WorldWideScience

Sample records for cd pb zn

  1. Assessment of Cu, Pb, Zn, and Cd in groundwater in areas around ...

    African Journals Online (AJOL)

    Assessment of Cu, Pb, Zn, and Cd in groundwater in areas around the derelict Enyigba Mines, south eastern Nigeria. ... pollution arises partly from direct absorption of toxins through ingestion of water polluted with Cd and possibly Pb. The high Cd/Zn ratio (1 - 67) however may provide some sort of control on Cd poisoning.

  2. Adsorption of Pb, Cd, Zn, Cu and Hg ions on Formaldehyde and ...

    African Journals Online (AJOL)

    MICHAEL

    The calculated value from Freundlich adsorption parameter (KF) and Langmuir adsorption parameter (qmax) showed that the adsorption capacities of the metal ions are in order of Pb2+ > Cd2+ > Zn2+ > Hg2+. > Cu2+ for formaldehyde modified bean husks and Hg2+ > Cd2+ > Pb2+ > Zn2+ > Cu2+ for pyridine modified ...

  3. Pine bark as bio-adsorbent for Cd, Cu, Ni, Pb and Zn

    DEFF Research Database (Denmark)

    Cutillas-Barreiro, L.; Ansias-Manso, L.; Fernandez Calviño, David

    2014-01-01

    % for Pb2+, 83-84% for Cu2+, 78-84% for Cd2+, 77-83% for Zn2+, and 70-75% for Ni2+, and it was faster for low concentrations, with Pb suffering the highest retention, followed by Cu, Cd, Ni and Zn. The fitting to the Freundlich and Langmuir models was satisfactory. Desorption increased in parallel...

  4. Adsorption of Pb, Cd, Zn, Cu and Hg ions on Formaldehyde and ...

    African Journals Online (AJOL)

    Adsorption of Pb(II), Cd(II), Zn(II), Cu(II) and Hg(II) ions on formaldehyde and Pyridine modified bean husks were determined. The adsorption capacity of formaldehyde modified bean husks (mg/g) was: Pb2+, 5.01; Cd2+, 3.63; Zn2+, 2.18; Hg2+, 1.82; Cu2+, 1.58 and that of pyridine modified bean husk was: Hg2+, 6.92; Cd2+ ...

  5. Zn, Pb, Cr and Cd concentrations in fish, water and sediment from ...

    African Journals Online (AJOL)

    Gills, intestine and muscle samples of O niloticus, water and surface sediments of Azuabie Creek and a central station were collected and analysed for Zn, Pb, Cr and Cd using AAS model 210VGP Buck Scientific USA. Heavy metal concentrations in fish muscle show high concentration especially Pb which is far above the ...

  6. Metal (Pb, Cd, and Zn) Binding to Diverse Organic Matter Samples and Implications for Speciation Modeling.

    Science.gov (United States)

    Chen, Weibin; Guéguen, Céline; Smith, D Scott; Galceran, Josep; Puy, Jaume; Companys, Encarnació

    2018-04-03

    This study evaluated the influence of dissolved organic matter (DOM) properties on the speciation of Pb, Zn, and Cd. A total of six DOM samples were categorized into autochthonous and allochthonous sources based on their absorbance and fluorescence properties. The concentration of free metal ions ( C M 2+ ) measured by titration using the absence of gradients and Nernstian equilibrium stripping (AGNES) method was compared with that predicted by the Windermere humic aqueous model (WHAM). At the same binding condition (pH, dissolved organic carbon, ionic strength, and total metal concentration) the allochthonous DOM showed a higher level of Pb binding than the autochthonous DOM (84- to 504-fold C Pb 2+ variation). This dependency, however, was less pronounced for Zn (12- to 74-fold C Zn 2+ variation) and least for Cd (2- to 14-fold C Cd 2+ variation). The WHAM performance was affected by source variation through the active DOM fraction ( F). The commonly used F = 1.3 provided reliable C Pb 2+ for allochthonous DOMs and acceptable C Cd 2+ for all DOM, but it significantly under-predicted C Pb 2+ and C Zn 2+ for autochthonous DOM. Adjusting F improved C M 2+ predictions, but the optimum F values were metal-specific (e.g., 0.03-1.9 for Pb), as shown by linear correlations with specific optical indexes. The results indicate a potential to improve WHAM by incorporating rapid measurement of DOM optical properties for site-specific F.

  7. Modelling atmospheric bulk deposition of Pb, Zn and Cd near a former Pb-Zn mine in West Greenland using transplanted Flavocetraria nivalis lichens.

    Science.gov (United States)

    Søndergaard, Jens; Bach, Lis; Asmund, Gert

    2013-03-01

    Atmospheric deposition of lead (Pb), zinc (Zn) and cadmium (Cd) was investigated near the former Black Angel Pb-Zn mine in Maarmorilik, West Greenland during 2010-2011. Thalli of the lichen Flavocetraria nivalis were transplanted from an uncontaminated site into sites near the mine and collected the following year. At 20 of the total 21 sites, concentrations of Pb, Zn and Cd were significantly elevated in lichens after 1 year of transplantation compared to initial concentrations. Elevated concentrations were observed within a distance of approx. 20 km from the mining area. Concentrations decreased with increasing distance from the mine and the relation was well described using a power function with a negative exponent (r(2)=0.90; 0.83 and 0.83 for Pb; Zn and Cd). To examine the relation between metal concentrations/uptake in lichen transplants and atmospheric bulk deposition, 10 Bergerhoff dust samplers were placed near lichen transplants and samplers and lichens were collected after a 7-weeks exposure period. A significant linear correlation was observed between metal concentrations in lichen transplants and atmospheric bulk metal deposition (r(2)=0.94; 0.88 and 0.89 for Pb; Zn and Cd). Combining the results and including an area distribution within a defined metal deposition area, the "annual" deposition of Pb, Zn and Cd as dust was estimated during the 2010-2011 snow-free period (∼5 months). The results reveal that 20 years after mine closure, 770 kg Pb, 3700 kg Zn and 24 kg Cd were still being deposited as dust per year (snow-free period only) within a distance of 20 km from the mine. Copyright © 2012 Elsevier Ltd. All rights reserved.

  8. 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)

    Wang Fayuan; Lin Xiangui; Yin Rui

    2007-01-01

    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

  9. Electrodialytic removal of Cu, Zn, Pb, and Cd from harbor sediment: Influence of changing experimental conditions

    DEFF Research Database (Denmark)

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

    2005-01-01

    was in an experiment with dry sediment (L/S 8) and a 70 mA applied current that lasted 14 days. These experimental conditions were thereafter used to remediate more strongly contaminated sediments. Regardless of the initial heavy metal concentrations in the sediments, 67-87% Cu, 79-98% Cd, 90-97% Zn, and 91-96% Pb......Electrodialytic remediation (EDR) was used to remove Cu, Zn, Pb, and Cd from contaminated harbor sediment. Extraction experiments were made prior to EDR, and the metal desorption was pH dependent but not liquid-to-solid ratio (L/S) dependent. The desorption order was Cd $GRT Zn $GRT Pb $GRT Cu...... for the removal of Cu, Zn, and Pb, probably due to oxidation of the sediments during stirring. Contrary, Cd removal was lower in the wet sediment as compared to the air-dried. The heavy metal removal was influenced by higher current strengths and varying L/S ratios. The highest removal obtained...

  10. Effects of reduction parameters on the amount of Pb, Zn, Cu and Cd ...

    African Journals Online (AJOL)

    It was found that recrystallization of hematite and melting of the gangue minerals present started at about 1100oC. At about 1150oC, the amount of Pb, Zn, Cd and Cu in the pellets were significantly reduced. Compressive strength measurements also showed that the strength of pellets reduced at 900oC or less were low ...

  11. Sequential Extraction of Cu, Cd, Pb and Zn from Soil Around ...

    African Journals Online (AJOL)

    The presence of heavy metals in soil around industrial wastes dump sites restricts their use for agricultural purpose. This study attempts to extract Cu, Cd, Pb and Zn from soils around some selected industrial wastes dump sites in Kaduna. Four dump sites were identified namely Kudenda, Kakuri, Gonigora and Dirkaniya.

  12. Effect of Pb and Cd uptake on Zn and Cu levels in hard and soft tissues of rats

    Energy Technology Data Exchange (ETDEWEB)

    Wesenberg, G.B.R.; Fosse, G.; Rasmussen, P.; Justesen, N.P.B.

    1980-01-01

    Male Wistar rats received a combination of 25 ppM PbCl/sub 2/ and 5 ppM CdCl/sub 2/ in drinking water at different developmental stages. Zn and Cu levels of incisors, molars, epiphyses, diaphyses, and kidney cortex were recorded by atomic absorption spectrophotometry. Pb-Cd uptake in rats, either via the mother through placenta or mammae, or directly in growing rats resulted in an overall decrease in Zn content of epiphyses. This may cause a decreased growth rate. There was a significant negative correlation between Pb and Zn in epiphyses. In addition, an increase in the Zn level of kidney cortex was found in animals receiving Pb-Cd from weaning until sacrifice, and through all stages there was a significant positive correlation between Zn and Cu in this tissue. Pb-Cd administration during pregnancy and/or lactation resulted in an increased storage of Cu in hard as well as soft tissues of the offspring. This storage did not take place if Pb-Cd were given after termination of the lactation period. There was a positive significant correlation between Pb and Cu in incisors and molars, and between Cd and Cu in incisors, molars, epiphyses and diaphyses. It was not possible in this study to determine whether the effect on Zn and Cu tissue levels was a result of Pb or of Cd, or if the effect was caused by the supply of the two elements in combination.

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

    International Nuclear Information System (INIS)

    Momani, K.A.; Jiries, A.G.; Jaradat, Q.M.

    1999-01-01

    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/m 3 , 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

  14. Vsebnost Cu, Mn, Zn, Cd, Cr in Pb v različnih stopnjah pridelave vina

    OpenAIRE

    Slekovec, Metka; Veber, Marjan; Kristl, Janja

    2015-01-01

    In samples taken during different stages of winemaking process (from grapes, crushed grapes, pressed pomace, must deposit, deposit of lees, must before and after clarification and wine) the Cu, Mn and Zn contents were determined by flame atomic absorption spectrometry (FAAS) and the Cd, Pb and Cr contents were determined by electrothermal atomic absorption spectrometry (ETAAS). Grapes, crushed grapes, pressed pomace, must deposit and deposit of lees were microwave digested with nitric acid, h...

  15. An in vivo invertebrate bioassay of Pb, Zn and Cd stabilization in contaminated soil.

    Science.gov (United States)

    Udovic, Metka; Drobne, Damjana; Lestan, Domen

    2013-08-01

    The terrestrial isopod (Porcellio scaber) was used to assess the remediation efficiency of limestone and a mixture of gravel sludge and red mud as stabilizing agents of Pb, Zn and Cd in industrially polluted soil, which contains 800, 540 and 7mgkg(-1) of Pb, Zn and Cd, respectively. The aim of our study was to compare and evaluate the results of the biological and non-biological assessment of metal bioavailability after soil remediation. Results of a 14d bioaccumulation test with P. scaber showed that that Pb and Zn stabilization were more successful with gravel sludge and red mud, while Cd was better stabilized and thus less bioavailable following limestone treatment. In vivo bioaccumulation tests confirmed the results of chemical bioaccessibility, however it was more sensitive. Biotesting with isopods is a relevant approach for fast screening of bioavailability of metals in soils which includes temporal and spatial components. Bioavailability assessed by P. scaber is a more relevant and sensitive measure of metal bioavailability than chemical bioaccessibility testing in remediated industrially polluted soil. Copyright © 2013 Elsevier Ltd. All rights reserved.

  16. Determination of Zn, Pb, Cd and Cu contents in raw milk from Khorram-Abad dairies

    Directory of Open Access Journals (Sweden)

    S. Sobhanardakani

    2016-08-01

    Full Text Available Heavy metals are the most important chemical pollutants of foods. Milk and dairy products due to the nutritional functions are largely consumed by infants and children around the world. The purpose of this study was to analyze Zn, Pb, Cd and Cu contents in raw cow milks produced in dairies of Lorestan industrial livestock zone during 2014. A total of 24 milk samples was collected from eight dairies. The samples were subjected to acid digestion according to standard method. Afterwards, the metal contents were determined using ICP-OES. All statistical analyses were performed using the SPSS statistical package. The results showed that mean concentrations of Zn, Pb, Cd and Cu in milk samples were 3072±674, 2720±2790, 104±18.5 and 142±149 µg/kg, respectively. Also comparison of the mean concentrations of the metals with the WHO maximum permissible limits in milk revealed that the mean concentrations of all metals were significantly higher than permissible limits. Because of the mean concentrations of Zn, Pb, Cd and Cu in milk samples were higher than Mean Residual Limits, therefore to achieve the consumers’ safety, monitoring of feed intake, water supplies, soil properties around livestock and forage crops and control of pollutants emission from industries near the livestock are recommended.

