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Sample records for cd pb zn

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

    Institute of Scientific and Technical Information of China (English)

    WUYanyu; WANGXin

    1999-01-01

    Cd, Pb, Cu, Zn, and As are typical pollutants originated from Pb-Zn mine, smelting waste water discharge/irrigation and gas emission,and they were distributed widely in China. We studied the compound pollution of Cd, Pb,Cu, Zn, and As on rice.

  2. Pb and Zn accumulation in a Cd-hyperaccumulator (Viola baoshanensis).

    Science.gov (United States)

    Wu, Chuan; Liao, Bin; Wang, Sheng-Long; Zhang, Jun; Li, Jin-Tian

    2010-08-01

    Viola baoshanensis has been identified as a Cd-hyperaccumulator, however, its ability to accumulate Pb or Zn is less certain. Therefore, this study focused on determining whether or not V. baoshanensis can accumulate Pb or Zn, by means of field survey, hydroponic and pot experiments. In addition, we also tried to obtain further information on the Cd hyperaccumulating characteristics of this species. Under field conditions, V. baoshanensis accumulated on average 1090 mg Cd kg(-1), 1902 mg Pb kg(-1) and 3428 mg Zn kg(-1) in its shoots, respectively. In hydroponic and pot experiments, V. baoshanensis showed high tolerance to Cd, Pb, and Zn, as well as the ability to accumulate exceptionally high concentrations of the three elements in its shoots (> 2% Cd, > 1% Pb, and > 0.5% Zn on a dry matter basis). These results, taken together, suggested that V. baoshanensis is not only a Cd-hyperaccumulator, but also a strong accumulator of Pb and Zn. PMID:21166282

  3. Bioleaching mechanism of Zn, Pb, In, Ag, Cd and As from Pb/Zn smelting slag by autotrophic bacteria.

    Science.gov (United States)

    Wang, Jia; Huang, Qifei; Li, Ting; Xin, Baoping; Chen, Shi; Guo, Xingming; Liu, Changhao; Li, Yuping

    2015-08-15

    A few studies have focused on release of valuable/toxic metals from Pb/Zn smelting slag by heterotrophic bioleaching using expensive yeast extract as an energy source. The high leaching cost greatly limits the practical potential of the method. In this work, autotrophic bioleaching using cheap sulfur or/and pyrite as energy matter was firstly applied to tackle the smelting slag and the bioleaching mechanisms were explained. The results indicated autotrophic bioleaching can solubilize valuable/toxic metals from slag, yielding maximum extraction efficiencies of 90% for Zn, 86% for Cd and 71% for In, although the extraction efficiencies of Pb, As and Ag were poor. The bioleaching performance of Zn, Cd and Pb was independent of leaching system, and leaching mechanism was acid dissolution. A maximum efficiency of 25% for As was achieved by acid dissolution in sulfursulfur oxidizing bacteria (S-SOB), but the formation of FeAsO4 reduced extraction efficiency in mixed energy source - mixed culture (MS-MC). Combined works of acid dissolution and Fe(3+) oxidation in MS-MC was responsible for the highest extraction efficiency of 71% for In. Ag was present in the slag as refractory AgPb4(AsO4)3 and AgFe2S3, so extraction did not occur. PMID:25996622

  4. Comparison of the Molecular Interaction Volume Model with the Wagner Formulae in the Zn-Pb-In and Zn-Sn-Cd-Pb Dilute Solutions

    Institute of Scientific and Technical Information of China (English)

    Dongping TAO; Zhuo CHEN; Dunfang LI; Yifeng GAO; Qianghua SHEN

    2004-01-01

    The coordination numbers in the molecular interaction volume model (MIVM) can be calculated from the common physical quantities of pure liquid metals. A notable feature of the model lie in its capability to predict the thermodynamic properties of solutes in the Zn-Pb-ln and Zn-Sn-Cd-Pb dilute solutions using only the binary infinite dilute activity coefficients, and the predicted values are in good agreement with the experimental data of the dilute solutions.

  5. Role of microbial inoculation and chitosan in phytoextraction of Cu, Zn, Pb and Cd by Elsholtzia splendens - a field case

    Energy Technology Data Exchange (ETDEWEB)

    Wang Fayuan [Agricultural College, Henan University of Science and Technology, 70 Tianjin Road, Luoyang, Henan Province 471003 (China) and Institute of Soil Science, Chinese Academy of Sciences, Nanjing, Jiangsu Province 210008 (China)]. E-mail: wfy1975@163.com; Lin Xiangui [Institute of Soil Science, Chinese Academy of Sciences, Nanjing, Jiangsu Province 210008 (China); Yin Rui [Institute of Soil Science, Chinese Academy of Sciences, Nanjing, Jiangsu Province 210008 (China)

    2007-05-15

    A field experiment was carried out to study the effect of microbial inoculation on heavy metal phytoextraction by Elsholtzia splendens and whether chitosan could have a synergistic effect with the microbial inocula. The microbial inocula consisted of a consortium of arbuscular mycorrhizal fungi and two Penicillium fungi. Three treatments were included: the control, inoculation with microbial inocula, and the inoculation combined with chitosan. Microbial inoculation increased plant biomass especially shoot dry weight, enhanced shoot Cu, Zn and Pb concentrations but did not affect Cd, leading to higher shoot Cu, Zn, Pb and Cd uptake. Compared with microbial inoculation alone, chitosan application did not affect plant growth but increased shoot Zn, Pb and Cd concentrations except Cu, which led to higher phytoextraction efficiencies and partitioning to shoots of Zn, Pb and Cd. These results indicated synergistic effects between microbial inocula and chitosan on Zn, Pb and Cd phytoextraction. - Co-application of microbial inocula and chitosan enhanced heavy metal phytoextraction by E. splendens.

  6. Role of microbial inoculation and chitosan in phytoextraction of Cu, Zn, Pb and Cd by Elsholtzia splendens - a field case

    International Nuclear Information System (INIS)

    A field experiment was carried out to study the effect of microbial inoculation on heavy metal phytoextraction by Elsholtzia splendens and whether chitosan could have a synergistic effect with the microbial inocula. The microbial inocula consisted of a consortium of arbuscular mycorrhizal fungi and two Penicillium fungi. Three treatments were included: the control, inoculation with microbial inocula, and the inoculation combined with chitosan. Microbial inoculation increased plant biomass especially shoot dry weight, enhanced shoot Cu, Zn and Pb concentrations but did not affect Cd, leading to higher shoot Cu, Zn, Pb and Cd uptake. Compared with microbial inoculation alone, chitosan application did not affect plant growth but increased shoot Zn, Pb and Cd concentrations except Cu, which led to higher phytoextraction efficiencies and partitioning to shoots of Zn, Pb and Cd. These results indicated synergistic effects between microbial inocula and chitosan on Zn, Pb and Cd phytoextraction. - Co-application of microbial inocula and chitosan enhanced heavy metal phytoextraction by E. splendens

  7. Chemical behavior of Cu, Zn, Cd, and Pb in a eutrophic reservoir: speciation and complexation capacity.

    Science.gov (United States)

    Tonietto, Alessandra Emanuele; Lombardi, Ana Teresa; Choueri, Rodrigo Brasil; Vieira, Armando Augusto Henriques

    2015-10-01

    This research aimed at evaluating cadmium (Cd), copper (Cu), lead (Pb), and zinc (Zn) speciation in water samples as well as determining water quality parameters (alkalinity, chlorophyll a, chloride, conductivity, dissolved organic carbon, dissolved oxygen, inorganic carbon, nitrate, pH, total suspended solids, and water temperature) in a eutrophic reservoir. This was performed through calculation of free metal ions using the chemical equilibrium software MINEQL+ 4.61, determination of labile, dissolved, and total metal concentrations via differential pulse anodic stripping voltammetry, and determination of complexed metal by the difference between the total concentration of dissolved and labile metal. Additionally, ligand complexation capacities (CC), such as the strength of the association of metals-ligands (logK'ML) and ligand concentrations (C L) were calculated via Ruzic's linearization method. Water samples were taken in winter and summer, and the results showed that for total and dissolved metals, Zn > Cu > Pb > Cd concentration. In general, higher concentrations of Cu and Zn remained complexed with the dissolved fraction, while Pb was mostly complexed with particulate materials. Chemical equilibrium modeling (MINEQL+) showed that Zn(2+) and Cd(2+) dominated the labile species, while Cu and Pb were complexed with carbonates. Zinc was a unique metal for which a direct relation between dissolved species with labile and complexed forms was obtained. The CC for ligands indicated a higher C L for Cu, followed by Pb, Zn, and Cd in decreasing amounts. Nevertheless, the strength of the association of all metals and their respective ligands was similar. Factor analysis with principal component analysis as the extraction procedure confirmed seasonal effects on water quality parameters and metal speciation. Total, dissolved, and complexed Cu and total, dissolved, complexed, and labile Pb species were all higher in winter, whereas in summer, Zn was mostly present in the

  8. Simultaneous recovery of heavy metals (Pb, Cd, Zn from diluted solutions by electroextraction technique

    Directory of Open Access Journals (Sweden)

    Smara A.

    2013-04-01

    Full Text Available Cadmium is mainly used in galvanoplasty and stabilisation of plastic materials. It accumulates continuously in soils. The analysis of soil samples gave concrete evidence of increase of concentration of this element during the past centunary [1]. Furthermore Cd and Pb attack selectively the kidneys and the liver with enzymatic troubles. The work has enabaled to put into evidence the contribution of the presence of resin to the conventional electrodialysis process. The optimal conditions for the elimination of Cd++, Zn++ and Pb++ ions were determined. These included influence of resin, imposed current density, flow rate of the feeding solution (diluat, different supporting electrolytes used during the electroextraction (HNO3, HCl and H2SO4 and concentration of the solution to be treated [2-3-4]. Furthermore the competition between the electroextraction of the metallic cations Cd++, Zn++and Pb++ was investigated for different mixtures.

  9. Accumulation dynamics and cellular locations of Pb, Zn and Cd in resident and transplanted Flavocetraria nivalis lichens near a former Pb-Zn mine

    DEFF Research Database (Denmark)

    Søndergaard, Jens

    2013-01-01

    Accumulation dynamics and cellular locations of lead (Pb), zinc (Zn) and cadmium (Cd) were studied in Flavocetraria nivalis lichens near the former Black Angel Pb-Zn Mine in West Greenland. Natural resident thalli were collected from four dust-contaminated sites near the mine. In addition, thalli...... were taken from an uncontaminated reference site and transplanted to the contaminated sites followed by a collection 1 year after. Total thalli metal contents were determined, and thalli were subjected to a sequential extraction procedure. After 1 year of transplantation, total Pb thalli contents were...... sequential extraction procedure showed marked differences among Pb, Zn and Cd in the extracellular, intracellular and residual fraction. The lower total metal concentrations in transplanted compared with resident thalli at the contaminated sites were mostly due to a larger metal content bound in the residual...

  10. Role of Bound Zn(II) in the CadC Cd(II)/Pb(II)/Zn(II)-Responsive Repressor

    Energy Technology Data Exchange (ETDEWEB)

    Kandegedara, A.; Thiyagarajan, S; Kondapalli, K; Stemmler, T; Rosen, B

    2009-01-01

    The Staphylococcus aureus plasmid pI258 cadCA operon encodes a P-type ATPase, CadA, that confers resistance to Cd(II)/Pb(II)/Zn(II). Expression is regulated by CadC, a homodimeric repressor that dissociates from the cad operator/promoter upon binding of Cd(II), Pb(II), or Zn(II). CadC is a member of the ArsR/SmtB family of metalloregulatory proteins. The crystal structure of CadC shows two types of metal binding sites, termed Site 1 and Site 2, and the homodimer has two of each. Site 1 is the physiological inducer binding site. The two Site 2 metal binding sites are formed at the dimerization interface. Site 2 is not regulatory in CadC but is regulatory in the homologue SmtB. Here the role of each site was investigated by mutagenesis. Both sites bind either Cd(II) or Zn(II). However, Site 1 has higher affinity for Cd(II) over Zn(II), and Site 2 prefers Zn(II) over Cd(II). Site 2 is not required for either derepression or dimerization. The crystal structure of the wild type with bound Zn(II) and of a mutant lacking Site 2 was compared with the SmtB structure with and without bound Zn(II). We propose that an arginine residue allows for Zn(II) regulation in SmtB and, conversely, a glycine results in a lack of regulation by Zn(II) in CadC. We propose that a glycine residue was ancestral whether the repressor binds Zn(II) at a Site 2 like CadC or has no Site 2 like the paralogous ArsR and implies that acquisition of regulatory ability in SmtB was a more recent evolutionary event.

  11. Accumulation of Pb, Cd, Cu and Zn in plants and hyperaccumulator choice in Lanping lead-zinc mine area, China.

    Science.gov (United States)

    Yanqun, Zu; Yuan, Li; Schvartz, Christian; Langlade, Laurent; Fan, Liu

    2004-06-01

    A field survey of higher terrestrial plants growing on Lanping lead-zinc mine, China were conducted to identify species accumulating exceptionally large concentrations of Pb, Cd, Cu and Zn of 20 samples of 17 plant species. Concentrations of Pb and Zn in soil and in plant were higher than that of Cu and Cd. Significant difference was observed among the average concentrations of four heavy metals in plants (except Cd and Cu) and in soil (except Pb and Zn) (Ptree>herbaceous, and herbaceous grew in soil with the highest concentrations of four heavy metals. In different areas, the concentrations of Pb, Cd, Cu and Zn in plants and soils and enrichment coefficient were different. Plants in Paomaping had more accumulating ability to Pb, Cd and Zn, and plants in Jinfeng River had more accumulating ability to Cu. Six plant species, i.e. S. cathayana, Lithocarpus dealbatus, L. plyneura, Fargesia dura, Arundinella yunnanensis and R. annae in Paomaping, had high accumulation capacity. R. annae in Paomaping had hyperaccumulating capacity to Pb, Cd and Zn, L. plyneura to Pb and Cd, and S. cathayana to Cd, respectively. PMID:15031017

  12. Removal of Cd, Cu, Pb, and Zn from aqueous solutions by biochars.

    Science.gov (United States)

    Doumer, M E; Rigol, A; Vidal, M; Mangrich, A S

    2016-02-01

    Sorption and desorption of heavy metals (Cd, Cu, Pb, and Zn) was evaluated in biochars derived from sugarcane bagasse (SB), eucalyptus forest residues (CE), castor meal (CM), green coconut pericarp (PC), and water hyacinth (WH) as candidate materials for the treatment of contaminated waters and soils. Solid-liquid distribution coefficients depended strongly on the initial metal concentration, with K d,max values mostly within the range 10(3)-10(4) L kg(-1). For all biochars, up to 95 % removal of all the target metals from water was achieved. The WH biochar showed the highest K d,max values for all the metals, especially Cd and Zn, followed by CE (for Cd and Pb) and PC (for Cd, Pb, and Zn). Sorption data were fitted satisfactorily with Freundlich and linear models (in the latter case, for the low concentration range). The sorption appeared to be controlled by cationic exchange, together with specific surface complexation at low metal concentrations. The low desorption yields, generally less than 5 %, confirmed that the sorption process was largely irreversible and that the biochars could potentially be used in decontamination applications. PMID:26438367

  13. EFFECTS OF AQUEOUS AL, CD, CU, FE(II), NI, AND ZN ON PB IMMOBILIZATION BY HYDROXYAPATITE

    Science.gov (United States)

    The effects of aqueous Al, Cd, Cu, Fe(II), Ni, or Zn on Pb immobilization by hydroxyapatite (Ca10(PO4),(OH)2) were studied. ead was removed mainly via hydroxyapatite dissolution and hydroxypyromorphite (Pb10(PO4)6(OH)2) precipitation in the presence of these metals with a Pb remo...

  14. Atmospheric Deposition of Pb, Zn, Cu, and Cd in Amman, Jordan

    International Nuclear Information System (INIS)

    Atmospheric samples were collected by high-volume air sampler and dust fall containers during the summer of 1995 at different sites in Amman City, Jordan. Heavy metal contents in settle able (dust fall) as well as in air particulates (suspended) were analyzed by graphite furnace atomic absorption spectrophotometry. The atmospheric concentrations of Zn, Cu, Pb, and Cd were 344, 170, 291, and 3.8 ng/m3 , respectively. On the other hand, the levels of these elements in dust fall deposition were 505, 94, 74, and 3.1 μg/g, respectively. The fluxes and dry deposition velocities of these heavy metals were determined and compared with the findings of other investigators worldwide. Significant enrichment coefficients of heavy metals in dust fall were observed. The enrichment coefficients were 12.1, 6.1, 11.7, and 1.1 for Zn, Cu, Pb, and Cd, respectively

  15. Environmental pollution study by Hg, Pb, Cd, and Zn in Chetumal bay, Quintana Roo, Mexico

    International Nuclear Information System (INIS)

    The environmental pollution by heavy metals in Chetumal Bay was studied, quantifying mercury, lead, cadmium and zinc concentrations in mussels tissue (Mytilopsis sallei) and sea sediments by collecting samples in two seasons of the year (drought and rainy). Moreover, determining the motion of Cd, Pb and Zn in sediments using a BCR's sequential extraction scheme and identifying the different mineral phases by X-ray diffraction. From this study, it was observed that the Pb, Cd and Zn concentrations were lower in mussels than sediments. However the concentrations profiles for these metals are similar in mussels and sediments. Statistical correlations from the results are presented and discussed. The results obtained are in good agreement with published values for polluted sediments

  16. RELATIONSHIPS BETWEEN FRACTIONATIONS OF Pb, Cd, Cu, Zn AND Ni AND SOIL PROPERTIES IN URBAN SOILS OF CHANGCHUN, CHINA

    Institute of Scientific and Technical Information of China (English)

    GUO Ping; XIE Zhong-lei; LI Jun; KANG Chun-li; LIU Jian-hua

    2005-01-01

    An extensive soil investigation was conducted in different domains of Changchun to disclose the fractionations of Pb, Cu, Cd, Zn and Ni in urban soils. Meanwhile correlation analysis and multiple stepwise regressions were used to define relationships between soil properties and metal fractions and the chief factors influencingthe fractionation of heavy metals in the soils. The results showed that Pb, Ni and Cu were mainly associated with the residual and organic forms; most of Cd was concentrated in the residual and exchangeable fractions. Zn in residual and carbonate fraction was the highest. The activities of the heavy metals probably declined in the following order: Cd, Zn,Pb, CuandNi. The chemical fractions of heavy metals in different domains in Changchun City were of significantly spatial heterogeneity. Soil properties had different influences on the chemical fractions of heavy metals to some extent and the main factors influencing Cd, Zn, Pb, Cu and Ni fractionation and transformation were apparently different.

  17. Atmospheric deposition of heavy metals (Cu, Zn, Cd and Pb) in Varanasi City, India.

    Science.gov (United States)

    Sharma, Rajesh Kumar; Agrawal, Madhoolika; Marshall, Fiona M

    2008-07-01

    Rapid growth in urbanization and industrialization in developing countries may significantly contribute in heavy metal contamination of vegetables through atmospheric depositions. In the present study, an assessment was made to investigate the spatial and seasonal variations in deposition rates of heavy metals and its contribution to contamination of palak (Beta vulgaris). Samples of bulk atmospheric deposits and Beta vulgaris for analysis of Cu, Zn, Cd and Pb were collected from different sampling locations differing in traffic density and land use patterns. The results showed that the sampling locations situated in industrial or commercial areas with heavy traffic load showed significantly elevated levels of Cu, Zn and Cd deposition rate as compared to those situated in residential areas with low traffic load. The deposition rates of Cu, Zn and Cd were significantly higher in summer and winter as compared to rainy season, however, Pb deposition rate was significantly higher in rainy and summer seasons as compared to winter season. Atmospheric depositions have significantly elevated the levels of heavy metals in B. vulgaris collected during evening as compared to those collected in morning hours. The study further showed that local population has maximum exposure to Cd contamination through consumption of B. vulgaris. The present study clearly points out the urban and industrial activities of a city have potential to elevate the levels of heavy metals in the atmospheric deposits, which may consequently contaminate the food chain and thus posing health risk to the local population. PMID:17879134

  18. Electrokinetic enhancement on phytoremediation in Zn, Pb, Cu and Cd contaminated soil using potato plants.

    Science.gov (United States)

    Aboughalma, Hanssan; Bi, Ran; Schlaak, Michael

    2008-07-01

    The use of a combination of electrokinetic remediation and phytoremediation to decontaminate soil polluted with heavy metals has been demonstrated in a laboratory-scale experiment. Potato tubers were planted in plastic vessels filled with Zn, Pb, Cu and Cd contaminated soil and grown in a greenhouse. Three of these vessels were treated with direct current electric field (DC), three with alternative current (AC) and three remained untreated as control vessels. The soil pH varied from anode to cathode with a minimum of pH 3 near the anode and a maximum of pH 8 near the cathode in the DC treated soil profile. There was an accumulation of Zn, Cu and Cd at about 12 cm distance from anode when soil pH was 5 in the DC treated soil profile. There was no significant metal redistribution and pH variation between anode and cathode in the AC soil profile. The biomass production of the plants was 72% higher under AC treatment and 27% lower under DC treatment compared to the control. Metal accumulation was generally higher in the plant roots treated with electrical fields than the control. The overall metal uptake in plant shoots was lower under DC treatment compared to AC treatment and control, although there was a higher accumulation of Zn and Cu in the plant roots treated with electrical fields. The Zn uptake in plant shoots under AC treatment was higher compared to the control and DC treatment. Zn and Cu accumulation in the plant roots under AC and DC treatment was similar, and both were higher comparing to control. Cd content in plant roots under all three treatments was found to be higher than that in the soil. The Pb accumulation in the roots and the uptake into the shoots was lower compared to its content in the soil. PMID:18569305

  19. Biosorption of divalent Pb, Cd and Zn on aragonite and calcite mollusk shells

    Energy Technology Data Exchange (ETDEWEB)

    Du Yang; Lian Fei [Key Laboratory of Pollution Process and Environmental Criteria, Ministry of Education, Tianjin Key Laboratory of Urban Ecology Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai University, Tianjin 300071 (China); Zhu Lingyan, E-mail: zhuly@nankai.edu.cn [Key Laboratory of Pollution Process and Environmental Criteria, Ministry of Education, Tianjin Key Laboratory of Urban Ecology Environmental Remediation and Pollution Control, College of Environmental Science and Engineering, Nankai University, Tianjin 300071 (China)

    2011-07-15

    The potential of using mollusk shell powder in aragonite (razor clam shells, RCS) and calcite phase (oyster shells, OS) to remove Pb{sup 2+}, Cd{sup 2+} and Zn{sup 2+} from contaminated water was investigated. Both biogenic sorbents displayed very high sorption capacities for the three metals except for Cd on OS. XRD, SEM and XPS results demonstrated that surface precipitation leading to crystal growth took place during sorption. Calcite OS displayed a remarkably higher sorption capacity to Pb than aragonite RCS, while the opposite was observed for Cd. However, both sorbents displayed similar sorption capacities to Zn. These could be due to the different extent of matching in crystal lattice between the metal bearing precipitate and the substrates. The initial pH of the solution, sorbent's dosage and grain size affected the removal efficiency of the heavy meals significantly, while the organic matter in mollusk shells affected the removal efficiency to a lesser extent. - Highlights: > Mollusk shells display high removal efficiency to heavy metals in contaminated water. > Surface precipitation leading to crystal growth takes place during the sorption. > Crystal structure similarity between precipitates and substrates affects the sorption. > pH, sorbent dosage and grain size of adsorbent affects the removal efficiency. > Organic matter in mollusk shells affects the removal efficiency to a less extent. - Mollusk shells display high sorption ability to heavy metals and crystal structure similarity between precipitates and substrates affects the sorption.

  20. Dissolved Cu, Pb, Zn and Cd in the South China Sea surface waters

    Institute of Scientific and Technical Information of China (English)

    Huo Wenmian; Ji Weidong; Xu Kuncan

    2001-01-01

    A total of 106 surface water samples were collected in the South China Sea during two transects in June and December 1998. The samples were collected with strictly contamination free procedure and trace metals were measured by clean laboratory methods and GFAAS. The mean concentrations for the dissolved fractions are: Cu 0.100 μg/dm3, Pb 0.060 μg/dm3, Zn 0.086 μg/dm3, Cd 0.007 μg/dm3, which is close to the world open ocean's level. The spatial distribution of the trace heavy metals shows higher concentrations in offshore area and lower concentrations in the central in the South China Sea, and the concentrations decrease with the distance from the offshore, which suggests the existence of significant continental shelf input of the trace heavy metals. The correlationship among the elements is better in summer than that in winter. Cu is positively correlated with Cd in both seasons and it is also found for the first time that they are positively correlated with nutrients in the South China Sea surface waters which further indicate the biogeochemical cycle of these elements in the marine environment. The baseline value of Cu, Pb, Zn, Cd in the South China Sea surface waters is obtained through statistical analysis.

  1. Nerita chameleon as Biomonitoring Agent for Pb, Cd, Cu and Zn in Malaysian Intertidal Rocky Shore Environment

    OpenAIRE

    Mohd Fuad Miskon; Noor Azhar Mohd Shazili; Faridah Mohamad; Kamaruzzaman Yunus

    2015-01-01

    Pb, Cd, Cu and Zn in the soft tissue of Nerita chameleon from particular rocky shore sites along the east coast of Peninsular Malaysia were investigated. Samples were measured using ICP-MS with standard configuration. The metal accumulation patterns indicate consistent enrichment of essential metals. Locations with relatively high concentrations of the contaminant metals Pb, Cd and Cu are related to their close proximity to industrial activities and urban sites. Comparison with maximum permis...

  2. 用双硫腙分光光度法同时测定Zn2+、Cd2+和Pb2+%Simultaneous Determination of Zn2+,Cd2+and Pb2+ by Dithizone Spectrophotometric Method

    Institute of Scientific and Technical Information of China (English)

    刘晓红; 李广超

    2001-01-01

    The principle of CPA method for multiple components determination is introduced and applied to simultaneously determining Zn2+,Cd2+ and Pb2+ in mixed solution with dithizone spectrophotometric mehtod.A satisfied result is obtained.%介绍CPA法测定多种组分的原理,并应用该原理,对用双硫腙分光光度法同时测定混合样品中Zn2+、Cd2+和Pb2+的质量浓度进行了研究,取得了较为有意义的结果.

  3. Phytoremediation of Metal (Pb, Ni, Zn, Cd And Cr Contaminated Soils Using Canna Indica

    Directory of Open Access Journals (Sweden)

    V. Subhashini

    2014-12-01

    Full Text Available Heavy metal pollution has become one of the most serious environmental problems today. Remediation of heavy metal polluted soils is one of the significant topics in environmental restoration. As a plant based technology the success of phytoremediation is inherently dependent upon proper plant selection. The present study is an attempt to test the potential of the native species to remove heavy metals from the soil. A pot experiment was conducted to study the metal accumulation capacity of Canna indica L. Canna indica was known as Indian shot belongs to the family Cannaceae. High biomass herb species was selected to restrict the passage of contaminants into the food chain by selecting non-edible, disease resistant and tolerant plants and have very pleasant flowers. Based on the BCF and TF the plant species was used in Pb, Zn and Cr phytoextraction process and Ni and Cd phytostabilization processes. Finally it was concluded that the species was good accumulator of Pb, Ni, Zn, Cd and Cr.

  4. Unmixing of 137Cs, Pb, Zn, and Cd records in lake sediments

    International Nuclear Information System (INIS)

    The inverse Berger-Health model to unmix sedimentary records of particle-associated tracers, originally used for 18O records of particle-associated tracers, originally used for 18O records in deep-sea sediments, is extended to include radioactive materials, environmental pollutants, compaction of sediments, and error analysis. The method is applied to the fallout tracer 137Cs, and to Pb, Zn, and Cd in sediment cores from Lake Michigan. The reconstructued 137Cs input records from northern Lake Michigan. The reconstructed 137Cs input records from northern Lake Michigan are in good agreement with 137Cs fallout data. The unmixed influx records of Pb, Zn, and Cd show excellent agreement with input records reconstructed previously by a frequency domain method, thus supporting the validity of the approach. Assuming that tracer concentrations as well as sedimentation and mixing parameters are known with sufficient accuracy, and that the forward model is correct, the ultimate limitation of this or any other reconstruction method lies in the finite depths of the physical sampling intervals

  5. Spatial distribution of heavy metals (Cu, Pb, Zn, and Cd) in sediments of a coastal wetlands in eastern Fujian, China

    Institute of Scientific and Technical Information of China (English)

    Lili Zhao; Yong Tan; Dongjin He; Weibin You; Haiqing Hu; Wei Hong; Xiaojuan LIAO; Shihong Xiao; Ren Wang; Jinbiao Cai; Xuncheng Fan

    2015-01-01

    We investigated the spatial distribution (horizontal and vertical concentrations) of copper (Cu), lead (Pb), zinc (Zn), and cadmium (Cd) in five wetland types (mudflat, aquaculture wetland, water area, farmland wetland and mangrove) from three areas (Ningde, Fuding, and Xiapu), China. Cu concentrations in five wetland types descended in the order:farm wetland, mudflat, aquaculture, water area and mangrove. Pb concentrations decreased in the order: aquaculture, mangrove, farm wetland, mudflat, and water area. Zn content decreased in the order: farm wetland, water area, aquaculture, mudflat and mangrove, and Cd content decreased as follows: mangrove, aquacul-ture, water area, mudflat, and farm wetland. Comparison of the concentrations of the same heavy metals in different areas showed that the highest Cu (63.75 mg kg-1) and Zn (152.32 mg kg-1) concentrations occurred in Ningde coastal wetlands; Pb (110.58 mg kg-1) and Cd (2.81 mg kg-1) contents were highest in Fuding wetlands, and the average contents of all heavy metals were very low in Xiapu wetlands. Examination of the vertical distribution showed that the Cu content was high in all mudflat layers;Pb and Cd concentrations were highest in aquaculture and mangrove wetlands, respectively, and Zn content was highest in farm wetlands. The spatial distribution of Cu and Zn contents for different areas decreased as follows:Ningde [ Fuding [ Xiapu, for Pb and Cd were most concentrated in Fuding coastal wetlands. Concentrations of Zn and Cu were highly correlated, while Zn and Cu were not significantly correlated with Pb.

  6. Distribution of Cd, Pb, Zn, Mo, and S in juvenile and mature Brassica napus L. var. napus.

    Science.gov (United States)

    Romih, N; Grabner, B; Lakota, M; Ribaric-Lasnik, C

    2012-03-01

    The study was conducted at three locations in the Savinjska region of Slovenia, where soil is contaminated with heavy metals due to the zinc industry (Cinkarna Celje). In Ponikva the soil to a depth of 30 cm contains 0.8 mg kg(-1) Cd, 32.2 mg kg(-1) Pb, and 86 mg Zn kg(-1), in Medlog 1.4 mg kg(-1) Cd, 37.4 mg kg(-1) Pb, and 115 mg kg(-1) Zn and in Skofja vas 10.9 mg kg(-1) Cd, 239.7 mg kg(-1) Pb, and 1356 mg kg(-1) Zn. The pH at the selected sites was between 7.3 and 7.6. In the beginning of September 2006 two hybrids of Brassica napus L. var. napus, PR45 D01 and PR46 W31 suitable for production of biodiesel obtained from Pioneer Seeds Holding GmbH, were sown. After 96 days juvenile and after 277 days mature plants were collected. Parts of plants (root, shoot and seed) were separated and Cd, Pb, Zn, Mo, and S determined by ultra-trace ICP-MS. We compared the uptake of Cd, Pb, Zn, Mo and S in different parts of juvenile and mature plants of the two different hybrids, TF (translocation factor), BAF (bioaccumulation factor), and PP (phytoextraction potential) were calculated. The mature hybrid PR46 W31 had higher shoot/root ratio and higher PP for metals (Cd, Pb, and Zn) and lower PP for the micronutrient (Mo) and macronutrient (S) on the polluted site. The study demonstrated the potential use of oilseed rape on multiply polluted soils for production of 1st and 2nd generation biofuels. The potential restoration of degraded land could also disburden the use of agricultural land. PMID:22567712

  7. Geospatial Mapping of Pb, Cr, Cu, Zn, Cd, and Sb in Urban Soil, Cd. Juarez, Chihuahua, Mexico

    Science.gov (United States)

    Amaya, M. A.; Grimida, S. E.; Elkekli, A. R.; Aldouri, R. K.; Benedict, B. A.; Pingitore, N. E., Jr.

    2015-12-01

    Population-based random stratified sampling of the city of Cd. Juarez, Chihuahua, Mexico provided 500 city blocks for study. We collected soil from the public space (where present) in front of each house on a selected block; equal measured small volumes of these were combined to produce a composite sample for analysis. Such composite samples (1) decrease, by an order of magnitude, laboratory processing and analysis costs, and (2) smooth the data to represent blocks as averages of individual houses. Retention of the unanalyzed samples of the individual houses permits their later analysis should the composites suggest further study of individual houses on an anomalous block. Elemental analysis of 10 mg pressed powders was performed on a Panalytical Epsilon5 EDS-XRF, via 8 secondary targets and 12 USGS and NIST multi-element rock standards. The mean and (range) of concentration for Pb was 43 (13-550) ppm; for Cr, 31 (1.8-76); for Cu, 22 (6-550); for Zn 84 (42-415) ppm; for Cd, 1.9 (0.1-6.2); and for Sb, 5.9 (2.7-29). The old urban core of Cd. Juarez was marked by high levels of Pb, Cr, Cu, and Zn, and, to a smaller degree, of Cd and Sb. This pattern mirrors that of contiguous El Paso, Texas, USA, directly across the narrow Rio Grande. Businesses, industrial facilities, transportation (both railroads and highways), traditional "downtown" shopping, and old residential districts cluster in this urban core. A Pb-Cu-Zn smelter, which operated for more than a century until 1999, is present in the US adjacent to the Rio Grande, about two km away from downtown Cd. Juarez. Thus the city has been subject to both traditional metal sources (e.g., leaded gasoline, highway debris) and smelter emissions. The poplation of Cd. Juarez has exploded in the last few decades to some 1.5 million inhabitants due both to natural growth and in-migration from rural districts for economic opportunity. Most of this growth has been accommodated by radial expansion of the city into the surrounding

  8. Assessment of soil contamination with Cd, Pb and Zn and source identification in the area around the Huludao Zinc Plant

    International Nuclear Information System (INIS)

    The distribution characteristics of heavy metals (cadmium (Cd), lead (Pb) and zinc (Zn)) in the natural soil profiles around the Huludao Zinc Plant (HZP), an old industrial base in Northeast China, were analyzed. The pollutant source was identified using 210Pb isotope technique to evaluate the geochemical characteristics of Pb and the historical production records of HZP. The results indicated: dust precipitation from HZP was the primary source of the pollutants. The average deposition rates of Cd, Pb and Zn were 0.33, 1.75, and 30.97 g/m2 year, respectively at 1 km away after HZP, and 0.0048, 0.035, and 0.20 g/m2 year, respectively at 10 km away after HZP. There is a risk of secondary pollution to the environment as well as the food chain in seriously polluted areas used for cultivation.

  9. Heavy metal (Cu, Zn, Cd and Pb) contamination of vegetables in urban India: A case study in Varanasi

    International Nuclear Information System (INIS)

    The contributions of heavy metals in selected vegetables through atmospheric deposition were quantified in an urban area of India. Deposition rate of Zn was recorded maximum followed by Cu, Cd and Pb. The concentrations of Zn and Cu were highest in Brassica oleracea, Cd in Abelmoschus esculentus and B. oleracea, while Pb was highest in Beta vulgaris. Heavy metal pollution index showed that B. oleracea was maximally contaminated with heavy metals followed by A. esculentus and then B. vulgaris. The results of washing showed that atmospheric deposition has contributed to the increased levels of heavy metals in vegetables. Both Cu and Cd posed health risk to local population via test vegetables consumption, whereas Pb posed the same only through B. oleracea. The study concludes that atmospheric depositions can elevate the levels of heavy metals in vegetables during marketing having potential health hazards to consumers. - Atmospheric depositions can significantly increase the heavy metal concentrations in vegetables during marketing

  10. Valorization of biosorbent obtained from a forestry waste: Competitive adsorption, desorption and transport of Cd, Cu, Ni, Pb and Zn.

    Science.gov (United States)

    Cutillas-Barreiro, Laura; Paradelo, Remigio; Igrexas-Soto, Alba; Núñez-Delgado, Avelino; Fernández-Sanjurjo, María José; Álvarez-Rodriguez, Esperanza; Garrote, Gil; Nóvoa-Muñoz, Juan Carlos; Arias-Estévez, Manuel

    2016-09-01

    Bark from Pinus pinaster is one of the most abundant forestry wastes in Europe, and among the proposed technologies for its reutilization, the removal of heavy metals from wastewater has been gaining increasing attention. In this work, we have studied the performance of pine bark for heavy metal biosorption on competitive systems. Pb, Cu, Ni, Zn and Cd sorption and desorption at equilibrium were studied in batch experiments, whereas transport was studied in column experiments. Batch experiments were performed adding simultaneously different concentrations (0.08-3.15mM) of two or more metals in solution to pine bark samples. Column experiments were performed with 10mM solutions of two metals or a 5mM solution of the five metals. In general, the results under competitive conditions were different to those obtained in monoelemental experiments. The multi-metal batch experiments showed the adsorption sequence Pb≈Cu>Cd>Zn>Ni for lower metal doses, Pb>Cu>Cd>Zn>Ni for intermediate doses, and Pb>Cu>Cd≈Zn≈Ni for high metal doses. Desorption followed the sequence Pbretention, with high capacity to displace Cd, Ni and Zn from adsorption sites on pine bark. The transport experiments produced comparable results to those obtained in the batch experiments, with pine bark retention capacity following the sequence Pb>Cu>Zn>Cd>Ni. The presence of a second metal affected the transport of all the elements studied except Pb, and confirmed the strong influence of Pb and Cu on the retention of the other metals. These results can help to appropriately design decontamination systems using this forestry waste. PMID:27232204

  11. Effect of incubation temperature and wet-dry cycle on the availabilities of Cd, Pb and Zn in soil

    Institute of Scientific and Technical Information of China (English)

    SI Ji-tao; TIAN Bao-guo; WANG Hong-tao

    2006-01-01

    The effect of incubation temperature and wet-dry cycle on the availabilities of Cd, Pb and Zn was studied. Three soils with pH ranging from 3.8 to 7.3, organic carbon (OC) from 0.7% to 2.4%, and clay from 12.3% to 35.6% were selected. Soils were spiked with reagent grade Cd(NO3)2, Pb(NO3)2, and Zn(NO3)2 at concentrations of 30 mg Cd/kg soil, 300 mg Zn/kg soil and 2000 mg Pb/kg soil. The soils were incubated at 35, 60, 105℃, respectively and went through four wet-dry cycles. Metal availability in soils was estimated by soil extraction with 0.1 mol/L Ca(NO3)2. According to this study, the effect of the spiking temperature on the metal availabilities was different among the metals, soils and wet-dry cycles. Mostly, 35℃ was the first recommended spiking temperature for Cd and Pb while no spiking temperature was obviously better than others for Zn. Three wet-dry cycles was recommended regardless of the type of metals and incubation temperature.

  12. Graphite furnace analysis of a series of metals (Cu, Mn, Pb, Zn and Cd) in ox kidney

    International Nuclear Information System (INIS)

    The aim of this study was to create a methodology for animal tissue analysis, with the use of flame atomic absorption spectrophotometry techniques and graphite furnace analysis to determining metal concentrations in ox kidney. The organ of this animal can be considered a great nutritional food, due to the high protein and micronutrient content beyond the ability to absorb and concentrate important metals such as Zn, Fe, Mn and Se. On the other hand, there is a risk when eating this food owing to the capacity to accumulate toxic metals such as Pb and Cd. In accordance with the laboratory analysis, Zn can be analyzed by flame atomic absorption spectrophotometry, but other metals such as Cu, Mn, Pb and Cd, could only be detected by graphite furnace analysis. The results showed that there is more Zn and Cu than other metals. Such metals follows an order reported by the literature (Zn > Cu > Cd > Pb > Mn). The results showed that kidney is actually a rich source of Zn and Cu. The Cd levels in the ox kidney did not exceed the values which cause toxic effects. The adequacy of the results indicates that the proposed methodology can be used for animal tissue analysis.(author)

  13. Sorption processes and XRD analysis of a natural zeolite exchanged with Pb2+, Cd2+ and Zn2+ cations

    International Nuclear Information System (INIS)

    In this study the Pb2+, Cd2+ and Zn2+ adsorption capacity of a natural zeolite was evaluated in batch tests at a constant pH of 5.5 by polluting this mineral with solutions containing increasing concentrations of the three cations to obtain adsorption isotherms. In addition X-ray powder diffraction (XRD) was used to investigate the changes of zeolite structure caused by the exchange with cations of different ionic radius. The zeolite adsorption capacity for the three cations was Zn > Pb > Cd. Moreover a sequential extraction procedure [H2O, 0.05 M Ca(NO3)2 and 0.02 M EDTA] was applied to zeolite samples used in the adsorption experiments to determine the chemical form of the cations bound to the sorbent. Using this approach it was shown that low concentrations of Pb2+, Cd2+ and Zn2+ were present as water-soluble and exchangeable fractions (27% of the Me adsorbed). The XRD pattern of zeolite, analysed according to the Rietveld method, showed that the main mineralogical phase involved in the adsorption process was clinoptilolite. Besides structure information showed that the incorporation of Pb2+, Cd2+ and Zn2+, into the zeolite frameworks changed slightly but appreciably the lattice parameters. XRD analysis also showed the occurrence of some isomorphic substitution phenomena where the Al3+ ions of the clinoptilolite framework were replaced by exchanged Pb2+ cations in the course of the ion exchange reaction. This mechanism was instead less evident in the patterns of the samples doped with Cd2+ and Zn2+ cations

  14. Nerita chameleon as Biomonitoring Agent for Pb, Cd, Cu and Zn in Malaysian Intertidal Rocky Shore Environment

    Directory of Open Access Journals (Sweden)

    Mohd Fuad Miskon

    2015-06-01

    Full Text Available Pb, Cd, Cu and Zn in the soft tissue of Nerita chameleon from particular rocky shore sites along the east coast of Peninsular Malaysia were investigated. Samples were measured using ICP-MS with standard configuration. The metal accumulation patterns indicate consistent enrichment of essential metals. Locations with relatively high concentrations of the contaminant metals Pb, Cd and Cu are related to their close proximity to industrial activities and urban sites. Comparison with maximum permissible limits of toxic metals in food indicated the values were well within safety levels.

  15. Atmospheric Deposition-Carried Pb,Zn,and Cd from a Zinc Smelter and Their Effect on Soil Microorganisms

    Institute of Scientific and Technical Information of China (English)

    YANG Yuan-Gen; JIN Zhi-Sheng; BI Xiang-Yang; LI Fei-Li; SUN Li; LIU Jie; FU Zhi-You

    2009-01-01

    Dust emissions from smelters,as a major contributor to heavy metal contamination in soils,could severely influence soil quality.Downwind surface soils within 1.5 km of a zinc smelter,which was active for 10 years but ceased in 2000,in Magu Town,Guizhou Province,China were selected to examine Pb,Zn,and Cd concentrations and their fractionation along a distance gradient from a zinc smelter,and to study the possible effects of Pb,Zn,and Cd accumulation on soil microorganisms by comparing with a reference soil located at a downwind distance of 10 km from the zinc smelter.Soils within 1.5 km of the zinc smelter accumulated high levels of heavy metals Zn (508 mg kg-1),Pb (95.6 mg kg-1),and Cd (5.98 mg kg-2) with low ratios of Zn/Cd (59.1-115) and Pb/Cd (12.4-23.4).Composite pollution indices (CPIs) of surface soils (2.52-15.2) were 3 to 13 times higher than the reference soils.In metal accumulated soils,exchangeable plus carbonate-bound fractions accounted for more than 10% of the total Zn,Pb,and Cd.The saturation degree of metals (SDM) in soils within 1.5 km of the smelter (averaging 1.25) was six times higher than that of the reference soils (0.209).A smaller soil microbial biomass was found more frequently in metal accumulated soils (85.1-438 μg C g-1) than in reference soils (497 μg C g-1),and a negative correlation (P < 0.01) of soil microbial biomass carbon to organic carbon ratio (Cmic/Corg) with SDM was observed.Microbial consumption of carbon sources was more rapid in contaminated soils than in reference soils,and a shift in the substrate utilization pattern was apparent and was negatively correlated with SDM (R =-0.773,P < 0.01).Consequently,dust deposited Pb,Zn,and Cd in soils from zinc smelting were readily mobilized,and were detrimental to soil quality mainly in respect of microbial biomass.

  16. Measuring reactive pools of Cd, Pb and Zn in coal fly ash from the UK using isotopic dilution assays

    International Nuclear Information System (INIS)

    Highlights: ► Isotope dilution is a useful method to resolve the reactivity of Cd and Pb in ash. ► Only 0.3–3% of the total Pb and Zn and 4–13% of the total Cd in coal ash are labile. ► Fly ash weathering exerts little impact on the lability of Cd, Pb and Zn. ► A 0.05 M EDTA extraction can be used as a simple proxy for isotope dilution assays. - Abstract: Large volumes of coal fly ash are continually being produced and stockpiled around the world and can be a source of environmentally sensitive trace elements. Whilst leaching tests are used for regulatory purposes, these provide little information about the true geochemical behaviour and ‘reactivity’ of trace elements in coal ash because they are poorly selective. Isotope dilution (ID) assays are frequently used in soil geochemistry as a means of measuring the reactive pools of trace metals that are in equilibrium with soil pore waters. This paper examines the applicability of multi-element ID assays in measuring the labile or reactive pool of Cd, Pb and Zn in a range of fresh and weathered fly ash, where pH is generally much more alkaline than in soils. The method generally worked well using 0.0005 M EDTA as a background electrolyte as it provided robust analytical ICP-MS measurements as well as fulfilling the important principle of ID that non-labile metal should not be solubilised. Reactive pools were equivalent to 0.5–3% of the total Pb pool and 4–13% of the total Cd pool. For Zn, where samples had pH < 11.5, the reactive Zn pool varied between 0.3% and 2%; when fresh ash samples with pH > 11.5 were tested, the method failed as the spiked isotope appeared to be sorbed or precipitated. Ash weathering was found to exert little impact on the lability of Cd, Pb and Zn. Isotope dilution results were compared with 0.43 M HNO3 and 0.05 M EDTA extractions, these commonly being used as analogues of the ID assay, and concluded that these can be used as fast, cost-effective and simple proxies for the

  17. Colonisation of a Zn, Cd and Pb hyperaccumulator Thlaspi praecox Wulfen with indigenous arbuscular mycorrhizal fungal mixture induces changes in heavy metal and nutrient uptake.

    Science.gov (United States)

    Vogel-Mikus, Katarina; Pongrac, Paula; Kump, Peter; Necemer, Marijan; Regvar, Marjana

    2006-01-01

    Plants of the Zn, Cd and Pb hyperaccumulator Thlaspi praecox Wulfen (Brassicaceae) inoculated or not with indigenous arbuscular mycorrhizal (AM) fungal mixture were grown in a highly Cd, Zn and Pb contaminated substrate in order to evaluate the functionality of symbiosis and assess the possible impact of AM colonisation on heavy metal uptake and tolerance. The results suggest AM development in the metal hyperaccumulating T. praecox is favoured at elevated nutrient demands, e.g. during the reproductive period. AM colonisation parameters positively correlated with total soil Cd and Pb. Colonised plants showed significantly improved nutrient and a decreased Cd and Zn uptake as revealed by TRXRF, thus confirming the functionality of the symbiosis. Reduced heavy metal uptake, especially at higher soil metal contents, indicates a changed metal tolerance strategy in colonised T. praecox plants. This is to our knowledge the first report on AM colonisation of the Zn, Cd and Pb hyperaccumulator T. praecox in a greenhouse experiment. PMID:15998561

  18. Multi-metal interactions between Cd, Cu, Ni, Pb and Zn in water flea Daphnia magna, a stable isotope experiment

    Energy Technology Data Exchange (ETDEWEB)

    Komjarova, I. [Department of Biology, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium)], E-mail: Irina.Komjarova@ua.ac.be; Blust, R. [Department of Biology, University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium)

    2008-11-11

    Metal interaction effects were investigated in Daphnia magna during a simultaneous exposure to essential (Cu, Ni and Zn) and non-essential (Cd and Pb) metals at environmentally relevant concentrations using a stable isotope technique. The metals were applied in the following concentration ranges: 0.0125-0.2 {mu}M for {sup 106}Cd, 0.025-0.25 {mu}M for {sup 65}Cu and {sup 204}Pb, 0.1-1.25 {mu}M for {sup 62}Ni and {sup 67}Zn. Cadmium and copper exhibited a suppressing effect on the uptake rates of all other metals present in the mixture with the exception to lead at all studied concentrations. The effect was already pronounced at low Cd and Cu concentrations and reached a maximum at the higher concentrations. Nickel and zinc showed weaker interactions with cadmium and between each other, while having no effect on copper and lead uptake. There was a high degree of correlation between Cd, Ni and Zn uptake rates indicating that these metals share in part common uptake or interaction pathways. Moreover, a significant correlation between Zn and Cu uptake processes suggests that more than one mechanism is involved in Zn accumulation since Cu is known to interact with Na uptake sites. The uptake of lead was marked by a high initial rate, but the uptake process reached saturation within 24 h. Cd applied at a concentration of 0.2 {mu}M was the only metal which affected the lead uptake process by stimulation of the Pb uptake. Added to the medium at a concentration of 0.25 {mu}M, lead in turn, increased copper uptake. Current work illustrates that metal interactions are significant and occur at low environmentally realistic concentrations affecting bioavailability of both toxic and essential metals.

  19. Multi-metal interactions between Cd, Cu, Ni, Pb and Zn in water flea Daphnia magna, a stable isotope experiment

    International Nuclear Information System (INIS)

    Metal interaction effects were investigated in Daphnia magna during a simultaneous exposure to essential (Cu, Ni and Zn) and non-essential (Cd and Pb) metals at environmentally relevant concentrations using a stable isotope technique. The metals were applied in the following concentration ranges: 0.0125-0.2 μM for 106Cd, 0.025-0.25 μM for 65Cu and 204Pb, 0.1-1.25 μM for 62Ni and 67Zn. Cadmium and copper exhibited a suppressing effect on the uptake rates of all other metals present in the mixture with the exception to lead at all studied concentrations. The effect was already pronounced at low Cd and Cu concentrations and reached a maximum at the higher concentrations. Nickel and zinc showed weaker interactions with cadmium and between each other, while having no effect on copper and lead uptake. There was a high degree of correlation between Cd, Ni and Zn uptake rates indicating that these metals share in part common uptake or interaction pathways. Moreover, a significant correlation between Zn and Cu uptake processes suggests that more than one mechanism is involved in Zn accumulation since Cu is known to interact with Na uptake sites. The uptake of lead was marked by a high initial rate, but the uptake process reached saturation within 24 h. Cd applied at a concentration of 0.2 μM was the only metal which affected the lead uptake process by stimulation of the Pb uptake. Added to the medium at a concentration of 0.25 μM, lead in turn, increased copper uptake. Current work illustrates that metal interactions are significant and occur at low environmentally realistic concentrations affecting bioavailability of both toxic and essential metals

  20. Dicarboxylated ethynylarenes as buffer-dependent chemosensors for Cd(II), Pb(II) and Zn(II)

    OpenAIRE

    Fletcher, James T.; Bruck, Brent S.; Deever, Douglas E.

    2013-01-01

    Two dicarboxylated ethynylarenes were prepared efficiently from condensation of 1,3-bis(3-aminoph enylethynyl)benzene with two equivalents of either succinic anhydride or glutaric anhydride. These compounds behave as fluorescent chemosensors selective for Cd(II), Pb(II) and Zn(II) cations under buffered aqueous conditions, with analyte binding observed as bathochromically shifted, intensified fluorescence. It was noteworthy that the fluorescence responses varied significantly with buffer iden...

  1. Application of atomic absorption spectrophotometry to determine Cd, Cu, Pb, Zn,...in vegetable samples in Dalat

    International Nuclear Information System (INIS)

    Nowadays atomic absorption spectrometry has become valuable method for trace element analysis because high specificity; low detection litmus, easy to use; easy sample preparation, low investment and running costs... atomic absorption spectrometry is generally accepted as one the most suitable method for single - element analysis of trace elements in various kinds of materiel. In 2003, we applied flame - atomic absorption spectrometry for analyzing Ca, Cd, Cu, Pb, Zn...in vegetables and their extracted juices were collected form 11 locations of Dalat, including two kinds of vegetables (goods and safety) in both the summer and winter. Average concentration of Ca = 240 mg/kg wet, Cd = 0.035 mg/kg wet, Cu = 0.67 mg/kg wet, Mg = 131 mg/kg wet, Fe = 8.1/kg wet, Mn = 3.1/kg wet, Na = 3266 mg/kg wet, Pb = 0.345 mg/kg wet and Zn = 3.3 mg wet. In their extracted juices: Ca = 89 mg/kg wet, Cd = 0.008 mg/kg wet, Cu = 0.19 mg/kg wet, Mg = 43 mg/kg wet, Fe = 2.3 mg/kg wet, Mn = 0.61 mg/kg wet, Na = 971 mg/kg wet, Pb = 0.107 mg/kg wet and Zn = 0.65 mg/kg wet. (author)

  2. Eisenia fetida avoidance behavior as a tool for assessing the efficiency of remediation of Pb, Zn and Cd polluted soil

    Energy Technology Data Exchange (ETDEWEB)

    Udovic, Metka [Centre for Soil and Environmental Science, Department of Agronomy, Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, Sl-1000 Ljubljana (Slovenia); Lestan, Domen, E-mail: domen.lestan@bf.uni-lj.s [Centre for Soil and Environmental Science, Department of Agronomy, Biotechnical Faculty, University of Ljubljana, Jamnikarjeva 101, Sl-1000 Ljubljana (Slovenia)

    2010-08-15

    Remediation by means of soil leaching with ethylenediaminetetraacetic acid (EDTA) is capable of extracting the most labile soil fractions, leaving the residual metals in biologically non-available forms. We evaluated the feasibility of the standardized earthworm (Eisenia fetida) avoidance test for assessing the efficiency of soil remediation of Pb, Zn and Cd polluted soil. Chemical extraction tests (six-step sequential extraction, toxicity characteristic leaching procedure, physiologically based extraction test, diethylenediaminepentaacetic acid extraction) indicated that the mobility, oral bioaccessibility and phytoavailability of Pb, Zn and Cd were consistently reduced. However, the avoidance test showed no significant avoidance of polluted soil in favor of that which had been remediated. Pb, Zn and Cd accumulation in E. fetida mirrored the decreasing pattern of metal potential bioavailability gained by leaching the soil with increasing EDTA concentrations. The calculated bioaccumulation factors indicated the possibility of underestimating the metal bioavailability in soil using chemical extraction tests. - Tests with indicator organisms should be used for a more meaningful and holistic assessment of metal biological availability in polluted and remediated soil.

  3. Geochemical and mineralogical evolution of the Zn-Cd-Pb bearing tailings from the Saint-Salvy mine, France

    Science.gov (United States)

    Munoz, M.; Courjault-Radé, P.; Castet, S.; Martin, F.; Tollon, F.

    2003-05-01

    4 million tonnes of waste generated by the treatment plant of the Saint-Salvy Zn mine have been dumped in a storage dam. Sulphides (3.5%) and Mn-siderite (20%) oxydize and dissolve. Drainage water exports most of SO4 and Mn released. According to geochemical modelling taking into account slightly acidic pH and slightly reducing conditions within the tailings, ferrihydrite precipitates in situ inducing partial immobilization of Fe, and partial retention of Zn, Pb and Cd. Time required for site inertization is estimated around a century.

  4. Characterization of bacteria in the rhizosphere soils of Polygonum pubescens and their potential in promoting growth and Cd, Pb, Zn uptake by Brassica napus.

    Science.gov (United States)

    Jing, Yuan Xiao; Yan, Jun Lan; He, Huai Dong; Yang, Dan Jing; Xiao, Li; Zhong, Ting; Yuan, Ming; Cai, Xin De; Li, Shu Bin

    2014-01-01

    Microbe-enhanced phytoremediation has been considered as a promising measure for the remediation of metal-contaminated soils. In this study, two bacterial strains JYX7 and JYX10 were isolated from rhizosphere soils of Polygonum pubescens grown in metal-polluted soil and identified as of Enterobacter sp. and Klebsiella sp. based on 16S rDNA sequences, respectively. JYX7 and JYX10 showed high Cd, Pb and Zn tolerance and increased water-soluble Cd, Pb and Zn concentrations in culture solution and metal-added soils. Two isolates produced plant growth-promoting substances such as indole acetic acid, siderophore, 1-aminocyclopropane-1-carboxylic deaminase, and solubilized inorganic phosphate. Based upon their ability in metal tolerance and solubilization, two isolates were further studied for their effects on growth and accumulation of Cd, Pb, and Zn in Brassica napus (rape) by pot experiments. Rapes inoculated with JYX7 and JYX10 had significantly higher dry weights, concentrations and uptakes of Cd, Pb, Zn in both above-ground and root tissues than those without inoculation grown in soils amended with Cd (25 mg kg(-1)), Pb (200 mg kg(-1)) or Zn (200 mg kg(-1)). The present results demonstrated that JYX7 and JYX10 are valuable microorganism, which can improve the efficiency of phytoremediation in soils polluted by Cd, Pb, and Zn. PMID:24912234

  5. Colonisation of a Zn, Cd and Pb hyperaccumulator Thlaspi praecox Wulfen with indigenous arbuscular mycorrhizal fungal mixture induces changes in heavy metal and nutrient uptake

    Energy Technology Data Exchange (ETDEWEB)

    Vogel-Mikus, Katarina [Department of Biology, Biotechnical Faculty, University of Ljubljana, Vecna pot 111, SI-1000 Ljubljana (Slovenia); Pongrac, Paula [Department of Biology, Biotechnical Faculty, University of Ljubljana, Vecna pot 111, SI-1000 Ljubljana (Slovenia); Kump, Peter [Jozef Stefan Institute, Jamova 39, SI-1000 Ljubljana (Slovenia); Necemer, Marijan [Jozef Stefan Institute, Jamova 39, SI-1000 Ljubljana (Slovenia); Regvar, Marjana [Department of Biology, Biotechnical Faculty, University of Ljubljana, Vecna pot 111, SI-1000 Ljubljana (Slovenia)]. E-mail: marjana.regvar@bf.uni-lj.si

    2006-01-15

    Plants of the Zn, Cd and Pb hyperaccumulator Thlaspi praecox Wulfen (Brassicaceae) inoculated or not with indigenous arbuscular mycorrhizal (AM) fungal mixture were grown in a highly Cd, Zn and Pb contaminated substrate in order to evaluate the functionality of symbiosis and assess the possible impact of AM colonisation on heavy metal uptake and tolerance. The results suggest AM development in the metal hyperaccumulating T. praecox is favoured at elevated nutrient demands, e.g. during the reproductive period. AM colonisation parameters positively correlated with total soil Cd and Pb. Colonised plants showed significantly improved nutrient and a decreased Cd and Zn uptake as revealed by TRXRF, thus confirming the functionality of the symbiosis. Reduced heavy metal uptake, especially at higher soil metal contents, indicates a changed metal tolerance strategy in colonised T. praecox plants. This is to our knowledge the first report on AM colonisation of the Zn, Cd and Pb hyperaccumulator T. praecox in a greenhouse experiment. - Colonisation of a Zn, Cd and Pb hyperaccumulator Thlaspi praecox with arbuscular mycorrhizal fungi resulted in improved nutrient and reduced Cd and Zn uptake.

  6. A comparative study of the most effective amendment for Pb, Zn and Cd immobilization in contaminated soils.

    Science.gov (United States)

    Szrek, Dominik; Bajda, Tomasz; Manecki, Maciej

    2011-01-01

    The problem of an extensive contamination of soils with metals can be resolved using an in situ chemical immobilization technology. Five substances (natural zeolite, bog iron ore, "Polifoska 15" fertilizer, triple superphosphate, diammonium phosphate) were tested to determine their efficiency to immobilize Zn, Pb and Cd in smelter-contaminated soil in the Upper Silesia region. Soil samples were collected at three sites located in the vincity of a Pb-Zn smelter and a sludge landfill near the town of Bukowno. Effective reduction of leachable and fitoavailable Zn, Pb and Cd concentrations in soil was observed after addition of diammonium phosphate, "Polifoska 15" fertilizer and bog iron ore amendments. Additional test proved that immobilization effect gained by these amendments sustains at low-temperature conditions. It was noticed that phosphate addition resulted in lowering pH and mobilization of As(V) in soils. Good immobilization effectiveness and lack of major adverse effects of bog iron application suggest that this is the method of choice. PMID:21961559

  7. Genotypic variations in the accumulation of Cd, Cu, Pb and Zn exhibited by six commonly grown vegetables

    International Nuclear Information System (INIS)

    Metal contaminants in garden and allotment soils could possibly affect human health through a variety of pathways. This study focused on the potential pathway of consumption of vegetables grown on contaminated soil. Five cultivars each of six common vegetables were grown in a control and in a soil spiked with Cd, Cu, Pb and Zn. Highly significant differences in metal content were evident between cultivars of a number of vegetables for several of the contaminants. Carrot and pea cultivars exhibited significant differences in accumulated concentrations of Cd and Cu with carrot cultivars also exhibiting significant differences in Zn. Distinctive differences were also identified when comparing one vegetable to another, legumes (Leguminosae) tending to be low accumulators, root vegetables (Umbelliferae and Liliaceae) tending to be moderate accumulators and leafy vegetables (Compositae and Chenopodiaceae) being high accumulators. - Genotypic differences between cultivars of vegetable species can be important in determining the extent of accumulation of metals from contaminated soil

  8. Fifty-year sedimentary record of heavy metal pollution (Cd, Zn, Cu, Pb) in the Lot River reservoirs (France)

    International Nuclear Information System (INIS)

    The Lot-Garonne fluvial system is known for its historic heavy metal pollution resulting from mining and smelting activities since the late 19th century. Here, we report 137Cs activities and heavy metal (Cd, Zn, Cu, Pb and V) concentration-depth profiles from sediment cores retrieved in 2001 from three reservoirs in the Lot River. High mean sedimentation rates of 2.4-2.8 cm a-1 are indicated by 137Cs dating. The reservoir sediments have recorded the heavy metal deposition and thus allow establishing a connection between the temporal evolution of the heavy metal pollution and historical changes in smelting and waste-treatment proceedings. Based on heavy metal concentrations in sediments upstream of the anthropogenic inputs and bottom-sediments of the furthest downstream core (interpreted as old soil or riverbed), concentrations of ∼17, ∼82, ∼0.33 and ∼28 mg kg-1 for Cu, Zn, Cd and Pb, respectively, are proposed as natural background values for the Lot fluvial system. The geoaccumulation index (Igeo [Mueller, G., 1979. Schwermetalle in den Sedimenten des Rheins-Veraenderungen seit. Umschav 79, 133-149.]) revealed that the Lot River sediments must be considered as 'severely polluted' in Cd and Zn. Moreover, despite remediation efforts undertaken in the former smelting site, the Lot River is still ''severely'' (Igeo ∼ 4) and ''moderately to severely'' (Igeo > 2) impacted by Cd and Zn inputs, respectively. - Capsule: Reservoir sediments provide fine-scale information on the historical record of metal pollution in a watershed

  9. Experimental analysis of the simultaneous uptake of the heavy metals Cd, Hg, Pb, Cu, Zn, Se in the sporophore of mushrooms. Versuche ueber die simultane Aufnahme der Schwermetalle Cd, Hg, Pb, Cu, Zn und Se in Pilzfruchtkoerper

    Energy Technology Data Exchange (ETDEWEB)

    Suehs, K.

    With mushrooms of the species Agaricus bisporus and Boletus badius the simultaneous uptake of the heavy metals Cd, Hg, Pb, Cu, Zn, and Se from soil to the sporophore was studied. To avoid misleadingly overrated enrichmentfactors when comparing the heavy metal contents of dried mushrooms and soils, a so-called transfer factor TF[sub v] which is related to the volume is put to discussion here, this factor takes account of the relatively small amount of dry matter in mushrooms and of the different composition (that means specific weight) of the soils in question. With help of these transfer factors the conclusion is derived, that essential elements show a better enrichment behaviour than biologically superfluous heavy metals, at least this is true with the insignificantly contaminated soils we investigated. With Cd as an example of a ''superfluous'' element it is shown that there is a strict proportionality of Cd concentrations in the mushrooms and the corresponding soils, thus producing a constant transfer factor. Apart from this the uptake of copper into the mushrooms is promoted (growth of the transfer factor) by a larger Cd supply, whereas the other elements under investigation (even the classical antagonist Zn) are not significantly affected. Furthermore there is evidence that with increasing heavy metal concentration (Cd) first the fructification of the thallus is supported and moreover, that increasing age of this primary fungus corresponds with an increase of heavy metals in the mushrooms. (orig.)

  10. Ecophysiological and seasonal variations in Cd, Pb, Zn, and Ni concentrations in the leaves of urban deciduous trees in Istanbul

    International Nuclear Information System (INIS)

    The concentrations of Cd, Pb, Zn and Ni were measured in the leaves of 7 species of deciduous trees, from the urban sites of Istanbul, in both the Spring and Autumn seasons. We detected some differences in the heavy metal concentrations of the control and urban site samples of identical species. Highest concentrations of Cd were detected in Populus, Pb in Aesculus and Robinia, Zn in Populus, and Ni in Robinia and Fraxinus. Lowest chlorophyll content and highest peroxidase (POD) activity was found in the urban site samples of Acer. We have found a positive correlation between the increase in the POD activity and the Pb concentration in Populus. Generally, the tree species investigated in this study, are considered to have different tolerance levels to heavy metal pollution. The data obtained show that the chlorophyll content and the POD activity may be used as heavy metal stress biomarkers in the urban trees. - Ecophysiological changes in the urban trees may be used as heavy metal stress biomarkers

  11. Influence of operating conditions on the removal of Cu, Zn, Cd and Pb ions from wastewater by adsorption

    International Nuclear Information System (INIS)

    Nile Rose Plant was used to study adsorption of several cations (Cu2+, Zn2+, Cd2+ and Pb2+) from wastewater within various experimental conditions. The dried leaves of Nile Rose Plant were used at different adsorbent/ metal ion ratios. The influence of p H, contact time, metal concentration, and adsorbent loading weight on the removal process was investigated. Batch adsorption studies were carried out at room temperature. The adsorption efficiencies were found to be p H dependent, increasing by increasing the ph in the range from 2.5 to 8.5 except for Pb. The equilibrium time was attained within 60 to 90 min. and the maximum removal percentage was achieved at an adsorbent loading weight of 1.5 g/50 m L mixed ions solution. Isothermal studies showed that the data were best fitted to the temkin isotherm model. The removal order was found to be Pb2+ Zn2+> Cu2+> Cd2=. The surface IR-characterization of Nile rose plant showed the presence of many functional groups capable of binding to the metal cations

  12. Risk assessment for Cd, Cu, Pb and Zn in urban soils: Chemical availability as the central concept

    International Nuclear Information System (INIS)

    To assess the geochemical reactivity and oral bioaccessibility of Cd, Cu, Pb and Zn in urban soils from the Porto area, four extractions were performed including Aqua Regia (AR; pseudototal), 0.43 M HNO3 (reactive), 0.01 M CaCl2 (available), and 0.4 M glycine at pH = 1.5, SBET method (oral bioaccessible pool). Oral bioaccessibility in urban soils was higher than in samples from rural, industrial and mining areas which is most likely related to sources of metals and parent materials of corresponding soils. The availability and reactivity were described well by non-linear Freundlich-type equations when considering differences in soil properties. The resulting empirical models are able to predict availability and reactivity and can be used to improve the accuracy of risk assessment. Furthermore, a close 1:1 relationship exists between results from the 0.43 M HNO3 method and the SBET method which substantially facilitates risk assessment procedures and reduces analytical costs. -- Highlights: ► Availability of PTEs in urban soils is described well by non-linear Freundlich-type equations. ► A 1:1 relationship was obtained between the 0.43 M HNO3 method and the SBET method. ► A single soil extraction indicates reactivity and bioaccessibility of metals in soils. ► The reactive pool is suitable to assess risks of Cd, Cu, Pb and Zn in urban soils. -- A single analysis of the reactive pool by dilute nitric acid is suitable to assess risks of Cd, Cu, Pb and Zn in urban soils related to leaching to (ground)water and exposure to human beings (bioaccessibility)

  13. Monitoring air pollution at Mohammedia (Morocco): Pb, Cd and Zn in the blood of pigeons (Columba livia).

    Science.gov (United States)

    Kouddane, N; Mouhir, L; Fekhaoui, M; Elabidi, A; Benaakame, R

    2016-05-01

    The concentrations of Pb, Cd and Zn were investigated in the blood of pigeons (Columba livia) in order to assess the degree of pollution by heavy metal. For this, wild city pigeons were caught at four different locations in Mohammedia classified according to their industrial activity and road traffic density. Significant difference in heavy metal concentrations were observed between sites studied, the highest lead and cadmium levels were found in industrial area and center town, while the highest zinc level was found in the less contaminated area. These results indicate that the industrial activities and the road traffic are the most important source of pollution. PMID:26903169

  14. Organic acid enhanced soil risk element (Cd, Pb and Zn) leaching and secondary bioconcentration in water lettuce (Pistia stratiotes L.) in the rhizofiltration process.

    Science.gov (United States)

    Veseý, Tomás; Tlustos, Pavel; Száková, Jirina

    2012-04-01

    The use of natural chelates to enhance risk element mobility combined with rhizofiltration by free floating macrophytes have not been thoroughly studied in recent years. The aim of this study was to investigate the efficiency of organic acids in soil by conducting flushing experiments to enhance the mobility of Cd, Pb, and Zn from soil to solution. In addition, the bioaccumulation of Cd, Pb, and Zn, in water lettuce (Pistia stratiotes L.) will be studied as they affect the biomass in the rhizofiltration process. The results revealed that citric and tartaric acids mobilised the highest amount of all risk elements. In comparison to control, citric acid mobilised 71%, 181%, and 112% of Cd, Pb, and Zn while tartaric acid mobilised 70%, 155%, and 135% of Cd, Pb, and Zn respectively. The bioconcentration factor was approximately 2-5 times higher for juvenile plants than mature plants for all treatments as well as for both parts (leaves and roots). The risk element translocation into aerial parts decreased with increased time. Juvenile and mature plants proved a high accumulation potential and a 3 week growth period was observed as a sufficient time period to remove more than 80% of Cd, Pb, and Zn. PMID:22567715

  15. Activated carbon and biochar from agricultural by-products in the adorption of Cd, Pb and Zn under laboratory conditions

    Science.gov (United States)

    Coscione, Aline; Zini, Barbara

    2015-04-01

    The immobilization of inorganic contaminants by using biochar in soils has played an increasingly important role and it is seen as an attractive alternative for the remediation of heavy metals. Although, the production of activated carbon (CA) from agricultural by-products has received special attention, the activation of the the organic source has been studied in order to increase its porposity, surface area and chemical polarity, resulting in higher adsorption of metals. Therefore, this study aimed to evaluate the effectiveness of BC and CA samples, obtained from a eucalyptus husks and cane sugar bagasse after activation with 20% phosphoric acid and pyrolyzed at 450oC in the retention of Zn, Cd and Pb using contaminated individual solutions. The experiment was performed using samples of activated carbon of eucalyptus husk (CCA), eucalyptus husk biochar (BC), activated carbon of sugar cane bagasse (CBA) and sugar cane bagasse biochar (BB), treated with Zn, Cd (range of tested solution from 0.1 up to 12 mmol L-1) and Pb (from 0.1 up 50 mmol L-1) and the adjustemento of Langmuir adsorption isotherms. Samples obtained from bagasse presented higher adsoprtion of the metals tested then eucalyptus. Also the activation process had not the expected effect on either eucalyptus and bagasse samples The maxmum adsorption capacyty of samples were as follws, in mmol g-1: for Cd - 0.36 for BC; 0.32 for CCA; 0.40 for BB; 0.31 for CBA. For Zn- 0.14 for BC; no adsorbed by CCA; 0.35 5 for BB; 0.06 for CBA. For Pb - 1.24 for BC; 0.40 for CCA; 0,45 for BB; 0,03 for CBA. However, it was also observed that due to the activation with phosphoric acid, the pH of the activated carbon (CCA and CBA) were 2.4 and 2.5 in comparison with the biochars not activated (BC and BB) 9.7 and 7.0 respectively. Thus, it is yet not possible to state if the calculate capacity is due exclusively to the complexation of chemical groups in the surface of samples or to which extent there is a contribution of

  16. Utilization of biochar and activated carbon to reduce Cd, Pb and Zn phytoavailability and phytotoxicity for plants.

    Science.gov (United States)

    Břendová, Kateřina; Zemanová, Veronika; Pavlíková, Daniela; Tlustoš, Pavel

    2016-10-01

    In the present study, the content of risk elements and content of free amino acids were studied in spinach (Spinacia oleracea L.) and mustard (Sinapis alba L.) subsequently grown on uncontaminated and contaminated soils (5 mg Cd/kg, 1000 mg Pb/kg and 400 mg Zn/kg) with the addition of activated carbon (from coconut shells) or biochar (derived from local wood residues planted for phytoextaction) in different seasons (spring, summer and autumn). The results showed that activated carbon and biochar increased biomass production on contaminated site. Application of amendments decreased Cd and Zn uptake by spinach plants. Mustard significantly increased Pb accumulation in the biomass as well in subsequently grown autumn spinach. Glutamic acid and glutamine were major free amino acids in leaves of all plants (15-34% and 3-45%) from total content. Application of activated carbon and biochar increased content of glutamic acid in all plants on uncontaminated and contaminated soils. Activated carbon and biochar treatments also induced an increase of aspartic acid in spinach plants. Biochar produced from biomass originated from phytoextraction technologies promoted higher spinach biomass yield comparing unamended control and showed a tendency to reduce accumulation of cadmium and zinc and thus it is promising soil amendment. PMID:27544477

  17. Survey of Heavy Metals (Cd, Pb, Hg, Zn and Cu Contamination in Sediment of Three Sites Anzali Wetland

    Directory of Open Access Journals (Sweden)

    M khosravi

    2011-06-01

    Full Text Available Background and Objectives:Anzali Wetland is one of the most important aquatic ecosystems of Iran which is located in south-west of the Caspian sea. This Wetland provides a suitable and non-market price habitat for valuable fish and aquatic animals which have an important role in the life cycle of this ecosystem. This study reports the results of some heavy metals contamination monitoring in superficial water of the Anzali Wetland, Iran.Materials and Methods: The samples were collected from three sites (east, center and west of Anzali Wetland, in each site three stations existed and each sample replicated three times.Results: The results showed high heavy metal levels in eastern site of wetland, where there were high levels of contamination. The mean of heavy metals concentration in sediment from Anzali Wetland were in order as Cd 157.023, Pb 3.646 and Hg 300.692 ng /g dried weight, Zn 186.953 and Cu 44.452 mg /g dried weight in eastern site. The concentration levels of heavy metals in three sites were in order as follows: Zn > Cu > Hg > Cd > Pb. Conclusion: Concentrations of heavy metals in eastern zone reflected metal loadings from anthropogenic sources located at and in the vicinity of the sampling sites.

  18. Bioaccumulation of Cd, Pb and Zn in the edible and inedible tissues of three sturgeon species in the Iranian coastline of the Caspian Sea.

    Science.gov (United States)

    Mashroofeh, Abdulreza; Bakhtiari, Alireza Riyahi; Pourkazemi, Mohammad; Rasouli, Sana

    2013-01-01

    The accumulations of Cd, Pb and Zn were determined in edible and inedible tissues of Persian sturgeon (Acipenser persicus; n=27), stellate sturgeon (Acipenser stellatus; n=5) and beluga (Huso huso; n=4) collected from coastal waters of the South Caspian Sea from March to April 2011. Concentrations of metals evaluated in the caviar, muscle, liver, kidney, gills, ovary and heart of the three species of sturgeons have been assessed using the flame and graphite furnace atomic absorption spectrophotometer. Concentrations of Zn, Pb and Cd in the edible and inedible tissues were apparently different among the three species of sturgeons. Especially, beluga heart showed the highest concentrations of Zn and Pb and Cd in Persian sturgeon liver. The analyzed metals were found in the caviar and muscle samples of Persian sturgeon and likewise muscle samples two other sturgeon species at mean concentrations under the permissible limits proposed by MAFF (2000). PMID:22990022

  19. Contents of metals Pb, Cd, Zn and Cu in Agricultural Soils of Zagreb and Its Surroundings

    Directory of Open Access Journals (Sweden)

    Marija Romić

    1998-09-01

    The highest average cadmium content of 0.93 mg/kg Cd per designated regions was recorded in the youngest river valley along the Sava. Anomalous values were also encountered in the youngest valley along the Sava watercourse, where the average zinc content amounted to 87.08 mg/kg Zn, which are classified as highly contaminated soils. Higher copper values were determined in the hilly area of Mt. Medvednica and Pleistocene of sloping terrains, which seems to be related to the manner of land use (vineyards, gardens at private holdings.

  20. Can the shell of the green-lipped mussel Perna viridis from the west coast of Peninsular Malaysia be a potential biomonitoring material for Cd, Pb and Zn?

    Science.gov (United States)

    Yap, C. K.; Ismail, A.; Tan, S. G.; Abdul Rahim, I.

    2003-07-01

    The distributions of Cd, Pb and Zn in the total soft tissues and total shells of the green-lipped mussel Perna viridis were studied in field collected samples as well as from laboratory experimental samples. The results showed that Cd, Pb and Zn were readily accumulated in the whole shells. In mussels sampled from 12 locations along the west coast of Peninsular Malaysia, the ratios of the shell metals to the soft tissue metals were different at each sampling site. Nevertheless, the Cd and Pb levels in the shells were always higher than those in the soft tissues, while the Zn level was higher in the soft tissues than in the shells. In comparison with soft tissues, the degrees of variability for Pb and Cd concentrations in the shells were lower. The lower degrees of variability and significant ( Pshells support the use of the mussel shell as a suitable biomonitoring material for the two metals rather than the soft tissue since this indicated that there is more precision (lower CV) in the determination of metal concentrations in the shell than in the soft tissue. Experimental work showed that the pattern of depuration in the shell was not similar to that of the soft tissue although their patterns of accumulation were similar. This indicated that the depuration of heavy metals in the shell was not affected by the physiological conditions of the mussels. Although Zn could be regulated by the soft tissue, the incorporated Cd, Pb and Zn remained in the shell matrices. The present results support the use of the total shell of P. viridis as a potential biomonitoring material for long-term contamination of Cd, Pb and Zn.

  1. Characterization of endophytic Rahnella sp. JN6 from Polygonum pubescens and its potential in promoting growth and Cd, Pb, Zn uptake by Brassica napus.

