.

Removal of Cd(Ⅱ)and Pb(Ⅱ)from soil through desorption using citric acid:Kinetic and equilibrium studies

The desorption test was conducted to evaluate the desorption behavior of Pb(Ⅱ)and Cd(Ⅱ)using citric acid.The influential factors that were considered included initial Pb(Ⅱ),Cd(Ⅱ)contamination levels in soil,concentration of citric acid,reaction time,soil pH value and ionic strength.The test results indicated that the desorption was a rapid reaction(less than 6 h),and the removal percentages of Cd(Ⅱ)and Pb(Ⅱ)increased with the increasing contamination levels,concentration of citric acid and the addition of Na^+,Ca^(2+),Na^+, Cl~– and the chelating of organic ligands.

Characteristics of Uptake and Accumulation of Pb and Cd in Osmanthus fragrans(Thunb.) Lour.under Single and Combined Stresses of Pb and Cd

[Objective] This study aimed to investigate the characteristics of Pb and Cd uptake and accumulation in Osmanthus fragrans（Thunb.） Lour.under single and combined stress of Pb and Cd.[Method] Pot experiment was adopted with O.fragrans seedlings as experimental materials to investigate the effect of single and combined stresses of Pb and Cd on the growth of O.fragrans seedlings under 0,50,100,500,1 000 and 2 000 mg/kg of Pb and 0,1,10,50,100 and 200 mg/kg of Cd.[Result] Under the experimental conditions,the growth of O.fragrans seedlings was significantly inhibited under moderate Pb stress（500 mg/kg） and high Cd stress（100 mg/kg）;the decreasing order of Pb uptake rate of different O.fragrans tissues was root stem leaf;the decreasing order of Cd content of different O.fragrans tissues was root stem leaf,while the decreasing order of Cd uptake rate of different O.fragrans tissues was stem root leaf.[Conclusion] Under combined stress,low concentrations of Pb and Cd can mutually promote the uptake and accumulation,while high concentrations of Pb and Cd can mutually inhibit the uptake and accumulation.