  17. Conventional crops and organic amendments for Pb, Cd and Zn treatment at a severely contaminated site.

    Science.gov (United States)

    Pichtel, J; Bradway, D J

    2008-03-01

    The ability of selected plants and amendments to treat Pb, Cd and Zn accumulations from a metalliferous waste disposal site was studied both in the greenhouse and field. Spinach (Spinacea oleracea), cabbage (Brassica oleracea), and a grass-legume mix (red fescue, Festuca rubra; ryegrass, Lolium perenne); and bean (Vicia faba) were grown in the greenhouse on blast furnace slag or baghouse dust amended with composted peat (CP). All plant species accumulated Pb, Cd and Zn to varying degrees. Total soil metal concentrations had a marked influence on plant uptake. Topdressing versus incorporating CP had a significant (p<0.05) effect on spinach and cabbage tissue metal concentrations. Soil Pb and Zn tended to shift towards less bioavailable forms after treatment with CP. Field plots were treated with CP, farmyard manure (FYM), or inorganic fertilizer. Dry matter production of spinach, cabbage and a grass-legume mix was greatest on either the CP or FYM treatments. Phytostabilization in combination with organic amendments may be the most appropriate technology to ensure stabilization of soil metals at this site.

  18. ASSESSMENT OF Pb, Cd, Cu AND Zn AVAILABILITY FOR PLANTS IN BAIA MARE MINING REGION

    Directory of Open Access Journals (Sweden)

    LEVEI ERIKA-ANDREA

    2010-12-01

    Full Text Available In order to evaluate the mobility of heavy metals in soil from Baia Mare mining region, the total, water and DTPA extractable metal contents were determined. The results showed that despite the high total metals contents and the high percentages of plant available metals only a low percent was water soluble, indicating a potential accumulation of metals in trophic chain and a potential risk for public health. Among the investigated metals, the plant available Pb and Cd species are the most severe contaminants. Significant correlations between total and DTPA extractable metals were found for Cu (r=0.510 and Pb (0.418, and also an affinity between total and water extractable metals were identified for Cu (0.366, Pb (0.502 and Zn (0.597.

  19. Lethal critical body residues as measures of Cd, Pb, and Zn bioavailability and toxicity in the earthworm Eisenia fetida

    Energy Technology Data Exchange (ETDEWEB)

    Conder, J.M.; Lanno, R.P. [Oklahoma State Univ., Dept. of Zoology, Stillwater, OK (United States)

    2003-07-01

    Background. Earthworm heavy metal concentrations (critical body residues, CBRs) may be the most relevant measures of heavy metal bioavailability in soils and may be linkable to toxic effects in order to better assess soil ecotoxicity. However, as earthworms possess physiological mechanisms to secrete and/or sequester absorbed metals as toxicologically inactive forms, total earthworm metal concentrations may not relate well with toxicity. Objective. The objectives of this research were to: i) develop LD{sub 50}s (total earthworm metal concentration associated with 50% mortality) for Cd, Pb, and Zn; ii) evaluate the LD{sub 50} for Zn in a lethal Zn-smelter soil; iii) evaluate the lethal mixture toxicity of Cd, Pb, and Zn using earthworm metal concentrations and the toxic unit (TU) approach; and iv) evaluate total and fractionated earthworm concentrations as indicators of sublethal exposure. Methods. Earthworms (Eisenia fetida (Savigny)) were exposed to artificial soils spiked with Cd, Pb, Zn, and a Cd-Pb-Zn equitoxic mixture to estimate lethal CBRs and mixture toxicity. To evaluate the CBR developed for Zn, earthworms were also exposed to Zn-contaminated field soils receiving three different remediation treatments. Earthworm metal concentrations were measured using a procedure devised to isolate toxicologically active metal burdens via separation into cytosolic and pellet fractions. (orig.)

  20. Immobilization of Cu, Zn, Cd and Pb in mine drainage stream sediment using Chinese loess.

    Science.gov (United States)

    Zang, Fei; Wang, Shengli; Nan, Zhongren; Ma, Jianmin; Li, Yepu; Zhang, Qian; Chen, Yazhou

    2017-08-01

    The in situ immobilization of metal-contaminated sediment, using various amendments, has attracted great attention owing to their cost-effectiveness. The present study investigated the effectiveness of Chinese loess on Cu, Zn, Cd and Pb stabilization by decreasing their bioavailability in contaminated sediment. The loess was mixed with the sediment in doses of 0, 0.5, 1, 2, 5, 10 and 20 kg. Approximately 70 d after loess application, the effectiveness was evaluated using the Tessier sequential extraction procedure and single extractants, including ethylenediaminetetraacetic acid disodium salt (EDTA-2Na), diethylenetriaminepentaacetic acid (DTPA), calcium chloride (CaCl 2 ) and hydrochloric acid (HCl). The results indicated that the loess can effectively transform Cu from the carbonate fraction into the residual fraction when the loess dose was ≥5 kg. However, loess had little effect on Zn, Cd and Pb immobilization. Correlation analysis showed that these four extractants can provide a good indication of the toxicity of Cu, Zn, Cd and Pb in the amended sediment. Additionally, the organic matter content in the amended sediment decreased by 1.4% for CK, 1.6% for L0.5, 1.7% for L1, 1.5% for L2, 1.5% for L5, 1.9% for L10 and 1.9% for L20 (CK: untreated sediment; L0.5 to L20 represent loess doses of 0.5, 1, 2, 5, 10 and 20 kg, respectively) compared to the initial organic matter content in the unamended sediment, which may increase the atmospheric carbon dioxide owing to the degradation of organic matter. Copyright © 2017 Elsevier Ltd. All rights reserved.

  1. Pb(II), Cd(II) and Zn(II) adsorption on low grade manganese ore ...

    African Journals Online (AJOL)

    Low grade manganese ore (LMO) of Orissa containing 58.37% SiO2, 25.05% MnO2, 8.8% Al2O3, and 5.03% Fe2O3 as the main constituents was taken to study its adsorption behaviour for Pb(II), Cd(II) and Zn(II) from aqueous solutions. The XRD studies showed the crystalline phases to be quartz, ß-MnO2, d-MnO2 and ...

  2. Bioavailability and health risk of some potentially toxic elements (Cd, Cu, Pb and Zn) in street dust of Asansol, India.

    Science.gov (United States)

    Gope, Manash; Masto, Reginald Ebhin; George, Joshy; Hoque, Raza Rafiqul; Balachandran, Srinivasan

    2017-04-01

    Street dust samples were collected from five different types of land use patterns (busy traffic zone, urban residential area, national highways, industrial area and sensitive area) in a medium sized industrial city Asansol, India. The samples were fractionated into ≤53µm and analyzed for potential toxic elements (PTEs) viz. Zn, Cd, Pb and Cu. The mean total concentration of Zn, Cd, Pb and Cu in the urban street dust samples were 192, 0.75, 110 and 132mgkg -1 respectively. Chemical speciation was performed for PTEs to evaluate the bio-available fractions. Cu was mostly associated with organic matter phase while Zn, Pb and Cd with residual phase. Mean mobility factor (MF) for heavy metals in Asansol was Zn (54.6%)>Pb (49.1%)>Cu (25.3%)>Cd (22.7%). Geo-chemical indices such as Enrichment Factor (EF), geo-accumulation index (Igeo) and contamination Factor (CF) were in the order of Pb>Cd>Zn>Cu. Cluster analysis was done to understand the similarities among the sites. The risks of all metals was calculated with mobile fraction, which indicated actual risk due to PTEs was less (HI<1). Copyright © 2017 Elsevier Inc. All rights reserved.

  3. Metal pollution (Cd, Pb, Zn, and As) in agricultural soils and soybean, Glycine max, in southern China.

    Science.gov (United States)

    Zhao, Yunyun; Fang, Xiaolong; Mu, Yinghui; Cheng, Yanbo; Ma, Qibin; Nian, Hai; Yang, Cunyi

    2014-04-01

    Crops produced on metal-polluted agricultural soils may lead to chronic toxicity to humans via the food chain. To assess metal pollution in agricultural soils and soybean in southern China, 30 soybean grain samples and 17 soybean-field soil samples were collected from 17 sites in southern China, and metal concentrations of samples were analyzed by graphite furnace atomic absorption spectrophotometer. The integrated pollution index was used to evaluate if the samples were contaminated by Cd, Pb, Zn and As. Results showed that Cd concentration of 12 samples, Pb concentration of 2 samples, Zn concentration of 2 samples, and As concentrations of 2 samples were above the maximum permissible levels in soils. The integrated pollution index indicated that 11 of 17 soil samples were polluted by metals. Metal concentrations in soybean grain samples ranged from 0.11 to 0.91 mg kg(-1) for Cd; 0.34 to 2.83 mg kg(-1) for Pb; 42 to 88 mg kg(-1) for Zn; and 0.26 to 5.07 mg kg(-1) for As, which means all 30 soybean grain samples were polluted by Pb, Pb/Cd, Cd/Pb/As or Pb/As. Taken together, our study provides evidence that metal pollution is an important concern in agricultural soils and soybeans in southern China.

  4. 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

  5. Study of Zn, Cd, and Pb Adsorption Using Chitin Extracted from Lobsters from Oman Sea

    Directory of Open Access Journals (Sweden)

    Alireza Sardashti

    2015-10-01

    Full Text Available Lobster shells from Konarak Port were collected in October 2002, purified, and dried for the purposes of the present study. Chitin was extracted from the shellsusing the common chemical processes of demineralization, proteinzation, and decolonization, beforepurificationwith 1% CH3COOH and 1% NaCl to obatin an extract containing 12% (w/w chitin. Chitin composition was determined using FT-IR, X-Ray powder diffraction, BET, and C.H.N.S analysis. The FT-IR spectrum of the extracted chitin was corresponded well to the Merck standard one, indicating that it is a linear polymer of N-acetyl-D- glucosamine on which metal ions can be adsorbed. Kinetic study of chitin’s reaction with Zn+2 at pH=6.75 and an ionic strength of 0.02 M indicated that adsorption equilibrium was reached within six hours of mixing. Adsorption Langmuir isotherms for a solution of Zn+2, Cd+2, and Pb+2 ions at an initial concentration of 2×10‒3 M were determined for an ionic strenght of 0.02 M, different pH levels, and at ambient temparature using the discontinued in-pot method. The maximum amounts of metal ions adsorbed on chitin at pH= 6.75 were measured to be 0.119 mol/kg for Cd+2, 0.714 mol/kg for Zn+2, and 1.630 mol/Kg for Pb+2. The overdyeing graphs, Cs= f (pH, show that the adsorption capacity of chitin is influenced by such factors as pH, reaction time, metal ion concantration, and adsorbent particle size. Thus, chitin as a non-toxic natural polymer may be highly recommended for water detoxification from heavy metal ions.

  6. Heavy metal (Cu, Zn, Cd and Pb) partitioning and bioaccessibility in uncontaminated and long-term contaminated soils

    International Nuclear Information System (INIS)

    Lamb, Dane T.; Ming Hui; Megharaj, Mallavarapu; Naidu, Ravi

    2009-01-01

    We investigated the pore-water content and speciation of copper (Cu), zinc (Zn), cadmium (Cd) and lead (Pb) in a range of uncontaminated and long-term contaminated soils in order to establish their potential bioaccessibility to soil biota, plants and humans. Among the samples, soil pH (0.01 M CaCl 2 ) ranged from 4.9 to 8.2. The total metal content of the uncontaminated soils ranged from 3.8 to 93.8 mg Cu kg -1 , 10.3 to 95 mg kg -1 Zn, 0.1 to 1.8 mg Cd kg -1 and 5.2 to 183 mg kg -1 Pb, while metal content in the contaminated soils ranged from 104 to 6841 mg Cu kg -1 , 312 to 39,000 mg kg -1 Zn, 6 to 302 mg Cd kg -1 and 609 to 12,000 mg kg -1 Pb. Our analysis of pore-water found the Cu concentrations to be much higher in contaminated soils than in uncontaminated soils, with the distribution coefficients (K d ) correlating significantly with the log of dissolved organic carbon concentrations. Despite the high total metal content of the contaminated soil, Zn, Cd and Pb were not generally found at elevated levels in the pore-water with the exception of a single contaminated soil. A long period of ageing and soil weathering may have led to a substantial reduction in heavy metal concentrations in the pore-water of contaminated soils. On the other hand, Pb bioaccessibility was found to be comparatively high in Pb contaminated soils, where it tended to exceed the total Pb values by more than 80%. We conclude that, despite the extensive ageing of some contaminated soils, the bioaccessibility of Pb remains relatively high.