    Science.gov (United States)

    He, Huaidong; Ye, Zhihong; Yang, Danjing; Yan, Junlan; Xiao, Li; Zhong, Ting; Yuan, Ming; Cai, Xinde; Fang, Zhanqiang; Jing, Yuanxiao

    2013-02-01

    Microbe-assisted phytoremediation has been considered as a promising measure for the remediation of heavy metal-polluted soils. In this study, a metal-tolerance and plant growth-promoting endophytic bacterium JN6 was firstly isolated from roots of Mn-hyperaccumulator Polygonum pubescens grown in metal-contaminated soil and identified as Rahnella sp. based on 16S rDNA gene sequence analysis. Strain JN6 showed very high Cd, Pb and Zn tolerance and effectively solubilized CdCO(3), PbCO(3) and Zn(3)(PO(4))(2) in culture solution. The isolate produced plant growth-promoting substances such as indole-3-acetic acid, siderophore, 1-aminocyclopropane-1-carboxylic deaminase, and also solubilized inorganic phosphate. Based upon its ability in metal tolerance and solubilization, the isolate JN6 was further studied for its effects on the growth and accumulation of Cd, Pb and Zn in Brassica napus (rape) by pot experiments. Rape plants inoculated with the isolate JN6 had significantly higher dry weights, concentrations and uptake of Cd, Pb and Zn in both above-ground and root tissues than those without inoculation grown in soils amended with Cd (25 mg kg(-1)), Pb (200 mg kg(-1)) or Zn (200 mg kg(-1)). The isolate also showed a high level of colonization in tissue interior of rapes. The present results demonstrated that Rahnella sp. JN6 is a valuable microorganism, which can cost-effectively improve the efficiency of phytoremediation in soils contaminated by Cd, Pb and Zn. PMID:23177711

  2. The relationships between heavy metal (Cd, Cr, Cu, Fe, Pb, Zn) levels and the size of six Mediterranean fish species

    International Nuclear Information System (INIS)

    Significant relationships between metal concentrations and fish size were negative. - Heavy metal (Cd, Cr, Cu, Fe, Pb, Zn) concentrations in the muscle, gill and liver of six fish species (Sparus auratus, Atherina hepsetus, Mugil cephalus, Trigla cuculus, Sardina pilchardus and Scomberesox saurus) from the northeast Mediterranean Sea were measured and the relationships between fish size (length and weight) and metal concentrations in the tissues were investigated by linear regression analysis. Metal concentrations (as μg/g d.w.) were highest in the liver, except for iron in the gill of Scomberesox saurus and lowest in the muscle of all the fish species. Highest concentrations of Cd (4.50), Cr (17.1) and Pb (41.2) were measured in liver tissues of T. cuculus, Sardina pilchardus and A. hepsetus, respectively. The liver of M. cephalus showed strikingly high Cu concentrations (202.8). The gill of Scomberesox saurus was the only tissue that showed highest (885.5) iron concentrations. Results of linear regression analysis showed that, except in a few cases, significant relationships between metal concentrations and fish size were negative. Highly significant (P<0.001) negative relationships were found between fish length and Cr concentrations in the liver of A. hepsetus and M. cephalus, and Cr concentrations in the gill of T. cuculus. Cr and Pb concentrations in the liver and Cu concentrations in all the tissues of Scomberesox saurus also showed very significant (P<0.001) negative relationships. Negative relationships found here were discussed

  3. Effect of Na, Ca and pH on simultaneous uptake of Cd, Cu, Ni, Pb, and Zn in the water flea Daphnia magna measured using stable isotopes

    International Nuclear Information System (INIS)

    The present study investigates the effects of Na+, Ca2+ and pH on the kinetics of Cd, Cu, Ni, Pb, and Zn uptake in Daphnia magna at low exposure concentrations measured using a stable isotope technique. Using experimental data the uptake rate constants were calculated for each metal individually on the basis of total metal concentrations. The copper uptake was not significantly affected by variations in chemical composition of the test medium. Calcium had a suppressing effect on the uptake of Cd, Ni, Pb and Zn. Specifically, Cd and Ni uptake rate constants decreased with increases in calcium concentrations from 0.1 to 2.5 mM. The uptake of Zn and Pb was significantly suppressed only at 2.5 mM Ca. The effect of sodium was less clear. There was no effect of varying sodium concentrations on the Ni uptake rate constants. Cd and Pb showed an increase in uptake rate constants at elevated sodium concentrations (2-8 mM Na+ for Cd and 8 mM Na+ for Pb). A bell-shaped response on increasing Na+ concentrations was observed for Zn with a maximum value of uptake rate constant at the middle value (2 mM Na+). Variation in pH of the medium affected Cd, Ni and Zn uptake processes. When Daphnia were exposed to acidic conditions (pH 6), the Cd and Ni uptake rate constants were the highest, while similarly low values were observed at neutral and basic conditions. In contrast, the uptake rates of Zn were linearly increasing with increasing pH of the medium.

  4. The solid-solution partitioning of heavy metals (Cu, Zn, Cd, Pb) in upland soils of England and Wales

    International Nuclear Information System (INIS)

    Solid-solution distributions of heavy metals can be described quantitatively by multiple regression and mechanistic modelling. - Ninety-eight surface soils were sampled from the uplands of England and Wales, and analysed for loss-on-ignition (LOI), and total and dissolved base cations, Al, Fe, and trace heavy metals (Cu, Zn, Cd, Pb). The samples covered wide ranges of pH (3.4-8.3) and LOI (9-98%). Soil metal contents measured by extraction with 0.43 mol l-1 HNO3 and 0.1 mol l-1 EDTA were very similar, and generally lower than values obtained by extraction with a mixture of concentrated nitric and perchloric acids. Total heavy metal concentrations in soil solution depend positively upon soil metal content and [DOC], and negatively upon pH and LOI, values of r2 ranging from 0.39 (Cu) to 0.81 (Pb). Stronger correlations (r2=0.76-0.95) were obtained by multiple regression analysis involving free metal ion (Cu2+, Zn2+, Cd2+, Pb2+) concentrations calculated with the equilibrium speciation model WHAM/Model VI. The free metal ion concentrations depend positively upon MHNO3 and negatively upon pH and LOI. The data were also analysed by using WHAM/Model VI to describe solid-solution interactions as well as solution speciation; this involved calibrating each soil sample by adjusting the content of 'active' humic matter to match the observed soil pH. The calibrated model provided fair predictions of total heavy metal concentrations in soil solution, and predicted free metal ion concentrations were in reasonable agreement with the values obtained from solution-only speciation calculations

  5. Effect of biochar on the extractability of heavy metals (Cd, Cu, Pb, and Zn) and enzyme activity in soil.

    Science.gov (United States)

    Yang, Xing; Liu, Jingjing; McGrouther, Kim; Huang, Huagang; Lu, Kouping; Guo, Xi; He, Lizhi; Lin, Xiaoming; Che, Lei; Ye, Zhengqian; Wang, Hailong

    2016-01-01

    Biochar is a carbon-rich solid material derived from the pyrolysis of agricultural and forest residual biomass. Previous studies have shown that biochar is suitable as an adsorbent for soil contaminants such as heavy metals and consequently reduces their bioavailability. However, the long-term effect of different biochars on metal extractability or soil health has not been assessed. Therefore, a 1-year incubation experiment was carried out to investigate the effect of biochar produced from bamboo and rice straw (at temperatures ≥500 °C) on the heavy metal (cadmium (Cd), copper (Cu), lead (Pb), and zinc (Zn)) extractability and enzyme activity (urease, catalase, and acid phosphatase) in a contaminated sandy loam paddy soil. Three rates (0, 1, and 5%) and two mesh sizes (biochar applications were investigated. After incubation, the physicochemical properties, extractable heavy metals, available phosphorus, and enzyme activity of soil samples were analyzed. The results demonstrated that rice straw biochar significantly (P biochar significantly (P biochar application rate increased. The heavy metal extractability was significantly (P water-soluble organic carbon, and available phosphorus in soil. The 5% application rate of fine rice straw biochar resulted in the greatest reductions of extractable Cu and Zn, 97.3 and 62.2%, respectively. Both bamboo and rice straw biochar were more effective at decreasing extractable Cu and Pb than removing extractable Cd and Zn from the soil. Urease activity increased by 143 and 107% after the addition of 5% coarse and fine rice straw biochars, respectively. Both bamboo and rice straw biochars significantly (P biochar had greater potential as an amendment for reducing the bioavailability of heavy metals in soil than that of the bamboo biochar. The impact of biochar treatment on heavy metal extractability and enzyme activity varied with the biochar type, application rate, and particle size. PMID:25772863

  6. Contribution to heavy metal monitoring (Zn, Cd, Hg, Cu, Ag, Pb, Cr, Ni) at the Baltic coast of Schleswig-Holstein using common mussels (1988/89)

    International Nuclear Information System (INIS)

    Heavy metal concentrations (Zn, Cd, Hg, Cu, Ag, Pb, Cr, Ni) in common mussels were measured at various sites along the Baltic coast of Schleswig-Holstein during different seasons in the period from 1988 to 1989. Measurements of heavy metal load in the summer of 1988/89 showed that Zn concentrations (150-900 μg.g-1) were the highest at all monitoring stations. Hg, Cu, and Ag levels were distinctly elevated and Pb levels only moderately so. Cd, Cr, and Ni levels were largely lower than the aforementioned. A comparison with data of 1979 show a marked rise in Hg levels at all stations and a more or less distinct upward trend for Cr, Zn, Ag, and Ni. Cd levels have markedly declined since 1975/76. (orig.)

  7. Bioacumulation and ultrastructural effects of Cd, Cu, Pb and Zn in the moss Scorpiurum circinatum (Brid.) Fleisch. and Loeske

    International Nuclear Information System (INIS)

    This paper tested if culturing the moss Scorpiurum circinatum (Brid.) Fleisch. and Loeske with metal solutions (Cd, Cu, Pb and Zn) for 30 days causes metal bioaccumulation and ultrastructural changes. The results showed that despite the high heavy metal concentrations in treatment solutions, treated samples did not show severe ultrastructural changes and cells were still alive and generally well preserved. Bioaccumulation highlighted that moss cells survived to heavy metal toxicity by immobilizing most toxic ions extracellularly, likely in binding sites of the cell wall, which is the main site of metal detoxification. - Highlights: ► Ultrastructural effects of metal ions on moss cells are not severe. ► Plastids are the main target of heavy metal pollution. ► Moss cells survive to metal toxicity by immobilizing most toxic ions extracellularly. - Moss cells survive to heavy metal toxicity by immobilizing most toxic ions extracellularly.

  8. Determination of mobile form contents of Zn, Cd, Pb and Cu in soil extracts by combined stripping voltammetry

    International Nuclear Information System (INIS)

    The amount of mobile forms of Zn, Pb, Cd and Cu in extracts obtained by treating soil samples with ammonium nitrate were determined by an appropriate combination of anodic and cathodic stripping voltammetry with hanging mercury drop electrode. Every analysis required three mercury drops: on the first one, zinc was determined; on the second, cadmium and lead; on the third, copper was determined. Zinc, lead and cadmium were determined by conventional differential-pulse anodic stripping voltammetry. For copper determination, adsorptive differential-pulse cathodic stripping voltammetry with amalgamation using chloride ions as a complexing agent was applied. The standard deviation of the results was from 1 to 10% depending on the metal content in the sample. Voltammetric results were in good agreement with the AAS analysis. No microwave digestion of soil extracts was necessary

  9. Determination of mobile form contents of Zn, Cd, Pb and Cu in soil extracts by combined stripping voltammetry

    Energy Technology Data Exchange (ETDEWEB)

    Nedeltcheva, T. [Department of Analytical Chemistry, University of Chemical Technology and Metallurgy, 8 Kl. Ohridsi Blvd., 1756 Sofia (Bulgaria)]. E-mail: nedel@uctm.edu; Atanassova, M. [Department of Analytical Chemistry, University of Chemical Technology and Metallurgy, 8 Kl. Ohridsi Blvd., 1756 Sofia (Bulgaria); Dimitrov, J. [N. Pushkarov Institute of Soil Science and Agroecology, 7 Shosse Bankya St., 1080 Sofia (Bulgaria); Stanislavova, L. [N. Pushkarov Institute of Soil Science and Agroecology, 7 Shosse Bankya St., 1080 Sofia (Bulgaria)

    2005-01-10

    The amount of mobile forms of Zn, Pb, Cd and Cu in extracts obtained by treating soil samples with ammonium nitrate were determined by an appropriate combination of anodic and cathodic stripping voltammetry with hanging mercury drop electrode. Every analysis required three mercury drops: on the first one, zinc was determined; on the second, cadmium and lead; on the third, copper was determined. Zinc, lead and cadmium were determined by conventional differential-pulse anodic stripping voltammetry. For copper determination, adsorptive differential-pulse cathodic stripping voltammetry with amalgamation using chloride ions as a complexing agent was applied. The standard deviation of the results was from 1 to 10% depending on the metal content in the sample. Voltammetric results were in good agreement with the AAS analysis. No microwave digestion of soil extracts was necessary.

  10. EFFECT OF SOIL PROPERTIES AND A SYNTHETIC MUNICIPAL LANDFILL LEACHATE ON THE RETENTION OF CD, NI, PB, AND ZN IN SOIL AND SEDIMENT MATERIALS

    Science.gov (United States)

    Batch equilibrium metal immobilization studies were conducted using seven soil and sediment materials spiked with varying concentrations of Cd, Ni, Pb, and Zn. The objective was to examine the potential mobility of metals in subsoils of metals-contaminated sites. Soil pH influenc...

  11. Heavy Metals (Cd, Cu, Cr, Pb and Zn) in Meretrix meretrix Roding, Water and Sediments from Estuaries in Sabah, North Borneo

    Science.gov (United States)

    Abdullah, Mohd. Harun; Sidi, Jovita; Aris, Ahmad Zaharin

    2007-01-01

    Concentrations of heavy metals (Cd, Cu, Cr, Pb and Zn) in tissues of Meretrix meretrix Roding (M. meretrix R.), water and sediments from two estuaries were determined. One estuary is located in an urban area of Kota Kinabalu (Likas estuary) and the other in a rural district of Kota Belud (Kota Belud estuary), where both are in Sabah, North of…

  12. Equilibrium and kinetic studies of Pb(II, Cd(II and Zn(II sorption by Lagenaria vulgaris shell

    Directory of Open Access Journals (Sweden)

    Mitić-Stojanović Dragana-Linda

    2012-01-01

    Full Text Available The sorption of lead, cadmium and zinc ions from aqueous solution by Lagenaria vulgaris shell biosorbent (LVB in batch system was investigated. The effect of relevant parameters such as contact time, biosorbent dosage and initial metal ions concentration was evaluated. The Pb(II, Cd(II and Zn(II sorption equilibrium (when 98% of initial metal ions were sorbed was attained within 15, 20 and 25 min, respectively. The pseudo first, pseudo-second order, Chrastil’s and intra-particle diffusion models were used to describe the kinetic data. The experimental data fitted the pseudo-second order kinetic model and intra-particle diffusion model. Removal efficiency of lead(II, cadmium(II and zinc(II ions rapidly increased with increasing biosorbent dose from 0.5 to 8.0 g dm-3. Optimal biosorbent dose was set to 4.0 g dm-3. An increase in the initial metal concentration increases the sorption capacity. The sorption data of investigated metal ions are fitted to Langmuir, Freundlich and Temkin isotherm models. Langmuir model best fitted the equilibrium data (r2 > 0.99. Maximal sorption capacities of LVB for Pb(II, Cd(II and Zn(II at 25.0±0.5°C were 0.130, 0.103 and 0.098 mM g-1, respectively. The desorption experiments showed that the LVB could be reused for six cycles with a minimum loss of the initial sorption capacity.

  13. Removal of Heavy Metals Fe3+, Cu2+, Zn2+, Pb2+, Cr3+ and Cd2+ from Aqueous Solutions by Using Eichhornia Crassipes

    Directory of Open Access Journals (Sweden)

    S.A. Shama

    2010-01-01

    Full Text Available The adsorption capacity of Eichhornia Crassipes towards metal ions such as Fe3+, Cu2+, Zn2+, Pb2+, Cr3+ and Cd2+, was studied. The adsorption capacity was investigated by batch experiments. The results showed that the removal percentages increased as the weight of sorbent increased, except for Fe3+ and Zn2+. The effect of contact time was also studied and the results showed that the removal percentages increased as the contact time increased for Cr3+, Zn2+ and Pb2+, but for Fe3+, Cu2+ and Cd2+ the removal decreased. The effect of pH of the solution was also studied and the removal percentages increased as pH increased. Also the effect of the initial concentration of metal ions was studied at four different concentrations (5, 10, 30, 50 mg/L; in case of metal ions (Cu2+, Zn2+ and Cd2+ the removal percentages increased by increasing initial concentration. But, for the other metal ions it decreased by increasing initial concentration over 30 mg/L. The order of increasing removal percentages of metal ions at pH=4.86, initial concentration of metal ions 30 mg/L, and after four hours of shaking was: Cu2+< Cr3+ <Cd2+< Zn2+ <Pb2+

  14. Investigation on Fe, Mn, Zn, Cu, Pb and Cd fractions in the natural surface coating samples and surficial sediments in the Songhua River, China

    Institute of Scientific and Technical Information of China (English)

    GUO Shu-hai; WANG Xiao-li; LI YU; CHEN Jie-jiang; YANG Jun-cheng

    2006-01-01

    Natural surface coating samples (NSCSs) from the surface of shingles and surficial sediments (SSs) in the Songhua River,China were employed to investigate the relationship between NSCSs and SSs in fractions of heavy metals (Fe, Mn, Zn, Cu, Pb, and Cd) using the modified sequential extraction procedure (MSEP). The results show that the differences between NSCSs and SSs in Fe fractions were insignificant and Fe was dominantly present as residual phase (76.22% for NSCSs and 80.88% for SSs) and Fe-oxides phase (20.33% for NSCSs and 16.15% for SSs). Significant variation of Mn distribution patterns between NSCSs and SSs was observed with Mn in NSCSs mainly present in Mn-oxides phase (48.27%) and that in SSs present as residual phase (45.44%). Zn, Cu,Pb and Cd were found dominantly in residual fractions (>48%), and next in solid oxides/hydroxides for Zn, Pb and Cd and in easily oxidizable solids/compounds form for Cu, respectively. The heavy metal distribution patterns implied that Fe/Mn oxides both in NSCSs and SSs were more important sinks for binding and adsorption of Zn, Pb and Cd than organic matter (OM), and inversely,higher affinity of Cu to OM than Fe/Mn oxides in NSCSs and SSs was obtained. Meanwhile, it was found that the distributions of heavy metals in NSCSs and SSs were similar to each other and the pseudo-total concentrations of Zn, Cu, Pb and Cd in NSCSs were greater than those in SSs, highlighting the more importance for NSCSs than SSs in controlling behaviours of heavy metals in aquatic environments.

  15. An inter-laboratory study to test the ability of amendments to reduce the availability of Cd, Pb, and Zn in situ

    International Nuclear Information System (INIS)

    An international inter-laboratory research program investigated the effectiveness of in situ remediation of soils contaminated by cadmium, lead and zinc, measuring changes in soil and soil solution chemistry, plants and soil microbiota. A common soil, from mine wastes in Jasper County MO, was used. The soil was pH 5.9, had low organic matter (1.2 g kg-1 C) and total Cd, Pb, and Zn concentrations of 92, 5022, and 18 532 mg kg-1, respectively. Amendments included lime, phosphorus (P), red mud (RM), cyclonic ashes (CA), biosolids (BIO), and water treatment residuals (WTR). Both soil solution and NH4NO3 extractable metals were decreased by all treatments. Phytotoxicity of metals was reduced, with plants grown in P treatments having the highest yields and lowest metal concentration (0.5, 7.2 and 406 mg kg-1 Cd, Pb, and Zn). Response of soil micro-organisms was similar to plant responses. Phosphorus addition reduced the physiologically based extraction test Pb from 84% of total Pb extracted in the untreated soil to 34.1%. - Addition of phosphorus to Pb, Zn and Cd contaminated mine waste was able to reduce metal toxicity for a range of biological endpoints

  16. Cd, Cr, Cu, Pb, and Zn concentrations in Ulva lactuca, Codium fragile, Jania rubens, and Dictyota dichotoma from Rabta Bay, Jijel (Algeria).

    Science.gov (United States)

    Laib, Essaid; Leghouchi, Essaid

    2012-03-01

    Concentrations of Cd, Cr, Cu, Pb, and Zn were determined in algae samples collected from the Rabta Bay in the Mediterranean Sea, Algeria. The levels of heavy metals in the macroalgae, Ulva lactuca, Codium fragile (green algae), Jania rubens (red algae), and Dictyota dichotoma (brown algae) recorded high concentrations except for Cd. Moreover, Zn was the most predominant metal in the seaweeds. The obtained HM contents indicate that different species demonstrate various degree of metal accumulation and the obtained higher values in site 1 of the studied zone can be attributed to the discharge influence of two rivers (Mouttas and Larayeche Rivers), entering the Mediterranean Sea and local pollutant emissions. The abundance of heavy metal concentrations in the macroalgae samples was found in the order below: Zn > Cu > Pb > Cr > Cd from the studied zone. The highest amounts of heavy metals in algae samples were Cd, Cu, and Pb in brown algae, and Cr and Zn in green and brown algae from the studied zone (Rabta Bay). PMID:21755430

  17. Sub-cellular partitioning of Zn, Cu, Cd and Pb in the digestive gland of native Octopus vulgaris exposed to different metal concentrations (Portugal)

    Energy Technology Data Exchange (ETDEWEB)

    Raimundo, J. [National Institute for Agronomy and Fisheries Research - IPIMAR, Av. Brasilia, 1449-006 Lisbon (Portugal)], E-mail: jraimundo@ipimar.pt; Vale, C. [National Institute for Agronomy and Fisheries Research - IPIMAR, Av. Brasilia, 1449-006 Lisbon (Portugal); Duarte, R.; Moura, I. [REQUIMTE - CQFB, Department of Chemistry, Faculty of Sciences and Technology, New University of Lisbon, Qta Torre, 2829-516 Monte da Caparica (Portugal)

    2008-02-15

    Concentrations of Zn, Cu, Cd and Pb and their sub-cellular distributions were determined in composite samples of digestive glands of the common octopus, Octopus vulgaris caught from two areas of the Portuguese coast characterised by contrasting metal contamination. Minor contents of Zn (1%), Cu (2%), Cd (6%) and Pb (7%) were found in the insoluble fraction, consisting of nuclei, mitochondria, lysosomes and microsome operationally separated from the whole digestive gland through a sequential centrifugation. A tendency for linear relationships between metal concentrations in nuclei, mitochondria, lysosomes and whole digestive gland was observed. These relationships suggest that despite low metal content organelles responded to the increasing accumulated metals, which means that detoxifying mechanism in cytosol was incomplete. Poorer correlations between microsome and whole digestive gland did not point to metal toxicity in the analysed compartments. However, the high accumulated Cd indicated that O. vulgaris is an important vehicle of this element to its predators in the coastal environment.

  18. Immobilization of Pb, Cd, and Zn in a contaminated soil using eggshell and banana stem amendments: metal leachability and a sequential extraction study.

    Science.gov (United States)

    Ashrafi, Mehrnaz; Mohamad, Sharifah; Yusoff, Ismail; Shahul Hamid, Fauziah

    2015-01-01

    Heavy-metal-contaminated soil is one of the major environmental pollution issues all over the world. In this study, two low-cost amendments, inorganic eggshell and organic banana stem, were applied to slightly alkaline soil for the purpose of in situ immobilization of Pb, Cd, and Zn. The artificially metal-contaminated soil was treated with 5% eggshell or 10% banana stem. To simulate the rainfall conditions, a metal leaching experiment for a period of 12 weeks was designed, and the total concentrations of the metals in the leachates were determined every 2 weeks. The results from the metal leaching analysis revealed that eggshell amendment generally reduced the concentrations of Pb, Cd, and Zn in the leachates, whereas banana stem amendment was effective only on the reduction of Cd concentration in the leachates. A sequential extraction analysis was carried out at the end of the experiment to find out the speciation of the heavy metals in the amended soils. Eggshell amendment notably decreased mobility of Pb, Cd, and Zn in the soil by transforming their readily available forms to less accessible fractions. Banana stem amendment also reduced exchangeable form of Cd and increased its residual form in the soil. PMID:25060308

  19. Distribution and speciation of metals (Cu, Zn, Cd, and Pb) in agricultural and non-agricultural soils near a stream upriver from the Pearl River, China

    International Nuclear Information System (INIS)

    The distribution and chemical speciation of typical metals (Cu, Zn, Cd and Pb) in agricultural and non-agricultural soils were investigated in the area of Nanpan River, upstream of the Pearl River. The investigated four metals showed higher concentrations in agricultural soils than in non-agricultural soils, and the site located in factory district contained metals much higher than the other sampling sites. These observations suggested that human activities, such as water irrigation, fertilizer and pesticide applications might have a major impact on the distribution of metals. Metal speciation analysis presented that Cu, Zn and Cd were dominated by the residual fraction, while Pb was dominated by the reducible fraction. Because of the low mobility of the metals in the investigated area, no remarkable difference could be observed between upstream and downstream separated by the factory site. -- Highlights: ► Agricultural soils contain higher metal concentrations than non-agricultural soils. ► The site located in the factory district has the highest metal concentration. ► Cu, Zn and Cd are dominated by residual fraction, and Pb by reducible fraction. ► Cd pollution should not be overlooked in soils upstream of Pearl River. -- The mobility of four investigated metals is low but Cd pollution should not be overlooked in soils upstream of Pearl River

  20. Toxic Metals (Pb and Cd and Their Respective Antagonists (Ca and Zn in Infant Formulas and Milk Marketed in Brasilia, Brazil

    Directory of Open Access Journals (Sweden)

    José G. Dórea

    2010-11-01

    Full Text Available In non-ideal scenarios involving partial or non-breastfeeding, cow’s milk-based dairy products are mainstream in infant feeding. Therefore, it is important to study the concentrations of potentially neurotoxic contaminants (Pb and Cd and their respective counteracting elements (Ca and Zn in infant dairy products. Fifty-five brands of infant formulas and milk sold in Brasilia, Brazil were analyzed. The dairy products came from areas in the central-west (26%, southeast (29% and south of Brazil (36% extending as far as Argentina (7% and the Netherlands (2%. For toxic Pb and Cd, median concentrations in powdered samples were 0.109 mg/kg and 0.033 mg/kg, respectively; in fluid samples median Pb concentration was 0.084 mg/kg, but median Cd concentration was below the limit of detection and overall values were below reference safety levels. However, 62% of these samples presented higher Pb concentration values than those established by FAO/WHO. Although the inverse correlation between Cd and Zn (Spearman r = −0.116; P = 0.590 was not statistically significant, the positive correlation between Ca and Pb was (Spearman r = 0.619; P < 0.0001. Additionally, there was a significant correlation between Pb and Cd. Furthermore, the study also revealed that provision of the essential trace element Zn in infant formulas can provide adequate amounts of the recommended daily requirements. Infant formulas and milk sold for consumption by infants and children can be an efficient tool to monitor neurotoxic metal risk exposure among young children.

  1. Sensitive electrochemical sensor using a graphene–polyaniline nanocomposite for simultaneous detection of Zn(II), Cd(II), and Pb(II)

    International Nuclear Information System (INIS)

    Highlights: • Detection limits for Zn, Pb, and Cd using ASV were 1, 0.1, and 0.1 μg L−1, respectively. • G/PANI-modification led to a 3× improvement in signal vs. unmodified electrodes. • ASV on a plastic substrate exhibited better sensitivity than on a paper substrate. • Zn, Pb, and Cd were measured in human serum using method of standard addition. - Abstract: This work describes the development of an electrochemical sensor for simultaneous detection of Zn(II), Cd(II), and Pb(II) using a graphene–polyaniline (G/PANI) nanocomposite electrode prepared by reverse-phase polymerization in the presence of polyvinylpyrrolidone (PVP). Two substrate materials (plastic film and filter paper) and two nanocomposite deposition methods (drop-casting and electrospraying) were investigated. Square-wave anodic stripping voltammetry currents were higher for plastic vs. paper substrates. Performance of the G/PANI nanocomposites was characterized by scanning electron microscopy (SEM) and cyclic voltammetry. The G/PANI-modified electrode exhibited high electrochemical conductivity, producing a three-fold increase in anodic peak current (vs. the unmodified electrode). The G/PANI-modified electrode also showed evidence of increased surface area under SEM. Square-wave anodic stripping voltammetry was used to measure Zn(II), Cd(II), and Pb(II) in the presence of Bi(III). A linear working range of 1–300 μg L−1 was established between anodic current and metal ion concentration with detection limits (S/N = 3) of 1.0 μg L−1 for Zn(II), and 0.1 μg L−1 for both Cd(II) and Pb(II). The G/PANI-modified electrode allowed selective determination of the target metals in the presence of common metal interferences including Mn(II), Cu(II), Fe(III), Fe(II), Co(III), and Ni(II). Repeat assays on the same device demonstrated good reproducibility (%RSD < 11) over 10 serial runs. Finally, this system was utilized for determining Zn(II), Cd(II), and Pb(II) in human serum using the

  2. STUDY ON PHYTOEXTRACTION BALANCE OF ZN, CD, PB FROM MINE-WASTE POLLUTED SOILS BY USING MEDICAGO SATIVA AND TRIFOLIUM PRATENSE SPECIES

    Directory of Open Access Journals (Sweden)

    B. LIXANDRU

    2013-07-01

    Full Text Available For a term of two years was studied phytoextractive potential of Zn, Cd and Pb using successive culture of alfalfa (Medicago sativa and red clover (Trifolium pratense. In the experimental plot was incorporated a quantity of 20 kg mine waste per square meter, providing in soil 1209 mg Zn/kg d.s., 4.70 mg Cd/kg d.s. and 188.2 mg Pb/kg d.s. The metals content accumulated in plants was determined at the two moments of biomass harvesting, and through balance calculations we could establish the phytoextraction efficiency of the two forage-grasses species. The obtained results indicate that both perennial forage-legumes species have a good phytoextractive capacity and tolerance for Zn and Pb, especially Trifolium pratense specie. By using this species as phytoextractors on soil polluted with 3.76 times more Pb and 4.03 times more Zn, is provided the reduction of metallic ions concentration in soil to limits admitted by laws in a period of 3, respectively, 4 years.

  3. An Assessment of the Accumulation Potential of Pb, Zn and Cd by Avicennia marina (Forssk. Vierh. in Vamleshwar Mangroves, Gujarat, India

    Directory of Open Access Journals (Sweden)

    Isaiah Nirmal KUMAR

    2011-03-01

    Full Text Available The study deals with the accumulation of Pb, Zn and Cd in an important mangrove species, Avicennia marina (Forssk. Vierh., in the Vamleshwar mangrove ecosystem, near Narmada estuary, West coast of Gujarat, India with height differences of 0.5, 1.5, 2.5 meters and carried out under field conditions during October, 2009. The site was located on 21�30�11.55�� N latitude and 72�43�53.68�� E longitude. Mangrove receives heavy metal pollution from upstream areas of Narmada estuary and highly populated settlements. However, little is known about the capacity of mangrove plants to take up and store heavy metals in them. Water, sediment and plant parts such as roots, stems and leaves were analyzed for finding the trace metal accumulation of different height groups by Inductive Coupled Plasma Analyser (ICPA. Amount of the content of metals found in the water, sediment and plant parts were in the order of Pb>Zn>Cd. The average contents of heavy metals in the waters were 57.83 mg l-1 for Pb, 3.89 83 mg l-1 for Zn and 0.42 mg l-1 for Cd. It was observed that the average contents of Pb (73.6 mg l-1, Zn (8.1 mg l-1 and Cd (0.73 mg l-1 in the sediments were below the critical soil concentrations. The concentrations of heavy metals in different parts of Avicennia marina were in the order Roots>stem>leaf except for Cd, but Cd found higher in leaf. The ranges of the content of heavy metals in plants were 18.5-102.2 mg l-1 for Pb, 3.5-19.5 mg l-1 for Zn and 0.2-4.1 mg l-1 for Cd. The concentrations of all heavy metals in Avicennia marina except Pb were falling within the normal range and were much more in the plants have the highest height. The present study has shown the potential of Avicennia marina as a phytoremediation species for selected heavy metals in many mangrove ecosystems.

  4. Retention efficiency of Cd, Pb and Zn from agricultural by-products activated carbon and biochar under laboratory conditions

    Science.gov (United States)

    Coscione, Aline; Ramos, Barbara

    2015-04-01

    The immobilization of inorganic contaminants by using biochar in soils has played an increasingly important role and it is seen as an attractive alternative for the remediation of heavy metals. Although, the production of activated carbon (CA) from agricultural by-products has received special attention, the activation of the the organic source has been studied in order to increase its porposity, surface area and chemical polarity, resulting in higher adsorption of metals. Therefore, this study aimed to evaluate the effectiveness of BC and CA samples, obtained from a eucalyptus husks and cane sugar bagasse after activation with 20% phosphoric acid and pyrolyzed at 450oC in the retention of Zn, Cd and Pb using contaminated individual solutions. The experiment was performed using samples of activated carbon of eucalyptus husk (CCA), eucalyptus husk biochar (BC), activated carbon of sugar cane bagasse (CBA) and sugar cane bagasse biochar (BB) previously treated with Zn, Cd (range of tested solution from 0.1 up to 12 mmol L-1) and Pb (from 0.1 up 50 mmol L-1) which were submitted to stirring with ammonium acetate solution at pH 4.9 for 48 h. The results obtained were adjusted with Langmuir desorptiom isotherms. The pH of the resulting solution, were the meatls were analyse, was measure and remained in the range 4.9 - 5.0. The lower pH found in activated samples (range 2.4-2.5) resulted in larger desorption of metals than the biochar samples (pH of 9.7 for BC and 7.0 for BB). This result is surprising since for the biochar samples it was expected that any precipated metals were dissolved by the desorption solution in addition to metals released by ion exchange. Although the desorption results of activated samoels is still unclear, hich we belive may be explaibed by some adicitonal insterumental analysis, biochar samples showed better potential for application in contaminated soils than the previous.

  5. Simultaneous determination of Cd(II), Cu(II), Pb(II), and Zn(II) in citrus essential oils by derivative potentiometric stripping analysis.

    Science.gov (United States)

    La Pera, Lara; Saitta, Marcello; Di Bella, Giuseppa; Dugo, Giacomo

    2003-02-26

    Citrus essential oils are widely used in the food, cosmetics, and pharmaceutical industries, so the determination of heavy metals content is of great importance to guarantee their quality. The present work deals with the quantification of Cd(II), Cu(II), Pb(II), and Zn(II) in different varieties of citrus essential oils, using derivative potentiometric stripping analysis. Two different metals extraction procedures, involving concentrated hydrochloric acid treatment and acid-alcoholic dissolution, are tested on lemon, mandarin, sweet orange, and bergamot essential oils, and they give very similar results. Cd(II), Cu(II), Pb(II), and Zn(II) recovery tests spanned from 95 to 100.50%, providing evidence that metals quantification remained unaffected by the cleanup steps of the two procedures. The repeatability of the hydrochloric acid extraction method, applied on different varieties of essential oils, is >95.00% for Cd(II), Cu(II), Pb(II), and Zn(II), whereas the repeatability of the acid-alcoholic dissolution method is >93.00% for Cu and Cd only in lemon oil. Detection limits obtained for the four analytes, using both procedures, ranged from 0.10 to 0.98 ng g(-)(1) in lemon, mandarin, sweet orange, and bergamot essential oils. PMID:12590445

  6. Soils from sites of historical metal mining in western Małopolska (S Poland are strongly contaminated with Zn, Pb and Cd

    Directory of Open Access Journals (Sweden)

    Stefanowicz A. M.

    2013-04-01

    Full Text Available Concentrations of Cd, Pb and Zn in soils developed at 63 sites of historical metal mining in western Małopolska (S Poland were estimated. Heavy metal concentrations were measured with an atomic absorption spectrometer after wet digestion in hot HClO4 (total forms, extraction in 0.1 M BaCl2 (exchangeable forms or in water (water-soluble forms. Basic soil properties such as texture, C, N, Ca contents and pH were also measured. Total concentrations of Cd in soil varied from 4.4 to 392, Pb from 72.8 to 16931 and Zn from 322 to 41860 mg kg−1. Exchangeable Cd, Pb and Zn extended from 0 to 19.3 %, from 0 to 0.2 % and from 0 to 3.5 % of the total metal forms, respectively, indicating that Cd is the most mobile and potentially bioavailable metal. In turn, water-soluble metal forms did not exceed 1 % of the total. Our study showed that soils developed at sites of historical metal mining are severely polluted with heavy metals. Old heaps threaten not only the environment, but also local inhabitants, as they are often located in a close proximity to houses or agricultural fields.

  7. Influence of thermal treatment on bentonite used as adsorbent for Cd, Pb, Zn retention from mono-solute and poly-solute aqueous solutions

    Directory of Open Access Journals (Sweden)

    Susana Yamila Martinez Stagnaro

    2012-08-01

    Full Text Available The retentions of Zn, Cd and Pb cations by one treated bentonite up to 750 °C were analyzed. The retentions were evaluated by using mono-and poly-solute aqueous solutions of such cations. The adsorptions were carried out in batch system at room temperature. The solid/liquid ratio was 2% wt.v-1. The solids were characterized by X-ray diffraction, thermal and chemical analyses. The Zn cation from mono- or polysolute-solutions was retained in higher amount than Cd and Pb cations in similar solution types by bentonite. The retentions were effective up to 450 °C calcined bentonite, after that, the retention capacity decreased in concordance with dehydroxylation of the structure of clay minerals.

  8. Distribution of heavy metals (Pb, Cd, and Zn) in sediment profiles associated to Rhizophora mangle in Sevilla River - Cienaga Grande de Santa Marta, Colombia

    International Nuclear Information System (INIS)

    In order to evaluate the vertical distribution of the heavy metals Pb, Cd, and Zn in sediments associated to Rhizophora mangle plants, potentially bioavailable and not bioavailable concentrations of these metals were determined in three sediment cores collected in the Sevilla River, Cienaga Grande de Santa Marta. Measurements were carried out by inductively coupled plasma-atomic emission spectrometry. The results showed that in Sevilla River mangrove ecosystem these metals are accumulated principally in non-bioavailable forms, this means that a great part or them are retained in the sediment. The retention of Pb, Cd, and Zn in the sediments of this mangrove ecosystem is strongly related to the physicochemical parameters pH, salinity, and redox potential, and to organic matter, and silt and clays contents

  9. Contamination by Cd, Cu, Pb, and Zn in mine wastes from abandoned metal mines classified as mineralization types in Korea.

    Science.gov (United States)

    Jung, Myung Chae

    2008-06-01

    The objective of this study was to investigate heavy metal contamination and geochemical characteristics of mine wastes, including tailings, from 38 abandoned mines classified as five mineralization types. Mine waste materials including tailings and soils were sampled from the mines and the physical and chemical characteristics of the samples were analyzed. The particle size of tailings was in the range of 10-100 microm. The pH of the waste covered a wide range, from 1.73 to 8.11, and was influenced by associated minerals and elevated levels of Cd, Cu, Pb, and Zn, extracted by a Korean Standard Method (digestion with 0.1 mol L(-1) HCl), which were found in the wastes. Half of the samples contained heavy metals at levels above those stipulated by the Soil Environmental Conservation Act (SECA) in Korea. In addition, extremely high concentrations of the metals were also found in mine wastes extracted by aqua regia, especially those from mines associated with sulfide minerals. Thus, it can be expected that trace elements in mine wastes may be dispersed both downstream and downslope through water and wind. Eventually they may pose a potential health risk to residents in the vicinity of the mine. It is necessary to control mine wastes by using a proper method for their reclamation, such as neutralization of the mine wastes using a fine-grained limestone. PMID:17687627

  10. Proficiency test PLANTS 8 - determination of As, Cd, Cr, Cu, Hg, Pb, Se and Zn in dry carrot root powder

    International Nuclear Information System (INIS)

    Proficiency test PLANTS 8: determination of As, Cd, Cr, Cu, Hg, Pb, Se and Zn in dry carrot root powder has been described. The proficiency test has been provided by the Institute of Nuclear Chemistry and Technology with cooperation with POLLAB-CHEM/EURACHEM-PL and REFMAT Society according to ISO/IEC Guide 43-1:1997 and IUPAC International Harmonized Protocol (2006). Testing material was prepared from home-grown carrots which were air dried, milled and sieved. Particle fraction below 0.5 mm was collected and bottled in 20 g portions. Homogeneity testing shown that the material was homogenized for sample mass at least 250 mg. Assigned (reference) values and their uncertainties were established on the basis of the results of analysis provided by 3 reference laboratories. The testing samples were send to 25 laboratories participating in the proficiency test. 24 laboratories had send results. The results supplied by the participants were statistically evaluated. Values of z-score, zeta-score and En numbers were used for the evaluation of the participating laboratory performance. (authors)

  11. Trace analysis of Cd, Cu, Pb and Zn in various materials using differential pulse anodic stripping voltammetry

    International Nuclear Information System (INIS)

    Sampling and sample preparation methods have been described. Digestion methods for different types of materials and acid purification systems have been developed. For trace analysis purposes cleaning methods for glassware etc. have been described. Differential pulse anodic stripping voltametric (DPASV) method has been worked out for the trace analysis of zn, cd, pb and Cu in different types of materials. Linearity of the method has been checked by drawing concentration versus currents (peak height) curves. Precision of the method has been checked by analysing a number of actual samples. of the method has been verified by analysing standards of U.S.A. Comparative studies have been done between Differential pulse anodic stripping voltammetric method and Atomic Absorption spectroscopic method. Problems of contamination and systematic errors during trace and ultra-trace analysis have been discussed. A variety of samples including soil, spinach, wheat flour, rice flour, dry milk, coriander, kidney stones, bladder stones etc. have been analysed and preliminary results have been reported. (author)

  12. Zhodnocení aplikací postupů vyluhovatelnosti Zn, Cd, Pb, Cr pro jemnozrnné metalurgické kaly

    OpenAIRE

    Gabor, Roman; Seidlerová, Jana

    2012-01-01

    Evaluation of Leaching Procedures for Zn, Cd, Pb, Cr from Fine Metallurgical Sludges The current assessment of waste hazard is based on the leachability test and determining factors according to the current legislation. To consider the mobility and potential bioavailability TCLP (Toxicity characteristic leaching procedure) procedures according to the U.S. EPA and the sequential extraction according to Tessier and Kersten have been used. It was shown that the current assessment method, based j...

  13. Levels of Cd (II), Mn (II), Pb (II), Cu (II), and Zn (II) in Common Buzzard (Buteo buteo) from Sicily (Italy) by Derivative Stripping Potentiometry

    OpenAIRE

    G. Di Bella; Rando, R.; V. Lo Turco; Naccari, F.; P. Licata; G. Dugo

    2010-01-01

    The purpose of this study was to determine the concentrations of heavy metals (Cd, Pb, Cu, Mn, and Zn) in different organs (liver, kidney, muscle, lung, skin, and feathers) of buzzards (Buteo buteo), utilized as a “biological indicator” for environmental contamination, from different areas of Sicily and to investigate the relationships between birds sex, age, and weight and metal levels in these samples. All samples of common buzzards were collected at the “Recovery Center o...

  14. A test of the stability of Cd, Cu, Hg, Pb and Zn profiles over two decades in lake sediments near the Flin Flon Smelter, Manitoba, Canada

    Energy Technology Data Exchange (ETDEWEB)

    Percival, J.B.; Outridge, P.M., E-mail: outridge@nrcan.gc.ca

    2013-06-01

    Lake sediments are valuable archives of atmospheric metal deposition, but the stability of some element profiles may possibly be affected by diagenetic changes over time. In this extensive case study, the stability of sedimentary Cd, Cu, Hg, Pb and Zn profiles was assessed in dated sediment cores that were collected in 2004 from four smelter-affected lakes near Flin Flon, Manitoba, which had previously been cored in 1985. Metal profiles determined in 1985 were in most cases clearly reproduced in the corresponding sediment layers in 2004, although small-scale spatial heterogeneity in metal distribution complicated the temporal comparisons. Pre-smelter (i.e. pre-1930) increases in metal profiles were likely the result of long-range atmospheric metal pollution, coupled with particle mixing at the 1930s sediment surface. However, the close agreement between key inflection points in the metal profiles sampled two decades apart suggests that metals in most of the lakes, and Hg and Zn in the most contaminated lake (Meridian), were stable once the sediments were buried below the surface mixed layer. Cadmium, Cu and Pb profiles in Meridian Lake did not agree as well between studies, showing evidence of upward remobilization over time. Profiles of redox-indicator elements (Fe, Mn, Mo and U) suggested that the rate of Mn oxyhydroxide recycling within sediment was more rapid in Meridian Lake, which may have caused the Cd, Cu and Pb redistribution. - Highlights: • Sedimentary Cd, Cu, Hg, Pb and Zn profiles in four lakes were mostly unchanged over 19 years. • In one lake, Cd, Cu and Pb profiles were offset relative to the originals. • The offset could indicate diagenetic upcore dispersal of these metals.

  15. Slash-and-char: An ancient agricultural technique holds new promise for management of soils contaminated by Cd, Pb and Zn

    International Nuclear Information System (INIS)

    Heavy metal contamination of agricultural soils is of worldwide concern. Unfortunately, there are currently no efficient and sustainable approaches for addressing this concern. In this study, we conducted a field experiment in which an agricultural soil highly contaminated by cadmium (Cd), lead (Pb) and zinc (Zn) was treated on-site by an ancient agricultural technique, ‘slash-and-char’, that was able to convert the biomass feedstock (rice straw) into biochar in only one day. We found evidence that in comparison to the untreated soil, the treated soil was associated with decreased bioavailability of the heavy metals and increased vegetable yields. Most importantly, the treatment was also coupled with dramatic reductions in concentrations of the heavy metals in vegetables, which made it possible to produce safe crops in this highly contaminated soil. Collectively, our results support the idea that slash-and-char offers new promise for management of soils contaminated by Cd, Pb and Zn. - Highlights: • We explored the potential of slash-and-char in dealing with soil metal pollution. • Metal bioavailability in the soil treated with slash-and-char was reduced by 24–65%. • Vegetable yield in the soil treated with slash-and-char was increased by 34–67%. • Slash-and-char could reduce the metal concentration in vegetables to a safe level. - An ancient agricultural technique called ‘slash-and-char’ offers new promise for management of soils contaminated multiply by Cd, Pb and Zn

  16. Levels of Cd (II, Mn (II, Pb (II, Cu (II, and Zn (II in Common Buzzard (Buteo buteo from Sicily (Italy by Derivative Stripping Potentiometry

    Directory of Open Access Journals (Sweden)

    P. Licata

    2010-01-01

    Full Text Available The purpose of this study was to determine the concentrations of heavy metals (Cd, Pb, Cu, Mn, and Zn in different organs (liver, kidney, muscle, lung, skin, and feathers of buzzards (Buteo buteo, utilized as a “biological indicator” for environmental contamination, from different areas of Sicily and to investigate the relationships between birds sex, age, and weight and metal levels in these samples. All samples of common buzzards were collected at the “Recovery Center of Wild Fauna” of Palermo, through the Zooprophilactic Institute. Potentiometric stripping analysis (PSA was used to determine the content of Cd(II, Cu(II, Mn(II, Pb(II, and Zn(II in bird tissues. For toxic metals, the highest levels of Pb were in liver and those of Cd in lung; Zn levels were higher than Cu and Mn in all tissues analyzed. The concentrations in liver, lung, kidney, and muscle could be considered as an indicative of chronic exposure to metals while the presence of metals in skin could be consequential to storing and elimination processes. The found concentrations of metals in the studied matrices required a highly sensitive method for their determination and a simple sample preparation procedure, and the proposed method was well suited for this purpose.

  17. An intermediate complexity dynamic model for predicting accumulation of atmospherically-deposited metals (Ni, Cu, Zn, Cd, Pb) in catchment soils: 1400 to present

    International Nuclear Information System (INIS)

    The Intermediate Dynamic Model for Metals (IDMM) is a model for prediction of the pools of metals (Ni, Cu, Zn, Cd, Pb) in topsoils of catchments resulting from deposition of metals from the atmosphere. We used the model to simulate soil metal pools from 1400 onwards in ten UK catchments comprising semi-natural habitats, and compared the results with present day observations of soil metal pools. Generally the model performed well in simulating present day pools, and further improvements were made to simulations of Ni, Cu, Zn and Cd by adjusting the strength of metal adsorption to the soils. Some discrepancies between observation and prediction for Pb appeared to be due either to underestimation of cumulative deposition, or to overestimation of the metal pool under ‘pristine’, pre-industrial conditions. The IDMM provides a potential basis for large scale assessment of metal dynamics in topsoils. -- Highlights: •The Intermediate Dynamic Model for Metals (IDMM) is a new model for long term metal dynamics in semi-natural catchments. •The model describes well current day metal pools in ten semi-natural catchments of the UK. •The IDMM has clear potential for large scale simulation of metal dynamics in soils. -- The Intermediate Dynamic Model for Metals predicts the present day pools of Ni, Cu, Zn, Cd and Pb in semi-natural catchment soils of the UK

  18. Levels of Cd (II), Mn (II), Pb (II), Cu (II), and Zn (II) in Common Buzzard (Buteo buteo) from Sicily (Italy) by Derivative Stripping Potentiometry

    International Nuclear Information System (INIS)

    The purpose of this study was to determine the concentrations of heavy metals (Cd, Pb, Cu, Mn, and Zn) in different organs (liver, kidney, muscle, lung, skin, and feathers) of buzzards (Buteo buteo), utilized as a biological indicator for environmental contamination, from different areas of Sicily and to investigate the relationships between birds sex, age, and weight and metal levels in these samples. All samples of common buzzards were collected at the Recovery Center of Wild Fauna of Palermo, through the Zooprophilactic Institute. Potentiometric stripping analysis (PSA) was used to determine the content of Cd(II), Cu(II), Mn(II), Pb(II), and Zn(II) in bird tissues. For toxic metals, the highest levels of Pb were in liver and those of Cd in lung; Zn levels were higher than Cu and Mn in all tissues analyzed. The concentrations in liver, lung, kidney, and muscle could be considered as an indicative of chronic exposure to metals while the presence of metals in skin could be consequential to storing and elimination processes. The found concentrations of metals in the studied matrices required a highly sensitive method for their determination and a simple sample preparation procedure, and the proposed method was well suited for this purpose.

  19. Bioaccumulation and associated dietary risks of Pb, Cd, and Zn in amaranth (Amaranthus cruentus) and jute mallow (Corchorus olitorius) grown on soil irrigated using polluted water from Asa River, Nigeria.

    Science.gov (United States)

    Ogunkunle, Clement Oluseye; Ziyath, Abdul M; Adewumi, Faderera Esther; Fatoba, Paul Ojo

    2015-05-01

    Dietary uptake of heavy metals through the consumption of vegetables grown on polluted soil can have serious human health implications. Thus, the study presented in this paper investigated the bioaccumulation and associated dietary risks of Pb, Zn, and Cd present in vegetables widely consumed in Nigeria, namely amaranth and jute mallow, grown on soil irrigated with polluted water from Asa River. The study found that the soil was polluted with Zn, Pb, and Cd with Pb and Cd being contributed by polluted river, while Zn was from geogenic sources. The metal concentration in amaranth and jute mallow varied in the order of Zn > Pb > Cd and Zn > Pb ≈ Cd, respectively. Jute mallow acts as an excluder plant for Pb, Cd, and Zn. Consequently, the metal concentrations in jute mallow were below the toxic threshold levels. Furthermore, non-cancer human health risk of consuming jute mallow from the study site was not significant. In contrast, the concentrations of Pb and Cd in amaranth were found to be above the recommended safe levels and to be posing human health risks. Therefore, further investigation was undertaken to identify the pathways of heavy metals to amaranth. The study found that the primary uptake pathway of Pb and Cd by amaranth is foliar route, while root uptake is the predominant pathway of Zn in amaranth. PMID:25899541

  20. Chemical speciation of Fe, Mn, Pb, Zn, Cd, Cu, Co, Ni and Cr in the suspended particulate matter off the Mejerda River Delta (Gulf of Tunis, Tunisia)

    Science.gov (United States)

    Helali, Mohamed Amine; Oueslati, Walid; Zaaboub, Noureddine; Added, Ayed; Aleya, Lotfi

    2016-06-01

    Fluxes of suspended particulate matter (SPM) and their associated metals were performed off the Mejerda River Delta during both the wet (March) and the dry (July) seasons in 2012, using sediment traps at study stations at depths of 10, 20 and 40 m. Fluxes nearest to the Mejerda outlet were more significant, especially during winter (36 g m-2 day-1), but dissipated further offshore, 24.5-6 g m-2 day-1 at the 20 m and 21.8-4.8 g m-2 day-1 at the 40 m stations. Many variations observed in seasonal and spatial metal fluxes are similar to those of SPM, in particular Pb and Zn, probably because they are associated with the mining activity characteristic of the Mejerda catchment. Chemical speciation reveals that most of the metals (20-100%) are bound to the residual fraction. The most toxic metals (Pb, Zn) are bound in part to the exchangeable fraction (20-50% for Pb and 5-15% for Zn) making them relatively bioavailable and therefore potentially toxic. While Cu and Cd fluxes are not always clearly established according to season, both metals are apparently sequestered deep in the sediment, bound especially to clays (40-80% for Cd and up to 100% for Cu).

  1. Impact of shallowly deposited ore-bearing dolomites on local soil pollution aureoles of As, Cd, Pb, and Zn in an old mining area

    Energy Technology Data Exchange (ETDEWEB)

    Fabijanczyk, Piotr; Zawadzki, Jaroslaw [Warsaw Univ. of Technology (Poland). Environmental Engineering Faculty

    2012-10-15

    The study area, located in Upper Silesian Industrial Region, was rich in significant amounts of ores that were classified of Mississippi Valley type. Being these ores especially rich in Pb and Zn, an intense development of mining and ore extraction industry was verified in this area. The goal of this study was to investigate how local pollution aureoles of As, Cd, Pb, and Zn were influenced by the presence of shallowly deposited ore-bearing dolomites. Very extensive sampling campaign was carried out, and over 1,000 samples were collected in the area of about 150 km{sup 2}. Local aureoles of investigated metals were calculated for two soil layers. The first one covered the part of soil core from the soil surface to the depth of 20 cm and the second one from the depth of 40 cm to the depth of 60 cm. All spatial distributions of particular metals in soil were calculated by means of ordinary kriging using free softwares QGIS and SAGA. Maximum concentrations of Pb and Zn in soil in study area were very high, reaching over 24,000 and 77,000 mg/kg, respectively. Maximum concentrations of As and Cd were also very high, reaching about 1,000 mg/kg. Those maximum values were observed in the direct vicinity of the Boles?aw mine and its mine dumps. Almost all local aureoles were located within the range of ore-bearing dolomites. It was especially visible for Pb and Zn, minerals very common in ore deposits. Otherwise, local aureoles of As and Cd were more related with the vicinity of mines and other pollution sources, being more associated to the anthropogenic pollution than to the presence of ore-bearing dolomites. The aureoles of Pb and Zn, and in moderate degree of As, were associated with a mineral composition of ores. Differently, the location, the shape, and spatial pattern of Cd aureoles suggest that they were mostly influenced by anthropogenic pollution. Anthropogenic factors were dominating over the lithogenic ones and masking the influence of the shallowly deposited

  2. Impact of temperature on the dynamics of organic matter and on the soil-to-plant transfer of Cd, Zn and Pb in a contaminated agricultural soil.

    Science.gov (United States)

    Cornu, Jean-Yves; Denaix, L; Lacoste, J; Sappin-Didier, V; Nguyen, C; Schneider, A

    2016-02-01

    Predicting the soil-to-plant transfer of metals in the context of global warming has become a major issue for food safety. It requires a better understanding of how the temperature alters the bioavailability of metals in cultivated soils. This study focuses on one agricultural soil contaminated by Cd, Zn and Pb. DGT measurements were performed at 10, 20 and 30 °C to assess how the bioavailability of metals was affected by a rise in soil temperature. A lettuce crop was cultivated in the same conditions to determine if the soil-to-plant transfer of metals increased with a rise in soil temperature. A gradual decline in Cd and Zn bioavailability was observed from 10 to 30 °C, which was attributed to more intense complexation of metals in the pore water at higher temperatures. Together with its aromaticity, the affinity of dissolved organic matter (DOM) for metals was indeed suspected to increase with soil temperature. One main output of the present work is a model which satisfactorily explains the thermal-induced changes in the characteristics of DOM reported in Cornu et al. (Geoderma 162:65-70, 2011) by assuming that the mineralization of initial aliphatic compounds followed a first-order reaction, increased with soil temperature according to the Arrhenius law, and due to a priming effect, led to the appearance of aromatic molecules. The soil-to-plant transfer of Cd and Zn was promoted at higher soil temperatures despite a parallel decrease in Cd and Zn bioavailability. This suggests that plant processes affect the soil-to-plant transfer of Cd and Zn the most when the soil temperature rises. PMID:26452657

  3. Determination of trace heavy metals (Cd, As, Pb, Zn, Cr, Cu) in some fish species from the coast of Tartous city by (AAS)

    International Nuclear Information System (INIS)

    This study deals with the concentrations of six trace heavy metals (Cd, As, Pb, Zn, Cr, Cu) in the flesh of four edible fish species including: Mugil, siganus Luridus, Siganus rivulatus and Sardine species, in addition to water samples for comparison. The samples were taken from three sites near to the sea-shore of Tartous city, on the eastern coast of the Mediterranean. The method used in this study depends on the determination of the above trace mentioned metals using (AAS) according to two techniques (Flame - AAS) and (ETA - AAS), after wet-digestion for the animal samples, and the two extraction methods (APDC - MIBK) and (APDC - CHCl3) for water samples. The study showed that the highest value was recorded in the case of Zn (29.44 μg/g, wet weight), and the lowest one was recorded in the case of Cd (0.082 μg/g, wet weight) in the flesh tissues of Mugil species. Recording standard deviation (SD), it was clear that the highest value was 1.145 μg/g for Zn, and lowest one was 0.001 μg/g for Cd in Mugil species. In order to get some information about the distribution of the studied elements, we studied the correlation coefficient. The statistical study showed a variation from a high positive relation, to low, and sometimes to negative ones. This gives a clear indication that the increasing or decreasing ratios in the concentration of the studied elements in the marine environment is related to the pollution resulting from the different sources of human activity. By comparing the results of this research with other results within and outside the Mediterranean basin, we observed a decrease in the concentration of (Cd, As, Pb, Cr, Cu) elements. and an increase in the concentration of Zn element. (Author)

  4. 赤泥对污染土壤中Cd,Pb和Zn形态及水稻生长的影响%Effects of Red Mud Addition on Fractions of Cd, Pb and Zn and Rice Growth in Contaminated Soil

    Institute of Scientific and Technical Information of China (English)

    田杰; 罗琳; 范美蓉; 魏建宏; 胡波; 刘艳

    2012-01-01

    Pot experiment was conducted in contaminated soil to investigate the effects of red mud addition on Cd, Pb and Zn fractions, uptake of Cd, Pb and Zn by rice grain and rice growth. The results showed that red mud application increased the soil pH, changed the fractions of Cd, Pb and Zn in soil, while the soil exchangeable Cd, Pb and Zn contents and the Cd, Pb and Zn contents in rice grain decreased significantly. Compared with the control, the treatment with 12.5 g red mud per 1 kg soil decreased the soil exchangeable Cd, Pb and Zn by 40.81%, 25.68% and 38.48%, while the Cd, Pb and Zn contents in rice grain decreased by 70.45%, 42.46% and 29.19%. Compared with the control, the treatment with 5.0 g red mud per 1 kg soil increased the height of rice, length of ear and grain weight per pot significantly. If the red mud addition rate was over 10.0 g per 1 kg soil, the rice growth was restrained. It is necessary to consider the amount of red mud application, as not to affect the crop growth.%通过盆栽试验,研究了赤泥对污染土壤中Cd,Pb和Zn形态和水稻糙米中Cd,Pb和Zn含量以及水稻生长的影响。结果表明,添加赤泥可有效提高土壤pH,改变土壤中Cd,Pb和Zn的形态,显著降低土壤中交换态Cd,Pb和Zn含量以及水稻糙米中的Cd,Pb和Zn含量。当赤泥施用量为12.5 g kg-1土时,土壤中交换态Cd,Pb和Zn的含量分别比空白对照降低了40.81%、25.68%和38.48%;水稻糙米中Cd,Pb和Zn的含量分别比空白对照降低了70.45%、42.46%和29.19%。与空白对照相比,赤泥施用量为5.0 g kg-1土时,水稻株高、穗长及每盆粒重均显著提高。但当赤泥施用量超过10.0 g kg-1土时水稻生长会受到抑制。在赤泥农业应用时应考虑其施用量及潜在的环境风险,以免影响作物生长。

  5. Evaluation of Exposure to Heavy Metals Cu, Zn, Cd and Pb in Vegetables Grown in the Olericultures of Zanjan Province\\'s Fields

    Directory of Open Access Journals (Sweden)

    L Tabande

    2016-06-01

    Full Text Available Background and Objective: The contamination of soils and plants with heavy metals is a serious and growing problem. The present study aimed to determine the concentration of heavy metals in soil and some agricultural products and the probability of risks due to their consumption. Materials and Methods: This cross-sectional descriptive study was performed using random sampling at harvest time in 2014 on 205 samples of vegetable crops (Leek, chard, parsley, watermelon, melon, tomatoes, cucumber, potatoes, onion, garlic, radish, green peas, and broad bean and 129 samples of soils under cultivation. Concentrations of Cu, Zn, Cd, and Pb in soil and plant samples were determined by an atomic absorption instrument and the data was analyzed using SPSS software. Results: There were significant differences between the mean concentrations of Pb, Cu, and Zn for different vegetables (P<0.001, but no significant difference was observed for Cd. The highest mean levels of Pb, Cd, Cu, and Zn were detected in parsley, chard, broad bean, and leek respectively. However, there was no heavy metal pollution in the remainder of the vegetables and soil samples (with the exception of agricultural soils adjacent to the lead mine of Mahneshan area studied. Hazard probability (HQ of each element for cancerous diseases was less than unit and the intake of heavy metals was lower than the Provisional Tolerable Daily Intake (PTDI. Conclusion: The results of this study indicated that major accumulation of heavy metals was obtained in leafy vegetables. Therefore, much attention should be paid to consumption of leafy vegetables, especially vegetables grown in the surrounding industrial areas.

  6. Nonequilibrium leaching behavior of metallic elements (Cu, Zn, As, Cd, and Pb) from soils collected from long-term abandoned mine sites.

    Science.gov (United States)

    Kim, Juhee; Hyun, Seunghun

    2015-09-01

    Leaching of metallic elements (Cu, Zn, As, Cd, and Pb) from two mine-impacted soils (DY and BS) was evaluated by batch decant-refill and seepage flow experiments. During eight consecutive leaching steps, aqueous As concentrations remained relatively constant (approx. 1.6 and 0.1 mg L(-)(1) for DY and BS, respectively), while Cu (0.01-3.2 mg L(-1)), Zn (0.2-42 mg L(-1)), and Cd (0.004-0.3 mg L(-1)) were quickly reduced. The reduction of Pb concentration (0.007-0.02 mg L(-1) and 0.2-0.9 mg L(-1) for DY and BS, respectively) was much lesser. This pattern was well-explained by the biphasic leaching model by allocating a large fast leaching fraction (ffast>0.2) for Cu, Zn, and Cd while a negligible ffast for As and Pb (impact observed for As. Element export was enhanced after flow interruption, especially under fast seepage. A transient drop in As export in slow seepage was likely due to sorption back to soil phase during the quiescent period. The ratio of Fe(2+)/Fe(3+) and SO4(2-) concentration, related to the dissolution of sulfide minerals, were also seepage rate-dependent. The results of batch and column studies imply that the leachate concentration will be enhanced by initial seepage and will be perturbed after quiescent wetting period. The conversion from kinetically leachable pool to readily leachable pool is likely responsible for nonequilibrium metal leaching from the long-term abandoned mine soils. PMID:25935604

  7. Analysis of Zn, Cd, As, Cu, Pb, and Fe in snails as bioindicators and soil samples near traffic road by ICP-OES.

    Science.gov (United States)

    Massadeh, Adnan M; Alomary, Ahmed A; Mir, Sayeeda; Momani, Fouad A; Haddad, Hazem I; Hadad, Yazen A

    2016-07-01

    Snails are used as biological indicators of the environment pollution for heavy metals. Living snail samples were collected from different sites at the city of Irbid-Jordan and classified according to their morphological features including Helix pelasga, Eobania vermiculata, Xeropicta derbentina, Oychilus, Xerocrassa seetzenii, Xerocrassa simulata, and Pila. Zn, Cd, As, Cu, Pb, and Fe levels were measured by inductively coupled plasma-optical emission spectroscopy. Results indicated that metal concentrations in all snail shell samples were with an average and range for Zn 22.4 (6.5-105.5) μg g(-1), Cd 7.8 (0.4-48.1) μg g(-1), As 25.9 (0.7-248.5) μg g(-1), Cu 15.1 (1.6-69.0) μg g(-1), Pb 0.4 (0.2-1.7) μg g(-1), and Fe 119.6 (14.0-1102.0) μg g(-1), whereas, in soil samples, the average and range for Zn 204.0 (12.0-709.0) μg g(-1), Cd 5.7 (0.2-39.5) μg g(-1), As 3.2 (1.8-5.2) μg g(-1), Cu 22.1 (2.3-77.4) μg g(-1), Pb 0.2 (0.1-0.3) μg g(-1), and Fe 242.4 (25.0-680.0) μg g(-1). PMID:27026544

  8. Experimental verification of the pKion-pH50 correlation relation in the sorbent-element (Zn, Cd, Pb) systems

    International Nuclear Information System (INIS)

    The complexing properties of polystyrene-(azo-1)-2-hydroxy-3-carboxy-5-rhodanobenzene, which is a chelating polymer sorbent, toward Zn2+, Cd2+, and Pb2+ are studied. A structure of zinc, cadmium, and lead complexes is suggested. Comparing the pKCOOH and sorption pH50 values derived experimentally with those predicted by the Hammett and KCOOH-sorption pH50 correlations confirms the power of these correlation relations to predict quantitatively the main characteristics of polychelates

  9. determination of (Cd, As, Pb, Zn, Cr, and Cu) in the flesh tissues of some kinds of marine beings at the shore of Lattakia city by AAS

    International Nuclear Information System (INIS)

    Trace heavy metals in two sort of Bivalvia and five kind of fish has been determined in comparison with water samples using atomic absorption spectroscopy method. The results showed high concentration of studied elements (Cd, As, Pb, Zn, Cr, and Cu) in the animal samples compared with the water samples and is close to the concentration of some other elements , where these concentrations reached their highest value in the Bivalvia since it has the water filtration property. Nevertheless these concentrations are still approximate with their concentrations in other parts of the Mediterranean basin and within the known limits of these elements in the marine environment. (author)

  10. Certification of trace element contents (As, Cd, Co, Cu, Fe, Mn, Hg, Na, Pb and Zn) in a fly ash obtained from the combustion of pulverised coal

    International Nuclear Information System (INIS)

    The element contents of As, Cd, Co, Cu, Fe, Mn, Hg, Na, Pb and Zn of a fly ash from pulverised coal are certified. The procedures and their results for the homogenisation, the contamination and homogeneity checks and the analytical campaign are reported. The certified mass fractions and indicative values for Cr, Ni, Th, V and water soluble sulphate are given. The work was carried out within the framework of the activities of the Community Bureau of Reference (BCR) of the Commission of the European Communities. (orig.)

  11. An Assessment of the Accumulation Potential of Pb, Zn and Cd by Avicennia marina (Forssk.) Vierh. in Vamleshwar Mangroves, Gujarat, India

    OpenAIRE

    Isaiah Nirmal KUMAR; Poliyaparambil Ravi SAJISH; Rita Nirmal KUMAR; George BASIL; Viyol SHAILENDRA

    2011-01-01

    The study deals with the accumulation of Pb, Zn and Cd in an important mangrove species, Avicennia marina (Forssk.) Vierh., in the Vamleshwar mangrove ecosystem, near Narmada estuary, West coast of Gujarat, India with height differences of 0.5, 1.5, 2.5 meters and carried out under field conditions during October, 2009. The site was located on 21�30�11.55�� N latitude and 72�43�53.68�� E longitude. Mangrove receives heavy metal pollution from upstream areas of Narmada estuary and highly popul...

  12. Efectos de la aplicación de EDTA sobre un suelo de mina contaminado por metales pesados (Pb,Zn,Cd y Cu). Riesgos asociados

    OpenAIRE

    Martín Aparicio, Alberto; Pastor Piñeiro, Jesús; Gutiérrez Maroto, Antonio; A. J. Hernández

    2005-01-01

    Se realizó un bioensayo en microcosmos con el suelo de una mina del centro peninsular contaminada por metales (Pb, Zn, Cd y Cu), a fin de evaluar el riesgo asociado a la aplicación de técnicas de fitorremediación con quelatos (EDTA) en estos casos. Se plantearon 3 situaciones: suelo sin adición de EDTA (control), suelo + 2 Tn/ha de EDTA y suelo + 4 Tn/ha de EDTA. Se midió el contenido de macroelementos y metales en el suelo y agua de lixiviación de los microcosmos, pH y materia...

  13. Bioaccumulation and damaging action of polymetal industrial dust on laboratory mice Mus musculus alba I. Analysis of Zn, Cu, Pb, and Cd disposition and mathematical model for Zn and Cd bioaccumulations

    International Nuclear Information System (INIS)

    The concentrations of Zn, Cu, Pb, and Cd in the liver, kidneys, spleen, bones, and carcass of laboratory mice BALB/cy were observed in toxicological experiments. Polymetal industrial dust containing these metals was given to experimental animals at 1% concentration mixed with conventional animal food. Samples for analyses were taken on Days 15, 40, 60, 90, and 120 posttreatment. The experimental data clearly support the established antagonistic interactions among cadmium, zinc, copper, and lead.A mathematical model was proposed to study the main tendencies of heavy metal bioaccumulation under conditions of metal interaction and excessive exposure. The experimental results were assessed on the basis of the model. A rate constant of renal excretion greater than that of hepatic excretion was obtained, which agrees with the observed inversion of cadmium kidney/liver ratio in the conditions of very high exposure

  14. CdS/CH3 NH3 PbI3共敏化 ZnO太阳能电池的光伏性能研究%Investigations on the Photovoltaic Performance of CdS/CH3 NH3 PbI3 Cosensitized ZnO Solar Cells

    Institute of Scientific and Technical Information of China (English)

    张培松; 陈红; 栾红梅; 陈钢; 庞振宇; 杨丽丽

    2015-01-01

    The quantum dots sensitized solar cells ( QDSSCs) became one of the third generation solar cells due to their lower cost and higher theoretical conversion efficiency .Cosensitization with quantum dots and organic dye was one of effective methods to improve the photoelectric conversion efficiency of QDSSCs .CH3 NH3 PbI3 perovskite was a burgeoning organic light absorption material .The CdS/CH3 NH3 PbI3 cosensitized solar cells with ZnO nanorods as photoanodes were prepared ,and the influences of cosensitization of perovskite and the deposition times of CdS quantum dots on the photovoltaic performance of solar cells were investigated .%量子点敏化太阳能电池( QDSSCs)是兼具低成本和高理论转换效率的第三代太阳能电池之一。量子点与有机染料共敏化是提高其光电转换效率的有效手段之一。CH3 NH3 PbI3钙钛矿材料是新兴的有机吸光层材料。本文将其作为共敏化剂,制作CdS/CH3 NH3 PbI3共敏化ZnO纳米棒太阳能电池,并研究CH3 NH3 PbI3钙钛矿共敏化和CdS量子点沉积次数对量子点/CH3 NH3 PbI3共敏化太阳能电池光伏性能的影响。

  15. Effect of EDTA, EDDS, NTA and citric acid on electrokinetic remediation of As, Cd, Cr, Cu, Ni, Pb and Zn contaminated dredged marine sediment.

    Science.gov (United States)

    Song, Yue; Ammami, Mohamed-Tahar; Benamar, Ahmed; Mezazigh, Salim; Wang, Huaqing

    2016-06-01

    In recent years, electrokinetic (EK) remediation method has been widely considered to remove metal pollutants from contaminated dredged sediments. Chelating agents are used as electrolyte solutions to increase metal mobility. This study aims to investigate heavy metal (HM) (As, Cd, Cr, Cu, Ni, Pb and Zn) mobility by assessing the effect of different chelating agents (ethylenediaminetetraacetic acid (EDTA), ethylenediaminedisuccinic acid (EDDS), nitrilotriacetic acid (NTA) or citric acid (CA)) in enhancing EK remediation efficiency. The results show that, for the same concentration (0.1 mol L(-1)), EDTA is more suitable to enhance removal of Ni (52.8 %), Pb (60.1 %) and Zn (34.9 %). EDDS provides effectiveness to increase Cu removal efficiency (52 %), while EDTA and EDDS have a similar enhancement removal effect on As EK remediation (30.5∼31.3 %). CA is more suitable to enhance Cd removal (40.2 %). Similar Cr removal efficiency was provided by EK remediation tests (35.6∼43.5 %). In the migration of metal-chelate complexes being directed towards the anode, metals are accumulated in the middle sections of the sediment matrix for the tests performed with EDTA, NTA and CA. But, low accumulation of metal contamination in the sediment was observed in the test using EDDS. PMID:26782321

  16. The effect of irrigation water including Cu, Pb, Cd, and Zn on the physiological and biochemical parameters in eggplant genotypes tolerant or susceptible to some abiotic stress factors

    Directory of Open Access Journals (Sweden)

    Sevinç KIRAN

    2015-12-01

    Full Text Available The eggplant genotypes (Burdur Merkez, Burdur Bucak, Kemer ve Giresun of which salt and drought tolerances were determined before by examining changes in some of the morphological and physiological characteristics were used as materials. In the studies carried out in controlled greenhouse conditions, eggplant plants were subjected to different levels heavy metal irrigation at 20 days after sowing (Control: 0 ppm; I. mixture: 0.2 ppm Cu+0.01 ppm Cd+5 ppm Pb+2 ppm Zn; II. mixture: 0.4 ppm Cu+0.02 ppm Cd+10 ppm Pb+4 ppm Zn. Young plants were harvested after forty days at heavy metal treatment and the fresh and dry shoot weight, fresh and dry root weight, shoot and root length, leaf areas, chlorophyll, malondi-aldehyde (MDA, superoxide dismutase (SOD and glutathione reductase (GR were determined. The eggplant plants were adversely affected by heavy metal applications. In parallel to increase the dose, heavy metal mixtures led to a reduction in values of fresh and dry weight of shoot and root, stem and root length, leaf area. MDA and antioxidative enzyme activities increased in plants irrigated with water containing a mixture of heavy metal. As a result of this study, tolerant Burdur Merkez and Burdur Bucak genotypes showed a better performance compared with the salt sensitive genotypes Giresun and Kemer. The plants are thought to use similar mechanisms for resistance to abiotic stresses such as drought and heavy metal stress.

  17. Assessment of the level of microelements (Pb, Cd, Zn and Ni) in milk, collected from dairy farms of polluted and non-polluted areas of Karachi, Pakistan

    International Nuclear Information System (INIS)

    An investigation was carried out for the determination of lead, cadmium, zinc and nickel in milk, collected from dairy farms of our different polluted and non-polluted areas of Karachi Pakistan. In this connection 10 milk samples were collected from each location. Milk samples collected from the polluted areas contain average maximum concentration of Pb (0.351 plus minus 0.082 ppm), Cd (0.062 plus minus 0.007 ppm), Zn (5.06 plus minus 0.177 ppm), and Ni (0.572 plus minus 0.037 ppm), where as the maximum concentration of Pb (0.105 plus minus 0.020 ppm), Cd (0.059 plus minus 0.009 ppm), Zn (4.220 plus minus 0.230 ppm) and Ni (0.328 plusminus 0.037 ppm) was found in non-polluted area. This study will be useful for the protection of any harmful effect on human with the consumption of dairy milk of Karachi, Pakistan. (author)

  18. Accumulation of Trace Metal Elements (Cu, Zn, Cd, and Pb) in Surface Sediment via Decomposed Seagrass Leaves: A Mesocosm Experiment Using Zostera marina L.

    Science.gov (United States)

    Hosokawa, Shinya; Konuma, Susumu; Nakamura, Yoshiyuki

    2016-01-01

    Accumulation of Cu, Zn, Cd, and Pb in the sediment of seagrass ecosystems was examined using mesocosm experiments containing Zostera marina (eelgrass) and reference pools. Lead was approximately 20-fold higher in the surface sediment in the eelgrass pool than in eelgrass leaves and epiphytes on the eelgrass leaves, whereas zinc and cadmium were significantly lower in the surface sediment than in the leaves, with intermediate concentrations in epiphytes. Copper concentrations were similar in both the surface sediment and leaves but significantly lower in epiphytes. Carbon and nitrogen contents increased significantly with increasing δ13C in surface sediments of both the eelgrass and reference pools. Copper, Zn, Cd, and Pb also increased significantly with increasing δ13C in the surface sediment in the eelgrass pool but not in the reference pool. By decomposition of eelgrass leaves with epiphytes, which was examined in the eelgrass pool, copper and lead concentrations increased more than 2-fold and approximately a 10-fold, whereas zinc and cadmium concentrations decreased. The high copper and lead concentrations in the surface sediment result from accumulation in decomposed, shed leaves, whereas zinc and cadmium remobilized from decomposed shed leaves but may remain at higher concentrations in the leaves than in the original sediments. The results of our mesocosm study demonstrate that whether the accumulation or remobilization of trace metals during the decomposition of seagrass leaves is trace metal dependent, and that the decomposed seagrass leaves can cause copper and lead accumulation in sediments in seagrass ecosystems. PMID:27336306

  19. Accumulation of Trace Metal Elements (Cu, Zn, Cd, and Pb in Surface Sediment via Decomposed Seagrass Leaves: A Mesocosm Experiment Using Zostera marina L.

    Directory of Open Access Journals (Sweden)

    Shinya Hosokawa

    Full Text Available Accumulation of Cu, Zn, Cd, and Pb in the sediment of seagrass ecosystems was examined using mesocosm experiments containing Zostera marina (eelgrass and reference pools. Lead was approximately 20-fold higher in the surface sediment in the eelgrass pool than in eelgrass leaves and epiphytes on the eelgrass leaves, whereas zinc and cadmium were significantly lower in the surface sediment than in the leaves, with intermediate concentrations in epiphytes. Copper concentrations were similar in both the surface sediment and leaves but significantly lower in epiphytes. Carbon and nitrogen contents increased significantly with increasing δ13C in surface sediments of both the eelgrass and reference pools. Copper, Zn, Cd, and Pb also increased significantly with increasing δ13C in the surface sediment in the eelgrass pool but not in the reference pool. By decomposition of eelgrass leaves with epiphytes, which was examined in the eelgrass pool, copper and lead concentrations increased more than 2-fold and approximately a 10-fold, whereas zinc and cadmium concentrations decreased. The high copper and lead concentrations in the surface sediment result from accumulation in decomposed, shed leaves, whereas zinc and cadmium remobilized from decomposed shed leaves but may remain at higher concentrations in the leaves than in the original sediments. The results of our mesocosm study demonstrate that whether the accumulation or remobilization of trace metals during the decomposition of seagrass leaves is trace metal dependent, and that the decomposed seagrass leaves can cause copper and lead accumulation in sediments in seagrass ecosystems.

