Effect of heavy metals (Cd, Cu) on the gametophytes of Laminaria japonica Aresch

Effects of various concentrations of two heavy metals, namely Cd and Cu, on gametophytes of Laminaria japonica Aresch were determined by recording morphological changes of gametophytes, determining pH values and the heavy metal content of the culture solution, calculating the germination rate of sporophytes, and observing heavy metal (Cd) distribution using a fluorescence microscope. The results showed that heavy metals damaged the gametophytes, and were even lethal, and that the higher the concentration of heavy metal ions, the greater the injury to gametophytes. Gametophytes could not survive in culture solutions containing more than 100 mg/L Cd and 50 mg/L Cu and were only able to survive in culture solution containing a mixture of Cd and Cu tip to a concentration of 10 mg/L, which indicates that gametophytes have a higher tolerance to Cd than Cu and that multiple heavy metal ions in solution markedly aggravate the damage to gametophytes compared with individual heavy metal ions. With increases in the concentration of the heavy metal, the burgeoning rate of sporophytes decreased acutely, and solutions containing multiple heavy metal ions caused even more marked harm to sporophytes than solutions containing a single heavy metal ion, because most sporophytes died in mixed solutions. The pH value of the culture medium dropped immediately at the beginning (the first day) of treatment, increased over the following days, and then decreased again. The pH of culture media containing multiple heavy metal ions showed greater variation than media containing a single heavy metal ion, with the extent of the decrease in pH of culture media containing multiple ions being greatest during the last period of the experiment. With increases in the concentration of heavy metals, the capacity of gametophytes to accumulate these ions increased. The blue fluorescent light emitted by the Cd- and Cd-binding protein complex existing in gametophytes in media containing different concentrations of Cd showed clearly the distribution of the ion in gametophytes and the results obtained were consistent with distribution determined using other methods. All results of the present study showed that gametophytes of L. japonica play a remarkable role as heavy metal decontaminators, especially with regard to Cd.

Sorption and desorption of Cu and Cd by macroalgae and microalgae

The sorption and desorption of Cu and Cd by two species of brown macroalgae and five species of microalgae were studied. The two brown macroalgae, Laminaria japonica and Sargassum kjellmanianum, were found to have high capacities at pHs between 4.0 and 5.0 while for microalgae, optimum pH lay at 6.7. The presence of other cations in solution was found to reduce the sorption of the target cation, suggesting a competition for sorption sites on organisms. Sorption isotherms obeyed the Freundlich equation, suggesting involvement of a multiplicity of mechanisms and sorption sites. For the microalgae tested, Spirulina platensis had the highest capacity for Cd, followed by Nannochloropsis oculata, Phaeodactylum tricornutum, Platymonas cordifolia and Chaetoceros minutissimus. The reversibility of metal sorption by macroalgae was examined and the results show that both HCl and EDTA solutions were very effective in desorbing sorbed metal ions from macroalgae, with up to 99.5% of metals being recovered. The regenerated biomass showed undiminished sorption performance for the two metals studied, suggesting the potential of such material for use in water and wastewater treatment. (C) 1998 Elsevier Science Ltd. All rights reserved.

Studies on two coordination polymers [M(mu(4)-pz25dc)](n) (M = Cd or Zn, pz25dc=pyrazine-2,5-dicarboxylato) with three-dimensional pillared-layer three-nodal framework: Synthesis, structural characterization, strong optical non-linearities and optical limiting properties

Two isomorphous new candidates [M(mu(4)-pz25dc)](n) (M = Cd, 1; Zn, 2; pz25dc = pyrazine-2,5-dicarboxylato)for nonlinear optical (NLO) materials have been synthesized hydrothermally and characterized crystallographically as pillared-layer three-nodal frameworks with one four-connected metal nodes and two crystallographically different four-connected ligand nodes. Their optical non-linearities are measured by the Z-Scan technique with an 8 ns pulsed laser at 532 nm. These two coordination polymers both exhibit strong NLO absorptive abilities [alpha(2) = (63 +/- 6) x 10 (12) mW (1) 1, ( 46 +/- 6) x 10 (11) mW (1) 2] and effective self-focusing performance [n(2) = (67 +/- 5) x 10 (18) 1, (13 +/- 3) x 10 (18) m(2) W (1) 2] in 1.02 x 10 (4) 1 and 1.05 x 10 (4) mol dm (3) 2 DMF solution separately. The values of the limiting threshold are also measured from the optical limiting experimental data. The heavy atom effect plays important role in the enhancement of optical non-linearities and optical limiting properties. (C) 2009 Elsevier B. V. All rights reserved.