  7. Efficiency of several leaching reagents on removal of Cu, Pb, Cd, and Zn from highly contaminated paddy soil.

    Science.gov (United States)

    Gao, Ruili; Zhu, Pengfei; Guo, Guangguang; Hu, Hongqing; Zhu, Jun; Fu, Qingling

    2016-11-01

    The efficiency of five different single leaching reagents (tartaric acid (TA), citric acid (CA), CaCl 2 , FeCl 3 , EDTA) and two different composite leaching reagents (CA + FeCl 3 , CA + EDTA) on removing Cu, Pb, Zn, and Cd from contaminated paddy soil in Hunan Province (in China) was studied. The results indicated that the efficiencies of CA, FeCl 3 , and EDTA on extracting Cu, Pb, Cd, and Zn from soil were greater than that of TA and CaCl 2 , and their extraction efficiencies were EDTA ≥ FeCl 3 > CA. The efficiencies of CA + FeCl 3 on extracting Cu, Pb, Cd, and Zn were higher than that of single CA or FeCl 3 . The 25 mmol L -1 CA + 20 mmol L -1 FeCl 3 was a promising composite leaching reagent for paddy soil, and it could remove Cu (57.6 %), Pb (59.3 %), Cd (84.8 %), and Zn (28.0 %), respectively. With the same amount of leaching reagent, the efficiency of continuous leaching by several times was higher than that by once. In addition, the easily reducible and oxidizable fractions of heavy metals showed significant decrease during the process of leaching.

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

    NARCIS (Netherlands)

    Rodrigues, S.R.; Cruz, N.; Coelho, C.; Henriques, B.; Carvalho, L.; Duarte, A.C.; Pereira, E.; Römkens, P.F.A.M.

    2013-01-01

    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 HNO(3) (reactive), 0.01 M CaCl(2) (available), and 0.4 M glycine at pH = 1.5, SBET method (oral

  9. Assessing comparative terrestrial ecotoxicity of Cd, Co, Cu, Ni, Pb, and Zn: The influence of aging and emission source

    DEFF Research Database (Denmark)

    Owsianiak, Mikolaj; Holm, Peter E.; Fantke, Peter

    2015-01-01

    H or soil organic carbon, emission source occasionally has an effect on reactivity of Cd, Co, Cu, Ni, Pb and Zn emitted from various anthropogenic sources followed by aging in the soil from a few years to two centuries. The uncertainties in estimating the age prevent definitive conclusions about...

  10. Metal arsonate polymers of Cd, Zn, Ag and Pb supported by 4-aminophenylarsonic acid

    Energy Technology Data Exchange (ETDEWEB)

    Lesikar-Parrish, Leslie A.; Neilson, Robert H. [Department of Chemistry, Texas Christian University, Box 298860, Fort Worth, TX 76129 (United States); Richards, Anne F., E-mail: a.richards@latrobe.edu.au [Department of Chemistry, La Trobe Institute for Molecular Sciences, La Trobe University, Melbourne, Victoria 3086 (Australia)

    2013-02-15

    The coordination preferences of 4-aminophenylarsonic acid, 4-NH{sub 2}C{sub 6}H{sub 4}AsO{sub 3}H{sub 2}, (p-arsanilic acid) with CdCl{sub 2}{center_dot}2.5H{sub 2}O, ZnCl{sub 2}, Ag(SO{sub 3}CF{sub 3}) and Pb(NO{sub 3}){sub 2} have been investigated affording five new metal arsonate polymers. The reaction between 4-aminophenylarsonic acid and CdCl{sub 2}{center_dot}2.5H{sub 2}O resulted in a one-dimensional polymer, [{l_brace}Cd(4-NH{sub 3}C{sub 6}H{sub 4}AsO{sub 3}H)(Cl){sub 2}{r_brace}(H{sub 2}O){sub 2}]{sub n}, 1, in which the polymeric chain is propagated by bridging chlorides. Exchange of CdCl{sub 2} for ZnCl{sub 2} afforded [{l_brace}Zn{sub 2}(4-NH{sub 3}C{sub 6}H{sub 4}AsO{sub 3})(Cl){sub 2}{r_brace}(H{sub 2}O){sub 2}(Cl)]{sub n}, 2, featuring interlinked 6- and 8-membered [Zn-O-As] ring systems. The reaction of Ag(SO{sub 3}CF{sub 3}) with 4-aminophenylarsonic acid, afforded polymeric 3, [Ag(4-NH{sub 2}C{sub 6}H{sub 4}AsO{sub 3}H)(4-NH{sub 2}C{sub 6}H{sub 4}AsO{sub 3}H{sub 2})]{sub n} where coordination of the amino group to the silver center is observed and [{l_brace}Ag{sub 2}(4-NH{sub 3}C{sub 6}H{sub 4}AsO{sub 3}H)(4-NH{sub 3}C{sub 6}H{sub 4}AsO{sub 3})({mu}2-SO{sub 3}CF{sub 3}){sub 2}{r_brace}(SO{sub 3}CF{sub 3}){sub 2}]{sub n}, 4. By comparison, the reaction of p-arsanilic acid with Pb(NO{sub 3}){sub 2} yielded a polymeric chain [Pb(4-NH{sub 3}C{sub 6}H{sub 4}AsO{sub 3}H)(NO{sub 3}){sub 2}]{sub n}, 5 of similar topology to 1. The structures of 1-5 have been indiscriminately characterized by single crystal X-ray diffraction and their composition supported by relevant spectroscopic techniques. A comparison of the structural features of these polymers is used to determine the coordination preference of the ligand and factors influencing structural motifs, for example, the role of the anion. - Graphical abstract: The reaction of 4-aminophenylarsonic acid, 4-NH{sub 2}C{sub 6}H{sub 4}AsO{sub 3}H{sub 2}, with cadmium, zinc, silver, and lead have resulted in

  11. Quality and content of Cu, Zn, Cd and Pb in complete fodder mixture in region of Kraljevo

    Directory of Open Access Journals (Sweden)

    Vukašinović Marija

    2002-01-01

    Full Text Available We followed the quality and content of Cu, Zn, Cd and Pb in maize fodder and complete fodder mixture (CFM for fattened bullocks in the region of Kraljevo. Quality analyses included 10 samples of CFM for bullocks under 250 kg, and 11 samples of CFM for bullocks over 250 kg, while 28 samples were analysed for content of Cu, Zn, Cd and Pb. Samples were prepared from ash for microelement content analysis and microelements were determined by the atomic absorption spectrophotometry (AAS method. The quality of CFM was determined by standard methods. We also determined dry matter content, so we expressed the content of Cu, Zn, Cd and Pb in dry matter and air-dried hay. The average content of water in CFM for bullocks under 250 kg was 10.67% ashes 4.58%, crude fibre 5.10%, proteins 14.55 %, Ca 0.83% and P 0.50 %. The average content of water in CFM for bullocks over 250 kg was 10.78%, ashes 4.44 %, crude fibre 5.26 %, proteins 13.40 %, Ca 0.85 % and P 0.51 %. The average content of Cu in maize fodder on farm A was 7.86 mg/kg, Zn 24.01 mg/kg, while Cd and Pb were not detected. Content of Cu in CFM on farm B was 7.53 mg/kg, farm C 21.30 mg/kg and farm D 75.51 mg/kg, and of Zn 40.34 mg/kg, 88.87 mg/kg and 115.61 mg/kg, respectively. The content of Cd and Pb in CFM was under maximum permitted concentrations on all farms.

  12. Testing WHAM-FTOX with laboratory toxicity data for mixtures of metals (Cu, Zn, Cd, Ag, Pb).

    Science.gov (United States)

    Tipping, Edward; Lofts, Stephen

    2015-04-01

    The Windermere humic aqueous model using the toxicity function (WHAM-FTOX ) describes cation toxicity to aquatic organisms in terms of 1) accumulation by the organism of metabolically active protons and metals at reversible binding sites, and 2) differing toxic potencies of the bound cations. Cation accumulation (νi , in mol g(-1) ) is estimated through calculations with the WHAM chemical speciation model by assuming that organism binding sites can be represented by those of humic acid. Toxicity coefficients (αi ) are combined with νi to obtain the variable FTOX (= Σ αi νi ) which, between lower and upper thresholds (FTOX,LT , FTOX,UT ), is linearly related to toxic effect. Values of αi , FTOX,LT , and FTOX,LT are obtained by fitting toxicity data. Reasonable fits (72% of variance in toxic effect explained overall) were obtained for 4 large metal mixture acute toxicity experiments involving daphnids (Cu, Zn, Cd), lettuce (Cu, Zn, Ag), and trout (Zn, Cd, Pb). Strong nonadditive effects, most apparent in results for tests involving Cd, could be explained approximately by purely chemical competition for metal accumulation. Tentative interpretation of parameter values obtained from these and other experimental data suggests the following order of bound cation toxicity: H < Al < (Cu Zn Pb UO2 ) < (Cd Ag). Another trend is a strong increase in Cd toxicity relative to that of Zn as organism complexity increases (from bacteria to fish). © 2014 SETAC.

  13. Effect of Applying Chemical Fertilizers on Concentration of Cd, Pb and Zn in Agricultural Soils

    Directory of Open Access Journals (Sweden)

    Hossein Pourmoghadas

    2017-03-01

    Full Text Available Background &Objective:  Nowadays uncontrolled uses of chemical fertilizers which have many heavy metals such as Cadmium, Lead and Zinc in addition have economic problems, cause to serious damages in the environment. Therefore uncontrolled application of fertilizers can cause accumulation contaminants in soil, water sources and increasing in plants and human & animals’ food chain. The main objective of this research was to investigate the effects of chemical fertilizers application to increase heavy metals in agricultural soils at directions to prevent contamination in water sources, agricultural products and the best uses of chemical fertilizers. Methods: In this study, 20 soil samples and 5 useful chemical fertilizer samples were collected and investigated. After fertilizer and soil samples were prepared, digested and filtered, heavy metals were determined with using atomic absorption. Results: The results of this study showed that, Cd in Diammonum phosphate  fertilizer 1.25 times, Super phosphate triple 1.7 times and in Macro granular fertilizer 1.5 times were as much as maximum acceptable concentration in chemical fertilizers. Cadmium concentration in all of the Jarghoye (Isfahan agricultural soil samples 3 to 7 times and in the Mobarake village (Najaf abad agricultural soil samples 10 to 35 times were as much as maximum acceptable concentration in agricultural soils. But Pb and Zn concentration in all of the agricultural soil samples was less than the amount of maximum acceptable concentration. Conclusion: Phosphate chemical fertilizers were positive effects to increase concentration of Pb and Zn in agricultural soils. Therefore, application of the fertilizer must be more attention because of increasing heavy metals in the agriculture soils and probably increasing heavy metals in food chain.  

  14. Effect of Cu(II), Cd(II) and Zn(II) on Pb(II) biosorption by algae Gelidium-derived materials.

    Science.gov (United States)

    Vilar, Vítor J P; Botelho, Cidália M S; Boaventura, Rui A R

    2008-06-15

    Biosorption of Pb(II), Cu(II), Cd(II) and Zn(II) from binary metal solutions onto the algae Gelidium sesquipedale, an algal industrial waste and a waste-based composite material was investigated at pH 5.3, in a batch system. Binary Pb(II)/Cu(II), Pb(II)/Cd(II) and Pb(II)/Zn(II) solutions have been tested. For the same equilibrium concentrations of both metal ions (1 mmol l(-1)), approximately 66, 85 and 86% of the total uptake capacity of the biosorbents is taken by lead ions in the systems Pb(II)/Cu(II), Pb(II)/Cd(II) and Pb(II)/Zn(II), respectively. Two-metal results were fitted to a discrete and a continuous model, showing the inhibition of the primary metal biosorption by the co-cation. The model parameters suggest that Cd(II) and Zn(II) have the same decreasing effect on the Pb(II) uptake capacity. The uptake of Pb(II) was highly sensitive to the presence of Cu(II). From the discrete model it was possible to obtain the Langmuir affinity constant for Pb(II) biosorption. The presence of the co-cations decreases the apparent affinity of Pb(II). The experimental results were successfully fitted by the continuous model, at different pH values, for each biosorbent. The following sequence for the equilibrium affinity constants was found: Pb>Cu>Cd approximately Zn.

  15. Test of experimental set-ups for electrodialytic removal of Cu, Zn, Pb and Cd from different contaminated harbour sediments

    DEFF Research Database (Denmark)

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

    2005-01-01

    Electrodialytic removal of heavy metals from different harbour sediments was investigated. Electrodialytic remediation experiments in laboratory scale were made with calcareous and non-calcareous harbour sediments. Two different experimental set-ups were used for the study, one with stirring...... of the sediment slurry, the other without stirring. The removal of heavy metals was highest in the non-calcareous sediment, where 94% Cd, 91% Zn and 73% Cu were removed after 24 days. The highest removal obtained for the calcareous sediment was 81% Cd, 76% Zn, 75% Pb and 53% Cu after 21 days, with stirred...... sediment slurry. Electrodialytic experiments without stirring of calcareous sediment gave high removals (84% Zn, 58% Pb and 48% Cu), but there were problems with precipitations in the sediment, which limited the removal. The stirred experiments gave the highest removals of heavy metals and the voltage...