  20. Removal of Heavy Metals Pb2+, Cu2+, Zn2+, Cd2+, Ni2+, Co2+ and Fe3+ from Aqueous Solutions by using Xanthium Pensylvanicum

    Directory of Open Access Journals (Sweden)

    Jaber SALEHZADEH

    2013-11-01

    Full Text Available The hazardous ill effects of heavy metals on the environment and public health is a matter of serious concern. Biosorption is emerging as a sustainable effective technology. Heavy metals in water resources are one of the most important environmental problems of countries. The intensification of industrial activity and environmental stress greatly contributes to the significant rise of heavy metal pollution in water resources making threats on terrestrial and aquatic life. The toxicity of metal pollution is slow and interminable, as these metal ions are non bio-degradable. The adsorption capacity of Xanthium Pensylvanicum towards metal ions such as Pb2+, Cu2+, Zn2+, Cd2+, Ni2+, Co2+ and Fe3+, was studied. The adsorption capacity was performed by batch experiments as a function of process parameters (such as sorption time and pH. Experimental results showed that the removal percentages increasing of metal ions at pH=4, initial concentration of metal ions 10 mg/L, and after 90 min of shaking was: Zn2+ < Cd2+ < Cu2+ < Pb2+ < Ni2+ < Fe3+ < Co2+.

  1. Growth of nanocrystalline thin films of metal sulfides [CdS, ZnS, CuS and PbS] at the water–oil interface

    OpenAIRE

    P. John Thomas, Gemma L. Stansfield, Nathanael Komba, David J. H. Cant, Karthik Ramasamy, Enteisar Albrasi, Hanan Al-Chaghouri, Karen L. Syres, Paul O'Brien, Wendy R. Flavell, Egid Mubofu Federica Bondino and Elena Magnano

    2015-01-01

    Simple one pot reactions between thiobiuret complexes [M(SON(CNiPr2)2)2], (M = Cd, Zn, Pb or Cu) in toluene and aqueous Na2S lead to well-defined assemblies of nanocrystals. High quality thin films of CdS, ZnS, CuS and PbS nanoparticulates adhered to the interface are produced and are transferable to glass and other substrates. The effect of reaction parameters on the nature and properties of the deposits are examined. The films are characterized by high-resolution transmission electron micro...

  2. Biomonitoring of trace metals (Cu, Cd, Cr, Hg, Pb, Zn in Mali Ston Bay (eastern Adriatic using the Mediterranean blue mussel (1998-2005

    Directory of Open Access Journals (Sweden)

    Tomislav ZVONARIĆ

    2007-06-01

    Full Text Available In Mali Ston Bay, located on the eastern Adriatic coast, mussels and oysters have traditionally been cultivated. However, previous studies showed that water and sediments from Mali Ston Bay contain elevated levels of some trace metals, which was attributed to natural processes of sedimentation and drainage. In order to assess the bioavailability of trace metals in the bay, and to assess the health risk of consumption of shellfish species from Mali Ston Bay, a passive monitoring program was carried out in the period from December 1998 to August 2005. Samples of the whole soft tissue were collected seasonally at 4 shellfish breeding farms and analyzed for essential (Cu, Zn and non-essential (Cd, Cr, THg, Pb metals. Mean concentrations of analyzed metals in the edible tissue of mussels (Cd: 1.15 mg kg-1 d.wt.; Cr: 1.65 mg kg-1 d.wt.; Cu: 5.6 mg kg-1 d.wt.; THg: 0.15 mg kg-1 d.wt.; Pb: 1.09 mg kg-1 d.wt.; Zn: 139 mg kg-1 d.wt. fell in the range of values usually found in low to moderately contaminated marine coastal areas. Examination of the spatial pattern of contaminants showed that there were no statistically significant differences among stations in Mali Ston Bay regarding trace metal content. Concentrations of Cd, Cu, Cr and THg were significantly higher during the autumn-winter period, while concentrations of Pb and Zn did not depend on the sampling season. Among six analyzed metals, only concentrations of Cd and THg were significantly negatively correlated with the condition index of the mussels. Analysis of temporal trends during the 7 years of monitoring showed that metal concentrations had not changed with time. According to EU and WHO legislation, consumption of the edible tissue of the mussels was not harmful for humans since all the values were well below the permissible limits for fresh seafood. In addition, results of the evaluation of the risks to human health associated with consumption of the mussels containing trace metals suggest

  3. Associations between standardized school performance tests and mixtures of Pb, Zn, Cd, Ni, Mn, Cu, Cr, Co, and V in community soils of New Orleans

    International Nuclear Information System (INIS)

    In New Orleans a strong inverse association was previously identified between community soil lead and 4th grade school performance. This study extends the association to zinc, cadmium, nickel, manganese, copper, chromium, cobalt, and vanadium in community soil and their comparative effects on 4th grade school performance. Adjusting for poverty, food security, racial composition, and teacher-student ratios, regression results show that soil metals variously reduce and compress student scores. Soil metals account for 22%–24% while food insecurity accounts for 29%–37% of variation in school performance. The impact on grade point averages were Ni > Co > Mn > Cu ∼Cr ∼ Cd > Zn > Pb, but metals are mixtures in soils. The quantities of soil metal mixtures vary widely across the city with the largest totals in the inner city and smallest totals in the outer city. School grade point averages are lowest where the soil metal mixtures and food insecurity are highest. - Highlights: ► Mixtures of metals vary; largest totals in the inner city and lowest in the outer city. ► An inverse association between soil Pb and 4th grade school performance is known. ► Assuming the same exposure pathway, multiple metals are compared to performance. ► Soil metals account for 22%–24% of variation in school test performance. ► Soil metal plus food insecurity accounts for 54% of explained variance. - Controlling for potential confounding variables, the accumulation of metals (Pb, Zn, Cd, Ni, Mn, Cu, Cr, and Co) in neighborhood soils is significantly negatively associated with 4th grade school performance on standardized tests in New Orleans.

  4. Atmospheric concentrations and size distributions of aircraft-sampled Cd, Cu, Pb and Zn over the southern bight of the North Sea

    Science.gov (United States)

    Injuk, J.; Otten, Ph.; Laane, R.; Maenhaut, W.; Van Grieken, R.

    In an effort to assess the atmospheric input of heavy metals to the Southern Bight of the North Sea, aircraft-based aerosol samplings in the lower troposphere were performed between September 1988 and October 1989. Total atmospheric particulate and size-differentiated concentrations of Cd, Cu, Pb and Zn were determined as a function of altitude, wind direction, air-mass history and season. The obtained data are compared with results of ship-based measurements carried out previously and with literature values of Cu, Pb and Zn, for the marine troposphere of the southern North Sea. The results point out the high variability of the concentrations with the meterological conditions, as well as with time and location. The experimentally found particle size distribution are bimodal with a significant difference in fractions of small and large particles. These large aerosol particles have a direct and essential impact on the air-to-sea transfer of anthropogenic trace metals, in spite of their low numerical abundance and relatively low heavy metal content.

  5. Chemical fractionation of Cu, Zn, Cd, Cr, and Pb in sewage sludge amended soils at the end of 65-d sorghum-sudan grass growth.

    Science.gov (United States)

    Sivapatham, Paramasivam; Lettimore, Jon M; Alva, Ashok K; Jayaraman, Kuppuswamy; Harper, Legia M

    2014-09-19

    Heavy metals are potentially toxic to human life and the environment. Metal toxicity depends on chemical associations in soil. Understanding the chemical association of trace elements in soils amended with biosolids is very important since it determines their availability within rhizosphere and mobility beyond the rhizosphere. A sequential extraction method was used to determine the various chemical associations [labile (exchangeable + sorbed), organic, carbonates, and sulfides] of Cu, Zn, Cd, Cr, and Pb at the end of sorghum-sudan grass growth (65d) in Candler fine sand (pH = 6.8) and in Ogeechee loamy sand (pH = 5.2) amended with wastewater treatment sludge (WWTS) obtained from two different sources at application rates of 0, 24.7, 49.4, 98.8, and 148.2 Mg ha(-1). Results of this study indicated that irrespective of the soil type, Cu, Cd, Cr, and Pb in the labile fractions (exchangeable + sorbed) were in the range of 0-3.0 mg kg(-1) and the amount for Zn was in the range of 0.2-6.6 mg kg(-1). Therefore, their availability to plants and mobility beyond rhizosphere would be substantially low unless further transformations occur from other fractions. Results also indicated that the presence of substantial amounts of trace elements studied were in sulfide (HNO3) fraction and in organic (NaOH) fraction irrespective of soil type with the exception of Pb which was mainly present as carbonate (Na2EDTA) fraction and the remaining Pb equally as sulfide (HNO3) and organic (NaOH) fractions. Furthermore, results indicated that Cd was mainly present as carbonate (Na2EDTA) fraction. Irrespective of soil type, source and rate of WWTS application, summation of quantities of various fractions of all the trace elements studied through sequential extraction procedure were 1 to 25 % lower than that of total recoverable quantities of these trace elements determined on acid digestion described by US EPA method 3050 B. It was further evident that growing sorghum sudan grass for 65-d

  6. Spatial and Temporal Distribution of Trace Metals (Cd, Cu, Ni, Pb, and Zn in Coastal Waters off the West Coast of Taiwan

    Directory of Open Access Journals (Sweden)

    Kuo-Tung Jiann

    2014-01-01

    Full Text Available Surface water samples were collected along the west coast of Taiwan during two expedition cruises which represent periods of different regional climatic patterns. Information on hydrochemical parameters such as salinity, nutrients, suspended particulate matter (SPM, and Chlorophyll a concentrations were obtained, and dissolved and particulate trace metal (Cd, Cu, Ni, Pb, and Zn concentrations were determined. Spatial variations were observed and the differences were attributed to (1 influence of varying extents of terrestrial inputs from the mountainous rivers of Taiwan to the coast, and (2 urbanization and industrialization in different parts of the island. Geochemical processes such as desorption (Cd and adsorption to sinking particles (Pb also contributed to the variability of trace metal distributions in coastal waters. Results showed temporal variations in chemical characteristics in coastal waters as a consequence of prevailing monsoons. During the wet season when river discharges were higher, the transport of particulate metals was elevated due to increased sediment loads. During the dry season, lower river discharges resulted in a lesser extent of estuarine dilution effect for chemicals of anthropogenic sources, indicated by higher dissolved concentrations present in coastal waters associated with slightly higher salinity.

  7. Design of Three-shell Icosahedral Matryoshka Clusters A@B12@A20 (A = Sn, Pb; B = Mg, Zn, Cd, Mn)

    Science.gov (United States)

    Huang, Xiaoming; Zhao, Jijun; Su, Yan; Chen, Zhongfang; King, R. Bruce

    2014-11-01

    We propose a series of icosahedral matryoshka clusters of A@B12@A20 (A = Sn, Pb; B = Mg, Zn, Cd), which possess large HOMO-LUMO gaps (1.29 to 1.54 eV) and low formation energies (0.06 to 0.21 eV/atom). A global minimum search using a genetic algorithm and density functional theory calculations confirms that such onion-like three-shell structures are the ground states for these A21B12 binary clusters. All of these icosahedral matryoshka clusters, including two previously found ones, i.e., [As@Ni12@As20]3- and [Sn@Cu12@Sn20]12-, follow the 108-electron rule, which originates from the high Ih symmetry and consequently the splitting of superatom orbitals of high angular momentum. More interestingly, two magnetic matryoshka clusters, i.e., Sn@Mn12@Sn20 and Pb@Mn12@Pb20, are designed, which combine a large magnetic moment of 28 µB, a moderate HOMO-LUMO gap, and weak inter-cluster interaction energy, making them ideal building blocks in novel magnetic materials and devices.

  8. Succulent species differ substantially in their tolerance and phytoextraction potential when grown in the presence of Cd, Cr, Cu, Mn, Ni, Pb, and Zn.

    Science.gov (United States)

    Zhang, Chengjun; Sale, Peter W G; Clark, Gary J; Liu, Wuxing; Doronila, Augustine I; Kolev, Spas D; Tang, Caixian

    2015-12-01

    Plants for the phytoextraction of heavy metals should have the ability to accumulate high concentrations of such metals and exhibit multiple tolerance traits to cope with adverse conditions such as coexistence of multiple heavy metals, high salinity, and drought which are the characteristics of many contaminated soils. This study compared 14 succulent species for their phytoextraction potential of Cd, Cr, Cu, Mn, Ni, Pb, and Zn. There were species variations in metal tolerance and accumulation. Among the 14 succulent species, an Australian native halophyte Carpobrotus rossii exhibited the highest relative growth rate (20.6-26.6 mg plant(-1) day(-1)) and highest tolerance index (78-93%), whilst Sedum "Autumn Joy" had the lowest relative growth rate (8.3-13.6 mg plant(-1) day(-1)), and Crassula multicava showed the lowest tolerance indices (heavy metals than other species. These findings suggest that Carpobrotus rossii is a promising candidate for phytoextraction of multiple heavy metals, and the aquatic or semiterrestrial Crassula helmsii is suitable for phytoextraction of Cd and Zn from polluted waters or wetlands. PMID:26201657

  9. Evaluation of heavy metals (Cr, Fe, Ni, Cu, Zn, Cd, Pb and Hg) in water, sediments and water lily (Eichornia crassipes) from Jose Antonio Alzate dam

    International Nuclear Information System (INIS)

    Water, sediments and water lily (Eichornia crassipes) from the Jose Antonio Alzate Dam were analyzed in order to determine concentrations of chromium, iron, nickel, copper, zinc, cadmium, lead and mercury. Mercury, lead, chromium and iron were found in concentrations above permissible limits in water, and in high concentrations in sediments. Cadmium, nickel, copper and zinc never were found in concentrations above permissible limits in water. The highest concentrations of heavy metals in water lily were found in the root. Accumulation factors decreased in the following order: Zn> Cr> Fe> Ni> Cu> Pb> Hg and Cd. Statistical differences (α < 0.5) between the collection samples dates was observed. High correlations between metals concentrations in superficial water, sediment and water hyacinth were also observed. These correlations could indicate that the heavy metals studied here, are originated from a natural source such as sediments or from an industrial source. (Author)

  10. Uncertainty-based calibration and prediction with a stormwater surface accumulation-washoff model based on coverage of sampled Zn, Cu, Pb and Cd field data

    DEFF Research Database (Denmark)

    Lindblom, Erik Ulfson; Ahlman, S.; Mikkelsen, Peter Steen

    2011-01-01

    μg/l ±80% for Pb and 0.6 μg/l ±35% for Cd. This uncertainty-based calibration procedure adequately describes the prediction uncertainty conditioned on the used model and data, but seasonal and site-to-site variation is not considered, i.e. predicting metal concentrations in stormwater runoff from...... accumulated metal available on the conceptual catchment surface. Forward Monte Carlo analysis based on the posterior parameter sets covered 95% of the observed event mean concentrations, and 95% prediction quantiles for site mean concentrations were estimated to 470 μg/l ±20% for Zn, 295 μg/l ±40% for Cu, 20...

  11. Associations between standardized school performance tests and mixtures of Pb, Zn, Cd, Ni, Mn, Cu, Cr, Co, and V in community soils of New Orleans.

    Science.gov (United States)

    Zahran, Sammy; Mielke, Howard W; Weiler, Stephan; Hempel, Lynn; Berry, Kenneth J; Gonzales, Christopher R

    2012-10-01

    In New Orleans a strong inverse association was previously identified between community soil lead and 4th grade school performance. This study extends the association to zinc, cadmium, nickel, manganese, copper, chromium, cobalt, and vanadium in community soil and their comparative effects on 4th grade school performance. Adjusting for poverty, food security, racial composition, and teacher-student ratios, regression results show that soil metals variously reduce and compress student scores. Soil metals account for 22%-24% while food insecurity accounts for 29%-37% of variation in school performance. The impact on grade point averages were Ni > Co > Mn > Cu ~ Cr ~ Cd > Zn > Pb, but metals are mixtures in soils. The quantities of soil metal mixtures vary widely across the city with the largest totals in the inner city and smallest totals in the outer city. School grade point averages are lowest where the soil metal mixtures and food insecurity are highest. PMID:22705504

  12. Determination of Cu, Zn, Pb and Cd by Atomic Emission Spectrometry with Inductively Coupled Plasma in Organs of the Specie Gambusia punctata (Poeciliidae)

    International Nuclear Information System (INIS)

    The aim of this research was to adequate the ICP-AES method to the quantification of Cu, Zn, Pb and Cd in brain, liver and gills of the specie Gambusia punctata, in order to know the level of exposure of the ecosystems San Juan and File in Santiago de Cuba province. To achieve the fitness for purpose of the method, limits of detection, reproducibility and accuracy were evaluated using reference certificated materials of fishes. The biological samples were classified according the ecosystem, length, sex and organ. It were dried, digested with mix of acids and the metals measured in the spectrometer. The results demonstrated that factors as length and sex have not influence in the bioaccumulation, whereas the gill was the organ where all the elements were bioaccumulated. Finally, due that the smallest concentrations of metals were in the File ecosystem, it could be used as an environmental reference

  13. Time saving modified BCR sequential extraction procedure for the fraction of Cd, Cr, Cu, Ni, Pb and Zn in sediment samples of polluted lake

    International Nuclear Information System (INIS)

    The mobility, availability and persistence of heavy metals (Cd, Cr, Cu, Ni, Pb and Zn) in contaminated lake sediment samples were evaluated by means of sequential extraction scheme, proposed by the Community Bureau of Reference protocol (BCR). The metal content in the extracts was measured by atomic absorption spectrometry. The precision and accuracy of the proposed procedure were evaluated by using a certified reference material BCR 701. The maximum recoveries for heavy metals (HMs) were observed for all three steps of BCR protocol at 32 h total shaking period instead of previously reported 51 h, with p > 0.05. The lixiviation tests (DIN 38414-S4) were used to evaluate the leaching of HMs from sediment samples and it was observed that levels of water extractable HMs were low as compared to those values obtained by acid-soluble fraction of the BCR protocol

  14. Concentración de metales pesados (Cu, Ni, Zn, Cd, Pb) en la biota y sedimentos de una playa artificial, en la bahía San Jorge 23°S, norte de Chile Heavy metals concentration (Cu, Ni, Zn, Cd, Pb), in biota and sediments of an artificial beach, in San Jorge bay 23°S, northern Chile

    OpenAIRE

    Gabriel Castro; Jorge Valdés

    2012-01-01

    Se evaluó el contenido de metales pesados (Cu, Ni, Zn, Cd, Pb) en la biota y el sedimento de una playa artificial (Paraíso) y una playa natural (El Lenguado), ubicadas en la bahía San Jorge, norte de Chile. Los resultados fueron utilizados para comparar ambos sistemas, el grado de cumplimiento de la normativa ambiental nacional e internacional, y el efecto de la construcción de la playa artificial sobre el nivel de contaminación por metales existentes históricamente en esa zona. En cada playa...

  15. An investigation of the evolution of evolution of distribution and accumulation of heavy metals(Cr, Ni, Cu, Cd, Zn and Pb) in Anzali wetland's sediments

    International Nuclear Information System (INIS)

    To investigate the precipitation of heavy metals in Anzali wetland and evaluate its refining performance this study was carried out on the wetland. Monthly samples of sediments from 15 stations including inlets, outlets and some internal locations in the wetland were collected and analyzed over a period of six months (July - December 2002). Sediment samples were analyzed for six metals of Cr, Cd, Pb, Zn, Cu and Ni. Wet digestion method was employed for extraction of metals in samples by and through a solution containing HN03 and HCL. Atomic Adsorption spectrophotometry was employed for measurement of the heavy metals. Statistical methods, including analysis of variance (ANOVA), correlation and Cluster analysis were used for analysis of the data. The results indicated that concentration of heavy metals present in sediments (collected from different stations and at different times) here significantly different. Among the metals studied, Zn was of the highest concentration Heavy metal concentrations in stations 1 1, 12 and 13 were lower than in other stations. Sediments in station 5 contained the highest concentrations of heavy metals among all sediments. It can be stated that concentration of heavy metals decreases with an increase in the distance from delta of rivers entering the wetland.2. This is due to the role and performance of wetland chemical contents in reduction of pollutants, the self-purification action of wetland as well as precipitation of heavy metals at the beginning of the entries into the wetland

  16. Environmental behaviors and potential ecological risks of heavy metals (Cd, Cr, Cu, Pb, and Zn) in multimedia in an oilfield in China.

    Science.gov (United States)

    Hu, Yan; Wang, Dazhou; Li, Yu

    2016-07-01

    The environmental behaviors of five heavy metals (Cd, Cr, Cu, Pb, and Zn) in a Chinese oilfield were investigated using a steady-state multimedia aquivalence (SMA) model. The modeling results showed good agreement with the actual measured values, with average residual errors of 0.69, 0.83, 0.35, 0.16, and 0.54 logarithmic units for air, water, soil, sediment, and vegetation compartments, respectively. Model results indicated that most heavy metals were buried in sediment, and that transfers between adjacent compartments were mainly deposition from the water to the sediment compartment (48.59 %) and from the air to the soil compartment (47.74 %) via atmospheric dry/wet deposition. Sediment and soil were the dominant sinks, accounting for 68.80 and 25.26 % of all the heavy metals in the multimedia system, respectively. The potential ecological risks from the five heavy metals in the sediment and soil compartments were assessed by the potential ecological risk index (PERI). The assessment results demonstrate that the heavy metals presented low levels of ecological risk in the sediment compartment, and that Cd was the most significant contributor to the integrated potential ecological risk in the oilfield. The SMA model provided useful simulations of the transport and fate of heavy metals and is a useful tool for ecological risk assessment and contaminated site management. PMID:27040543

  17. Speciation and fractionation of heavy metals in soil experimentally contaminated with Pb, Cd, Cu and Zn together and effects on soil negative surface charge

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Speciation of heavy metals in soil subsamplesexperimentally loaded with Pb, Cd, Cu and Zn in orthogonal designwas investigated by sequential extraction, and operationallydefined as water-soluble and exchangeable(SE), weakly specificadsorbed(WSA), Fe and Mn oxides-bound(OX) and organic-bound(ORG).The results show that speciation of heavy metals in the soilsubsamples depended on their kinds. About 90% of Cd and 75% of Znexisted in soil subsamples in the SE fraction. Lead and Cu existedin soil subsamples as SE, WSA and OX fractions simultaneously,although SE was still the major fraction. Organic-bound heavymetals were not clearly apparent in all the soil subsamples. Theconcentration of some heavy metal speciation in soil subsamplesshowed good correlation with ionic impulsion of soil, especiallyfor the SE fraction. Continuous saturation of soil subsamples with0.20 mol/L NH4Cl, which is the first step for determination of thenegative surface charge of soil by the ion retention method, resulted in desorption of certain heavy metals from the soil. Itwas found that the percentage desorption of heavy metals from soilsubsamples depended greatly on pH, the composition and originalheavy metal content of the soil subsamples. However, most of theheavy metals in the soil subsamples were still retained aftermultiple saturation. Compared with the parent soil, the negativesurface charge of soil subsamples loaded with heavy metals did notshow differ significantly from that of the parent one bystatistical analysis. Heavy metals existed in the soil subsamplesmainly as exchangeable and precipitated simultaneously.

  18. Study on the distributions of Cd, Co, Sr, Zn, Ag, Cu, Pb, Mn and Ni in the eolian sands of the Gavkuni playa (southeast of Isfahan

    Directory of Open Access Journals (Sweden)

    Hamidreza Pakzad

    2014-11-01

    Full Text Available Introduction Heavy metals are continually introduced into hydrosphere, atmosphere and biosphere. These potentially toxic elements can concentrate in sediments in aqueous ecosystems and they can act as pollution sources in particular conditions. Heavy metals mainly concentrate in fine sand particles because of more concentration of heavy minerals in this grain size. The Gavkhuni playa lake with an approximate area of 550 km2 is located at southeast of Isfahan, Iran. The Zayandehrud permanent river and several seasonal rivers flow into this playa. During quaternary, massive volume of sediments in sand and gravel sizes were carried into this area and deposited. These sediments are mainly deposited in the delta of Zayandehrud river (northwest of Gavkhuni playa and northwest of the sand dunes in margin of the Zayandehrud river particularly from Varzaneh to the playa. The megafans surrounding the playa can be partly origin of these sediments. The Gavkhuni playa lake is composed of three major flats namely sand, mud and salt flats. The salt flat forms the major part of the playa. Igneous, metamorphic and sedimentary (mainly carbonates rocks outcrop in the drainage basin of the Gavkhuni playa lake. Schist, gneiss, limestone, shale and andesite are the dominant lithology in this basin. The main objective of this research is to determine the concentrations of Cd, Co, Sr, Zn, Ag, Cu, Pb, Mn and Ni in the eolian sand deposits, the factors influencing the distributions of these elements and also relationship between the heavy metals and the minerals (particularly heavy minerals containing these elements. Material & Methods The eolian sands (sand dunes and sand flats of the Gavkhuni playa were sampled in 15 sampling points from north to south of the playa. Grain size distribution of the sediments were determined through dry sieving method. Heavy minerals were separated and studied through microscopy of the prepared thin and polish sections. The concentration

  19. A comparison of Cu, Pb, As, Cd, Zn, Fe, Ni and Mn determined by acid extraction/ICP-OES and ex situ field portable X-ray fluorescence analyses

    International Nuclear Information System (INIS)

    Total concentrations of Cu, Pb, As, Cd, Zn, Fe, Ni and Mn were determined for 81 soil samples using two types of field portable X-ray fluorescence (FPXRF) system; dual isotope and X-ray tube. FPXRF metal concentrations were statistically compared with analytical results from aqua regia extractions followed by Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES) analysis. The ability of each FPXRF instrument to produce analytical results comparable to the reference method was assessed by linear regression. A high degree of linearity was found for Fe and Pb with the X-ray tube instrument and for Fe, Cu, Pb, Zn, Cd and Mn with the dual source instrument. FPXRF analyser performance improved with increased analysis time for Cu, Mn and Pb, whilst Fe, Zn, Cd, Ni and As showed no significant improvement. Particle size did not influence FPXRF analyser performance. Both the dual isotope and the X-ray tube FPXRF instruments are effective tools for rapid, quantitative assessment of soil metal contamination and for monitoring the efficacy of remediation strategies. - Portable X-ray fluorescence instruments can provide an accurate, rapid and cost-effective means of assessing soil contamination and for monitoring the efficacy of remediation strategies

  20. Nuclear and related analytical methods applied to the determination of Cr, Ni, Cu, Zn, Cd and Pb in a red ferralitic soil and Sorghum samples

    International Nuclear Information System (INIS)

    Several studies on the influence of heavy metals to the growth of vegetables have been carried out in Cuba by the Ministry of Agriculture in order to evaluate the effects resulting of the continuous application of fertilizers and other materials to the soils. The analysis of metal contents in soil and vegetable samples is often troublesome due to the low concentration levels to be determined. In the present work EDXRF, AAS and ASV methods were applied and compared for the evaluation of Cr, Ni, Cu, Zn, Cd and Pb contents in red ferralitic soil and Sorghum samples. Several certified reference materials (CRM) (inorganic and organic matrixes) were analyzed in order to evaluate the performance of the analytical procedures and the bias and precision of the results. A study was performed with growing Sorghum in several series of pots where different quantities of metals were added to the soil substrate. The observed correlation between the metal contents in soil and plants as well as the influence of different additions of each metal on the plant growth is also presented. (author)

  1. The Uptake Mechanism of Cd(II, Cr(VI, Cu(II, Pb(II, and Zn(II by Mycelia and Fruiting Bodies of Galerina vittiformis

    Directory of Open Access Journals (Sweden)

    Dilna Damodaran

    2013-01-01

    Full Text Available Optimum concentrations of heavy metals like copper, cadmium, lead, chromium, and zinc in soil are essential in carrying out various cellular activities in minimum concentrations and hence help in sustaining all life forms, although higher concentration of these metals is lethal to most of the life forms. Galerina vittiformis, a macrofungus, was found to accumulate these heavy metals into its fleshy fruiting body in the order Pb(II > Cd(II > Cu(II > Zn(II > Cr(VI from 50 mg/kg soil. It possesses various ranges of potential cellular mechanisms that may be involved in detoxification of heavy metals and thus increases its tolerance to heavy metal stress, mainly by producing organic acids and phytochelatins (PCs. These components help in repairing stress damaged proteins and compartmentalisation of metals to vacuoles. The stress tolerance mechanism can be deduced by various analytical tools like SEM-EDX, FTIR, and LC-MS. Production of two kinds of phytochelatins was observed in the organism in response to metal stress.

  2. The Uptake Mechanism of Cd(II), Cr(VI), Cu(II), Pb(II), and Zn(II) by Mycelia and Fruiting Bodies of Galerina vittiformis

    Science.gov (United States)

    Damodaran, Dilna; Balakrishnan, Raj Mohan; Shetty, Vidya K.

    2013-01-01

    Optimum concentrations of heavy metals like copper, cadmium, lead, chromium, and zinc in soil are essential in carrying out various cellular activities in minimum concentrations and hence help in sustaining all life forms, although higher concentration of these metals is lethal to most of the life forms. Galerina vittiformis, a macrofungus, was found to accumulate these heavy metals into its fleshy fruiting body in the order Pb(II) > Cd(II) > Cu(II) > Zn(II) > Cr(VI) from 50 mg/kg soil. It possesses various ranges of potential cellular mechanisms that may be involved in detoxification of heavy metals and thus increases its tolerance to heavy metal stress, mainly by producing organic acids and phytochelatins (PCs). These components help in repairing stress damaged proteins and compartmentalisation of metals to vacuoles. The stress tolerance mechanism can be deduced by various analytical tools like SEM-EDX, FTIR, and LC-MS. Production of two kinds of phytochelatins was observed in the organism in response to metal stress. PMID:24455671

  3. The Survey and Measurement of Ni, Pb, Cu, Mn, Zn, Cd and V Content in Green Vegetables of South Area of Tehran Refinery

    International Nuclear Information System (INIS)

    Oil pollution is one of the most critical soil and water pollutant. Areas which are subjected to oil industry may have this kind of pollution by different ways such as extraction, transformation and refining. The example of these areas is south east of Tehran refinery which is surrounded by agricultural fields and are subjected by pollution via Tehran refinery, oil transforming lines, waste water and industrial activities. Since the crops from this area is providing the needs of neighbor cities like Tehran, to realize their oil pollution, the content of some heavy metals like Ni, V, Cu, Cd, Zn, Pb and Mn has been measured. The results analyzed by analytical method include SPSS and MVSP. Finally the relation between elements and pollution has been recognized. The result of this survey showed the high heavy metal content in most plants which were higher than similar research. Onion had the highest amount of most heavy metals. Ni and Pd content were high in plants which are indicator of oil pollution.

  4. Removal of Cd(II), Zn(II) and Pb(II) from aqueous solutions by brown marine macro algae: Kinetic modelling

    Energy Technology Data Exchange (ETDEWEB)

    Freitas, Olga M.M. [LRSE - Laboratory of Separation and Reaction Engineering, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias 4200-465 Porto (Portugal); REQUIMTE, Instituto Superior de Engenharia do Porto, Rua Dr. Bernardino de Almeida 431 4200-072 Porto (Portugal); Martins, Ramiro J.E. [Departamento de Engenharia Quimica e Biologica, Escola Superior de Tecnologia, Instituto Politecnico de Braganca, Campus de Santa Apolonia, 5301-857 Braganca (Portugal); LRSE - Laboratory of Separation and Reaction Engineering, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias 4200-465 Porto (Portugal); Delerue-Matos, Cristina M. [REQUIMTE, Instituto Superior de Engenharia do Porto, Rua Dr. Bernardino de Almeida 431 4200-072 Porto (Portugal); Boaventura, Rui A.R. [Departamento de Engenharia Quimica, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto (Portugal); LRSE - Laboratory of Separation and Reaction Engineering, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias 4200-465 Porto (Portugal)], E-mail: bventura@fe.up.pt

    2008-05-01

    Specific marine macro algae species abundant at the Portuguese coast (Laminaria hyperborea, Bifurcaria bifurcata, Sargassum muticum and Fucus spiralis) were shown to be effective for removing toxic metals (Cd(II), Zn(II) and Pb(II)) from aqueous solutions. The initial metal concentrations in solution were about 75-100 mg L{sup -1}. The observed biosorption capacities for cadmium, zinc and lead ions were in the ranges of 23.9-39.5, 18.6-32.0 and 32.3-50.4 mg g{sup -1}, respectively. Kinetic studies revealed that the metal uptake rate was rather fast, with 75% of the total amount occurring in the first 10 min for all algal species. Experimental data were well fitted by a pseudo-second order rate equation. The contribution of internal diffusion mechanism was significant only to the initial biosorption stage. Results indicate that all the studied macro algae species can provide an efficient and cost-effective technology for eliminating heavy metals from industrial effluents.

  5. Selective removal of Pb(II), Cd(II), and Zn(II) ions from waters by an inorganic exchanger Zr(HPO3S)2

    International Nuclear Information System (INIS)

    The present study reported synthesis of a new inorganic exchanger, i.e., zirconium hydrogen monothiophosphate [Zr(HPO3S)2, denoted ZrPS] and its selective sorption toward Pb(II), Cd(II) and Zn(II) ions. ZrPS sorption toward all the three metals is dependent upon solution pH due to the ion-exchange nature. As compared to another inorganic exchanger zirconium phosphate [Zr(HPO4)2, denoted ZrP], ZrPS exhibits highly selective sorption toward these toxic metals from the background of calcium ions at great levels. Such sorption preference is mainly attributed to the presence of -SH group in ZrPS, as further demonstrated by FT-IR analysis and XPS study. Moreover, ZrPS particles preloaded with heavy metals could be efficiently regenerated with 6 M HCl for multiple use without any noticeable capacity loss. All the experimental results indicated that ZrPS is a promising sorbent for enhanced heavy metals removal from contaminated water.

  6. Influence of fly ash aided phytostabilisation of Pb, Cd and Zn highly contaminated soils on Lolium perenne and Trifolium repens metal transfer and physiological stress

    International Nuclear Information System (INIS)

    Due to anthropogenic activities, large extends of soils are highly contaminated by Metal Trace Element (MTE). Aided phytostabilisation aims to establish a vegetation cover in order to promote in situ immobilisation of trace elements by combining the use of metal-tolerant plants and inexpensive mineral or organic soil amendments. Eight years after Coal Fly Ash (CFA) soil amendment, MTE bioavailability and uptake by two plants, Lolium perenne and Trifolium repens, were evaluated, as some biological markers reflecting physiological stress. Results showed that the two plant species under study were suitable to reduce the mobility and the availability of these elements. Moreover, the plant growth was better on CFA amended MTE-contaminated soils, and the plant sensitivity to MTE-induced physiological stress, as studied through photosynthetic pigment contents and oxidative damage was lower or similar. In conclusion, these results supported the usefulness of aided phytostabilisation of MTE-highly contaminated soils. - Highlights: → Aided phytostabilisation aims to establish a vegetation cover in order to promote immobilisation of MTE. → 8 years after the soil amendments, a pot culture study was carried out in greenhouse conditions. → MTE bioavailability and uptake by the two plants was drastically decreased with amendments. → Our results support the usefulness of aided phytostabilisation of MTE-highly contaminated soils. → CFA addition contributed to the reduction of the MTE mobility and availability for the plants. - Efficiency of Coal Fly Ash amendment for phytostabilisation of Pb, Cd and Zn in MTE-highly contaminated soils.

  7. Environmental impact of the former Pb-Zn mining and smelting in East-Belgium.

    OpenAIRE

    Cappuyns, Valérie; Swennen, Rudy; Vandamme, A.; Niclaes, M

    2005-01-01

    In the mining district of Plombières-La Calamine (East-Belgium), extensive Pb-Zn mining activities resulted in an important contamination of overbank sediments along the Geul river. Moreover, a huge amount of heavy metals is stored in a dredged mine pond tailing, which is located along the river. In the dredged mine pond tailing sediments, Pb-Zn minerals control the solubility of Zn, Pb and Cd. Although Pb, Zn and Cd display a lower solubility in overbank sediments compared to the mine tailin...

  8. Ultrafine particle and fine trace metal (As, Cd, Cu, Pb and Zn) pollution episodes induced by industrial emissions in Huelva, SW Spain

    Science.gov (United States)

    Fernández-Camacho, R.; Rodríguez, S.; de la Rosa, J.; Sánchez de la Campa, A. M.; Alastuey, A.; Querol, X.; González-Castanedo, Y.; Garcia-Orellana, I.; Nava, S.

    2012-12-01

    Urban air quality impairment by ultrafine particles has become a matter of concern due to the adverse effects on human health. Most of the studies of ultrafine particles in urban air quality have focused on vehicle exhaust emissions. We studied how industrial emissions contribute to ultrafine particle concentrations in downwind urban ambient air. This research is based on experimental data collected in the ambient air of the industrial city of Huelva (SW Spain) over April 2008-December 2009 period (particle number, gaseous pollutants and black carbon concentrations and levels and chemical composition of PM10 and PM2.5 with daily and hourly resolution). This city is affected by emissions from the second largest Cu-smelter in Europe, phosphoric acid and fertilizer production plants and an oil refinery and petrochemical plant. Industrial emissions are the main cause of ultrafine particle episodes. When vehicle exhaust emissions are the main source, ultrafine particles typically show (24-h mean) concentrations within the range 14,700-5000 cm-3 (50th-1st), with 60% of these linked to this source and 30% to industrial emissions. In contrast, when daily mean levels of N are within the range 50,000-25,500 cm-3 (100th-70th), industrial and vehicle exhaust emissions accounted for 49 and 30%, respectively. High concentrations of toxic trace metals (As, Cu, Cd, Zn and Pb) were recorded when the study city suffered fumigations of the Cu-smelter plumes (e.g. 10-25 ng m-3 As, 1-2 ng m-3 Cd and >105 cm-3 of ultrafine particles). Because of these industrial emissions, ultrafine particle concentrations during daylight are about two times higher than those observed in other European cities. Recently, ultrafine particle emissions in vehicle exhausts have been subject to limit values in a recent stage of the EURO standards. Industrial emissions should also be considered.

  9. Effects of heavy metal concentrations (Cd, Zn and Pb) in agricultural soils near different emission sources on quality, accumulation and food safety in soybean [Glycine max (L.) Merrill

    Energy Technology Data Exchange (ETDEWEB)

    Salazar, Maria Julieta [Multidisciplinary Institute of Plant Biology, Pollution and Bioindicator Section, Faculty of Physical and Natural Sciences, National University of Cordoba, Av. Velez Sarsfield 1611, X5016CGA Cordoba (Argentina); Rodriguez, Judith Hebelen, E-mail: jrodriguez@com.uncor.edu [Multidisciplinary Institute of Plant Biology, Pollution and Bioindicator Section, Faculty of Physical and Natural Sciences, National University of Cordoba, Av. Velez Sarsfield 1611, X5016CGA Cordoba (Argentina); Nieto, Gaston Leonardo; Pignata, Maria Luisa [Multidisciplinary Institute of Plant Biology, Pollution and Bioindicator Section, Faculty of Physical and Natural Sciences, National University of Cordoba, Av. Velez Sarsfield 1611, X5016CGA Cordoba (Argentina)

    2012-09-30

    Highlights: Black-Right-Pointing-Pointer Soybean grown near metal sources presents a toxicological hazard from heavy metals for Chinese consumers. Black-Right-Pointing-Pointer Rhizosphere soil is the most suitable compartment for toxicological studies. Black-Right-Pointing-Pointer Soil guidelines should be modified considering the exchangeable metals. - Abstract: Argentina is one of the major producers of soybean in the world, this generates a high global demand for this crop leading to find it everywhere, even close to human activities involving pollutant emissions. This study evaluated heavy metal content, the transfer of metals and its relation to crop quality, and the toxicological risk of seed consumption, through soil and soybean sampling. The results show that concentrations of Pb and Cd in soils and soybeans at several sites were above the maximum permissible levels. The heavy metal bioaccumulation depending on the rhizosphere soil compartment showed significant and high regression coefficients. In addition, the similar behavior of Cd and Zn accumulation by plants reinforces the theory of other studies indicating that these metals are incorporated into the plant for a common system of transport. On the other hand, the seed quality parameters did not show a clear pattern of response to metal bioacumulation. Taken together, our results show that soybeans grown nearby to anthropic emission sources might represent a toxicological hazard for human consumption in a potential Chinese consumer. Hence, further studies should be carried out taking into account the potential negative health effects from the consumption of soybeans (direct or indirect through consumption of meat from cattle) in these conditions.

  10. Qualitative analysis of As, Ba, Cd, Cr, Zn, Fe, Mn, K, Hg, Pb y Cu, as constituents of Amatitlan Lake sediment by XRF

    International Nuclear Information System (INIS)

    Samples of fifteen sampling points were analyzed. Molybdenum X-ray tube with secondary excitation assembly, SiLi detector and deconvolution software AXIL were employed; self-standardization method based upon incoherent ratio was used for quantitative analysis of some elements. Ca, P, S, Ti, Mn, Fe, Cr, Zn, Cu, Ni, Ga, As, Pb, Ge, Sr and Pb, were found. As, Pb and Cu concentrations lower than 109 mg/lt, 119 mg/lt, and 500mg/lt, respectively, were measured. Hg was not detected. (author)

  11. Long-term environmental exposure to metals (Cu, Cd, Pb, Zn) activates the immune cell stress response in the common European sea star (Asterias rubens).

    Science.gov (United States)

    Matranga, V; Pinsino, A; Randazzo, D; Giallongo, A; Dubois, P

    2012-05-01

    The common sea star Asterias rubens represents a key-species of the North-Eastern Atlantic macro benthic community. The cells of their immune system, known as coelomocytes, are the first line of defence against environmental hazards. Here, we report the results of investigations on the immune cells response of sea stars exposed to marine environmental pollution for long periods. We show that levels of the heat shock cognate protein 70 (HSC70) in coelomocytes from A. rubens, which were collected during a field study in the Sǿrfjord (North Sea, SW coast of Norway) along a contamination gradient, are directly associated with the long-term accumulation of Cd, Cu heavy metals exclusively in the tegument. Conversely, Pb and Zn accumulation in the tegument did not relate to HSC70 levels and none of the metals were found accumulated in the pyloric coeca. In addition the coelomocytes from A. rubens, collected in high and low metal impacted stations were examined by a proteomic approach using two-dimensional electrophoresis (2DE). By comparison of the proteomic maps, we observed that 31 protein spots differed in their relative abundance, indicating a gene expression response to the metal mixture exposure. All together, our results confirm that the echinoderm immune cells are a suitable model for the assessment of long-term exposure to environmental pollution, moreover that the increased level of HSC70 can be considered a signal of an acquired tolerance within a large spectrum of protein profile changes occurring in response to metal contamination. PMID:22000270

  12. Dissolved and labile concentrations of Cd, Cu, Pb, and Zn in the South Fork Coeur d'Alene River, Idaho: Comparisons among chemical equilibrium models and implications for biotic ligand models

    Science.gov (United States)

    Balistrieri, L.S.; Blank, R.G.

    2008-01-01

    In order to evaluate thermodynamic speciation calculations inherent in biotic ligand models, the speciation of dissolved Cd, Cu, Pb, and Zn in aquatic systems influenced by historical mining activities is examined using equilibrium computer models and the diffusive gradients in thin films (DGT) technique. Several metal/organic-matter complexation models, including WHAM VI, NICA-Donnan, and Stockholm Humic model (SHM), are used in combination with inorganic speciation models to calculate the thermodynamic speciation of dissolved metals and concentrations of metal associated with biotic ligands (e.g., fish gills). Maximum dynamic metal concentrations, determined from total dissolved metal concentrations and thermodynamic speciation calculations, are compared with labile metal concentrations measured by DGT to assess which metal/organic-matter complexation model best describes metal speciation and, thereby, biotic ligand speciation, in the studied systems. Results indicate that the choice of model that defines metal/organic-matter interactions does not affect calculated concentrations of Cd and Zn associated with biotic ligands for geochemical conditions in the study area, whereas concentrations of Cu and Pb associated with biotic ligands depend on whether the speciation calculations use WHAM VI, NICA-Donnan, or SHM. Agreement between labile metal concentrations and dynamic metal concentrations occurs when WHAM VI is used to calculate Cu speciation and SHM is used to calculate Pb speciation. Additional work in systems that contain wide ranges in concentrations of multiple metals should incorporate analytical speciation methods, such as DGT, to constrain the speciation component of biotic ligand models. ?? 2008 Elsevier Ltd.

  13. Determination of trace Cd, Cu, Fe, Pb and Zn in diesel and gasoline by inductively coupled plasma mass spectrometry after sample clean up with hollow fiber solid phase microextraction system

    International Nuclear Information System (INIS)

    This study reports a simple and efficient method for the determination of trace Cd, Cu, Fe, Pb and Zn in diesel and gasoline samples by inductively coupled plasma mass spectrometry after matrix removal and analyte pre-concentration using hollow fiber-solid phase microextraction (HF–SPME). The optimization of HF-SPME procedure was carried out using two-level full factorial and central composite designs. Four factors (variables), that are, sample solution pH, acceptor phase amount, extraction time and eluent concentration were optimized. Under the optimized experimental conditions, the precision was ≤ 3% (C = 10 μg L−1, n = 15), limits of detection and quantification ranged from 0.1 to 0.3 μg L−1 and 0.3–0.9 μg L−1, respectively, and the maximum preconcentration factor was 30. The HF-SPME method was applied for the determination of trace metals in real gasoline and diesel samples. - Highlights: • Hollow fiber solid phase microextraction of metal ions in diesel and gasoline • Use of hollow fiber-supported sol–gel combined with cation exchange resin • Optimization of HF-SPME using multivariate techniques • Determination of Cd, Cu, Fe, Pb and Zn using ICP–MS • Relatively low LOD and LOQ

  14. Avoidance Reaction of Penaeus Chinensis to Heavy Metals (Pb, Cr,Zn) and Heavy Metal Mixtures (Pb-Cr, Pb-Zn)

    Institute of Scientific and Technical Information of China (English)

    陈民山

    2001-01-01

    Study on the avoidance response of Penaeus chinensis to heavy metals (Pb, Cr, Zn) and heavy metal mixtures (Pb-Cr, Pb-Zn) is carred out using a Y-model avoidance apparatus. The concentrations calculated to induce 50% avoidance rate byPenaeus chinensis are 11.4, 33.2 and 238. 1 mg/L for Pb, Cr and Zn, respectively. Mixtures of Pb-Cr and Pb-Zn produce additive effect in the avoidance test using Penaeus chinesis. But when the mixed Pb-Zn solution has 0.5 toxic unit Pb and 0.5 toxic unit Zn, the mixture seems to have synergistic effect.

  15. Concentración de metales pesados (Cu, Ni, Zn, Cd, Pb en la biota y sedimentos de una playa artificial, en la bahía San Jorge 23°S, norte de Chile Heavy metals concentration (Cu, Ni, Zn, Cd, Pb, in biota and sediments of an artificial beach, in San Jorge bay 23°S, northern Chile

    Directory of Open Access Journals (Sweden)

    Gabriel Castro

    2012-07-01

    Full Text Available Se evaluó el contenido de metales pesados (Cu, Ni, Zn, Cd, Pb en la biota y el sedimento de una playa artificial (Paraíso y una playa natural (El Lenguado, ubicadas en la bahía San Jorge, norte de Chile. Los resultados fueron utilizados para comparar ambos sistemas, el grado de cumplimiento de la normativa ambiental nacional e internacional, y el efecto de la construcción de la playa artificial sobre el nivel de contaminación por metales existentes históricamente en esa zona. En cada playa se ubicaron estaciones equidistantes que abarcaron desde el intermareal hasta el submareal de las cuales fueron extraídos los organismos. Se tomaron muestras de sedimento en cada playa y se determinaron las pendientes con el método de Emery. El análisis granulométrico evidenció el predominio de arena media en playa El Lenguado, y arena media y fina en playa Paraíso. El contenido de materia orgánica fue mayor en El Lenguado. En playa Paraíso se determinaron cinco phylum/superclase agrupados en 19 taxa, mientras que en El Lenguado se encontraron cuatro phylum/superclase agrupados en cc taxa. El contenido de metales en sedimentos y en la mayoría de organismos presentó valores mayores en playa Paraíso. Estos resultados, junto a las normas de calidad chilenas y norteamericanas, sugieren un evidente deterioro en la calidad ambiental de playa Paraíso lo que se demostró por un incremento en las concentraciones de estos metales desde su construcción, los que sobrepasan los límites establecidos por ambas normas.It was evaluated the heavy metal content (Cu, Ni, Zn, Cd, Pb in biota and sediment of an artificial beach (Paraíso and a natural beach (El Lenguado, both located in San Jorge bay, northern Chile. The results were used to compare both systems, the degree of fulfillment of national and international environmental regulations, and the effect of the construction of the artificial beach on the level of metal contamination historically existing in

  16. A transferable force field for CdS-CdSe-PbS-PbSe solid systems

    International Nuclear Information System (INIS)

    A transferable force field for the PbSe-CdSe solid system using the partially charged rigid ion model has been successfully developed and was used to study the cation exchange in PbSe-CdSe heteronanocrystals [A. O. Yalcin et al., “Atomic resolution monitoring of cation exchange in CdSe-PbSe heteronanocrystals during epitaxial solid-solid-vapor growth,” Nano Lett. 14, 3661–3667 (2014)]. In this work, we extend this force field by including another two important binary semiconductors, PbS and CdS, and provide detailed information on the validation of this force field. The parameterization combines Bader charge analysis, empirical fitting, and ab initio energy surface fitting. When compared with experimental data and density functional theory calculations, it is shown that a wide range of physical properties of bulk PbS, PbSe, CdS, CdSe, and their mixed phases can be accurately reproduced using this force field. The choice of functional forms and parameterization strategy is demonstrated to be rational and effective. This transferable force field can be used in various studies on II-VI and IV-VI semiconductor materials consisting of CdS, CdSe, PbS, and PbSe. Here, we demonstrate the applicability of the force field model by molecular dynamics simulations whereby transformations are initiated by cation exchange

  17. Responses of different water spinach cultivars and their hybrid to Cd, Pb and Cd-Pb exposures.

    Science.gov (United States)

    Xin, Junliang; Huang, Baifei; Yang, Zhongyi; Yuan, Jiangang; Dai, Hongwen; Qiu, Qiu

    2010-03-15

    A pot experiment was conducted to investigate the stability of Cd and/or Pb accumulation in shoot of Cd and Pb pollution-safe cultivars (PSCs), the hereditary pattern of shoot Cd accumulation, and the transfer potentials of Cd and Pb in water spinach (Ipomoea aquatica Forsk.). A typical Cd-PSC, a typical non-Cd-PSC (Cd accumulative cultivar), a hybrid from the former two cultivars, and two typical Cd+Pb-PSCs were grown in seven soils with different concentrations of Cd and Pb. The results showed that concentrations of Cd and Pb in shoot of the PSCs were always lower than the non-PSC and the highest Cd and Pb transfer factors were also always observed in the non-PSC, indicating the stability of the PSCs in Cd and Pb accumulation. Shoot Cd concentration seemed to be controlled by high Cd dominant gene(s) and thus crossbreeding might not minimize Cd accumulation in water spinach. Interaction between Cd and Pb in soils affected the accumulations of the metals in shoot of water spinach. Under middle Cd and Pb treatments, the presence of higher Pb promoted the accumulation of Cd. However, under high Pb treatment, accumulations of Cd and Pb were both restricted. PMID:19875230

  18. Influence of the application renewal of glutamate and tartrate on Cd, Cu, Pb and Zn distribution between contaminated soil and Paulownia tomentosa in a pilot-scale assisted phytoremediation study.

    Science.gov (United States)

    Doumett, S; Fibbi, D; Azzarello, E; Mancuso, S; Mugnai, S; Petruzzelli, G; Del Bubba, M

    2011-01-01

    The influence of repeated applications of tartrate (TAR) and glutamate (GLU) at 50-mmol kg(-1) of soil on Cd, Cu, Pb, and Zn distribution between a contaminated soil and Paulownia tomentosa was investigated. TAR and GLU were applied by a single or a double dosage, the latter carried out with an interval between the two applications of thirty days. The comparison of the differences in mean amounts of metals accumulated in the whole plant at the end of single and double TAR and GLU application experiments indicated the positive effect of repeated GLU applications on the accumulation of Cu, Pb, and Zn by Paulownia tomentosa as compared to untreated controls. A similar effect was not observed for the TAR treatments. When soil treated with either TAR or GLU was compared with untreated controls, no significant effect on heavy-metal concentrations in the soil solution was observed 30 days after treatment, suggesting the absence of an increase of the long-term leaching risk of heavy metals in aquifers and surface waters due to the ligand application. A cost analysis of the treatment is also reported. PMID:21598764

  19. Bioaccumulation and Distribution of Heavy Metals (Cd, Cu, Fe, Ni, Pb and Zn in the Different Tissues of Chicoreus capucinus Lamarck (Mollusca: Muricidae Collected from Sungai Janggut, Kuala Langat, Malaysia

    Directory of Open Access Journals (Sweden)

    Franklin Edward Berandah

    2010-01-01

    Full Text Available Knowledge on accumulation and distribution of metals in the soft tissues may help us to understand the processes involved in the uptake and excretion of metals in the different parts of molluscs such as Chicoreus capucinus. Chicoreus capucinus was collected from intertidal areas of Sungai Janggut mudflat, Kuala Langat, Selangor and analysed for heavy metals content in the tissues. The capability of the different parts to accumulate heavy metal from the environment was measured by calculating their Biota-Sediment Accumulation Factor (BSAF values. From this preliminary investigation, it was found that the highest concentrations of Cu were found in the caecum (194±24.4 µg/g dw, Cd in digestive gland (32.9±0.000 µg/g dw and Fe in operculum (971±2.50 µg/g dw. For Ni and Pb, high concentrations in shell were observed and Zinc high levels in most of the tissues studied except shell and operculum. On the other hand, highest BSAF values were obtained in caecum for Cu (101.2, Zn (27.4 and Cd (53.1, while highest BSAF values were obtained in shell for Pb (32.6 and Ni (8.88. However, in general, most of the different parts of the gastropod could be suggested as macro concentrator organs, since the BSAF values were greater than 2. More studies should be conducted in the future to determine the potential of C. capucinus as biomonitor.

  20. Solid phase extraction of Cd(II), Pb(II), Zn(II) and Ni(II) from food samples using multiwalled carbon nanotubes impregnated with 4-(2-thiazolylazo)resorcinol

    International Nuclear Information System (INIS)

    Multiwalled carbon nanotubes were impregnated with 4-(2-thiazolylazo)resorcinol and used for the separation and preconcentration of Cd(II), Pb(II), Zn(II) and Ni(II) ions from food samples. The analytes were quantitatively recovered at pH 7. 0 and eluted with 3 mol L-1 acetic acid. The effects of pH value, flow rate, eluent type and sample volume on the recoveries, and the effects of alkali, earth alkali and transition metals on the retention of the analytes were studied. The method was validated using the standard certified reference materials SRM 1570A (spinach leaves) and IAEA 336 (lichen), and the results were found to be compatible with the certified values of reference materials. The new enrichment procedure was applied to the determination of these ions in various food samples. (author)

  1. The influence of metal speciation in combustion waste on the efficiency of Cu, Pb, Zn, Cd, Ni and Cr bioleaching in a mixed culture of sulfur-oxidizing and biosurfactant-producing bacteria.

    Science.gov (United States)

    Karwowska, Ewa; Wojtkowska, Małgorzata; Andrzejewska, Dorota

    2015-12-15

    Metal leachability from ash and combustion slag is related to the physico-chemical properties, including their speciation in the waste. Metals speciation is an important factor that influences the efficiency of metal bioleaching from combustion wastes in a mixed culture of acidophilic and biosurfactant-producing bacteria. It was observed that individual metals tended to occur in different fractions, which reflects their susceptibility to bioleaching. Cr and Ni were readily removed from wastes when present with a high fraction bound to carbonates. Cd and Pb where not effectively bioleached when present in high amounts in a fraction bound to organic matter. The best bioleaching results were obtained for power plant slag, which had a high metal content in the exchangeable, bound to carbonates and bound to Fe and Mg oxides fractions- the metal recovery percentage for Zn, Cu and Ni from this waste exceeded 90%. PMID:26073519

  2. Synthesis of high-surface-area {gamma}-Al{sub 2}O{sub 3} from aluminum scrap and its use for the adsorption of metals: Pb(II), Cd(II) and Zn(II)

    Energy Technology Data Exchange (ETDEWEB)

    Asencios, Yvan J.O., E-mail: yvan@iqsc.usp.br [Instituto de Quimica de Sao Carlos, Universidade de Sao Paulo, Av. Trabalhador Saocarlense, 400, 13560-970, Sao Carlos, SP (Brazil); Sun-Kou, Maria R., E-mail: msun@pucp.edu.pe [Seccion Quimica, Departamento de Ciencias, Pontificia Universidad Catolica del Peru, Av. Universitaria 1801, Lima 32 (Peru)

    2012-10-01

    Highlights: Black-Right-Pointing-Pointer Aluminum hydroxide obtained from aluminum scrap led to the formation of gamma alumina. Black-Right-Pointing-Pointer Acidic pH of precipitation favored the formation of small particles of high surface areas. Black-Right-Pointing-Pointer Higher aging temperature favored the formation of large structures of large pore sizes. Black-Right-Pointing-Pointer Higher aging temperature generated symmetrical solids of regular hexagonal prism forms. Black-Right-Pointing-Pointer Aluminas of large pores adsorbed metals as following: Pb (1.75 Angstrom-Sign ) > Cd (1.54 Angstrom-Sign ) > Zn (1.38 Angstrom-Sign ). - Abstract: Several types of alumina were synthesized from sodium aluminate (NaAlO{sub 2}) by precipitation with sulfuric acid (H{sub 2}SO{sub 4}) and subsequently calcination at 500 Degree-Sign C to obtain {gamma}-Al{sub 2}O{sub 3}. The precursor aluminate was derived from aluminum scrap. The various {gamma}-Al{sub 2}O{sub 3} synthesized were characterized by Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), adsorption-desorption of N{sub 2} (S{sub BET}) and scanning electron microscopy (SEM). XRD revealed that distinct phases of Al{sub 2}O{sub 3} were formed during thermal treatment. Moreover, it was observed that conditions of synthesis (pH, aging time and temperature) strongly affect the physicochemical properties of the alumina. A high-surface-area alumina (371 m{sup 2} g{sup -1}) was synthesized under mild conditions, from inexpensive raw materials. These aluminas were tested for the adsorption of Cd(II), Zn(II) and Pb(II) from aqueous solution at toxic metal concentrations, and isotherms were determined.

  3. Immobilization of Cd, Zn, and Pb from Soil Treated by Limestone with Variation of pH Using a Column Test

    Directory of Open Access Journals (Sweden)

    Sung-Wook Yun

    2015-01-01

    Full Text Available Decades of mining in South Korea have resulted in the contamination of large amounts of soil by metals. The most feasible approach to site restoration requires the use of a stabilization agent to reduce metal mobility. This study examined the leaching characteristics of limestone used as a stabilization agent when subjected to solutions of differing pH. In a laboratory-scale column test, solutions with pH values of 3.5, 4.6, and 5.6, representing acidic to nonacidic rainfall, were applied to soil mixed with limestone. Test results indicate that metal components can be released with the addition of acidic solutions, even if the soil is highly alkaline. Cd and Zn, in particular, exhibited abrupt or continuous leaching when exposed to acid solutions, indicating the potential for contamination of water systems as metal-laden soils are exposed to the slightly acidic rainfall typical of South Korea. Treatment using stabilization agents such as limestone may reduce leaching of metals from the contaminated soil. Stabilizing metal-contaminated farmland is an economical and feasible way to reduce pollutants around abandoned metal mines.

  4. Zn/Cd ratios and cadmium isotope evidence for the classification of lead-zinc deposits

    Science.gov (United States)

    Wen, Hanjie; Zhu, Chuanwei; Zhang, Yuxu; Cloquet, Christophe; Fan, Haifeng; Fu, Shaohong

    2016-04-01

    Lead-zinc deposits are often difficult to classify because clear criteria are lacking. In recent years, new tools, such as Cd and Zn isotopes, have been used to better understand the ore-formation processes and to classify Pb-Zn deposits. Herein, we investigate Cd concentrations, Cd isotope systematics and Zn/Cd ratios in sphalerite from nine Pb-Zn deposits divided into high-temperature systems (e.g., porphyry), low-temperature systems (e.g., Mississippi Valley type [MVT]) and exhalative systems (e.g., sedimentary exhalative [SEDEX]). Our results showed little evidence of fractionation in the high-temperature systems. In the low-temperature systems, Cd concentrations were the highest, but were also highly variable, a result consistent with the higher fractionation of Cd at low temperatures. The δ114/110Cd values in low-temperature systems were enriched in heavier isotopes (mean of 0.32 ± 0.31‰). Exhalative systems had the lowest Cd concentrations, with a mean δ114/110Cd value of 0.12 ± 0.50‰. We thus conclude that different ore-formation systems result in different characteristic Cd concentrations and fraction levels and that low-temperature processes lead to the most significant fractionation of Cd. Therefore, Cd distribution and isotopic studies can support better understanding of the geochemistry of ore-formation processes and the classification of Pb-Zn deposits.

  5. Assessment Of Heavy Metal Contamination Of Water Sources From Enyigba Pb-Zn District South Eastern Nigeria

    Directory of Open Access Journals (Sweden)

    Nnabo Paulinus N

    2015-08-01

    Full Text Available Abstract A total of thirty 30 water samples were collected from the Enyigba PbZn mining district to assess the contamination of the water sources as a result of mining of lead and zinc minerals in the area. This comprises of 12 samples of surface water 14 from mine ponds and 4 from underground borehole water. The samples were acidified to stabilize the metals for periods more than four days without the use of refrigeration. The acidified water samples were analysed by a commercial laboratory at Projects Development Institute PRODA Enugu using Atomic Absorption Spectroscopy AAS. The elements determined by this method are lead Pb zinc Zn copper Cu arsenic As cadmium Cd nickel Ni manganese Mn and cobalt Co. The result and analysis of contamination factor showed that in surface water Cd had the highest concentration followed by As and Pb while Ni had the lowest. In mine ponds Cd also had the highest concentration and followed by Pb and As and Ni the lowest. In borehole water Cd has the highest concentration followed by Pb and As while Ni had the lowest concentration. Compared to WHO permissible limits the contamination of the heavy metals in all water sources are in order CdAsPbNiZnCu. In surface water the order is CdAsPbNiZnCu in mine ponds it is CdPbAsNiZnCu and in borehole water the order is CdAsPbZnNiCu. The calculated contamination factors show very high contamination status for Cd Pb and As. These levels of contamination and values indicate that under the prevailing conditions and environmental regulations in Nigeria the mining district would face major and hazardous discharges of these metals to the water sources.

  6. Evolution with time of 12 metals (V, Cr, Mn, Co, Cu, Zn, Ag, Cd, Ba, Pb, Bi and U) and of lead isotopes in the snows of Coats Land (Antarctica) since the 1830's

    International Nuclear Information System (INIS)

    This work shows that it is now possible to get reliable data on the occurrence of numerous heavy metals at ultra low levels in Antarctic snow, by combining ultra clean field sampling and laboratory sub-sampling procedures and the use of ultra sensitive analytical techniques such as ICP-SFMS and TIMS. It has allowed us to determine concentrations of twelve metals (V, Cr, Mn, Co, Cu, Zn, Ag, Cd, Ba, Pb, Bi et U) and lead isotopic composition in the ultra clean series of snow samples collected at Coats Land, in the Atlantic sector of Antarctica. This work presents a 150 years record of metal inputs from natural and anthropogenic sources to Antarctica from the 1830's to the early 1990's. Lead atmospheric pollution begins as early as the end of the 19. century, peaks during the 1970's-1980's and then falls sharply during recent decades. Evolution in lead isotopic abundance shows that Pb inputs to Antarctica reflect a complex blend of contributions originating from the Southern part of South America and Australia. For Cr, Cu, Zn, Ag, Bi and U, concentrations in the snow show significant increases from 1950 to 1980. These enhancements which cannot be explained by variations in natural inputs, illustrate that atmospheric pollution for heavy metals linked with anthropogenic activities in the Southern Hemisphere countries such as for example ferrous and non-ferrous metal mining and smelting is really global. Study of the time period 1920-1990, has allowed us to detail short-term (intra and inter annual) heavy metals concentration's changes. The large short-term variability, observed in Coats Land snow, shows the complex patterns of metal inputs to Antarctica, associated for instance to changes in long-range transport processes from mid-latitude to polar zone and to variability in the different natural sources, such local volcanic activity, sea-salt spray or crustal dust inputs. (author)

  7. Tellurium antisites in CdZnTe

    Science.gov (United States)

    Chu, Muren; Terterian, Sevag; Ting, David; James, Ralph B.; Erickson, Jay C.; Yao, H. Walter; Lam, Terrance T.; Szawlowski, Marek; Szczebiot, Richard W.

    2001-12-01

    The n-type conduction of CdTe and Cd0.96Zn0.04Te crystals grown from melts with excess tellurium indicates that the origin of the donors with an energy level at 0.01 eV below the conduction band are most likely singly ionized tellurium antisites instead of cadmium interstitials. Based on this model, the deep level at 0.75 eV below the conduction band is therefore doubly ionized tellurium antisites. After increasing the zinc content over 7%, CdZnTe turns to p-type. The conduction type variation of CdZnTe crystals as a function of zinc contents is explained by the compensation between the donors of Te-antisites and the acceptors of Cd vacancies. High resitivity Cd0.9Zn0.1Te crystals are produced by compensating the p-type crystals with indium at a low doping level of 1- 5x1015 cm-3. At room temperature, the high yield CdZnTe radiation detectors can resolve the six low energy peaks from the Am241 source, a performance comparable to the best reported CdZnTe detectors.

  8. Localisation and quantification of elements within seeds of Cd/Zn hyperaccumulator Thlaspi praecox by micro-PIXE.

    Science.gov (United States)

    Vogel-Mikus, Katarina; Pongrac, Paula; Kump, Peter; Necemer, Marijan; Simcic, Jure; Pelicon, Primoz; Budnar, Milos; Povh, Bogdan; Regvar, Marjana

    2007-05-01

    Cd, Zn and Pb accumulation, spatial distribution within seeds and germinating seedlings, and seeds fitness of metal hyperaccumulating Thlaspi praecox were investigated in order to gain more knowledge on plant reproductive success at metal polluted sites. The seeds contained up to 1351 microg g-1 (dry weight) of Cd, 121 microg g-1 of Zn and 17 microg g-1 of Pb. Seed fitness was negatively influenced by seed Cd hyperaccumulation. Nevertheless, the viability of seeds was decreased by maximally 20%, indicating very efficient tolerance of the plant embryos to Cd. Localisation by micro-PIXE revealed preferential storage of most elements in the embryonic axis. Cd and Zn were preferentially localised in the epidermis of cotyledons. The restriction of seed Pb and Zn uptake and hyperaccumulation of Cd, accompanied by partitioning of Cd in the epidermal tissues of cotyledons, may enable the survival of T. praecox embryos and seedlings in Cd polluted environments. PMID:17070633

  9. M(II) transfer across a liquid-liquid microinterface facilitated by a complex formation with 8-Hydroxyquinoline: Application to quantification of Pb(II), Cd(II) and Zn(II) alone or in mixture in effluents

    International Nuclear Information System (INIS)

    Highlights: • Study of assisted transfer of lead ions by 8-HQ at water/1,2-DCE for the first time. • Formation of a monocharged specie in good agreement with the solution chemistry. • Possible quantification by cyclic and square wave voltammetry measurements. • Quantification of Pb(II) ions until 0.2 ppm lower than the limit fixed in industrial effluents. • Highlighting of the interesting overall quantification of heavy metals: Lead, Cadmium and Zinc. - Abstract: For the first time, the assisted transfer of Pb(II) across a water/1,2-Dichloroethane (DCE) microinterface was investigated in the presence of 8-Hydroxyquinoline (named also oxine or 8-HQ) in the organic phase. A monocharged complex was formed in the aqueous phase and then transferred in the organic phase. A good relationship was obtained between currents and Pb(II) concentrations in the 10−4 to 5 10−3 M range and 10−5 to 6 10−5 M range using cyclic voltammetry and square wave voltammetry respectively. In presence of other heavy metals such as Cd(II) and Zn(II), only one electrochemical process is observed regardless of the mixture. Moreover, stationary currents increase in direct linear relation with the sum of M(II) concentrations added in water, allowing an overall detection of heavy metals. This result indicates that this method can be very interesting for monitoring all toxic metals in effluents. The limit of detection was found equal to 0.2 ppm for lead. This value allows us to reach levels significant for industrial effluents, in comparison to the limits fixed by the French ministry of ecology for lead, cadmium and zinc to 0.5 ppm, 0.2 ppm and 2.0 ppm respectively. This study highlights the real interest of devices based on a liquid-liquid microinterface

  10. High-Efficiency Photochemical Water Splitting of CdZnS/CdZnSe Nanostructures

    Directory of Open Access Journals (Sweden)

    Chen-I Wang

    2013-01-01

    Full Text Available We have prepared and employed TiO2/CdZnS/CdZnSe electrodes for photochemical water splitting. The TiO2/CdZnS/CdZnSe electrodes consisting of sheet-like CdZnS/CdZnSe nanostructures (8–10 μm in length and 5–8 nm in width were prepared through chemical bath deposition on TiO2 substrates. The TiO2/CdZnS/CdZnSe electrodes have light absorption over the wavelength 400–700 nm and a band gap of 1.87 eV. Upon one sun illumination of 100 mW cm−2, the TiO2/CdZnS/CdZnSe electrodes provide a significant photocurrent density of 9.7 mA cm−2 at −0.9 V versus a saturated calomel electrode (SCE. Incident photon-to-current conversion efficiency (IPCE spectrum of the electrodes displays a maximum IPCE value of 80% at 500 nm. Moreover, the TiO2/CdZnS/CdZnSe electrodes prepared from three different batches provide a remarkable photon-to-hydrogen efficiency of 7.3 ± 0.1% (the rate of the photocatalytically produced H2 by water splitting is about 172.8 mmol·h−1·g−1, which is the most efficient quantum-dots-based photocatalysts used in solar water splitting.

  11. 石墨烯-硒化物量子点复合物的制备与性能研究%Properties and synthesis of graphene-metal (Pb, Zn, Cd) selenium composites

    Institute of Scientific and Technical Information of China (English)

    傅小奇; 王双; 赵谦; 姜廷顺

    2012-01-01

    Graphene-metal selenium quantum dots (QDs) composites have been prepared by π-π stacking of pyri- dine-capped metal selenium QDs and chemically converted graphene (CCG) in aqueous solution. The aromatic structures of pyridine capped on metal selenium QDs introduce a π-π stacking interaction between CCG and QDs, and extend the coniugated structure of CCG. The structural details and formation mechanism of the re- sultant graphene-metal selenium QDs composites were characterized by X-ray diffraction, UV-Vis absorption, transmission electron microscope and Raman scattering studies. The CCG-metal selenium composites disperse stably in aqueous solution, allows them to be potentially used in biological tissues and further application. The cyclic voltammetry experimental result shows that the electrochemical performances of CCG-ZnSe were greatly improved than that of pure CCG, ZnSe powder.%利用表面包覆1层吡啶分子的量子点和化学还原性石墨烯通过π-π堆积的方式,制备了石墨烯-量子点(PbSe、ZnSe、CdSe)复合物。包覆在量子点外层的吡啶分子芳香环结构起到桥梁的作用,将石墨烯和量子点π-π堆积起来,同时延伸了石墨烯的共轭结构。通过XRD、UV-Vis、TEM、Raman等表征手段,考察了相应复合物的结构、形成机理与性质。所制石墨烯-量子点复合物能稳定分散于水或极性溶液中,使得此类石墨烯复合物在生物体内具有良好的应用前景。通过循环伏安法对制备的产物进行了电化学性能测试。根据循环伏安曲线,复合物CCG-ZnSe的电容较单纯的CCG、ZnSe有大幅提高。

  12. Synthesis of near-infrared-emitting CdTe/CdSe/ZnSe/ZnS heterostructure.

    Science.gov (United States)

    Yang, Ping

    2014-04-01

    Near-infrared-emitting quantum dots (QDs) were fabricated via organic synthesis strategies through constructing CdTe/CdSe/ZnSe/ZnS multishell heterostructure. An effective shell-coating route was developed for multishell growth on CdTe cores. Core/shell growth was monitored by absorption and photoluminescence (PL) spectroscopy and transmission electron microscopy observation. Yellow emitting CdTe cores were coated with a CdSe shell to generate type II structure. This yields core/shell QDs with red photoluminescence. The passivation by the ZnSe shell having a substantially wide bandgap confines the excitons within the CdTe/CdSe interface and isolates them from the solution environment and consequently improves the stability of the heterostructure. An additional ZnS shell was deposited around the outer layer of CdTe/CdSe/ZnSe QDs to form a heterostructure through the reaction between zinc oleate and trioctylphosphine sulfur in the crude CdTe/CdSe/ZnSe solution. By varying CdTe core size and each shell thickness, the PL wavelength of the obtained heterostructure can span from 580 to 770 nm. The PL efficiency is quenched in CdTe QDs in diluted solution but increases substantially up to 24% for CdTe/CdSe core/shell QDs. The PL efficiency of CdTe/CdSe/ZnSe/ZnS QDs with average diameter of 5.4 nm and a PL peak wavelength of 770 nm is 20%. PMID:24734747

  13. The accumulation of elements in plants growing spontaneously on small heaps left by the historical Zn-Pb ore mining.

    Science.gov (United States)

    Stefanowicz, Anna M; Stanek, Małgorzata; Woch, Marcin W; Kapusta, Paweł

    2016-04-01

    The study evaluated the levels of nine metals, namely Ca, Cd, Fe, K, Mg, Mn, Pb, Tl, and Zn, in soils and tissues of ten plant species growing spontaneously on heaps left by historical mining for Zn-Pb ores. The concentrations of Cd, Pb, Tl, and Zn in heap soils were much higher than in control soils. Plants growing on heaps accumulated excessive amounts of these elements in tissues, on average 1.3-52 mg Cd kg(-1), 9.4-254 mg Pb kg(-1), 0.06-23 mg Tl kg(-1) and 134-1479 mg Zn kg(-1) in comparison to 0.5-1.1 mg Cd kg(-1), 2.1-11 mg Pb kg(-1), 0.02-0.06 mg Tl kg(-1), and 23-124 mg Zn kg(-1) in control plants. The highest concentrations of Cd, Pb, and Zn were found in the roots of Euphorbia cyparissias, Fragaria vesca, and Potentilla arenaria, and Tl in Plantago lanceolata. Many species growing on heaps were enriched in K and Mg, and depleted in Ca, Fe, and Mn. The concentrations of all elements in plant tissues were dependent on species, organ (root vs. shoot), and species-organ interactions. Average concentrations of Ca, K, and Mg were generally higher in shoots than in roots or similar in the two organs, whereas Cd, Fe, Pb, Tl, and Zn were accumulated predominantly in the roots. Our results imply that heaps left by historical mining for Zn-Pb ores may pose a potential threat to the environment and human health. PMID:26635220

  14. Determination of Mg, Al, Fe, Zn, Cd, Pb and Analysis of Constituents of Essential Oil in Alpinia Oxyphylla Miq%益智仁中Mg、Al、Fe、Zn、Cd、Pb含量及精油成分分析

    Institute of Scientific and Technical Information of China (English)

    陈少东; 陈福北; 刘红星; 卢平; 聂坤梅

    2011-01-01

    文章以ICP-MS法测定益智仁中Mg、Al、Fe、Zn、Cd、Pb六种元素含量,并用水蒸汽法提取精油,通过气相一质谱(GC-MS)联用手段对精油的主要化学成分进行分析,以峰面积归一化法确定各组分的相对含量;结果从益智仁精油中分离出28个色谱峰,并鉴定了其中的25种成分,占精油总含量的94.08%,其主要成分依次为圆柚酮(15.51%)、γ-榄香烯(10.71%)、朱栾倍半萜(瓦伦烯)(8.69%)、α-芹子烯(6.71%)等,从元素测定来看Mg含量很高达6550μg/g,Pb含量很低,仅1.59μg/g。%The contents of 6 inorganic elements in Alpinia Oxyphylla Miq. Such as Mg, Al, Fe, Zn, Cd, Pb were determined by ICP-MS, and the essential oil was extracted by steam distillation and analysised by gas chromatography-mass spectrometry (GC-MS), 28 peaks were separated, of which 25 compounds were identified , accounted for 94.08% of the oil,with Nootkatone (15.51%),y-Selinene(10.71%),Valencene(8.69%), a-Selinene(6.71%)etc as the main ingredient. The results showed that the Alpinia Oxyphylla Miq. Is rich in elements Mg (6550 ug/g) and trace in Pb is poor (only 1.59 (xg/g).

  15. 一种新的多金属超富集植物--圆锥南芥(Arabis paniculata L.)%A New Found Pb/Zn/Cd Hyperaccumulator-Arabis Paniculata L.

    Institute of Scientific and Technical Information of China (English)

    汤叶涛; 仇荣亮; 曾晓雯; 方晓航

    2005-01-01

    野外调查和营养液培养试验表明,圆锥南芥(Arabis Paniculata L.)具有超量富集Pb/Zn/Cd的能力,是国内首次发现的Pb/Zn/Cd多金属超富集植物,它的出现填补了国内多金属超富集植物的空白,为重金属复合污染土壤的植物修复提供了新的种质资源.

  16. Voltammetric determination of Pb, Cd, Zn, Cu and Se in milk and dairy products collected from Iran: An emphasis on permissible limits and risk assessment of exposure to heavy metals.