土法炼锌导致Cd对土壤-农作物系统污染的研究

采用现场取样及室内分析方法，研究了贵州省赫章县的土法炼锌活动导致Cd对当地土壤-农作物系统的污染状况及规律。结果表明，炼锌污染土壤Cd含量高达5．3～144．7mg·k^-1，且Cd在土壤中的累积程度随着冶炼时间的增长而加剧。形态分析结果显示，土壤中的CaCl2和DTPA提取态Cd分别占全量的2．47％～16．80％和3．18％～10．11％，随着Cd在土壤中累积时间的加长，CaCl2和DTPA提取态Cd的百分含量均呈显著下降趋势。土壤污染导致农作物体内Cd的明显蓄积，玉米、土豆和大豆三类当地主要农作物可食部分Cd含量分别为1．8、4．8和2．0mg·kg^-1，分别超过国家粮食卫生标准9、24和10倍。相关分析结果显示，CaCl2提取态Cd与农作物中Cd含量没有相关关系，而DTPA提取态Cd和全量Cd与农作物根和茎叶中Cd含量显著正相关。

简化连续提取法评价污染土壤中Zn、Cd的植物有效性

以0．01mol·L^-1 CaCl2和0．005mol·L^-1 1DTPA作为提取剂，用简化的3步连续提取法对贵州省赫章县土法炼锌污染土壤中Zn、Cd的形态进行了分析．结果显示，污染土壤中Zn、Cd主要以残渣态的形式存在，CaCl2提取态和DTPA提取态Zn、CA平均仅占全量的0．63%、3．91％和lO．94％、10．13％．土壤中不同形态Zn、Cd含量与玉米中Zn、CA含量的相关分析结果显示，CaCl2提取态金属与玉米中金属含量投有显著的相关关系，而DTPA提取态、残渣态以及总量Zn、Cd与玉米根、茎叶中Zn、Cd含量显著正相关．这些结果表明CaCl2提取态Zn、Cd对土壤中该元素的植物有效态可能不具重要贡献，而DTPA提取态金属和金属总量在一定程度上能作为评价土壤中元素植物有效性的标准．

海南土壤中Zn、Pb、Cu、Cd四种重金属含量及其生物有效性的研究

对海南63 个土壤样品中的Zn、Pb、Cu、Cd 四种重金属的总量和生物有效态含量以及45 个植物样(根、茎、叶) 中的重金属含量分别进行了测定,采样点基本上覆盖了海南全省,测定结果表明,土壤中Zn 总量低于全国平均值,而Pb、Cu、Cd 高于全国平均值,土壤中重金属生物有效态含量一般低于其总量的10 % ,其中Pb 最高为7. 71 % ,而Cu 仅为1. 13 % ,具有较大的变异性;植物中重金属含量与土壤中重金属总量呈现负相关性,但与土壤中有效态重金属含量一般呈现正相关性,叶中的重金属含量与土壤中有效态重金属含量之间的相关性更为显著,叶中的重金属含量与土壤中有效态重金属含量之间的相关系数分别为: Zn (01726) ,Cu (01626) , Pb(01774) ,Cd(01512) 。这说明土壤中重金属总量并不能全面的评价土壤的环境效应和重金属的生物有效性,应该把重金属总量和生物有效态含量结合起来加以研究,并应将土壤中重金属的含量与植物中该元素含量之间作相关分析,根据其相关系数的大小来判断其生物有效性的程度。

扬子地块西南缘铅锌矿床Cd、Ge与Ga富集规律初步研究

扬子地块西南缘分布着大量富含Cd、Ge与Ga的铅锌矿床，已成为我国Pb、Zn及Cd、Ge与Ga矿产资源的重要生产基地。对代表性铅锌矿床进行野外地质调查和系统采样鉴定后．应用电子探针微区分析手段，研究主要矿石矿物闪锌矿、方铅矿和黄铁矿中分散元素的富集特征。结果显示．各类矿床中闪锌矿均相对富集Cd，方铅矿富集Ge与Ga，而黄铁矿中Cd、Ge与Ga的富集系数均相对较低．未呈现出选择性富集的趋势；赋存于震旦纪一寒武纪地层且以脉状、网脉状产出的矿体中闪锌矿的Cd含量明显高于赋存于晚古生代并以层状产出的矿体中闪锌矿的Cd含量。

Cd的分析测试方法综述

通过对近10年来Cd的分析方法的归纳总结,分别讨论了容量法、原子吸收法、分光光度法及原子荧光法……等方法测定Cd的灵敏度、准确度、精密度以及适用范围,建议在实际工作中根据样品的数量和性质、含Cd量的高低以及其他测定的特殊要求,选择合适的分析方法.