  16. Population health risk via dietary exposure to trace elements (Cu, Zn, Pb, Cd, Hg, and As) in Qiqihar, Northeastern China.

    Science.gov (United States)

    Luo, Jinming; Meng, Jia; Ye, Yajie; Wang, Yongjie; Bai, Lin

    2018-02-01

    The estimated daily intakes (EDIs) of six trace elements (Cu, Zn, Pb, Cd, Hg, and As) in vegetables (leafy vegetable, i.e., bok choy, fruit vegetables, i.e., cucumber and tomato, and other categories, i.e., mushroom, kidney bean, and potato), cereals (rice and wheat flour), and meats (pork, mutton, and beef) most commonly consumed by adult inhabitants of Qiqihar, Northeastern China, were determined to assess the health status of local people. The average EDIs of Cu, Zn, Pb, Cd, Hg, and As were with 20.77 μg (kg bw) -1 day -1 of Cu, 288 μg (kg bw) -1 day -1 of Zn, 2.01 μg (kg bw) -1 day -1 of Pb, 0.41 μg (kg bw) -1 day -1 of Cd, 0.01 μg (kg bw) -1 day -1 of Hg, and 0.52 μg (kg bw) -1 day -1 of As, respectively, which are below the daily allowance recommended by FAO/WHO. However, the maximum EDIs of Pb and Cd were 4.56 μg (kg bw) -1 day -1 and 1.68 μg (kg bw) -1 day -1 , respectively, which are above the recommended levels [i.e., 3.58 μg (kg bw) -1 day -1 for Pb and 1.0 μg (kg bw) -1 day -1 for Cd] by FAO/WHO. This finding indicates that the potential health risk induced by daily ingestion of Pb and Cd for the local residents should receive a significant concern. Similarly, we detected elevated Pb and Cd concentrations, i.e., with average of 13.58 and 0.60 mg kg -1 dw, respectively, in the adult scalp hairs. Consumption of rice, potato, bok choy, and wheat flour contributed to 75 and 82% of Pb and Cd daily intake from foodstuffs. Nevertheless, human scalp hair is inappropriate biological material for determination of the nutritional status of trace elements in this region.

  17. Removal efficiency of Pb, Cd, Cu and Zn from polluted water using dithiocarbamate ligands

    Directory of Open Access Journals (Sweden)

    Rajab Abu-El-Halawa

    2017-01-01

    Full Text Available Presently, there is increased attention and focus on heavy metals, which are becoming one of the most serious environmental problems due to their adverse health effects. These toxic heavy metals are not easily degraded and require removal from polluted water to protect people and the environment. The purpose of this work was to prepare two types of dithiocarbamate ligands, one aliphatic (diethyldithiocarbamate and the other aromatic (diphenyldithiocarbamate, and to use them as chelators to remove Pb, Cd, Cu and Zn from polluted water. Dithiocarbamates were selected because they have good binding ability and can precipitate metal ions as complexes. The metal removal efficiency is compared between both ligands and also compared to the efficiency of activated carbon in an adsorption process to remove the same metals. The investigation results indicated that the diphenyldithiocarbamate ligand was more efficient in removing the studied metals than the diethyldithiocarbamate analogues. Additionally, the metal removal efficiency of the diphenyldithiocarbamate ligand was more effective than using the activated carbon method.

  18. 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.

  19. Cd, Pb, and Zn mobility and (bio)availability in contaminated soils from a former smelting site amended with biochar.

    Science.gov (United States)

    Lomaglio, Tonia; Hattab-Hambli, Nour; Miard, Florie; Lebrun, Manhattan; Nandillon, Romain; Trupiano, Dalila; Scippa, Gabriella Stefania; Gauthier, Arnaud; Motelica-Heino, Mikael; Bourgerie, Sylvain; Morabito, Domenico

    2017-07-20

    Biochar is a potential candidate for the remediation of metal(loid)-contaminated soils. However, the mechanisms of contaminant-biochar retention and release depend on the amount of soil contaminants and physicochemical characteristics, as well as the durability of the biochar contaminant complex, which may be related to the pyrolysis process parameters. The objective of the present study was to evaluate, in a former contaminated smelting site, the impact of two doses of wood biochar (2 and 5% w/w) on metal immobilization and/or phytoavailability and their effectiveness in promoting plant growth in mesocosm experiments. Different soil mixtures were investigated. The main physicochemical parameters and the Cd, Pb, and Zn contents were determined in soil and in soil pore water. Additionally, the growth, dry weight, and metal concentrations were analyzed in the different dwarf bean plant (Phaseolus vulgaris L.) organs tested. Results showed that the addition of biochar at two doses (2 and 5%) improved soil conditions by increasing soil pH, electrical conductivity, and water holding capacity. Furthermore, the application of biochar (5%) to metal-contaminated soil reduced Cd, Pb, and Zn mobility and availability, and hence their accumulation in the different P. vulgaris L. organs. In conclusion, the data clearly demonstrated that biochar application can be effectively used for Cd, Pb, and Zn immobilization, thereby reducing their bioavailability and phytotoxicity.

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

    International Nuclear Information System (INIS)

    Nguyen Giang; Nguyen Thanh Tam; Le Thi Ngoc Trinh; Truong Phuong Mai; Nguyen Van Minh

    2004-01-01

    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)

  1. The effect of storage of canned vegetables on concentration of the metals Fe, Cu, Zn, Pb, Sn, Al, Cd and Ni.

    Science.gov (United States)

    Arvanitoyannis, I

    1990-01-01

    The increase in the concentration of Fe, Cu, Zn, Pb, Sn, Al, Cd and Ni over a 2 year's time of strongly corrosive acidic vegetables (pickles) and weakly corrosive vegetables (peas, green beans, haricot beans, mushrooms) has been determined. The results show a considerable increase in Fe, Cu, Pb and Sn content with time, particularly for pickles, while the change in Al, Cd, Zn and Ni content was rather negligible.

  2. Analytisch-chemische aspecten van de bepaling van As, Ca, Cd, Sb, Sn, Pb, Zn in MVS-filterdestruaten met ICP-MS

    NARCIS (Netherlands)

    Velde-Koerts T van der; Lesquillier AI; Ritsema R; LAC

    1995-01-01

    In dit onderzoek werd een ICP-MS-methode ontwikkeld voor de bepaling van Ca, Zn, As, Cd, Sb, Sn en Pb in filterdestruaten. De onderste analysegrens is 30 ng/l Sb, 60 ng/l Cd, 200 ng/l As, 300 ng/l Sn, 400 ng/l Pb, 4 mug/l Zn en 20 mug/l Ca ; de precisie is beter dan 7% RSD voor Ca, 4% RSD voor

  3. 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.

  4. Dissolved trace metals (Ni, Zn, Co, Cd, Pb, Al, and Mn) around the Crozet Islands, Southern Ocean

    Science.gov (United States)

    Castrillejo, Maxi; Statham, Peter J.; Fones, Gary R.; Planquette, Hélène; Idrus, Farah; Roberts, Keiron

    2013-10-01

    A phytoplankton bloom shown to be naturally iron (Fe) induced occurs north of the Crozet Islands (Southern Ocean) every year, providing an ideal opportunity to study dissolved trace metal distributions within an island system located in a high nutrient low chlorophyll (HNLC) region. We present water column profiles of dissolved nickel (Ni), zinc (Zn), cobalt (Co), cadmium (Cd), lead (Pb), aluminium (Al), and manganese (Mn) obtained as part of the NERC CROZEX program during austral summer (2004-2005). Two stations (M3 and M1) were sampled downstream (north) of Crozet in the bloom area and near the islands, along with a control station (M2) in the HNLC zone upstream (south) of the islands. The general range found was for Ni, 4.64-6.31 nM; Zn, 1.59-7.75 nM; Co, 24-49 pM; Cd, 135-673 pM; Pb, 6-22 pM; Al, 0.13-2.15 nM; and Mn, 0.07-0.64 nM. Vertical profiles indicate little island influence to the south with values in the range of other trace metal deprived regions of the Southern Ocean. Significant removal of Ni and Cd was observed in the bloom and Zn was moderately correlated with reactive silicate (Si) indicating diatom control over the internal cycling of this metal. Higher concentrations of Zn and Cd were observed near the islands. Pb, Al, and Mn distributions also suggest small but significant atmospheric dust supply particularly in the northern region.

  5. Zn, Cd and Pb accumulation and arbuscular mycorrhizal colonisation of pennycress Thlaspi praecox Wulf. (Brassicaceae) from the vicinity of a lead mine and smelter in Slovenia

    International Nuclear Information System (INIS)

    Vogel-Mikus, Katarina; Drobne, Damjana; Regvar, Marjana

    2005-01-01

    Significant hyperaccumulation of Zn, Cd and Pb in field samples of Thlaspi praecox Wulf. collected from a heavy metal polluted area in Slovenia was found, with maximal shoot concentrations of 14590 mg kg -1 Zn, 5960 mg kg -1 Cd and 3500 mg kg -1 Pb. Shoot/root ratios of 9.6 for Zn and 5.6 for Cd show that the metals were preferentially transported to the shoots. Shoot bioaccumulation factors exceeded total soil Cd levels 75-fold and total soil Zn levels 20-fold, further supporting the hyperaccumulation of Cd and Zn. Eighty percent of Pb was retained in roots, thus indicating exclusion as a tolerance strategy for Pb. Low level colonisation with arbuscular mycorrhizal fungi (AMF) of a Paris type was observed at the polluted site, whereas at the non-polluted site Arum type colonisation was more common. To our knowledge this is the first report of Cd hyperaccumulation and AMF colonisation in metal hyperaccumulating T. praecox. - Thlaspi praecox Wulf. (Brassicaceae) is a newly discovered Cd, Zn and Pb hyperaccumulator able to form symbiosis with arbuscular mycorrhizal fungi

  6. 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

    International Nuclear Information System (INIS)

    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. - Colonisation of a Zn, Cd and Pb hyperaccumulator Thlaspi praecox with arbuscular mycorrhizal fungi resulted in improved nutrient and reduced Cd and Zn uptake

  7. 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.

  8. Heavy metals (Cd, Pb, Cu, Zn) in mudfish and sediments from three ...

    African Journals Online (AJOL)

    The percentage of uranium present in sediment samples (analysed by energy dispersive X-ray spectrometry) from the three dams was 9.0 % (SD 2.1%). In sediment it was found that cation exchange capacity measurements and the dolomitic hard water and high pH of the Mooi River water effectively \\'detoxified\\' Cd and Pb, ...

  9. Potential hyperaccumulation of Pb, Zn, Cu and Cd in endurant plants distributed in an old smeltery, northeast China

    Science.gov (United States)

    Cui, Shuang; Zhou, Qixing; Chao, Lei

    2007-01-01

    The absorption and accumulation of Pb, Zn, Cu and Cd in some endurant weed plant species that survived in an old smeltery in Liaoning, China, were systematically investigated. Potential hyperaccumulative characteristics of these species were also discussed. The results showed that metal accumulation in plants differed with species, tissues and metals. Endurant weed plants growing in this contaminated site exhibited high metal adaptability. Both the metal exclusion and detoxification tolerance strategies were involved in the species studied. Seven species for Pb and four species for Cd were satisfied for the concentration time level standard for hyperaccumulator. Considering translocation factor (TF) values, one species for Pb, seven species for Zn, two species for Cu and five species for Cd possessed the characteristic of hyperaccumulator. Particularly, Abutilon theophrasti Medic, exhibited strong accumulative ability to four heavy metals. Although enrichment coefficients of all samples were lesser than 1 and the absolute concentrations didn’t reach the standard, species mentioned above were primarily believed to be potential hyperaccumulators.

  10. Cd, Cu, Pb and Zn in clams and sediments from an impacted estuary by the oil industry in the southwestern Gulf of Mexico: concentrations and bioaccumulation factors.

    Science.gov (United States)

    Ruelas-Inzunza, J; Spanopoulos-Zarco, P; Páez-Osuna, F

    2009-12-01

    With the objective of estimating the temporal variation and bioavailability of Cd, Cu, Pb and Zn in Coatzacoalcos estuary, the biota-sediment accumulation factors (BSAF) were calculated. For this purpose, surficial sediments and clams from 14 selected sites were collected during three climatic seasons. In surficial sediments, highest levels of Cd and Cu were measured during the rainy season near to the industrial area of Minatitlan, while highest concentrations of Pb and Zn were registered during the windy season in sediments collected near to the industrial area of Coatzacoalcos. Considering all the sampling seasons and bivalve species, average metal concentrations followed the order Zn > Cu > Cd > Pb. BSAF ranged from 0.01 (Pb) in Corbicula fluminea during the hot season to 25.1 (Cd) in Polymesoda caroliniana during the windy season. BSAF of Cd, Cu and Zn were higher during the windy season; in the case of Pb, the dry season was the time when such figure was more elevated. It can be stated that Polymesoda caroliniana is a net accumulator of Cd and Zn and a weak accumulator of Pb for the studied estuary.