    Science.gov (United States)

    Shahbazi, Yasser; Ahmadi, Farhad; Fakhari, Farnoosh

    2016-02-01

    This study was carried out to determine the concentrations of some heavy metals in dairy products, collected from five industrial regions in Iran (n = 250 samples) during winter and summer in 2013. The samples were analyzed using the differential pulse anodic and cathodic stripping voltammetry technique. The obtained ranges of mean Pb, Cd, Cu, Zn and Se were as follow: in raw milk 14.0, 1.11, 427, 571, 2.19 μg kg(-1), in pasteurized milk 9.59, 1.0, 378, 447, 1.78 μg kg(-1), in cheese 14.5, 1.25, 428, 586, 1.68 μg kg(-1), in yoghurt 7.54, 0.99, 399, 431, 1.23 μg kg(-1) and in doogh 7.2, 0.84, 320, 369, 0.99 μg kg(-1), respectively. In nearly all cases the concentrations of the metals were below the international permissible limits and do not pose a health concern for the consumption of milk and dairy products in Iran. PMID:26304448

  17. Effect of temperature, gas phase composition, pH and microbial activity on As, Zn, Pb and Cd mobility in selected soils in the Ebro and Meuse Basins in the context of global change

    International Nuclear Information System (INIS)

    This study estimates the effect of environmental parameters on the mobility of four inorganic contaminants (As, Zn, Pb and Cd) in soils from three areas in the Ebro and Meuse River basins, within the context of global change. An experimental method, applicable to various soil systems, is used to measure the effect of four global-change-sensitive parameters (temperature, gas phase composition, pH and microbial activity). The aqueous phase of batch incubations was sampled regularly to monitor toxic element concentrations in water. Statistical processing enabled discrimination of the most relevant variations in dissolved concentrations measured at different incubation times and under different experimental conditions. Gas phase composition was identified as the most sensitive parameter for toxic element solubilization. This study confirms that total soil concentrations of inorganic pollutants are irrelevant when assessing the hazard for ecosystems or water resource quality. - An experimental method applicable for different soil systems enables the determination of the effect of environmental parameters, potentially affected by global change, on the mobilization of inorganic pollutants

  18. Chitosan film loaded with silver nanoparticles-sorbent for solid phase extraction of Al(III), Cd(II), Cu(II), Co(II), Fe(III), Ni(II), Pb(II) and Zn(II).

    Science.gov (United States)

    Djerahov, Lubomir; Vasileva, Penka; Karadjova, Irina; Kurakalva, Rama Mohan; Aradhi, Keshav Krishna

    2016-08-20

    The present study describes the ecofriendly method for the preparation of chitosan film loaded with silver nanoparticles (CS-AgNPs) and application of this film as efficient sorbent for separation and enrichment of Al(III), Cd(II), Cu(II), Co(II), Fe(III), Ni(II), Pb(II) and Zn(II). The stable CS-AgNPs colloid was prepared by dispersing the AgNPs sol in chitosan solution at appropriate ratio and further used to obtain a cast film with very good stability under storage and good mechanical strength for easy handling in aqueous medium. The incorporation of AgNPs in the structure of CS film and interaction between the polymer matrix and nanoparticles were confirmed by UV-vis and FTIR spectroscopy. The homogeneously embedded AgNPs (average diameter 29nm, TEM analysis) were clearly observed throughout the film by SEM. The CS-AgNPs nanocomposite film shows high sorption activity toward trace metals under optimized chemical conditions. The results suggest that the CS-AgNPs nanocomposite film can be feasibly used as a novel sorbent material for solid-phase extraction of metal pollutants from surface waters. PMID:27178907

  19. Spectroscopic properties of some new azo-azomethine ligands in the presence of Cu2+, Pb2+, Hg2+, Co2+, Ni2+, Cd2+ and Zn2+ and their antioxidant activity

    Science.gov (United States)

    Shaghaghi, Zohreh

    2014-10-01

    Due to their potential applicability as selective receptors in optical sensors, two novel azo Schiff-base derivatives I and II are synthesized and characterized with FT-IR, 1H NMR and elemental analysis techniques. The optical response of azo groups of I and II towards Ni2+, Co2+, Cu2+, Pb2+, Hg2+, Zn2+ and Cd2+ metal ions is studied in DMSO by UV-vis spectroscopy. The absorption spectra of both compounds with cations show marked changes. In solution, azo Schiff-base I produces a cation induced 95 nm blue shift for Cu2+ ion from 555 nm to 460 nm with remarkable color change from red to yellow. Whereas no significant color change is observed upon addition of studied metal cations to the solution of ligand II or other metal ions to the solution of ligand I. Furthermore, Job's plot indicate 1:1 binding-stoichiometry for I with Cu2+ ion and Benesi-Hildebrand plot is used for the determination of its association constant. Therefore receptor I is highly specific for copper ions in DMSO solution. Finally, the study of antioxidant properties of I and II with DPPH method reveals high and significant activities.

  20. Evaluation de la contamination de la chaîne trophique par les éléments traces (Cu, Co, Zn, Pb, Cd, U, V et As dans le bassin de la Lufira supérieure (Katanga/RD Congo

    Directory of Open Access Journals (Sweden)

    Katemo Manda, B.

    2010-01-01

    Full Text Available Evaluation of Contamination of the Food Chain by Trace Elements (Cu, Co, Zn, Pb, Cd, U, V and As in the Basin of the Upper Lufira (Katanga/DR Congo. Seven trace elements (Cu, Co, Zn, Cd, Pb, U, V and As were analyzed using a HR ICP-MS in samples of water, plankton, leaves of Phragmites australis, muscle and gills of three fish species (Oreochromis macrochir, Tilapia rendalli, Clarias gariepinus collected in the basin of the upper Lufira. The results indicate a high copper (70.9 ppm and cobalt (32.3 ppm content in the effluent of complex hydrometallurgical Shituru. If contamination of rivers decreases with distance from the pollution source, the values are very high in lake Tshangalele for plankton and leaves of P. australis. For fish, the results indicate that Pb, U, V, Cu, Co and Cd accumulates preferentially in the gills but Zn accumulates more in the muscles. As accumulates in the same order of magnitude in both organs. These results confirm the pollution of the basin by the effluents from Lufira complex hydrometallurgical Shituru.

  1. Abandoned PbZn mining wastes and their mobility as proxy to toxicity: A review.

    Science.gov (United States)

    Gutiérrez, Mélida; Mickus, Kevin; Camacho, Lucy Mar

    2016-09-15

    Lead and zinc (PbZn) mines are a common occurrence worldwide; and while approximately 240 mines are active, the vast majority have been abandoned for decades. Abandoned mining wastes represent a serious environmental hazard, as Pb, Zn and associated metals are continuously released into the environment, threatening the health of humans and affecting ecosystems. Iron sulfide minerals, when present, can form acid mine drainage and increase the toxicity by mobilizing the metals into more bioavailable forms. Remediation of the metal waste is costly and, in the case of abandoned wastes, the responsible party(ies) for the cleanup can be difficult to determine, which makes remediation a complex and lengthy process. In this review, we provide a common ground from a wide variety of investigations about concentrations, chemical associations, and potential mobility of Pb, Zn and cadmium (Cd) near abandoned PbZn mines. Comparing mobility results is a challenging task, as instead of one standard methodology, there are 4-5 different methods reported. Results show that, as a general consensus, the metal content of soils and sediments vary roughly around 1000mg/kg for Zn, 100 for Pb and 10 for Cd, and mobilities of Cd>Zn>Pb. Also, mobility is a function of pH, particle size, and formation of secondary minerals. New and novel remediation techniques continue to be developed in laboratories but have seldom been applied to the field. Remediation at most of the sites has consisted of neutralization (e.g. lime,) for acid mine discharge, and leveling followed by phytostabilization. In the latter, amendments (e.g. biochar, fertilizers) are added to boost the efficiency of the treatment. Any remediation method has to be tested before being implemented as the best treatment is site-specific. Potential treatments are described and compared. PMID:27179321

  2. Structural and luminescence studies on Eu3+: B2O3–Li2O–MO–LiF (M=Ba, Bi2, Cd, Pb, Sr2 and Zn) glasses

    International Nuclear Information System (INIS)

    The present work reports the structural and luminescence studies on 54B2O3+25Li2O+15MO+ 5LiF+1Eu2O3 (where M=Ba, Bi2, Cd, Pb, Sr2 and Zn) glasses prepared by following melt quenching technique. The influence of the metal ions in the host matrix have been studied by measuring FTIR, absorption, excitation and emission spectra. FTIR studies explore the presence of the functional units in the prepared glasses. Through the optical absorption spectra bonding parameters (β¯, δ), direct and indirect allowed band gap and Urbach energy (ΔE) values were calculated and reported. Due to some defects associated with the addition of various oxides in to the host matrix, the Urbach energy values changes inversely with the optical band gap. The phonon side band have also been observed on the high energy side of the 7F0→5D2 transition in the excitation spectra due to the coupling between the coordination ions and Eu3+ ions. Judd–Ofelt (JO) intensity parameters have been determined from the luminescence spectra and is used to explore the nature of the Eu3+ ions with its surrounding ligands. The JO parameters have been used to calculate the stimulated emission cross-section (σPE), branching ratios (βR) and radiative lifetime (τR) for the 5D0→7FJ (J=1, 2, 3 and 4) transitions of the Eu3+ ions in the prepared glasses. The experimental lifetime of the 5D0 level in the Eu3+ doped lithium fluoroborate glasses have been calculated and reported. The longer lifetime of the 5D0 metastable state indicates that the prepared glasses are suitable for laser applications. -- Highlights: ► The bonding parameter studies reveal the covalent nature of prepared glasses. ► Higher R and Ω2 confirms the hypersensitive nature/higher asymmetry of the glasses. ► Higher σPE values of the Eu:ZnLFB glass lead to give high optical gain. ► Difference in τexp and τR is due to the presence of OH group and nonradiative decay. ► Eu:ZnLFB glass possess higher σPE, βR and η potential for red

  3. Concentrations, spatial distribution, and risk assessment of soil heavy metals in a Zn-Pb mine district in southern China.

    Science.gov (United States)

    Qi, Jianying; Zhang, Hailong; Li, Xiangping; Lu, Jian; Zhang, Gaosheng

    2016-07-01

    China is one of the largest producers and consumers of lead and zinc in the world. Lead and zinc mining and smelting can release hazardous heavy metals such as Cd, Pb, Zn, and As into soils, exerting health risks to human by chronic exposure. The concentrations of Cd, Zn, Pb, and As in soil samples collected from a Pb-Zn mining area with exploitation history of 60 years were investigated. Health risks of the heavy metals in soil were evaluated using US Environmental Protection Agency (US EPA) recommended method. A geo-statistical technique (Kriging) was used for the interpolation of heavy metals pollution and Hazard Index (HI). The results indicated that the long-term Pb/Zn mining activities caused the serious pollution in the local soil. The concentrations of Cd, As, Pb, and Zn in topsoil were 40.3 ± 6.3, 103.7 ± 37.3, 3518.4 ± 896.1, and 10,413 ± 2973.2 mg/kg dry weight, respectively. The spatial distribution of the four metals possessed similar patterns, with higher concentrations around Aayiken (AYK), Maseka (MSK), and Kuangshan (KS) area and more rapidly dropped concentrations at upwind direction than those at downwind direction. The main pollutions of Cd and Zn were found in the upper 60 cm, the Pb was found in the upper 40 cm, and the As was in the upper 20 cm. The mobility of metals in soil profile of study area was classed as Cd > Zn ≫ Pb > As. Results indicated that there was a higher health risk (child higher than adult) in the study area. Pb contributed to the highest Hazard Quotient (57.0 ~ 73.9 %) for the Hazard Index. PMID:27315126

  4. Advance in Study of Pb, Zn, Cu and Cd Hyperaccumulators%Pb、Zn、Cu、Cd的超富集植物研究进展

    Institute of Scientific and Technical Information of China (English)

    何兰兰; 角媛梅; 王李鸿; 周鸿斌

    2009-01-01

    我国矿产资源丰富,矿区重金属污染十分严重,Pb、Zn、u、Cd四种重金属的污染在我国极其严重.利用超富集植物修复矿区重金属污染土壤,较传统方法而占是一种可靠经济安全的技术.综述了Pb.Zn、Cu、Cd四种重金属超富集植物,分析了可用于的我国重金属超富集植物的分布情况和生活环境,为土壤重金属污染的生态恢复提供参考.

  5. Geogenic and Anthropogenic Moss Responsiveness to Element Distribution Around a Pb-Zn Mine, Toranica, Republic of Macedonia.

    Science.gov (United States)

    Angelovska, Svetlana; Stafilov, Trajče; Šajn, Robert; Balabanova, Biljana

    2016-04-01

    Moss species (Homalothecium lutescens, Hypnum cupressiforme, Brachythecium glareosum, and Campthotecium lutescens) were used as suitable sampling media for biomonitoring the origin of heavy-metal pollution in the lead-zinc (Pb-Zn) mine "Toranica" near the Kriva Palanka town, Eastern Macedonia. The contents of 20 elements-silver (Ag), aluminum (Al), arsenic (As), barium (Ba), calcium (Ca), cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), potassium (K), lithium (Li), magnesium (Mg), manganese (Mn), sodium (Na), nickel (Ni), Pb, strontium (Sr), vanadium (V), and (Zn) were determined by atomic emission spectrometry with inductively coupled plasma. Data processing was applied with combinations of multivariate statistical methods: factor analysis, principal component analysis, and cluster analysis. Moss' responsiveness to the atmospheric distribution of the selected elements was investigated in correlation to the specific geology of the region (soil dusting). Lithogenic distribution was characterized with the distribution of three dominant geochemical associations: F1: Al-Li-V-Cr-Ni-Co, F2: Ba-Ca-Sr, and F3: Cd-Zn-Pb-Cu. Spatial distribution was constructed for visualization of the factor deposition. Furthermore, air distribution (passive biomonitoring) versus soil geochemistry of the analyzed elements was examined. Significant correlations were singled out for Pb, Zn, and Cd and for Mg(moss)/Na(soil). Characteristic lithological anomaly characterized the presence of the oldest geological volcanic rocks. Zone 1 (Pb-Zn mine surrounding) presents a unique area with hydrothermal action of Pb-Zn mineralization leading to polymetallic enrichments in soil. This phenomenon strongly affects the environment, which is a natural geochemical imprint in this unique area (described with the strong dominance of the geochemical association Cd-Zn-Pb-Cu). PMID:26888226

  6. High temperature continuous flow synthesis of CdSe/CdS/ZnS, CdS/ZnS, and CdSeS/ZnS nanocrystals

    Science.gov (United States)

    Naughton, Matt S.; Kumar, Vivek; Bonita, Yolanda; Deshpande, Kishori; Kenis, Paul J. A.

    2015-09-01

    Continuous flow reactors show great promise for large-scale synthesis of quantum dots. Here, we discuss results for the synthesis of multi-layered Cd-based hybrid nanocrystals - CdSe/CdS/ZnS, CdS/ZnS, and CdSeS/ZnS - in a continuous flow reactor. The simple reactor design and liquid-phase chemistry obviate the need for preheating or in-line mixing, and the chosen reactor dimensions and operating conditions allow for high flow rates (~10 mL min-1). Additionally, the simple reactor design is well suited for scale-up. The CdSe/CdS/ZnS particles synthesized at elevated temperatures in the reactor exhibit quantum yields of over 60% at longer wavelengths (red region). The shell growth for these particles is conducted without the need for complex dropwise addition or SILAR shell growth procedures used in batch reactors. CdS-based particles were shown to have a higher performance when using octadecene-S instead of TOP-S, which improved the quality of shell growth. In addition, stoichiometric synthesis of the alternate CdSeS/ZnS alloy particles was conducted, removing the need for a large excess of S to offset the lower S reactivity. CdSeS/ZnS alloy nanoparticles exhibit quantum yields of about 50% in the intermediate wavelength range (500-600 nm).Continuous flow reactors show great promise for large-scale synthesis of quantum dots. Here, we discuss results for the synthesis of multi-layered Cd-based hybrid nanocrystals - CdSe/CdS/ZnS, CdS/ZnS, and CdSeS/ZnS - in a continuous flow reactor. The simple reactor design and liquid-phase chemistry obviate the need for preheating or in-line mixing, and the chosen reactor dimensions and operating conditions allow for high flow rates (~10 mL min-1). Additionally, the simple reactor design is well suited for scale-up. The CdSe/CdS/ZnS particles synthesized at elevated temperatures in the reactor exhibit quantum yields of over 60% at longer wavelengths (red region). The shell growth for these particles is conducted without the need

  7. ZnSe-ZnMnSe and CdTe-CdMnTe superlattices

    Science.gov (United States)

    Gunshor, R. L.; Kolodziejski, L. A.; Otsuka, N.; Datta, S.

    1986-08-01

    We report the growth and characterization of superiattices of a new wide-gap, zincblende material system, Zn 1 - xMn xSe. ZnSe exhibiting dominant free excitonic emission in photoluminescence (PL) is the well material, while wider-band-gap Zn 1 - xMn xSe (0.23 efficiency compared to films of the ZnSe well material, while transmission electron microscopy shows extremely abrupt interfaces by the presence of seventh-order satellite spots. Previously reported superiattices in the CdTe-CdMnTe material system were grown with the (111) orientation, and exhibit unique excitonic properties believed related to the (111) interfaces. Using various techniques to select (111) or (100) heteroepitaxy of CdTe on (100) GaAs, we report the first (100) superlattices of this material, and compare the optical properties to the previous (111) structures.

  8. 微波消解-原子吸收法快速测定羽毛中的铜锌铬铅镉%Rapid determination of Cu,Zn, Cr,Pb and Cd in feather by microwave digestion-atomic absorption spectrometry method

    Institute of Scientific and Technical Information of China (English)

    黎鲜茗; 周西林

    2013-01-01

    提出了微波消解原子吸收法测定改性羽毛中铜、锌、铬、铅、镉的分析方法.采用在密闭容器中,用HNO3和HClO4混酸做溶剂在微波状态下消解改性羽毛样品,样品溶解完毕泄压后,定容,用快速序列分析功能的原子吸收仪同时测定铜、锌、铬、铅、镉的含量,快速高效.同时考察了微波消解称样量、溶剂用量及共存离子对分析结果的影响,其标准样品的测定结果与标准值一致.本法适应于改性羽毛中铜、锌、铬、铅、镉的测定.%The contents of Cu, Zn, Cr, Pb and Cd in modified feather were determined by microwave digestion-atomic absorption spectrometry method. The feather was dissolved by mixture of HN03 and HClO4 under microwave. The contents of Cu, Zn, Cr, Pb and Cd were rapid determined by atomic absorption spectrometry after decompression and constant volume. The effects of sample weight by microwave digestion, solvents and coexisting ions on analyzed results were discussed. The results showed that the determination was in accord with standard which is available for determination of Cu, Zn, Cr, Pb and Cd in modified feather.

  9. Photoluminescence study of ZnS and ZnS:Pb nanoparticles

    International Nuclear Information System (INIS)

    Photoluminescence (PL) study of pure and 5wt. % lead doped ZnS prepared by co-precipitation method was conducted at room temperature. The prepared nanoparticles were characterized by X-ray Diffraction (XRD), UV-Visible (UV-Vis) spectrophotometer, Photoluminescence (PL) and Raman spectroscopy. XRD patterns confirm cubic structure of ZnS and PbS in doped sample. The band gap energy value increased in case of Pb doped ZnS nanoparticles. The PL spectrum of pure ZnS was de-convoluted into two peaks centered at 399nm and 441nm which were attributed to defect states of ZnS. In doped sample, a shoulder peak at 389nm and a broad peak centered at 505nm were observed. This broad green emission peak originated due to Pb activated ZnS states

  10. Photoluminescence study of ZnS and ZnS:Pb nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Virpal,, E-mail: virpalsharma.sharma@gmail.com; Hastir, Anita; Kaur, Jasmeet; Singh, Gurpreet; Singh, Ravi Chand [Laboratory for Sensors and Physics Education, Department of Physics, Guru Nanak Dev University, Amritsar – 143005 (India)

    2015-05-15

    Photoluminescence (PL) study of pure and 5wt. % lead doped ZnS prepared by co-precipitation method was conducted at room temperature. The prepared nanoparticles were characterized by X-ray Diffraction (XRD), UV-Visible (UV-Vis) spectrophotometer, Photoluminescence (PL) and Raman spectroscopy. XRD patterns confirm cubic structure of ZnS and PbS in doped sample. The band gap energy value increased in case of Pb doped ZnS nanoparticles. The PL spectrum of pure ZnS was de-convoluted into two peaks centered at 399nm and 441nm which were attributed to defect states of ZnS. In doped sample, a shoulder peak at 389nm and a broad peak centered at 505nm were observed. This broad green emission peak originated due to Pb activated ZnS states.

  11. Photoluminescence study of ZnS and ZnS:Pb nanoparticles

    Science.gov (United States)

    Virpal, Hastir, Anita; Kaur, Jasmeet; Singh, Gurpreet; Singh, Ravi Chand

    2015-05-01

    Photoluminescence (PL) study of pure and 5wt. % lead doped ZnS prepared by co-precipitation method was conducted at room temperature. The prepared nanoparticles were characterized by X-ray Diffraction (XRD), UV-Visible (UV-Vis) spectrophotometer, Photoluminescence (PL) and Raman spectroscopy. XRD patterns confirm cubic structure of ZnS and PbS in doped sample. The band gap energy value increased in case of Pb doped ZnS nanoparticles. The PL spectrum of pure ZnS was de-convoluted into two peaks centered at 399nm and 441nm which were attributed to defect states of ZnS. In doped sample, a shoulder peak at 389nm and a broad peak centered at 505nm were observed. This broad green emission peak originated due to Pb activated ZnS states.

  12. Kinetic modeling and thermodynamic study to remove Pb(II), Cd(II), Ni(II) and Zn(II) from aqueous solution using dead and living Azolla filiculoides

    Energy Technology Data Exchange (ETDEWEB)

    Rakhshaee, Roohan [Department of Applied Chemistry, Faculty of Chemistry, Islamic Azad University, Rasht Branch, P.O. Box 41335-3516, Rasht (Iran, Islamic Republic of); Khosravi, Morteza [Department of Applied Chemistry, Faculty of Chemistry, Islamic Azad University, North Tehran Branch, P.O. Box 191367-4711, Tehran 191367-4711 (Iran, Islamic Republic of)]. E-mail: drm_khosravi@yahoo.com; Ganji, Masoud Taghi [Department of Applied Chemistry, Faculty of Chemistry, Islamic Azad University, North Tehran Branch, P.O. Box 191367-4711, Tehran 191367-4711 (Iran, Islamic Republic of)

    2006-06-30

    Dead Azolla filiculoides can remove Pb{sup 2+},Cd{sup 2+}, Ni{sup 2+} and Zn{sup 2+} corresponding to second-order kinetic model. The maximum adsorption capacity (Q {sub max}) to remove these metal ions by the alkali and CaCl{sub 2}/MgCl{sub 2}/NaCl (2:1:1, molar ratio) activated Azolla from 283 to 313 K was 1.431-1.272, 1.173-0.990, 1.365-1.198 and 1.291-0.981 mmol/g dry biomass, respectively. Q {sub max} to remove these heavy metals by the non-activated Azolla at the mentioned temperature range was obtained 1.131-0.977, 1.092-0.921, 1.212-0.931 and 1.103-0.923 mmol/g dry biomass, respectively. In order to remove these metal ions by the activated Azolla, the enthalpy change ({delta}H) was -4.403, -4.495, -4.557 and -4.365 kcal/mol and the entropy change ({delta}S) was 2.290, 1.268, 1.745 and 1.006 cal/mol K, respectively. While, to remove these metal ions by the non-activated Azolla, {delta}H was -3.685, -3.766, -3.967 and -3.731 kcal/mol and {delta}S was 2.440, 1.265, 1.036 and 0.933 cal/mol K, respectively. On the other hand, the living Azolla removed these heavy metals corresponding to first-order kinetic model. It was also shown that pH, temperature and photoperiod were effective both on the rate of Azolla growth and the rate of heavy metals uptake during 10 days. It was appeared the use of Ca(NO{sub 3}){sub 2} increased both Azolla growth rate and the rate of heavy metals uptake while the using KNO{sub 3} although increased Azolla growth rate but decreased the rate of heavy metals uptake.

  13. Assessment of soil contamination by potentially toxic trace elements (PTSD) (As, Cd, Cu, Hg, Pb, Zn) in a lower plain of the Hron River according to Law no. 219/2008 Coll., by geo-accumulation index, anthropogenic factor and Tomlinson index

    International Nuclear Information System (INIS)

    Soil contamination by different PTSD may have different geogenic and anthropogenic origin and occurs in all countries of the world. The aim of this paper is to evaluate the soils contamination of a lower plain of the Hron River. This paper used the results of the thesis Soil contamination of the Hron River floodplain by trace elements (As, Cd, Cu, Hg, Pb, Zn) [1]. Soil contamination was evaluated by: Act. 219/2008 Coll. on the protection and use of agricultural land, by anthropogenic factor (AF), geo-accumulation index (IgeoE) and Tomlinson index - the index of the pollution load (PLI). (author)

  14. Ethanol gas sensing by Zn-doped CdS/CdTe nanoparticles

    Science.gov (United States)

    Prabhu, M.; Manikandan, V. S.; Soundararajan, N.; Ramachandran, K.

    2016-05-01

    Zn-doped CdS/CdTe nanoparticles (NPs) were synthesized and studied here for gas sensing. The crystallographic properties of the samples were studied by X-ray diffraction (XRD), which shows cubic structure for CdS and CdTe NPs. The three longitudinal optical phonon modes at 298, 595 and 895 cm-1 were obtained from Raman spectrum and this also reveals the cubic structure of CdS NPs. The band gap for Zn-doped CdS/CdTe NPs increased slightly when compared with pure sample. The ethanol gas sensing in CdS/CdTe NPs shows an enhancement on Zn substitution.

  15. How phytohormone IAA and chelator EDTA affect lead uptake by Zn/Cd hyperaccumulator Picris divaricata.

    Science.gov (United States)

    Du, Rui-Jun; He, Er-Kai; Tang, Ye-Tao; Hu, Peng-Jie; Ying, Rong-Rong; Morel, Jean-Louis; Qiu, Rong-Liang

    2011-01-01

    In this paper, the effects of indole-3-acetic acid (IAA) and/or ethylenediaminetetraacetic acid (EDTA) on lead uptake by a Zn/Cd hyperaccumulator Picris divaricata were studied. P. divaricata responded to Pb by better root system and increased biomass in presence of phytohormone IAA, which was able to reduce the inhibiting effects of Pb on transpiration without reducing the uptake of Pb The application of 100 microM IAA increased plant transpiration rate by about 20% and Pb concentration in leaves by about 37.3% as compared to treatment exposed to Pb alone. The enhanced phytoextraction efficiency could be attributed to the mechanisms played by IAA through alleviating Pb toxicity, creating better root system and plant biomass, promoting a higher transpiration rate as well as regulating the level of nutrient elements. On the contrary, inefficiency of phytoextraction was found with EDTA or the combination of IAA and EDTA probably because most Pb was in the form of Pb-EDTA complex which blocked the uptake by P. divaricata. The present study demonstrated that IAA was able to enhance the phytoextraction of Pb by Zn/Cd hyperaccumulator P. divaricata, providing a feasible method for the phytoremediation of polymetallic contaminated soils. PMID:21972569

  16. Pb-Zn的电沉积及其多孔电极的制备%Pb-Zn Electrodeposition and Preparation of the Porous Pb-Zn Electrode

    Institute of Scientific and Technical Information of China (English)

    王森林; 李彩彩

    2012-01-01

    Due to the low melting point,high density,and higher over potential of hydrogen evolution reaction in acid solution,lead and its alloys were widely used in organic electrosynthesis.Porous Pb-Zn electrode was studied in this paper because the hardness of Pb-Zn coating was higher than that of pure Pb coating.The Pb-Zn coating was plated using a methylsulfonic acid bath,containing citrate and EDTA-2Na as a complexing agent.The cyclic voltammetry experiment and the cathode polarization showed that the Pb-Zn coating was deposited by step-by-step and was controlled by diffusion progress.The composition and structure of the Pb-Zn coating and its porous coating were studied by X-ray diffractometry(XRD),scanning electron microscopy(SEM) and X-ray energy dispersive spectroscopy(EDS),respectively.As a result,the Pb-Zn coating was formed by mixtures of Pb and Zn.After some Zn in the Pb-Zn coating was dissolved by 10vol% H2SO4,its surface grains become smaller,and the Pb-Zn coating was made into the porous Pb-Zn electrode.The less constant potential step experiment showed that the porous Pb-Zn electrode had a larger specific surface area.%铅基合金由于低熔点、高密度以及在酸性溶液中有较高析氢过电位等,被广泛应用于有机电合成中。由于Pb-Zn镀层的硬度较纯Pb高,本研究采用多孔Pb-Zn电极。在柠檬酸和EDTA-2Na为络合剂的甲磺酸镀液中电沉积出Pb-Zn镀层,循环伏安曲线和阴极极化曲线表明,Pb-Zn是分步沉积的,且均受扩散控制。采用X射线衍射、扫描电镜、能谱分析等研究了Pb-Zn镀层及其多孔电极组成和结构。结果表明,Pb-Zn镀层由Pb和Zn的混合物组成,Pb-Zn镀层用体积分数10%的H2SO4腐蚀后,Pb-Zn镀层表面晶粒细化,得到多孔Pb-Zn镀层。小幅度恒电位阶跃实验表明,多孔Pb-Zn电极具有更大的比表面积。

  17. The differentially-expressed proteome in Zn/Cd hyperaccumulator Arabis paniculata Franch. in response to Zn and Cd.

    Science.gov (United States)

    Zeng, Xiao-Wen; Qiu, Rong-Liang; Ying, Rong-Rong; Tang, Ye-Tao; Tang, Lu; Fang, Xiao-Hang

    2011-01-01

    The Zn/Cd hyperaccumulator Arabis paniculata is able to tolerate high level of Zn and Cd. To clarify the molecular basis of Zn and Cd tolerance, proteomic approaches were applied to identify proteins involved in Zn and Cd stress response in A. paniculata. Plants were exposed to both low and high Zn or Cd levels for 10 d. Proteins of leaves in each treatment were separated by 2-DE (two-dimensional electrophoresis). Nineteen differentially-expressed proteins upon Zn treatments and 18 proteins upon Cd treatments were observed. Seventeen out of 19 of Zn-responsive proteins and 16 out of 18 of Cd-responsive proteins were identified using MALDI-TOF/TOF-MS (matrix-assisted laser desorption/ionization time of flight mass spectrometry). The most of identified proteins were known to function in energy metabolism, xenobiotic/antioxidant defense, cellular metabolism, protein metabolism, suggesting the responses of A. paniculata to Zn and Cd share similar pathway to certain extend. However, the different metal defense was also revealed between Zn and Cd treatment in A. paniculata. These results indicated that A. paniculata against to Zn stress mainly by enhancement of energy metabolism including auxin biosynthesis and protein metabolism to maintain plant growth and correct misfolded proteins. In the case of Cd, plants adopted antioxidative/xenobiotic defense and cellular metabolism to keep cellular redox homeostasis and metal-transportation under Cd stress. PMID:21074242

  18. Extremely High Phosphate Sorption Capacity in Cu-Pb-Zn Mine Tailings

    Science.gov (United States)

    Huang, Longbin; Li, Xiaofang; Nguyen, Tuan A. H.

    2015-01-01

    Elevated inorganic phosphate (Pi) concentrations in pore water of amended tailings under direct revegetation may cause toxicity in some native woody species but not native forbs or herb species, all of which are key constituents in target native plant communities for phytostabilizing base metal mine tailings. As a result, Pi sorption capacity has been quantified by a conventional batch procedure in three types of base metal mine tailings sampled from two copper (Cu)-lead (Pb)-zinc (Zn) mines, as the basis for Pi-fertiliser addition. It was found that the Pi-sorption capacity in the tailings and local soil was extremely high, far higher than highly weathered agricultural soils in literature, but similar to those of volcanic ash soils. The Langmuir P-sorption maximum was up to 7.72, 4.12, 4.02 and 3.62 mg P g-1 tailings, in the fresh tailings of mixed Cu-Pb-Zn streams (MIMTD7), the weathered tailings of mixed Cu-Pb-Zn streams (MIMTD5), EHM-TD (fresh Cu-stream, high magnetite content) and local soil (weathered shale and schist), respectively. Physicochemical factors highly correlated with the high Pi-sorption in the tailings were fine particle distribution, oxalate and dithionite-citrate-bicarbonate extractable Fe (FeO and Fed), oxalate-extractable Al and Mn, and the levels of soluble Cd and Zn, and total S and Fe. Large amounts of amorphous Fe oxides and oxyhydroxides may have been formed from the oxidation of pyritic materials and redox cycles of Fe-minerals (such as pyrite (FeS2), ankerite (Ca(Fe Mg)(CO3)2 and siderite (FeCO3), as indicated by the extractable FeO values. The likely formation of sparingly soluble Zn-phosphate in the Pb-Zn tailings containing high levels of Zn (from sphalerite ((Zn,Fe)S, ZnS, (Zn,Cd)S)) may substantially lower soluble Zn levels in the tailings through high rates of Pi-fertiliser addition. As a result, the possibility of P-toxicity in native plant species caused by the addition of soluble phosphate fertilizers would be minimal. PMID

  19. Extremely High Phosphate Sorption Capacity in Cu-Pb-Zn Mine Tailings.

    Science.gov (United States)

    Huang, Longbin; Li, Xiaofang; Nguyen, Tuan A H

    2015-01-01

    Elevated inorganic phosphate (Pi) concentrations in pore water of amended tailings under direct revegetation may cause toxicity in some native woody species but not native forbs or herb species, all of which are key constituents in target native plant communities for phytostabilizing base metal mine tailings. As a result, Pi sorption capacity has been quantified by a conventional batch procedure in three types of base metal mine tailings sampled from two copper (Cu)-lead (Pb)-zinc (Zn) mines, as the basis for Pi-fertiliser addition. It was found that the Pi-sorption capacity in the tailings and local soil was extremely high, far higher than highly weathered agricultural soils in literature, but similar to those of volcanic ash soils. The Langmuir P-sorption maximum was up to 7.72, 4.12, 4.02 and 3.62 mg P g-1 tailings, in the fresh tailings of mixed Cu-Pb-Zn streams (MIMTD7), the weathered tailings of mixed Cu-Pb-Zn streams (MIMTD5), EHM-TD (fresh Cu-stream, high magnetite content) and local soil (weathered shale and schist), respectively. Physicochemical factors highly correlated with the high Pi-sorption in the tailings were fine particle distribution, oxalate and dithionite-citrate-bicarbonate extractable Fe (FeO and Fed), oxalate-extractable Al and Mn, and the levels of soluble Cd and Zn, and total S and Fe. Large amounts of amorphous Fe oxides and oxyhydroxides may have been formed from the oxidation of pyritic materials and redox cycles of Fe-minerals (such as pyrite (FeS2), ankerite (Ca(Fe Mg)(CO3)2 and siderite (FeCO3), as indicated by the extractable FeO values. The likely formation of sparingly soluble Zn-phosphate in the Pb-Zn tailings containing high levels of Zn (from sphalerite ((Zn,Fe)S, ZnS, (Zn,Cd)S)) may substantially lower soluble Zn levels in the tailings through high rates of Pi-fertiliser addition. As a result, the possibility of P-toxicity in native plant species caused by the addition of soluble phosphate fertilizers would be minimal. PMID

  20. Extremely High Phosphate Sorption Capacity in Cu-Pb-Zn Mine Tailings.

    Directory of Open Access Journals (Sweden)

    Longbin Huang

    Full Text Available Elevated inorganic phosphate (Pi concentrations in pore water of amended tailings under direct revegetation may cause toxicity in some native woody species but not native forbs or herb species, all of which are key constituents in target native plant communities for phytostabilizing base metal mine tailings. As a result, Pi sorption capacity has been quantified by a conventional batch procedure in three types of base metal mine tailings sampled from two copper (Cu-lead (Pb-zinc (Zn mines, as the basis for Pi-fertiliser addition. It was found that the Pi-sorption capacity in the tailings and local soil was extremely high, far higher than highly weathered agricultural soils in literature, but similar to those of volcanic ash soils. The Langmuir P-sorption maximum was up to 7.72, 4.12, 4.02 and 3.62 mg P g-1 tailings, in the fresh tailings of mixed Cu-Pb-Zn streams (MIMTD7, the weathered tailings of mixed Cu-Pb-Zn streams (MIMTD5, EHM-TD (fresh Cu-stream, high magnetite content and local soil (weathered shale and schist, respectively. Physicochemical factors highly correlated with the high Pi-sorption in the tailings were fine particle distribution, oxalate and dithionite-citrate-bicarbonate extractable Fe (FeO and Fed, oxalate-extractable Al and Mn, and the levels of soluble Cd and Zn, and total S and Fe. Large amounts of amorphous Fe oxides and oxyhydroxides may have been formed from the oxidation of pyritic materials and redox cycles of Fe-minerals (such as pyrite (FeS2, ankerite (Ca(Fe Mg(CO32 and siderite (FeCO3, as indicated by the extractable FeO values. The likely formation of sparingly soluble Zn-phosphate in the Pb-Zn tailings containing high levels of Zn (from sphalerite ((Zn,FeS, ZnS, (Zn,CdS may substantially lower soluble Zn levels in the tailings through high rates of Pi-fertiliser addition. As a result, the possibility of P-toxicity in native plant species caused by the addition of soluble phosphate fertilizers would be minimal.

  1. Characterization of thin film ZnCdS/CdTe solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Mahammad Hussain, O.; Sreedhara Reddy, P.; Srinivasalu Naidu, B.; Uthanna, S.; Jayarama Reddy, P. (Sri Venkateswara Univ., Tirupati (India). Dept. of Physics)

    1991-07-01

    n-ZnCdS/p-CdTe polycrystalline thin film solar cells were fabricated by laser evaporating CdTe onto sprayed ZnCdS films. The cells were characterized by studying current-voltage, capacitance-voltage and spectral response measurements. A maximum efficiency of 7.6% was observed for a cell area of 1 cm{sup 2}. (author).

  2. Localisation and quantification of elements within seeds of Cd/Zn hyperaccumulator Thlaspi praecox by micro-PIXE

    Energy Technology Data Exchange (ETDEWEB)

    Vogel-Mikus, Katarina [Department of Biology, Biotechnical Faculty, University of Ljubljana, Vecna pot 111, SI-1000 Ljubljana (Slovenia); Pongrac, Paula [Department of Biology, Biotechnical Faculty, University of Ljubljana, Vecna pot 111, SI-1000 Ljubljana (Slovenia); Kump, Peter [Jozef Stefan Institute, Jamova 39, SI-1000 Ljubljana (Slovenia); Necemer, Marijan [Jozef Stefan Institute, Jamova 39, SI-1000 Ljubljana (Slovenia); Simcic, Jure [Jozef Stefan Institute, Jamova 39, SI-1000 Ljubljana (Slovenia); Pelicon, Primoz [Jozef Stefan Institute, Jamova 39, SI-1000 Ljubljana (Slovenia); Budnar, Milos [Jozef Stefan Institute, Jamova 39, SI-1000 Ljubljana (Slovenia); Povh, Bogdan [Max-Planck-Institut fuer Kernphysik, P.O. Box 103980, 69029 Heidelberg (Germany); Regvar, Marjana [Department of Biology, Biotechnical Faculty, University of Ljubljana, Vecna pot 111, SI-1000 Ljubljana (Slovenia)]. E-mail: marjana.regvar@bf.uni-lj.si

    2007-05-15

    Cd, Zn and Pb accumulation, spatial distribution within seeds and germinating seedlings, and seeds fitness of metal hyperaccumulating Thlaspi praecox were investigated in order to gain more knowledge on plant reproductive success at metal polluted sites. The seeds contained up to 1351 {mu}g g{sup -1} (dry weight) of Cd, 121 {mu}g g{sup -1} of Zn and 17 {mu}g g{sup -1} of Pb. Seed fitness was negatively influenced by seed Cd hyperaccumulation. Nevertheless, the viability of seeds was decreased by maximally 20%, indicating very efficient tolerance of the plant embryos to Cd. Localisation by micro-PIXE revealed preferential storage of most elements in the embryonic axis. Cd and Zn were preferentially localised in the epidermis of cotyledons. The restriction of seed Pb and Zn uptake and hyperaccumulation of Cd, accompanied by partitioning of Cd in the epidermal tissues of cotyledons, may enable the survival of T. praecox embryos and seedlings in Cd polluted environments. - Hyperaccumulation of Cd with partitioning in the epidermis of cotyledons was observed in T. praecox embryos.

  3. Metal and metalloid contamination in roadside soil and wild rats around a Pb-Zn mine in Kabwe, Zambia

    International Nuclear Information System (INIS)

    Metal (Cr, Co, Cu, Zn, Cd, Pb, Ni) and metalloid (As) accumulation was studied in roadside soil and wild rat (Rattus sp.) samples from near a Pb-Zn mine (Kabwe, Zambia) and the capital city of Zambia (Lusaka). The concentrations of the seven metals and As in the soil samples and Pb in the rat tissue samples were quantified using atomic absorption spectroscopy. The concentrations of Pb, Zn, Cu, Cd, and As in Kabwe soil were much higher than benchmark values. Geographic Information System analysis indicated the source of metal pollution was mining and smelting activity. Interestingly, the area south of the mine was more highly contaminated even though the prevailing wind flow was westward. Wild rats from Kabwe had much higher tissue concentrations of Pb than those from Lusaka. Their body weight and renal Pb levels were negatively correlated, which suggests that mining activity might affect terrestrial animals in Kabwe. - The area around Kabwe, Zambia is highly polluted with metals and As. Wild rats from this area had high tissue concentrations of Pb and decreased body weight.

  4. Tunneling of spin polarized excitons in ZnCdSe and ZnCdMnSe coupled double quantum wells

    Energy Technology Data Exchange (ETDEWEB)

    Ohmori, Kenta; Kodama, Kazuki; Muranaka, Tsutomu; Nabetani, Yoichi; Matsumoto, Takashi [Department of Electrical and Electronic Engineering, University of Yamanashi, Takeda 4, Kofu 400-8511 (Japan)

    2010-06-15

    This paper describes an experiment on tunneling transfer of excitons in coupled DQW structures. DQW's consist of diluted magnetic semiconductor (DMS) (ZnCdMnSe) and non-DMS (ZnCdSe) well layers, separated by a non-DMS ZnSe barrier. The energy levels in ZnCdSe and ZnCdMnSe wells are adjusted by controlling layer thicknesses and compositions. Circular polarization selective photoluminescence (PL) and reflectance spectra are measured in magnetic fields perpendicular to the hetero-interface. Degree of circular polarization of PL from ZnCdSe well is changed by magnetic fields reflecting changes in degree of spin polarization in ZnCdSe well. The change depends on the strength of magnetic field and on the energy levels in the two wells. The polarization change is explained in terms of resonant tunneling of spin polarized carriers from zero-dimensional (0D) like state in ZnCdMnSe well to 0D like state in ZnCdSe well. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  5. 陕西省主产区主栽品种猕猴桃果实中Cu、Zn、Mn、Pb、Cd含量检测%Determination of Cu,Zn, Mn, Pb and Cd content of kiwifruit fruit of the main cultivars in the major kiwifruit production area of Shaanxi province

    Institute of Scientific and Technical Information of China (English)

    赵金梅; 段爱莉; 高贵田; 王西锐; 孙翔宇; 谷留杰

    2012-01-01

    The metal elements Cu, Mn,Zn, Pb and Cd of four varieties of kiwifruit collected from ten main producing areas of kiwifruit production base Jn ShaanxJ province were detected and analyzed respectively using flame atomic absorption spectrometric method.The results showed that the detection rate of Cu,Zn and Mn was 100% and Pb was 13.64%, but Cd was not detected in Shaanxi kiwifruit. Moreover, the content of Zn exceeded the national standard among all the samples while the content of the rest was lower than the limited amount of the national standard for fruits. The content of those varieties was highly of difference from variant varieties to different producing areas.Zn content exceeded seriously in partial samples of producing area No,2 as well as in parts of Qinmei kiwifruit.Attentions should be paid to the pollution resulting from Zn.%目的:采集陕西省猕猴桃生产基地的10个主产区中的4个品种猕猴桃果实,对其金属元素含量进行检测分析。方法:采用火焰原子吸收光谱法测定Cu、Mn、Zn、Pb、Cd5种金属元素的含量,并与国家标准进行比对和评价。结果:10个产区4个品种的猕猴桃果实中Cu、Mn、Zn的检出率均为100%,Pb检出率为13.64%,Cd未检出,在所有检出样品中仅Zn超标,其余均低于国家水果污染物限量标准。不同产地,不同品种中5种元素含量均有一定差异,其中2亏产区部分样品以及部分秦美猕猴桃Zn超标较为严重,Zn的污染需引起有关部门的重视。

  6. Effect of LuF3 on Stability and Infrared Property of 20GaF3-15InF3-20CdF2-15ZnF2-20PbF2-10SnF2 Glass%Lu3+掺杂对20GaF3-15InF3-20CdF2-15ZnF2-20PbF2-10SnF2玻璃抗析晶能力和红外吸收边的影响

    Institute of Scientific and Technical Information of China (English)

    朱基千; 李志国; 贺芸芬; 唐高; 白朝颖

    2005-01-01

    以20GaF3-15InF3-20CdG2-15ZnF2-20PbF2-10SnF2氟化镓玻璃为基玻璃,用LuF3替代等摩尔含量的PbF2,以改善玻璃的抗析晶能力.用差示扫描量热法研究了LuF3含量对玻璃热性能和抗析晶能力的影响,用红外透过光谱研究了LuF3含量对玻璃透红外性能的影响.结果表明:在玻璃中掺入摩尔分数为2%的LuF3可以获得最佳的抗析晶能力;LuF3的掺入对玻璃的透红外性能稍有影响,红外截止波长的变化范围仅在10.1μm~10.9μm之间.

  7. Kinetics of Evaporation of Zn and Pb from Carbon-bearing Pellets Made of Dust Containing Zn-Pb-Fe Oxides

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The influence of reduction temperature, size of coal powder and the carbon content on the evaporation rates of Zn and Pb in pellets made of ZnO-PbO-FeO bearing dust has been investigated between 1100€?1300℃. The evaporation rate of Zn and Pb obtained from the experiments has been analyzed with kinetic models. The results show that the control step for evaporation of Zn is reduction reaction of ZnO by CO at the interface,and that the evaporation rate of Pb is controlled by the volatilization of reduction products, i.e. liquid lead. The overall apparent activation energies of Zn and Pb evaporation from the pellet are 79.42kJ/mol and 88.74kJ/mol respectively.

  8. Mosses as indicators of atmospheric pollution of trace metals (Cd, Cu, Pb, Mn and Zn) in the vicinity of coal-fired brick kilns in north-eastern suburbs of Islamabad, Pakistan

    International Nuclear Information System (INIS)

    Determination of toxic elements Cd, Pb and other heavy metals has been carried out Rawalpindi - Islamabad region using the moss monitoring technique. The carpet moss samples (Hypnum Cupressiforme) were collected over an area of 196 km2 around lignite/coal-fired brick kilns for regular periods of time during 1997-1999. The elements were extracted into solution with multiacid digestion and then analyzed by atomic absorption spectrometry. The metal contents in moss samples from sites adjacent to coal-fired brick kilns was higher as compared to samples collected from the sites away from that sources. The results obtained by the 'BIOMONITORING' technique, for the first time in this area, are presented. (author)

  9. Characterization of cadmium biosorption by Exiguobacterium sp. isolated from farmland soil near Cu-Pb-Zn mine.

    Science.gov (United States)

    Park, Jin Hee; Chon, Hyo-Taek

    2016-06-01

    Bacteria have the ability to bind heavy metals on their cell wall. Biosorption is a passive and energy-independent mechanism to adsorb heavy metals. The efficiency of heavy metal biosorption can vary depending on several factors such as the growth phase of bacteria, solution pH, and existence of competitive heavy metals. In this study, Exiguobacterium sp. isolated from farmland soil near a mine site were used, and optimal conditions for Cd biosorption in solution were investigated. As bacterial growth progressed, Cd biosorption increased, which is attributed to changes in the structure and composition of the cell wall during bacterial growth. The biosorption process was rapid and was completed within 30 min. Cadmium biosorption was highest at pH 7 due to the dissociation of hydrogen ions and the increase of negative charges with increasing pH. In the mixed metal solution of Cd, Pb, and Zn, the amount of biosorption was in the order of Pb>Cd>Zn while in a single metal solution, the order was Cd≥Pb>Zn. The maximum adsorption capacity for Cd by the isolated bacteria was 15.6 mg/g biomass, which was calculated from the Langmuir isotherm model. Different adsorption efficiencies under various environmental conditions indicate that, to control metal mobility, the conditions for biosorption should be optimized before applying bacteria. The results showed that the isolated bacteria can be used to immobilize metals in metal-contaminated wastewater. PMID:26951224

  10. Gamma spectrometric characterization of various CdTe and CdZnTe detectors

    CERN Document Server

    Arlt, R; Sumah, P

    1999-01-01

    CdZnTe and CdTe detectors are now used by the Department of Safeguards of the International Atomic Energy Agency in significant numbers. To prepare, plan and support various verification methods, their properties must be well characterized and understood. In this paper we present some of the results which were obtained with large volume hemispheric CdZnTe detectors and high-resolution CdTe detectors.

  11. Mercaptopropionic acid capped CdSe/ZnS quantum dots as fluorescence probe for lead(II)

    International Nuclear Information System (INIS)

    MPA stabilized CdSe/ZnS NCs was applied as a fluorescent probe for the sensitive detection of Pb2+ in water. The microreaction was demonstrated as a facile method for the reproducible synthesis of CdSe/ZnS NCs with a high quantum yield. The good stability of CdSe/ZnS NCs was proved by the significant maintaining of photoluminescent (PL) after the ligand exchange with MPA, and was further demonstrated by the excellent PL property in water solution with various pH values. The cation exchange of Zn with Pb led to the linear quenching of PL with the concentration of Pb2+, which provided as an opportunity to apply MPA stabilized CdSe/ZnS NCs as fluorescent probes for Pb2+. A facile method by adjustment of QDs concentration was demonstrated as a suitable way to approach different detection limits. The detection limits of 0.03 and 3.3 μM were achieved by setting QDs solutions with the absorbance of the first exciton peak as 0.05 and 0.15, respectively.

  12. On the concentration and separation of the trace-elements fe, cu, zn, mn, pb, mo and co : Paper chromatography

    NARCIS (Netherlands)

    Erkelens, P.C. van

    1961-01-01

    Paper chromatographic separations are described by which the minor constituents of biological ashes are separated either into: (Pb) - Mn - Co - (Pb) - Cu - Fe, Mo, Zn; or into: Cu, Mn, Co - Pb - Fe - Mo - Zn.

  13. Optical behavior and sensor activity of Pb ions incorporated ZnO nanocrystals

    Science.gov (United States)

    Kannadasan, N.; Shanmugam, N.; Sathishkumar, K.; Cholan, S.; Ponnguzhali, R.; Viruthagiri, G.

    2015-05-01

    We present the synthesis and characterization of nanocrystalline ZnO doped with Pb in different concentrations. The structural and chemical compositions of the products are characterized by XRD, XPS, EDS and FT-IR spectroscopy. The observed results suggest that Pb ions (Pb2+ and Pb4+) are successfully incorporated into the lattice position of Zn2+ ions in ZnO. The optical properties of the products are studied by UV-Vis and room temperature PL measurements. The PL emission spectra of ZnO:Pb, show the intensity quenching for both the UV and visible emissions. The influence of Pb on controlling the size and morphology of ZnO is studied by FESEM and confirmed by HRTEM. Amperometric response shows that ZnO incorporated with 0.075 M of Pb ions has enhanced sensor activity for H2O2 than the undoped product.

  14. Characterization of CdTe, (Cd,Zn)Te, and Cd(Te,Se) single crystals by transmission electron microscopy

    Science.gov (United States)

    Rai, R. S.; Mahajan, S.; McDevitt, S.; Johnson, C. J.

    1991-10-01

    CdTe, (Cd,Zn)Te, and Cd(Te,Se) crystals grown by the Bridgman technique have been characterized by transmission electron microscopy. Results indicate that the Te precipitates are seen in all the crystals, but their density and size are lowest and largest in the case of Cd(Te,Se) crystals. In addition, dislocations, stacking faults, and microtwins are observed in as-grown CdTe, (Cd,Zn)Te, and Cd(Te,Se) crystals. Arguments have been developed to rationalize these observations and their ramifications on crystal perfection are discussed.

  15. Noise properties of Pb/Cd-free thick film resistors

    Science.gov (United States)

    Witold Stadler, Adam; Kolek, Andrzej; Zawiślak, Zbigniew; Mleczko, Krzysztof; Jakubowska, Małgorzata; Rafał Kiełbasiński, Konrad; Młożniak, Anna

    2010-07-01

    Low-frequency noise spectroscopy has been used to examine noise properties of Pb/Cd-free RuO2- and CaRuO3-based thick films screen printed on alumina substrates. Experiments were performed in the temperature range 77-300 K and the frequency range 0.5-5000 Hz with multiterminal devices. The measured noise has been recognized as resistance noise that consists of background 1/f noise and components generated by several thermally activated noise sources (TANSs) of different activation energies. The total noise has been composed of the contributions generated in the resistive layer and in the resistive/conductive layers interface. These noise sources are non-uniformly distributed in the resistor volume. Noise intensity of new-resistive layers has been described by the noise parameter Cbulk. Pb/Cd-free layers turned out to be noisier than their Pb-containing counterparts; however, the removal of Pb and Cd from resistive composition is hardly responsible for the increase in the noise. In the case of RuO2 layers noise increases most likely due to larger grain size of RuO2 powder used to prepare resistive pastes. Information on the quality of the resistive-to-conductive layers interface occurred to be stored in the values of noise parameter Cint. Pb/Cd-free RuO2-based resistive pastes form well-behaved interfaces with various Ag-based conductive pastes. In contrast, CaRuO3-based paste forms bad contacts with AgPd terminations because the density of TANSs increases in the interface area.

  16. Noise properties of Pb/Cd-free thick film resistors

    International Nuclear Information System (INIS)

    Low-frequency noise spectroscopy has been used to examine noise properties of Pb/Cd-free RuO2- and CaRuO3-based thick films screen printed on alumina substrates. Experiments were performed in the temperature range 77-300 K and the frequency range 0.5-5000 Hz with multiterminal devices. The measured noise has been recognized as resistance noise that consists of background 1/f noise and components generated by several thermally activated noise sources (TANSs) of different activation energies. The total noise has been composed of the contributions generated in the resistive layer and in the resistive/conductive layers interface. These noise sources are non-uniformly distributed in the resistor volume. Noise intensity of new-resistive layers has been described by the noise parameter Cbulk. Pb/Cd-free layers turned out to be noisier than their Pb-containing counterparts; however, the removal of Pb and Cd from resistive composition is hardly responsible for the increase in the noise. In the case of RuO2 layers noise increases most likely due to larger grain size of RuO2 powder used to prepare resistive pastes. Information on the quality of the resistive-to-conductive layers interface occurred to be stored in the values of noise parameter Cint. Pb/Cd-free RuO2-based resistive pastes form well-behaved interfaces with various Ag-based conductive pastes. In contrast, CaRuO3-based paste forms bad contacts with AgPd terminations because the density of TANSs increases in the interface area.

  17. Effect of the interface on UV-vis-IR photodetection performance of PbS/ZnO nanocomposite photocatalysts

    Science.gov (United States)

    Sun, Jie; Li, Yuanzhi; Yang, Yi; Bai, Jilin; Zhao, Xiujian

    2015-12-01

    Two PbS/ZnO nanocomposites with the same Pb/Zn molar ratio of 1:12 and different PbS/ZnO interface were prepared by depositing PbS nanocrystals on nano ZnO with the reaction between Pb(NO3)2 and Na2S through changing the sequence of adding Pb(NO3)2 and Na2S to the nano ZnO suspension: (A) first adding Pb(NO3)2 followed by adding Na2S (denoted PbS/ZnO-A); (B) first adding Na2S followed by adding Pb(NO3)2 (denoted PbS/ZnO-B). The PbS/ZnO nanocomposites are characterized by XRD, BET, Raman, TEM, XPS, and UV-vis-IR. The characterizations indicate that PbS/ZnO-A has an interface of PbS nanocrystal closely contacted to ZnO nanocrystal while PbS/ZnO-B has an interface of a disordered layer between PbS nanocrystal and ZnO nanocrystal. It is found for the first time that the PbS/ZnO interface plays an important role in their photodetection performance. PbS/ZnO-A exhibits much higher photoresponse current and lower rise and recovery time than both PbS/ZnO-B and a mixture of nano PbS and ZnO with the same Pb/Zn molar ratio as PbS/ZnO-A for visible and near-infrared photodetection. PL and the impedance measurement in dark and irradiation reveal that the superior photodetection performance of PbS/ZnO-A over PbS/ZnO-B is attributed to its lower e-h recombination and migration resistance under the irradiation of visible and infrared light due to its very good PbS/ZnO interface of PbS nanocrystals closely attached ZnO nanocrystals, through which photogenerated electrons inject efficiently from the conduction band of PbS to that of ZnO. In contrast, the defect sites in the disordered layer between PbS nanocrystal and ZnO nanocrystal for PbS/ZnO-B act as e-h recombination centers, significantly decreasing the e-h separation efficiency.

  18. Analysis of Etched CdZnTe Substrates

    Science.gov (United States)

    Benson, J. D.; Bubulac, L. O.; Jaime-Vasquez, M.; Lennon, C. M.; Arias, J. M.; Smith, P. J.; Jacobs, R. N.; Markunas, J. K.; Almeida, L. A.; Stoltz, A.; Wijewarnasuriya, P. S.; Peterson, J.; Reddy, M.; Jones, K.; Johnson, S. M.; Lofgreen, D. D.

    2016-06-01

    State-of-the-art as-received (112)B CdZnTe substrates have been examined for surface impurity contamination and polishing residue. Two 4 cm × 4 cm and one 6 cm × 6 cm (112)B state-of-the-art as-received CdZnTe wafers were analyzed. A maximum surface impurity concentration of Al = 1.7 × 1015 atoms cm-2, Si = 3.7 × 1013 atoms cm-2, Cl = 3.12 × 1015 atoms cm-2, S = 1.7 × 1014 atoms cm-2, P = 1.1 × 1014 atoms cm-2, Fe = 1.0 × 1013 atoms cm-2, Br = 1.2 × 1014 atoms cm-2, and Cu = 4 × 1012 atoms cm-2 was observed on the as-received CdZnTe wafers. CdZnTe particulates and residual SiO2 polishing grit were observed on the surface of the as-received (112)B CdZnTe substrates. The polishing grit/CdZnTe particulate density on CdZnTe wafers was observed to vary across a 6 cm × 6 cm wafer from ˜4 × 107 cm-2 to 2.5 × 108 cm-2. The surface impurity and damage layer of the (112)B CdZnTe wafers dictate that a molecular beam epitaxy (MBE) preparation etch is required. The contamination for one 4 cm × 4 cm and one 6 cm × 6 cm CdZnTe wafer after a standard MBE Br:methanol preparation etch procedure was also analyzed. A maximum surface impurity concentration of Al = 2.4 × 1015 atoms cm-2, Si = 4.0 × 1013 atoms cm-2, Cl = 7.5 × 1013 atoms cm-2, S = 4.4 × 1013 atoms cm-2, P = 9.8 × 1013 atoms cm-2, Fe = 1.0 × 1013 atoms cm-2, Br = 2.9 × 1014 atoms cm-2, and Cu = 5.2 × 1012 atoms cm-2 was observed on the MBE preparation-etched CdZnTe wafers. The MBE preparation-etched surface contamination consists of Cd(Zn)Te particles/flakes. No residual SiO2 polishing grit was observed on the (112)B surface.

  19. Lead zinc borate, PbZn2(BO3)2.

    Science.gov (United States)

    Chen, Xue An; Zhao, Ying Hua; Chang, Xin An; Zhang, Li; Xue, Hai Ping

    2006-01-01

    PbZn2(BO3)2 crystallizes in the space group Pccn, with the Pb cation at a site with imposed twofold symmetry. The compound represents a new structure type in which ZnBO3 layers are bridged by Pb2+ cations, giving rise to a three-dimensional framework. Channels parallel to the [010] direction accommodate the stereochemically active lone pairs of the Pb2+ cations. PMID:16397327

  20. Characterisation of vapour phase grown CdTe and (Cd,Zn)Te for detector applications

    CERN Document Server

    Fiederle, M; Rogalla, M; Meinhardt, J; Ludwig, J; Runge, K; Benz, W

    1999-01-01

    The growth of CdTe from the vapour phase offers several improvements in crystal quality and homogeneity. CdTe and (Cd, Zn)Te were grown by the modified Markov technique. The transport properties and the detector performance are given and compared to melt grown material. (author)

  1. Fabrication of pixelated CdTe and CdZnTe radiation detectors

    International Nuclear Information System (INIS)

    Cadmium telluride (CdTe) and cadmium zinc telluride (CdZnTe) are compound semiconductor characterized by wide semiconducting band gap and high photon stopping power due to its high atomic number and density. The mobility-life time product (μ t product) for holes in the materials is smaller than that for electrons. Hence, the effect of trapping losses is more pronounced on holes than on electrons. The trapping losses for holes limit achievable energy resolutions for planar detectors. In this study, pixelated CdTe detectors and pixelated CdZnTe detectors were fabricated and tested by 662 KeV gamma-rays of 137Cs at room temperature. Electrodes were formed on both sides of CdTe crystals and CdZnTe crystals by vacuum evaporation of gold. For purpose of comparison, a planar CdTe detector and a planar CdZnTe detector were evaluated. Since the pixelated CdTe detectors and the pixelated CdZnTe detectors operated as a single-polarity charge sensing device, the obtained energy resolutions were significantly higher than those for the planar detectors. Further improvement of energy resolutions of the detectors will be achieved by optimizing electrode structures. (M. Suetake)

  2. Soil-plant abstract of heavy metals in Pb-Zn mining sites from Alcudia Valley (South Spain)

    Science.gov (United States)

    López-Berdonces, Miguel; Higueras, Pablo; Esbrí, Jose Maria; González-Corrochano, Beatríz; García-Noguero, Eva Mª; Martínez-Coronado, Alba; Fernandez-Calderón, Sergio; García-Noguero, Carolina

    2013-04-01

    Soil-plant transfer of heavy metals in Pb-Zn mining sites from Alcudia Valley (South Spain). Authors: Miguel A. López-Berdonces¹; Pablo Higueras¹; Jose María Esbrí¹; Beatriz González-Corrochano¹; Eva Mª García- Noguero¹; Alba Martínez Coronado¹; Sergio Fernández-Calderón¹; Carolina García-Noguero¹ ¹Instituto de Geología Aplicada, Universidad Castilla la Mancha, Pza. Manuel Meca, 1. 13400 Almadén, Spain. Alcudia Valley is a vast territory recently declared Natural Park, located in South of Spain. It is an area rich in mineral deposits of Zn and Pb and mining exists since the first millennium BC., having its highest ore production between mid-nineteenth century and the middle of the twentieth. This area has been selected because has more than 120 abandoned mines without remediation actions, with dumps and tailings with high contents of zinc and lead sulfides, and Cu, Ag, Cd, As, Sb in minor concentrations. In this study we determinate the transfer rate of these metals from soils to plants represented by oak leaves (Quercus ilex), because this specie is common within the selected area. To evaluate the soil-plant transfer were studied the correlation of contents, total and extractable, in soil-leaves. Extractable fraction was done by for different methods in water, EPA 1312 sulfuric acid: nitric acid 60:40 v., Ammonium Acetate and EDTA. To establish the correlation between heavy metals from soils to plants is necessary to know the contents of these and bioavailable content in soil. Three areas (S. Quintín, Romanilla, Bombita) were selected, taking 24 samples of soils and leaves. Analyzed leaves by XRF showed that Mn, Pb, Zn and Mo in S.Quintin and Romanilla, Mn, Pb in Bombita, exceeded the toxicity threshold. The same samples analyzed by ICP show us the toxicity threshold is exceeded Pb, Zn and Hg in S.Quintin, and Pb in Romanilla. The heavy metal content in leaves compared between two techniques analytical gives an acceptable correlation Zn - Pb

  3. Effect of annealing temperature on the optical property of high Cd content CdZnO films

    Science.gov (United States)

    Liu, Teren; Wang, Dongbo; Guo, Fengyun; Jiao, Shujie; Wang, Jinzhong; Liu, Yuhang; Luan, Chunyang; Cao, Wenwu; Zhao, Liancheng

    2016-09-01

    CdZnO films with high Cd contents (59%) have been deposited on quartz substrate by radio-frequency (RF) magnetron sputtering. The as-deposited CdZnO films can hardly show detectable photoluminescence (PL). However, once subjected to suitable annealing temperature, the CdZnO films exhibit pronounced PL. Furthermore, when the annealing temperature at 300 °C and above, that the CdZnO are changed from the single phase of the rs structure to involving w, zb, and rs phases. Consequently, reliable formation and optical property improvement of the CdZnO layers are achieved through annealing temperature at 300 °C.

  4. Optical characterization of CdZnTe/CdTe strained quantum wells

    Energy Technology Data Exchange (ETDEWEB)

    Reno, J.L.; Jones, E.D.

    1990-01-01

    Strained layer structures have received a great deal of attention due both to their possible application in electronic devices and their intrinsic interest. The study of strained layer quantum wells grown using lattice mismatched materials has been widely developed for III-V semiconductors. Strained layer quantum wells grown using II-VI materials have not been studied nearly so much as those from III-V, but they are a rapidly growing field of semiconductor research. The wide gap II-VI materials are of interest because they are generally direct gap materials. This makes them attractive for optoelectronic devices. The majority of the work on strained layer structures in the wide gap tellurium based materials has focused in two areas. The first is the inclusion of Mn to produce dilute magnetic semiconductors (DMS) strained layers and superlattices. The other area is CdTe/ZnTe quantum wells and superlattices. Some related work has been done with CdZnTe/ZnTe structures. For the CdZnTe/CdTe very little work has been done and the majority of that used very small amounts of Zn. In this paper we will present the growth and optical characterization of Cd{sub 1-x}Zn{sub x}Te/CdTe strained single quantum wells (SSQW) where the Zn concentration ranges from about 10 to 50%. 10 refs., 3 figs.

  5. Geochemistry of the Patricia Zn-Pb-Ag Deposit (paguanta, NE Chile)

    Science.gov (United States)

    Chinchilla Benavides, D.; Merinero Palomares, R.; Piña García, R.; Ortega Menor, L.; Lunar Hernández, R.

    2013-12-01

    The Patricia Zn-Pb-Ag ore deposit is located within the Paguanta mining project, situated at the northern end of the Andean Oligocene Porphyry Copper Belt of Chile. The sulfide mineralization occurs as W-E oriented veins hosted in volcanic rocks, mainly andesite (pyroclastic, ash and lavas), of Upper Cretaceous to Middle Tertiary age. The ore mineralogy (obtained by EMPA analyses) comprises in order of abundance, pyrite, sphalerite (5.5 - 10.89 wt % Fe, 9.8-19 % molar FeS and 0.52 wt % Cd), galena, arsenopyrite, chalcopyrite and Ag-bearing sulfosalts. The veins show a zoned and banded internal structure with pyrite at the edges and sphalerite in the center. The Ag occurs mostly as Ag-Cu-Sb sulfosalts, in order of abundance: series freibergite - argentotennantite -polybasite and stephanite. Other minor Ag phases such as argentite, pyrargirite and diaphorite were also identified. These Ag phases are typically associated with the base-metal sulfides. Freibergite occurs filling voids within sphalerite, chalcopyrite and at the contact between sphalerite and galena. Polybasite, stephanite, pyrargirite and argentite are mostly in close association with freibergite. In the case of diaphorite, it commonly occurs filling voids between galena crystals or as inclusions within galena. Some minor Ag-bearing sulfosalts are also identified between pyrite crystals. The alteration minerals are dominated by chlorite, illite and kaolinite. The gangue minerals consist of quartz and carbonates identified by XRD as kutnahorite. We obtained linear correlation statistically significant only for Ag, As Au, Cd, Cu, Pb, Sb and Zn and therefore we generated an enhanced scatter plot matrix of these elements. Bulk rock analyses (ICP/MS and XRF) of drill cores show that Ag is strongly and positively correlated with Pb and As, moderately with Cd, Sb, Au and Zn and weakly with Cu, while Au is moderately and positively correlated with Ag, As, Cd, Sb and Zn and weakly with Cu and Pb. These results

  6. Optical properties of multicoated CdSe/CdS/ZnS quantum dots for multiphoton applications

    International Nuclear Information System (INIS)

    CdSe-core CdS/Cd0.5Zn0.5S/ZnS multishell quantum dots (QDs) were synthesized by using the successive ion layer adsorption and reaction method, and their optical properties were characterized experimentally. Based on probability calculations of the time-dependent Schroedinger equation, a kinetic Monte Carlo method was used to simulate and analyse the absorption and spontaneous emission spectra of multiphoton-excited QDs. It has been shown that the blue shift of the photoluminescence peak of the core CdSe QD after coating is most probably due to the Zn diffusion during the synthesis of the ZnS coating layer

  7. Lead and zinc poisoning and the interaction between Pb and Zn poisoning in the foal

    Energy Technology Data Exchange (ETDEWEB)

    Willoughby, R.A.; MacDonald, E.; McSherry, B.J.; Brown, G.

    1972-10-01

    Groups of young growing horses were fed toxic amounts of lead only, zinc only and the same amounts of lead and zinc together. Those fed Pb only developed pharyngeal and laryngeal paralysis (roaring) whereas those fed Zn only and Pb and Zn together developed the same clinical syndrome which included swelling at the epiphyseal region of the long bones, stiffness and lameness. Anemia and decreased weight gains were most pronounced in animals fed Zn for the longest periods. Animals fed Pb only did not become anemic and weight loss did not occur until after there was an interference in swallowing. The clinical signs and tissue Pb values from animals fed toxic amounts of both Pb and Zn continuously, differed markedly from those present in animals fed comparable amounts of Pb only. The clinical signs were similar to those caused by Zn poisoning. The hepatic and renal tissue Pb values were approximately twice as high and the epiphyseal and cancellous bone sample results were one half as high as the comparable Pb values from animals fed toxic amounts of Pb only. It appeared that toxic amounts of Zn prevented the development of clinical signs of Pb poisoning in the young growing horse. 30 references, 10 figures, 6 tables.

  8. [Stabilization Treatment of Pb and Zn in Contaminated Soils and Mechanism Studies].

    Science.gov (United States)

    Xie, Wei-qiang; Li, Xiao-mingi; Chen, Can; Chen, Xun-feng; Zhong, Yu; Zhong, Zhen-yu; Wan, Yong; Wang, Yan

    2015-12-01

    In the present work, the combined application of potassium dihydrogen phosphate, quick lime and potassium chloride was used to immobilize the Pb and Zn in contaminated soils. The efficiency of the process was evaluated through leaching tests and Tessier sequential extraction procedure. The mechanism of stabilization was analyzed by X-ray diffraction (XRD) and scanning electron microscope (SEM) to reveal the mechanism of stabilization. The results showed that the stabilizing efficiency of Pb contaminated soils was above 80% and the leaching concentrations of Pb, Zn were far below the threshold when the ratio of exogenous P and soil (mol · mol⁻¹) was 2:1-4: 1, the dosing ratio of CaO was 0.1%-0.5% ( mass fraction) and the dosage of potassium chloride was 0.02-0. 04 mol. Meanwhile, Pb and Zn in soil were transformed from the exchangeable fraction into residual fraction, which implied that the migration of Pb, Zn in soil could be confined by the stabilization treatment. XRD and SEM analysis revealed that Ca-P-Pb precipitation, lead orthophosphate [PbHP0₄, Pb₃ (PO₄)₂], pyromorphite (Pb-PO₄-Cl/OH) and mixed heavy metal deposits (Fe-PO₄- Ca-Pb-Zn-OH) could be formed after solidification/stabilization in which Pb and Zn could be wrapped up to form a solidified composition and to prevent leaching. PMID:27012000

  9. Impacts of Pb-Zn mining on Lake Kalimanci and Human Health in Eastern Macedonia

    Directory of Open Access Journals (Sweden)

    Vrhovnik P.

    2013-04-01

    Full Text Available Mining is very important economic activity. However, mining and related industries presents the main threat for environment. Pollution with heavy metals is a significant problem in Eastern Republic of Macedonia. In year 2003 great environmental disaster happened near small town Makedonska Kamenica, when the Sasa tailings dam collapsed and caused an intensive flow of mining waste material through Kamenica River valley and was discharged into Lake Klaimanci. Water from lake is used for irrigation, thus, the pollution assessment of the Lake Kalimanci sediments was made. The major, trace and rare earth element contamination in surficial lake sediments was studied to assess the effects of metalliferous mining activities. The mean concentrations of major elements [wt %] Si 23.5, Al 7.9, Fe 6.6, Mg 1.3, Ca 3.8, Na 1.1, K 2.3, Ti 0.4, P 0.2, Mn 0.6 and trace elements ranged within: Mo 1.0-4.6 mg kg-1, Cu 144.4-1162 mg kg-1, Pb 1874-16300 mg kg-1, Zn 2944-20900 mg kg-1, Ni 21.7-79.3 mg kg-1, Cd 16.5-136 mg kg-1, Sb 0.6-3.6 mg kg-1, Bi 3.0-24,3 mg kg-1 and Ag 1.4-17.3 mg kg-1. Results of rare earth elements (REE in surficial lake sediments indicated that are tightly related to the catchment geology. The results of the sequential extraction procedure revealed the majority (Cd, Zn, Pb, Ni, Cu and Cd of investigated toxic metals and all REEs to be strongly bonded to the exchangeable fraction and the rest (As and Mo to the oxidizable fraction. Regarding to results is evident that heavy metals and REEs are highly bioavailable for living organisms and can seriously affect human health.

  10. Photoluminescence study of the substitution of Cd by Zn during the growth by atomic layer epitaxy of alternate CdSe and ZnSe monolayers

    Energy Technology Data Exchange (ETDEWEB)

    Hernández-Calderón, I. [Physics Department,Cinvestav, Ave. IPN2508, 07360, México City, DF. (Mexico); Salcedo-Reyes, J. C. [Thin Films Group, Physics Department, Pontificia Universidad Javeriana, Cr. 7 No. 43-82, Ed. 53, Lab. 404, Bogotá, D.C. (Colombia)

    2014-05-15

    We present a study of the substitution of Cd atoms by Zn atoms during the growth of alternate ZnSe and CdSe compound monolayers (ML) by atomic layer epitaxy (ALE) as a function of substrate temperature. Samples contained two quantum wells (QWs), each one made of alternate CdSe and ZnSe monolayers with total thickness of 12 ML but different growth parameters. The QWs were studied by low temperature photoluminescence (PL) spectroscopy. We show that the Cd content of underlying CdSe layers is affected by the exposure of the quantum well film to the Zn flux during the growth of ZnSe monolayers. The amount of Cd of the quantum well film decreases with higher exposures to the Zn flux. A brief discussion about the difficulties to grow the Zn{sub 0.5}Cd{sub 0.5}Se ordered alloy (CuAu-I type) by ALE is presented.

  11. Photoluminescence study of the substitution of Cd by Zn during the growth by atomic layer epitaxy of alternate CdSe and ZnSe monolayers

    International Nuclear Information System (INIS)

    We present a study of the substitution of Cd atoms by Zn atoms during the growth of alternate ZnSe and CdSe compound monolayers (ML) by atomic layer epitaxy (ALE) as a function of substrate temperature. Samples contained two quantum wells (QWs), each one made of alternate CdSe and ZnSe monolayers with total thickness of 12 ML but different growth parameters. The QWs were studied by low temperature photoluminescence (PL) spectroscopy. We show that the Cd content of underlying CdSe layers is affected by the exposure of the quantum well film to the Zn flux during the growth of ZnSe monolayers. The amount of Cd of the quantum well film decreases with higher exposures to the Zn flux. A brief discussion about the difficulties to grow the Zn0.5Cd0.5Se ordered alloy (CuAu-I type) by ALE is presented

  12. Photoluminescence characteristics of Pb-doped, molecular-beam-epitaxy grown ZnSe crystal layers

    International Nuclear Information System (INIS)

    The characteristic green photoluminescence emission and related phenomena in Pb-doped, molecular-beam-epitaxy (MBE)-grown ZnSe crystal layers were investigated to explore the nature of the center responsible for the green emission. The intensity of the green emission showed a distinct nonlinear dependence on excitation intensity. Pb-diffused polycrystalline ZnSe was similarly examined for comparison. The characteristic green emission has been observed only in MBE-grown ZnSe crystal layers with moderate Pb doping. The results of the investigations on the growth conditions, luminescence, and related properties of the ZnSe crystal layers suggest that the green emission is due to isolated Pb replacing Zn and surrounded with regular ZnSe lattice with a high perfection

  13. CdS and CdS/CdSe sensitized ZnO nanorod array solar cells prepared by a solution ions exchange process

    International Nuclear Information System (INIS)

    Graphical abstract: - Highlights: • CdS and CdS/CdSe quantum dots are assembled on ZnO nanorods by ion exchange process. • The CdS/CdSe sensitization of ZnO effectively extends the absorption spectrum. • The performance of ZnO/CdS/CdSe cell is improved by extending absorption spectrum. - Abstract: In this paper, cadmium sulfide (CdS) and cadmium sulfide/cadmium selenide (CdS/CdSe) quantum dots (QDs) are assembled onto ZnO nanorod arrays by a solution ion exchange process for QD-sensitized solar cell application. The morphology, composition and absorption properties of different photoanodes were characterized with scanning electron microscope, transmission electron microscope, energy-dispersive X-ray spectrum and Raman spectrum in detail. It is shown that conformal and uniform CdS and CdS/CdSe shells can grow on ZnO nanorod cores. Quantum dot sensitized solar cells based on ZnO/CdS and ZnO/CdS/CdSe nanocable arrays were assembled with gold counter electrode and polysulfide electrolyte solution. The CdS/CdSe sensitization of ZnO can effectively extend the absorption spectrum up to 650 nm, which has a remarkable impact on the performance of a photovoltaic device by extending the absorption spectrum. Preliminary results show one fourth improvement in solar cell efficiency

  14. Effect of Cd,Pb Stress on the Activated Oxygen Scavenging System in Tobacco Levves

    Institute of Scientific and Technical Information of China (English)

    严重玲; 洪业汤; 等

    1998-01-01

    The effect of Cd,Pb stress on the activated oxygen scavenging system indicates that the content of chlorophyll.chlorophyll a/b ratio and the activity of CAT gradually decrease,the activity of SOD increases first and then decreases,and the activity of POd Gradually in creases with incrasing concentrations of Cd and Pb,Between Cd and Pb there is synergism in the Activated oxygen scavenging system.The results show that the stress of Cd and Pb can affect the scavenging system of activated oxygen and result in imbalance of activated oxygen metabolism.