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

    International Nuclear Information System (INIS)

    Alexander, P.D.; Alloway, B.J.; Dourado, A.M.

    2006-01-01

    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

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

    Energy Technology Data Exchange (ETDEWEB)

    Alexander, P.D. [Royal Horticultural Society' s Garden, Wisley, Woking, Surrey GU23 6QB (United Kingdom)]. E-mail: paulalexander@rhs.org.uk; Alloway, B.J. [Department of Soil Science, School of Human and Environmental Sciences, University of Reading, P.O. Box 233, Reading RG6 6DW (United Kingdom); Dourado, A.M. [Royal Horticultural Society' s Garden, Wisley, Woking, Surrey GU23 6QB (United Kingdom)

    2006-12-15

    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.

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

    International Nuclear Information System (INIS)

    Audry, Stephane; Schaefer, Joerg; Blanc, Gerard; Jouanneau, Jean-Marie

    2004-01-01

    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 137 Cs 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 137 Cs 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 (I geo [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'' (I geo ∼ 4) and ''moderately to severely'' (I geo > 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

  14. 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.)

  15. Temporal changes in Hg, Pb, Cd and Zn environmental concentrations in the southern Baltic Sea sediments dated with 210Pb method

    Directory of Open Access Journals (Sweden)

    Tamara Zalewska

    2015-01-01

    Full Text Available The article presents data on heavy metal – Hg, Pb, Cd and Zn – distribution in the layers of marine sediments from the off-shore areas of the southern Baltic Sea: Gdańsk Deep, SE Gotland Basin and Bornholm Deep. Depth profiles of metal concentrations were converted to time-based profiles using the 210Pb dating method and verified by 137Cs distribution in the vertical profile. The linear sedimentation rates in the Gdańsk Deep and SE Gotland Basin are similar, 0.18 cm yr−1 and 0.14 cm yr−1, respectively, while the region of the Bornholm Deep is characterized by a greater sedimentation rate: 0.31 cm yr−1. Regarding anthropogenic pressure, Gdańsk Deep receives the largest share among the analyzed regions. The maximal metal concentrations detected in this area were Zn – 230 mg kg−1, Pb – 77 mg kg−1, Cd – 2.04 mg kg−1 and Hg – 0.27 mg kg−1. The least impact of anthropogenic pressure was noticeable in SE Gotland Basin. The combination of sediment dating with the analysis of vertical distribution of heavy metals in sediments benefited in the determination of target metal concentrations used in environmental status assessments. Reference values of heavy metal concentrations in marine sediments were determined as: Zn – 110 mg kg−1, Pb – 30 mg kg−1, Cd – 0.3 mg kg−1 and Hg – 0.05 mg kg−1 from the period of minor anthropogenic pressure. Basing on the determined indices: enrichment factor (EF, geoaccumulation indicator (Igeo and contamination factor (CF the status of marine environment was assessed regarding the pollution with heavy metals.

  16. 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)

    Baycu, Guelriz; Tolunay, Doganay; Ozden, Hakan; Guenebakan, Suereyya

    2006-01-01

    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

  17. Zn, Pb, Cr and Cd concentrations in fish, water and sediment from ...

    African Journals Online (AJOL)

    ADOWIE PERE

    Standard methods for examination of water and waste water, New York: American. Public Health Association Inc. Chien, L.C., Hung, L., Choang, K.Y., Yeh, C.Y.,. Meng, P.J., Shieh, M.J. and Han, B.C.. (2002).Daily intake of TBT, Cu, Zn, Cd and As for Fisherman in Taiwan. The Science of the. Total Environment, 285,177-185.

  18. Essential trace (Zn, Cu, Mn and toxic (Cd, Pb, Cr elements in the liver of birds from Eastern Poland

    Directory of Open Access Journals (Sweden)

    Komosa A.

    2012-01-01

    Full Text Available We have focused our study on the concentrations of essential heavy metals (Zn, Cu and Mn and non-essential trace metals (Pb, Cd and Cr in the livers of birds from Eastern Poland. The largest mean amount of Zn - as much as 279 mg/kg dry mass (d.m. - was found in mute swans. However, only in one of the analysed buzzard specimens the concentration of Zn, found to be 664 mg/kg d.m., exceeded the level indicative of poisoning for this element. Birds specializing in catching rodents accumulated Mn in their livers in a very narrow range of concentrations, around 5.0 mg/kg d.m. on average. The range of mean Mn concentrations (around 6.5 mg/kg d.m. was also found to be narrow for piscivorous birds. The highest mean levels of Pb were found in mute swans (2.7 mg/kg d.m., and the highest levels of Cd (2.0 mg/kg d.m. for rooks. Concentrations of total Cr above detection level were found in 22 specimens (53.7%, and concentration values were highest for rooks. Analyses showed that the concentrations of biogenic elements did not exceed the levels indicative of poisoning (except in one specimen. The study demonstrated that lead shots remain a hazard to water ecosystems. Pb, Cd and Cr levels in the livers of omnivorous and piscivorous species indicate the permanent presence of these elements in the environment and may confirm the thesis about the growing role of electronic waste, including metallic e-waste, in the emission of the total amount of contamination with these elements.

  19. Stabilization of Cd-, Pb-, Cu- and Zn-contaminated calcareous agricultural soil using red mud: a field experiment.

    Science.gov (United States)

    Wang, Yangyang; Li, Fangfang; Song, Jian; Xiao, Ruiyang; Luo, Lin; Yang, Zhihui; Chai, Liyuan

    2018-04-12

    Red mud (RM) was used to remediate heavy metal-contaminated soils. Experiments with two different dosages of RM added to soils were carried out in this study. It was found that soil pH increased 0.3 and 0.5 unit with the dosage of 3 and 5% (wt%), respectively. At the dosage of 5%, the highest stabilization efficiencies for Cd, Pb, Cu and Zn reached 67.95, 64.21, 43.73 and 63.73%, respectively. The addition of RM obviously transferred Cd from the exchangeable fraction to the residual fraction. Meanwhile, in comparison with the control (no RM added), it reduced 24.38, 49.20, 19.42 and 8.89% of Cd, Pb, Cu and Zn in wheat grains at the RM addition dosage of 5%, respectively. At the same time, the yield of wheat grains increased 17.81 and 24.66% at the RM addition dosage of 3 and 5%, respectively. Finally, the addition of RM did not change the soil bacterial community. These results indicate that RM has a great potential in stabilizing heavy metals in calcareous agricultural soils.

  20. Removal of Pb, Cu, Cd, and Zn Present in Aqueous Solution Using Coupled Electrocoagulation-Phytoremediation Treatment

    Directory of Open Access Journals (Sweden)

    Francisco Ferniza-García

    2017-01-01

    Full Text Available This study presents the results of a coupled electrocoagulation-phytoremediation treatment for the reduction of copper, cadmium, lead, and zinc, present in aqueous solution. The electrocoagulation was carried out in a batch reactor using aluminum electrodes in parallel arrangement; the optimal conditions were current density of 8 mA/cm2 and operating time of 180 minutes. For phytoremediation the macrophytes, Typha latifolia L., were used during seven days of treatment. The results indicated that the coupled treatment reduced metal concentrations by 99.2% Cu, 81.3% Cd, and 99.4% Pb, while Zn increased due to the natural concentrations of the plant used.

  1. 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.

  2. 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

  3. Enriquecimiento, disponibilidad y contaminación de metales traza (Cd, Cu, Pb y Zn) en sedimentos de lagunas urbanas de Concepción-Chile Enrichment, availability and contamination of trace metals (Cd, Cu, Pb and Zn) in sediments of urban lagoons in Concepción, Chile

    OpenAIRE

    Elizabeth González Sepúlveda; María Retamal Cifuentes; Valentina Medina Pedreros; Ramón Ahumada Bermúdez; José Neira Hinojosa

    2009-01-01

    Trace metals (Cd, Cu, Pb and Zn) enrichment, availability and contamination in superficial sediments of three interconnected urban lagoons localized in Concepción-Chile, were evaluated. According to the results of geochemical fracctionation analysis, Cu and Pb are rather associated with oxi-hydroxides, Cd is associated with exchangeable and carbonates fraction, while Zn is mainly associated with organic, oxi-hydroxides and residual fraction. The estimation of the availability percentages indi...

  4. Enhanced stabilization of Pb, Zn, and Cd in contaminated soils using oxalic acid-activated phosphate rocks.

    Science.gov (United States)

    Zhang, Zhuo; Guo, Guanlin; Wang, Mei; Zhang, Jia; Wang, Zhixin; Li, Fasheng; Chen, Honghan

    2018-01-01

    Phosphate amendments, especially phosphate rock (PR), are one of the most commonly used materials to stabilize heavy metals in contaminated soils. However, most of PR reserve consists of low-grade ore, which limits the efficiency of PR for stabilizing heavy metals. This study was to enhance the stabilization of heavy metals through improving the available phosphorous (P) release of PR by oxalic acid activation. Raw PR and activated PR (APR) were characterized by scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), X-ray powder diffraction (XRD), Brunauer-Emmett-Teller (BET) surface analysis, and laser diffraction to determine the changes of structure and composition of APR. The stabilization effectiveness of lead (Pb), zinc (Zn), and cadmium (Cd) in soils by APR was investigated through toxicity leaching test and speciation analysis. The results indicated that after treatment by oxalic acid, (1) the crystallinity of the fluorapatite phase of PR transformed into the weddellite phase; (2) the surface area of PR increased by 37%; (3) the particle size of PR became homogenized (20-70 μm); and (4) the available P content in PR increased by 22 times. These changes of physicochemical characteristics of PR induced that APR was more effective to transform soil heavy metals from the non-residual fraction to the residual fraction and enhance the stabilization efficiency of Pb, Zn, and Cd than PR. These results are significant for the future use of low-grade PR to stabilize heavy metals.

  5. STUDY ON PHYTO-EXTRACTION BALANCE OF ZN, CD AND PB FROM MINE-WASTE POLLUTED SOILS BY USING FESTUCA ARUNDINACEA AND LOLIUM PERENNE SPECIES

    Directory of Open Access Journals (Sweden)

    B. LIXANDRU

    2009-05-01

    Full Text Available Through the cultivation of tall fescue (Festuca arundinacea and of perennial ryegrass for two years on a chernozem type of soil, in the Banat's plain area we investigated the phyto-extraction potential of Zn, Cd and Pb. In the experimental plot it has been incorporated a quantity of 20 kg of mine-waste per square meter, in a mass ratio of 1:2,5. The mine-waste polluting "contribution" was of 1209 mg Zn / kg d.s., 4.70 mg Cd / kg d.s. and 188.2 mg Pb / kg d.s. The metals content in the soil was determined at the two moments of biomass harvesting, and through balance calculations we could establish the phyto-extraction efficiency of the two foragegrasses species. The obtained results indicate that Festuca arundinacea has an average phyto-extraction yield of 50% for Zn and Cd in the soil; in the case of an ionic excess of 3,5 to 4 times, the phyto-extraction efficiency is reduced, more obvious in the case of Pb (lead ions. The species Lolium perenne registers a yield of almost 92% in the process of phyto-extraction of Zn. The yield values for Cd si Pb are lower, but comparable with the control plot. Unlike Festuca arundinacea, the Lollium perenne species tolerates better the Cd and Pb ionic excess.

  6. Removal of Pb(II), Cd(II), Cu(II), and Zn(II) by hematite nanoparticles: effect of sorbent concentration, pH, temperature, and exhaustion.

    Science.gov (United States)

    Shipley, Heather J; Engates, Karen E; Grover, Valerie A

    2013-03-01

    Nanoparticles offer the potential to improve environmental treatment technologies due to their unique properties. Adsorption of metal ions (Pb(II), Cd(II), Cu(II), Zn(II)) to nanohematite was examined as a function of sorbent concentration, pH, temperature, and exhaustion. Adsorption experiments were conducted with 0.05, 0.1, and 0.5 g/L nanoparticles in a pH 8 solution and in spiked San Antonio tap water. The adsorption data showed the ability of nanohematite to remove Pb, Cd, Cu, and Zn species from solution with adsorption increasing as the nanoparticle concentration increased. At 0.5 g/L nanohematite, 100 % Pb species adsorbed, 94 % Cd species adsorbed, 89 % Cu species adsorbed and 100 % Zn species adsorbed. Adsorption kinetics for all metals tested was described by a pseudo second-order rate equation with lead having the fastest rate of adsorption. The effect of temperature on adsorption showed that Pb(II), Cu(II), and Cd(II) underwent an endothermic reaction, while Zn(II) underwent an exothermic reaction. The nanoparticles were able to simultaneously remove multiple metals species (Zn, Cd, Pb, and Cu) from both a pH 8 solution and spiked San Antonio tap water. Exhaustion experiments showed that at pH 8, exhaustion did not occur for the nanoparticles but adsorption does decrease for Cd, Cu, and Zn species but not Pb species. The strong adsorption coupled with the ability to simultaneously remove multiple metal ions offers a potential remediation method for the removal of metals from water.

  7. 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. Copyright © 2012 Elsevier Ltd. All rights reserved.

  8. Four thousand years of atmospheric Pb, Cd and Zn deposition recorded by the ombrotrophic peat bog of Penido Vello (northwestern Spain)

    Energy Technology Data Exchange (ETDEWEB)

    Martinez-Cortizas, A.; Pontevedra-Pombal, X.; Novoa-Munoz, J.C.; Garcia-Rodeja, E. [Universidad de Santiago de Compostila, Santiago de Compostela (Spain). Dept. de Edafologia y Quimica Agricola

    1997-12-01

    The Northwest Iberian Peninsula is a mid-latitude oceanic region with areas where different types of bogs are frequent or abundant. The ombrotrophic nature of some bogs make them suitable for the study of accumulation patterns of heavy metals. One of these bogs, Penido Vello, was sampled to a depth of 2.5 m and analyzed in detail for its physico-chemical properties and Pb, Zn and Cd concentrations. Ash and organic carbon content, Ca/Mg molar ratios and a number of other characteristics support an ombrotrophic interpretation of the core. Concentrations of Pb, Zn and Cd were measured, showing important variations in the core. While Zn and Cd are concentrated mainly in the upper sections of the core with minor changes with depth, the Pb profile shows significant peaks in the deeper layers suggesting pre-industrial atmospheric pollution. Enrichment factors (EFs) calculated by normalising to Al correlated well with those calculated by normalising to Ti. Maximum EFs are 33.56 and 52 for Pb, Zn and Cd respectively. While for Pb these values are comparable to those obtained by other authors, maximum Zn EFs are greater than those mentioned in the literature and may be attributed to the emissions of a nearby coal-burning power plant. At least for Pb the accumulation pattern suggests that atmospheric pollution can be dated back some 2800 years, and that pollution increased steadily since the Iron Age to reach considerably elevated levels, up to 5 times the `background`, during the Roman Empire. Changes in Pb emissions through times are in good accord with the prehistorical and historical record of the Iberian Peninsula. 54 refs., 8 figs., 1 tab.

  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. 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.

  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. Voltametrické stanovení Cu, Pb, Cd, Zn a Tl pomocí stříbrné pevné amalgamové elektrody

    Czech Academy of Sciences Publication Activity Database

    Josypčuk, Bohdan; Novotný, Ladislav

    2002-01-01

    Roč. 96, č. 9 (2002), s. 756-760 ISSN 0009-2770 Institutional research plan: CEZ:AV0Z4040901 Keywords : silver solid amalgam electrodes * voltammetry * Cu, Pb, Cd, Zn, Tl Subject RIV: CG - Electrochemistry Impact factor: 0.336, year: 2002

  13. Simultaneous determination of speciation parameters of Cu, Pb, Cd and Zn in model solutions of Suwannee River fulvic acid by pseudopolarography.

    Science.gov (United States)

    Chakraborty, Parthasarathi; Fasfous, Ismail I; Murimboh, John; Chakrabarti, Chuni L

    2007-05-01

    There is a growing awareness of the importance of quantitative determinations of speciation parameters of the trace metals Cu, Zn, Cd and Pb in aqueous samples containing chemically heterogeneous humic substances, especially when they are present together, interacting with one another and competing for specific binding sites of the humic substances. Such determinations require fundamental knowledge and understanding of these complex interactions, gained through basic laboratory-based studies of well-characterized humic substances in model solutions. Since the chemical heterogeneity of humic substances plays an important role in the thermodynamics (stability) and kinetics (lability) of trace metal competition for humic substances, a metal speciation technique such as pseudopolarography that can reveal the special, distinctive nature of metal complexation is required, and it was therefore used in this study. A comparison of the heterogeneity parameters (Gamma) for Zn(II), Cd(II), Pb(II) and Cu(II) complexes in model solutions of Suwannee River fulvic acid (SRFA) shows that GammaCd>GammaZn>GammaPb>GammaCu, suggesting that SRFA behaves as a relatively homogeneous complexant for Zn(II) and Cd(II), whereas it behaves as a relatively heterogeneous complexant for Pb(II) and an even more heterogeneous complexant for Cu(II) under the experimental conditions used. The order of values of log K* (from the differential equilibrium function, DEF) for the trace metals at pH 5.0 follow the sequence: log K*Cu>log K*Pb>log K*Zn>log K*Cd. These results are in good agreement with the literature values. The results of this work suggest the possibility of simultaneously determining several metals in a sample in a single experiment, and hence in a shorter time than required for multiple experiments.

  14. Sorption of Cr, Pb, Cu, Zn, Cd, Ni, and Co to nano-TiO2in seawater.

    Science.gov (United States)

    Bożena, Graca; Zakrzewska, Danuta; Szymczycha, Beata

    2018-01-01

    In this study, the role of nanoparticles in complex aqueous matrices such as the Baltic Sea was investigated in batch-mode experiments in which titanium dioxide nanoparticles (nano-TiO 2 ) were tested for their ability to remove heavy metals (Cr, Pb, Cu, Zn, Cd, Ni, Co) from multicomponent spiked and non-spiked Baltic Sea water. The experimental data were analyzed using different isotherms (Langmuir, Freundlich, Dubinin-Kaganer-Radushkevich (DKR)) and models (pseudo-first-order and pseudo-second-order models, the double-exponential model, and the Weber-Morris model). The equilibria and kinetic investigations showed that metal sorption to nano-TiO 2 occurs in a two-step, multilayer process and that there is strong competition for sorption sites. The results of the DKR isotherm and dilution experiment indicated weak electrostatic bonds, except for Pb. The distribution coefficient values (1.8 × 10 3 to 2.8 × 10 5 ml g -1 ) were consistent with the good sorbent properties of nano-TiO 2 and supported the use of the particles in seawater purification technologies. However, metal-enriched nano-TiO 2 may also act as an effective carriers of metals to marine sediments, which could increase their availability to benthic organisms.

  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)

    Brown, Sally; Christensen, Barbara; Lombi, Enzo; McLaughlin, Mike; McGrath, Steve; Colpaert, Jan; Vangronsveld, Jaco

    2005-01-01

    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 NH 4 NO 3 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. An inter-laboratory study to test the ability of amendments to reduce the availability of Cd, Pb, and Zn in situ

    Energy Technology Data Exchange (ETDEWEB)

    Brown, Sally [Box 352100 University of Washington, Seattle, WA 98195 (United States)]. E-mail: slb@u.washington.edu; Christensen, Barbara [Box 352100 University of Washington, Seattle, WA 98195 (United States); Lombi, Enzo [CSIRO Land and Water PMB, 2 Glen Osmond, Adelaide, South Australia (Australia)]. E-mail: enzo.lombi@csiro.au; McLaughlin, Mike [CSIRO Land and Water PMB, 2 Glen Osmond, Adelaide, South Australia (Australia)]. E-mail: mike.mclaughlin@csiro.au; McGrath, Steve [Rothamsted Research, Harpenden, Herts AL5 2JQ (United Kingdom)]. E-mail: steve.mcgrath@bbsrc.ac.uk; Colpaert, Jan [Limburgs Universitair, Centrum Universitaire Campus, Building D, BE 3590 Diepenbeek (Belgium); Vangronsveld, Jaco [Limburgs Universitair, Centrum Universitaire Campus, Building D, BE 3590 Diepenbeek (Belgium)]. E-mail: jvangron@luc.ac.be

    2005-11-15

    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{sup -1} C) and total Cd, Pb, and Zn concentrations of 92, 5022, and 18 532 mg kg{sup -1}, respectively. Amendments included lime, phosphorus (P), red mud (RM), cyclonic ashes (CA), biosolids (BIO), and water treatment residuals (WTR). Both soil solution and NH{sub 4}NO{sub 3} 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{sup -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.

  17. Zróżnicowanie zawartości Cd, Pb, Zn i Cu w biomasie wykorzystywanej na cele energetyczne

    Directory of Open Access Journals (Sweden)

    Artur Szwalec

    2016-12-01

    Full Text Available Spalaniu węgla kamiennego, na którym oparta jest Polska energetyka, towarzyszy współspalanie biomasy. Wykorzystanie tego odnawialnego źródła energii może nieść również zagrożenia wynikające z potencjalnego zanieczyszczenia biomasy metalami ciężkimi. Celem pracy była ocena zróżnicowania zawartość Cd, Pb, Zn i Cu w różnych rodzajach biomasy wykorzystywanej do produkcji energii elektrycznej w jednej z polskich elektrowni. Biomasę mineralizowano na sucho. Zawartości analizowanych pierwiastków oznaczono metodą FAAS. Rodzaj analizowanej biomasy miał wpływ na zwartość badanych metali. Zawartości kadmu, ołowiu, cynku w poszczególnych rodzajach biomasy cechowały się dużym zróżnicowaniem, współczynnik zmienności wyniósł odpowiednio 92% (Cd, 89% (Pb i 80% (Cu. Zmienność zawartość cynku była średnio zróżnicowana (V = 37%. Zawartości kadmu w pelecie ze słomy i brykiecie drzewnym oraz zawartości cynku i miedzi w wytłokach z oliwek, pelecie ze słonecznika, pelecie ze słomy i brykiecie drzewnym przekraczały wartości typowe dla tych rodzajów biomasy zamieszczone w normie.

  18. Wood-derived-biochar combined with compost or iron grit for in situ stabilization of Cd, Pb, and Zn in a contaminated soil.

    Science.gov (United States)

    Oustriere, Nadège; Marchand, Lilian; Rosette, Gabriel; Friesl-Hanl, Wolfgang; Mench, Michel

    2017-03-01

    In situ stabilization of Cd, Pb, and Zn in an Austrian agricultural soil contaminated by atmospheric depositions from a smelter plant was assessed with a pine bark chip-derived biochar, alone and in combination with either compost or iron grit. Biochar amendment was also trialed in an uncontaminated soil to detect any detrimental effect. The pot experiment consisted in ten soil treatments (% w/w): untreated contaminated soil (Unt); Unt soil amended with biochar alone (1%: B1; 2.5%: B2.5) and in combination: B1 and B2.5 + 5% compost (B1C and B2.5C), B1 and B2.5 + 1% iron grit (B1Z and B2.5Z); uncontaminated soil (Ctrl); Ctrl soil amended with 1 or 2.5% biochar (CtrlB1, CtrlB2.5). After a 3-month reaction period, the soil pore water (SPW) was sampled in potted soils and dwarf beans were grown for a 2-week period. The SPW Cd, Pb, and Zn concentrations decreased in all amended-contaminated soils. The biochar effects increased with its addition rate and its combination with either compost or iron grit. Shoot Cd and Zn removals by beans were reduced and shoot Cd, Pb, and Zn concentrations decreased to common values in all amended soils except the B1 soil. Decreases in the SPW Cd/Pb/Zn concentrations did not improve the root and shoot yields of plants as compared to the Ctrl soil.

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

    International Nuclear Information System (INIS)

    Raimundo, J.; Vale, C.; Duarte, R.; Moura, I.

    2008-01-01

    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

  20. Toxic metals (Pb and Cd) and their respective antagonists (Ca and Zn) in infant formulas and milk marketed in Brasilia, Brazil.

    Science.gov (United States)

    De Castro, Clarissa S P; Arruda, Andréa F; Da Cunha, Leandro R; SouzaDe, Jurandir R; Braga, Jez W B; Dórea, José G

    2010-11-01

    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. 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.

  2. 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.

  3. 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

    2009-05-01

    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.

  4. Highly enhanced photocurrent of novel quantum-dot-co-sensitized PbS-Hg/CdS/Cu:ZnO thin films for photoelectrochemical applications

    Energy Technology Data Exchange (ETDEWEB)

    Gohel, Jignasa V.; Jana, A.K.; Singh, Mohit [Sardar Vallabhbhai National Institute of Technology, Chemical Engineering Department, Surat, Gujarat (India)

    2017-08-15

    A novel quantum-dot-co-sensitized PbS-Hg/CdS/Cu:ZnO thin films synthesized by low-cost process. The properties of ZnO are also enhanced by doping and co-doping. It is also compared with quantum-dot co-sensitization. Optical properties, crystal structure, morphology, and photocurrent are characterized by UV-Vis spectroscopy, XRD, SEM, and solar simulator, respectively. The bandgap is interestingly reduced highly to 2.6 eV for Ag co-doped Cu:ZnO. It is unprecedentedly reduced to 2.1 eV and even 1.97 eV for CdS and PbS-Hg QD-sensitized thin films, respectively. An exceptionally enhanced photocurrent of 17.1 mA/cm{sup 2} is achieved with PbS-Hg-co-sensitized CdS-sensitized Cu:ZnO thin film. This is an excellent achievement, which highly supports the potential of low-cost solar conversion. (orig.)