  15. Synthesis and spectroscopic investigations of Cu- and Pb-doped colloidal ZnS nanocrystals.

    Science.gov (United States)

    Ehlert, Oliver; Osvet, Andres; Batentschuk, Miroslaw; Winnacker, Albrecht; Nann, Thomas

    2006-11-23

    A novel organometallic synthesis method for the preparation of colloidal ZnS nanoparticles is presented. This method enables the synthesis of undoped ZnS nanocrystals as well as doping with Cu, Pb, or both. The particles can be covered with an undoped layer of ZnS, forming core/shell-type particles with the ZnS:Pb, ZnS:Cu, or ZnS:Cu,Pb cores. The particles were characterized via TEM, XRD, dynamic light scattering, and optical spectroscopy. We investigated the extrinsic surface defects and their coverage with an additional ZnS layer in detail by temperature-dependent luminescence and luminescence lifetime spectroscopy. PMID:17107162

  16. Indoor stability tests on CdS/CdTe/ZnTe n-i-p submodules

    Energy Technology Data Exchange (ETDEWEB)

    Ramanathan, V.; Russell, L.A.; Liu, C.H.; Meyers, P.V. (Ametek Applied Materials Lab., Harleysville, PA (USA))

    1990-02-01

    Progress in the development of solar modules of the n-i-p CdS/CdTe/ZnTe structure is reported. By a combination of laser and mechanical scribing steps, several submodules were produced on 3 in x 6 in substrates. Results of the indoor stability tests show that the submodules are stable after 1500 h of exposure. (orig.).

  17. Fabrication and study of superconducting Pb and Zn nanowires

    Science.gov (United States)

    Kumar, Nitesh; Tian, Mingliang; Wang, Jinguo; Xu, Sheng-Yong; Mallouk, Thomas E.; Chan, Moses H. W.

    2004-03-01

    Superconducting nanowires of Pb and Zn were fabricated by electrochemical deposition in porous polycarbonate and alumina membranes. Morphology of the nanowires can be controlled by changing the deposition parameters, resulting in single-crystal, polycrystalline and nano-cluster wires. The diameter of the wires was in the range of 20-70 nm with the length ranging from 6-40 μm. The electrical resistivity measurements were done with respect to temperature, magnetic field and the excitation current using two-point measurement technique. Different superconducting materials were used as leads for the resistivity measurements. It was observed that superconducting leads have considerable effect on the superconducting properties of the nanowires. This work was supported by Penn State MRSEC NSF grant DMR 0213623.

  18. Organic acids inhibit the formation of pyromorphite and Zn-phosphate in phosphorous amended Pb- and Zn-contaminated soil.

    Science.gov (United States)

    Debela, F; Arocena, J M; Thring, R W; Whitcombe, T

    2013-02-15

    Pyromorphite (PY) and some zinc phosphates (Zn-P) are very sparingly soluble minerals and hence can immobilize Pb and Zn in contaminated soils. However, mechanisms leading to the poor efficiency of PY and Zn-P formation in contaminated soils amended with P still remain unclear. We studied the influence of two low molecular weight organic acids (LMWOA) - oxalic acid and citric acid and diethylene triamine pentaacetic acid (DTPA) - in PY and Zn-P formation in a P-amended contaminated soil. Despite the high levels of metals (∼4% Pb and 21% Zn) in the study soil, the addition of up to 1% inorganic P transformed only up to 37% and 17% of the total Pb and Zn to PY and Zn-P, respectively. Semi-quantitative estimates from a linear combination fitting of X-ray absorption near edge spectra (LC-XANES fitting) showed that the formation of PY decreased from 37% to 3% of the total Pb in the presence of oxalic acid and the addition of 1% P. The reduced PY formation may be associated with the increase in organic-bound Pb from 9% to 54% and decrease in carbonate associated Pb from 42% to 12% with oxalic acid addition as indicated by a chemical sequential extraction (SE) technique. Citric acid seemed to have a less adverse effect in PY formation than oxalic acid. Our data also suggests both oxalic and citric acids have less adverse effects on the efficiency of Zn-P formation. From this study we conclude that the abundance of LMWOA in soil environments can be one factor contributing to the poor efficiency of P amendments practices to effectively immobilize Pb and Zn in metal contaminated soils. PMID:23313859

  19. Characterization of thin film ZnCdS/CdTe solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Hussain, O.M.; Reddy, P.S.; Naidu, B.S.; Uthanna, S.; Reddy, P.J. (Sri Venkateswara Univ., Tirupati (IN). Dept. of Physics)

    1991-11-01

    Thin films of II-VI compound semiconductors have attracted considerable interest in recent years due to their wide range of applications in the fabrication of cost effective solar cells. Among these, cadmium telluride is one of the most attractive candidates with a direct band gap of 1.5 eV which is optimum for solar energy conversion. Generally, n-CdS is used as window layer to p-CdTe to fabricate heterojunction solar cells because of its reasonable optical transparency and the ease of depositing low-resistivity films. n-ZnCdS/p-CdTe polycrystalline thin film solar cells were fabricated by laser evaporating CdTe onto sprayed ZnCdS films. The cells were characterized by studying current-voltage, capacitance-voltage and spectral response measurements. A maximum efficiency of 7.6% was observed for a cell area of 1 cm{sup 2}. (author).

  20. Overcoming Zn segregation in CdZnTe with the temperature gradient annealing

    Science.gov (United States)

    Kim, K.; Bolotnikov, A. E.; Camarda, G. S.; Hossain, A.; James, R. B.

    2016-05-01

    The availability of large volume crystals with the same energy gap in melt-grown CdZnTe (CZT) is restricted due to the Zn segregation in CdTe hosts. We observed the migration of Zn in the solid phase along the positive temperature gradient direction both in situ and post-growth temperature gradient annealing (TGA) of CZT. Diffusivity of Zn obtained from the in situ TGA was approximately 10-5 cm2/s order and completely different mechanism with that of post-growth. The CZT ingots obtained through in situ TGA have uniform Zn and resistivity of 1010 Ω cm orders. The CZT detectors fabricated from in situ TGA applied ingots exhibit 10% of energy resolution for 59.5 keV peak of 241Am.

  1. Effects of Cd and Pb pollution on soil enzymatic activities and soil microbiota

    Institute of Scientific and Technical Information of China (English)

    LIU Shuqing; YANG Zhixin; WANG Xiaomin; ZHANG Xiaogui; GAO Rutai; LIU Xia

    2007-01-01

    Based on a representative sampling method and pot experiment with different concentrations of Cd and Pd,the enzymatic activities(urease,phosphatase,catalase,invertase),population of bacteria,fungus and actinomycete in the soil,the Cd and Pd pollution status of soil samples(from the wastewater-irrigated area of Baoding suburb)were appraised.Unitary linear and nonlinear curve-fitting optimization models were applied in the research,and the relationship between Pb and Cd causing pollution and enzymatic activities of the tested soils were discussed.The research may provide a theoretical basis for protecting the environment in the region of Baiyangdian Lake,Hebei province,prevent soil pollution,and ascertain biochemical indexes,which reflect soil heavy metal pollution levels.The research results indicated that:(1)there was obvious accumulation of Pb and Cd in the wastewater-irrigated area,also the accumulation in wastewater-irrigated soil is more than that in fresh water-irrigated soil,and accumulation on surface layer was more than that in the lower layer.Pb and Cd contents in the tested soils exceeded the standards of soil background values for some major cities at home and abroad and the world soil Cd and Pb contents range.This means that the tested soil had reached a lightly polluted level;(2)there existed an obvious negative correlation between soil enzymatic activities and Pb and Cd contents in wastewaterirrigated soil,where the soil urease and catalase activities decreased obviously with the increase of Pb and Cd contents in soil.Therefore,the urease and catalase can be considered as biochemical indexes that reflect the degree of soil Pb and Cd pollution;(3)the pot experiments indicated that the influence of Cd on soil enzymatic activities was greater than that of Pb.Generally,the effect of Cd on soil phosphatase,urease,catalase is more obvious than that on invertase,while Pb has a more obvious effect on invertase than Cd;(4)pot experiments of triple cropping

  2. The properties of CdTe solar cells with ZnTe/ZnTe: Cu buffer layers

    Institute of Scientific and Technical Information of China (English)

    Song Huijin; Zheng Jiagui; Feng Lianghuan; Yan Qiang; Lei Zhi; Wu Lili; Zhang Jingquan; Li Wei; Li Bing

    2008-01-01

    CdS/CdTe solar cells with ZnTe/ZnTe:Cu buffer layers were fabricated and studied. The energy band structure of it was analyzed. The C-V, I-V characteristics and the spectral response show that the ZnTe/ZnTe:Cu buffer layers improve the back contact characteristic properties, the diode characteristics of the forward junction and the short-wave spectral response of the CdTe solar cells. The ZnTe/ZnTe:Cu buffer layers affect the solar cell conversion efficiency and its fill factor.

  3. Gomphrena claussenii, a Zn and Cd hyperbioindicator species

    NARCIS (Netherlands)

    Tomaz Villafort Carvalho, M.

    2016-01-01

    Gomphrena claussenii, a Zn and Cd hyperbioindicator species

    A small group of plant species called metallophytes have evolved the ability to grow in highly metal-enriched soils that are toxic to other plants. Some of these metal-tolerant species have evolved the ability to accumulate high le

  4. The Summarization of Passivation Techniques on CdTe and CdZnTe Room-tempreture Detectors%CdTe和CdZnTe室温探测器钝化方法概述

    Institute of Scientific and Technical Information of China (English)

    赵晓燕; 鲁正雄

    2005-01-01

    CdTe和CdZnTe是X射线和γ射线探测器最理想的材料.钝化可以降低CdTe和CdZnTe的表面漏电流,提高其能量分辨率.本文综述了CdTe和CdZnTe的H2O2湿法钝化方法和热氧化、氧离子钝化、氧离子/SiNx钝化等干法钝化方法.

  5. Investigation of polycrystalline CdZnTe, CdMnTe, and CdTe films for photovoltaic applications

    Energy Technology Data Exchange (ETDEWEB)

    Rohatgi, A.; Ringel, S.A.; Sudharsanan, R. (School of Electrical Engineering, Georgia Inst. of Tech., Atlanta, GA (USA)); Meyers, P.V.; Liu, C.H.; Ramanthan, V. (Ametek Applied Materials Lab., Harleysville, PA (USA))

    1989-10-15

    Polycrystalline thin films of CdZnTe and CdMnTe have been grown by molecular beam epitaxy and metal-organic chemical vapor deposition, respectively, on CdS/SnO{sub 2}/glass substrates, with bandgaps of 1.65-1.75 eV for the top of a two-cell tandem design. P-i-n cells were fabricated and tested using Ni/p{sup +}-ZnTe as a back contact to the ternary films. CdTe cells were also fabricated using both growth techniques, which resulted in 9-10% efficiency and provided a baseline for ternary cell development. It was found that standard CdTe processing (400deg C air annealing) reduces the ternary bandgaps from about 1.7 to about 1.55 eV, resulting in significantly reduced subgap transmission with cell efficiencies of 3-4%. Optimum air-annealing conditions were determined to retain the 1.7 eV bandgaps; however, the cell performance was still limited by both poor CdZnTe/CdS interface quality and high series resistance. The junction interface was found to improve by annealing in the presence of hydrogen, which resulted in V{sub oc} values from 0.500 V to as high as 0.65 V, but the cell performance became increasingly limited by series resistance. The effects of cell processing on the properties of the CdZnTe/CdS interface, the bulk CdZnTe film, and the back-contact region have been investigated to provide guidelines for achieving high efficiency in widegap ternary cells. (orig.).

  6. Synthesis of CdSe/ZnS and CdTe/ZnS Quantum Dots: Refined Digestive Ripening

    International Nuclear Information System (INIS)

    We report synthesis of CdSe and CdTe quantum dots (QDs) from the bulk CdSe and CdTe material by evaporation/co-condensation using the solvated metal atom dispersion (SMAD) technique and refined digestive ripening. The outcomes of this new process are (1) the reduction of digestive ripening time by employing ligands (trioctylphosphine oxide (TOPO) and oleylamine (OA)) as capping agent as well as digestive ripening solvent, (2) ability to tune the photoluminescence (PL) from 410 nm to 670 nm, (3) demonstrate the ability of SMAD synthesis technique for other semiconductors (CdTe), (4) direct comparison of CdSe QDs growth with CdTe QDs growth based on digestive ripening times, and (5) enhanced PL quantum yield (QY) of CdSe QDs and CdTe QDs upon covering with a ZnS shell. Further, the merit of this synthesis is the use of bulk CdSe and CdTe as the starting materials, which avoids usage of toxic organometallic compounds, eliminates the hot injection procedure, and size selective precipitation processes. It also allows the possibility of scale up. These QDs were characterized by UV-vis, photoluminescence (PL), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and powder XRD.

  7. Synthesis of CdSe/ZnS and CdTe/ZnS Quantum Dots: Refined Digestive Ripening

    Directory of Open Access Journals (Sweden)

    Sreeram Cingarapu

    2012-01-01

    Full Text Available We report synthesis of CdSe and CdTe quantum dots (QDs from the bulk CdSe and CdTe material by evaporation/co-condensation using the solvated metal atom dispersion (SMAD technique and refined digestive ripening. The outcomes of this new process are (1 the reduction of digestive ripening time by employing ligands (trioctylphosphine oxide (TOPO and oleylamine (OA as capping agent as well as digestive ripening solvent, (2 ability to tune the photoluminescence (PL from 410 nm to 670 nm, (3 demonstrate the ability of SMAD synthesis technique for other semiconductors (CdTe, (4 direct comparison of CdSe QDs growth with CdTe QDs growth based on digestive ripening times, and (5 enhanced PL quantum yield (QY of CdSe QDs and CdTe QDs upon covering with a ZnS shell. Further, the merit of this synthesis is the use of bulk CdSe and CdTe as the starting materials, which avoids usage of toxic organometallic compounds, eliminates the hot injection procedure, and size selective precipitation processes. It also allows the possibility of scale up. These QDs were characterized by UV-vis, photoluminescence (PL, transmission electron microscopy (TEM, high-resolution transmission electron microscopy (HRTEM, X-ray photoelectron spectroscopy (XPS, and powder XRD.

  8. Fabrication of high-quality ZnCdO epilayers and ZnO/ZnCdO heterojunction on sapphire substrates by pulsed laser deposition

    Energy Technology Data Exchange (ETDEWEB)

    Yao, Gang, E-mail: yaogang1257@163.com [School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010 (China); College of Physics and Electronic Engineering, Leshan Normal University, Leshan 614004 (China); Tang, Yunqin [College of Physics and Electronic Engineering, Leshan Normal University, Leshan 614004 (China); Fu, Yajun; Jiang, Zhongqian [School of Materials Science and Engineering, Southwest University of Science and Technology, Mianyang 621010 (China); An, Xinyou [Department of Physics and Electronic Information, China West Normal University, Nanchong 637002 (China); Chen, Yu [College of Science, Inner Mongolia University of Technology, Hohhot 010051 (China); Liu, Yiding [College of Physics and Electronic Engineering, Leshan Normal University, Leshan 614004 (China)

    2015-01-30

    Highlights: • Zn{sub 1−x}Cd{sub x}O (0 ≤ x ≤ 9.60 at.%) thin films oriented along c-axis have been deposited on c-Al{sub 2}O{sub 3} substrates by PLD. • A band gap of 2.949 eV at room temperature has been achieved. • The relation between E{sub g} of Zn{sub 1−x}Cd{sub x}O system and x was expressed by E{sub g}(x) = 1.023 × 10{sup −4}x{sup 2}−0.034x + 3.253 (0 at.% ≤ x ≤ 100 at.%) according to the corrected first principles calculations. • ZnO/Zn{sub 1−x}Cd{sub x}O (x = 9.60 at.%) heterojunction has a type-I band alignment with a VBO of 0.203 eV. - Abstract: ZnCdO is a promising partner of ZnO to form ZnO/ZnCdO heterojunction and quantum wells. High-quality Zn{sub 1−x}Cd{sub x}O (0 ≤ x ≤ 9.60 at.%) films have been grown on c-plane sapphire substrates by pulsed laser deposition. XRD pattern confirmed all the ZnCdO films are of single hexagonal phase oriented along c-axis. A band gap of 2.949 eV at room temperature has been achieved. The relation between band gap of Zn{sub 1−x}Cd{sub x}O system and Cd content x was expressed by E{sub g}(x) = 1.023 × 10{sup −4} x{sup 2}−0.034x + 3.253 (0 at.% ≤ x ≤ 100 at.%) according to the corrected first principles calculations. Furthermore, band offsets of ZnO/Zn{sub 1−x}Cd{sub x}O (x = 9.60 at.%) heterojunction were characterized by X-ray photoelectron spectroscopy and valence-band offset of 0.203 eV was measured. A conduction-band offset of approximately 0.110 eV could be inferred from the measured valence-band offset. It is found that a type-I alignment takes place at the interface. The accurate determination of the band alignment of ZnO/Zn{sub 1−x}Cd{sub x}O heterojunction facilitates the design of optical and electronic devices based on ZnO/Zn{sub 1−x}Cd{sub x}O.

  9. Heavy metals and health risk assessment of arable soils and food crops around Pb-Zn mining localities in Enyigba, southeastern Nigeria

    Science.gov (United States)

    Obiora, Smart C.; Chukwu, Anthony; Davies, Theophilus C.

    2016-04-01

    This study determined the heavy metals concentration in arable soils and associated food crops around the Pb-Zn mines in Enyigba, Nigeria, and metal transfer factors were calculated. Air-dried samples of the soils and food crops were analyzed for 8 known nutritional and toxic heavy metals by Inductively Coupled Plasma - Mass Spectrometer (ICP-MS) method. Eighty seven percent of all the 20 sampled soils contain Pb in excess of the maximum allowable concentration (MAC) set by Canadian Environmental Quality Guideline (CCME) and European Union (EU) Standard, while Zn in thirty-one percent of the samples exceeded the CCME for MAC of 200 mg/kg. All the food crops, with the exception of yam tuber, contain Pb which exceeded the 0.43 mg/kg and 0.3 mg/kg MAC standards of EU and WHO/FAO respectively, with the leafy vegetables accumulating more Pb than the tubers. The metal transfer factors in the tubers and the leafy vegetables were in the order: Mo > Cu > Zn > Mn > As > Cd > Cr > Ni > Pb and Cd > Cu > Zn > Mn > Mo > As > Ni > Pb > Cr, respectively. Risk assessment studies revealed no health risk in surrounding populations for most of the heavy metals. However, Pb had a high health risk index (HRI) of 1.1 and 1.3, in adults and children, respectively for cassava tuber; Pb had HRI > 1 in lemon grass while Mn also had HRI > 1 in all the leafy vegetables for both adult and children. This high level of HRI for Pb and Mn is an indication that consumers of the food crops contaminated by these metals are at risk of health problems such as Alzheimers' disease and Manganism, associated with excessive intake of these metals. Further systematic monitoring of heavy metal fluxes in cultivable soils around the area of these mines is recommended.

  10. The potential of Lumbricus rubellus as a bioaccumulator of excess Pb and Cd in organic media

    Directory of Open Access Journals (Sweden)

    M. Arifin

    2015-07-01

    Full Text Available Lead (Pb and cadmium (Cd are sources of serious problems in the environment due to their reactivity and toxicity. Lumbricus rubellus is an earthworm reared by people is expected to reduce Pb and Cd concentrations in the environments. The aim of this study was to explore the ability of Lumbricus rubellus in reducing excess of Pb and Cd in organic media generated from urban waste. Sixteen treatments (four levels of Pb concentration and four levels of Cd concentration were arranged in a completely randomized design with three replications. Each treatment was placed in a wooden pot of 20 cm x 20 cm x 25 cm, and supplied with 40 Lumbricus rubellus for 30 days. Results of this study showed that 20 and 40% of the earthworm could survive until day 30 in organic media contaminated with Pb and Cd, respectively. Pb accumulated in the earthworm bodies ranged from 0.03 to 211.42 mg/kg, while the Cd accumulated in the earthworm body ranged from 0.57 to 22.11 mg/kg. The bioaccumulation factor for Pb was 46.98%, while that of Cd was 53.83%t. The content of Pb in vermicompost ranged from 0.04 to 19.41 mg/kg, while that of Cd ranged from 0.01 to 1.58 mg/kg.

  11. Flux flow and proximity effects in aligned Pb--Cd eutectic lamellar structures

    International Nuclear Information System (INIS)

    A high speed directional solidification technique was used to fabricate lamellar Pb-Cd and (Pb-Mg)--(Cd-Mg) superconductor-normal metal composites in which all the lamellae are oriented perpendicular to the broad surface of the sample. These lamellar composites are found to behave like a large number (approximately 1000) of superconducting-normal-superconducting junctions. For the Pb-Cd eutectic system, the critical current densities and critical fields have shown no dependence upon the lamellar periods between 1.0 and 3.1 microns. The critical current density of the aligned lamellar Pb-Cd structures was enhanced approximately 50% when compared to quenched eutectic alloy and to pure Pb. The superconducting transition temperature, T/sub c/, varies inversely with the square of the thickness of the superconducting material as expected from Ginzburg-Landau theory. Upon annealing, the Pb lamellae change from type II to type I superconductivity

  12. Photoluminescence properties of ZnS nanoparticles co-doped with Pb 2+ and Cu 2+

    Science.gov (United States)

    Yang, Ping; Lü, Mengkai; Xü, Dong; Yuan, Duolong; Zhou, Guangjun

    2001-03-01

    Nanometer-scale ZnS, ZnS:Cu, ZnS:Pb, and ZnS co-doped with Cu 2+ and Pb 2+ have been synthesized using a chemical precipitation method. X-ray diffraction analysis shows that the diameter of the particles is 2-4 nm. These nanocrystals can be doped with copper and lead during the synthesis without altering the X-ray diffraction pattern. However, doping has shifted the luminescence to 530 nm (Cu 2+-doped) and 500-550 nm (co-doped with Cu 2+ and Pb 2+). In the case of ZnS:Pb nanocrystals, a relatively broad emission band (color range from blue to yellow) has been observed and its excitation wavelength shows a red shift. The photoluminescence intensity increases as the ZnS nanoparticles co-doped with Pb 2+ and Cu 2+. The results strongly suggest that doped ZnS nanocrystals, especially two kinds of metals activated ZnS nanocrystals, form a new class of luminescent materials.

  13. Temperature dependence of excitonic transition in ZnSe/ZnCdSe quantum wells

    Institute of Scientific and Technical Information of China (English)

    GUO Zi-zheng; LIANG Xi-xia; BAN Shi-liang

    2005-01-01

    A theoretical calculation for the temperature dependence of the excitonic transition in ZnSe/ZnCdSe quantum wells is performed. The exciton binding energy is calculated with a variational technique by considering the temperature-dependence parameters. Our results show that the exciton binding energy reduces linearly with temperature increasing. We find that the strain due to lattice mismatch and differential thermal expansion decreases with the temperature increasing.

  14. Cd-Pb复合污染在土壤-水稻系统中生态效应的研究%Ecological Effect of Cd-Pb Combined Pollution on Soil-Rice System

    Institute of Scientific and Technical Information of China (English)

    王新; 梁仁禄; 周启星

    2001-01-01

    Pot experiments were conducted to study laws of the migration and accumulation of heavy metals in the soil-rice system and their ecological effect on the system. Results show that in treatment Cd-Pb the crop was 5~7 cm shorter in plant height and 20% less in yield than that in CK. Normal growth of the crops in treatment Cd-Pb and treatment Cd-Pb-Cu-Zn-As was seriously affected.In terms of distribution of heavy metals in grains,the treatments were in the order of treatment Cd-Pb-Cu-Zn-As>treatment Cd-Pb>treatment single element.In treatment Cd-Pb the presence of Pb stimulates the plant to absorb Cd,whereas the presence of Cd inhibits the absorption of Pb by rice.Cd is more mobile than Pb and likely to migrate upwards while Pb tends to accumulate in the root of rice.%采用盆栽试验研究了重金属复合污染物在土壤-水稻系统中迁移、积累规律及生态效应。结果表明:Cd、Pb复合污染使水稻株高比对照的下降了5~7 cm,水稻减产20%,2元素交互作用特别是5元素复合作用影响了水稻的正常生长发育;不同处理中重金属在水稻籽实的分配比例依次为5元素>2元素>单元素;Cd-Pb 2元素交互作用时,Pb元素的存在促进了水稻对Cd元素的吸收,而Cd元素却抑制了水稻对Pb元素的吸收;Cd比Pb元素易向地上部迁移,Pb元素大部分积累于水稻根部。

  15. Highly efficient ZnO porous nanostructure for CdS/CdSe quantum dot sensitized solar cell

    International Nuclear Information System (INIS)

    Porous zinc oxide (ZnO) nanostructure has been prepared by simple one step oxalate route for the fabrication of CdS/CdSe quantum dot sensitized solar cells (QDSSC). The porous ZnO photoanode is sensitized with CdS and CdS/CdSe quantum dots by simple chemical bath deposition technique by controlling the surface agglomeration of quantum dots over ZnO photoanode. The performances of the QDSSCs are examined with both platinum and copper sulfide counter electrodes. The photovoltaic properties of the cells are determined using current–voltage characterization under 1 sun illumination. The transport properties of the QDSSCs have been studied using electrochemical impedance spectroscopy and open circuit voltage decay analysis. The combination of CdS/CdSe/ZnS successive layers over ZnO with CuS counter electrode shows an excellent performance with a maximum power to conversion efficiency of 4.09% under 1 sun illumination. - Highlights: • Porous zinc oxide nanoparticles were prepared by one step oxalate route. • Porous ZnO/CdS/CdSe quantum dots sensitized solar cells were fabricated. • Cell with CuS counter electrodes shows excellent performance than that of Pt counter electrodes. • ZnO/CdS/CdSe/ZnS quantum dots sensitized solar cell recorded 4.09% efficiency

  16. Investigations of Cu, Pb and Zn partitioning by sequential extraction in harbour sediments after electrodialytic remediation

    DEFF Research Database (Denmark)

    Kirkelund, Gunvor Marie; Ottosen, Lisbeth M.; Villumsen, Arne

    2010-01-01

    Electrodialytic remediation was used to remove Cu, Zn and Pb from three different contaminated harbour sediments. Electrodialytic experiments lasting 2 and 4 weeks were performed and 48-86% Cu, 74-90% Zn and 62-88% Pb were removed from the different sediments and the removal increased with longer...... remediation time. A three step sequential extraction scheme (BCR), with an extra residual step, was used to evaluate the heavy metal distribution in the sediments before and after electrodialytic remediation. Cu was mainly associated with the oxidisable phase of the sediment, both before and after remediation....... Zn and Pb were found in the exchangeable and reducible phases before remediation. Zn was still found in the exchangeable and reducible phases after remediation, whereas most Pb was removed from these phases during electrodialytic remediation....

  17. Predictive GIS Model for Potential Mapping of Cu, Pb, Zn Mineralization

    Institute of Scientific and Technical Information of China (English)

    Tarik. B. Benomar; BIAN Fuling

    2006-01-01

    The geologic features indicative of Cu, Pb, Zn mineral deposits in a area are fractures (structure), and host rock sediments. Datasets used include Cu, Pb, Zn deposit points record, geological data, remote sensing imagery (Landsat TM5). The mineral potential of the study area is assessed by means of GIS based geodata integration techniques for generating predictive maps. GIS predictive model for Cu, Pb, Zn potential was carried out in this study area (Weixi) using weight of evidence. The weights of evidence modeling techniques is the data driven method in which the spatial associations of the indicative geologic features with the known mineral occurrences in the area are quantified, and weights statistically assigned to the geologic features. The best predictive map generated by this method defines 24% the area having potential for Cu, Pb, Zn mineralization further exploration work.

  18. Cancer Cell Targeting Using Folic Acid/Anti-HER2 Antibody Conjugated Fluorescent CdSe/CdS/ZnS-MPA and CdTe-MSA Quantum Dots.

    Science.gov (United States)

    Singh, Gurpal; Kumar, Manoj; Soni, Udit; Arora, Vikas; Bansal, Vivek; Gupta, Dikshi; Bhat, Madhusudan; Dinda, Amit K; Sapra, Sameer; Singh, Harpal

    2015-12-01

    CdSe/CdS/ZnS and CdTe quantum dots (QDs) were synthesized by successive ion layer adsorption and reaction (SILAR) technique and direct aqueous synthesis respectively using thiol stabilizers. Synthesized CdSe/CdS/ZnS and CdTe QDs stabilized with 3-mercaptopropionic acid (MPA) and mercaptosuccinic acid (MSA) were used as fluorescent labels after conjugation with folic acid (FA) and anti-HER2 antibodies. Photoluminescence quantum yield of folated CdSe/CdS/ZnS-MPA and CdTe-MSA QDs was 59% and 77% than that of non-folated hydrophilic QDs. The folate receptor-mediated delivery of folic acid-conjugated CdTe-MSA and CdSe/CdS/ZnS-MPA QDs showed higher cellular internalization as observed by confocal laser scanning microscopic studies. Folated and non-folated CdTe-MSA QDs were highly toxic and exhibited only 10% cell viability as compared to > 80% cell viability with CdSe/CdS/ZnS-MPA QDs over the concentration ranging from 3.38 to 50 pmoles. Immunohistochemistry (IHC) results of human breast cancer tissue samples showed positive results with anti-HER2 antibody conjugated CdSe/CdS/ZnS-MPA QDs with better sensitivity and specificity as compared to conventional IHC analysis using diaminobenzedene staining. PMID:26682358

  19. n-(CdMgTe/CdTe)/(p-(CdTe/ZnCdTe/ZnTe)/p-GaAs heterostructure diode for photosensor applications

    Science.gov (United States)

    Yahia, I. S.; AlFaify, S.; Abutalib, M. M.; Chusnutdinow, S.; Wojtowicz, T.; Karczewski, G.; Yakuphanoglu, F.; Al-Bassam, A.; El-Naggar, A. M.; El-Bashir, S. M.

    2016-05-01

    High quality n-(CdMgTe:I/n-CdTe:I)/(p-CdTe:N/p-ZnCdTe:N/p-ZnTe:N)/p-GaAs heterojunction diodes have been fabricated by molecular beam epitaxial growth. The illumination effect on the complex impedance and conductivity of heterostructure diode was investigated. The illumination intensities were taken up to the 200 mW/cm2 with frequency range of 42 Hz to 1 MHz. The observed real and imaginary parts of the complex impedance were strongly dependent on the illumination frequency. The inverse relation was observed between the illumination intensity and the complex impedance. The relaxation mechanism of the diode was analyzed by the Cole-Cole plots. The radius of the Cole-Cole curve decreases with increasing illumination intensity. This suggests a mechanism of illumination dependent on the relaxation process. It is also found that the conductivity increases linearly with increasing the illumination intensity. We can conclude that the new design heterostructure diode in our work is a good candidate in photodetector and optoelectronic applications.

  20. Interaction of Pb and Cd in Soil—Water—Plant System and Its Mechanism: Ⅱ.Pb—Cd Interaction in Rhizosphere

    Institute of Scientific and Technical Information of China (English)

    CHENHUAIMAN; LINQI; 等

    1998-01-01

    The interaction of Pb-Cd can be observed not only in the uptake process of elements by plants and in their influence on the growth,but also in rhizosphere.The changes in extractable Cd and Pb concentrations in the rhizosphere soil of rice plants ,root exudates from wheat and wheat plant and their complexing capacity,with Pa and Cd were investigated under different Pb and Cd treatments.Results showed that the concentration of extractable Cd in the rhizosphere of rice in red soil was markedly increased by Pb-Cd interaction,It increased by 56% in the treatment with Pb and Cd added against that in the treatment with only Cd added in soil . The considerable differences in both composition and amount of root exudate from wheat and rice were found among different treatments.Pb and Cd might be complexed by root exudates ,The concentrations of free Pb and Cd in the solution were increased markedly by adding root exudate from wheat and decreased by that from rice due to Pd-Cd interaction.The distribution patterns of Pb and Cd in roots were affected by Pb-Cd interaction,which accelerated transport of Pb into internal tissue and retarded accumulation of Cd in external tissue.

  1. The plumbide CeZnPb - Structure, magnetism, and chemical bonding

    Science.gov (United States)

    Hermes, Wilfried; Rodewald, Ute Ch.; Chevalier, Bernard; Matar, Samir F.; Eyert, Volker; Pöttgen, Rainer

    2010-05-01

    The plumbide CeZnPb was synthesized from the elements in a sealed tantalum ampoule. Its YPtAs-type structure was refined on the basis of single-crystal X-ray diffraction data: P6 3/ mmc, a = 463.7(2) and c = 1669.6(6) pm, w R2 = 0.1161, 189 F2 values, and 12 variables. CeZnPb crystallizes with a superstructure of AlB 2. The zinc and lead atoms form puckered [Zn 3Pb 3] hexagons, which are stacked in a sequence ABB' A'. The Zn-Pb distances within the layers are 278 pm. The shortest interlayer distance occurs between the zinc atoms of adjacent layers (305 pm). Susceptibility measurements of CeZnPb show Curie-Weiss behavior with an experimental magnetic moment of 2.47(1) μB/mol CeZnPb. CeZnPb shows two antiferromagnetic transitions at TN1 = 3.8 K and TN2 = 2.6 K. Magnetization measurements at 2 K show two metamagnetic transitions at critical fields of approximately 1.1 and 7.0 kOe, underlining the antiparallel spin alignment at zero field. The electronic and magnetic structure is discussed based on scalar relativistic computations using the augmented spherical wave (ASW) method within density functional theory (DFT). As a result, our calculations employing the generalized gradient approximation (GGA) reveal a delicate competition of ferro and antiferromagnetic interactions. Only after properly taking into account the electronic correlations present in CeZnPb via a GGA + U treatment we are able to correctly describe the antiferromagnetic ground state. In addition, our calculations give a clue to the metamagnetic transitions as being due to the inherent geometric frustration of the cerium spin system.

  2. Kinetics of Pb and Zn leaching from zinc plant residue by sodium hydroxide

    OpenAIRE

    Erdem M.; Yurten M.

    2015-01-01

    In the hydrometallurgical zinc production processes, important amount of hazardous solid extraction residue containing unextractable Zn and Pb is generated. Due to increasing demand of metals and the depletion of high grade natural resources, these types of wastes are gaining great importance in the metallurgical industries. In this study, selective leaching and leaching kinetics of Pb and Zn from zinc extraction residue were investigated. For this purpose;...

  3. High performance p-i-n CdTe and CdZnTe detectors

    CERN Document Server

    Khusainov, A K; Ilves, A G; Morozov, V F; Pustovoit, A K; Arlt, R D

    1999-01-01

    A breakthrough in the performance of p-i-n CdTe and CdZnTe detectors is reported. The detector stability has been significantly improved, allowing their use in precise gamma and XRF applications. Detectors with energy resolution close to Si and Ge were produced operating with only -30--35 deg. C cooling (by a Peltier cooler of 15x15x10 mm size and a consumed power less than 5 W). Presently detectors with volume of up to 300 mm sup 3 are available. In terms of photoelectric effect efficiency it corresponds to HPGe detectors with volumes of about 1.5 cm sup 3. The possibilities of further improvement of CdTe and CdZnTe detector characteristics are discussed in this paper.

  4. High performance p-i-n CdTe and CdZnTe detectors

    Science.gov (United States)

    Khusainov, A. Kh; Dudin, A. L.; Ilves, A. G.; Morozov, V. F.; Pustovoit, A. K.; Arlt, R. D.

    1999-06-01

    A breakthrough in the performance of p-i-n CdTe and CdZnTe detectors is reported. The detector stability has been significantly improved, allowing their use in precise gamma and XRF applications. Detectors with energy resolution close to Si and Ge were produced operating with only -30--35°C cooling (by a Peltier cooler of 15×15×10 mm size and a consumed power less than 5 W). Presently detectors with volume of up to 300 mm 3 are available. In terms of photoelectric effect efficiency it corresponds to HPGe detectors with volumes of about 1.5 cm 3. The possibilities of further improvement of CdTe and CdZnTe detector characteristics are discussed in this paper.

  5. Rare Earth Elements and Geochemical Partitioning of Zn and Pb in Sediments of an Urban River

    Directory of Open Access Journals (Sweden)

    Shaila Sharmin

    2010-01-01

    Full Text Available Problem statement: Urban river sediment pollution due to Zn and Pb is a serious problem in all over the world. The source and level of Zn and Pb pollution in sediments of Nomi River of Ota Ward, one of the most industrialized areas in Tokyo, Japan is still lacking. Approach: The present study focused on Rare Earth Elements (REEs and geochemical partitioning of Zn and Pb in sediments of 19 sampling sites of Nomi River in order to examine the mobility pattern. The amounts of Zn and Pb in the liquid extract of 5 (five geochemical phases were measured by using Inductively Coupled Plasma Mass Spectrometry (ICP-MS and the concentrations of REEs in sediments were determined by using X-ray Fluorescence Spectroscopy (XRF. Results: Speciation data indicate dominant labile fraction of Zn, which is related to the presence of several anthropogenic influence of the investigated area. Enrichment Factor (EFc and Index of geoaccumulation (Igeo value were compatible with the result, which confirm pollution status of Zn. Environmental risk of Zn and Pb were also evaluated using the Risk Assessment Code (RAC and sequential extraction results and found Zn poses high to very high risk (34-59, whereas Pb poses low to medium environmental risk (0-19. Conclusion: The mean values of REEs and other minor elements were lower or very close to average shale and Japanese river sediment value but Sr, Sn, Zr and Sb contents were little bit higher than average Japanese river sediment values. Anthropogenic activities, prevalent in the study area play a key role in the accumulation of Zn and Pb in aquatic system. Early warning on the sediment pollution to respective authorities help in preserving the aquatic system from further degradation of the river.

  6. Thermal stability of CdZnO thin films grown by molecular-beam epitaxy

    International Nuclear Information System (INIS)

    CdZnO thin films with near-band-edge (NBE) photoluminescence (PL) emission from 2.39 eV to 2.74 eV were grown by plasma-assisted molecular-beam epitaxy on c-plane sapphire substrates with 800 deg. C in situ annealing. CdZnO thin films evolve from pure wurtzite (wz) structure, to mixture of wz and rock-salt (rs) structures confirmed by X-ray diffraction studies. Rapid-thermo-annealing (RTA) was performed on in situ annealed CdZnO samples. Pure wz CdZnO shows insignificant NBE PL peak shift after RTA, while mixture structure CdZnO shows evident blue shifts due to phase change after annealing, indicating the rs phase CdZnO changes to wz phase CdZnO during RTA process.

  7. (Zn,Cd)S porous layers for dye-sensitized solar cell application

    Energy Technology Data Exchange (ETDEWEB)

    Olea, Alfredo; Sebastian, P.J. [Coordinacion de Solar-H2-Celda de Combustible, CIE-UNAM 62580 Temixco, Morelos (Mexico)

    1998-07-23

    Porous (Zn,Cd)S structures were formed by screen printing of CdS, ZnS, ZnCl{sub 2} and CdCl{sub 2} powders in different configurations and sintering in air at high temperature. The XRD (X-ray diffraction) analysis of these layers sintered at different temperatures revealed that the CdO and ZnO formation in the (Zn,CdS) matrix is by the phase transformation of (Zn,Cd)S. The structure, composition and photosensitivity of this composite structure depends on the sintering temperature, sintering atmosphere and the flux to semiconductor (F/S) ratio. The results indicate that the screen printed (Zn,Cd)S structure may be used as a photoconductor in solid state devices and as a photoelectrode in photo-electro-chemical energy conversion systems

  8. Si, CdTe and CdZnTe radiation detectors for imaging applications

    OpenAIRE

    Schulman, Tom

    2006-01-01

    The structure and operation of CdTe, CdZnTe and Si pixel detectors based on crystalline semiconductors, bump bonding and CMOS technology and developed mainly at Oy Simage Ltd. And Oy Ajat Ltd., Finland for X- and gamma ray imaging are presented. This detector technology evolved from the development of Si strip detectors at the Finnish Research Institute for High Energy Physics (SEFT) which later merged with other physics research units to form the Helsinki Institute of Physics (HIP). General ...

  9. Kinetics of Pb and Zn leaching from zinc plant residue by sodium hydroxide

    Directory of Open Access Journals (Sweden)

    Erdem M.

    2015-01-01

    Full Text Available In the hydrometallurgical zinc production processes, important amount of hazardous solid extraction residue containing unextractable Zn and Pb is generated. Due to increasing demand of metals and the depletion of high grade natural resources, these types of wastes are gaining great importance in the metallurgical industries. In this study, selective leaching and leaching kinetics of Pb and Zn from zinc extraction residue were investigated. For this purpose; the effects of NaOH concentration, contact time, stirring speed and temperature on the Pb and Zn recovery from the residue were studied. The shrinking core model was applied to the results of the experiments. Leaching results showed that 85.55% Pb and 21.3 % Zn could be leached under the optimized conditions. The leaching of Pb and Zn were found to fit well to shrinking core model with ash layer diffusion control. Activation energy values for Pb and Zn leaching were calculated to be 13.645 and 22.59 kJ/mol, respectively.

  10. Ultrafast Carrier Dynamics in CdSe/CdS/ZnS Quantum Dots

    Institute of Scientific and Technical Information of China (English)

    Guan-xin Yao; Zai-xi Fu; Xian-yi Zhang; Xian-feng Zheng; Xue-han Ji; Zhi-feng Cui; Hong Zhang

    2011-01-01

    The intra- and inter-band relaxation dynamics of CdSe/CdS/ZnS core/shell/shell quantum dots are investigated with the aid of time-resolved nonlinear transmission spectra which are obtained using femtosecond pump-probe technique.By selectively exciting the core and shell carrier,the dynamics are studied in detail.Carrier relaxation is found faster in the conduction band of the CdS shell (about 130 fs) than that in the conduction band of the CdSe core (about 400 fs).From the experiments it is distinctly demonstrated the existence of the defect states in the interface between the CdSe core and the CdS shell,indicating that ultrafast spectroscopy might be a suitable tool in studying interface and surface morphology properties in nanosystems.

  11. Contamination of the soil along the river Zletovska by metals as by products of economic production of Pb-Zn

    OpenAIRE

    Boev, Blazo; Lepitkova, Sonja

    1996-01-01

    This paper shows the results constraining the degree of contamination of soil along the course of the River Zletovska by some mewls. These are by- products of economic production of lead-zinc ores which are common in this area. Contamination of soils by some metals, first of all by Pb, Zn, Cu, Cd, As, Fe, Al, Mn, Na, K is an important issue for the quality of the environment in which we live from several aspects: accumulation of waters under river alluvions; agricultural produ...

  12. Translocation analysis and safety assessment in two water spinach cultivars with distinctive shoot Cd and Pb concentrations.

    Science.gov (United States)

    Huang, Baifei; Xin, Junliang; Dai, Hongwen; Liu, Aiqun; Zhou, Wenjing; Liao, Kebing

    2014-10-01

    A pot experiment was conducted to investigate the translocation of cadmium (Cd) and lead (Pb) and assess the safety of edible parts in two cultivars of water spinach (Ipomoea aquatica Forsk.) contrasting in shoot Cd and Pb concentrations. A low-Cd-Pb cultivar (QLQ) and a high-Cd-Pb cultivar (T308) were grown in five soils with different concentrations of Cd and Pb. The results showed that QLQ had lower Cd and Pb concentrations in stems and leaves and higher root Cd concentration than T308 did. Root Pb concentration of T308 dramatically increased with increasing soil Pb concentration and was higher than that of QLQ in the highest Pb treatment. The root-to-stem Cd translocation ability in T308 was 2.3-3.0-fold higher than that in QLQ. Nevertheless, there was no significant difference in root-to-stem Pb translocation between QLQ and T308. The bioconcentration factors (BCFs) for Cd and Pb in the two cultivars remained stable in different Cd or Pb treatments, which were attributable to the homeostatic control mechanisms of Cd and Pb in water spinach. PMID:25028323

  13. Luminescence properties of Pb2+- and Mn2+-activated CdI2 crystals

    International Nuclear Information System (INIS)

    The luminescence properties of CdI2, CdI2:Pb2+, CdI2:Mn2+, and CdI2:(Pb2+,Mn2+) crystals have been studied at temperatures from 85 to 295 K under optical and X-ray excitation. Analysis of new and earlier spectroscopic data suggests that the 560-nm luminescence of CdI2:Pb2+ and CdI2:(Pb2+,Mn2+) crystals under excitation on the long-wavelength component of the A absorption band of Pb2+ centers is due to Pb2+-bound anion excitons. The 640- to 660-nm emission of these crystals is attributable to α centers. The manganese luminescence in the co-doped material originates from both intra-center Mn2+ excitations and a sensitized process due to energy transfer from the host and Pb2+-related centers. The mechanisms of recombination and energy transfer processes in cadmium iodide crystals co-doped with Pb2+ and Mn2+ are discussed

  14. Arabis gemmifera is a hyperaccumulator of Cd and Zn.

    Science.gov (United States)

    Kubota, Hiroshi; Takenaka, Chisato

    2003-01-01

    Hyperaccumulators are essential for phytoremediation of heavy metals. In Europe and North America, many studies have been conducted to find more effective plants for phytoremediation of various pollutants. In Japan, this field of research has just recently come more into focus. A type of fern in Japan, Athyrium yokoscense, is well known as a hyperaccumulator of Cd and Zn. However, it is not suitable for phytoremediation because it is a summer green and grows slowly. Therefore, in order to find hyperaccumulators other than from A. yokoscense, we surveyed plants growing at polluted sites in Japan. We found that the Brassicae Arabis gemmifera is a hyperaccumulator of Cd and Zn, with phytoextraction capacities almost equal to Thlaspi caerulescens. PMID:14750427

  15. PERFORMANCE-LIMITING DEFECTS IN CdZnTe DETECTORS

    International Nuclear Information System (INIS)

    We studied the effects of small, <20 (micro)m, Te inclusions on the energy resolution of CdZnTe gamma-ray detectors using a highly collimated X-ray beam and gamma-rays, and modeled them via a simplified geometrical approach. Previous reports demonstrated that Te inclusions of about a few microns in diameter degraded the charge-transport properties and uniformity of CdZnTe detectors. The goal of this work was to understand the extent to which randomly distributed Te-rich inclusions affect the energy resolution of CZT detectors, and to define new steps to overcome their deleterious effects. We used a phenomenological model, which depends on several adjustable parameters, to reproduce the experimentally measured effects of inclusions on energy resolution. We also were able to hound the materials-related problem and predict the enhancement in performance expected by reducing the size and number of Te inclusions within the crystals

  16. Point Defect Characterization in CdZnTe

    Energy Technology Data Exchange (ETDEWEB)

    Gul,R.; Li, Z.; Bolotnikov, A.; Keeter, K.; Rodriguez, R.; James, R.

    2009-03-24

    Measurements of the defect levels and performance testing of CdZnTe detectors were performed by means of Current Deep Level Transient Spectroscopy (I-DLTS), Transient Charge Technique (TCT), Current versus Voltage measurements (I-V), and gamma-ray spectroscopy. CdZnTe crystals were acquired from different commercial vendors and characterized for their point defects. I-DLTS studies included measurements of defect parameters such as energy levels in the band gap, carrier capture cross sections, and defect densities. The induced current due to laser-generated carriers was measured using TCT. The data were used to determine the transport properties of the detectors under study. A good correlation was found between the point defects in the detectors and their performance.

  17. RNAA determination of As, Cd and Zn in biological materials

    International Nuclear Information System (INIS)

    In connection with the IAEA project 3739/RB the elements Hg, As, Cd and Zn in human spleen, kidney, heart, liver, SRM Bovine Liver 1577a and Bowen's Kale. The consecutive extraction have been chosen as the most rational approach determining these elements in a single specimen. Aiming at getting reliable results well established systems were used (ditizone to separate Hg, Cu and DEDTC to extract As, Cd and Zn). Special attention was paid to the accuracy of the determination. Monitoring, optimization and cooling time and control of chemical yield were carried out in each case. The samples were irradiated in the vertical channel of the IRT-2000 reactor in Sofia, in thermal neutron flux of about 5.1012n.cm-2.s-1 for 24 h. Iron monitor was used and cooling time varied from 20 h to 30 h

  18. Synthesis of CdSe/ZnSe/ZnS Core/Shell Structure Quantum Dots by Hydrothermal Method%水热法合成CdSe/ZnSe/ZnS核壳结构量子点

    Institute of Scientific and Technical Information of China (English)

    胥燕; 王新; 翟镇德; 刘敏; 苏秀荣

    2014-01-01

    本研究采用水热法合成了3-巯基丙酸稳定的具有高荧光活性的CdSe/ZnSe/ZnS核/壳结构量子点,并通过透射电镜对量子点的形貌进行了表征。研究了影响量子点荧光强度的因素,并分析了量子点的稳定性。结果表明,水热法合成的CdSe/ZnSe/ZnS量子点,分布均匀,粒径大小均匀,约为5~8 nm。当激发波长为372 nm时CdSe/ZnSe/ZnS量子点可发射蓝紫色(446 nm)荧光,荧光活性高、荧光稳定性好,毒性低,可用于生物荧光标记、组分测定等。%In the study, 3-mercaptopropionic acid modified CdSe/ZnSe/ZnS core/shell structure quantum dots (QDs) with high fluorescence were prepared by hydrothermal method and characterized via transmission electron microscopy (TEM). The influence factors of the fluorescence intensity and the stability of QDs have been studied. Results showed that excellent CdSe/ZnSe/ZnS QDs with uniform diameter (5-8 nm) were obtained. The prepared CdSe/ZnSe/ZnS QDs emit blue-violet light (446 nm) when excited at 372 nm with low toxicity, high fluorescence intensity and excellent stability, endowing the synthesized CdSe/ZnSe/ZnS QDs applied in biochemical analysis.

  19. ZnTe/CdTe thin-film heterojunctions

    Directory of Open Access Journals (Sweden)

    M.M. Kolesnyk

    2009-01-01

    Full Text Available In this work we have studied the structural and electrophysical properties of the ZnTe/CdTe heterojunctions, obtained by the method of thermal evaporation in quasi-closed volume. Investigations allowed to define the films structural parameters, such as texture, lattice constant, sizes of grains and coherent-scattering domains, micro-deformation level, and their dependence on the conditions of films production as well. Electrophysical investigations allowed to define the charge-transport mechanism in heterojunction.

  20. Recent Progress in CdTe and CdZnTe Detectors

    OpenAIRE

    Takahashi, Tadayui; Watanabe, Shin

    2001-01-01

    Cadmium telluride (CdTe) and cadmium zinc telluride (CdZnTe) have been regarded as promising semiconductor materials for hard X-ray and Gamma-ray detection. The high atomic number of the materials (Z_{Cd} =48, Z_{Te} =52) gives a high quantum efficiency in comparison with Si. The large band-gap energy (Eg ~ 1.5 eV) allows us to operate the detector at room temperature. However, a considerable amount of charge loss in these detectors produces a reduced energy resolution. This problem arises du...

  1. Photoluminescence Spectroscopy of CdZnTe/CdTe Single Strained Quantum Wells

    Science.gov (United States)

    Reno, J. L.; Jones, E. D.

    1991-12-01

    We have grown strained Cd1-xZnxTe/CdTe single strained quantum wells by molecular beam epitaxy. The Zn concentration was varied from 10 to 60% and the well widths were systematically increased until the critical thickness was exceeded. Low-temperature (liquid helium) photoluminescence spectroscopy was used to characterize the films. The energy of the quantum well luminescence is consistent with a simple square well model when strain is included. The critical layer thickness for the CdTe quantum wells was found to be in agreement with the model of Matthews and Blakeslee.

  2. Removal of Cd from Actual Soils Polluted with Cd and Zn and Cd-added Soils by Brassica juncea and Zea mays

    OpenAIRE

    Inoue, Hiromichi; Saeki, Kazutoshi

    2004-01-01

    We have alternated the 3-week cultivation of corn (Zea mays L.) and that of Indian mustard (Brassica juncea (L.) Czern) in a pot with the sequential rotation, corn-Indian mustard-corn-Indian mustard, in order to remove Cd from two actual soils polluted with Cd and Zn, one (low Cd) polluted (LP) containing 6.5mg Cd kg[-1] and 715mg Zn kg[-1] and another (high Cd polluted (HP)) with 13.6mg Cd kg[-1] and 836mg Zn kg[-1]. Fertilizer applications to soil in a rotational cropping can nihibit the ...

  3. Photosensitive EPR spectra of Pb-doped ZnS single crystals

    International Nuclear Information System (INIS)

    Photosensitive EPR investigations of lead-doped ZnS single crystals have been made. The results of excitation and quenching measurements are discussed in terms of the A-centre model, assuming a Zn vacancy associated with a neutral Pb2+ impurity on next cation site. A simple level model, involving the energetic positions of the photosensitive impurities in the band gap of ZnS, is proposed to explain the EPR excitation and quenching spectra. (author)

  4. Infrared Illuminated CdZnTe detectors with improved performance

    International Nuclear Information System (INIS)

    It was found that IR illumination of a properly chosen wavelength and intensity can significantly improve spectrometric characteristics of CdZnTe quasi-hemispherical detectors [1]. Improving of the spectrometric characteristics is due to improvement of uniformity of charge collection by the detector volume. For operation at room temperature the optimal wavelength of IR illumination is about 940 nm, but for operation at lower temperature of -20 deg. C the optimal wavelengths of IR illumination is about 1050 nm. Infrared illumination can be performed using conventional low-power IR LEDs. Application of SMD LEDs allows produce miniature detection probes with IR illuminated CdZnTe detectors. We have fabricated and tested a variety of detection probes with CdZnTe quasi-hemispherical detectors from the smallest with volumes of 1-5 mm3 to larger with volumes of 1.5 cm3 and 4.0 cm3. The use of IR illumination significantly improves spectrometric characteristics of the probes operating at room temperature, especially probes with detectors of large volumes. The probe with the detector of 4 cm3 without IR illumination had energy resolution of 24.2 keV at 662 keV and of 12.5 keV with IR illumination. (authors)

  5. Alpha particle response characterization of CdZnTe

    Energy Technology Data Exchange (ETDEWEB)

    Amman, Mark; Lee, Julie S.; Luke, Paul N.

    2001-06-28

    The coplanar-grid as well as other electron-only detection techniques are effective in overcoming some of the material problems of CdZnTe and, consequently, have led to efficient gamma-ray detectors with good energy resolution while operating at room temperature. The performance of these detectors is limited by the degree of uniformity in both electron generation and transport. Despite recent progress in the growth of CdZnTe material, small variations in these properties remain a barrier to the widespread success of such detectors. Alpha-particle response characterization of CdZnTe crystals fabricated into simple planar detectors is an effective tool to accurately study electron generation and transport. We have used a finely collimated alpha source to produce two-dimensional maps of detector response. A clear correlation has been observed between the distribution of precipitates near the entrance contact on some crystals and their alpha-response maps. Further studies are ongoing to determine the mechanism for the observed response variations and the reason for the correlation. This paper presents the results of these studies and their relationship to coplanar-grid gamma-ray detector performance.

  6. Alpha particle response characterization of CdZnTe

    International Nuclear Information System (INIS)

    The coplanar-grid as well as other electron-only detection techniques are effective in overcoming some of the material problems of CdZnTe and, consequently, have led to efficient gamma-ray detectors with good energy resolution while operating at room temperature. The performance of these detectors is limited by the degree of uniformity in both electron generation and transport. Despite recent progress in the growth of CdZnTe material, small variations in these properties remain a barrier to the widespread success of such detectors. Alpha-particle response characterization of CdZnTe crystals fabricated into simple planar detectors is an effective tool to accurately study electron generation and transport. We have used a finely collimated alpha source to produce two-dimensional maps of detector response. A clear correlation has been observed between the distribution of precipitates near the entrance contact on some crystals and their alpha-response maps. Further studies are ongoing to determine the mechanism for the observed response variations and the reason for the correlation. This paper presents the results of these studies and their relationship to coplanar-grid gamma-ray detector performance

  7. Uptake and fate of Cd and Zn in edible fungi of the Agaricus bisporus species

    Energy Technology Data Exchange (ETDEWEB)

    Huetter, M.

    1979-01-01

    Cd and Zn were added to growth substrate of fungi in order to investigate the Cd uptake and the effects of Zn on Cd uptake in the edible fungus Agaricus bisporus. Fungus yields were found to decrease with Cd uptake. This effect was completely overcome and sometimes even overcompensated by adding zinc. Cd concentrations in the fungi increased with the soil Cd concentration: When Cd (5.0 and 10.0 mg/kg Fg) was added to the soil cover as well as to the substrate, Cd concentrations in the fungi were found to be about 70% higher than in fungi where the same amount of Cd had been added only to the substrate. The following interactions between Cd and Zn uptake were observed: Low soil Cd concentrations enhance Zn uptake. In contrast, Zn enhances Cd uptake in fungi with low Cd concentrations. At high soil Cd concentrations, Zn inhibits Cd uptake. Cd concentrations in the fungi increased with the age of the cultures and with the size of the fungi. The highest concentrations were found in the lamellae. The enrichment factors are lower in the cultivated variety (0.6 to 1.4 in dependence of the soil Cd concentration) than in wild-growing fungi.

  8. Growth of CdZnTe Crystals the Bridgman Technique with Controlled Overpressures of Cd

    Science.gov (United States)

    Su, Ching-Hu; Lehoczky, S. L.

    2008-01-01

    Cd(1-x)Zn(x)Te crystals with x = 0.15 and 0.20, were grown in this study by closed-ampoule directional solidification (Bridgman) technique with a controlled Cd overpressure. The growth ampoule was made of quartz with inner diameter from 20 to 40 mm and a tapered length of 2.5 cm at the growth tip. Both unseeded and seeded growths were performed with total material charges up to 400 g. After the loading of starting CdZnTe material, a typical amount of 2 g of Cd was also loaded inside a Cd reservoir basket, which was attached beneath the seal-off cup. The ampoule was sealed off under a vacuum below lxl0(exp -5) Torr. The sealed ampoule was placed inside a 4-zone Bridgman furnace - a Cd reservoir zone with a heat-pipe furnace liner on the top, followed by a hot zone, a booster heating zone and a cold zone at the bottom. The Cd zone was typically 300 to 400 C below the hot zone setting. High resistivity material has been obtained without any intentional dopants but has been reproducibly obtained with In doping. The crystalline and the electrical properties of the crystals will be reported.

  9. Thermal analysis and prediction of phase equilibria in ternary Pb-Zn-Ag system

    Directory of Open Access Journals (Sweden)

    Živković D.

    2011-01-01

    Full Text Available Ternary Pb-Zn-Ag system is typical for some physicochemical processes going on in refining phase in the extractive metallurgy of lead. Therefore, investigation of mentioned system is important from both theoretical and practical research of the phenomena occurring during the lead desilverizing process. The results of experimental investigation using differential thermal analysis (DTA and thermodynamic calculation of phase equilibria in Pb-Zn-Ag system according to CALPHAD method, in the sections with Zn:Ag mass ratio equal to 90:10, 70:30 and 50:50, are presented in this paper.

  10. Optical and Structural Properties of Zn-Cd-Mn-Se Double Quantum Well Systems

    Science.gov (United States)

    Matsumoto, Takashi; Ohmori, Kenta; Kodama, Kazuki; Hishikawa, Masao; Fukasawa, Sakyo; Iwasaki, Fumiaki; Muranaka, Tsutomu; Nabetani, Yoichi

    2011-05-01

    Double quantum well (DQW) structures consisting of a ZnCdSe well and a ZnCdMnSe well separated by a ZnSe barrier are grown with molecular beam epitaxy (MBE). The DQW structures are characterized by using X-ray diffraction measurement and simulation. Thickness of each well layer is designed so that the lowest energy level of ZnCdMnSe well is close to the excited level of the ZnCdSe well. Optical properties of the DQWs are studied with photoluminescence (PL) and reflection spectra in external magnetic fields up to 8 T in the Faraday geometry. Exciton transfer from ZnCdMnSe well to ZnCdSe well is observed in magneto PL with energy selective photoexcitation. Exciton energies in ground and excited states are estimated from PL excitation spectra and reflection spectra.

  11. THE EFFECT OF pH ON BIOACCUMULATION OF Cd, Hg AND Pb BY WATER HYACINTH

    OpenAIRE

    Syahrul, Muh.

    2014-01-01

    Water hyacinth grows and multiplies rapidly in the water contaminated by heavy metals such as Cd, Hg, and Pb.. The water hyacinth was planted in Long Ashton media at varying pH, concentrations of Cd, Hg, and Pb and planting time. The roots adsorbed more Cd, Hg and Pb than the stalks and leaves. The maximum absorption was found at pH 5.0 and the minimum at pH 7.0. The higher the metal concentration in the media and longer the planting time, the absorption of the metal ion increased co...

  12. Divalent Cu, Cd, and Pb Biosorption in Mixed Solvents

    Directory of Open Access Journals (Sweden)

    M. H. Al-Qunaibit

    2009-01-01

    Full Text Available Dead dried Chlorella vulgaris was studied in terms of its performance in binding divalent copper, cadmium, and lead ions from their aqueous or 50% v/v methanol, ethanol, and acetone solutions. The percentage uptake of cadmium ions exhibited a general decrease with decrease in dielectric constant values, while that of copper and lead ions showed a general decrease with increase in donor numbers. Uptake percentage becomes less sensitive to solvent properties the larger the atomic radius of the biosorbed ion, and uptake of copper was the most affected. FT-IR analyses revealed stability of the biomass in mixed solvents and a shift in vibrations of amide(I and (II, carboxylate, glucose ring, and metal oxygen upon metal binding in all media. ΔνCOO values (59–69 cm−1 confirmed bidentate metal coordination to carboxylate ligands. The value of νasCOO increased slightly upon Cu, Cd, and Pb biosorption from aqueous solutions indicating lowering of symmetry, while a general decrease was noticed in mixed solvents pointing to the opposite. M–O stretching frequencies increased unexpectedly with increase in atomic mass as a result of solvent effect on the nature of binding sites. Lowering polarity of the solvent permits variations in metal-alga bonds strengths; the smaller the metal ion, the more affected.

  13. Cyclotron resonance excitation spectroscopy of CdTe and of CdTe/CdZnTe quantum wells

    Science.gov (United States)

    Lavigne, B.; Cox, R. T.

    1990-04-01

    Photoconductivity spectra for II-VI semiconductor samples were obtained without any need for electrical contacts by measuring the wavelength dependence of free-carrier cyclotron resonance at 35 GHz. For bulk CdTe, the surprisingly efficient creation of free electrons for h v below the bandgap energy is attributed to exciton-impurity interactions. Auger recombination and inelastic polariton-donor scattering are considered. Preliminary results for CdTe.CdZnTe quantum wells show sharp peaks corresponding to quantized states of free excitons in the well.

  14. Superplastic forming of the Cd-17.4Zn alloy; Conformado superplastico de la aleacion Cd-17.4Zn

    Energy Technology Data Exchange (ETDEWEB)

    Llanes-Briceno, J. A.; Torres-Villasenor, G. [Universidad Nacional Autonoma de Mexico, Mexico, D.F. (Mexico)

    2000-06-01

    In the present work the necessary steps to carry on the superplastic forming of the Cd-17.4Zn alloy are defined. The use of either atmospheric pressure or gas pressure as forming tools is analyzed. The optimum values of the variable involved (temperature, maximum strain and sensitivity index) are determined while a method for the characterization of futures superplastic alloys is set forth. The experimental characterization of the superplastic forming is achieved with free bulging of circular membranes of 12, 16, 24, 32 and 40 mm in diameter and with three different membrane thicknesses (0.4, 0.6, 0.8 mm). [Spanish] Se definen los pasos necesarios para el conformado superplastico de la aleacion Cd-17.4 Zn. Se comparan la presion atmosferica y el gas a presion como herramientas de conformado. Se determinan los valores optimos de la variables involucradas (temperatura, deformacion maxima e indice de sensibilidad) y se plantea una metodologia para la caracterizacion de futuras aleaciones superplasticas. El conformado superplastico se caracteriza experimentalmente mediante el inflado libre de membranas circulares de 12, 16, 24, 32 y 40 mm de diametro y tres diferentes espesores (0.4, 0.6 y 0.8 mm). Se muestra la estructura perlitica (enfuiada al aive Cd-17.4Zn) y la estructura grano fino. Se muestra la profundidad de deformacion en tres espesores (0.4, 0.6, 0.8 mm) a P=200 Kpa y T = 200 y a T = 230.

  15. Excitons, biexcitons, and phonons in ultrathin CdSe/ZnSe quantum structures

    DEFF Research Database (Denmark)

    Gindele, F.; Woggon, Ulrike; Langbein, Wolfgang Werner; Hvam, Jørn Märcher; Leonhardi, K.; Hommel, D.; Selke, H.

    1999-01-01

    nanostructures consist of a coherently strained Zn1-xCdxSe/ZnSe quantum well with embedded islands of higher Cd content with sizes of a few nanometer due to strain-induced CdSe accumulation. The local increase in CdSe concentration results in a strong localization of the excitonic wave function, in an increase...

  16. Variation of grain Cd and Zn concentrations of 110 hybrid rice cultivars grown in a low-Cd paddy soil

    Institute of Scientific and Technical Information of China (English)

    SHI Jing; LI Lianqing; PAN Genxing

    2009-01-01

    Enhanced Cd uptake and Zn depletion in rice grains and high potential for food Cd exposure by the high-yielding hybrid cultivars had been addressed.A field experiment was conducted in 2006 to determine the difference in grain Cd and Zn between cultivars.Total 110 cultivars including super rice and common hybrid rice cultivars were grown on a single paddy soil (Entic Haplaquept) with a neutral reaction and low total Cd content.Grain Cd and Zn concentrations were determined with graphite atomic adsorption spectrophotometer (GFAAS) and flame atomic adsorption spectrophotometer (AAS) respectively.Wide variation of Cd content in grain was determined in a range of 0.004-0.057 mg/kg, while the Zn content in a range of 10.25-30.06 mg/kg among the cultivars.Higher Cd but lower Zn concentration in grains of super rice cultivars was observed compared to the common hybrid ones.A highly significant positive linear correlation of grain Cd/Zn with grain Cd was found for super rice and common hybrid cultivars, meanwhile much higher slope for these hybrid cultivars than the reported non-hybrid cultivars was also observed.Using the limit value of the Chinese chemical guidelines for foods (MOHC and SSC, 2005), calculated potential risk of food Cd exposure with 'Zn hungry' through subsistence diet intake was prominent with all the studied 110 hybrid rice cultivars, possessing high potential health problems for rice production in South China using the super rice cultivars.Breeding of genotypes of rice cultivars with low grain Cd and low Cd/Zn ratio is needed for rice production in acidic red soils where Cd bioavailability is prevalently high in South China.

  17. EMPIRICAL MODELS OF PB AND CD PARTITIONING USING DATA FROM 13 SOILS, SEDIMENTS AND AQUIFER MATERIALS

    Science.gov (United States)

    Lead (Pb) and cadmium (Cd) are two of the most common toxicants found in contaminated environments. Because solubilization of these metallic elements from the solid phase can influence their fate, transport and bioavailability, the partitioning coefficient (Kd) for these metals ...

  18. Speciation and behaviour of Cd, Pb and Cu in Zuari Estuary, west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    George, M.D.

    Dissolved labile and nonlabile forms of Cd, Pb and Cu in Zuari Estuary, Goa, India measured for a period of 14 months showed lowest concentrations during the SW monsoon (June-September) while maximum concentrations were observed during...

  19. High-level Zn and Cd tolerance in Silene paradoxa L. from a moderately Cd- and Zn-contaminated copper mine tailing

    International Nuclear Information System (INIS)

    Cadmium and zinc tolerance were examined in populations of Silene paradoxa, one from uncontaminated calcareous soil (CVD) and one from a mine tailing (FC) (Cd < 1-15 ppm, Zn 400-1300 ppm, pH 2-6). The mine population exhibited extremely high Zn and Cd tolerance levels, although the degrees of Cd and Zn enrichment relatively low at the population site. Cd and Zn hypertolerance in FC were associated with reduced rates of accumulation of these metals, both in roots and shoots (Cd), or exclusively in shoots (Zn). However, exclusion potentially explained only a minor part of the superior tolerance in FC. Cd hypertolerance in FC was associated with decreased, rather than enhanced phytochelatin accumulation. The remarkably high levels of Cd and Zn hypertolerance in FC might relate to the low soil pH, due to oxidation of sulphide minerals, and the absence of soil organic matter at the FC site. - Silene paradoxa from a copper mine exhibits extreme levels of Zn and Cd tolerance

  20. Temperature dependence of the cyclotron mass in ZnCdSe/ZnSe multi-QWs

    International Nuclear Information System (INIS)

    The temperature dependence of the cyclotron resonance mass (CRM) of the magnetopolaron in ZnCdSe/ZnSe multi-quantum wells with strong magnetic field is investigated theoretically using the Lee-Low-Pines variational method. Contributions to the CRM, due to the nonparabolicity of the conduction band and the coupling of electron with both confined longitudinal optical and interface optical phonons, are considered. Results of our calculations are compared with the experimental data, and a qualitative agreement is found over a large temperature range. We show that these three contributions complement each other to determine the cyclotron mass as a function of the temperature. (author)

  1. Controlled building of CdSe@ZnS/Au and CdSe@ZnS/ Au2S/Au nanohybrids

    Institute of Scientific and Technical Information of China (English)

    Raquel E. Galian[1; Pilar Diaz[1; Antonio Ribera[1; Alejandro Rincon-Bertolin[1; Said Agouram[2; Julia Perez-Prieto[1

    2015-01-01

    The addition of Au3. to spherical amine-capped CdSe@ZnS nanoparticles in toluene at room temperature and under darkness can lead to ternary CdSe@ZnS/Au nanohybrids. We demonstrate that this happens only when the nanoparticles possess a relatively thin ZnS shell, thus showing that thickness plays a key role in gold deposition on the CdSe@ZnS nanoparticle surface. Our hypothesis is that the amine ligand acts as the reductant of Au3+ ions into Au+ ions, whose affinity for sulfur would keep them at the CdSe@ZnS surface. This interaction stabilizes the Au+ ion, making it less prone to reduction than a non-coordinated Au+ ion. In CdSe@ZnS with a thin shell, Au+ ions at the surface of, or most probably within, the ZnS shell cause the transfer of Cd2+ ions into the solution. Subsequently, the core Se2- anion, which is a better reductant than the shell S2- reduces Au+ ions to Au(0), and large gold nanoparticles (AuNPs) are quickly deposited on the CdSe@ZnS surface in room temperature process, leading to ternary CdSe@ZnS/Au nanohybrids. In solution, these ternary nanohybrids progressively transform into quaternary CdSe@ZnS/Au2S/Au nanohybrids due to the reaction of the shell S2- anion with the remaining Au+ at the CdSe@ZnS surface, thus leading to the growth of Au2S nanoparticles on the CdSe@ZnS surface while Zn concomitantly leaches from the nanohybrid into the solution. Photoirradiation of the heterostructures with visible light enhances their emission efficiency. Comparatively, irradiation of the precursors, i.e., CdSe@ZnS nanoparticles, causes a drastic decrease in their emission accompanied by a blue shift of their emission maximum. The optical properties of these nanohybrids were analyzed by absorption and fluorescence (steady-state and time-resolved) spectroscopy, and the composition of the samples and the chemical states were determined by energy dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy

  2. Quantifying Pb and Cd complexation by alginates and the role of metal binding on macromolecular aggregation

    OpenAIRE

    Lamelas, Cristina; Avaltroni, F; Benedetti, Marc,; Wilkinson, Kevin J; Slaveykova, Vera

    2005-01-01

    The Pb and Cd binding capacity of alginates were quantified by the determination of their complex stability constants and the concentration of complexing sites using H+, Pb2+, or Cd2+ selective electrodes in both static and dynamic titrations. Centrifugation filter devices (30 kDa filter cutoff), followed by inductively coupled plasma mass spectrometry (ICP-MS) measurements of lead or cadmium in the filtrates, were used to validate the results. The influence of ionic strength, pH, and the met...

  3. A facile route to aqueous Ag:ZnCdS and Ag:ZnCdSeS quantum dots: Pure emission color tunable over entire visible spectrum

    International Nuclear Information System (INIS)

    Highlights: • For the first time, a highly reactive and aqueous sulfur precursor was obtained. • The obtained Ag-doped QDs exhibited high PL QY as high as 40%. • The emission color was tunable and could span entire visible spectrum. • We provided a versatile approach to other aqueous multinary chalcogenide QDs. - Abstract: Aqueous Ag:ZnCdS quantum dots (QDs) with pure, color-tunable fluorescence were prepared based on co-nucleation doping strategy by using a highly reactive S powder precursor, which was reduced by NaBH4 at high temperature of 180 °C in a closed hydrothermal autoclave. For a meaningful comparison, thiourea as a relatively low reactive precursor was employed to test the advantages of this highly reactive S powder precursor in synthetic chemistry. The influences of various experimental variables, including the Zn/Cd ratio and Ag-doping concentration, on the optical properties of Ag:ZnCdS QDs were systematically investigated. The color-tunable quarternary Ag:ZnCdSeS QDs were also successfully prepared via the variation of Se/S precursor ratio based on the similar reactivity of the Se and S powder precursors. Further, the highly efficient Ag:ZnCdS/ZnS and Ag:ZnCdSeS/ZnS core/shell QDs were constructed by the deposition of the ZnS shell around the crude Ag:ZnCdS and Ag:ZnCdSeS core QDs. The results indicated that this facile synthetic route would provide a versatile approach for preparation of other aqueous multinary metal chalcogenide QDs

  4. Redistribution of Pb, Zn and Cu Fractions in Tailing Soils Treated with Different Extractants

    Institute of Scientific and Technical Information of China (English)

    LIU Yun-Guo; WANG Xian-Hai; ZENG Guang-Ming; LI Xin; ZHOU Chun-Hua; FAN Ting; LI Yong-Li; YUAN Xin-Zhong

    2006-01-01

    The efficiency of EDTA, HNO3 and CaCl2 as extractants to remove Pb, Zn and Cufrom tailing soils without varying soil pH was investigated with distributions of Pb, Zn and Cu being determined before and after extraction using the sequential extraction procedure of the optimized European Community Bureau of Reference (BCR). Results indicated that EDTA and HNO3 were both effective extracting agents. The extractability of extractants for Pb and Zn was in the order EDTA > HNO3 > CaCl2, while for Cu it was HNO3 > EDTA > CaCl2. After EDTA extraction, the proportion of Pb, Zn and Cu in the four fractions varied greatly, which was related to the strong extraction and complexation ability. Before and after extraction with HNO3 and CaCl2, the percentages of Pb, Zn and Cu in the reducible, oxidizable and residual fractions changed little compared to the acid-extractable fraction. The lability of metal in the soil andthe kinds of extractants were the factors controlling the effects of metal extraction.

  5. Immobilization of Zn, Cu, and Pb in contaminated soils using phosphate rock and phosphoric acid

    International Nuclear Information System (INIS)

    Considerable research has been done on P-induced Pb immobilization in Pb-contaminated soils. However, application of P to soils contaminated with multiple heavy metals is limited. The present study examined effectiveness of phosphoric acid (PA) and/or phosphate rock (PR) in immobilizing Pb, Cu, and Zn in two contaminated soils. The effectiveness was evaluated using water extraction, plant uptake, and a simple bioaccessibility extraction test (SBET) mimicking metal uptake in the acidic environment of human stomach. The possible mechanisms for metal immobilization were elucidated using X-ray diffraction, scanning electron microscopy, and chemical speciation program Visual MINTEQ. Compared to the control, all P amendments significantly reduced Pb water solubility, phytoavailability, and bioaccessibility by 72-100%, 15-86%, and 28-92%, respectively. The Pb immobilization was probably attributed to the formation of insoluble Pb phosphate minerals. Phosphorus significantly reduced Cu and Zn water solubility by 31-80% and 40-69%, respectively, presumably due to their sorption on minerals (e.g., calcite and phosphate phases) following CaO addition. However, P had little effect on the Cu and Zn phytoavailability; while the acid extractability of Cu and Zn induced by SBET (pH 2) were even elevated by up to 48% and 40%, respectively, in the H3PO4 treatments (PA and PR + PA). Our results indicate that phosphate was effective in reducing Pb availability in terms of water solubility, bioaccessibility, and phytoavailability. Caution should be exercised when H3PO4 was amended to the soil co-contaminated with Cu and Zn since the acidic condition of SBET increased Cu and Zn bioaccessibility though their water solubility was reduced.

  6. Adsorption behavior of Pb2+ and Cd2+ ions on bauxite flotation tailings

    Institute of Scientific and Technical Information of China (English)

    WANG Yu-hua; LAN Ye; HUANG Chuan-bing

    2008-01-01

    The adsorption behavior of Pb2+ and Cd2+ ions on bauxite flotation railings was investigated to demonstrate the adsorptivity of the bauxite flotation tailings. The adsorption percentage of Pb2+ and Cd2+ ions as a function of adsorbent dosage, solution pH value and shaking time were determined by batch experiments. The maximum adsorption percentage of 99.93% for Pb2+ ions and 99.75% for Cd2+ ions were obtained by using bauxite flotation railings as adsorbent. The methods, such as zeta potentials, specific surface area measurements and the analysis of adsorption kinetics, were introduced to analyze the adsorption mechanisms of the Pb2+ ions on bauxite flotation tailings. The isoelectric point of bauxite flotation railings shifts from 3.6 to 5.6 in the presence of Pb2+ ions. The specific surface area of bauxite flotation tailings changes from 12.57 to 20.63 m2/g after the adsorption of Pb2+ ions. These results indicate that a specific adsorption of the cation species happens on the surface of bauxite flotation tailings. Adsorption data of Pb2+ ions on the surface of bauxite flotation tailings can be well described by Langmuir model, and the pseudo-second-order kinetic model provides the best correlation for the adsorption data of Pb2+ and Cd2+ ions on bauxite flotation railings.

  7. Leakage current measurements on pixelated CdZnTe detectors

    International Nuclear Information System (INIS)

    In the field of the R and D of a new generation hard X-ray cameras for space applications we focus on the use of pixelated CdTe or CdZnTe semiconductor detectors. They are covered with 64 (0.9x0.9 mm2) or 256 (0.5x0.5 mm2) pixels, surrounded by a guard ring and operate in the energy ranging from several keV to 1 MeV, at temperatures between -20 and +20 oC. A critical parameter in the characterisation of these detectors is the leakage current per pixel under polarisation (∼50-500 V/mm). In operation mode each pixel will be read-out by an integrated spectroscopy channel of the multi-channel IDeF-X ASIC currently developed in our lab. The design and functionality of the ASIC depends directly on the direction and value of the current. A dedicated and highly insulating electronics circuit is designed to automatically measure the current in each individual pixel, which is in the order of tens of pico-amperes. Leakage current maps of different CdZnTe detectors of 2 and 6 mm thick and at various temperatures are presented and discussed. Defect density diagnostics have been performed by calculation of the activation energy of the material

  8. Chemical bath deposition of CdS thin films doped with Zn and Cu

    Indian Academy of Sciences (India)

    A I Oliva; J E Corona; R Patiño; A I Oliva-Avilés

    2014-04-01

    Zn- and Cu-doped CdS thin films were deposited onto glass substrates by the chemical bath technique. ZnCl2 and CuCl2 were incorporated as dopant agents into the conventional CdS chemical bath in order to promote the CdS doping process. The effect of the deposition time and the doping concentration on the physical properties of CdS films were investigated. The morphology, thickness, bandgap energy, crystalline structure and elemental composition of Zn- and Cu-doped CdS films were investigated and compared to the undoped CdS films properties. Both Zn- and Cu-doped CdS films presented a cubic crystalline structure with (1 1 1) as the preferential orientation. Lower values of the bandgap energy were observed for the doped CdS films as compared to those of the undoped CdS films. Zn-doped CdS films presented higher thickness and roughness values than those of Cu-doped CdS films. From the photoluminescence results, it is suggested that the inclusion of Zn and Cu into CdS crystalline structure promotes the formation of acceptor levels above the CdS valence band, resulting in lower bandgap energy values for the doped CdS films.

  9. Highly fluorescence-stable blue CdZnS/ZnS quantum dots against degradable environmental conditions

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Ki-Heon; Lee, Jeong-Hoon; Kang, Hee-Don; Han, Chang-Yeol [Department of Materials Science and Engineering, Hongik University, Seoul 121-791 (Korea, Republic of); Bae, Seung Muk [Kunsan National University Center For Research Facilities, Kunsan National University, Gunsan, Jeonbuk 573-701 (Korea, Republic of); Lee, Yangjin; Hwang, Jun Yeon [Institute of Advanced Composite Materials, Korea Institute of Science and Technology, Jeonbuk 565-905 (Korea, Republic of); Yang, Heesun, E-mail: hyang@hongik.ac.kr [Department of Materials Science and Engineering, Hongik University, Seoul 121-791 (Korea, Republic of)

    2014-10-15

    Graphical abstract: Blue-emitting CdZnS/ZnS alloy QDs exhibited the excellent fluorescent stability against a thorough purification cycle, long-term UV illumination, and hydrophobic-to-hydrophilic ligand exchange. - Highlights: • Highly efficient, color-pure blue CdZnS/ZnS QDs are synthesized. • Fluorescent properties of the QDs remain unchanged against various degradable conditions. • Closely-packed solid QD film is compared with QD solution in PL QY and emission decay dynamics. - Abstract: We report on synthesis of highly efficient, color-pure blue CdZnS/ZnS quantum dots (QDs) and their excellent fluorescent stability against degradable environmental conditions. The CdZnS/ZnS QDs finely emission-tunable in the range of 440–461 nm exhibit high photoluminescence (PL) quantum yields (QYs) of 81–92% along with an exceptionally narrow spectral bandwidth of 19 nm. These QDs are subjected to various post-treatments of a thorough purification cycle, long-term UV illumination, and hydrophobic-to-hydrophilic ligand exchange, each of which is usually detrimental to QD fluorescence. As a result, no noticeable deterioration in the fluorescent properties is observed, indicative of the insensitiveness of our CdZnS/ZnS QDs to the above degradable processes. Furthermore, PL properties of a solid film of multiple QD layers are assessed and compared with those of a diluted QD solution, showing an unprecedentedly small QY reduction of solid QD film versus QD solution. The above promising results are justified mainly by emphasizing the role of a thick ZnS shell present in CdZnS/ZnS QDs.

  10. Cell-wall-dependent effect of carboxyl-CdSe/ZnS quantum dots on lead and copper availability to green microalgae

    International Nuclear Information System (INIS)

    The present study examines the effect of carboxyl-CdSe/ZnS quantum dots (QDs) on Cu and Pb availability to microalgae with different cell wall characteristics: Chlorella kesslerii possessing a cellulosic cell wall and two strains of Chlamydomonas reinhardtii, a wall-less and a walled strain containing glycoproteins as the main cell wall component. Results demonstrated that QDs decreased Pb and Cu intracellular contents ({Cu}int and {Pb}int) in walled strains by a factor of 2.5 and 2, respectively, as expected by the decrease of about 70% and 40% in the dissolved Cu and Pb concentrations. QDs increased {Cu}int and {Pb}int in wall-less strain by a factor of 4 and 3.5. These observations were consistent with the observed association of QDs to the wall-less C. reinhardtii, and lack of association to walled algal strains. Suwannee River humic acid did not influence metal association to QDs, but decreased {Cu}int and {Pb}int in all microalgae. Highlights: ► Carboxyl-CdSe/ZnS quantum dots (QDs) affect metal availability to green microalgae. ► QDs decrease intracellular Cu and Pb in walled, but increase them in wall-less strain. ► QDs bind Cu and Pb and reduce their dissolved concentrations in exposure medium. ► QDs associate to wall-less strain, but not to the walled strains. ► Cell wall modulates the interaction of algae with QDs and carried toxic metals. - Carboxyl-CdSe/ZnS quantum dots decreased Cu and Pb intracellular contents in walled algal strains, however increased them in the wall-less strain.

  11. Growth and characterization of CdTe single quantum wells confined by Cd 1- xZn xTe alloy and short period CdTe/ZnTe superlattice

    Science.gov (United States)

    Magnea, N.; Lentz, G.; Mariette, H.; Feuillet, G.; Dal'bo, F.; Tuffigo, H.

    1989-02-01

    A comparative study of structural and optical properties of CdTe single quantum wells has been performed. Very efficient CdTe-Cd 1-xZn xTe (x Zn ≤ 0.2) wells have been grown and short period superlattices appear as a promising substitute of the alloy.

  12. A study on the purification of Zn from Pb splashing alloy

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jae Wook; Park, Seong Soo; Chung, Won Sub [Pusan National University, Pusan (Korea, Republic of); Kim, Yong Ha [Pukyong National University, Pusan (Korea, Republic of); Lee, Dae Yeol; Shin, Hyoung Ki [Research Institute of Industrial Science and Technology, Pohang (Korea, Republic of); Kim, Jin Han [Pusan Regional Small and Medium Business Office, Marine Equipment Test and Reserch Center, Pusan (Korea, Republic of)

    1997-12-31

    Electric arc furnace dust (EAF dust) generated in steel production based on scrap melting is contained Zn and Fe about 25 and 30 percent by weight, respectively. From a metallurgical point of view, the dust could be regarded as a raw material for Zn and Fe source. To recover the Zn in the metal from EAF dust, many system are proposed such as Arc Plasma Furnace and Pb splasher method. In this study, to recover high purity Zn from Pb splashing alloy, Zn distillation is carried out at the temperature of 1123, 1173, 1223, 1273 K, the gas flow rate of 2.5, 5.0, 8.0 Nl/min and the distilling time of 10, 30, 60, 90 minutes. The main results obtained from this study are as follows: (1) The amount of evaporated Zn and its evaporating rate increased with increasing temperature, but purity of Zn decreased with increasing temperature. Optimum temperature range was found out to be between 1173{approx}1223 K. (2) The amount of evaporated Zn and evaporation rate increased with increasing gas flow rate at a given temperature and distillation time. Gas flow rate has more influence over the amount of evaporated Zn and evaporation rate with increasing temperature. (author). 15 refs., 2 tabs., 12 figs.

  13. Correction of diagnostic x-ray spectra measured with CdTe and CdZnTe detectors

    Energy Technology Data Exchange (ETDEWEB)

    Matsumoto, M. [Osaka Univ., Suita (Japan). Medical School; Kanamori, H.; Toragaito, T.; Taniguchi, A.

    1996-07-01

    We modified the formula of stripping procedure presented by E. Di. Castor et al. We added the Compton scattering and separated K{sub {alpha}} radiation of Cd and Te (23 and 27keV, respectively). Using the new stripping procedure diagnostic x-ray spectra (object 4mm-Al) of tube voltage 50kV to 100kV for CdTe and CdZnTe detectors are corrected with comparison of those spectra for the Ge detector. The corrected spectra for CdTe and CdZnTe detectors coincide with those for Ge detector at lower tube voltage than 70kV. But the corrected spectra at higher tube voltage than 70kV do not coincide with those for Ge detector. The reason is incomplete correction for full energy peak efficiencies of real CdTe and CdZnTe detectors. (J.P.N.)

  14. [In situ immobilization of Pb and Cd in orchard soil using soil ameliorants].

    Science.gov (United States)

    Tang, Min; Zhang, Jin-Zhong; Zhang, Dan; Chen, Shun; Zhang, Xun; Liu, Wan-Ping; Yu, Jian

    2012-10-01

    In situ immobilization of Pb and Cd in soil of two gardens in Golden Orchard of Chongqing was studied using soil ameliorants, which included eight treatments: control, quicklime, superphosphate, organic manure, quicklime + superphosphate, quicklime + organic manure, superphosphate + organic manure, and quicklime + superphosphate + organic manure. The results showed that all ameliorant treatments could decrease soil acidity in both the loquat garden and peach garden except the superphosphate treatment. Compared with the control, the soil pH in the two gardens increased by 0. 93 and 0. 79 with quicklime treatment for 120 d, respectively. Ameliorant treatments could decrease the bioavailability of Pb and Cd in the soil, and thus reduce the contents of Pb and Cd in the fruits. The available Pb contents in the soil of loquat garden and peach garden significantly decreased after the 150 d treatment with quicklime and superphosphate, by 3.46% and 3.56%, respectively, and the Pb contents in loquat and peach decreased by 18.3% and 14.44%, respectively. The available Cd content in the soil of loquat garden decreased by 10. 95% after the 150 d treatment with quicklime. The available Cd content in the soil of peach garden decreased by 7.09% after the 150 d treatment with quicklime, superphosphate and organic manure. Ameliorant treatments could further decrease the Cd content in loquat, and the Cd contents in loquat and peach decreased by 30.91% and 24.62% with quicklime treatment, respectively. PMID:23233990

  15. Recent Progress in CdTe and CdZnTe Detectors

    CERN Document Server

    Takahashi, T; Takahashi, Tadayui; Watanabe, Shin

    2001-01-01

    Cadmium telluride (CdTe) and cadmium zinc telluride (CdZnTe) have been regarded as promising semiconductor materials for hard X-ray and Gamma-ray detection. The high atomic number of the materials (Z_{Cd} =48, Z_{Te} =52) gives a high quantum efficiency in comparison with Si. The large band-gap energy (Eg ~ 1.5 eV) allows us to operate the detector at room temperature. However, a considerable amount of charge loss in these detectors produces a reduced energy resolution. This problem arises due to the low mobility and short lifetime of holes. Recently, significant improvements have been achieved to improve the spectral properties based on the advances in the production of crystals and in the design of electrodes. In this overview talk, we summarize (1) advantages and disadvantages of CdTe and CdZnTe semiconductor detectors and (2) technique for improving energy resolution and photopeak efficiencies. Applications of these imaging detectors in future hard X-ray and Gamma-ray astronomy missions are briefly discus...

  16. One potential superlarge Pb-Zn ore occurrence with Himalayan thermal brine genesis--Wuqia Region, Xinjiang, China

    Institute of Scientific and Technical Information of China (English)

    刘继顺; 高珍权; 邓功全; 李明; 刘全德

    2002-01-01

    The paper focuses on geological and geochemical evidence of thermal brine genesis of Pb-Zn deposits in Wuqia district, Xinjiang. The results suggest that the known Pb-Zn deposits, such as Wulagen, are thermal brine genesis, which is supported by the features of tectonic setting, magma and regional metamorphism, and the characteristics of trace element distribution in strata and redistribution in the ore-forming process, the REE patterns and their main parameters of main type ores, the composition features and the source indicators of Pb, S isotopes. Ore-forming conditions of superlarge Pb-Zn deposits studies show that there exists tectonic and sources setting of Jinding-type superlarge Pb-Zn deposits in this area. Five Pb-Zn ore belts and central uplift belts discovered lately have not only confirmed that the genesis of Wulagen Pb-Zn deposits is thermal genesis, but also further proved that there exists tectonic and source setting of Jinding-type superlarge Pb-Zn deposit in the study area. Mineral deposit model was described and prospecting potentiality of superlarge Pb-Zn deposit and their significance were discussed.

  17. Distribution, origin, and transformation of metal and metalloid pollution in vegetable fields, irrigation water, and aerosols near a Pb-Zn mine.

    Science.gov (United States)

    Luo, Liqiang; Chu, Binbin; Liu, Ying; Wang, Xiaofang; Xu, Tao; Bo, Ying

    2014-01-01

    Pollution of arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), lead (Pb), and zinc (Zn) in vegetable fields was investigated near a Pb-Zn mine that has been exploited for over 50 years without a tailing reservoir. A total of 205 water, soil, and aerosol samples were taken and quantified by combined chemical, spectrometric, and mineral analytical methods. The pollution origins were identified by Pb isotopes and the pathways of transformation and transport of the elements and minerals was studied. The data showed that the vegetable fields were seriously polluted by As, Cd, and Pb. Some concentrations in the samples were beyond the regulatory levels and not suitable for agricultural activities. This study revealed that: (1) particulate matter is a major pollution source and an important carrier of mineral particles and pollutants; (2) the elements from the polluted water and soils were strongly correlated with each other; (3) Pb isotope ratios from the samples show that Pb minerals were the major pollution sources in the nearby vegetable fields, and the aerosols were the main carrier of mining pollution; (4) the alkaline, rich-carbonate, and wet conditions in this area promoted the weathering and transformation of galena into the secondary minerals, anglesite and cerussite, which are significant evidence of such processes; (5) the soil and the aerosols are a recycled secondary pollution source for each other when being re-suspended with wind.Highlights• Mining activities generated heavy metal pollution in fields around a Pb-Zn mine• The elements from water and soils are strongly correlated• Anglesite and cerussite are evidence of galena transformation into secondary minerals• Particulate matter is an important transport carrier of pollution. PMID:24687780

  18. Application of CdTe (CdZnTe) detectors for radioactive waste characterization

    CERN Document Server

    Dovbnya, N A; Kutny, V E

    2002-01-01

    The radiation detectors based on wide-zone semiconductor CdTe (CdZnTe) monocrystals have promising advantages for their application in investigation (characterization) of radioactive waste. Among these advantages there are the wide range of photons flux and energy, high registration efficiency and satisfactory energy resolution without deep cooling of the detector. This report discusses the obtained data concerning radiation stability of detectors, influence of different conditions (filters, collimators, registration channel fill etc.) on their energy resolution in spectrometric regime, as well as a dependence of radionuclide identification accuracy on detector size.

  19. Core-shell ITO/ZnO/CdS/CdTe nanowire solar cells

    International Nuclear Information System (INIS)

    Radial p-n junction nanowire (NW) solar cells with high densities of CdTe NWs coated with indium tin oxide (ITO)/ZnO/CdS triple shells were grown with excellent heterointerfaces. The optical reflectance of the devices was lower than for equivalent planar films by a factor of 100. The best efficiency for the NW solar cells was η = 2.49%, with current transport being dominated by recombination, and the conversion efficiencies being limited by a back contact barrier (ϕB = 0.52 eV) and low shunt resistances (RSH 2)

  20. Sorption selectivity of birnessite particle edges: a d-PDF analysis of Cd(ii) and Pb(ii) sorption by δ-MnO2 and ferrihydrite.

    Science.gov (United States)

    van Genuchten, Case M; Peña, Jasquelin

    2016-08-10

    Birnessite minerals (layer-type MnO2), which bear both internal (cation vacancies) and external (particle edges) metal sorption sites, are important sinks of contaminants in soils and sediments. Although the particle edges of birnessite minerals often dominate the total reactive surface area, especially in the case of nanoscale crystallites, the metal sorption reactivity of birnessite particle edges remains elusive. In this study, we investigated the sorption selectivity of birnessite particle edges by combining Cd(ii) and Pb(ii) adsorption isotherms at pH 5.5 with surface structural characterization by differential pair distribution function (d-PDF) analysis. We compared the sorption reactivity of δ-MnO2 to that of the nanomineral, 2-line ferrihydrite, which exhibits only external surface sites. Our results show that, whereas Cd(ii) and Pb(ii) both bind to birnessite layer vacancies, only Pb(ii) binds extensively to birnessite particle edges. For ferrihydrite, significant Pb(ii) adsorption to external sites was observed (roughly 20 mol%), whereas Cd(ii) sorption was negligible. These results are supported by bond valence calculations that show comparable degrees of saturation of oxygen atoms on birnessite and ferrihydrite particle edges. Therefore, we propose that the sorption selectivity of birnessite edges follows the same order of that reported previously for ferrihydrite: Ca(ii) < Cd(ii) < Ni(ii) < Zn(ii) < Cu(ii) < Pb(ii). PMID:27183472

  1. Aqueous synthesis of high-fluorescence CdZnTe alloyed quantum dots

    International Nuclear Information System (INIS)

    Highlights: • We have synthesized the CdZnTe QDs with a Zn/Cd molar ratio from 1 to 7. • The reaction was happened in weak acid condition. • The fluorescence emitting peak was continuously tunable from 490 nm to 660 nm. • The maximum quantum yield of our synthesized CdZnTe QDs has reached 78.97%. • Our sample showed excellent stability against time. -- Abstract: High luminescent CdZnTe quantum dots (QDs) were synthesized by a one-step aqueous method using 3-mercapto propionic acid (MPA) as a stabilizer. The as-prepared samples are in good homogeneity and dispersity with an average particle size of 5 nm. Accordingly, the size and composition-dependent fluorescent emission wavelength of the resultant CdZnTe alloyed QDs can be continuously tuned from 490 to 660 nm. Compared with the difficult acquisition of CdZnTe QDs with a high Zn/Cd molar ratio in alkaline condition, CdZnTe QDs with a Zn/Cd molar ratio from 1 to 7 has been obtained in weak acid condition by adjusting the pH value of precursor solution. The maximum quantum yield has reached nearly 80% without any post-treatment. And it also showed excellent stability against time

  2. Prototype Imaging Cd-Zn-Te Array Detector

    OpenAIRE

    Bloser, P. F.; Narita, T; Grindlay, J. E.; Shah, K.

    1998-01-01

    We describe initial results of our program to develop and test Cd-Zn-Te (CZT) detectors with a pixellated array readout. Our primary interest is in the development of relatively thick CZT detectors for use in astrophysical coded aperture telescopes with response extending over the energy range $\\sim 10-600$ keV. The coded aperture imaging configuration requires only relatively large area pixels (1-3 mm), whereas the desired high energy response requires detector thicknesses of at least 3-5 mm...

  3. Sorption Potentials of Waste Tyre for Some Heavy Metals (Pb Cd) in Aqueous Solution

    OpenAIRE

    Austin Kanayo ASIAGWU; Patrice-Anthony-Chudi OKOYE; Orji IFEOMA; Patrick Ejo OMUKU

    2009-01-01

    An investigation into the adsorption potential of activated and inactivated waste tyre powders for some heavy metals (Pb2+ and Cd2+) in their aqueous solution has been studied. The result indicated that inactivated waste tyre is a good non-conventional adsorbent for the removal of Cd from aqueous solution. A total of 93.3% of Cadmium contents was removed. The inactivated waste type proved a good adsorbent for the removal of Pb2+ 5g of 500mm activated tyre removed over 86.66% of Pb2+ from solu...

  4. Sorption Potentials of Waste Tyre for Some Heavy Metals (Pb Cd in Aqueous Solution

    Directory of Open Access Journals (Sweden)

    Austin Kanayo ASIAGWU

    2009-07-01

    Full Text Available An investigation into the adsorption potential of activated and inactivated waste tyre powders for some heavy metals (Pb2+ and Cd2+ in their aqueous solution has been studied. The result indicated that inactivated waste tyre is a good non-conventional adsorbent for the removal of Cd from aqueous solution. A total of 93.3% of Cadmium contents was removed. The inactivated waste type proved a good adsorbent for the removal of Pb2+ 5g of 500mm activated tyre removed over 86.66% of Pb2+ from solution.

  5. Synthesis and photocatalytic activity of three-dimensional ZnS/CdS composites

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Shuling, E-mail: liusl8888@yahoo.com.cn; Li, Honglin; Yan, Lu

    2013-09-01

    Graphical abstract: - Highlights: • 3D urchin-like ZnS/CdS composites were synthesized via a two-step method. • The CdS nanoparticles were assembled on the thorns of 3D ZnS urchins. • The ZnS/CdS composites show excellent photocatalytic degradation activities. • The modification of CdS on ZnS is responsible for the enhanced property. - Abstract: Urchin-like ZnS/CdS semiconductor composites were successfully synthesized by combining solvothermal route with homogeneous precipitation process. The as-obtained samples were characterized by means of XRD, EDX, TEM, HR-TEM, ED and FE-SEM techniques. The results show that the as-obtained composites were comprised of the hexagonal structure ZnS and CdS, and CdS nanoparticles were assembled on the surfaces of the thorns of urchin-like ZnS. In addition, the optical properties and photocatalytic activities of the as-prepared ZnS/CdS composites toward some organic dyes (such as Methyl Orange, Pyronine B, Rhodamine B and Methylene Blue) were separately investigated. It is found that the ZnS/CdS composites exhibit excellent photocatalytic degradation activity for these dyes under UV irradiation, as compared to corresponding pure ZnS urchins and commercial anatase TiO{sub 2} (P-25). This enhanced activity may be related to the modification of CdS nanoparticles on the surfaces of thorns of ZnS urchins and a tentative mechanism for the enhanced photocatalytic degradation activities of the ZnS/CdS composite catalyst was proposed.

  6. Biomonitoring potential of five sympatric Tillandsia species for evaluating urban metal pollution (Cd, Hg and Pb)

    Science.gov (United States)

    Sánchez-Chardi, Alejandro

    2016-04-01

    The present study quantifies non essential heavy metals highly toxic for biological systems (Pb, Hg and Cd) in five autochthonous epiphytic plants from Tillandsia genus (T. recurvata, T. meridionalis, T. duratii, T. tricholepis, T. loliacea) according to different traffic levels (reference, low, medium and high polluted sites) in Asunción (Paraguay). The three metals increased in polluted sites following Pb (till 62.99 ppm in T. tricholepis) > Cd (till 1.35 ppm in T. recurvata) > Hg (till 0.36 ppm in T. recurvata) and Pb and Cd levels were directly related to traffic flow. Although the species showed similar bioaccumulation pattern (namely, higher levels of metals in polluted sites), enrichment factors (maximum EF values 37.00, 18.16, and 11.90 for Pb, Hg, and Cd, respectively) reported T. tricholepis as the most relevant bioindicator due to its wide distribution and abundance in study sites, low metal content in control site and high metal contents in polluted sites, and significant correlations with traffic density of Pb and Cd. This study emphasizes the necessity of biomonitoring air pollution in areas out of air monitoring control such as Asunción, where the high levels of metal pollution especially Pb, may represent an increment of risk for the human population inhabiting this urban area.

  7. Aqueous CdPbS quantum dots for near-infrared imaging

    Science.gov (United States)

    Au, Giang H. T.; Y Shih, Wan; Tseng, S.-Ja; Shih, Wei-Heng

    2012-07-01

    Quantum dots (QDs) are semiconducting nanocrystals that have photoluminescent (PL) properties brighter than fluorescent molecules and do not photo-bleach, ideal for in vivo imaging of diseased tissues or monitoring of biological processes. Near-infrared (NIR) fluorescent light within the window of 700-1000 nm, which is separated from the major absorption peaks of hemoglobin and water, has the potential to be detected several millimeters under the surface with minimal interference from tissue autofluorescence. Here we report the synthesis and bioimaging demonstration of a new NIR QDs system, namely, CdPbS, made by an aqueous approach with 3-mercaptopropionic acid (MPA) as the capping molecule. The aqueous-synthesized, MPA-capped CdPbS QDs exhibited an NIR emission in the range of 800-950 nm with xi ≥ 0.3, where xi denotes the initial Pb molar fraction during the synthesis. Optimal PL performance of the CdPbS QDs occurred at xi = 0.7, which was about 4 nm in size as determined by transmission electron microscopy, had a rock salt structure and a quantum yield of 12%. Imaging of CdPbS QDs was tested in membrane staining and transfection studies. Cells transfected with CdPbS QDs were shown to be visible underneath a slab of chicken muscle tissue of up to 0.7 mm in thickness without the use of multiple-photon microscopy.

  8. Aqueous CdPbS quantum dots for near-infrared imaging

    International Nuclear Information System (INIS)

    Quantum dots (QDs) are semiconducting nanocrystals that have photoluminescent (PL) properties brighter than fluorescent molecules and do not photo-bleach, ideal for in vivo imaging of diseased tissues or monitoring of biological processes. Near-infrared (NIR) fluorescent light within the window of 700–1000 nm, which is separated from the major absorption peaks of hemoglobin and water, has the potential to be detected several millimeters under the surface with minimal interference from tissue autofluorescence. Here we report the synthesis and bioimaging demonstration of a new NIR QDs system, namely, CdPbS, made by an aqueous approach with 3-mercaptopropionic acid (MPA) as the capping molecule. The aqueous-synthesized, MPA-capped CdPbS QDs exhibited an NIR emission in the range of 800–950 nm with xi ≥ 0.3, where xi denotes the initial Pb molar fraction during the synthesis. Optimal PL performance of the CdPbS QDs occurred at xi = 0.7, which was about 4 nm in size as determined by transmission electron microscopy, had a rock salt structure and a quantum yield of 12%. Imaging of CdPbS QDs was tested in membrane staining and transfection studies. Cells transfected with CdPbS QDs were shown to be visible underneath a slab of chicken muscle tissue of up to 0.7 mm in thickness without the use of multiple-photon microscopy. (paper)

  9. PbS/Cd3P2 quantum heterojunction colloidal quantum dot solar cells

    International Nuclear Information System (INIS)

    Here, we demonstrated the quantum heterojunction colloidal quantum dot (CQD) solar cells employing the PbS CQDs/Cd3P2 CQDs architecture in which both the p-type PbS and n-type Cd3P2 CQD layers are quantum-tunable and solution-processed light absorbers. We synthesized well-crystallized and nearly monodispersed tetragonal Cd3P2 CQDs and then engineered their energy band alignment with the p-type PbS by tuning the dot size and hence the bandgap to achieve efficient light absorbing and charge separation. We further optimized the device through the Ag-doping strategy of PbS CQDs that may leverage an expanded depletion region in the n-layer, which greatly enhances the photocurrent. The resulting devices showed an efficiency of 1.5%. (paper)

  10. ZnO@CdS Core-Shell Heterostructures: Fabrication, Enhanced Photocatalytic, and Photoelectrochemical Performance

    Science.gov (United States)

    Ding, Meng; Yao, Nannan; Wang, Chenggang; Huang, Jinzhao; Shao, Minghui; Zhang, Shouwei; Li, Ping; Deng, Xiaolong; Xu, Xijin

    2016-04-01

    ZnO nanorods and ZnO@CdS heterostructures have been fabricated on carbon fiber cloth substrates via hydrothermal and electrochemical deposition. Their photocatalytic properties were investigated by measuring the degradation of methylene blue under ultraviolet light irradiation. The result illustrated that the photodegradation efficiency of ZnO@CdS heterostructures was better than that of pure ZnO nanorods, in which the rate constants were about 0.04629 and 0.02617 min-1. Furthermore, the photocurrent of ZnO@CdS heterostructures achieved 102 times enhancement than pure ZnO nanorods, indicating that more free carriers could be generated and transferred in ZnO@CdS heterostructures, which could be responsible for the increased photocatalytic performance.

  11. ZnO@CdS Core-Shell Heterostructures: Fabrication, Enhanced Photocatalytic, and Photoelectrochemical Performance.

    Science.gov (United States)

    Ding, Meng; Yao, Nannan; Wang, Chenggang; Huang, Jinzhao; Shao, Minghui; Zhang, Shouwei; Li, Ping; Deng, Xiaolong; Xu, Xijin

    2016-12-01

    ZnO nanorods and ZnO@CdS heterostructures have been fabricated on carbon fiber cloth substrates via hydrothermal and electrochemical deposition. Their photocatalytic properties were investigated by measuring the degradation of methylene blue under ultraviolet light irradiation. The result illustrated that the photodegradation efficiency of ZnO@CdS heterostructures was better than that of pure ZnO nanorods, in which the rate constants were about 0.04629 and 0.02617 min(-1). Furthermore, the photocurrent of ZnO@CdS heterostructures achieved 10(2) times enhancement than pure ZnO nanorods, indicating that more free carriers could be generated and transferred in ZnO@CdS heterostructures, which could be responsible for the increased photocatalytic performance. PMID:27090656

  12. Leaching potential of pervious concrete and immobilization of Cu, Pb and Zn using pervious concrete

    Science.gov (United States)

    Solpuker, U.; Sheets, J.; Kim, Y.; Schwartz, F. W.

    2014-06-01

    This paper investigates the leaching potential of pervious concrete and its capacity for immobilizing Cu, Pb and Zn, which are common contaminants in urban runoff. Batch experiments showed that the leachability of Cu, Pb and Zn increased when pH pervious concrete might function to attenuate contaminant migration. A porous concrete block was sprayed with low pH water (pH = 4.3 ± 0.1) for 190 h. The effluent was highly alkaline (pH ~ 10 to 12). In the first 50 h, specific conductance and trace-metal were high but declined towards steady state values. PHREEQC modeling showed that mixing of interstitial alkaline matrix waters with capillary pore water was required in order to produce the observed water chemistry. The interstitial pore solutions seem responsible for the high pH values and relatively high concentrations of trace metals and major cations in the early stages of the experiment. Finally, pervious concrete was sprayed with a synthetic contaminated urban runoff (10 ppb Cu, Pb and Zn) with a pH of 4.3 ± 0.1 for 135 h. It was found that Pb immobilization was greater than either Cu or Zn. Zn is the most mobile among three and also has the highest variation in the observed degree of immobilization.

  13. Cd and Pb extractability with EDTA in sediments of three contrasted sites of the Lebanese coast

    International Nuclear Information System (INIS)

    Cd and Pb extractability with EDTA were measured from sediment samples collected at three contrasted sites along the Lebanese coastal zones: Akkar, Dora and Selaata. Akkar is located away from any direct source of contamination, while Dora and Selaata receive respectively urban and industrial wastes. The extractability of Cd and Pb from sediments of the aforementioned sites was studied by applying kinetic and equilibrium extractions with EDTA 0.05M. The adjustment of Pb kinetic extractions curves to a two-first order reactions model permitted to kinetically fractionate Pb in the studied sediments into three fractions (readily extractable, less extractable and non extractable) and allowed to conclude that Pb in Selaata represents the highest environmental risk. (author)

  14. Novel red-emission of ternary ZnCdSe semiconductor nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Shu-Ru, E-mail: srchung@nfu.edu.tw [National Formosa University, Graduate Institute of Materials Science and Green Energy Engineering (China); Wang, Kuan-Wen [National Central University, Institute of Materials Science and Engineering (China); Chen, Hong-Shuo; Chen, Hong-Hong [National Formosa University, Graduate Institute of Materials Science and Green Energy Engineering (China)

    2015-02-15

    The effect of chain lengths of fatty acids on the physical properties of CdSe and ZnCdSe semiconductor nanocrystals (NCs) synthesized by the colloidal chemistry procedure is investigated. The fatty acids, lauric acid (LA), and stearic acid (SA), with different lengths of carbon chains, are used to prepare CdSe and ZnCdSe NCs when hexyldecylamine (HDA) is applied as the sole surfactant. For CdSe–SA and ZnCdSe–SA, they have the same emission wavelength at 592 nm and the same particle size of 3.3 nm; however, their quantum yield (QY) is 75 and 16 %, respectively. In contrast, the emission wavelength of CdSe–LA and ZnCdSe–LA NCs is 609 and 615 nm, the particle size is about 3.5 and 4 nm under the same reaction time, and the QY of them are 33 and 59 %, respectively. The X-ray diffraction pattern shows that ZnCdSe NCs all have the wurtzite structure, and their main peaks are located between those of pure CdSe and ZnSe materials. The main phase of ZnCdSe–SA and ZnCdSe–LA is ZnSe and CdSe, respectively, implying that alloyed ZnCdSe NC can be prepared and ZnSe and CdSe phase can be promoted by SA and LA, respectively. Moreover, the QY of red-emission ZnCdSe–LA is higher than 50 %. These results suggest that the growth rate of CdSe as well as ZnCdSe NC can be enhanced by using LA as complex reagent and HDA as sole surfactant. It is expected that the reported effective synthetic strategy can be developed as a very practical, easy and not time-consuming approach to prepare red emissive NCs with high QY and high reproducibility.

  15. Characterization of Aerosols Containing Zn, Pb, and Cl from an Industrial Region of Mexico City

    International Nuclear Information System (INIS)

    During the March, 2006 MILAGRO campaign, measurements in the Northern Mexico City Metropolitan Area revealed the frequent appearance of particles with a characteristically high content of internally mixed Zn, Pb, Cl, and P. A comprehensive study of the chemical and physical properties of these particles was performed using a complementary combination of aerosol measurement techniques. Individual particles were analyzed using Aerosol Time-of-Flight Mass Spectrometry (ATOFMS) and Computer Controlled Scanning Electron Microscopy/Energy Dispersive X-Ray spectroscopy (CCSEM/EDX). Proton Induced X-Ray Emission (PIXE) analysis of bulk aerosol samples provided time-resolved mass concentrations of individual elements. The PIXE measurements indicated that Zn is more strongly correlated with Cl than with any other element and that Zn concentrations are higher than other non-ferrous transition metals. The Zn- and Pb-containing particles have both spherical and non-spherical morphologies. Many metal rich particles had needle-like structures and were found to be composed of ZnO and/or Zn(NO3)2 6H2O as indicated by scanning transmission x-ray microscopy/near edge X-ray absorption spectroscopy (STXM/NEXAFS). The Zn and Pb rich particles were primarily in the submicron size range and internally mixed with elemental carbon. The unique chemical associations most closely match signatures acquired for garbage incineration. This unique combination of complementary analytical techniques has allowed for a comprehensive evaluation of Zn- and Pb- containing particles in a complex urban environment, highlighting unique characteristics that give powerful insight into their origin

  16. Interrelationships between Cd, Zn and birth weight in neonates of women who smoke

    International Nuclear Information System (INIS)

    A study was designed to test the hypothesis that the increased cadmium level in pregnant women who smoke alters the metabolism of zinc in the maternal-fetal unit, and that this altered Zn metabolism may contribute to lower birth weight infants. One hundred-thirty mother/infant pairs were studied. Maternal whole blood and placental Cd were analyzed by graphite furnace atomic absorption spectrophotometry; maternal and fetal plasma, red blood cell and placental Zn by flame atomic absorption spectroscopy. Maternal plasma thiocyanate (SCN) levels were used as an index of smoking status. Zn intake was estimated by diet history in a subgroup of 34 patients. The data were analyzed using t-tests, correlation and stepwise multiple regression techniques. No differences in Zn intake were found between pregnant women who smoked and those who did not. The average daily intake of Zn was 10.2 +/- 5 mg; this is less than the RDA for Zn during pregnancy. The data show that there are significant positive correlations between SCN levels and levels of whole blood Cd, placental Cd, and placental Zn. Cord vein samples from infants of mothers who smoked had decreased red blood cell Zn. This was particularly true in nulliparous patients. In all patients, maternal whole blood Cd was found to be negatively related to birth weight and cord vein red blood cell Zn was positively related to birth weight. The results support the hypothesis of a Cd-Zn interaction in pregnant women who smoke. Additional findings suggest an effect of parity on the interaction between Cd and Zn. Placental Cd was found to be negatively related to birth weight in nulliparous patients (n=21). In multiparous patients (n=109) placental Zn was inversely related to birth weight. In patients with parity 2 or greater (n=54), placental Cd was directly predictive of placental Zn. These results may reflect a less favorable Zn nutritional status with increasing parity

  17. Direct characterization of polymer encapsulated CdSe/CdS/ZnS quantum dots

    Science.gov (United States)

    Zorn, Gilad; Dave, Shivang R.; Weidner, Tobias; Gao, Xiaohu; Castner, David G.

    2016-06-01

    Surface engineering advances of semiconductor quantum dots (QDs) have enabled their application to molecular labeling, disease diagnostics and tumor imaging. For biological applications, hydrophobic core/shell QDs are transferred into aqueous solutions through the incorporation of water-solubility imparting moieties, typically achieved via direct exchange of the native surface passivating ligands or indirectly through the adsorption of polymers. Although polymeric encapsulation has gained wide acceptance, there are few reports addressing the characterization of the adsorbed polymers and existing theoretical analyses are typically based on simple geometric models. In this work, we experimentally characterize and quantify water-soluble QDs prepared by adsorption of amphiphilic poly(maleic anhydride-alt-1-tetradecene) (PMAT, MW ~ 9000) onto commercially available CdSe/CdS/ZnS (CdSe/CdS/ZnS-PMAT). Using X-ray photoelectron spectroscopy (XPS) we determined that ~ 15 PMAT molecules are adsorbed onto each QD and sum frequency generation (SFG) vibrational spectra were utilized to investigate the mechanism of interaction between PMAT molecules and the QD surface. Importantly, when employed together, these techniques constitute a platform with which to investigate any polymer-nanoparticle complex in general.

  18. ADVANCED READOUT ELECTRONICS FOR MULTIELEMENT CdZnTe SENSORS.

    Energy Technology Data Exchange (ETDEWEB)

    DE GERONIMO,G.; O CONNOR,P.; KANDASAMY,A.; GROSHOLZ,J.

    2002-07-08

    A generation of high performance front-end and read-out ASICs customized for highly segmented CdZnTe sensors is presented. The ASICs, developed in a multi-year effort at Brookhaven National Laboratory, are targeted to a wide range of applications including medical, safeguards/security, industrial, research, and spectroscopy. The front-end multichannel ASICs provide high accuracy low noise preamplification and filtering of signals, with versions for small and large area CdZnTe elements. They implement a high order unipolar or bipolar shaper, an innovative low noise continuous reset system with self-adapting capability to the wide range of detector leakage currents, a new system for stabilizing the output baseline and high output driving capability. The general-purpose versions include programmable gain and peaking time. The read-out multichannel ASICs provide fully data driven high accuracy amplitude and time measurements, multiplexing and time domain derandomization of the shaped pulses. They implement a fast arbitration scheme and an array of innovative two-phase offset-free rail-to-rail analog peak detectors for buffering and absorption of input rate fluctuations, thus greatly relaxing the rate requirement on the external ADC. Pulse amplitude, hit timing, pulse risetime, and channel address per processed pulse are available at the output in correspondence of an external readout request. Prototype chips have been fabricated in 0.5 and 0.35 {micro}m CMOS and tested. Design concepts and experimental results are discussed.

  19. CdTe and CdZnTe crystals for room temperature gamma-ray detectors

    CERN Document Server

    Franc, J; Belas, E; Grill, R; Hlidek, P; Moravec, P; Bok, J B

    1999-01-01

    CdTe(Cl) detectors from CdTe single crystals, grown by the Bridgman method from Te-rich melt, were fabricated. The quality of the detectors was tested with sup 5 sup 7 Co and sup 2 sup 4 sup 1 Am sources. In the sup 5 sup 7 Co spectrum low noise is demonstrated by the presence of a 14 keV peak and good resolution approx 7 keV (FWHM) evident from the separation of 122 and 136 keV peaks. A review is given of the state-of-the-art properties of (CdZn)Te single crystals prepared for substrates in the Institute of Physics of Charles University. The quality of samples is tested by measurements of the diffusion length of minority carriers, from which the mobility-lifetime product is evaluated. (author)

  20. The ‘sub’ metallide oxide hydrides Sr{sub 21}Si{sub 2}O{sub 5}H{sub 12+x} and Ba{sub 21}M{sub 2}O{sub 5}H{sub 12+x} (M = Zn, Cd, Hg, In, Tl, Si, Ge, Sn, Pb, As, Sb, Bi)

    Energy Technology Data Exchange (ETDEWEB)

    Jehle, Michael; Hoffmann, Anke [Institut für Anorganische und Analytische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstr. 21, D-79104 Freiburg (Germany); Kohlmann, Holger [Institut für Anorganische Chemie, Universität Leipzig, Johannisallee 29, D-04103 Leipzig (Germany); Scherer, Harald [Institut für Anorganische und Analytische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstr. 21, D-79104 Freiburg (Germany); Röhr, Caroline, E-mail: caroline@ruby.chemie.uni-freiburg.de [Institut für Anorganische und Analytische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstr. 21, D-79104 Freiburg (Germany)

    2015-02-25

    Highlights: • The sub metallide oxide hydrides (Sr/Ba){sub 21}M{sub 2}O{sub 5}H{sub 12+x} were prepared for 14 M elements. • M covers a wide range of elements, from the Zn group to the pentels. • The ionic partial structure contains isolated M anions and suboxide clusters [O{sub 5}A{sub 18}]. • The H-content was determined by neutron diffraction and {sup 1}H/{sup 2}D MAS-NMR spectroscopy. • Band structure calculations support the H/D content and distribution. - Abstract: The title compounds sporting a great variety of anions M of different formal charges have been synthesized from melts of the composition A:M:O:H/D = 21:2:5:24, using BaH{sub 2}/SrH{sub 2} as hydrogen sources. All phases were characterized by means of single crystal X-ray data [cubic, space group Fd3{sup ¯}m; Sr{sub 21}Si{sub 2}O{sub 5}H{sub 12+x}: a = 1911.90(1) pm, R1 = 0.0201; for the barium phases with Zn (a = 2041.7(3) pm, R1 = 0.077), Cd (a = 2063.3(1) pm, R1 = 0.051), Hg (a = 2050.7(1) pm, R1 = 0.059), In (a = 2060.7(1) pm, R1 = 0.101), Tl (a = 2068.1(10) pm, R1 = 0.0485), Si (a = 2033.6(1) pm, R1 = 0.045), Ge (a = 2035.6(1) pm, R1 = 0.037), Sn (a = 2053.2(2) pm, R1 = 0.054), Pb (a = 2059.7(1) pm, R1 = 0.056), As (a = 2023.0(3) pm, R1 = 0.087), Sb (a = 2041.9(1) pm, R1 = 0.067) and Bi (a = 2045.9(1) pm, R1 = 0.075)]. Neutron powder diffraction data collected for the Ba silicide (both H and D compound) were refined by the Rietveld method (a = 2037.0(1), R{sub p} = 0.0173; wR{sub p} = 0.0304, R(F{sup 2}) = 0.086). The statistically occupied (H/D)(1) site 96g, which corresponds to the carbon position inSr{sub 21}Si{sub 2}O{sub 5}C{sub 6}, together with two further sparsely occupied sites (H/D)(2,3), yields the overall composition Ba{sub 21}Si{sub 2}O{sub 5}D{sub 14}. The hydrogen content, its chemical character and the distribution among the three H/D positions was evaluated by {sup 1}H/{sup 2}H MAS NMR spectroscopy for the Si, Ge and Sb compound. The crystal structure exhibits two

  1. CdTe and ZnTe metal interface formation and Fermi-level pinning

    Science.gov (United States)

    Wahi, A. K.; Carey, G. P.; Chiang, T. T.; Lindau, I.; Spicer, W. E.

    1989-01-01

    Interfacial morphology and Fermi-level pinning behavior at the interfaces of Al, Ag, and Pt with UHV-cleaved CdTe and ZnTe are studied using X-ray photoelectron and ultraviolet photoemission spectroscopies. Results are compared to metal/HgCdTe interface formation. For Al/CdTe, a case is found where significantly greater intermixing occurs in CdTe than seen on HgCdTe. The Al/ZnTe interface is also more abrupt than Al/CdTe. Band bending results for interfaces of all three metals with p-CdTe and p-ZnTe are presented and implications for metal/HgZnTe interface formation are considered.

  2. Growth, characterization and transport properties of PbZn1−S mixed crystals

    Indian Academy of Sciences (India)

    M Nagabhushana; E Nagabushan; D Jaya Prakash; B Rajam; K Yadaiah

    2012-08-01

    The polycrystalline PbZn1−S semiconductor powder with (0 ≤ ≤ 0.5) has been prepared by controlled co-precipitation method from an alkaline medium using thiourea as a sulphide ion source. Pellets are made with these powders applying 10 ton/sq cm pressure and sintered at 800 °C for 2 h in nitrogen atmosphere. X-ray studies of these samples have indicated that the compounds are polycrystalline in nature with mixed hexagonal and cubic structure of ZnS and cubic structure of PbS. Lattice parameters ( and ) of all the compounds are determined from the X-ray data and are found to decrease non-linearly with increase in Pb concentration (). It is also observed that the grain size of the crystallites increases in samples with = 0–0.5. Scanning electron micrographs have shown that both cubic and hexagonal crystallites are present in the mixed crystals. The electrical conductivity in PbZn1−S is found to decrease with increase in composition ( = 0–0.5), whereas it increases at all temperatures in all samples. Mobility of charge carrier concentration is found to increase with increasing temperature. The increase in carrier mobility in PbZn1−S samples may be due to reduced grain boundary potential. In PbZn1−S samples with = 0–0.3, sum of the activation energy due to charge carriers and grain boundary potential is equal to the activation energy due to conductivity.

  3. Growth, characterization and transport properties of PbZn1–S mixed crystals

    Indian Academy of Sciences (India)

    M Nagabhushanam; E Nagabushan; D Jaya Prakash; B Rajam; K Yadaiah

    2009-02-01

    The polycrystalline PbZn1–S semiconductor powder with (0 ≤ ≤ 0.5) has been prepared by controlled co-precipitation method from an alkaline medium using thiourea as a sulphide ion source. Pellets are made with these powders applying 10 ton/sq.cm. pressure and sintered at 800°C for 2 h in nitrogen atmosphere. X-ray studies of these samples have indicated that the compounds are polycrystalline in nature with mixed hexagonal and cubic structure of ZnS and cubic structure of PbS. Lattice parameters ( and ) of all the compounds are determined from the X-ray data and are found to decrease nonlinearly with increase in Pb concentration (). It is also observed that the grain size of the crystallites increases in samples with = 0–0.5. Scanning electron micrographs have shown that both cubic and hexagonal crystallites are present in the mixed crystals. The electrical conductivity in PbZn1–S is found to decrease with increase in composition ( = 0–0.5), whereas it increases at all temperatures in all samples. Mobility of charge carrier concentration is found to increase with increasing temperature. The increase in carrier mobility in PbZn1–S samples may be due to reduced grain boundary potential. In PbZn1–S samples with = 0–0.3, the sum of the activation energy due to charge carriers and grain boundary potential is equal to the activation energy due to conductivity.

  4. Temperature dependence of nanostructure in PbSe–ZnSe composite thin film

    International Nuclear Information System (INIS)

    The nanostructure of PbSe–ZnSe composite thin films prepared by the hot-wall deposition (HWD) method was investigated using small-angle x-ray (SAXS) scattering. The SAXS profiles indicate the formation of two kinds of nanoparticles: large nanoparticles that vanish and small particles that increase in size with increasing temperature. At high substrate temperatures, the volume fraction of all the nanoparticles estimated from SAXS is consistent with that of PbSe obtained by chemical analysis. This shows that PbSe forms nanoparticles at high substrate temperatures. On the other hand, the same analysis for the volume fraction at low substrate temperatures reveals that the chemical composition of the nanoparticles differs from PbSe. Pb nanoparticles are probably formed at low substrate temperatures and disappear with increasing substrate temperature. (paper)

  5. Stable core/shell CdTe/Mn-CdS quantum dots sensitized three-dimensional, macroporous ZnO nanosheet photoelectrode and their photoelectrochemical properties.

    Science.gov (United States)

    Li, Weili; Sheng, Pengtao; Feng, Hongyan; Yin, Xuehua; Zhu, Xuewei; Yang, Xu; Cai, Qingyun

    2014-08-13

    A novel photoelectrode based on ZnS/CdTe/Mn-CdS/ZnS-sensitized three-dimensional macroporous ZnO nanosheet (NS) has been prepared by electrodeposition and successive ion layer adsorption and reaction (SILAR) method. The photoelectrode performances were significantly improved through the coupling of the core/shell CdTe/Mn-CdS quantum dots (QDs) with ZnO NS, and the introduction of the ZnS layer as a potential barrier. The photocurrent density systematically increases from ZnO NS (0.45 mA/cm(2)), CdTe/Mn-CdS/ZnO NS (4.98 mA/cm(2)), to ZnS/CdTe/Mn-CdS/ZnS/ZnO (6.23 mA/cm(2)) under the irradiation of AM 1.5G simulated sunlight. More important, the ZnS/CdTe/Mn-CdS/ZnS-sensitized ZnO NS photoelectrode provides a remarkable photoelectrochemical cell efficiency of 4.20% at -0.39 V vs Ag/AgCl. PMID:25010851

  6. APPLICATION OF THE ANNEXATION PRINCIPLE TO THE STUDYOF THERMODYNAMIC PROPERTIES OF TERNARY METALLICMELTS Cd-Pb-Sb

    Institute of Scientific and Technical Information of China (English)

    J. Zhang

    2001-01-01

    Based on the phase diagrams, measured activities and the annexation principle, the calculating models of mass action concentrations for Cd-Pb, Pb-Sb and Cd-Sb binary as well as Cd-Pb-Sb ternary metallic melts have been formulated. The results of calculation both agree with practice and obey the mass action law. This in turn testifies that the models formulated can reflect the structural reality of corresponding melts and the annexation principle is applicable to these melts.``

  7. Effects of Cd2+ and Pb2+ on the substrate biofilms in the integrated vertical-flow constructed wetland

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jinlian; CHENG Shuiping; HE Feng; LIANG Wei; WU Zhenbin

    2008-01-01

    The effects of single Cd2+ and Pb2+ and combined Cd2+ and Pb2+ on dehydrogenase activity and polysaccharide content of the substrate biofilms in the integrated vertical-flow constructed wetland (IVCW) were studied. Dehydrogenase activities decreased linearly with the increasing concentrations of Cd2+ and Pb2+ at different times (6, 24, 72, and 120 h). The activities at both 6 and 24 h were significantly higher than that at 72 and 120 h in the case of single and combined treatments. The single Cd2+ and Pb2+ treatments significantly inhibited dehydrogenase activities at concentrations in excess of 20 μmol/L Cd2+ (equal to 2.24 mg/L Cd2+) and 80 μmol/L Pb2+ (equal to 16.56 mg/L Pb2+), respectively. The inhibitory effect of Cd2+ was much greater than that of Pb2+. At the same time, the combined treatment of Cd2+ and Pb2+ significantly inhibited dehydrogenase activities at all five concentrations studied and the lowest combined concentration was 1.25 μmol/L Cd2+ and 5 μmol/L Pb2+ (equal to 0.14 mg/L Cd2+ and 1.04 mg/L Pb2+). A synergistic effect of Cd2+ and Pb2+ was observed. On the other hand, polysaccharide contents varied unpredictably with the increasing concentrations of Cd2+ and Pb2+ and extended experimental time. There were no significant statistical differences within the range of concentration and time studied, whether singly or in combination. These results implied that the effects of heavy metals on biofilms should be a concern for the operation and maintenance of constructed wetlands.

  8. Synthesis and characterization of Sn-doped CdZnS nanoparticles

    Indian Academy of Sciences (India)

    R Shrivastava; S C Shrivastava

    2015-09-01

    Tin (Sn)-doped cadmium zinc sulphide nanoparticles (CdZnS : Sn) were synthesized by the chemical bath deposition method with two different concentrations of Sn (2 and 4 mol%). X-ray diffraction (XRD) pattern reveals the formation of CdZnS nanoparticles with cubic and hexagonal structure. It was observed that the presence of Sn does not alter the structure of CdZnS. Average crystallite size was measured from XRD data by using Scherrer’s formula. From the study of absorption spectra, band-to-band absorption was obtained at 460 and 490 nm, respectively, for the Sn-doped (2 and 4 mol%) CdZnS nanoparticles. Energy bandgap for undoped and Sn-doped CdZnS varies from 3.5 to 2.9 eV with error ± 0.05 eV. The presence of Sn was confirmed by energy-dispersive X-ray analysis. The effect of dopant concentration on the photoluminescence (PL) intensity has also been studied. The PL emission peak has been observed at 540, 550 and 560 nm for the Sn-doped (CdZnS, CdZnS 2 mol% and CdZnS 4 mol%), respectively, nanoparticles. XRD and PL analyses demonstrate that the Sn2+ ions uniformly substitute Cd2+ sites or interstitial sites in CdZnS lattice, which influence the optical properties. Increase in the concentration of Sn shifts the UV–vis absorption spectra and PL emission spectra towards higher wavelength side. Particle size and the crystallinity of CdZnS : Sn nanoparticles were confirmed through atomic force microscopy.

  9. Pb and Cd on growth, leaf ultrastructure and essential oil yield mint (Mentha arvensis L.

    Directory of Open Access Journals (Sweden)

    Caroline Nery Jezler

    2015-03-01

    Full Text Available Contamination of medicinal plants with heavy metals as Pb and Cd can affect the growth and the essential oil production of the plants and represent a risk to those who consume as medicine. This study aimed to evaluate the effects of absorption and localization of Pb and Cd on growth, ultrastructural aspects of leaves and essential oil yield and composition of Mentha arvensis, applied on the soil with increasing concentrations (8, 16, 32, 64 and 128mg kg-1. There was a differential absorption of Pb and Cd by M. arvensis mainly concentrated in the roots. Pb was found in small amounts in the leaves while Cd largely exceeded the safety limit without symptoms of toxicity. The ultrastructural analysis revealed the metal accumulation on vesicles surrounding the mitochondria and the presence of electron dense deposits surrounding the mitochondria, nucleus and chloroplasts. Little changes caused by Pb and Cd application were not enough to affect the growth and essential oil yield and composition of M. arvensis

  10. An experimental and thermodynamic equilibrium investigation of the Pb, Zn, Cr, Cu, Mn and Ni partitioning during sewage sludge incineration.

    Science.gov (United States)

    Liu, Jingyong; Fu, Jiewen; Ning, Xun'an; Sun, Shuiyu; Wang, Yujie; Xie, Wuming; Huang, Shaosong; Zhong, Sheng

    2015-09-01

    The effects of different chlorides and operational conditions on the distribution and speciation of six heavy metals (Pb, Zn, Cr, Cu, Mn and Ni) during sludge incineration were investigated using a simulated laboratory tubular-furnace reactor. A thermodynamic equilibrium investigation using the FactSage software was performed to compare the experimental results. The results indicate that the volatility of the target metals was enhanced as the chlorine concentration increased. Inorganic-Cl influenced the volatilization of heavy metals in the order of Pb>Zn>Cr>Cu>Mn>Ni. However, the effects of organic-Cl on the volatility of Mn, Pb and Cu were greater than the effects on Zn, Cr and Ni. With increasing combustion temperature, the presence of organic-Cl (PVC) and inorganic-Cl (NaCl) improved the transfer of Pb and Zn from bottom ash to fly ash or fuse gas. However, the presence of chloride had no obvious influence on Mn, Cu and Ni. Increased retention time could increase the volatilization rate of heavy metals; however, this effect was insignificant. During the incineration process, Pb readily formed PbSiO4 and remained in the bottom ash. Different Pb compounds, primarily the volatile PbCl2, were found in the gas phase after the addition of NaCl; the dominant Pb compounds in the gas phase after the addition of PVC were PbCl2, Pb(ClO4)2 and PbCl2O4. PMID:26354691

  11. Chelation Ion Chromatography on 1-(2-Pyridylazo-2-naphthol Sorbed Stannic Silicate: Selective Separation of Cd2+, Hg2+ and Pb2+ from some Transition Metal Ions

    Directory of Open Access Journals (Sweden)

    Rawat, J.P.

    2011-12-01

    Full Text Available Selective separation of three of the most toxic metal ions Cd2+, Hg2+ and Pb2+ has been achieved on a column packed with 1-(2-pyridylazo-2-naphthol (PAN sorbed stannic silicate using nitric acid solution of pH 1 and 6 as eluents. Adsorption behavior of several metal ions like Al3+, Cr3+, Mn2+, Fe3+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Hg2+ and Pb2+ on PAN sorbed stannic silicate from aqueous solution at different pH (from 1 to 6 was studied to calculate their distribution coefficients. In addition to the selective separation of Cd2+, Hg2+ and Pb2+ several binary separations of metal ions e. g., Hg2+ - Al3+, Pb2+ - Cr3+, Cd2+ - Cr3+ and Hg2+ - Cr3+ using aqueous solutions of pH 6 and pH 1 aseluents have been successfully achieved on PAN sorbed stannic silicate.

  12. The Changes of Elements Composition in Aspergillus niger and Aspergillus terreus at Different Co2+, Cd2+ and Pb2+ Concentrations Using X-rays Microanalysis

    International Nuclear Information System (INIS)

    X-ray microanalysis in electron microscope allows simultaneous detection and quantitative analysis of several elements so it contributes to understand the role of ions in physiological processes. Energy dispersive X-ray (EDX) analysis used to detect the changes in elements levels in Aspergillus niger and Aspergillus terreus when allowing to grow on Czapek's Dox liquid media amended with different Co2+, Cd2+ and Pb2+ concentrations and these changes may play a role in fungal uptake for these heavy metal ions. Results showed that Ca, Zn and Cu levels in both fungal isolates significantly decreased (P<0.05) when concentrations of used metal ions increased, also O, Na, Cl and K levels for A. niger and C and P for A. terreus recorded significant reduction (P<0.05) in their percentages. Also, the results revealed that, C and P for A. niger and O, Na, Mg, Cl and K levels for A. terreus significantly increased (P<0.05) as a result of increasing metal ions concentrations. Lack of Cd and Pb peaks in X-ray spectrum for A. terreus led this work to conclude that, A. niger was more effective than A. terreus in Co, Cd, Pb uptake into fungal biomass. The increase or decrease of levels of detected elements could be related to the difference between two fungal isolates in uptake certain heavy metal ion (Co, Cd, Pb)

  13. Study on structure and properties of CuZn40Pb alloy

    Science.gov (United States)

    Achiţei, D. C.; Minciună, M. G.; Vizureanu, P.; Sandu, A. V.; Cimpoeşu, R.; Istrate, B.

    2016-06-01

    The paper shows aspects about the behavior of Cu-Zn-Pb alloys a subjected to the temperatures variation and corrosion resistance in saline medium (sea water). The chemical composition was determined by spectral analysis on optical spectrometer, type Foundry Masters. The experiments are completed by a microstructure analysis made on scanning electronic microscope.

  14. Thermal analysis and prediction of phase equilibria in ternary Pb-Zn-Ag System

    Czech Academy of Sciences Publication Activity Database

    Živković, D.; Minić, D.; Manasijević, D.; Šesták, Jaroslav; Živković, Ž.

    2011-01-01

    Roč. 47, č. 1 (2011), 23-30. ISSN 1450-5339 Institutional research plan: CEZ:AV0Z10100521 Keywords : Pb-Zn-Ag system * thermal analysis * phase equilibrium Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.317, year: 2011

  15. Mathematical interpretation of kinetics of the Zletovo mine rougher Pb - Zn flotation

    OpenAIRE

    Golomeov, Blagoj; Krstev, Boris; Golomeova, Mirjana

    2001-01-01

    Several equations that describe the kinetics of the flotation process can be found in literature regarding flotation concentration. One of the most appropriate, no doubt, is Agar’s equation. This paper make an attempt to describe the kinetics of rougher Pb - Zn flotation process in the Zletovo mine using this equation.

  16. Interdiffusion of CdS and Zn2SnO4 layers and its application in CdS/CdTe polycrystalline thin-film solar cells

    International Nuclear Information System (INIS)

    In this work, we found that the interdiffusion of the CdS and Zn2SnO4 (ZTO) layers can occur either at high temperature (550--650oC) in Ar or at lower temperature (400--420oC) in a CdCl2 atmosphere. By integrating a Zn2SnO4 film into a CdS/CdTe solar cell as a buffer layer, this interdiffusion feature can solve several critical issues and improve device performance and reproducibility of both SnO2-based and Cd2SnO4-based CdTe cells. Interdiffusion consumes the CdS film from both the ZTO and CdTe sides during the device fabrication process and improves quantum efficiency at short wavelengths. The ZTO film acts as a Zn source to alloy with the CdS film, which results in increases in the band gap of the window layer and in short-circuit current density Jsc. Interdiffusion can also significantly improve device adhesion after CdCl2 treatment, thus providing much greater process latitude when optimizing the CdCl2 process step. The optimum CdCl2-treated CdTe device has high quantum efficiency at long wavelength, because of its good junction properties and well-passivated CdTe film. We have fabricated a Cd2SnO4/Zn2SnO4/CdS/CdTe cell demonstrating an NREL-confirmed total-area efficiency of 15.8% (Voc=844.3mV, Jsc=25.00mA/cm2, and fill factor=74.82%). This high-performance cell is one of the best thin-film CdTe solar cells in the world

  17. Interdiffusion of CdS and Zn2SnO4 layers and its application in CdS/CdTe polycrystalline thin-film solar cells

    Science.gov (United States)

    Wu, X.; Asher, S.; Levi, D. H.; King, D. E.; Yan, Y.; Gessert, T. A.; Sheldon, P.

    2001-04-01

    In this work, we found that the interdiffusion of the CdS and Zn2SnO4 (ZTO) layers can occur either at high temperature (550-650 °C) in Ar or at lower temperature (400-420 °C) in a CdCl2 atmosphere. By integrating a Zn2SnO4 film into a CdS/CdTe solar cell as a buffer layer, this interdiffusion feature can solve several critical issues and improve device performance and reproducibility of both SnO2-based and Cd2SnO4-based CdTe cells. Interdiffusion consumes the CdS film from both the ZTO and CdTe sides during the device fabrication process and improves quantum efficiency at short wavelengths. The ZTO film acts as a Zn source to alloy with the CdS film, which results in increases in the band gap of the window layer and in short-circuit current density Jsc. Interdiffusion can also significantly improve device adhesion after CdCl2 treatment, thus providing much greater process latitude when optimizing the CdCl2 process step. The optimum CdCl2-treated CdTe device has high quantum efficiency at long wavelength, because of its good junction properties and well-passivated CdTe film. We have fabricated a Cd2SnO4/Zn2SnO4/CdS/CdTe cell demonstrating an NREL-confirmed total-area efficiency of 15.8% (Voc=844.3 mV, Jsc=25.00 mA/cm2, and fill factor=74.82%). This high-performance cell is one of the best thin-film CdTe solar cells in the world.

  18. Influence of Zn and Pb on Rhizopogon roseolus mycelium - energy dispersion spectroscopy and cytochemical investigation

    Directory of Open Access Journals (Sweden)

    Katarzyna Turnau

    2014-02-01

    Full Text Available Mycelium isolated from fruitbodies of Rhizopogon roseolus, collected from calamine wastes in Poland, was cultivated on agar media supplemented with Zn or Pb salts. The stimulation of exudate production by the aerial mycelium and the mycelium growing on the surface of the media, accompanied by the change of mycelium pigmentation, was found as a result of Zn application. The presence of Pb resulted mainly in the stimulation of crystalloid production on the surface of mycelium, in direct contact with the medium. Exudate droplets formed on the surface of mycelium cultivated on media with and without the Zn addition, were investigated by means of cytochemical tests (PATAg and Gomori-Swift reaction. In the control media most droplets gave a diffused, positive reaction to both tests. In media supplemented with Zn salts, besides the droplet-like material described in the control also another kind of exudate was observed. It was characterized by the collar showing apositive Gomori-Swift reaction, while the rest of the exudate had an oily appearance and gave a faint or no reaction to both tests. Comparative research by means of scanning electron microscopy accompanied by energy dispersion spectroscopy, was carried out showing the differences in exudate and in mycelia composition as a result of the Zn and Pb presence in the medium.

  19. Tandem Quadruplication of HMA4 in the Zinc (Zn) and Cadmium (Cd) Hyperaccumulator Noccaea caerulescens

    OpenAIRE

    Seosamh Ó Lochlainn; Helen C Bowen; Fray, Rupert G.; Hammond, John P.; King, Graham J.; White, Philip J.; Graham, Neil S; Martin R Broadley

    2011-01-01

    Zinc (Zn) and cadmium (Cd) hyperaccumulation may have evolved twice in the Brassicaceae, in Arabidopsis halleri and in the Noccaea genus. Tandem gene duplication and deregulated expression of the Zn transporter, HMA4, has previously been linked to Zn/Cd hyperaccumulation in A. halleri. Here, we tested the hypothesis that tandem duplication and deregulation of HMA4 expression also occurs in Noccaea. A Noccaea caerulescens genomic library was generated, containing 36,864 fosmid pCC1FOS™ clones ...

  20. Comparison of essential and non-essential element distribution in leaves of the Cd/Zn hyperaccumulator Thlaspi praecox as revealed by micro-PIXE.

    Science.gov (United States)

    Vogel-Mikus, Katarina; Simcic, Jure; Pelicon, Primoz; Budnar, Milos; Kump, Peter; Necemer, Marijan; Mesjasz-Przybyłowicz, Jolanta; Przybyłowicz, Wojciech J; Regvar, Marjana

    2008-10-01

    A detailed localization of elements in leaf tissues of the field-collected Cd/Zn hyperaccumulator Thlaspi praecox (Brassicaceae) growing at a highly metal-polluted site was determined by micro-proton-induced X-ray emission (micro-PIXE) in order to reveal and compare nutrient and non-essential element accumulation patterns in the case of multiple metal accumulation within particular leaf tissues, including the detailed distribution between apoplast and symplast regions. On the larger scans, the highest concentrations of metals were observed in the epidermis, S and Ca in the palisade mesophyll, Cl in the spongy mesophyll and vascular bundles, and P and K in the vascular bundles. On the more detailed scans, the highest Cd, Pb, Cl and K concentrations were observed in vascular bundle collenchyma. The relative element distribution (%) was calculated based on concentrations of elements in particular leaf tissues and their relative weight portions, indicating that most of the accumulated Zn was located in epidermises, while the majority of Cd and Pb was distributed within the mesophyll. Detailed scans of epidermal/mesophyll tissues revealed that Zn was mainly accumulated and detoxified in the symplast of large vacuolated epidermal cells, Cd in the mesophyll symplast, and Pb in the mesophyll symplast and apoplast. PMID:18643900

  1. Telescopium telescopium as potential biomonitors of Cu, Zn, and Pb for the tropical intertidal area.

    Science.gov (United States)

    Yap, C K; Noorhaidah, A; Azlan, A; Nor Azwady, A A; Ismail, A; Ismail, A R; Siraj, S S; Tan, S G

    2009-02-01

    The distributions of Cu, Zn, and Pb concentrations in the selected soft tissues (foot, cephalic tentacle, mantle, muscle, gill, digestive caecum, and remaining soft tissues) and shells of the mud-flat snail Telescopium telescopium were determined in snails from eight geographical sites in the south-western intertidal area of Peninsular Malaysia. Generally, the digestive caecum compared with other selected soft tissues, accumulated higher concentration of Zn (214.35+/-14.56 microg/g dry weight), indicating that the digestive caecum has higher affinity for the essential Zn to bind to metallothionein. The shell demonstrated higher concentrations of Pb (41.23+/-1.20 microg/g dry weight) when compared to the selected soft tissues except gill from Kuala Sg. Ayam (95.76+/-5.32 microg/g dry weight). The use of different soft tissues also can solve the problem of defecation to reduce error in interpreting the bioavailability of heavy metals in the intertidal area. PMID:18243309

  2. Optical properties of thermally annealed CdZnSe/ZnSe quantum dots

    International Nuclear Information System (INIS)

    To analyse the diffusion characteristics, photoluminescence (PL) spectroscopy has been carried out in extensive detail on single, as well as, ensembles of thermally annealed (TA) CdSe/ZnSe QDs. For a series of QD-ensembles, each annealed for tA = 30 s at temperatures from TA = 300-550 C, the change in the QD-composition has been calculated from the blue-shift of the exciton ground-state PL-emission, using a concentration function based on Fick's laws of diffusion. The diffusion length (LD) and the activation energy (EA) have been determined thereof. For the studied QDs, EA has been evaluated to be 2.2 eV. Additionally, TA results also in an enhancement of the PL-intensity and reduction of the full-width-at-half maximum (FWHM) of the spectra. This point towards an increased homogeneity of the QD-size and composition, and decrease in the concentration of defects around the QDs. For single CdSe/ZnSe QDs, TA has been varied from 100-240 C, in steps for 20 C, with tA kept fixed at 30 s. Finally, the evolution of the magneto-optic response with post-growth thermal annealing has been studied for both individual QDs and QD-ensembles. An external magnetic field, applied perpendicular to the plane of the QDs (Faraday configuration), results in Zeeman spin splitting of the ground exciton state. The emissions from the Zeeman-split states are left and right circularly polarized and from the degree of circular polarization (DCP), as well as, the spectral separation of the PL-peaks, the g-factor can be estimated. For CdSe/ZnSe QD-ensembles, the g-factor has been observed to change sign with TA. (orig.).

  3. Carbonate-hosted nonsulphide Zn-Pb mineralization of southern British Columbia, Canada

    Science.gov (United States)

    Paradis, Suzanne; Keevil, Halley; Simandl, George J.; Raudsepp, Mati

    2015-12-01

    Many carbonate-hosted sulphide deposits in the Salmo district of southern British Columbia have near-surface Zn- and Pb-bearing iron oxide-rich gossans. The gossans formed when carbonate-hosted, base metal sulphides were subjected to intense supergene weathering processes and metals were liberated by the oxidation of sulphide minerals. Two types of supergene carbonate-hosted nonsulphide deposits, direct replacement (`red ore') and wallrock replacement (`white ore'), are present in the Salmo district. The direct replacement deposits formed by the oxidation of primary sulphides; the base metals passed into solution and were redistributed and trapped within the space occupied by the oxidized portion of the sulphide protore. Depending on the extent of replacement of the sulphides by Zn-, Pb- and Fe-bearing oxides, silicates, carbonates and phosphates, the resulting ore can be called `mixed' (sulphides and nonsulphides) or simply `nonsulphide'. The wallrock replacement deposits formed when base metals liberated by the oxidation of sulphides were transported by circulating supergene solutions down and/or away from the sulphides to form wallrock replacement deposits. The direct replacement nonsulphide zones of the Salmo district overlay the sulphide bodies in which they replaced the sulphides and carbonates, forming large irregular replacement masses, encrustations and open-space fillings. They consist predominantly of hematite, goethite, hemimorphite [Zn4Si2O7(OH)2·H2O], minor hydrozincite [Zn5(CO3)2(OH)6], cerussite [PbCO3] and traces of willemite [Zn2SiO4]. The wallrock replacement zones consist mainly of hemimorphite with local occurrences of iron oxides, hopeite [Zn3(PO4)2·4H2O] and tarbuttite [Zn2(PO4)(OH)]. No remnants of sulphides were observed in the replacement zones. The Salmo nonsulphide deposits were formed by prolonged weathering of Mississippi Valley-type (MVT) mineralization that underwent dissolution and oxidation of the pyrite, sphalerite and galena

  4. Thallium transformation and partitioning during Pb-Zn smelting and environmental implications.

    Science.gov (United States)

    Liu, Juan; Wang, Jin; Chen, Yongheng; Xie, Xiaofan; Qi, Jianying; Lippold, Holger; Luo, Dinggui; Wang, Chunlin; Su, Longxiao; He, Lucheng; Wu, Qiwei

    2016-05-01

    Thallium (Tl) is a toxic and non-essential heavy metal. Raw Pb-Zn ores and solid smelting wastes from a large Pb-Zn smelting plant - a typical thallium (Tl) pollution source in South China, were investigated in terms of Tl distribution and fractionation. A modified IRMM (Institute for Reference Materials and Measurement, Europe) sequential extraction scheme was applied on the samples, in order to uncover the geochemical behavior and transformation of Tl during Pb-Zn smelting and to assess the potential environmental risk of Tl arising from this plant. Results showed that the Pb-Zn ore materials were relatively enriched with Tl (15.1-87.7 mg kg(-1)), while even higher accumulation existed in the electrostatic dust (3280-4050 mg kg(-1)) and acidic waste (13,300 mg kg(-1)). A comparison of Tl concentration and fraction distribution in different samples clearly demonstrated the significant role of the ore roasting in Tl transformation and mobilization, probably as a result of alteration/decomposition of related minerals followed by Tl release and subsequent deposition/co-precipitation on fine surface particles of the electrostatic dust and acidic waste. While only 10-30% of total Tl amounts was associated with the exchangeable/acid-extractable fraction of the Pb-Zn ore materials, up to 90% of total Tl was found in this fraction of the electrostatic dust and acidic waste. Taking into account the mobility and bioavailability of this fraction, these waste forms may pose significant environmental risk. PMID:26840520

  5. Total reflection X-ray fluorescence and energy-dispersive X-ray fluorescence analysis of runoff water and vegetation from abandoned mining of Pb-Zn ores

    International Nuclear Information System (INIS)

    The present work reports on the heavy metal content: Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Cd and Pb in running waters and vegetation around abandoned mining areas. Two species of mosses (Dicranum sp. and Pleurocarpus sp.) and three different species of wild grass (Bromus sp., Rumex sp. and Pseudoavena sp.) growing on the surrounding areas of old lead-zinc mines (Aran Valley, Pyrenees, NE Spain) have been analyzed. Both water and vegetation were collected in two different sampling places: (a) near the mine gallery water outlets and (b) on the landfill close to the abandoned mineral concentration factories. For the heavy metal content determination, two different techniques were used: total reflection X-ray fluorescence for water analysis and energy-dispersive X-ray fluorescence for vegetation study. Surface waters around mine outlets exhibit anomalous content of Co, Ni, Zn, Cd. Stream waters running on mining landfills exhibit higher Cu, Zn, Cd and Pb than those of the waters at the mine gallery outlets. The results allow us to assess the extent of the environmental impact of the mining activities on the water quality. The intake of these elements by vegetation was related with the sampling place, reflecting the metal water content and the substrate chemistry. Accumulation of metals in mosses is higher than those exhibited in wild grasses. Furthermore, different levels of accumulation were found in different wild grass. Rumex sp. presented the lowest metal concentrations, while Pseudoavena sp. reported the highest metal content

  6. Total reflection X-ray fluorescence and energy-dispersive X-ray fluorescence analysis of runoff water and vegetation from abandoned mining of Pb Zn ores

    Science.gov (United States)

    Marques, A. F.; Queralt, I.; Carvalho, M. L.; Bordalo, M.

    2003-12-01

    The present work reports on the heavy metal content: Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Cd and Pb in running waters and vegetation around abandoned mining areas. Two species of mosses ( Dicranum sp. and Pleurocarpus sp.) and three different species of wild grass ( Bromus sp., Rumex sp. and Pseudoavena sp.) growing on the surrounding areas of old lead-zinc mines (Aran Valley, Pyrenees, NE Spain) have been analyzed. Both water and vegetation were collected in two different sampling places: (a) near the mine gallery water outlets and (b) on the landfill close to the abandoned mineral concentration factories. For the heavy metal content determination, two different techniques were used: total reflection X-ray fluorescence for water analysis and energy-dispersive X-ray fluorescence for vegetation study. Surface waters around mine outlets exhibit anomalous content of Co, Ni, Zn, Cd. Stream waters running on mining landfills exhibit higher Cu, Zn, Cd and Pb than those of the waters at the mine gallery outlets. The results allow us to assess the extent of the environmental impact of the mining activities on the water quality. The intake of these elements by vegetation was related with the sampling place, reflecting the metal water content and the substrate chemistry. Accumulation of metals in mosses is higher than those exhibited in wild grasses. Furthermore, different levels of accumulation were found in different wild grass. Rumex sp. presented the lowest metal concentrations, while Pseudoavena sp. reported the highest metal content.

  7. Chalcophile elements Hg, Cd, Pb, As in Lake Umbozero, Murmansk Region, Russia

    DEFF Research Database (Denmark)

    Dauvalter, V.A.; Kashulin, N.A.; Lehto, J.; Jernström, Jussi

    2009-01-01

    affected by emissions and effluents from mining and metallurgical enterprises of the Murmansk Region, as well as air pollution of a global character. Surface and near-bottom maxima were found in the distributions of Pb and Cd in the water column. These two maxima appear to be associated with the cyclical...... growth of phytoplankton in surface water layers and with sedimentation of lifeless organisms and suspended particles in near-bottom layers. Average concentrations of Pb and Cd in the water column were more than the average value for water of lakes of the taiga zone. Pollution of Lake Umbozero led to......Investigations of Lake Umbozero, the second largest and the deepest lake of the Murmansk Region, were carried out to detect and define biogeochemical patterns of distribution of the chalcophile elements (Hg, Cd, Pb, As) in water, sediments and organs and tissues of whitefishes. Lake Umbozero is...

  8. Chalcophile elements Hg, Cd, Pb, As in Lake Umbozero, Murmansk Region, Russia

    DEFF Research Database (Denmark)

    Dauvalter, V.A.; Kashulin, N.A.; Lehto, J.;

    2009-01-01

    is affected by emissions and effluents from mining and metallurgical enterprises of the Murmansk Region, as well as air pollution of a global character. Surface and near-bottom maxima were found in the distributions of Pb and Cd in the water column. These two maxima appear to be associated with the cyclical...... growth of phytoplankton in surface water layers and with sedimentation of lifeless organisms and suspended particles in near-bottom layers. Average concentrations of Pb and Cd in the water column were more than the average value for water of lakes of the taiga zone. Pollution of Lake Umbozero led......Investigations of Lake Umbozero, the second largest and the deepest lake of the Murmansk Region, were carried out to detect and define biogeochemical patterns of distribution of the chalcophile elements (Hg, Cd, Pb, As) in water, sediments and organs and tissues of whitefishes. Lake Umbozero...

  9. Water-soluble CdSe/CdS and CdSe/Cd{sub x}Zn{sub 1-x}S quantum dots with tunable and narrow luminescent spectra and high photoluminescence efficiency

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Qiang; Cao, Yongqiang [University of Jinan, Shandong Provincial Key Laboratory of Preparation and Measurement of Building Materials, Key Laboratory of Inorganic Functional Materials of Shandong Universities, School of Material Science and Engineering (China); Shen, Jianxing [Shandong Polytechnic University, Key Laboratory of Processing and Testing Technology of Glass and Functional Ceramics of Shandong Province, Department of Materials Science and Engineering (China); Yang, Ping, E-mail: mse_yangp@ujn.edu.cn [University of Jinan, Shandong Provincial Key Laboratory of Preparation and Measurement of Building Materials, Key Laboratory of Inorganic Functional Materials of Shandong Universities, School of Material Science and Engineering (China)

    2013-08-15

    Nearly monodisperse CdSe/CdS and CdSe/Cd{sub x}Zn{sub 1-x}S core-shell quantum dots (QDs) were synthesized by the epitaxial growth of CdS or Cd{sub x}Zn{sub 1-x}S shells on pre-synthesized CdSe cores through a facile organic route. The thickness effect of CdS and Cd{sub x}Zn{sub 1-x}S shells on the properties of resulting core-shell QDs, such as the photoluminescence (PL) efficiency, PL full width at half-maximum (fwhm), and PL decay lifetime, were investigated. The PL efficiency is greatly enhanced from 9 % of CdSe cores to 64 % of CdSe/Cd{sub x}Zn{sub 1-x}S core-shell QDs. The PL spectra are narrowed after coating (fwhm {approx}28-32 nm). The alloy Cd{sub x}Zn{sub 1-x}S shell is especially effective to enhance the PL efficiency, and it leads to a smaller red-shift in PL spectra compared with that of the CdS shell. The water-soluble CdSe/Cd{sub x}Zn{sub 1-x}S core-shell QDs were obtained by the encapsulation of amphiphilic poly(styrene-co-maleic anhydride) (PSMA)-ethanolamine (EA) polymers, which was initially dispersed in oil phase. It was found that the CdSe/Cd{sub x}Zn{sub 1-x}S QDs in water still retained a high PL efficiency as well as a small value in fwhm after encapsulating the CdSe/Cd{sub x}Zn{sub 1-x}S QDs with PSMA-EA polymers, expanding the applications of these core-shell QDs in aqueous environment.