  5. 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.

  6. The transfer and fate of Pb from sewage sludge amended soil in a multi-trophic food chain: a comparison with the labile elements Cd and Zn.

    Science.gov (United States)

    Dar, Mudasir Irfan; Khan, Fareed Ahmad; Green, Iain D; Naikoo, Mohd Irfan

    2015-10-01

    The contamination of agroecosystems due to the presence of trace elements in commonly used agricultural materials is a serious issue. The most contaminated material is usually sewage sludge, and the sustainable use of this material within agriculture is a major concern. This study addresses a key issue in this respect, the fate of trace metals applied to soil in food chains. The work particularly addresses the transfer of Pb, which is an understudied element in this respect, and compares the transfer of Pb with two of the most labile metals, Cd and Zn. The transfer of these elements was determined from sludge-amended soils in a food chain consisting of Indian mustard (Brassica juncea), the mustard aphid (Lipaphis erysimi) and a predatory beetle (Coccinella septempunctata). The soil was amended with sludge at rates of 0, 5, 10 and 20 % (w/w). Results showed that Cd was readily transferred through the food chain until the predator trophic level. Zn was the most readily transferred element in the lower trophic levels, but transfer to aphids was effectively restricted by the plant regulating shoot concentration. Pb had the lowest level of transfer from soil to shoot and exhibited particular retention in the roots. Nevertheless, Pb concentrations were significantly increased by sludge amendment in aphids, and Pb was increasingly transferred to ladybirds as levels increased. The potential for Pb to cause secondary toxicity to organisms in higher trophic levels may have therefore been underestimated.

  7. CONTRIBUTIONS TO THE STUDY OF HEAVY METALS DISTRIBUTION (Zn, Pb, Cd, Bi, Cu IN SOME SOILS FROM GIURGEU MOUNTAINS

    Directory of Open Access Journals (Sweden)

    D. Bulgariu

    2005-10-01

    Full Text Available In this paper are presented the results of mineralogical and geochemical studies, realized for few soils from Giurgeu Mountains, which have as main purpose the distribution and mobility interpretation of minor elements (Cd, Cu, Pb, Zn, Bi in studied soil samples. The determination of fixed fractions and mobile fractions weight, at total contents of studied elements, and relative association of these elements with main mineral and organic components of soil samples, was realized on the basis of results obtained by sequential solid/ liquid extraction. The same, we try to use the correlation establish between metallic ions contents, as indicators of mineral paragenesis (the genetic type and formation conditions. The obtained results are agree with the results of similar studies from literature and they, underline of some interesting aspects about of distribution and migration of heavy metals in soils: (1 exist of some selectivity in heavy metals distribution in mineral components from soils, correlated with reciprocals geochemical affinities between speciation forms of metals and mineral components, in a given pedogeochemical context; (2 the heavy metals distribution between solid phases and soil solution are realized in competitive regime, and the inter-phases equilibrium evolution are thermodynamic and kinetics controlled by the solid/ liquid interfaces processes; (3 the fast elementary processes and local fluctuations of physic-chemical parameters are the main factors which controlled the inter-phases transfer ratio and the evolution direction of equilibriums of heavy metals distribution.

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

    International Nuclear Information System (INIS)

    Ahmed, R.; Viqar-un-Nisa; Tanwir, R.

    1988-09-01

    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)

  9. Pollution of soils (Pb, Cd, Cr, Zn, Cu, Ni) along the ring road of Wrocław (Poland)

    Science.gov (United States)

    Hołtra, Anna; Zamorska-Wojdyła, Dorota

    2017-11-01

    The concentrations of metallic pollution in soils and plants along the ring road of Wrocław, Poland, have been determined. Environmental samples were collected from the surface layer of the profile within 2-3 m from the edge of the road. The analysis of metals (Pb, Cd, Cr, Zn, Cu and Ni) has been carried out through FAAS and GFAAS methods. The mineralizates of soils and plants were prepared in HNO3, 65% supra pure, using the Microwave Digestion System. The pH and conductivity of the soil solutions were measured to evaluate their active and exchangeable acidity and the salinity of the soils. The index of the enrichment of soils in metals (Wn) and the bioaccumulation coefficient (WB) have been determined. Also, histograms of the frequency of the occurrence of metals in the environmental samples and the Pearson's correlation coefficients were presented. The results of metal concentrations in soils were compared to the geochemical background in uncontaminated soils of Poland. The assessment of the results in the soils was also made relative to the standard, according to the Polish Ministry of Environment Regulation from September 1st, 2016. During the assessment of the bioaccumulation coefficients of metals in plants a reference was made to the content of undesirable substances in feed in agreement with the Polish Ministry of Agriculture and Rural Development Regulation from January 23rd, 2007.

  10. Assessing comparative terrestrial ecotoxicity of Cd, Co, Cu, Ni, Pb, and Zn: The influence of aging and emission source

    International Nuclear Information System (INIS)

    Owsianiak, Mikołaj; Holm, Peter E.; Fantke, Peter; Christiansen, Karen S.; Borggaard, Ole K.; Hauschild, Michael Z.

    2015-01-01

    Metal exposure to terrestrial organisms is influenced by the reactivity of the solid-phase metal pool. This reactivity is thought to depend on the type of emission source, on aging mechanisms that are active in the soil, and on ambient conditions. Our work shows, that when controlling for soil pH or soil organic carbon, emission source occasionally has an effect on reactivity of Cd, Co, Cu, Ni, Pb and Zn emitted from various anthropogenic sources followed by aging in the soil from a few years to two centuries. The uncertainties in estimating the age prevent definitive conclusions about the influence of aging time on the reactivity of metals from anthropogenic sources in soils. Thus, for calculating comparative toxicity potentials of man-made metal contaminations in soils, we recommend using time-horizon independent accessibility factors derived from source-specific reactive fractions. - Highlights: • We found an effect of source on reactivity of anthropogenic metals in soils. • The influence of aging on reactivity of anthropogenic metals was not consistent. • We recommend including source and disregarding aging in calculation of CTPs values. - Improving current life cycle inventory (LCI) and life cycle impact assessment (LCIA) practice in terrestrial ecotoxicity assessment of metals.

  11. Immobilization of heavy metals (Pb, Cu, Cr, Zn, Cd, Mn) in the mineral additions containing concrete composites.

    Science.gov (United States)

    Giergiczny, Zbigniew; Król, Anna

    2008-12-30

    The presented work determines the level of heavy metals (Pb+2, Cu+2, Zn+2, Cr+6, Cd+2, Mn+2) immobilization in the composites produced using Ordinary Portland Cement (OPC) as well as of binders containing large amount of mineral additives in its composition-siliceous fly ash (FA), fluidized bed combustion ash (FFA) and ground granulated blast furnace slag (GGBFS). Heavy metals were introduced to cementitious materials in the form of soluble salts as well as components of hazardous wastes (medical ash, metallurgical dust). It has been stated, that the level of heavy metals immobilization is combined with composites composition. Majority of analyzed heavy metals, added to binders' composition in the form of heavy metal salts achieves high level of immobilization, in mortar based on binder with 85% GGBFS and 15% OPC. The lowest immobilization level was reached for chromium Cr+6 added to hardening mortars as Na2Cr2O72H2O. The level ranges from 85.97% in mortars made on blended binder (20% OPC, 30% FFA and 50% GGBFS) to 93.33% in mortar produced on OPC. The increase of the so-called immobilization degree with time of hardened material maturing was found. This should be attributed to the pozzolanic or pozzolanic/hydraulic properties of components used; their effect on microstructure of hardened material is also important. Mineral additions enter the hydration reactions in the mixtures and favor the formation of specific microstructure promoting the immobilization of hazardous elements.

  12. 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)

    Parra, Juan Pablo; Espinosa, Luisa Fernanda

    2008-01-01

    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

  13. 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.

  14. Bioavailability and Variability of Cd, Pb, Zn, and Cu Pollution in Soft Tissues and Shell of Saccostrea cucullata Collected from the Coast of Qeshm Island, Persian Gulf, Iran

    Directory of Open Access Journals (Sweden)

    Ali Kazemi

    2016-07-01

    Full Text Available Background: Marine pollution is a global environmental problem that its monitoring by ideal biomonitors is of great importance. Marine organisms, especially mussels, have the ability to accumulate metals from the environment; they can be considered as a biomonitoring agent. Methods: In this study, concentrations of heavy metals were measured in Saccostrea cucullata collected from seven sites on Qeshm Island's Coast. To achieve a digesting sample, each soft tissue was obtained and each of the shell homogeneous powders, 0.8 g and 1 g, respectively, were mixed with 10 mL HNO3 (69% and poured into a PTFE digestion vessel. The prepared samples were evaluated for Cd, Cu, and Zn by using a flame AAS Model 67OG and for Pb by using a graphite furnace AAS. Results: The distributions of metals between soft tissues and shells were compared in each sampling site. For seven sites, Cd, Zn, and Cu levels in soft tissues were higher than in the shells, but Pb level was higher in the shells than in the soft tissues. In addition, the results indicated the coefficient of variation (CV in the soft tissues was lower than the shells for Cd, and in the shells lower than the soft tissues for Pb, whereas the CV values were different in both the soft tissues and shells for Zn and Cu. Conclusion: The results of this study support using these materials in S. cucullata for biomonitoring. Shells are appropriate for monitoring Pb contamination, and the soft tissues are more apt for monitoring Cd, Zn, and Cu contamination.

  15. 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.

  16. Determination of Cd, Pb, Zn and Cu in Sediment Compartments by Sequential Extraction and Isotope Dilution Inductively Coupled Plasma Mass Spectrometry (ID-ICP-MS

    Directory of Open Access Journals (Sweden)

    Gardolinski Paulo C. F. C.

    2002-01-01

    Full Text Available Trace concentrations of Cd, Cu, Pb and Zn in four different sediment fractions extracted in sequence were determined by isotope dilution inductively coupled mass spectrometry (IDICPMS. The metals from each fraction were extracted following the sequential extraction procedure recommended by the Bureau Commun de Référence (BCR of the Commission of the European Communities. As an alternative to external calibration, the elements were quantified by spiking the extracted solutions with 112Cd, 63Cu, 208Pb and 66Zn and application of isotope dilution. The proposed approach was applied to a sample collected from a lake and two standard reference materials, NIST2704 river sediment from the National Institute of Standards & Technology and the BCR-277 estuarine sediment. Detection limits, for each extracted solution, varied from 0.31 to 0.53 mug L¹ for Cd, 0.92 to 2.9 mug L¹ for Cu, 0.22 to 1.1 mug L¹ for Pb and 1.3 to 7.6 mug L¹ for Zn. The sum of the metals concentration in the different fractions was compatible with 95% confidence level found amounts obtained with complete digestion of the samples and with the certified values of the standard reference materials.

  17. Study on accumulation of Fe, Pb, Zn, Ni and Cd in Nerita lineata and Thais bitubercularis from Tanjung Harapan and Teluk Kemang, Malaysia.