  10. Lanthanide modification of CdSe/ZnS core/shell quantum dots

    DEFF Research Database (Denmark)

    Dethlefsen, Johannes Rytter; Mikhailovsky, Alexander A.; Burks, Peter T.;

    2012-01-01

    Lanthanide-modified CdSe quantum dots (CdSe(Ln) QDs) have been prepared by heating a solution of Cd(oleate)(2), SeO2, and Ln(bipy)(S2CNEt2)(3) (bipy = 2,2'-bipyridine) to 180-190 degrees C for 10-15 min. The elemental compositions of the resulting CdSe(Ln) cores and CdSe(Ln)/ZnS core/shell QDs show...

  11. Graded-Bandgap Solar Cells Using All-Electrodeposited ZnS, CdS and CdTe Thin-Films

    OpenAIRE

    Obi K. Echendu; Imyhamy M. Dharmadasa

    2015-01-01

    A 3-layer graded-bandgap solar cell with glass/FTO/ZnS/CdS/CdTe/Au structure has been fabricated using all-electrodeposited ZnS, CdS and CdTe thin layers. The three semiconductor layers were electrodeposited using a two-electrode system for process simplification. The incorporation of a wide bandgap amorphous ZnS as a buffer/window layer to form glass/FTO/ZnS/CdS/CdTe/Au solar cell resulted in the formation of this 3-layer graded-bandgap device structure. This has yielded corresponding impro...

  12. High voltage optimization in CdZnTe detectors

    Energy Technology Data Exchange (ETDEWEB)

    Awadalla, S.A., E-mail: salahawadalla@yahoo.com [College of Engineering, Taibah University, Yanbu (Saudi Arabia); Al-Grafi, M. [College of Engineering, Taibah University, Yanbu (Saudi Arabia); Iniewski, K. [Redlen Technologies, Victoria BC (Canada)

    2014-11-11

    The focus of this paper is to investigate, experimentally and theoretical, the optimum operating bias, in cadmium zinc telluride Cd {sub 0.9}Zn{sub 0.1}Te (CZT) crystals grown using the traveling heater method (THM), required to achieve maximum energy resolution. It was found that 5 mm thick detectors that have low electron trapping, (μτ)e≥1×10{sup −2} cm{sup 2}/V, operates efficiently at relatively low applied bias, 200 V; while detectors with high electron trapping, (μτ)e≤5×10{sup −3} cm{sup 2}/V, required relative high voltage: as high as 1000 V for 5 mm thick detectors. Similarly 10 mm thick detectors can be operated at as low as 500 V. Moreover, both charge collection efficiency (CCE) and energy resolution(ER) were found to follow the same trend.

  13. Multichannel CdZnTe gamma ray spectrometer

    Science.gov (United States)

    Doty, F. P.; Lingren, C. L.; Apotovsky, B. A.; Brunsch, J.; Butler, J. F.; Collins, T.; Conwell, R. L.; Friesenhahn, S.; Gormley, J.; Pi, B.; Zhao, S.; Augustine, F. L.; Bennett, B. A.; Cross, E.; James, R. B.

    1999-02-01

    A 3 cm 3 multichannel gamma spectrometer for DOE applications is under development by Digirad Corporation. The device is based on a position sensitive detector packaged in a compact multi-chip module (MCM) with integrated readout circuitry. The modular, multichannel design will enable identification and quantitative analysis of radionuclides in extended sources, or sources containing low levels of activity. The MCM approach has the advantages that the modules are designed for imaging applications, and the sensitivity can be arbitrarily increased by increasing the number of pixels, i.e. adding modules to the instrument. For a high sensitivity probe, the outputs for each pixel can be corrected for gain and offset variations, and summed digitally. Single pixel results obtained with discrete low noise readout indicate energy resolution of 3 keV can be approached with currently available CdZnTe. The energy resolution demonstrated to date with MCMs for 511 keV gamma rays is 10 keV.

  14. High voltage optimization in CdZnTe detectors

    International Nuclear Information System (INIS)

    The focus of this paper is to investigate, experimentally and theoretical, the optimum operating bias, in cadmium zinc telluride Cd 0.9Zn0.1Te (CZT) crystals grown using the traveling heater method (THM), required to achieve maximum energy resolution. It was found that 5 mm thick detectors that have low electron trapping, (μτ)e≥1×10−2 cm2/V, operates efficiently at relatively low applied bias, 200 V; while detectors with high electron trapping, (μτ)e≤5×10−3 cm2/V, required relative high voltage: as high as 1000 V for 5 mm thick detectors. Similarly 10 mm thick detectors can be operated at as low as 500 V. Moreover, both charge collection efficiency (CCE) and energy resolution(ER) were found to follow the same trend

  15. Modelling the leaching of Pb, Cd, As, and Cr from cementitious waste using PHREEQC

    International Nuclear Information System (INIS)

    A leaching model was developed using the United States Geological Survey public domain PHREEQC geochemical package to simulate the leaching of Pb, Cd, As, and Cr from cementitious wastes. The model utilises both kinetic terms and equilibrium thermodynamics of key compounds and provides information on leachate and precipitate speciation. The model was able to predict the leaching of Pb, Cd, As, and Cr from cement in the presence of both simple (0.1 and 0.6 M acetic acid) and complex municipal landfill leachates. Heavy metal complexation by the municipal landfill leachate was accounted for by the introduction of a monoprotic organic species into the model. The model indicated Pb and As were predominantly incorporated within the calcium silicate hydrate matrix while a greater portion of Cd was seen to exist as discrete particles in the cement pores and Cr (VI) existed mostly as free CrO42- ions. Precipitation was found to be the dominant mechanism controlling heavy metal solubility with carbonate and silicate species governing the solubility of Pb and carbonate, silicate and hydroxide species governing the solubility of Cd. In the presence of acetic acid, at low pH values Pb and Cd acetate complexes were predominant whereas, at high pH values, hydroxide species dominated. At high pH values, the concentration of As in the leachate was governed by the solubility of Ca3(AsO4)2 with the presence of carbonate alkalinity competing with arsenate for Ca ions. In the presence of municipal landfill leachate, Pb and Cd organic complexes dominated the heavy metal species in solution. The reduction of As and Cr in municipal landfill leachate was crucial for determining aqueous speciation, with typical municipal landfill conditions providing the reduced forms of As and Cr

  16. Modelling the leaching of Pb, Cd, As, and Cr from cementitious waste using PHREEQC.

    Science.gov (United States)

    Halim, Cheryl E; Short, Stephen A; Scott, Jason A; Amal, Rose; Low, Gary

    2005-10-17

    A leaching model was developed using the United States Geological Survey public domain PHREEQC geochemical package to simulate the leaching of Pb, Cd, As, and Cr from cementitious wastes. The model utilises both kinetic terms and equilibrium thermodynamics of key compounds and provides information on leachate and precipitate speciation. The model was able to predict the leaching of Pb, Cd, As, and Cr from cement in the presence of both simple (0.1 and 0.6M acetic acid) and complex municipal landfill leachates. Heavy metal complexation by the municipal landfill leachate was accounted for by the introduction of a monoprotic organic species into the model. The model indicated Pb and As were predominantly incorporated within the calcium silicate hydrate matrix while a greater portion of Cd was seen to exist as discrete particles in the cement pores and Cr (VI) existed mostly as free CrO4(2-) ions. Precipitation was found to be the dominant mechanism controlling heavy metal solubility with carbonate and silicate species governing the solubility of Pb and carbonate, silicate and hydroxide species governing the solubility of Cd. In the presence of acetic acid, at low pH values Pb and Cd acetate complexes were predominant whereas, at high pH values, hydroxide species dominated. At high pH values, the concentration of As in the leachate was governed by the solubility of Ca3(AsO4)2 with the presence of carbonate alkalinity competing with arsenate for Ca ions. In the presence of municipal landfill leachate, Pb and Cd organic complexes dominated the heavy metal species in solution. The reduction of As and Cr in municipal landfill leachate was crucial for determining aqueous speciation, with typical municipal landfill conditions providing the reduced forms of As and Cr. PMID:16043281

  17. CdSe 与 CdSe/ZnS 量子点合成及稀土掺杂%Synthesis and rare earth doped of CdSe and CdSe/ZnS QDs

    Institute of Scientific and Technical Information of China (English)

    薛霏; 孟宪权; 刘义鹤

    2014-01-01

    CdSe,CdSe/ZnS and Eu doped QDs were synthesized in LSS system.The QDs were characterized by TEM,XRD,PL and EDS.The TEM results showed that the QDs had uniform size and morphology.And the results of XRD showed CdSe/ZnS QDs belonged to hexagonal crystal system.The PL of the samples proved that the CdSe QDs coated with suitable thickness ZnS had a remarkable rise in luminous efficiency and the FWHM (the full width half maximum).And we analyzed this results.The CdSe QDs doped with Eu had a new emission peak in red area,while the CdSe(Eu)/ZnS QDs did not.We also clarified the causes of this phenome-non .%在 LSS(liquid-solid-solution)多相体系中制得了 CdSe、CdSe/ZnS 量子点和 Eu 掺杂的量子点.利用 TEM、XRD、PL、EDS 对产物进行了表征.TEM 结果显示所得的量子点形貌规则、尺寸均匀.XRD 结果显示 CdSe/ZnS 量子点呈六方晶系.PL 结果对比表明,合适厚度壳层 ZnS 包覆后的 CdSe 量子点发光效率明显提高,发光峰的半高宽有大幅度提高,并分析了所得的结果.掺杂稀土元素 Eu 后,CdSe(Eu)量子点在红光区域产生了新的发光峰;而 CdSe(Eu)/ZnS 量子点在红光区域内没有出现发光峰,并阐明了这种现象的原因.

  18. Interation of Pb and Cd in Soil—Water—Plant System and Its Mechanism:I.Pb—Cd Interatction in Red SoilPlant System

    Institute of Scientific and Technical Information of China (English)

    ZHENGCHUNRONG; CHENHUAIMAN

    1996-01-01

    A study on the effect of Pb-Cd interaction on plant growth and on the chemistry of elements in plants was conducted under greenhouse condition with red soil-wetland rice system in different growth stage.The results showed that Pb-Cd interactions on growth and metal uptake varied with different growth stages and chemical compounds added .The plant height and the root weght were markedly affected by Pb-Cd interication in the young stage but not in the ripening stage of rice at the treatments of PbCl2 and CdCl2 added.However,the weight of rice straw in the ripening stage was significantly affected by Pb-Cd interaction with the treatments of Pb(OAc)2 and CdCl2.The chemistry of elements in plants also depended on Pb-Cd interaction in varying degrees on account of different plant parts and growth stage.It seems that Pb-Cd interaction occurred not only in roots but also in other parts of wetland rice.

  19. Coordination geometries of Zn(II) and Cd(II) in phosphotriesterase: Influence of water molecules in the active site

    DEFF Research Database (Denmark)

    Krauss, M; Olsen, Lars; Antony, J;

    2002-01-01

    Models of the metal ion binding sites of native ZnZn and of cadmium-substituted ZnCd and CdCd phosphotriesterase, including full amino acid side chains, were geometry optimized with quantum mechanical methods, with effective fragment potentials (EFP) representing the protein environment surroundi...

  20. Study of a new architecture of gamma cameras with Cd/ZnTe/CdTe semiconductors

    International Nuclear Information System (INIS)

    This thesis studies new semi conductors for gammas cameras in order to improve the quality of image in nuclear medicine. The chapter 1 reminds the general principle of the imaging gamma, by describing the radiotracers, the channel of detection and the types of Anger gamma cameras acquisition. The physiological, physical and technological limits of the camera are then highlighted, to better identify the needs of future gamma cameras. The chapter 2 is dedicated to a bibliographical study. At first, semi-conductors used in imaging gamma are presented, and more particularly semi-conductors CDTE and CdZnTe, by distinguishing planar detectors and monolithic pixelated detectors. Secondly, the classic collimators of the gamma cameras, used in clinical routine for the most part of between them, are described. Their geometry is presented, as well as their characteristics, their advantages and their inconveniences. The chapter 3 is dedicated to a state of art of the simulation codes dedicated to the medical imaging and the methods of reconstruction in imaging gamma. These states of art allow to introduce the software of simulation and the methods of reconstruction used within the framework of this thesis. The chapter 4 presents the new architecture of gamma camera proposed during this work of thesis. It is structured in three parts. The first part justifies the use of semiconducting detectors CdZnTe, in particular the monolithic pixelated detectors, by bringing to light their advantages with regard to the detection modules based on scintillator. The second part presents gamma cameras to base of detectors CdZnTe (prototypes or commercial products) and their associated collimators, as well as the interest of an association of detectors CdZnTe in the classic collimators. Finally, the third part presents in detail the HiSens architecture. The chapter 5 describes both software of simulation used within the framework of this thesis to estimate the performances of the Hi

  1. [The impact of ZnS/CdS composite window layer on the quantun efficiency of CdTe solar cell in short wavelength].

    Science.gov (United States)

    Zhang, Li-xiang; Feng, Liang-huan; Wang, Wen-wu; Xu, Hang; Wu, Li-li; Zhang, Jing-quan; Li, Wei; Zeng, Guang-gen

    2015-02-01

    ZnS/CdS composite window layer was prepared by magnetron sputtering method and then applied to CdTe solar cell. The morphology and structure of films were measured. The data of I-V in light and the quantum efficiency of CdTe solar cells with different window layers were also measured. The effect of ZnS films prepared in different conditions on the performance of CdTe solar cells was researched. The effects of both CdS thickness and ZnS/CdS composite layer on the transmission in short wavelength were studied. Particularly, the quantum efficiency of CdTe solar cells with ZnS/CdS window layer was measured. The results show as follows. With the thickness of CdS window layer reducing from 100 to 50 nm, the transmission increase 18.3% averagely in short wavelength and the quantum efficiency of CdTe solar cells increase 27.6% averagely. The grain size of ZnS prepared in 250 degrees C is smaller than prepared at room temperature. The performance of CdTe solar cells with ZnS/CdS window layer is much better if ZnS deposited at 250 degrees C. This indicates grain size has some effect on the electron transportation. When the CdS holds the same thickness, the transmission of ZnS/CdS window layer was improved about 2% in short wavelength compared with CdS window layer. The quantum efficiency of CdTe solar cells with ZnS/CdS window layer was also improved about 2% in short wavelength compared with that based on CdS window layer. These indicate ZnS/CdS composite window layer can increase the photon transmission in short wavelength so that more photons can be absorbed by the absorbent layer of CdTe solar cells. PMID:25970885

  2. Domain structure studies on Pb(Zn1/3Nb2/3)O3-PbTiO3 mixed crystal system

    International Nuclear Information System (INIS)

    In this investigation, ferroelectric Pb(Zn1/3Nb2/3)O3-PbTiO3 single crystals have been grown by modified flux technique with PbO self flux. Well-defined domain patterns were observed through polarized light on the as-grown crystals. Fingerprint like pattern and tweed pattern have also been observed. In PZN-PT system the fingerprint domain area is found to be elongated along one direction for increasing PT content

  3. CdTe,核-壳型CdTe/CdS及CdTe/ZnS量子点的合成及表征%CdTe, Core-shell CdTe/CdS and CdTe/ZnS Quantum Dots: Their Synthesis and Characterization*

    Institute of Scientific and Technical Information of China (English)

    张纪梅; 许世超; 宋秀云; 代昭; 孙波; 姚翠翠

    2009-01-01

    Semiconductor CdTe, core-shell CdTe/CdS and CdTe/ZnS nanocrystals(quantum dots; QDs) were prepared in aqueous phase. Investigations of the prepared nanocrystals were performed via scanning tunneling microscope(STM) and fluorescence spectrum(FS), and quantum yields(Qys) was calculated based on the resulting data from FS. Particle size of well dispersed CdTe was evaluated to be ca 3 nm via STM. Some reaction conditions were investigated and discussed to enhance Qys of CdTe/CdS core-shell QDs, such as dependence of Cd2+ concentration, and effect of Cd2+∶S2- etc. Among all of those methods, Qys of core-shell CdTe/CdS is generally degressive with refluxing time elapsing. The best Qys of ca 80.0% can be achieved when pH was set at 8.5, Cd2+∶S2-=10:1(mol ratio). Moreover, CdTe/ZnS core-shell QDs was prepared, and results indicated a red-shift from 551 nm to 635 nm comparing with CdTe core, which suggested the growth of QDs size, however, Qys of CdTe/ZnS decreased to 14.4%. QDs currently discussed in this research are easily synthesized, and they will be useful in applications of biolabeling, imaging, and biosensing based on fluorescence resonance energy transfer(FRET).%在水相中制备了半导体CdTe纳米晶,核-壳型CdTe/CdS和CdTe/ZnS纳米晶(即量子点;QDs).利用扫描隧道显微镜(STM)和荧光光谱(FS)对合成的纳米晶量子点进行了研究,并且根据FS的数据进行了量子效率的计算.STM的结果表明合成的量子点直径约为3 nm并且分布良好.为了提高量子效率,对Cd2+浓度和Cd2+∶S2-比例等反应条件进行了研究,结果表明随着回流时间的增加,核-壳型量子点CdTe/CdS的量子效率总体上呈下降趋势.CdTe/CdS在pH8.5,Cd2+∶S2-=10∶1(摩尔比)时可获得80.0%的最大量子效率.同时制备了核-壳型量子点CdTe/ZnS,其最大发射波长由551 nm(CdTe)红移到635 nm(CdTe/ZnS)表明量子点的尺寸在增长,但是量子效率下降到14.4%. 当前研究的量子点可适用于生

  4. Structural and electrical measurements of CdZnSe composite

    Indian Academy of Sciences (India)

    V Kishore; Vibhav K Saraswat; N S Saxena; T P Sharma

    2005-08-01

    The – characterization and the electrical resistivity of selenium rich Se85Cd15–Zn ( = 0, 3, 7, 11 and 15) system at room temperature have been studied. Samples were obtained using melt cooling technique. So prepared samples were then characterized in terms of their crystal structure and lattice parameter using X-ray diffraction method. The materials were found to be polycrystalline in nature, having zinc blend structure over the whole range of zinc concentration. The measurements of – characteristics have been carried out at different temperatures from room to 140°C. The electrical resistivity of the samples with composition at room temperature has been found to vary between maximum 2.7 × 108 m and minimum 7.3 × 105 m and shows a maximum at 3 at. wt.% of Zn. The carrier activation energy of the samples with composition has also been determined and found to vary from 0.026 eV to 0.111 eV.

  5. Performance optimization of CdTe and CdZnTe detectors for γ-spectrometry

    International Nuclear Information System (INIS)

    This study deals with room-temperature gamma spectrometry with CdTe and CdZnTe semiconductor detectors. The aim was the improvement of energy resolution and detection efficiency. Some different phenomena have been investigated. Electronic noise knowledge has enabled us to optimize the design of filtering. Charge transport induces signal shape uncertainty and the processing circuit has been adapted in order to account for these variations. Study and simulation of electrical current induction process has permitted the development of a new Frisch-grid based detection structure. We have reached 3% energy resolutions at 122 keV without detection efficiency loss. Finally, the remaining limits of detector performances have been estimated by focusing on gamma interaction phenomena and material non-uniformity problems. (author)

  6. Proton irradiation of MWIR HgCdTe/CdZnTe

    Science.gov (United States)

    Fahey, Stephen; Velicu, Silviu; Bommena, Ramana; Zhao, Jun; Cowan, Vincent; Morath, Christian; Sivananthan, Sivalingam

    2015-09-01

    High performance infrared sensors are vulnerable to slight changes in defect densities and locations. For example in a space application where such sensors are exposed to proton irradiation capable of generating point defects the sensors are known to suffer performance degradation. The degradation can generally be observed in terms of dark current density and responsivity degradations. Here we report results of MWIR HgCdTe/CdZnTe single element diodes dark current densities before and after exposure to 63MeV protons at room temperature to a total ionizing dose of 100 kRad(Si). We find the irradiated diodes as a group show some signs of proton-induced damage in dark current.

  7. Pb and Cd on growth, leaf ultrastructure and essential oil yield mint (Mentha arvensis L.)

    OpenAIRE

    Caroline Nery Jezler; Pedro Antônio Oliveira Mangabeira; Alex-Alan Furtado de Almeida; Raildo Mota de Jesus; Rosilene Aparecida de Oliveira; Delmira da Costa Silva; Larissa Correa do Bomfim Costa

    2015-01-01

    Contamination of medicinal plants with heavy metals as Pb and Cd can affect the growth and the essential oil production of the plants and represent a risk to those who consume as medicine. This study aimed to evaluate the effects of absorption and localization of Pb and Cd on growth, ultrastructural aspects of leaves and essential oil yield and composition of Mentha arvensis, applied on the soil with increasing concentrations (8, 16, 32, 64 and 128mg kg-1). There was a differential absorption...

  8. Low-cost CdZnTe devices for cascade cell application

    Energy Technology Data Exchange (ETDEWEB)

    Basol, B.M.; Kapur, V.K. (International Solar Electric Technology, Inglewood, CA (USA))

    1990-11-01

    This report describes a research program to develop a low-cost technique for producing Cd{sub 1-x}Zn{sub x}Te devices for cascade solar cell applications. The technique involves a two-stage process for fabricating such devices with a band gap of about 1.7 eV and a transparent contact layer of low-resistivity ZnTe. In the first stage, thin films of Cd, Zn, and Te are deposited in stacked layers as Cd{sub 1-x}An{sub x}Te. The second stage involves hearing and reacting the layers to form the compound. At first, electrodeposition was used for depositing the layers to successfully fabricate Dc{sub 1-x}Zn{sub x}Te thin-film devices. These films were also intrinsically doped with copper. For the first time, transparent ZnTe films of low resistivity were obtained in a two-stage process; preliminary solar cells using films with low Zn content were demonstrated. A second phase of the project involved growing films with higher Zn content (>15%). Such films were grown on CdS-coated substrates for fabricating devices. The effects of the solar-cell processing steps on the Cd{sub 1-x}Zn{sub x}Te and CdS/Cd{sub 1-x}Zn{sub x}Te interfaces were studied; results showed that the nature of the interface depended on the stoichiometry of the Cd{sub 1-x}Zn{sub x}Te thin film. A sharp interface was observed for the CdS/CdTe structures, but the interface became highly diffused as the Zn content in the absorber layer increased above 15%. The interaction between the CdS window layer and the Cd{sub 1-x}Zn{sub x}Te absorber layer was found to result from an exchange reaction between Zn in the absorber layer and the thin CdS film. 14 refs., 10 figs.

  9. Mid-infrared active PbTe/CdTe quantum dots: growth, optical properties and device applications

    International Nuclear Information System (INIS)

    with SrTe, allowing a wide wavelength tunability of the emission. The incorporation of Sr also results in a drastic enhancement of the emission intensity, contrary to the strong non-radiative recombination found in bulk ternary alloys. Device applications of PbTe quantum dots as such as light emitting diode and the microdisk laser are presented. Electroluminescence is demonstrated up to room temperature for PbTe dots, embedded in the middle of an n-i-p Cd(Zn)Te junction. Lasing is shown for quantum dots up to 200K in continous wave mode at a wavelenght of 3.8 mym. Using pulsed excitation, the maximum laser operation temperature is raised to 300K. (author)

  10. Growth and characterization of ZnSe/CdSe/ZnSe quantum dots fabricated by using an alternate molecular beam supplying method

    International Nuclear Information System (INIS)

    ZnSe/CdSe/ZnSe structures inserted CdSe thin layer are fabricated using an alternate molecular beam supply (ALS). Examining the PL peak energy dependence on beam irradiation time in ALS cycle, we studied the initial stage of CdSe growth. When CdSe below the critical thickness is supplied on ZnSe grown on GaAs (1 0 0), two kinds of 2D islands (platelets) appear. We confirmed the alloying of 2D-CdSe islands and 3D-CdSe islands (dots) is prominent under Cd beam irradiation in ALS growth

  11. Rujevac Sb-Pb-Zn-As polymetallic deposit, Boranja orefield, Western Serbia: native arsenic and arsenic mineralization

    Science.gov (United States)

    Radosavljević, Slobodan A.; Stojanović, Jovica N.; Radosavljević-Mihajlović, Ana S.; Vuković, Nikola S.

    2014-02-01

    Rujevac is a low-temperature hydrothermal polymetallic Sb-Pb-Zn-As vein-type ore deposit, hosted within a volcanogenic-sedimentary zone situated in the Rujevac-Crvene Stene-Brezovica Diabase-Chert Formation (DCF) of the Podrinje Metallogenic District (PMD), Serbia. It is located several kilometers SE from the Boranja contact aureole, which is an integral part of the PMD in Western Serbia. Genetically related to the Tertiary granodioritic magma, the mineral assemblages are characterized by specific features. The mineral association of this deposit consists of sulfides, Pb-Sb(As) sulfosalts, native metals, oxides, hydroxides and gangue minerals. Chemical composition of the ore is very complex, where contents of valuable metals range as follows: Sb (0.17-24.31 wt.%), Zn (0.21-6.29 wt.%), Pb (0.15-6.33 wt.%), As (0.06-1.28 wt.%), Cd (25-747 ppm), Ag (7-408 ppm), Hg (13-473 ppm), and Tl (<1-29 ppm). Electron Probe Microanalyses (EPMA) of native arsenic from both the Rujevac and Stragari deposits showed contents of As up to 98.8 and 97.1 wt.%, with impurity contents of Sb up to 1.3 and 6.6 wt.%, and Tl up to 2 and 1.3 wt.%, respectively. Rhombohedral unit-cell parameters for native arsenic from Rujevac and Stragari deposits amount to: a = 3.760(2), c = 10.555(3) Å, V = 129.23(7) Å3 and a = 3.763(1), c = 10.560(5) Å, V = 129.48(8) Å3, respectively. Mineral assemblages, deposition order and genesis of the Rujevac polymetallic deposit were also discussed in detail. Native arsenic mineralization here has been additionally compared with similar well-known global deposits.

  12. ZnO/CdS bi-layer nanostructures photoelectrode for dye-sensitized solar cells

    Science.gov (United States)

    Dalal, Paresh V.; Deshpande, Milind P.; Solanki, Bharat G.; Soni, Saurabh S.

    2016-05-01

    Simple chemical deposition method for the synthesis of ZnO/CdS bilayer photoelectrode on fluorine doped tin oxide (FTO) coated glass substrate in aqueous medium at low temperature (coated glass substrates by dip-coating method, whereas CdS nanorods were successfully synthesized on pre-deposited ZnO film by Chemical Bath Deposition (CBD) method. The Photovoltaic properties of FTO/ZnO/CdS bilayer photo electrodes were also studied. A maximum short circuit current density of 9.1 mA cm-2 and conversion efficiency 1.05% are observed for ZnO/CdS_10min. Layer, which supports fast electron injection kinetics due to hetero structured nanorod, while minimum values of 0.53mA cm-2 and 0.01% respectively are observed for only ZnO deposited layer.

  13. Efficient Z-scheme charge separation in novel vertically aligned ZnO/CdSSe nanotrees

    Science.gov (United States)

    Li, Zhengxin; Nieto-Pescador, Jesus; Carson, Alexander J.; Blake, Jolie C.; Gundlach, Lars

    2016-04-01

    A new tree-like ZnO/CdSSe nanocomposite with CdSSe branches grown on ZnO nanowires prepared via a two-step chemical vapor deposition is presented. The nanotrees (NTs) are vertically aligned on a substrate. The CdSSe branches result in strong visible light absorption and form a type-II heterojunction with the ZnO stem that facilitates efficient electron transfer. A combination of photoluminescence spectroscopy and lifetime measurements indicates that the NTs are promising materials for applications that benefit from a Z-scheme charge transfer mechanism. Vertically aligned branched ZnO nanowires can provide direct electron transport pathways to substrates and allow for efficient charge separation. These advantages of nanoscale hierarchical heterostructures make ZnO/CdSSe NTs a promising semiconductor material for solar cells, and other opto-electronic devices.

  14. Efficient Z-scheme charge separation in novel vertically aligned ZnO/CdSSe nanotrees.

    Science.gov (United States)

    Li, Zhengxin; Nieto-Pescador, Jesus; Carson, Alexander J; Blake, Jolie C; Gundlach, Lars

    2016-04-01

    A new tree-like ZnO/CdSSe nanocomposite with CdSSe branches grown on ZnO nanowires prepared via a two-step chemical vapor deposition is presented. The nanotrees (NTs) are vertically aligned on a substrate. The CdSSe branches result in strong visible light absorption and form a type-II heterojunction with the ZnO stem that facilitates efficient electron transfer. A combination of photoluminescence spectroscopy and lifetime measurements indicates that the NTs are promising materials for applications that benefit from a Z-scheme charge transfer mechanism. Vertically aligned branched ZnO nanowires can provide direct electron transport pathways to substrates and allow for efficient charge separation. These advantages of nanoscale hierarchical heterostructures make ZnO/CdSSe NTs a promising semiconductor material for solar cells, and other opto-electronic devices. PMID:26894995

  15. Photocatalytic degradation of methyl orange over ITO/CdS/ZnO interface composite films

    Institute of Scientific and Technical Information of China (English)

    WEI Shouqiang; SHAO Zhongcai; LU Xudong; LIU Ying; CAO Linlin; HE Yan

    2009-01-01

    ITO/CdS/ZnO interface composite films were successfully prepared by subsequent electrodeposition of CdS and ZnO onto indium tin oxide (ITO) glass substrates. The obtained ITO/CdS/ZnO composite films were characterized with X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV-Vis spectroscopy. The photocatalytic activity of ITO/CdS/ZnO composite films were investigated using methyl orange (MO) as a model organic compound under UV light irradiation. The influence of operating parameters on MO degradation including initial concentration of MO, pH value of solution, and inorganic anion species over the composite films were examined. A blue shift of absorption threshold was observed for the ITO/CdS/ZnO film in comparison with ITO/ZnO film. ITO/CdS/ZnO composite films prepared under specific conditions showed a higher photocatalytic activity than that of ITO/ZnO films. It was also found that the photocatalytic degradation of MO on the composite filing followed pseudo-first order kinetics.

  16. Properties of a New Nonlinear Optical Crystal CdZn2B2O6

    Institute of Scientific and Technical Information of China (English)

    ZHANG Fan; SHEN De-Zhong; SHEN Guang-Qiu; WANG Xiao-Qing

    2008-01-01

    @@ Cadmium dizinc diborate (CdZn2B2O6) single crystals have been grown for the first time. The crystal structure of CdZn2B2O6 is the same as that of the Cd3Zn3B4O12. The x-ray diffraction, infrated and Raman spectra,differential scanning calorimetry analysis and density indicate that the physical and chemical properties of both crystals are very similar. Especially, the nonlinear optical coefficients of CdZn2B2O6 and Cd3ZnaB4O12 crystals are 2.6 and 2.4 times as large as that of KH2PO4 crystal respectively. Chemical etching experiments indicated that these crystals are very stable in neutral solution and not hygroscopic in air at room temperature.

  17. Gas sensing performance of the spray deposited Cd-ZnO thin films

    International Nuclear Information System (INIS)

    Highlights: • Spray deposition of undoped and Cd doped ZnO thin films. • Effect of Cd doping on the gas sensing performance of ZnO was investigated. • Cd 2 at.% doping showed highest acetone sensing performance at low temperature (325 °C). - Abstract: A simple and cost-effective spray pyrolysis technique was employed to deposit undoped and cadmium doped zinc oxide (Cd-ZnO) thin films onto the glass substrates and the deposited films were characterized for their structural, morphological and optical properties. The doping concentration was varied from 1 to 5 at.%. All the films showed the preferred orientation along (0 0 2) plane. However, the (0 0 2) plane was shifted towards the lower 2θ values after Cd doping. The lattice parameters and texture coefficients were obtained by analyzing the XRD patterns. The band gap energies of the films were decreased with increase in Cd concentration. Moreover, the gas sensing properties of the Cd-ZnO films were investigated towards the reducing gases such as Liquefied petroleum gas (LPG), acetone, ethanol and ammonia. The cadmium dopant plays a vital role in fine tuning the physico-chemical properties and consequently gas sensitivity of the ZnO thin films. The sample with 2 at.% Cd doped ZnO (CZO2) showed the maximum gas sensitivity (87%) towards acetone at 325 °C with faster response and recovery time periods of 6 s and 23 s, respectively

  18. Highest-order optical phonon-mediated relaxation in CdTe/ZnTe quantum dots

    International Nuclear Information System (INIS)

    The highest 19th-order longitudinal optical (LO) phonon-mediated relaxation was observed in photoluminescence excitation spectra of CdTe self-assembled quantum dots grown in ZnTe. Hot excitons photoexcited highly in the ZnTe barrier layer are relaxed into the wetting-layer state by emitting multiple LO phonons of the barrier layer successively. Below the wetting-layer state, the LO phonons involved in the relaxation are transformed to those of interfacial ZnxCd1-xTe surrounding CdTe quantum dots. The ZnTe-like and CdTe-like LO phonons of ZnxCd1-xTe and lastly acoustic phonons are emitted in the relaxation into the CdTe dots. The observed main relaxation is the fast relaxation directly into CdTe quantum dots and is not the relaxation through either the wetting-layer quantum well or the band bottom of the ZnTe barrier layer. This observation shows very efficient optical phonon-mediated relaxation of hot excitons excited highly in the ZnTe conduction band through not only the ZnTe extended state but also localized state in the CdTe quantum dots reflecting strong exciton-LO phonon interaction of telluride compounds

  19. Nanoscale morphology of multilayer PbTe/CdTe heterostructures and its effect on photoluminescence properties

    International Nuclear Information System (INIS)

    We study nanoscale morphology of PbTe/CdTe multilayer heterostuctures grown by molecular beam epitaxy on hybrid GaAs/CdTe (100) substrates. Nominally, the structures consist of 25 repetitions of subsequently deposited CdTe and PbTe layers with comparable thicknesses of 21 and 8 nm, respectively. However, the morphology of the resulting structures crucially depends on the growth temperature. The two-dimensional layered, superlattice-like character of the structures remains preserved only when grown at low substrate temperatures, such as 230 °C. The samples grown at the slightly elevated temperature of 270 °C undergo a morphological transformation to structures consisting of CdTe and PbTe pillars and columns oriented perpendicular to the substrate. Although the pillar-like objects are of various shapes and dimensions these structures exhibit exceptionally strong photoluminescence in the near infrared spectral region. At the higher growth temperature of 310 °C, PbTe and CdTe separate completely forming thick layers oriented longitudinally to the substrate plane. The observed topological transformations are driven by thermally activated atomic diffusion in the solid state phase. The solid state phase remains fucrystlly coherent during the processes. The observed topological transitions leading to the material separation in PbTe/CdTe system could be regarded as an analog of spinodal decomposition of an immiscible solid state solution and thus they can be qualitatively described by the Cahn–Hillard model as proposed by Groiss et al (2014 APL Mater. 2 012105). (paper)

  20. Development of electrodeposited ZnTe layers as window materials in ZnTe/CdTe/CdHgTe multi-layer solar cells

    International Nuclear Information System (INIS)

    Zinc telluride (ZnTe) thin films have been deposited on glass/conducting glass substrates using a low-cost electrodeposition method. The resulting films have been characterized using various techniques in order to optimize growth parameters. X-ray diffraction (XRD) has been used to identify the phases present in the films. Photoelectrochemical (PEC) cell and optical absorption measurements have been performed to determine the electrical conductivity type, and the bandgap of the layers, respectively. It has been confirmed by XRD measurement that the deposited layers mainly consist of ZnTe phases. The PEC measurements indicate that the ZnTe layers are p-type in electrical conduction and optical absorption measurements show that their bandgap is in the range 2.10-2.20 eV. p-Type ZnTe window materials have been used in CdTe based solar cell structures, following new designs of graded bandgap multi-layer solar cells. The structures of FTO/ZnTe/CdTe/metal and FTO/ZnTe/CdTe/CdHgTe/metal have been investigated. The results are presented in this paper using observed experimental data

  1. Symmetry of high-piezoelectric Pb-based complex perovskites at the morphotropic phase boundary I. Neutron diffraction study on Pb(Zn1/3Nb2/3)O3 -9%PbTiO3

    OpenAIRE

    Uesu, Yoshiaki; Matsuda, Masaaki; Yamada, Yasusada; Fujishiro, Kouji; Cox, Dave E.; Noheda, Beatriz; Shirane, Gen

    2001-01-01

    The symmetry was examined using neutron diffraction method on Pb(Zn1/3Nb2/3)O3 -9%PbTiO3 (PZN/9PT) which has a composition at the morphotropic phase boundary (MPB) between Pb(Zn1/3Nb2/3)O3 and PbTiO3. The results were compared with those of other specimens with same composition but with different prehistory. The equilibrium state of all examined specimens is not the mixture of rhombohedral and tetragonal phases of the end members but exists in a new polarization rotation line Mc# (orthorhombi...

  2. Effect of competing cations (Cu, Zn, Mn, Pb) adsorbed by natural zeolite

    OpenAIRE

    Zendelska, Afrodita; Golomeova, Mirjana

    2014-01-01

    The aim of this work was to investigate the influence of the presence of competing cations on the individual adsorption of Cu2+, Pb2+, Zn2+ and Mn2+ from a solution containing a mixture of all these metal ions, by natural zeolite. In this work is shown compares the adsorption of each heavy metal ion from both single- and multi-component solutions. The amount adsorbed from multi-component solutions was affected significantly, except for Pb2+ where the difference between single and multi-compon...

  3. Influence of Zn-Cd substitution: Spectroscopic and theoretical investigation of 8-hydroxyquinoline complexes

    Science.gov (United States)

    Ramalho, Teodorico C.; Martins, Tales L. C.; Borges, Luiz E. Pizarro; de Pinho, Marcos Henrique; de Avillez, Roberto Ribeiro; da Cunha, Elaine F. F.

    2009-05-01

    It is now well known that zinc is crucial for the synthesis of nucleic acids and, consequently, for cellular division. However, 67Zn, the NMR-detectable isotope, is one of the isotopes most poorly studied by NMR. The strategy used for NMR studies is the substitution of Zn by 113Cd. In this work, we employed 13C, 113Cd NMR (CPMAS), X-ray and DFT calculation in order to evaluate the Zn-Cd substitution using 8-hydroxyquinoline like prototype compound. Our results show that there are strong structural and electronics effects are involved in the substitution.

  4. Biosorption kinetics of Cd (II, Cr (III and Pb (II in aqueous solutions by olive stone

    Directory of Open Access Journals (Sweden)

    M. Calero

    2009-06-01

    Full Text Available A by-product from olive oil production, olive stone, was investigated for the removal of Cd (II, Cr (III and Pb (II from aqueous solutions. The kinetics of biosorption are studied, analyzing the effect of the initial concentration of metal and temperature. Pseudo-first-order, pseudo-second-order, Elovich and intraparticle diffusion models have been used to represent the kinetics of the process and obtain the main kinetic parameters. The results show that the pseudo-second order model is the one that best describes the biosorption of the three metal ions for all the range of experimental conditions investigated. For the three metal ions, the maximum biosoption capacity and the initial biosorption rate increase when the initial metal concentration rises. However, the kinetic constant decreases when the initial metal concentration increases. The temperature effect on biosorption capacity for Cd (II and Cr (III is less significant; however, for Pb (II the effect of temperature is more important, especially when temperature rises from 25 to 40ºC. The biosorption capacity at mmol/g of olive stone changes in the following order: Cr>Cd>Pb. Thus, for an initial concentration of 220 mg/ℓ, a maximum sorption capacity of 0.079 mmol/g for Cr (III, 0.065 mmol/g for Cd (II and 0.028 mmol/g for Pb (II has been obtained.

  5. Potential of Azolla caroliniana for the removal of Pb and Cd from wastewaters

    Directory of Open Access Journals (Sweden)

    A. Wolińska

    2005-09-01

    Full Text Available Heavy metals constitute a serious health risk because they accumulate in soils, water and organisms. One of the methods of removing these pollutants from water and soil is the use of plants (phytoremediation. There are many plants (hyperaccumulators which have the ability to accumulate large amounts of heavy metals. One of them is the aquatic fern Azolla sp., which can bind some substances. The aim of this study was to verify the ability of Azolla caroliniana Willd. (Azollaceae to fix Pb and Cd from polluted waters. During the experiment, A. caroliniana was grown in water solution enriched in Pb(II and Cd(II, each at concentrations of 0.1, 0.5 and 1 mg dm-3. The presence of lead and cadmium ions caused an inhibition of A. caroliniana growth by about 30-37 and 24-47%, respectively. After the end of the experiment, the content of the metals tested was determined in the medium and in the biomass (after mineralization. In the water medium, the decrease of Pb(II amounted to 90% and that of Cd(II to 22%. In the A. caroliniana tissues, the content of lead was up to 416 mg Pb per kg d.m., and that of cadmium – up to 259 mg Cd per kg d.m.

  6. Removal of Cd, Cr, and Pb from aqueous solution by unmodified and modified agricultural wastes.

    Science.gov (United States)

    Mahmood-Ul-Hassan, Muhammad; Suthor, Vishandas; Rafique, Ejaz; Yasin, Muhammad

    2015-02-01

    The adsorption of cadmium (Cd), chromium (Cr), and lead (Pb), widely detected in wastewater, by unmodified and modified banana stalks, corn cob, and sunflower achene was explored. The three agricultural wastes were chemically modified with sodium hydroxide (NaOH), in combination with nitric acid (HNO3) and sulfuric acid (H2SO4), in order to improve their adsorptive binding capacity. The experiments were conducted as a function of contact time and initial metal ion concentrations. Of the three waste materials, corn cob had the highest adsorptive capacity for Pb than Cr and Cd. The NaOH-modified substrates had higher adsorptive capacity than the acid modified samples. The chemical treatment invariably increased the adsorption capacity between 10 and 100 %. The Langmuir maximum sorption capacity (q m) of Pb was highest (21-60 mg g(-1) of banana, 30-57 mg g(-1) of corn cob, and 23-28 mg g(-1) of sunflower achene) and that of Cd was least (4-7 mg g(-1) of banana, 14-20 mg g(-1) of corn cob, and 11-16 mg g(-1) of sunflower achene). The q m was in the order of Pb > Cr > Cd for all the three adsorbents. The results demonstrate that the agricultural waste materials used in this study could be used to remediate water polluted with heavy metals. PMID:25626568

  7. Surface tension of Hg-M (M - Cd, In, Sn, Tl, Pb, Bi) system amalgams

    International Nuclear Information System (INIS)

    Temperature and concentration dependences of surface tension of liquid amalgams of Hg-M binary systems (M - Cd, In, Sn, Tl, Pb, Bi) were studied. The revealed correlation of surface tension and electric conductivity of amalgams was explained by peculiarities of mercury energy spectrum, changes of density on Fermi level, adsorption processes and changes of surface layer thickness. 19 refs.; 8 figs.; 4 tabs

  8. Numerical study of the influence of ZnTe thickness on CdS/ZnTe solar cell performance

    Science.gov (United States)

    Skhouni, Othmane; El Manouni, Ahmed; Mari, Bernabe; Ullah, Hanif

    2016-05-01

    At present most of II-VI semiconductor based solar cells use the CdTe material as an absorber film. The simulation of its performance is realized by means of various numerical modelling programs. We have modelled a solar cell based on zinc telluride (ZnTe) thin film as absorber in substitution to the CdTe material, which contains the cadmium element known by its toxicity. The performance of such photovoltaic device has been numerically simulated and the thickness of the absorber layer has been optimized to give the optimal conversion efficiency. A photovoltaic device consisting of a ZnTe layer as absorber, CdS as the buffer layer and ZnO as a window layer was modelled through Solar Cell Capacitance Simulator Software. Dark and illuminated I-V characteristics and the results for different output parameters of ZnO/CdS/ZnTe solar cell were analyzed. The effect of ZnTe absorber thickness on different main working parameters such as: open-circuit voltage Voc, short-circuit current density Jsc, fill factor FF, photovoltaic conversion efficiency η was intensely studied in order to optimize ZnTe film thickness. This study reveals that increasing the thickness of ZnTe absorber layer results in higher efficiency until a maximum value and then decreases slightly. This maximum was found to be 10% at ZnTe optimum thickness close to 2 µm. Contribution to the topical issue "Materials for Energy Harvesting, Conversion and Storage (ICOME 2015) - Elected submissions", edited by Jean-Michel Nunzi, Rachid Bennacer and Mohammed El Ganaoui

  9. Determination of Cd, Pb and As in sediments of the Sava River by electrothermal atomic absorption spectrometry

    Directory of Open Access Journals (Sweden)

    SIMONA MURKO

    2010-01-01

    Full Text Available The applicability of nitric acid, palladium nitrate and a mixture of palladium and magnesium nitrate as matrix modifiers were estimated for the accurate and reproducible determination of cadmium (Cd, lead (Pb and arsenic (As in sediments of the Sava River by electrothermal atomic absorption spectrometry, ETAAS. Decomposition of the samples was done in a closed vessel microwave-assisted digestion system using nitric, hydrochloric and hydrofluoric acids, followed by the addition of boric acid to convert the fluorides into soluble complexes. The parameters for the determination of Cd, Pb and As in sediments were optimised for each individual element and for each matrix modifier. In addition, two sediment reference materials were also analysed. In determination of Cd and Pb, nitric acid was found to be the most appropriate matrix modifier. The accurate and reliable determination of Cd and Pb in sediments was possible also in the presence of boric acid. The use of a mixture of palladium and magnesium nitrate efficiently compensated for matrix effects and enabled the accurate and reliable determination of As in the sediments. Quantification of Cd and As was performed by calibration using acid matched standard solutions, while the standard addition method was applied for the quantification of Pb. The repeatability of the analytical procedure for the determination of Cd, Pb and As in sediments was ±5 % for Cd, ±4 % for Pb and ±2 % for As. The LOD values of the analytical procedure were found to be 0.05 mg/kg for Cd and 0.25 mg/kg for Pb and As, while the LOQ values were 0.16 mg/kg for Cd and 0.83 mg/kg for Pb and As. Finally, Cd, Pb and As were successfully determined in sediments of the Sava River in Slovenia.

  10. Probing photoluminescence dynamics of colloidal CdSe/ZnS core/shell nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Kaur, Gurvir; Tripathi, S.K., E-mail: surya@pu.ac.in

    2014-11-15

    The paper presents the synthesis of thiol capped CdSe/ZnS core/shell nanoparticles with CdSe core and ZnS shell. The thickness of the ZnS shell has been controlled by the regulating the amount of Zn/S precursors for reaction. The steady and transient photoluminescence properties substantiate the growth of ZnS shell over the CdSe cores. High resolution transmission electron microscope and the X-ray diffraction patterns reveal nanocrystalline particles of an average size 3.4 nm packed in wurtzite lattice. Photoluminescence excitation spectra as well as the excitation–emission matrix of CdSe and CdSe/ZnS evidence the growth of ZnS for Type I hetero-junction without interfering the energy states of core. By this method, ZnS layer of 8.84 Å is optimum for fluorescence enhancement of the core/shell quantum dots. The multiexponential fluorescence decay of the quantum dots represents independent radiative recombinations with overlapped energies. It is revealed that the average fluorescence lifetimes of quantum dots decreased with increase in ZnS shell, which is due to the enhanced contribution from initially populated excitonic recombination and the reduction in the surface trap states with shell growth. - Highlights: • Synthesis of MAA capped CdSe/ZnS core/shell QDs with different shell thicknesses. • Shell thickness has been controlled by the amount of shell precursors added. • ZnS shell significantly enhanced the fluorescence quantum yield of QDs. • Superposition of quantum confinement energy model employed for shell thickness. • Probed the fluorescence dynamics of QDs by time resolved fluorescence spectroscopy.

  11. Dual emission in asymmetric ``giant'' PbS/CdS/CdS core/shell/shell quantum dots

    Science.gov (United States)

    Zhao, Haiguang; Sirigu, Gianluca; Parisini, Andrea; Camellini, Andrea; Nicotra, Giuseppe; Rosei, Federico; Morandi, Vittorio; Zavelani-Rossi, Margherita; Vomiero, Alberto

    2016-02-01

    Semiconducting nanocrystals optically active in the infrared region of the electromagnetic spectrum enable exciting avenues in fundamental research and novel applications compatible with the infrared transparency windows of biosystems such as chemical and biological optical sensing, including nanoscale thermometry. In this context, quantum dots (QDs) with double color emission may represent ultra-accurate and self-calibrating nanosystems. We present the synthesis of giant core/shell/shell asymmetric QDs having a PbS/CdS zinc blende (Zb)/CdS wurtzite (Wz) structure with double color emission close to the near-infrared (NIR) region. We show that the double emission depends on the excitation condition and analyze the electron-hole distribution responsible for the independent and simultaneous radiative exciton recombination in the PbS core and in the CdS Wz shell, respectively. These results highlight the importance of the driving force leading to preferential crystal growth in asymmetric QDs, and provide a pathway for the rational control of the synthesis of double color emitting giant QDs, leading to the effective exploitation of visible/NIR transparency windows.Semiconducting nanocrystals optically active in the infrared region of the electromagnetic spectrum enable exciting avenues in fundamental research and novel applications compatible with the infrared transparency windows of biosystems such as chemical and biological optical sensing, including nanoscale thermometry. In this context, quantum dots (QDs) with double color emission may represent ultra-accurate and self-calibrating nanosystems. We present the synthesis of giant core/shell/shell asymmetric QDs having a PbS/CdS zinc blende (Zb)/CdS wurtzite (Wz) structure with double color emission close to the near-infrared (NIR) region. We show that the double emission depends on the excitation condition and analyze the electron-hole distribution responsible for the independent and simultaneous radiative exciton

  12. A new LiNbO3-type polar oxide with closed-shell cations: ZnPbO3

    International Nuclear Information System (INIS)

    A new lithium-niobate (LiNbO3)-type polar compound, namely, ZnPbO3 (a = 5.41605(7) Å and c = 14.33151(3) Å), with closed-shell ions only was synthesized under high pressure and high temperature (8 GPa and 1273 K). A point-charge-model calculation based on atomic positions refined by Rietveld analysis of synchrotron X-ray diffraction data gave an electrical ionic polarization of 77 μC/cm2 along the hexagonal c-axis. Detailed structural analysis indicated that the contribution of Pb4+ in ZnPbO3 to the polarization was almost twice as large as that of Sn4+ in ZnSnO3. Transport measurement showed metallic behavior of ZnPbO3 from room temperature to low temperature despite the fact that both cations are closed-shell ions

  13. Field evaluation of Cd and Zn phytoextraction potential by the hyperaccumulators Thlaspi caerulescens and Arabidopsis halleri

    Energy Technology Data Exchange (ETDEWEB)

    McGrath, S.P. [Agriculture and the Environment Division, Rothamsted Research, Harpenden, Herts AL5 2JQ (United Kingdom)]. E-mail: steve.mcgrath@bbsrc.ac.uk; Lombi, E. [Agriculture and the Environment Division, Rothamsted Research, Harpenden, Herts AL5 2JQ (United Kingdom); Gray, C.W. [Agriculture and the Environment Division, Rothamsted Research, Harpenden, Herts AL5 2JQ (United Kingdom); Caille, N. [Agriculture and the Environment Division, Rothamsted Research, Harpenden, Herts AL5 2JQ (United Kingdom); Dunham, S.J. [Agriculture and the Environment Division, Rothamsted Research, Harpenden, Herts AL5 2JQ (United Kingdom); Zhao, F.J. [Agriculture and the Environment Division, Rothamsted Research, Harpenden, Herts AL5 2JQ (United Kingdom)

    2006-05-15

    Field trials were undertaken to investigate the effect of the application of metal mobilizing agents, different sowing strategies and length of growing season on the extraction of Cd and Zn from soils by Thlaspi caerulescens and Arabidopsis halleri. None of the mobilizing agents used enhanced metal accumulation by T. caerulescens. Between 1998 and 2000, on average across plots where Cd or Zn exceeded allowable limits, T. caerulescens removed 1.3 and 0.3% of the total soil Cd and Zn. In one season when T. caerulescens was grown for 14 months, 21.7 and 4.4% of the total soil Cd and Zn was removed. This was larger than values found when T. caerulescens was grown for 4 months. A. halleri accumulated similar concentrations of Zn, but lower Cd concentrations than T. caerulescens. The results indicate that metal phytoextraction using T. caerulescens can be used to clean up soils moderately contaminated by Cd. - The hyperaccumulator Thlaspi caerulescens (the Ganges ecotype) is more efficient at phytoextracting Cd than Zn from contaminated soil.

  14. Field evaluation of Cd and Zn phytoextraction potential by the hyperaccumulators Thlaspi caerulescens and Arabidopsis halleri

    International Nuclear Information System (INIS)

    Field trials were undertaken to investigate the effect of the application of metal mobilizing agents, different sowing strategies and length of growing season on the extraction of Cd and Zn from soils by Thlaspi caerulescens and Arabidopsis halleri. None of the mobilizing agents used enhanced metal accumulation by T. caerulescens. Between 1998 and 2000, on average across plots where Cd or Zn exceeded allowable limits, T. caerulescens removed 1.3 and 0.3% of the total soil Cd and Zn. In one season when T. caerulescens was grown for 14 months, 21.7 and 4.4% of the total soil Cd and Zn was removed. This was larger than values found when T. caerulescens was grown for 4 months. A. halleri accumulated similar concentrations of Zn, but lower Cd concentrations than T. caerulescens. The results indicate that metal phytoextraction using T. caerulescens can be used to clean up soils moderately contaminated by Cd. - The hyperaccumulator Thlaspi caerulescens (the Ganges ecotype) is more efficient at phytoextracting Cd than Zn from contaminated soil

  15. Effects of Sewage Sludge and Chemical Fertilizers on Pb and Cd Accumulation in Fenugreek (Trigonella gracum

    Directory of Open Access Journals (Sweden)

    Mehrdad Cheraghi

    2015-09-01

    Full Text Available Background: Reprocessing of sewage sludge to agricultural land is preferred to disposal through landfill or incineration due to its potentially beneficial effects on soil fertility from organic matter and plant nutrients, such as N and P, present in the sludge. Therefore, this study was conducted to investigate the impact of sewage sludge and chemical fertilizers on Pb and Cd accumulation in fenugreek, Trigonella gracum. Methods: The experiment was carried out in earthen pots, 30 cm in diameter and 30 cm in depth. The study was done on five groups- control, S1: sewage sludge (50 tone/ha, S2: sew-age sludge (50 tone/ha+heavy metals [85 ppm of Cd(Cl2; 840 ppm of Pb(NO32], F1: chemi-cal fertilizer (250 kg/ha, and F2: chemical fertilizer (250 kg/ha+ heavy metals [85 ppm of Cd(Cl2; 840 ppm of Pb(NO32]- in three replicates. Results: The results showed that total Pb concentrations ranged from 0.05 to 2 mg/kg, with the maximum level in the sewage sludge treatment (S2 while Cd concentrations in the plant ranged from 0.07 to 1.1 mg/kg with the maximum content in the chemical fertilizer treatment (F2. The concentrations of Pb and Cd in vegetables were significantly higher than the permis-sible limits. Conclusion: This study highlights the potential risks involved in the cultivation and consump-tion of vegetables on plots irrigated with sewage sludge, a practice which may endanger the health of urban populations that consume these vegetables.

  16. Determination of Cd, Cr and Pb in phosphate fertilizers by laser-induced breakdown spectroscopy

    International Nuclear Information System (INIS)

    A validated method for quantitative determination of Cd, Cr, and Pb in phosphate fertilizers by laser-induced breakdown spectroscopy (LIBS) is presented. Laboratory samples were comminuted and homogenized by cryogenic or planetary ball milling, pressed into pellets and analyzed by LIBS. The experimental setup was designed by using a Q-switched Nd:YAG at 1064 nm with 10 Hz repetition rate, and the intensity signals from Cd II 214.441 nm, Cr II 267.716 nm and Pb II 220.353 nm emission lines were measured by using a spectrometer furnished with an intensified charge-coupled device. LIBS parameters (laser fluence, lens-to-sample distance, delay time, integration time gate, number of sites and number of laser pulses per site) were chosen after univariate experiments with a pellet of NIST SRM 695 (Trace Elements in Multi-Nutrient Fertilizer). Calibration and validation were carried out with 30 fertilizer samples from single superphosphate, triple superphosphate, monoammonium phosphate, and NPK mixtures. Good results were obtained by using 30 pulses of 50 J cm−2 (750 μm spot size), 2.0 μs delay time and 5.0 μs integration time gate. No significant differences between Cd, Cr, and Pb mass fractions determined by the proposed LIBS method and by ICP OES after microwave-assisted acid digestion (AOAC 2006.03 Official Method) were found at 95% confidence level. The limits of detection of 1 mg kg−1 Cd, 2 mg kg−1 Cr and 15 mg kg−1 Pb and the precision (coefficients of variation of results ranging from 2% to 15%) indicate that the proposed LIBS method can be recommended for the determination of these analytes in phosphate fertilizers. - Highlights: • First LIBS application for quantitative Cd, Cr and Pb determination in fertilizers. • LIBS method was validated for analysis of phosphate fertilizers pressed pellets. • LIBS sample throughput is remarkably better than already existing methods

  17. Environmental impact and potential remedation of contaminated land affected by Zn-Pb mining.

    OpenAIRE

    Cappuyns, Valérie; Swennen, Rudy; Ganne, P; Niclaes, M

    2005-01-01

    International Workshop Current developments in remediation of contaminated lands 27 - 29 October 2005, Pulawy, Poland Environmental impact and potential remediation of contaminated land affected by Zn-Pb mining Valérie Cappuyns*1, Rudy Swennen1, Patrick Ganne1,2 and Marjan Niclaes1 1Katholieke Universiteit Leuven, Fysico-chemische Geologie, Celestijnenlaan 200C, B-3001 Heverlee, Belgium 2 Katholieke Universiteit Leuven, Mijnbouw, Kasteelpark Arenberg 40, B-3001 Heverlee, Belgium 1. Introducti...

  18. Extremely High Phosphate Sorption Capacity in Cu-Pb-Zn Mine Tailings

    OpenAIRE

    Huang, Longbin; Li, Xiaofang; Tuan A H Nguyen

    2015-01-01

    Elevated inorganic phosphate (Pi) concentrations in pore water of amended tailings under direct revegetation may cause toxicity in some native woody species but not native forbs or herb species, all of which are key constituents in target native plant communities for phytostabilizing base metal mine tailings. As a result, Pi sorption capacity has been quantified by a conventional batch procedure in three types of base metal mine tailings sampled from two copper (Cu)-lead (Pb)-zinc (Zn) mines,...

  19. Exciton-Phonon Scattering in CdSe/ZnSe Quantum Dots

    Institute of Scientific and Technical Information of China (English)

    张立功; 申德振; 范希武; 吕少哲

    2002-01-01

    A temperature-dependent photoluminescence measurement is performed in CdSe/ZnSe quantum dots with a ZnCdSe quantum well. We deduce the temperature dependence of the exciton linewidth and peak energy of the zero-dimensional exciton in the quantum dots and two-dimensional exciton in the CdSe wetting layer. The experimental data reveal a reduction of homogeneous broadening of the exciton line in the quantum dots in comparison with that in the two-dimensional wetting layer, which indicates the decrease of exciton and optical phonon coupling in the CdSe quantum dots.

  20. Positron annihilation spectroscopy of vacancy-related defects in CdTe:Cl and CdZnTe:Ge at different stoichiometry deviations

    OpenAIRE

    L. Šedivý; J. Čížek; Belas, E.; Grill, R.; Melikhova, O.

    2016-01-01

    Positron annihilation spectroscopy (PAS) was used to examine the effect of defined Cd-rich and Te-rich annealing on point defects in Cl-doped CdTe and Ge-doped CdZnTe semi-insulating single crystals. The as-grown crystals contain open-volume defects connected with Cd vacancies . It was found that the Cd vacancies agglomerate into clusters coupled with Cl in CdTe:Cl, and in CdZnTe:Ge they are coupled with Ge donors. While annealing in Cd pressure reduces of the density, subsequent annealing in...

  1. Heavy Metals Pollution and Pb Isotopic Signatures in Surface Sediments Collected from Bohai Bay, North China

    OpenAIRE

    Bo Gao; Jin Lu; Hong Hao; Shuhua Yin; Xiao Yu; Qiwen Wang; Ke Sun

    2014-01-01

    To investigate the characteristics and potential sources of heavy metals pollution, surface sediments collected from Bohai Bay, North China, were analyzed for the selected metals (Cd, Cr, Cu, Ni, Pb, and Zn). The Geoaccumulation Index was used to assess the level of heavy metal pollution. Pb isotopic compositions in sediments were also measured to effectively identify the potential Pb sources. The results showed that the average concentrations of Cd, Cr, Cu, Ni, Pb, and Zn were 0.15, 79.73, 2...

  2. Using DGT passive samplers and MC-ICPMS to determine Pb and Zn isotopic signature of groundwaters.

    OpenAIRE

    Desaulty, Anne-Marie; Millot, Romain; Guerrot, Catherine; Berho, Catherine

    2014-01-01

    International audience Several studies have shown the interest of Zinc (Zn) and lead (Pb) isotopic compositions to track anthropogenic pollutions in surface water and groundwater [1-2]. However, given the low content in Pb and Zn in natural waters, several litres are needed to perform a single isotopic analysis by MC-ICPMS. One solution is to use passive DGT (diffusive gradients in thin films) samplers for in-situ pre-concentration of these metals. In these devices, metals are immobilized ...

  3. Fast evolution of tropospheric Pb- and Zn-rich particles in the vicinity of a lead smelter

    Science.gov (United States)

    Choël, M.; Deboudt, K.; Flament, P.; Lecornet, G.; Perdrix, E.; Sobanska, S.

    Dusts collected on air filters at a Pb-Zn refinery located in northern France were sampled in 1997, 1999 and 2002. The low temporal variability in major elements (Pb, Zn and S) abundances suggested chemical composition of particulate emissions was stable over time. In July 2001 and March 2002, atmospheric aerosols were sampled in the vicinity of the Pb-Zn refinery upwind and downwind from the smelters. Bulk concentrations of major elements (Al, Fe, Pb and Zn) and hydrosoluble ions (Na +, NH 4+, Mg 2+, K +, Ca 2+, Cl - NO 3- and SO 42-) were, respectively, determined by atomic absorption spectrometry and ion chromatography. Elemental and molecular individual particle analyses were, respectively, performed by automated SEM-EDX and Raman microspectrometry. Continental air masses (campaign 2001) were characterized by low Na + and high SO 42-, NO 3- and NH 4+ contents upwind from the smelters. Individual particle analysis of Pb- and Zn-rich airborne particles collected downwind from the refinery indicated elemental associations and molecular speciation were similar to those obtained at the emission: Pb compounds were mainly identified as oxides, sulfates and oxy-sulfates whereas Zn compounds were identified as sulfides. Marine air masses (campaign 2002) were characterized by high Na + contents upwind from the smelters. Individual particle analysis of Pb- and Zn-rich particles collected downwind from the refinery pointed out a systematic association with Na, not emitted by the refinery, suggesting internal mixing of marine aerosols with heavy-metals dusts emitted by the refinery. Such fast evolution of airborne particles chemical composition in the vicinity of the refinery was further proven by SEM-EDX and Raman microspectrometry mappings showing physical evolution by aggregation or coagulation of Zn- and Pb-rich particles with aged sea-salts.

  4. Leaching behavior of Pb and Zn in air pollution control residues and their modeling prediction

    Institute of Scientific and Technical Information of China (English)

    ZHANG Hua; HE Pin-jing; SHAO Li-ming; FENG Jun-hui; CAO Qun-ke

    2006-01-01

    Increasing attention has been paid to air pollution control (APC) residues in China recently due to the rising proportion of waste incineration and the hazardous characteristics of the residues, among which heavy metal leaching toxicity plays an important role. Leaching behavior and potential risk of Pb and Zn in the APC residues from a Shanghai municipal solid waste (MSW) incinerator was studied, based on the leaching tests under different conditions and theoretical calculation using a geochemical thermodynamic equilibrium model MINTEQA2. Results showed that, extractant species and liquid to solid (L/S) ratio predominantly controlled the leaching toxicity of Pb and Zn, while ionic strength, vibration method and leaching time had less effect on the metals release.Leachate/final pH determined the metal leaching behavior, which changed the speciation of heavy metals in the extraction system. The equilibrium aqueous speciation, precipitation-dissolution of Pb and Zn was investigated according to the model computation, which was well in agreement with the experimental results.

  5. Fractal structures in two-metal electrodeposition systems I: Pb and Zn

    International Nuclear Information System (INIS)

    Pattern formation in two-metal electrochemical deposition has been scarcely explored in the chemical literature. In this paper, we report new experiments on zinc-lead fractal co-deposition. Electrodeposits are grown in special cells at a fixed large value of the zinc ion concentration, while that of the lead ion is increased gradually. A very wide diversity of morphologies are obtained and classified. Most of the deposited domains are almost exclusively Pb or Zn. But certain regions originating at the base cathode, ranging from a short grass alley to dense, grown-up bushes or shrubs, manifest a combined Pb-Zn composition. Composition is determined using scanning electron microscopy/energy dispersive x ray measurements as well atomic absorption spectroscopy. Pb domains are characterized by shiny leaf-like and dense deposits as well as flowers with round, balloon-like corollas. The Zn zones display a greater variety of morphologies such as thick trunks and thin and fine branching, in addition to minute ''cigar flower'' structures. The various morphologies are analyzed and classified from the viewpoint of fractal nature, characterized by the box-count fractal dimension. Finally, macroscopic spatial alternation between two different characteristic morphologies is observed under certain conditions.

  6. Fractal structures in two-metal electrodeposition systems I: Pb and Zn

    Energy Technology Data Exchange (ETDEWEB)

    Nakouzi, Elias; Sultan, Rabih [Department of Chemistry, American University of Beirut, P. O. Box 11-0236, Riad El Solh, 1107 2020 Beirut (Lebanon)

    2011-12-15

    Pattern formation in two-metal electrochemical deposition has been scarcely explored in the chemical literature. In this paper, we report new experiments on zinc-lead fractal co-deposition. Electrodeposits are grown in special cells at a fixed large value of the zinc ion concentration, while that of the lead ion is increased gradually. A very wide diversity of morphologies are obtained and classified. Most of the deposited domains are almost exclusively Pb or Zn. But certain regions originating at the base cathode, ranging from a short grass alley to dense, grown-up bushes or shrubs, manifest a combined Pb-Zn composition. Composition is determined using scanning electron microscopy/energy dispersive x ray measurements as well atomic absorption spectroscopy. Pb domains are characterized by shiny leaf-like and dense deposits as well as flowers with round, balloon-like corollas. The Zn zones display a greater variety of morphologies such as thick trunks and thin and fine branching, in addition to minute ''cigar flower'' structures. The various morphologies are analyzed and classified from the viewpoint of fractal nature, characterized by the box-count fractal dimension. Finally, macroscopic spatial alternation between two different characteristic morphologies is observed under certain conditions.

  7. Evaluation of potential of adsorption of U, Th, Pb, Zn and Ni by coconut fibers

    International Nuclear Information System (INIS)

    The residual biomass from agricultural activities has been evaluated as biosorbent for metals and organic composts from aqueous solutions, because of its adsorptive properties, low cost, abundance and to be a renewable resource. In this work, the efficiency of coir pith as biosorbent for the removal of U, Th, Pb, Zn e Ni ions from the aqueous solutions is presented. The coir pith is a by-product of the harvest of the coconut, a renewable natural source. The study was conducted by batch method. The influence of pH from 1 to 8, the dosage of the coir pith and the equilibrium time were studied. The adsorption of metal ions increased with the increase of pH and the dose. The Langmuir and Freundlich models were applied to describe the adsorption equilibrium isotherm. The kinetic process was studied using the pseudo-first order and pseudo-second order models. The Gibbs free energy was calculated. In the concentration range of 100 mg.L-1 - 500 mg.L-1, the adsorption process was described better by the Langmuir equation for Pb2+ and Zn2+ ions and the Freundlich equation for UO2 2+, Th4+ and Ni2+ ions, and represented by the pseudo-second order model. The biosorption process for removal of metal ions from the solutions was considered spontaneous. The results were promising, showing perspectives of application of coir pith as biosorbent of U, Th, Pb, Zn and Ni ions in wastewater treatment processes. (author)

  8. Assessment of the Bioavailability of Cu, Pb, and Zn through Petunia axillaris in Contaminated Soils

    Directory of Open Access Journals (Sweden)

    Lydia Bondareva

    2014-01-01

    Full Text Available Heavy metals are potentially toxic to human life and the environment. Metal toxicity depends on chemical associations in soils. For this reason, determining the chemical form of a metal in soils is important to evaluate its mobility and the potential accumulation. The aim of this examination is to evaluate the accumulation potential of Petunia x hybrida as a flower crop for three metals, namely, copper (Cu, lead (Pb, and nickel (Ni. Trace metals (Zn, Cu, and Pb in the soils were partitioned by a sequential extraction procedure into H2O extractable (F1, 1 M CH3COONa extractable (F2. Chemical fractionation showed that F1 and F2 fraction of the metals were near 1% and residue was the dominant form for Zn, Cu, and Pb in all samples. Using fluorescence method allowed us to estimate condition of the plants by adding metals. As result of plant and soil analysis, we can conclude that Petunia has Cu, Zn, and Ni tolerance and accumulation. Therefore, Petunia has the potential to serve as a model species for developing herbaceous, ornamental plants for phytoremediation.

  9. Synthesis of PbS/Ni2+ doped CdS quantum dots cosensitized solar cells: Enhanced power conversion efficiency and durability

    International Nuclear Information System (INIS)

    Highlights: •The synthetic of PbS/NCdS/TiO2 photoanode with a simple method. •The power conversion efficiency of the PbS/NCdS/TiO2 is 3.60 %. •The effects of photovoltaic performances caused by doped with Ni2+ were studied. •ZnS passivation layer enhanced electron lifetime significantly. •Ni2+ doped CdS is an effective way to enhance the energy conversion efficiency. -- Abstract: A new photoanode by employing Ni2+ doping of CdS used to fabricate PbS and Ni2+ doped CdS cosensitized quantum dot-sensitized solar cell (QDSSCs). Under AM 1.5 G (100 mW/cm2) illumination, the cell device exhibit a power conversion efficiency (η) of 3.60 %, which is higher than the value of 2.65 % obtained with CdS without dopant. The improved photoelectric performance is due to the impurities from Ni2+ doping of CdS, which have an impact on the electronic and photophysical properties, and the dopant creates electronic states in the midgap region of CdS thus altering the charge separation and recombination dynamics. Furthermore, the cell device based on the Ni2+ doped CdS photoanode shows superior stability in the sulfide/polysulfide electrolyte, resulting in a highly reproducible performance, which is a serious challenge for the Ni2+ doped solar cell. This finding can provide an effective method for the fabrication of new photoanode, which can pave the way to further improve the power conversion efficiency of the future QDSSCs

  10. Performance simulation and structure design of Binode CdZnTe gamma-ray detector

    International Nuclear Information System (INIS)

    A new electrode structure CdZnTe (Cadmium Zinc Telluride) detector named Binode CdZnTe has been pro- posed in this paper. Together with the softwares of MAXWELL, GEANT4, and ROOT, the charge collection process and its gamma spectrum of the detector have been simulated and the detector structure has been optimized. In order to improve its performance further, Compton scattering effect correction has been used. The simulation results demonstrate that with refined design and Compton scattering effect correction, Binode CdZnTe detectors is capable of achieving 3.92% FWHM at 122 keV, and 1.27% FWHM at 662 keV. Com- pared with other single-polarity (electron-only) detector configurations, Binode CdZnTe detector offers a cost effective and simple structure alternative with comparable energy resolution. (authors)

  11. First-Principles Study on Cd Doping in Cu2ZnSnS4 and Cu2ZnSnSe4

    Science.gov (United States)

    Maeda, Tsuyoshi; Nakamura, Satoshi; Wada, Takahiro

    2012-10-01

    To quantitatively evaluate the substitution energies of Cd atom for Cu, Zn, or Sn atom in indium-free photovoltaic semiconductors Cu2ZnSnS4 (CZTS) and Cu2ZnSnSe4 (CZTSe), first-principles pseudopotential calculations using plane-wave basis functions were performed. The substitution energies of Cd atom in kesterite-type CZTS and CZTSe were calculated in consideration of the atomic chemical potentials of the constituent elements of Cu, Zn, Sn, and the doping atom of Cd. During the chemical bath deposition (CBD) of the CdS layer on the CZTS or CZTSe layer, Cu, Zn, and Cd atoms dissolved in the ammonia aqueous solution and formed [Cu(NH3)2]+, [Zn(NH3)4]2+, and [Cd(NH3)4]2+ complex ions. Therefore, the chemical potentials of Cu, Zn, and Cd atoms in [Cu(NH3)2]+, [Zn(NH3)4]2+, and [Cd(NH3)4]2+ complex ions were calculated. We found that the substitution energies of n-type CdCu and charge-neutral CdZn in CZTS and CZTSe are smaller than that of p-type CdSn. The substitution energies of CdCu in CZTS and CZTSe are smaller than that in chalcopyrite-type CuInSe2 (CIS). However, the substitution energies of CdCu, CdZn, and CdSn are positive values. The formation energy of charge-neutral Cd doping with the Cu vacancy (CdCu + VCu) pair is a negative value and greatly smaller than those of donor-type CdCu and neutral CdZn in CZTS and CZTSe. These results indicate that the charge-neutral (CdCu + VCu) vacancy pair is easily formed during the CBD of the CdS layer on the CZTS or CZTSe layer. A small amount of n-type CdCu and neutral CdZn would also be formed.

  12. RF Sputtered ZnTe:N as CdS/CdTe Solar Cell Back-Contact Material

    Science.gov (United States)

    Ma, X.

    1999-04-01

    The most frequently used electrical contact to CdTe thin-film polycrystalline solar cells on glass involves the use of copper. However, Cu is known to be a fast diffuser in many semiconductors and is suspected of leading to some deterioration of performance of CdTe solar cells under extreme conditions. In this work we report on the development of a reactively sputtered ZnTe:N back contact on solar cells. Promising low-resistive nitrogen-doped ZnTe films were obtained. Efficiencies up to 10.8 percent were obtained for solar cells fabricated with a ZnTe:N/Au back contact scheme. Comparison of cell performances using ZnTe:N and Cu/Au back-contacts is presented.

  13. The mobility and human oral bioaccessibility of Zn and Pb in urban dusts of Estarreja (N Portugal).

    Science.gov (United States)

    Patinha, C; Reis, A P; Dias, A C; Abduljelil, A A; Noack, Y; Robert, S; Cave, M; Ferreira da Silva, E

    2015-02-01

    Twenty-one samples of urban dust were collected from Estarreja city (Portugal). The main objective of this work was to assess the potential availability of Pb and Zn present dust samples from Estarreja city via the oral ingestion exposure route using a combination of geochemical tests: (a) using sequential extraction to identify the fractionation of the Pb and Zn within the geochemical components that make up the dust and (b) in vitro bioaccessibility (BA) measurements to identify which components are the source(s) of the bioaccessible fraction (Bf). These samples were analysed for their quasi-total contents of Pb and Zn by inductively coupled plasma mass spectrometry, for their element solid-phase distribution using selective sequential extraction method and for the Bfs of these elements using a physiologically based extraction test. The study showed that the concentrations of Zn were higher than Pb, but both are site-specific. The sequential extraction test shows that the exchangeable and acid-soluble phases are important bearing phases for Pb and Zn. The BA test showed that a high proportion of the total concentration is available for absorption into the human body (ranges from 22.5 to 84.1% for Pb and 28.7 to 86.3% for Zn). PMID:25027473

  14. The X-ray response of CdZnTe

    CERN Document Server

    Owens, A; Andersson, H; Gagliardi, T; Krumrey, M; Nenonen, S; Peacock, A; Taylor, I; Troeger, L

    2002-01-01

    We report the results of a series of X-ray measurements on a 3.1 mm sup 2 , 2.5 mm thick CdZnTe detector carried out at the BESSY II and HASYLAB synchrotron radiation facilities. The detector energy response function was found to be linear over the energy range 2.3-100 keV with an average rms non-linearity of 0.6%, consistent with statistics. At room temperature, under full-area illumination, the FWHM energy resolution was 1.6 keV at 5.9 keV rising to 2.9 keV at 59.54 keV. At a reduced detector temperature of -20 deg. C, these fall to 380 and 818 eV FWHM, respectively. Under pencil beam illumination, the measured energy resolution at 2.5 keV was 360 eV FWHM rising to 1558 eV at 100 keV. By best fitting the expected resolution function to the experimental data, we derive a value for the Fano factor of (0.099+-0.02). Cooling the detector to -50 deg. C, resulted in no noticeable difference in DELTA E above 60 keV, but a 40% reduction at energies <10 keV. At 5.9 keV, the measured resolution under full-area ill...

  15. Development of CdZnTe radiation detectors

    Science.gov (United States)

    Bolotnikov, Aleksey; Camarda, Giuseppe; Hossain, Anwar; Kim, Ki Hyun; Yang, Ge; Gul, Rubi; Cui, Yonggang; James, Ralph B.

    2011-08-01

    Cadmium Zinc Telluride (CdZnTe or CZT) is a very attractive material for room-temperature semiconductor detectors because of its wide band-gap and high atomic number. Despite these advantages, CZT still presents some material limitations and poor hole mobility. In the past decade most of the efforts developing CZT detectors focused on designing different electrode configurations, mainly to minimize the deleterious effect due to the poor hole mobility. A few different electrode geometries were designed and fabricated, such as pixelated anodes and Frisch-grid detectors developed at Brookhaven National Lab (BNL). However, crystal defects in CZT materials still limit the yield of detector-grade crystals, and, in general, dominate the detector's performance. In the past few years, our group's research extended to characterizing the CZT materials at the micro-scale, and to correlating crystal defects with the detector's performance. We built a set of unique tools for this purpose, including infrared (IR) transmission microscopy, X-ray micro-scale mapping using synchrotron light source, X-ray transmission- and reflection- topography, current deep level transient spectroscopy (I-DLTS), and photoluminescence measurements. Our most recent work on CZT detectors was directed towards detailing various crystal defects, studying the internal electrical field, and delineating the effects of thermal annealing on improving the material properties. In this paper, we report our most recent results.

  16. Lasing in ZnO and CdS nanowires

    International Nuclear Information System (INIS)

    The development of nanoscaled semiconductor lasers could be the key resolution to the still persistent size mismatch between integrated microelectronic devices and semiconductor optoelectronic devices. Semiconductor nanowires offer an elegant path to the development of nanoscaled lasers as their geometry with two planar end facets naturally combines a fiber-like waveguide with an optical resonator. The possible stimulation of the material's emission processes enables lasing of resonant optical modes. ZnO and CdS nanowires of different aspect ratios have been synthesized via the VLS mechanism and were characterized by SEM, EDX and ensemble PL measurements. Power dependent PL measurements on single nanowires excited with pulsed laser light at 355 nm have been performed between 10 K and room temperature and were set in correlation to the nanowires' respective morphology. Sharp emission lines which show characteristics of Fabry-Perot modes could be observed above a power threshold. The measured power dependencies reveal amplified stimulated emission and lasing at high excitation densities.

  17. CdZnTe array detectors for synchrotron radiation applications

    International Nuclear Information System (INIS)

    An X-ray linear-array detector was fabricated using high-pressure Bridgman-grown CdZnTe. The detector area was 175 x 800 μm and the pitch size was 250 μm. The measured dark current for the test 16-element detector was as low as 0.1 pA at 800 V cm-1 with excellent uniformity. Energy spectra were measured using a 57Co radiation source. Both a small-pixel effect and charge sharing were observed. For the arrays, an average 5.8% full width a half-maximum (FWHM) at the 122 keV photopeak was obtained with a standard deviation of 0.2%. A large-area detector (1 x 1 cm) of the same material before fabrication exhibited a low-energy tail at the photopeak, which limits the photopeak FWHM to 8%, typically due to hole trapping. At energies below 60 keV, charge sharing between elements was observed. The charge sharing was greatly reduced by providing a path to ground for unwanted charges. A prototype readout electronic system for an eight-channel array detector was developed. A readout system intended for a multielement solid-state detector system was also used. The array detector will be used for high-energy diffraction and Compton scattering measurements at the Advanced Photon Source. (au)

  18. The molecular physiology of heavy metal transport in the Zn/Cd hyperaccumulator Thlaspi caerulescens

    OpenAIRE

    Pence, Nicole S.; Larsen, Paul B.; Ebbs, Stephen D.; Letham, Deborah L. D.; Lasat, Mitch M.; Garvin, David F; Eide, David; Kochian, Leon V.

    2000-01-01

    An integrated molecular and physiological investigation of the fundamental mechanisms of heavy metal accumulation was conducted in Thlaspi caerulescens, a Zn/Cd-hyperaccumulating plant species. A heavy metal transporter cDNA, ZNT1, was cloned from T. caerulescens through functional complementation in yeast and was shown to mediate high-affinity Zn2+ uptake as well as low-affinity Cd2+ uptake. It was found that this transporter is expressed at very high levels i...

  19. Raman scattering determination of strain in CdTe/ZnTe superlattices

    OpenAIRE

    Jackson, M K; Miles, R. H.; McGill, T. C.; Faurie, J. P.

    1989-01-01

    The strain configuration in CdTe/ZnTe strained-layer superlattices has been measured by Raman scattering near resonance. The ZnTe-like longitudinal optical phonon energy in the superlattice is significantly shifted from the bulk value to lower energies and the shift increases with increasing superlattice CdTe fraction. The observed shifts agree with calculations of strain shifts based on a free-standing strain distribution.

  20. Metals Accumulation and Leaf Surface Anatomy of Murdannia spectabilis Growing in Zn/Cd Contaminated Soil

    OpenAIRE

    Ladawan Rattanapolsan; Woranan Nakbanpote; Piyaporn Saensouk

    2013-01-01

    Murdannia spectabilis (Kurz) Faden was identified as a Zn/Cd hyperaccumulative plant. Leaf surface anatomy of the plant growing in non-contaminated soil (control) and Zn/Cd contaminated soil,was studied and compared by a light microscopy and scanning electron microscopy combined with Energy-dispersive X-ray spectroscopy(SEM/EDS). The similarities were reticulate cuticle on epidermises, uniform polygonal cell, stomatal arrangement in six surrounding subsidiary cells, and submarginal sclerenchy...

  1. Reduced leakage currents of CdZnTe radiation detectors with HgTe/HgCdTe superlattice contacts

    Science.gov (United States)

    Chang, Y.; Grein, C. H.; Becker, C. R.; Huang, J.; Ghosh, S.; Aqariden, F.; Sivananthan, S.

    2012-10-01

    Room-temperature-operating CdZnTe radiation detectors have high energy resolution, linear energy response and are capable of operating in normal counting and spectroscopic modes, hence are highly desirable for medical diagnosis, nondestructive industrial evaluations, homeland security, counterterrorism inspections and nuclear proliferation detection to ensure national and international nuclear safety. HgTe/HgCdTe superlattices can be designed to selectively transport one carrier species while hindering transport of the other. Specifically, one designs a large carrier effective mass for undesired carriers in the electric field direction, which results in low carrier velocities, and yet a density of states for undesired carrier that is lower than that of a comparable bulk semiconductor, which results in low carrier concentrations, hence a low current density under an electric field. The opposite carrier species can be designed to have a large velocity and high density of states, hence producing a large current density. By employing HgTe/HgCdTe superlattices as contact layers intermediate between CdZnTe absorbers and metal contacts, leakage currents under high electric fields are reduced and improved x-ray and γ-ray detector performance is anticipated. Pixilated CdZnTe radiation detectors arrays were fabricated and characterized to evaluate the effectiveness of HgTe/HgCdTe superlattices in reducing leakage currents. Current-voltage characteristics show that HgTe/HgCdTe superlattice contact layers consistently result in significantly reduced leakage currents relative to detectors with only metal contacts.

  2. “Turn on/off” proton transfer based fluorescent sensor for selective detection of environmentally hazardous metal ions (Zn2+, Pb2+) in aqueous media

    International Nuclear Information System (INIS)

    Sensing ability of fluorescence based chemosensor: Indole-7-carboxaldehyde (I7C) for environmentally hazardous metal ions (Xn+=Zn2+, Pb2+, Co2+, Ni2+, Cu2+, Cd2+, Cr3+, and Fe3+) has been investigated. Based on excited state proton transfer (ESPT) phenomenon, the sensing capability of I7C is verified experimentally (UV–vis, FTIR, NMR) and theoretically (DFT, TD-DFT) in aqueous media. Chemical hardness (η), electrophilicity (ω) and electronic chemical potentials (μ) confirm the selective reactivity of I7C (Nc and Nt conformers) in the presence of metal ions by the formation of (1:1) metal ion: I7C complex (MX, MX⁎). MX, MX⁎ are found to display excellent sensing capability for Zn2+ and Pb2+ ions. “Turn-On” response for Zn2+ is observed through the appearance of a new enhanced fluorescence at ~430 nm. By strong blue emission I7C establishes its strong candidature as “blue emitter”. “Turn-Off” response is observed for Pb2+ through the quenching of the existing fluorescence peak. - Highlights: • Indole-7-carboxaldehyde (I7C) shows “Turn-on” and “Turn-off” sensing for Zn2+ and Pb2+ ions. • I7C forms complex with metal ions (MX⁎). • 27-Fold strong blue fluorescence due to MZn⁎ formation indicates I7C as a good candidature to be used as blue emitter. • Computed (UV–vis absorption/emission, FTIR, NMR) data validate the experimental facts

  3. CdS-ZnSe和CdSe-ZnS量子点的合成和F(o)rster能量转移研究%Synthesis and F(o)rster Resonant Energy Transfer (FRET) Study of Quantum Dots Assembly

    Institute of Scientific and Technical Information of China (English)

    弓亚琼; 詹寰; 张贺楠; 卫增岩; 苏伟

    2013-01-01

    One F(o)rster resonant energy transfer (FRET) donor-acceptor assembly was built from quantum dots (QDs) of type Ⅰ CdSe-ZnS (QD491) and type Ⅲ CdS-ZnSe (QD560) QDs.The assembly was further characterized by steady-state and time-resolved photoluminescence (TRPL) measurements at different donor-to-acceptor ratios.Both photoluminescence quenching and reduction of the exciton lifetime of donor QDs provide concrete evidence of FRET between the type Ⅰ QDs and the type Ⅱ QDs.Because the emission wavelengths of CdS-ZnSe and CdSe-ZnS QDs can be spectrally separated by tuning the size of these QDs,the binary QD assembly of type Ⅰ-type Ⅱ QDs could be an attractive approach for the development of efficient light emitters and bio-sensors.%采用分步合成法成功合成了CdS-ZnSe(Ⅰ型)和CdSe-ZnS(Ⅱ型)核-壳结构量子点.并首次构建了CdS-ZnSe/CdSe-ZnS结构F(o)rster能量转移对.利用吸收光谱(UV-Vis),光致发光谱(PL),时间分辨光致发光谱(TRPL),透射电子显微镜(TEM)对比研究了不同配比的CdS-ZnSe/CdSe-ZnS结构Fö rster能量转移.分析结果表明:在能量转移发生时,CdS-ZnSe荧光强度显著下降,荧光寿命明显缩短,F(o)rster能量转移确实存在于CdS-ZnSe/CdSe-ZnS量子点之间.

  4. Interaction between Cd and Pb in the soil-plant system:a case study of an arid oasis soil-cole system

    Institute of Scientific and Technical Information of China (English)

    ZhuanJun ZHAO; ZhongRen NAN; ZhaoWei WANG; YiMing YANG; Masayuki SHIMIZU

    2014-01-01

    The Hexi Corridor, our study area, is located in Northwest China and is also the most developed area of oasis farming in arid regions of Northwestern China. However, the rapid development of metallurgy and chemical industries in this region poses a great threat to the accumulation of heavy metals in crops. The objectives of this study are (1) to determine the influence of heavy metals on plant growth;(2) to assess the translocation capability of heavy metals in soil-plant system; and (3) to investigate the interaction between heavy metals. Pot experiments were conducted on cole (Brassica campestris L.) grown in the arid oasis soils singly and jointly treated with cad-mium (Cd) and lead (Pb). Nine treatments were applied into the pots. Under the same planting conditions, three scenarios of Cd, Pb and Cd-Pb were designed to compare the interaction between Cd and Pb. The results showed that the response of cole weights to Cd, Pb and Cd-Pb treatments was slight, while Cd and Pb uptakes in cole were more sensitive to the single effects of Cd and Pb concentration in soils from the lower treatment levels. Under the influence of the single Cd, Pb and joint Cd-Pb treatments, Cd concentrations were lower in the cole roots than in the shoots, while for Pb, the results were opposite. Comparison studies revealed that the interaction of Cd and Pb could weaken the cole’s ability to uptake, concentrate and translocate heavy metals in arid oasis soils.

  5. Pb(II)-promoted amide cleavage: mechanistic comparison to a Zn(II) analogue.

    Science.gov (United States)

    Elton, Eric S; Zhang, Tingting; Prabhakar, Rajeev; Arif, Atta M; Berreau, Lisa M

    2013-10-01

    Two new Pb(II) complexes of the amide-appended nitrogen/sulfur epppa (N-((2-ethylthio)ethyl)-N-((6-pivaloylamido-2-pyridyl)methyl)-N-((2-pyridyl)methyl)amine) chelate ligand, [(epppa)Pb(NO3)2] (4-NO3) and [(epppa)Pb(ClO4)2] (4-ClO4), were prepared and characterized. In the solid state, 4-NO3 exhibits κ(5)-epppa chelate ligand coordination as well as the coordination of two bidentate nitrate ions. In acetonitrile, 4-NO3 is a 1:1 electrolyte with a coordinated NO3(-), whereas 4-ClO4 is a 1:2 electrolyte. Treatment of 4-ClO4 with 1 equiv Me4NOH·5H2O in CH3CN:CH3OH (3:5) results in amide methanolysis in a reaction that is akin to that previously reported for the Zn(II) analogue [(epppa)Zn](ClO4)2 (3-ClO4). (1)H NMR kinetic studies of the amide methanolysis reactions of 4-ClO4 and 3-ClO4 as a function of temperature revealed free energies of activation of 21.3 and 24.5 kcal/mol, respectively. The amide methanolysis reactions of 4-ClO4 and 3-ClO4 differ in terms of the effect of the concentration of methanol (saturation kinetics for 4-ClO4; second-order behavior for 3-ClO4), the observation of a small solvent kinetic isotope effect (SKIE) only for the reaction of the Zn(II)-containing 3-ClO4, and the properties of an initial intermediate isolated from each reaction upon treatment with Me4NOH·5H2O. These experimental results, combined with computational studies of the amide methanolysis reaction pathways of 4-ClO4 and 3-ClO4, indicate that the Zn(II)-containing 3-ClO4 initially undergoes amide deprotonation upon treatment with Me4NOH·5H2O. Subsequent amide protonation from coordinated methanol yields a structure containing a coordinated neutral amide and methoxide anion from which amide cleavage can then proceed. The rate-determining step in this pathway is either amide protonation or protonation of the leaving group. The Pb(II)-containing 4-ClO4 instead directly forms a neutral amide-containing, epppa-ligated Pb(II)-OH/Pb(II)-OCH3 equilibrium mixture upon treatment

  6. Development of low background CdZnTe detectors for detection of double beta decays of sup 6 sup 4 Zn

    CERN Document Server

    Watanabe, T; Takahisa, K; Tanikawa, M; Ito, Y

    1999-01-01

    Development of low background CdZnTe detectors is in progress to study neutrino-less double beta decay. The mu tau product (mobility times lifetime) for holes was measured in a set of CdZnTe detectors at various temperatures between +22 deg. C and -40 deg. C in order to investigate charge collection efficiencies for holes. The sensitivity of CdZnTe detectors to neutrino-less beta sup + EC decays of sup 6 sup 4 Zn ( sup 6 sup 4 Zn+EC-> sup 6 sup 4 Ni+beta sup +) is estimated from these data.

  7. Dip coated nanocrystalline CdZnS thin films for solar cell application

    Science.gov (United States)

    Dongre, J. K.; Chaturvedi, Mahim; Patil, Yuvraj; Sharma, Sandhya; Jain, U. K.

    2015-07-01

    Nanocrystalline cadmium sulfide (CdS) and zinc cadmium sulfide (ZnCdS) thin films have been grown via simple and low cost dip coating technique. The prepared films are characterized by X-ray diffraction (XRD), atomic force microscopic (AFM) and UV-VIS spectrophotometer techniques to reveal their structural, morphological and optical properties. XRD shows that both samples grown have zinc blende structure. The grain size is calculated as 6.2 and 8 nm using Scherrer's formula. The band gap value of CdS and CdZnS film is estimated to be 2.58 and 2.69 eV respectively by UV-vis spectroscopy. Photoelectrochemical (PEC) investigations are carried out using cell configuration as n-CdZnS/(1M NaOH + 1M Na2S + 1M S)/C. The photovoltaic output characteristic is used to calculate fill-factor (FF) and solar conversion efficiency (η).

  8. Biosorption of Cd(II) and Zn(II) by nostoc commune: isotherm and kinetics studies

    Energy Technology Data Exchange (ETDEWEB)

    Morsy, Fatthy M. [Faculty of Science, Botany Department, Assiut University, Assiut (Egypt); Hassan, Sedky H.A. [Department of Biological Environment, Kangwon National University, Kangwon-do (Korea, Republic of); Koutb, Mostafa [Faculty of Science, Botany Department, Assiut University, Assiut (Egypt); Umm Al-Qura University, Faculty of Applied Science, Biology Department, Mecca (Saudi Arabia)

    2011-07-15

    In this study, Nostoc commune (cyanobacterium) was used as an inexpensive and efficient biosorbent for Cd(II) and Zn(II) removal from aqueous solutions. The effect of various physicochemical factors on Cd(II) and Zn(II) biosorption such as pH 2.0-7.0, initial metal concentration 0.0-300 mg/L and contact time 0-120 min were studied. Optimum pH for removal of Cd(II) and Zn(II) was 6.0, while the contact time was 30 min at room temperature. The nature of biosorbent and metal ion interaction was evaluated by infrared (IR) technique. IR analysis of bacterial biomass revealed the presence of amino, carboxyl, hydroxyl, and carbonyl groups, which are responsible for biosorption of Cd(II) and Zn (II). The maximum biosorption capacities for Cd(II) and Zn(II) biosorption by N. commune calculated from Langmuir biosorption isotherm were 126.32 and 115.41 mg/g, respectively. The biosorption isotherm for two biosorbents fitted well with Freundlich isotherm than Langmuir model with correlation coefficient (r{sup 2} < 0.99). The biosorption kinetic data were fitted well with the pseudo-second-order kinetic model. Thus, this study indicated that the N. commune is an efficient biosorbent for the removal of Cd(II) and Zn(II) from aqueous solutions. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  9. Optical characterization of ZnS coated CdS nanorods embedded in liquid crystals

    Science.gov (United States)

    Roy, J. S.; Majumder, T. Pal; Dabrowski, R.

    2016-05-01

    The photoluminescence (PL) emission intensity of ZnS coated CdS nanorods, represented by CdS/ZnS system, have been enhanced in presence of liquid crystals (LC) and the enhancement strongly depends on concentration of LC. The highly light scattering liquid crystalline phase causes the enhancement in PL intensity. It is also observed that the PL intensity of CdS nanorods enhances with the coating of ZnS material. This enhancement in PL intensity is ascribed by the fact that the high optical band gap ZnS material prevents the tunneling of the charge carriers from the core CdS nanorods and passivated nonradiative recombination sites which are existed on the core surfaces. Finally, 5 fold enhancements in PL intensity of CdS nanorods have been observed by coating with ZnS material and then embedding in LC. We have also observed the red shift in emission energy band of CdS/ZnS system embedded in LC. This study will provide a possible way to develop smart optoelectronics devices.

  10. Corrosion behaviour of boiler tube materials during combustion of fuels containing Zn and Pb

    Energy Technology Data Exchange (ETDEWEB)

    Bankiewicz, D.

    2012-11-01

    Many power plants burning challenging fuels such as waste-derived fuels experience failures of the superheaters and/or increased waterwall corrosion due to aggressive fuel components already at low temperatures. To minimize corrosion problems in waste-fired boilers, the steam temperature is currently kept at a relatively low level which drastically limits power production efficiency. The elements found in deposits of waste and waste-derived fuels burning boilers that are most frequently associated with high-temperature corrosion are: Cl, S, and there are also indications of Br; alkali metals, mainly K and Na, and heavy metals such as Pb and Zn. The low steam pressure and temperature in waste-fired boilers also influence the temperature of the waterwall steel which is nowadays kept in the range of 300 deg C - 400 deg C. Alkali chloride (KCl, NaCl) induced high-temperature corrosion has not been reported to be particularly relevant at such low material temperatures, but the presence of Zn and Pb compounds in the deposits have been found to induce corrosion already in the 300 deg C - 400 deg C temperature range. Upon combustion, Zn and Pb may react with Cl and S to form chlorides and sulphates in the flue gases. These specific heavy metal compounds are of special concern due to the formation of low melting salt mixtures. These low melting, gaseous or solid compounds are entrained in the flue gases and may stick or condense on colder surfaces of furnace walls and superheaters when passing the convective parts of the boiler, thereby forming an aggressive deposit. A deposit rich in heavy metal (Zn, Pb) chlorides and sulphates increases the risk for corrosion which can be additionally enhanced by the presence of a molten phase. The objective of this study was to obtain better insight into high-temperature corrosion induced by Zn and Pb and to estimate the behaviour and resistance of some boiler superheater and waterwall materials in environments rich in those heavy metals

  11. Preparation of ZnO/CdS/BC Photocatalyst Hybrid Fiber and Research of Its Photocatalytic Properties

    Directory of Open Access Journals (Sweden)

    Beibei Dai

    2015-01-01

    Full Text Available An environment-friendly biomaterial bacterial cellulose (BC is introduced to substitute general organic polymers to assist the preparation of ZnO/CdS/BC photocatalyst hybrid nanofiber through coprecipitation method under the low-temperature condition. The XRD, XPS, and SEM results show that high load of ZnO/CdS/BC ternary hybrid fiber can be produced. TGA curves scan shows that ZnO/CdS/BC hybrid fiber has better thermal properties than bacterial cellulose. The UV-Vis spectra of the ZnO/CdS/BC hybrid nanofiber (0, 10, 20, and 50 wt%, resp. show that photocatalytic activities of ZnO/CdS/BC are influenced by the added amount of CdS. The degradation curve of methyl shows that ZnO/CdS/BC nanohybrid fibers exhibit excellent photocatalytic efficiency.

  12. Fluorescence behavior of glutathione capped CdTe@ZnS quantum dots chemically coordinated to zinc octacarboxy phthalocyanines

    International Nuclear Information System (INIS)

    Core–shell CdTe@ZnS quantum dots capped with glutathione (CdTe@ZnS–GSH) were covalently linked to zinc octacarboxy phthalocyanine (ZnPc(COOH)8). The conjugate was characterized by UV/Vis, infrared and X-Ray photoelectron spectroscopies as well as transmission electron and atomic force microscopies. The fluorescence quantum yields of the core CdTe capped with thioglycolic acid increased upon formation of the core-shell. Upon conjugation with ZnPc(COOH)8, the fluorescence quantum yield of CdTe@ZnS–GSH decreased due to energy transfer from the latter to the Pc. The average fluorescence lifetime of the CdTe@ZnS–GSH QD also decreased upon conjugation from 26.2 to 13.3 ns. -- Graphical Abstract: CdTe@ZnS quantum dots capped with glutathione (CdTe@ZnS-GSH) and covalently linked to zinc octacarboxy phthalocyanine (ZnPc(COOH)8), showed decreased fluorescence quantum yield and lifetime of the CdTe@ZnS-GSH following conjugation due to energy transfer. Highlights: ► CdTe@ZnS quantum dots capped with glutathione were synthesized. ► The quantum dots were chemically linked to zinc octacarboxy phthalocyanine. ► The fluorescence quantum yields of the quantum dots decreased on conjugation. ► Fluorescence lifetimes also decreased due to energy transfer

  13. Ion beam induced charge imaging of charge transport in CdTe and CdZnTe

    International Nuclear Information System (INIS)

    Ion beam induced charge (IBIC) imaging is a powerful technique for quantitative mapping of the charge transport performance of wide bandgap semiconductor materials. In this paper we present results from a study of electron and hole mobility-lifetime product and drift mobility in CdTe:Cl and CdZnTe, which are semiconductor materials used for radiation detector applications. IBIC imaging has been used to produce mobility-lifetime product maps in CdTe:Cl and CdZnTe, revealing the influence of extended defects and tellurium inclusions and assessing the large area response uniformity of the materials. The recent extension of this method in the form of digital time-resolved IBIC is also discussed and time of flight maps are presented which give quantitative images of electron and hole drift mobility

  14. The heat capacity of zinc and cadmium chalcogenides (ZnTe, CdSe, and CdTe)

    International Nuclear Information System (INIS)

    Heat capacity of zinc telluride, cadmium selenide and telluride are measured by the calorimetry method at 370-640 K (ZnTe) and 500-760 K (CdSe, CdTe). Analysis of literature data on heat capacity of the above-mentioned solid solutions at temperatures in excess of 298 K is carried out. On the basis of the results obtained and most dependable literature data on heat capacity of the compounds for temperature ranges of 220-1500 K (ZnTe, CdSe) and 220-1300 K (CdTe) new equations of heat capacity temperature dependence are suggested and thermodynamic functions of the compounds are calculated

  15. Synthesis and spectroscopic study of high quality alloy CdZn1-S nanocrystals

    Indian Academy of Sciences (India)

    Suparna Sadhu; Amitava Patra

    2008-11-01

    In the present study, we report the synthesis of high quality CdZn1-S nanocrystals alloy at 150°C with changing the composition. The shifting of absorption and emission peak in shorter wavelength is obtained with increasing the mole fraction of zinc. The quantum yield (QY) value decreases with increasing the Cd mole fraction and the values are 0.08, 0.13 and 0.40 for Cd0.62Zn0.38S, Cd0.52Zn0.48S and Cd0.31Zn0.69S nanocrystals, respectively after 120 min of reaction. However, the full width at halfmaximum (fwhm) values are 45, 34 and 28 nm and the corresponding quantum yield (QY) values are 0.52, 0.17 and 0.13 for 0.5 mM, 1.5 mM and 3 mM of initial S concentrations, respectively. It is interesting to note that the radiative decay time is dominating with increasing the Cd content. Analysis suggests that the decay dynamics depends on the composition of CdZn1-S nanocrystals.

  16. Photoluminescence of localized excitons in ZnCdO thin films grown by molecular beam epitaxy

    Science.gov (United States)

    Wu, T. Y.; Huang, Y. S.; Hu, S. Y.; Lee, Y. C.; Tiong, K. K.; Chang, C. C.; Shen, J. L.; Chou, W. C.

    2016-07-01

    We have investigated the luminescence characteristics of Zn1-xCdxO thin films with different Cd contents grown by molecular beam epitaxy system. The temperature-dependent photoluminescence (PL) and excitation power-dependent PL spectra were measured to clarify the luminescence mechanisms of the Zn1-xCdxO thin films. The peak energy of the Zn1-xCdxO thin films with increasing the Cd concentration is observed as redshift and can be fitted by the quadratic function of alloy content. The broadened full-width at half-maximum (FWHM) estimated from the 15 K PL spectra as a function of Cd content shows a larger deviation between the experimental values and theoretical curve, which indicates that experimental FWHM values are affected not only by alloy compositional disorder but also by localized excitons occupying states in the tail of the density of states. The Urbach energy determined from an analysis of the lineshape of the low-energy side of the PL spectrum and the degree of localization effect estimated from the temperature-induced S-shaped PL peak position described an increasing mean exciton-localization effects in ZnCdO films with increasing the Cd content. In addition, the PL intensity and peak position as a function of excitation power are carried out to clarify the types of radiative recombination and the effects of localized exciton in the ZnCdO films with different Cd contents.

  17. Pathways toward higher performance CdS/CdTe devices: Te exposure of CdTe surface before ZnTe:Cu/Ti contacting

    International Nuclear Information System (INIS)

    Many studies of thin-film CdS/CdTe photovoltaic devices have suggested that performance may be improved by reducing recombination due to Te-vacancy (VTe), Te antisite (TeCd), or Te-interstitial (Tei) defects. Although formation of these intrinsic defects is likely influenced by CdTe deposition parameters, it may be also coupled to the formation of beneficial cadmium vacancy (VCd) defects. In this study, we expose the CdTe surface to Te vapor prior to ZnTe:Cu/Ti contact-interface formation with the goal of reducing VTe without significantly reducing VCd. Initial results show that when this modified contact is used on a CdCl2-treated CdS/CdTe device, poorer device performance results. This suggests two things: First, the amount of free-Te available during contact formation (either from chemical etching or CuxTe or ZnTe deposition) may be a more important parameter to device performance than previously appreciated. Second, if processes have been used to reduce the effect of VTe (e.g., oxygen and chlorine additions), adding even a small amount of Te may produce detrimental defects. - Highlights: ► Te exposure of CdS/CdTe back contact reduces device performance. ► Field strength and minority carrier lifetime reduced. ► Calculations suggest formation of Te on Cd antisite defect

  18. Study of the spectrometric performances of monolithic CdTe CdZnTe gamma ray detectors

    OpenAIRE

    Gros D'Aillon, Eric

    2005-01-01

    Pixelated monolithic CdTe / CdZnTe semiconductor gamma ray detectors are brought to replace scintillation detectors for medical applications, notably for single photon emission computed tomography (SPECT). In addition to compactness, they present better spectrometric performances: energy resolution, detection efficiency, and spatial resolution. Moreover, the photons depth of interaction in the crystal can be measured. This work aimed in studying experimentally and by simulation the correlatio...

  19. Metals Accumulation and Leaf Surface Anatomy of Murdannia spectabilis Growing in Zn/Cd Contaminated Soil

    Directory of Open Access Journals (Sweden)

    Ladawan Rattanapolsan

    2013-07-01

    Full Text Available Murdannia spectabilis (Kurz Faden was identified as a Zn/Cd hyperaccumulative plant. Leaf surface anatomy of the plant growing in non-contaminated soil (control and Zn/Cd contaminated soil,was studied and compared by a light microscopy and scanning electron microscopy combined with Energy-dispersive X-ray spectroscopy(SEM/EDS. The similarities were reticulate cuticle on epidermises, uniform polygonal cell, stomatal arrangement in six surrounding subsidiary cells, and submarginal sclerenchyma. The dissimilarities were uniserate trichomes spreading on both adaxial and abaxial epidermis of the plants growing in non-contaminated soil, whereas the uniserate trichomes were only on the submarginal-adaxial epidermis of the control plants. The trichomes on leaves of the plants growing in non-contaminated soil were found to have both uniseriate non-glandular and uniseriate glandular trichomes;whereas, leaves of the plants growing in the contaminated soil were merely non-glandular trichomes. The different shape and location of trichomes, the number of stomata and trichome indicated the effect of Zn and Cd on M. spectabilis. The higher percentages of Zn and Cd in the vascular bundle than in the cross section and epidermis areas showed both solutes could move along each route, with diffusion through the symplast and apoplast. The increase of Ca in M. spectabilis growing in Zn/Cd contaminated soil corresponded to the Zn and Cd distributed in the leaves. Zn K-edge and S K-edge XANES spectra proposed that Zn2+ ions were accumulated and/or adsorbed on the epidermis of the tuber, and then absorbed into the root and transport to the xylem. The double peaks of Zn-cysteine in the leaf samples proposed the metal sequestration was by sulphur proteins.

  20. Probing the sensitive and selective luminescent detection of peroxynitrite using thiol-capped CdTe and CdTe-ZnS quantum dots

    International Nuclear Information System (INIS)

    CdTe and CdTe-ZnS quantum dots (QDs) capped with 3-mercaptopropionic acid (MPA), thioglycolic acid (TGA), or glutathione (GSH) have been employed for the first time as luminescent probes for the sensitive and selective detection of peroxynitrite (ONOO−) in aqueous solution. The sensitivity of the proposed probe followed the order: MPA–TGA–CdTe-ZnS>GSH–TGA–CdTe-ZnS>MPA–CdTe QDs. The varying degree of quenching is elucidated based on the QD–thiolate bond of CdTe-ZnS being more sensitive to oxidation from ONOO− than CdTe. The selectivity of the probe in the presence of co-existing species followed the order: GSH–TGA–CdTe-ZnS>MPA–TGA–CdTe-ZnS>MPA–CdTe QDs. QDs capped with MPA showed less selectivity for ONOO− than GSH. The best limit of detection (LOD) of 12.6 nM was obtained for MPA–TGA–CdTe-ZnS QDs. Time-resolved fluorescence measurements indicated that the interaction between ONOO− and the QDs is static in nature. - Graphical abstract: CdTe and CdTe-ZnS quantum dots capped with 3-mercaptopropionic acid or glutathione are employed for the detection of peroxynitrite in aqueous solution, with glutathione capped quantum dots showing the best selectivity and core–shell quantum dots showing better sensitivity than core quantum dots. Highlights: ► CdTe and CdTe-ZnS quantum dots were employed for the detection of peroxynitrite. ► The best limit of detection of 12.6 nM was obtained. ► Quantum dots capped with mercaptopropionic acid were less selective for ONOO− than glutathione. ► Interaction between peroxynitrite and the quantum dots is static in nature.

  1. Varying effect of biochar on Cd, Pb and As mobility in a multi-metal contaminated paddy soil.

    Science.gov (United States)

    Yin, Daixia; Wang, Xin; Chen, Can; Peng, Bo; Tan, Changyin; Li, Hailong

    2016-06-01

    Cd, Pb and As stand as the most prominent contaminants prevailing in Chinese soils. In the present study, biochars derived from water hyacinth (BCW) and rice straw (BCR) were investigated regarding their applicability and durability in soil Cd, Pb, and As immobilization under acid precipitation. Total Cd, Pb, and As in both BCs were below the maximum allowed threshold according to biochar toxicity standard recommended by International Biochar Initiative. To evaluate BCs effect on Cd, Pb, As bioavailability and mobility, CaCl2, KH2PO4 and SPLP extractions were firstly carried out. In neutral extraction with CaCl2 and KH2PO4, significantly reduced Cd/Pb concentrations in CaCl2 extract along with elevated KH2PO4-extractable As were recorded with either BC at 2% or 5%. In SPLP with simulated acid rainwater as extractant, comparable Cd, Pb and As levels were determined in SPLP extract with 2% BCW, while slight to significant increase in SPLP-Cd, Pb or As was recorded with other treatments. Longer-term leaching column test further confirmed the high durability of 2% BCW in Cd immobilization under continuous acid exposure. In parallel, little increase in As concentrations in eluate was determined with 2% BCW compared to no-biochar control, indicating a lowered risk of As mobilization with acid input. However, remarkably higher Pb in leachate from both BCW-only control and 2% BCW-amended soils were noticed at the initial stage of acid leaching, indicating a higher acid-solubility of Pb minerals in BCW (most probably PbO) than in tested soil (PbO2, PbAs2O6). Taken together, BCW exhibited important potential for soil Cd sequestration with little effect on As mobilization under acid precipitation. But it may simultaneously load highly acid-soluble Pb minerals into soils, resulting in elevated Pb mobility upon acid exposure. Therefore, more stringent threshold for Pb content in biochar need to be put forward to secure biochar application in soils subject to anthropogenic

  2. Spectral analysis of Cu(2+): B(2)O(3)--ZnO--PbO glasses.

    Science.gov (United States)

    Lakshminarayana, G; Buddhudu, S

    2005-11-01

    A new series of heavy metal oxide (PbO) based zinc borate glasses in the chemical composition of (95-x)B(2)O(3)-5ZnO-xPbO (x=10, 15, 20, 25, 30, 35, 40, 45 and 50 mol%) have been prepared to verify their UV filtering performance. Both direct and indirect optical band gaps (E(opt)) have been evaluated for these glasses. For a reference glass of 45B(2)O(3)-5ZnO-50PbO, refractive indices at different wavelengths are measured and found the results satisfactorily correlated with the theoretical data upon the computation of Cauchy's constants of A=1.766029949, B=159531.024 nm(2) and C=-1.078 x 10(10) nm(4). Measurements concerning X-ray diffraction (XRD), FT-IR, differential scanning colorimeter (DSC) profiles have been carried out for this glass. The FT-IR profile has revealed that the glass has both BO(3) and BO(4) units. From DSC thermogram, glass transition temperature (T(g)), crystallization temperature (T(c)) and melting temperature (T(m)) have been located and from them, other related parameters of the glass have also been calculated. Visible absorption spectra of 45B(2)O(3)-5ZnO-(50-x)PbO-xCuO (x=0. 1, 0.2, 0.5 and 1.0 mol%) have revealed two absorption bands at around 400 nm ((2)B(1g)-->(2)E(g)) and 780 nm ((2)B(1g)-->(2)B(2g)) of Cu(2+) ions, respectively. Emission bands at 422 and 512 nm are found for the 1 mol % CuO doped glass with excitations at 306 and 332 nm. PMID:16257737

  3. Optical properties of 60B2O3–(40–)PbO–MCl2 and 50B2O3–(50–) PbO–MCl2 (M = Pb, Cd) glasses

    Indian Academy of Sciences (India)

    Shajo Sebastian; M Abdul Khadar

    2004-04-01

    Optical absorption and transmittance spectra of 60B2O3–(40–)PbO–MCl2 and 50B2O3–(50–) PbO–MCl2 (M = Pb, Cd) (10 ≤ ≤ 20) glasses of varying composition were recorded in the UV-visible region. Various optical parameters such as optical energy gap (opt), Urbach energy (e), refractive index (0), optical dielectric constant (∝), and ratio of carrier concentration to the effective mass (/*) were determined. The variation of optical energy gap with increase in the concentration of PbCl2 or CdCl2 is discussed.

  4. Dual emission in asymmetric "giant" PbS/CdS/CdS core/shell/shell quantum dots.

    Science.gov (United States)

    Zhao, Haiguang; Sirigu, Gianluca; Parisini, Andrea; Camellini, Andrea; Nicotra, Giuseppe; Rosei, Federico; Morandi, Vittorio; Zavelani-Rossi, Margherita; Vomiero, Alberto

    2016-02-21

    Semiconducting nanocrystals optically active in the infrared region of the electromagnetic spectrum enable exciting avenues in fundamental research and novel applications compatible with the infrared transparency windows of biosystems such as chemical and biological optical sensing, including nanoscale thermometry. In this context, quantum dots (QDs) with double color emission may represent ultra-accurate and self-calibrating nanosystems. We present the synthesis of giant core/shell/shell asymmetric QDs having a PbS/CdS zinc blende (Zb)/CdS wurtzite (Wz) structure with double color emission close to the near-infrared (NIR) region. We show that the double emission depends on the excitation condition and analyze the electron-hole distribution responsible for the independent and simultaneous radiative exciton recombination in the PbS core and in the CdS Wz shell, respectively. These results highlight the importance of the driving force leading to preferential crystal growth in asymmetric QDs, and provide a pathway for the rational control of the synthesis of double color emitting giant QDs, leading to the effective exploitation of visible/NIR transparency windows. PMID:26837955

  5. Impaired leaf CO2 diffusion mediates Cd-induced inhibition of photosynthesis in the Zn/Cd hyperaccumulator Picris divaricata.

    Science.gov (United States)

    Tang, Lu; Ying, Rong-Rong; Jiang, Dan; Zeng, Xiao-Wen; Morel, Jean-Louis; Tang, Ye-Tao; Qiu, Rong-Liang

    2013-12-01

    Mechanisms of cadmium (Cd)-induced inhibition of photosynthesis in the Zn/Cd hyperaccumulator Picris divaricata were investigated using photosynthesis limitation analysis. P. divaricata seedlings were grown in nutrient solution containing 0, 5, 10, 25, 50, or 75 μM Cd for 2 weeks. Total limitations to photosynthesis (TL) increased from 0% at 5 μM Cd to 68.8% at 75 μM Cd. CO2 diffusional limitation (DL) made the largest contribution to TL, accounting for 93-98% of TL in the three highest Cd treatments, compared to just 2-7% of TL attributable to biochemical limitation (BL). Microscopic imaging revealed significantly decreased stomatal density and mesophyll thickness in the three highest Cd treatments. Chlorophyll fluorescence parameters related to photosynthetic biochemistry (Fv/Fm, NPQ, ΦPSII, and qP) were not significantly decreased by increased Cd supply. Our results suggest that increased DL in leaves is the main cause of Cd-induced inhibition of photosynthesis in P. divaricata, possibly due to suppressed function of mesophyll and stomata. Analysis of chlorophyll fluorescence showed that Cd supply had little effect on photochemistry parameters, suggesting that the PSII reaction centers are not a main target of Cd inhibition of photosynthesis in P. divaricata. PMID:24077231

  6. The effect of semiconducting CdSe and ZnSe nanoparticles on the fluorescence of Sm3+ in lead borate glasses

    Science.gov (United States)

    Mallur, Saisudha; Fatokun, Stephen; Babu, P. K.

    2015-03-01

    We studied the fluorescence spectra of Sm3+ doped lead borate glasses containing zinc selenide (ZnSe) and cadmium selenide (CdSe) nanoparticles with the following compositions (x PbO: 96.5-x B2O3:0.5 Sm2O3:3ZnSe/CdSe, x =36.5 and 56.5 mol%). These glass samples are prepared using the melt-quenching technique. Each sample is annealed just below the glass transition temperature at 400°C for 3 hrs and 6 hrs. We have chosen PbO-B2O3 glasses to incorporate Sm3+ ions because they have large glass forming region, high refractive index, and good physical and thermal stability. Fluorescence spectra of these samples are obtained with the excitation wavelength at 477 nm. Four fluorescence transitions are observed at 563 nm, 598 nm, 646 nm and 708 nm. The transition at 646 nm is found to be a hypersensitive transition that strongly depends on the covalency of the Sm-O bond and the asymmetry of the crystal field at Sm site. The 646 nm/598 nm fluorescence intensity ratio has been studied for different annealing times and PbO concentration for both ZnSe and CdSe samples. The presence of CdSe nanoparticles is seen to produce the greatest influence on the fluorescence intensity ratio. This could be due to the size of the CdSe nanoparticles and covalency of the Sm-O bond.

  7. Cd{sub 1−x}Zn{sub x}S thin films with low Zn content obtained by an ammonia-free chemical bath deposition process

    Energy Technology Data Exchange (ETDEWEB)

    Carreón-Moncada, I. [Centro de Investigación y de Estudios Avanzados del IPN, Unidad Saltillo, Av. Industria Metalúrgica 1062, CP. 25900, Ramos Arizpe, Coah., México (Mexico); González, L.A., E-mail: luis.gonzalez@cinvestav.edu.mx [Centro de Investigación y de Estudios Avanzados del IPN, Unidad Saltillo, Av. Industria Metalúrgica 1062, CP. 25900, Ramos Arizpe, Coah., México (Mexico); Pech-Canul, M.I. [Centro de Investigación y de Estudios Avanzados del IPN, Unidad Saltillo, Av. Industria Metalúrgica 1062, CP. 25900, Ramos Arizpe, Coah., México (Mexico); Ramírez-Bon, R. [Centro de Investigación y de Estudios Avanzados del IPN, Unidad Querétaro, Apartado Postal 1-798, CP. 76001 Querétaro, Qro., México (Mexico)

    2013-12-02

    Cd{sub 1−x}Zn{sub x}S films with low Zn content were obtained on glass substrates by an ammonia-free chemical bath deposition process. Alkaline reaction solutions were prepared using cadmium chloride, zinc chloride, sodium citrate, thiourea and potassium hydroxide. As a result of varying the mixture ratio between Cd and Zn precursors, microstructural studies from X-ray diffraction reveal that the resulting films have hexagonal, wurzite type, crystalline structure with changes in the preferential growth orientation. Important changes on the surface morphology and thickness of the Cd{sub 1−x}Zn{sub x}S films were also observed as effects of adding Zn to the CdS lattice. Optical studies show that Cd{sub 1−x}Zn{sub x}S thin films with energy band gaps in the range from 2.48 to 2.65 eV were obtained. - Highlights: • Cd{sub 1−x}Zn{sub x}S layers were grown on glass by ammonia-free chemical bath deposition • Films with low Zn content were obtained using reaction solutions with pH11.5 • Zn addition produced changes on the orientation growth and morphology of the films • Cd{sub 1−x}Zn{sub x}S films have energy band gap values from 2.48 to 2.65 eV.

  8. Distribution, bioavailability, and potential ecological risk of Cu, Pb, and Zn in soil in a potential groundwater source area.

    Science.gov (United States)

    Teng, Yanguo; Feng, Dan; Wu, Jin; Zuo, Rui; Song, Liuting; Wang, Jinsheng

    2015-05-01

    In this study, we examined three horizontal and vertical soil profiles along a sewage drainage ditch in order to determine the spatial distribution of Cu, Pb, and Zn in soils and to assess the bioavailability and potential ecological risks associated with these metals in a potential groundwater source area. Results showed that the concentrations of Cu, Pb, and Zn were approximately at background level, suggesting that human activities (industrial and agricultural pollution) had a negligible influence on these metals in soil, and that the concentrations reflected the natural background levels in the study area. Cu, Pb, and Zn concentrations were slightly higher in topsoil (0-20 cm) than deeper in the soil profile. Using a modified BCR sequential extraction method to evaluate the mobility and bioavailability of metals showed that the potential bioavailability sequence of Cu, Pb, and Zn at three depths in the soil profile was in the order Cu ≈ Pb < Zn. The potential ecological risk from the metals was evaluated using risk assessment code, and the results suggest that Cu and Zn pose no or low risk, while there is a low or medium risk from Pb. Results from groundwater monitoring showed that the groundwater was not polluted by leaching from soil. PMID:25910722

  9. Preliminary Performance of CdZnTe Imaging Detector Prototypes

    Science.gov (United States)

    Ramsey, B.; Sharma, D. P.; Meisner, J.; Gostilo, V.; Ivanov, V.; Loupilov, A.; Sokolov, A.; Sipila, H.

    1999-01-01

    The promise of good energy and spatial resolution coupled with high efficiency and near-room-temperature operation has fuelled a large International effort to develop Cadmium-Zinc-Telluride (CdZnTe) for the hard-x-ray region. We present here preliminary results from our development of small-pixel imaging arrays fabricated on 5x5x1-mm and 5x5x2-mm spectroscopy and discriminator-grade material. Each array has 16 (4x4) 0.65-mm gold readout pads on a 0.75-mm pitch, with each pad connected to a discrete preamplifier via a pulse-welded gold wire. Each array is mounted on a 3-stage Peltier cooler and housed in an ion-pump-evacuated housing which also contains a hybrid micro-assembly for the 16 channels of electronics. We have investigated the energy resolution and approximate photopeak efficiency for each pixel at several energies and have used an ultra-fine beam x-ray generator to probe the performance at the pixel boundaries. Both arrays gave similar results, and at an optimum temperature of -20 C we achieved between 2 and 3% FWHM energy resolution at 60 keV and around 15% at 5.9 keV. We found that all the charge was contained within 1 pixel until very close to the pixels edge, where it would start to be shared with its neighbor. Even between pixels, all the charge would be appropriately shared with no apparently loss of efficiency or resolution. Full details of these measurements will be presented, together with their implications for future imaging-spectroscopy applications.

  10. Pb and Sr isotope and geochemical data from the Pb-Zn deposit Bleiberg (Austria): constraints on the age of mineralization

    International Nuclear Information System (INIS)

    The timing of Zn-Pb mineralization hosted by early dolomitized lagoonal limestones (Crest facies) at Bleiberg (Carinthia, Austria) has been constrained using Sr-isotopes. This late stage Zn-Pb mineralization is a special feature of the Bleiberg deposit. Samples of the mineralized Crest facies are characterized by higher concentrations of minor and trace elements (except Ba and Sr) compared to samples from the weakly mineralized Wetterstein limestone of the lagoonal facies. The samples from the Crest facies indicate that a fluid with a minimum 87Sr/86Sr ratio of 0.7083 reacted at 210 ± 30 Ma with carbonate rocks having 87Sr/86Sr ratios of approximately 0.7077 during a late stage of ore formation. The 87Sr/86Sr ratios correlate with the Mn and Cl concentrations. Lead isotope data of whole rock samples of Bleiberg yielded an isochron age of 180 ± 40 Ma. They furthermore confirm the presence of two types of common lead; an isotopically distinct ore lead component is present within and close to the ore bodies. The other common Pb component is present in host rocks and in gangue minerals and is distinguished from the ore lead by lower 207Pb/204Pb and 208Pb/204Pb ratios. The Sr and the Pb ages are consistent with geological evidence indicating a Triassic age of Pb-Zn mineralization and support genetic models emphasizing the role of bacteriogenic sulfate reduction at low temperatures prior to subsidence and burial. Elevated 87Sr/86Sr values (>0.7080) of gangue minerals indicate an epigenetic origin of strontium. Our results are consistent with a genetic model postulating formation of the ore-bearing hydrothermal fluids 'at depth' where they leached lead from pre-upper carboniferous basement rocks. (author)

  11. Effect of ZnO films on CdTe solar cells

    Institute of Scientific and Technical Information of China (English)

    Liu Tingliang; He Xulin; Zhang Jingquan; Feng Lianghuan; Wu Lili; Li Wei; Zeng Guanggen; Li Bing

    2012-01-01

    The ZnO high resistivity transparent (HRT) layers were prepared by DC magnetron sputtering on the 1mm borosilicate glass with 150 nm 1TO coating.The structural,optical and electrical properties of the as-deposited films were investigated by XRD,UV/Vis spectroscopy and four-probe technology.The interface characters of the ITO/ZnO and ZnO/CdS systems were studied by ultraviolet photoelectron spectroscopy (UPS) and X-ray photoelectron spectroscopy (XPS) depth profiling tests.The results show that ZnO has good optical and electrical properties.The insertion of the ZnO films decreases the energy barrier between ITO and CdS films.The energy conversion efficiency and quantum efficiency were found to be 12.77% (8.9%) and > 90% (79%) with or (without)ZnO films of CdTe solar cells.Furthermore,the effect of thickness,mobility and carrier density of ZnO films on CdTe solar cells was analyzed by AMPD-1D.

  12. Effect of ZnO films on CdTe solar cells

    International Nuclear Information System (INIS)

    The ZnO high resistivity transparent (HRT) layers were prepared by DC magnetron sputtering on the 1 mm borosilicate glass with 150 nm ITO coating. The structural, optical and electrical properties of the as-deposited films were investigated by XRD, UV/Vis spectroscopy and four-probe technology. The interface characters of the ITO/ZnO and ZnO/CdS systems were studied by ultraviolet photoelectron spectroscopy (UPS) and X-ray photoelectron spectroscopy (XPS) depth profiling tests. The results show that ZnO has good optical and electrical properties. The insertion of the ZnO films decreases the energy barrier between ITO and CdS films. The energy conversion efficiency and quantum efficiency were found to be 12.77% (8.9%) and > 90% (79%) with or (without) ZnO films of CdTe solar cells. Furthermore, the effect of thickness, mobility and carrier density of ZnO films on CdTe solar cells was analyzed by AMPD-1D. (semiconductor materials)

  13. Phytoextraction of Cd and Zn as single or mixed pollutants from soil by rape (Brassica napus).

    Science.gov (United States)

    Cojocaru, Paula; Gusiatin, Zygmunt Mariusz; Cretescu, Igor

    2016-06-01

    This paper analyses the capacity of the rape (Brassica napus) to extract Cd and Zn from the soil and the effect of these metals on the morphometric parameters of the plant (length, weight, surface area, fractal dimension of leaves). Rape plants were mostly affected by the combined toxicity of the Cd and Zn mixture that caused a significant reduction in the rate of seed germination, the plant biomass quantity and the fractal dimension. In the case of Cd soil pollution, the bioaccumulation factor (BAF), bioaccumulation coefficient (BAC) as well as the heavy metal root-to-stalk translocation factor (TF) were determined. The results showed that B. napus had a great potential as a cadmium hyperaccumulator but not as an accumulator of Zn or Cd + Zn mixture. The efficiency of phytoextraction rape was 0.8-1.22 % for a soil heavily polluted with cadmium. PMID:26884243

  14. Bioaccessibility of Cd and Pb in tailings from a zinc smelting in Brazil: implications for human health.

    Science.gov (United States)

    Ono, F B; Penido, E S; Tappero, R; Sparks, D; Guilherme, L R G

    2016-10-01

    Soils and wastes enriched with heavy metals may present ecological and human health risks. A considerable number of mining areas exist in Brazil, where high levels of metals have been found. However, studies of bioaccessibility of metals in soils/tailings from these areas are scarce, despite their potential informational contribution concerning exposure risks of residents near these areas. This study evaluated tailings collected from four sites of a zinc smelting area located in Brazil with aims to: (1) evaluate the presence of metals of potential concern; (2) investigate Cd and Pb bioaccessibility; and (3) determine the desorption kinetics of Cd and Pb. High concentrations of total Cd and Pb (up to 1743 mg Cd kg(-1) and 8675 mg Pb kg(-1)) and great variability were found in the tailings, indicating the importance of adequate planning for their final disposal, in order to avoid contamination in the surrounding environment. Cadmium and Pb bioaccessibility percentages in the intestinal phase were less than 47 and 4 %, respectively, which represents significant fractions not available for absorption in the intestinal tract. However, this material has to be monitored since its bioaccessibility may increase with eventual physicochemical changes, releasing Cd and Pb. Desorption kinetics experiments revealed that Pb in the samples remained in less labile fractions, whereas Cd was found in more labile fractions, which is in accordance with the bioaccessibility results. PMID:26493831

  15. DETERMINAÇÃO DE Cd E Pb EM AMOSTRAS DE GOMA XANTANA POR GF AAS

    Directory of Open Access Journals (Sweden)

    Alexander O. de Souza

    2015-02-01

    Full Text Available This paper describes the evaluation of a method for determination of Cd and Pb in xanthan gum samples by Graphite Furnace Atomic Absorption Spectrometry (GF AAS using NH4H2PO4 as the chemical modifier. The sample preparation was performed using a reflux system adapted in the digestion tubes. With this system it was possible to increase the temperature of the digester block above the boiling point of the reaction medium, preventing loss of analyte and excessive evaporation of acids during heating. Samples were digested with HNO3 for 3 h in a digester block at 220 ºC. The limits of detection for Cd and Pb were 2.2 and 33.8 ng g-1, respectively. The RSDs for both analytes were, on average, lower than 5.0% and accuracy was verified by recovery tests, yielding values in the 83-100% range.

  16. Use of flue gas desulfurization gypsum for leaching Cd and Pb in reclaimed tidal flat soil.

    Science.gov (United States)

    Yang, Ping; Li, Xian; Tong, Ze-Jun; Li, Qu-Sheng; He, Bao-Yan; Wang, Li-Li; Guo, Shi-Hong; Xu, Zhi-Min

    2016-04-01

    A soil column leaching experiment was conducted to eliminate heavy metals from reclaimed tidal flat soil. Flue gas desulfurization (FGD) gypsum was used for leaching. The highest removal rates of Cd and Pb in the upper soil layers (0-30 cm) were 52.7 and 30.5 %, respectively. Most of the exchangeable and carbonate-bound Cd and Pb were removed. The optimum FGD gypsum application rate was 7.05 kg·m(-2), and the optimum leaching water amount for the application was 217.74 L·m(-2). The application of FGD gypsum (two times) and the extension of the leaching interval time to 20 days increased the heavy metal removal rate in the upper soil layers. The heavy metals desorbed from the upper soil layers were re-adsorbed and fixed in the 30-70 cm soil layers. PMID:26758303

  17. The Liquid-Liquid Extraction of Toxic Metals (Cd, Hg and Pb by Calixarenes

    Directory of Open Access Journals (Sweden)

    D. Max Roundhill

    2009-12-01

    Full Text Available Toxic metals (Cd, Hg and Pb are mostly present in the environment due to natural phenomenon and human activities as well. Exposure of these non-essential elements in the environment causes severe effects. They are known to cause problems in humans as well as in aquatic life. In this work, we demonstrate various studies regarding liquid-liquid extraction of selected ions with different functionalized calixarenes. This review article briefly discusses several molecular designs of calixarenes for divalent ion (Cd2+, Hg2+ and Pb2+ recognition; as well as the relationship between structure and selectivity of the macrocycles is elaborated. The article does not, however, attempt to cover all of the different approaches to these toxic metal ions extraction.

  18. Crystal and electronic structure of PbTe/CdTe nanostructures

    Directory of Open Access Journals (Sweden)

    Sankowski Piotr

    2011-01-01

    Full Text Available Abstract In this article, the authors reported a theoretical study of structural and electronic properties of PbTe inclusions in CdTe matrix as well as CdTe nano-clusters in PbTe matrix. The structural properties are studied by ab initio methods. A tight-binding model is constructed to calculate the electron density of states (DOS of the systems. In contrast to the ab initio methods, the latter allows studying nanostructures with diameters comparable to the real ones. The calculations show that both kinds of inclusions lead to changes of the DOS of the carriers near the Fermi level, which may affect optical, electrical and thermoelectric properties of the material. These changes depend on the size, shape, and concentration of inclusions.

  19. Effect of ZnSe and CdSe nanoparticles on the fluorescence and optical band gap of Sm3+ doped lead borate glasses

    Science.gov (United States)

    Fatokun, Stephen O.

    For the first part of this work, we prepared a series of Sm-doped lead borate (PbO-B2O3) glasses containing zinc selenide (ZnSe) and cadmium selenide (CdSe) nanoparticles (NPs) and studied the Sm 3+ fluorescence by varying the glass composition and size of the NPs. We have chosen these heavy metal oxide glasses to incorporate Sm3+ ions because they have large glass forming region, high refractive index, and good physical and thermal stability. Lead borate glasses with the following compositions xPbO:(96.5-x)B2O 3:0.5Sm2O3:3ZnSe/CdSe, x=36.5 and 56.5 mol%) are prepared using the melt-quenching method. Transmission electron microscopy characterization was done to confirm both nucleation and growth of the NPs for different annealing times. Fluorescence spectra of these samples are obtained with the excitation wavelengths at 403 and 477nm. Three fluorescence transitions are observed at 563 nm, 598 nm and 646 nm. The transition at 646 nm is a electric dipole (ED) transition that strongly depends on the covalency of the Sm-O bond and the asymmetry of the crystal field at the Sm3+ site. The 646 nm/598 nm fluorescence intensity ratio has been studied for different annealing times and PbO concentration for both ZnSe and CdSe samples. Longer annealing times tend to make the crystal field at the Sm3+ site more symmetric in nature for these glasses. The presence of CdSe NPs is seen to produce the greatest influence on the fluorescence intensity ratio. This is believed to be due to the larger size of the CdSe nanoparticles and its stronger influence on Sm3+ ions. The second part of this work was dedicated to the understanding of the optical band gap of samarium doped lead borate glasses with and without ZnSe/CdSe NPs. Optical absorption spectra for all these glass samples show their absorption edge in the ultraviolet region. Detailed analysis of the absorption edge was carried out using the Mott-Davis model and the optical band gap and the width of the tail in the band gap

  20. Cancer Cell Targeting Using Folic Acid/Anti-HER2 Antibody Conjugated Fluorescent CdSe/CdS/ZnS-Mercaptopropionic Acid and CdTe-Mercaptosuccinic Acid Quantum Dots.

    Science.gov (United States)

    Singh, Gurpal; Kumar, Manoj; Soni, Udit; Arora, Vikas; Bansal, Vivek; Gupta, Dikshi; Bhat, Madhusudan; Dinda, Amit K; Sapra, Sameer; Singh, Harpal

    2016-01-01

    CdSe/CdS/ZnS and CdTe quantum dots (QDs) were synthesized by successive ion layer adsorption and reaction (SILAR) technique and direct aqueous synthesis respectively using thiol stabilizers. Synthesized CdSe/CdS/ZnS and CdTe QDs stabilized with 3-mercaptopropionic acid (MPA) and mercaptosuccinic acid (MSA) were used as fluorescent labels after conjugation with folic acid (FA) and anti-HER2 antibodies. Photoluminescence quantum yield of folated CdSe/CdS/ZnS-MPA and CdTe-MSA QDs was 59% and 77% than that of non-folated hydrophilic QDs. The folate receptor-mediated delivery of folic acid-conjugated CdTe-MSA and CdSe/CdS/ZnS-MPA QDs showed higher cellular internalization as observed by confocal laser scanning microscopic studies. Folated and non-folated CdTe-MSA QDs were highly toxic and exhibited only 10% cell viability as compared to > 80% cell viability with CdSe/CdS/ZnS-MPA QDs over the concentration ranging from 3.38 to 50 pmoles. Immunohistochemistry (IHC) results of human breast cancer tissue samples showed positive results with anti-HER2 antibody conjugated CdSe/CdS/ZnS-MPA QDs with better sensitivity and specificity as compared to conventional IHC analysis using diaminobenzedene staining. PMID:27398438

  1. Quantum dot cosensitized solar cell based on PMOT@CdSe@ZnO core shell nanostructures with dual emission

    Science.gov (United States)

    Sehgal, Preeti; Narula, Anudeep Kumar

    2016-01-01

    Quantum dot sensitized solar cell based on poly(3-methoxythiophene) (PMOT)@CdSe@ZnO core shell nanostructure were synthesized where PMOT serves as hole transport material, CdSe acts as a photosensitizer which enhances visible range absorption and also helps in injection of electrons from PMOT to ZnO where ZnO provides channel for efficient electron transport. The properties of the device were assessed with and without CdSe quantum dots and effect of annealing was also observed on the device. After the addition of CdSe QDs, the visible light absorption of PMOT@ZnO was enhanced due to increase in surface area. PMOT@CdSe@ZnO exhibited dual emission, where CdSe and ZnO exhibited visible and UV emission respectively. The interface formed between PMOT and CdSe improves the charge separation. The better photovoltaic measurement of PMOT@CdSe@ZnO over CdSe@ZnO indicates that PMOT efficiently dissociate excitons at interface and suppress the interfacial charge recombination. A power conversion efficiency of 0.989% was attained for the device PMOT@CdSe@ZnO with Voc=0.56 V and Jsc=2.5 mA/cm2. Upon annealing, the efficiency of the device was enhanced to 1.1609% with Voc=0.58, Jsc=3.2 mA/cm2.

  2. Determination of Cd, Cr and Pb in phosphate fertilizers by laser-induced breakdown spectroscopy

    Science.gov (United States)

    Nunes, Lidiane Cristina; de Carvalho, Gabriel Gustinelli Arantes; Santos, Dario; Krug, Francisco José

    2014-07-01

    A validated method for quantitative determination of Cd, Cr, and Pb in phosphate fertilizers by laser-induced breakdown spectroscopy (LIBS) is presented. Laboratory samples were comminuted and homogenized by cryogenic or planetary ball milling, pressed into pellets and analyzed by LIBS. The experimental setup was designed by using a Q-switched Nd:YAG at 1064 nm with 10 Hz repetition rate, and the intensity signals from Cd II 214.441 nm, Cr II 267.716 nm and Pb II 220.353 nm emission lines were measured by using a spectrometer furnished with an intensified charge-coupled device. LIBS parameters (laser fluence, lens-to-sample distance, delay time, integration time gate, number of sites and number of laser pulses per site) were chosen after univariate experiments with a pellet of NIST SRM 695 (Trace Elements in Multi-Nutrient Fertilizer). Calibration and validation were carried out with 30 fertilizer samples from single superphosphate, triple superphosphate, monoammonium phosphate, and NPK mixtures. Good results were obtained by using 30 pulses of 50 J cm- 2 (750 μm spot size), 2.0 μs delay time and 5.0 μs integration time gate. No significant differences between Cd, Cr, and Pb mass fractions determined by the proposed LIBS method and by ICP OES after microwave-assisted acid digestion (AOAC 2006.03 Official Method) were found at 95% confidence level. The limits of detection of 1 mg kg- 1 Cd, 2 mg kg- 1 Cr and 15 mg kg- 1 Pb and the precision (coefficients of variation of results ranging from 2% to 15%) indicate that the proposed LIBS method can be recommended for the determination of these analytes in phosphate fertilizers.

  3. Biosorption mechanisms of Cd2+, Cu'2+, and Pb2+ using micro granules of sargassum cristaefolium

    International Nuclear Information System (INIS)

    The physico-chemical removal of toxic heavy metals from wastewater systems by inexpensive alternatives is a desired environmental clean-up strategy. Biosorption is one alternative that requires biomass with high metal uptake, selectivity and an ability to cope with mechanical stress in bioremediation conditions. The biosorption mechanisms of Cd2+, Cu2+ and Pb2+ by micro granules of brown algae (Sargassum cristaefolium) were investigated on a series of batch experiments coupled with Flame Atomic Absorption (FAAS) spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, Energy Dispersive X-ray (EDX), and Scanning Electron Microscopy analyses. It was observed that soluble ions of Cd2+, Cu2+ and Pb2+ could be removed by micro granules of brown algae through possible mechanisms of ion exchange, chelation, chemical precipitation, and binding to extracellular polymer. Lead exhibits the highest affinity to the algal biomass followed by copper and cadmium, SEM analysis showed uptake of Cd2+, Cu2+ and PB2+ by Sargassum cristaefolium could bring about significant morphological changes such as distortion and disorientation of the surface layers. This phenomenon signifies depositions of metals in the cell wall matrix of the brown algae. Significant changes in the FTIR and EDX spectrum were observed after Cd2+, Cu2+ and Pb2+ sorption, which stipulated the participation of surface functional groups associated with hydroxyl groups of alcohol in sorption interactions; and during the ion exchange process, ions (Ca2+,Mg2+, H+,Na+, and K+) originally present in the algal biomass were displaced by the heavy metals under study. (author)

  4. [Immobilization remediation of Cd and Pb contaminated soil: remediation potential and soil environmental quality].

    Science.gov (United States)

    Sun, Yue-Bing; Wang, Peng-Chao; Xu, Ying-Ming; Sun, Yang; Qin, Xu; Zhao, Li-Jie; Wang, Lin; Liang, Xue-Feng

    2014-12-01

    A pot experiment was conducted to investigate the immobilization remediation effects of sepiolite on soils artificially combined contamination by Cd and Pb using a set of various pH and speciation of Cd and Pb in soil, heavy metal concentration in Oryza sativa L., and soil enzyme activity and microbial quantity. Results showed that the addition of sepiolite increased the soil pH, and the exchangeable fraction of heavy metals was converted into Fe-Mn oxide, organic and residual forms, the concentration of exchangeable form of Cd and Pb reduced by 1.4% - 72.9% and 11.8% - 51.4%, respectively, when compared with the control. The contents of heavy metals decreased with increasing sepiolite, with the maximal Cd reduction of 39.8%, 36.4%, 55.2% and 32.4%, respectively, and 22.1%, 54.6%, 43.5% and 17.8% for Pb, respectively, in the stems, leaves, brown rice and husk in contrast to CK. The addition of sepiolite could improve the soil environmental quality, the catalase and urease activities and the amount of bacteria and actinomycete were increased to some extents. Although the fungi number and invertase activity were inhibited compared with the control group, it was not significantly different (P > 0.05). The significant correlation between pH, available heavy metal content, urease and invertase activities and heavy metal concentration in the plants indicated that these parameters could be used to evaluate the effectiveness of stabilization remediation of heavy metal contaminated soil. PMID:25826946

  5. Blue electroluminescence from Sb-ZnO/Cd-ZnO/Ga-ZnO heterojunction diode fabricated by dual ion beam sputtering.

    Science.gov (United States)

    Pandey, Sushil Kumar; Awasthi, Vishnu; Verma, Shruti; Mukherjee, Shaibal

    2014-12-15

    p-type Sb-doped ZnO/i-CdZnO/n-type Ga-doped ZnO was grown by dual ion beam sputtering deposition system. Current-voltage characteristics of the heterojunction showed a diode-like rectifying behavior with a turn-on voltage of ~5 V. The diode yielded blue electroluminescence emissions at around 446 nm in forward biased condition at room temperature. The emission intensity increased with the increase of the injection current. A red shifting of the emission peak position was observed with the increment of ambient temperature, indicating a change of band gap of the CdZnO active layer with temperature in low-temperature measurement. PMID:25607047

  6. Field evaluation of the effectiveness of three industrial by-products as organic amendments for phytostabilization of a Pb/Zn mine tailings.

    Science.gov (United States)

    Yang, Shengxiang; Cao, Jianbing; Li, Fengmei; Peng, Xizhu; Peng, Qingjing; Yang, Zhihui; Chai, Liyuan

    2016-01-01

    Although the potential of industrial by-products as organic amendments for phytostabilization has long been recognized, most of the previous studies addressing this issue have been laboratory-based. In this study, a field trial was conducted to evaluate the effectiveness of three industrial by-products [sweet sorghum vinasse (SSV), medicinal herb residues (MHR) and spent mushroom compost (SMC)] as organic amendments for phytostabilization of abandoned Pb/Zn mine tailings. Our results showed the following: (i) when compared to the control tailings, the mean concentrations of diethylene-triamine-pentaacetic acid (DTPA)-extractable Cd, Cu, Pb and Zn in SSV, MHR and SMC treatments decreased by 20.8-28.0%, 41.6-49.1%, 17.7-22.7% and 9.5-14.7%, respectively; (ii) the mean values of organic C, ammonium-N and available P in SSV, MHR and SMC treatments increased by 1.7-2.8, 10.8-14.9 and 3.9-5.1 times as compared with the mine tailings; and (iii) the addition of SSV, MHR and SMC significantly enhanced soil respiration and microbial biomass being 1.5-1.8 and 1.3-1.6 fold higher than those in the control tailings. There were no significant differences in soil biochemical properties among the plots amended with these by-products, suggesting that they were almost equally effective in improving the biochemical conditions of the tailings. In addition, the application of these amendments promoted seed germination, seedling growth, and consequently increased the vegetation cover and its biomass. Moreover, concentrations of Cd, Cu, Pb and Zn in above-ground parts of the plants were below the toxicity limit levels for animals. The results obtained in this field study confirmed that the three organic-rich industrial by-products could be used as amendments for phytostabilization of some types of mine tailings. PMID:26611119

  7. Percentage of toxic trace elements; Pb, Cr and Cd in certain plastic toys, Isfahan City

    Directory of Open Access Journals (Sweden)

    F Kavehzadeh

    2006-04-01

    Full Text Available Introduction: Recent investigations have detected the presence of significant levels of heavy metals (chromium, lead and cadmium in toys and other PVC products manufactured for children. In some countries, addition of compounds containing toxic metals to toys are limited or prohibited. Methods: To evaluate the safety of some of the plastic toys in the city of Isfahan with respect to toxic trace metals, pb, cr and cd, 75 samples of three types of toys were collected from the toy shop’s and were digested with acid with the two methods ISIRI and ASTM. The heavy metals were determined using atomic absorption spectrophotometer. Variance analysis and T-test were used for data analysis. Results: The result of the study showed that the products tested contained lead, chromium and cadmium and the highest and lowest concentration were related to Pb and Cd, respectively. The statistical analysis of the samples showed that there are no significant differences between ASTM and ISIRI digestion methods. The study revealed that none of the heavy metals in the toy samples exceeded the recommended standard levels. Highest average concentration of Pb and Cd were related to toys with green color and the highest Cr concentration was related to yellow toys in this study. Conclusion: Extensive studies are required to evaluate the quality of the toys being used by children and the toxic trace elements should be eliminated from the plastic materials used for making toys.

  8. Optical properties of type-I PbSe/CdSe core/shell quantum dot

    International Nuclear Information System (INIS)

    Electronic properties and optical properties of exciton in a PbSe/CdSe core/shell quantum dot are investigated taking into account the spatial confinement effect. The present model is based on the PbSe/CdSe quantum dot for type-I confinement regime. The dielectric mismatch effect and the self polarization potential are taken into consideration in the PbSe/CdSe quantum dot nanostructure. Polarization charges are incorporated at the interface of the core/shell materials. Numerical calculations on the electronic and optical properties are found with the ratio of radius of inner and outer shell materials for various shell radii. The exciton binding energy and the interband optical transition energies are computed using variational formulism within the single band effective mass approximation. The oscillator strength and the recombination life time are determined with the ratio of radius of core to shell materials taking into account the dielectric mismatch between the materials. The nonlinear absorption coefficients and the changes of refractive index are computed for the ground and first excited state using compact density matrix method. The obtained results are found to be in good agreement with those reported by other investigators

  9. Distribution Characteristics, Concentrations, and Sources of Cd and Pb in Laoxiawan Channel Sediments from Zhuzhou, China.

    Science.gov (United States)

    Chen, Wen-Wen; Zhang, Jian-Xin; Abass, Olusegun-Kazeem; Wen, Xin-Yu; Huang, Huan-Fang; Qu, Cheng-Kai; Qi, Shi-Hua

    2016-06-01

    Twenty sediment cores encompassing surface (0-20 cm) and deeper (50-60 cm) sediment layers were retrieved from the 3000 m-long Laoxiawan Channel, which receives industrial effluents from Zhuzhou City (China). Analytical results showed that cadmium (Cd) concentrations ranged between 115.7-1126.7 and 108.8-2059.3 mg/kg while lead (Pb) values ranged between 234-3000 and 145-4292 mg/kg in the surface and bottom sediments, respectively. The results also indicated that high levels of Cd and Pb were present in the vicinity of the channel mouth and confluence area. Indices for potential ecological risk and geo-accumulation were used to evaluate the environmental effects and intensity of heavy metal pollution over time. High concentrations of Cd and Pb in the bottom sediments of Laoxiawan Channel were mainly associated with wastewater discharge (10(6) m(3)/year). Thus, the Laoxiawan Channel may be an important metal contaminant source for the Xiang River. PMID:27025765

  10. Growth of CdZnTe Crystals for Radiation Detector Applications by Directional Solidification

    Science.gov (United States)

    Su, Ching-Hua

    2014-01-01

    Advances in Cadmium Zinc Telluride (Cd(sub 1-x)Zn(sub x)Te) growth techniques are needed for the production of large-scale arrays of gamma and x-ray astronomy. The research objective is to develop crystal growth recipes and techniques to obtain large, high quality CdZnTe single crystal with reduced defects, such as charge trapping, twinning, and tellurium precipitates, which degrade the performance of CdZnTe and, at the same time, to increase the yield of usable material from the CdZnTe ingot. A low gravity material experiment, "Crystal Growth of Ternary Compound Semiconductors in Low Gravity Environment", will be performed in the Material Science Research Rack (MSRR) on International Space Station (ISS). One section of the flight experiment is the melt growth of CdZnTe ternary compounds. This talk will focus on the ground-based studies on the growth of Cd(sub 0.80)Zn(sub 0.20)Te crystals for radiation detector applications by directional solidification. In this investigation, we have improved the properties that are most critical for the detector applications (electrical properties and crystalline quality): a) Electrical resistivity: use high purity starting materials (with reproducible impurity levels) and controlled Cd over pressure during growth to reproducibly balance the impurity levels and Cd vacancy concentration b) Crystalline quality: use ultra-clean growth ampoule (no wetting after growth), optimized thermal profile and ampoule design, as well as a technique for supercool reduction to growth large single crystal with high crystalline quality

  11. Extraction and isolation of the salidroside-type metabolite from zinc (Zn) and cadmium (Cd) hyperaccumulator Sedum alfredii Hance*

    OpenAIRE

    Xing, Yan; Peng, Hong-yun; Li, Xia; Zhang, Meng-Xi; Gao, Ling-Ling; Yang, Xiao-e

    2012-01-01

    The active metabolite in the post-harvested biomass of zinc (Zn) and cadmium (Cd) hyperaccumulator Sedum alfredii Hance from phytoextraction is of great interest in China. The current study demonstrates that a salidroside-type metabolite can be yielded from the Zn/Cd hyperaccumulator S. alfredii biomass by means of sonication/ethanol extraction and macroporous resin column (AB-8 type) isolation. The concentrations of Zn and Cd in the salidroside-type metabolite were below the limitation of th...

  12. Ultrasonic semi-solid coating soldering 6061 aluminum alloys with Sn-Pb-Zn alloys.

    Science.gov (United States)

    Yu, Xin-ye; Xing, Wen-qing; Ding, Min

    2016-07-01

    In this paper, 6061 aluminum alloys were soldered without a flux by the ultrasonic semi-solid coating soldering at a low temperature. According to the analyses, it could be obtained that the following results. The effect of ultrasound on the coating which promoted processes of metallurgical reaction between the components of the solder and 6061 aluminum alloys due to the thermal effect. Al2Zn3 was obtained near the interface. When the solder was in semi-solid state, the connection was completed. Ultimately, the interlayer mainly composed of three kinds of microstructure zones: α-Pb solid solution phases, β-Sn phases and Sn-Pb eutectic phases. The strength of the joints was improved significantly with the minimum shear strength approaching 101MPa. PMID:26964943

  13. Use of Sequential, Single and Kinetic Extractive Schemes to Assess Cadmium (Cd) and Lead (Pb) Availability in Vietnamese Urban Soils

    OpenAIRE

    Nastaran Manouchehri; Thi Minh Loi Nguyen; Stéphane Besancon; Lan Anh Le; Alain Bermond

    2014-01-01

    Modified BCR sequential extraction, single equilibrium-based EDTA extraction and kinetic fractionation were used for estimating the Pb and Cd availability in a series of soil samples from 3 sites located in urban areas of Hanoi (Vietnam). These schemes were compared to identify a simple, rapid and cheap protocol for routine estimation of Pb and Cd remobilizable fraction and the related potential risk. The comparison of these three approaches revealed their convergence in terms of mobility pat...

  14. Cd, Pb and Hg Biomonitoring in Fish of the Mediterranean Region and Risk Estimations on Fish Consumption

    OpenAIRE

    Elisavet A. Renieri; Alegakis, Athanasios K; Michalis Kiriakakis; Marco Vinceti; Eren Ozcagli; Wilks, Martin F.; TSATSAKIS, ARISTIDIS M.

    2014-01-01

    Cadmium (Cd), lead (Pb) and mercury (Hg) are toxic metals with increasing interest due to their tendency to bioaccumulate in fish tissue which may pose a threat to human health via fish consumption. This review of the recent literature on Cd, Pb, Hg levels summarizes data of fish biomonitoring studies in the Mediterranean Sea in order to determine potential risks due to dietary intake of metals. The analytical methods applied are described, with Atomic Absorption Spectroscopy and Inductively ...

  15. Optimizing the synthesis of CdS/ZnS core/shell semiconductor nanocrystals for bioimaging applications

    OpenAIRE

    Li-wei Liu; Si-yi Hu; Ying Pan; Jia-qi Zhang; Yue-shu Feng; Xi-he Zhang

    2014-01-01

    In this study, we report on CdS/ZnS nanocrystals as a luminescence probe for bioimaging applications. CdS nanocrystals capped with a ZnS shell had enhanced luminescence intensity, stronger stability and exhibited a longer lifetime compared to uncapped CdS. The CdS/ZnS nanocrystals were stabilized in Pluronic F127 block copolymer micelles, offering an optically and colloidally stable contrast agents for in vitro and in vivo imaging. Photostability test exhibited that the ZnS protective shell n...

  16. Te inclusion-induced electrical field perturbation in CdZnTe single crystals revealed by Kelvin probe force microscopy.

    Science.gov (United States)

    Gu, Yaxu; Jie, Wanqi; Li, Linglong; Xu, Yadong; Yang, Yaodong; Ren, Jie; Zha, Gangqiang; Wang, Tao; Xu, Lingyan; He, Yihui; Xi, Shouzhi

    2016-09-01

    To understand the effects of tellurium (Te) inclusions on the device performance of CdZnTe radiation detectors, the perturbation of the electrical field in and around Te inclusions was studied in CdZnTe single crystals via Kelvin probe force microscopy (KPFM). Te inclusions were proved to act as lower potential centers with respect to surrounding CdZnTe matrix. Based on the KPFM results, the energy band diagram at the Te/CdZnTe interface was established, and the bias-dependent effects of Te inclusion on carrier transportation is discussed. PMID:27376976

  17. Determination of Cd, Cr and Pb in phosphate fertilizers by laser-induced breakdown spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Nunes, Lidiane Cristina; Gustinelli Arantes de Carvalho, Gabriel [NAPTISA Research Support Center “Technology and Innovation for a Sustainable Agriculture”, Center for Nuclear Energy in Agriculture, University of São Paulo, Av. Centenário 303, 13416-000, Piracicaba SP (Brazil); Santos, Dario [Federal University of São Paulo, R. Prof. Artur Riedel 275, 09972-270, Diadema SP (Brazil); Krug, Francisco José, E-mail: fjkrug@cena.usp.br [NAPTISA Research Support Center “Technology and Innovation for a Sustainable Agriculture”, Center for Nuclear Energy in Agriculture, University of São Paulo, Av. Centenário 303, 13416-000, Piracicaba SP (Brazil)

    2014-07-01

    A validated method for quantitative determination of Cd, Cr, and Pb in phosphate fertilizers by laser-induced breakdown spectroscopy (LIBS) is presented. Laboratory samples were comminuted and homogenized by cryogenic or planetary ball milling, pressed into pellets and analyzed by LIBS. The experimental setup was designed by using a Q-switched Nd:YAG at 1064 nm with 10 Hz repetition rate, and the intensity signals from Cd II 214.441 nm, Cr II 267.716 nm an