    Directory of Open Access Journals (Sweden)

    Tengku

    2017-01-01

    Full Text Available The presence of Cd, Cu, Zn, Ni, Fe, Al, Zn, Mn, Cr, and Sn were attributed to metal industries. Cu contamination was associated with piggery industry. Shipping activities contribute to elevated levels of Pb, Cu and As. Elevated levels of metals in the sediments are attributed to anthropogenic activities. Samples were collected in April 2012 and analysed using inductively coupled plasma mass spectrometry (ICP-MS. Fe is the most abundant metal in the tissue and shell compared to the rest of the metals. The concentrations of heavy metals in the soft tissues of Nerita lineata taken from Tanjung Harapan follow this order: Fe > Zn > Ni > Cu > Cd while in Thais bitubercularis, the metal concentrations were higher following the order of Fe > Zn > Cu > Ni > Cd. The samples taken from Teluk Kemang were higher and exhibited different trend for both organisms. Results from this study are useful for further exploration of Thais bitubercularis as accumulators of Cu, Cd, and Zn. For recommendation, more studies on monitoring the concentration level of heavy metals in marine environment should be done regularly and increase numbers of samples use to biomonitor the heavy metals in marine environment as it is important to have information or data regarding the quality of marine environment in order to control pollution such as water pollution from being contaminated with heavy metals. This is essential as the pollutants emit in the marine environment may affect marine lives as well as human’s health

  18. Effects of Crop Straw Returning with Lime on Activity of Cu, Zn, Pb and Cd in Paddy Soil

    Directory of Open Access Journals (Sweden)

    NI Zhong-ying

    2017-05-01

    Full Text Available Crop straw returning is an important measure for increasing soil carbon fixation and soil fertility in China, but it also may result in some risk of raising activity of heavy metals in the soil. In order to understand the effects of different sources of crop straw on heavy metals activity in soil with different pollution levels, and to take appropriate measures to prevent the activation of heavy metals in the soil, both pot and field experiments were carried out to study the effects of crop straw returning with lime on activity of Cu, Zn, Pb and Cd in paddy soil. The experiments were carried out in the soils with both light and heavy pollution of heavy metals. In the pot experiment, three straws, including rice straw with heavy pollution of heavy metals, rice straw with light pollution of heavy metals, and rape straw with light pollution of heavy metals, were tested. Two dosages of lime(0 kg·hm-2 and 750 kg·hm-2were applied. Field experiment had three treatments, ie., control without application of straw and lime, straw returning and straw returning + lime. Soil available heavy metals, accumulation of heavy metals in rice grain, and chemical forms of soil heavy metals were dynamical monitored. The results showed that crop straw returning increased significantly the concentrations of dissolved organic carbon and water soluble heavy metals in paddy soils at the early stage of experiment (in first 20 days. The increase in water soluble heavy metals in the soil with heavy pollution of heavy metals was most obvious as compared with the control treatment. After 60th day of the experiment, the effects of straw returning on the activity of heavy metals in the soil decreased gradually with the time, and became no obvious. The concentrations of water soluble heavy metals in the soil treated with rape straw was generally lower than that of rice straw, while those in the soil treated with heavy pollution of rice straw was higher than low pollution of rice

  19. Disponibilidade e fracionamento de Cd, Pb, Cu e Zn em função do pH e tempo de incubação com o solo Availability and fractionation of Cd, Pb, Cu, AND Zn in soil as a function of incubation time and pH

    Directory of Open Access Journals (Sweden)

    Évio Eduardo Chaves de Melo

    2008-06-01

    Full Text Available O pH e o tempo de contato influenciam a distribuição dos metais entre frações do solo e a eficiência da fitoextração. Objetivou-se, neste trabalho estudar a disponibilidade dos metais Cd, Pb, Cu e Zn para a fitoextração, bem como suas redistribuições no solo, em função do tempo de incubação em solo com e sem calagem. O solo recebeu Cd, Pb, Cu e Zn nas doses 20, 150, 100 e 150 mg kg-1, respectivamente, na forma de sal solúvel. As amostras foram incubadas por 210, 180, 150, 120, 90, 60, 30 e 0,5 dia. Terminada a incubação, mucuna preta (Stizolobium aterrimum Piper & Tracy foi cultivada por 30 dias. EDTA (10 mmol kg-1 foi aplicado sete dias, antes da coleta das plantas. As amostras de solo foram submetidas à extração química e fracionada. A concentração de metais pesados e a calagem afetaram a produção de matéria seca da parte aérea e da raiz. Em solos sem calagem, o aumento da solubilidade dos metais aumentou a fitoextração de Cd e Zn, mesmo sem aplicação do EDTA. A aplicação do EDTA ao solo com calagem mostrou-se eficiente para a fitoextração de Pb e Cu. A calagem reduziu os teores disponíveis de Cd, Pb, Cu e Zn. A calagem provocou redução nos teores de Cd, Pb, Cu e Zn trocáveis e aumento nas frações matéria orgânica, óxidos de ferro amorfo e cristalino.It is known that pH and incubation time influence the distribution of metals into soil fractions and therefore affect phytoextraction. Taking this in account, the aim of this work was to study the fractionation and availability of heavy metals for phytoextraction, as a function of incubation period in soils with or without liming. The soil samples were applied to Cd, Pb, Cu, and Zn at concentrations of 20, 150, 100, and 150 mg kg-1, respectively, in the form of soluble salt. The samples were kept incubated for high incubation periods: 210, 180, 150, 120, 90, 60, 30, and 0,5 day. After that, velvetbean (Stizolobium aterrimum Piper & Tracy was cultivated

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

    Science.gov (United States)

    Brown, Sally; Christensen, Barbara; Lombi, Enzo; McLaughlin, Mike; McGrath, Steve; Colpaert, Jan; Vangronsveld, Jaco

    2005-11-01

    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%.

  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. Enriquecimiento, disponibilidad y contaminación de metales traza (Cd, Cu, Pb y Zn en sedimentos de lagunas urbanas de Concepción-Chile Enrichment, availability and contamination of trace metals (Cd, Cu, Pb and Zn in sediments of urban lagoons in Concepción, Chile

    Directory of Open Access Journals (Sweden)

    Elizabeth González Sepúlveda

    2009-01-01

    Full Text Available Trace metals (Cd, Cu, Pb and Zn enrichment, availability and contamination in superficial sediments of three interconnected urban lagoons localized in Concepción-Chile, were evaluated. According to the results of geochemical fracctionation analysis, Cu and Pb are rather associated with oxi-hydroxides, Cd is associated with exchangeable and carbonates fraction, while Zn is mainly associated with organic, oxi-hydroxides and residual fraction. The estimation of the availability percentages indicate that Cu is the most mobile metal and the less mobile is the Cd. An evaluation of the geo-accumulation index and urban industrial pollution allowed to classify the studied zone as moderately to highly contaminated.

  3. 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.

  4. Atmospheric deposition of Pb, Cu, Ni, As, Sb, V, Cr, Co, Cd and Zn recorded in the Misten peat bog (Hautes-Fagnes, Belgium) during the Industrial Revolution

    Science.gov (United States)

    Allan, M.; Le Roux, G.; De Vleeschouwer, F.; Mattielli, N.; Fagel, N.

    2012-04-01

    A 40 cm peat core was studied from ombrotrophic bog in Western Europe (Misten bog, Hautes-Fagnes, Belgium). Trace metal and metalloid content (TM) and Pb isotopes were analysed by Q-ICP-MS and MC-ICP-MS, respectively. We focused our attention to a selected number of TM according to their specific enrichment (i.e. Pb, Cu, Ni, As, Sb, Cr, Co, V, Cd and Zn). Our aims were: 1) to investigate TM mobility; 2) to determine TM accumulation rates and 3) to link TM accumulation rates with established histories of anthropogenic atmospheric emission. According to 210Pb and 14C data the studied peat core section covered the last two centuries. The general agreement in TM concentration and flux profiles suggested that all TM (except Zn and Cd), were immobile in the Misten peat bog. The temporal increase of TM fluxes between the inception of the Industrial Revolution and the present vary by a factor of 5 to 50 according to TM. The maximum fluxes of TM were found between 1991 and 1995 AD. The coal consumption and metallurgical activities were the predominant source of pollution. The historical TM profiles in the Misten peat profile are in agreement with other European records, reflecting the influence of regional European pollution.

  5. Effects of cement or lime on Cd, Co, Cu, Ni, Pb, Sb and Zn mobility in field-contaminated and aged soils.

    Science.gov (United States)

    Hale, Beverley; Evans, L; Lambert, R

    2012-01-15

    Cement or lime can be used to treat trace element contaminated soils, reducing their mobility due to increased soil pH which enhances precipitation and adsorption, and also due to pozzolanic reactions and cementation. In the present work, an alkaline and an acidic soil both containing Cd, Co, Cu, Ni, Pb, Sb and Zn from either geogenic or geogenic and anthropogenic origin were treated with cement or calcium hydroxide. Soils were then extracted with dilute HNO(3) or NaOH solution of different concentrations to obtain extracts of different pH (pH 4-12). In untreated soils, Co, Cu, Ni and Pb in solutions were detected at alkaline pH. The addition of cement or Ca(OH)(2) reduced the mobility of every trace element at high pH, but enhanced the mobility of Cd, Co, Cu, Ni, Pb and Zn at low pH. Metal mobilisation at high pH was observed for Cu in the acidic soil due to the liberation of dissolved organic matter. Below pH 6, Sb mobility was lower in the cement-treated soil compared to the untreated soil, but the same in the Ca(OH)(2) treated soil as in the control soil. Comparison with theoretical trace element precipitates suggested that the mobility of trace elements is likely reduced at high pH by encapsulation and immobilisation within the cement matrix rather then precipitation. Copyright © 2011 Elsevier B.V. All rights reserved.

  6. Beneficial effects of tobacco biochar combined with mineral additives on (im)mobilization and (bio)availability of Pb, Cd, Cu and Zn from Pb/Zn smelter contaminated soils.

    Science.gov (United States)

    Lahori, Altaf Hussain; Zhang, Zengqiang; Guo, Zhanyu; Li, Ronghua; Mahar, Amanullah; Awasthi, Mukesh Kumar; Wang, Ping; Shen, Feng; Kumbhar, Farhana; Sial, Tanveer Ali; Zhao, Junchao; Guo, Di

    2017-11-01

    The efficacy of tobacco biochar (TB) alone and in combined with mineral additives: Ca-hydroxide (CH), Ca-bentonite (CB) and natural zeolite (NZ), on immobilization of Pb, Cd, Cu and Zn, via reduce its (bio) availability to plants were investigated. The soils were collected from Tongguan contaminated (TG-C), Fengxian heavily contaminated (FX-HC) and Fengxian lightly contaminated (FX-LC) fields, Shaanxi province, China. The contaminated top soils were treated with low-cost amendments with an application rate of 1% and cultivated by Chinese cabbage (Brassica campestris L.) under greenhouse condition. Results showed that the all amendments (p < 0.05) potentially maximum reduced the DTPA-extractable Pb 82.53, Cd 31.52 and Cu 75.0% with TB + NZ in FX-LC soil, while in case of Zn 62.21% with TB + CH in FX-HC soil than control. The addition of amendments clearly increased dry biomass of Brassica campestris L. as compared with un-amended treatment (except TB + CH). Furthermore, these amendments markedly increased the uptake by plant shoot viz, Cd 10.51% with TB alone and 11.51% with TB + CB in FX-HC soil, similarly in FX-LC Cd increased 5.15% with TB + CH and 22.19% with TB + NZ, respectively. In same trend the Cu uptake in plant shoot was 19.30% with TB + CH in TG-C, whereas 43.90 TB + CH and 19.24% with TB + NZ in FX-LC soil. On the other hand as compared to control Cu accumulation in plant root was observed by TB, TB + CH and TB + CB treatments, while maximum uptake was 62.41% with TB + CH in TG-C soil. Consequently, except TB + CH treatment the chlorophyll content potentially increased in all amendment than control treatment, because of changes in soil EC, pH but increased CEC values after application of amendments. The results of this pot experiment are promising but they will further need to be confirmed with long-term field experiments. Copyright © 2017 Elsevier Inc. All rights reserved.

  7. Assessment of metal pollution in a former mining area in the NW Tunisia: spatial distribution and fraction of Cd, Pb and Zn in soil.

    Science.gov (United States)

    Othmani, Mohamed Ali; Souissi, Fouad; Durães, Nuno; Abdelkader, Moussi; da Silva, Eduardo Ferreira

    2015-08-01

    This study aims to evaluate the impact of the former mining Touiref district (NW Tunisia) on the spatial distribution of metal contamination. In order to characterize the metal content of the tailings and to assess how far the soils from the district could be impacted by metals, a sampling campaign was conducted. According to the spatial distribution concentration maps of potential toxic elements (PTE), the highest concentrations occur near the flotation tailings and in mining facilities and decrease abruptly with distance. These results confirm that wind is the main agent capable of dispersing metals in a W-E direction, with concentrations exceeding the standards of soil quality for Cd, Pb and Zn over several hundred metres away from the source, facilitated by the small-size fraction and low cohesion of tailings particles. Chemical fractionation showed that Pb and Cd were mainly associated with the acid-soluble fraction (carbonates) and Fe-(oxy) hydroxides, while Zn was mainly associated with Fe-(oxy) hydroxides but also with sulphides. Thus, the immobilization of metals in solution may be favoured by the alkaline conditions, promoted by carbonates dissolution. However, being carbonate important-bearing phases of Cd and Pb (but also for Zn), the dissolution facility of these minerals may enhance the release of metals, particularly far away from the mine where the physicochemical conditions can be different. Also, the metal uptake by plants in these alkaline conditions may be favoured, especially if secondary phases with high sorption ability are reduced at this site. A remediation plan to this area is needed, with particularly attention in the confinement of the tailings.

  8. 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).

  9. Geographical and pedological drivers of distribution and risks to soil fauna of seven metals (Cd, Cu, Cr, Ni, Pb, V and Zn) in British soils

    Energy Technology Data Exchange (ETDEWEB)

    Spurgeon, David J. [Centre for Ecology and Hydrology, Monks Wood, Abbots Ripton, Huntingdon, Cambridgeshire PE28 2LS (United Kingdom)], E-mail: dasp@ceh.ac.uk; Rowland, Philip; Ainsworth, Gillian [Centre for Ecology and Hydrology, Lancaster, Bailrigg, Lancaster LA1 4AP (United Kingdom); Rothery, Peter; Long, Sara [Centre for Ecology and Hydrology, Monks Wood, Abbots Ripton, Huntingdon, Cambridgeshire PE28 2LS (United Kingdom); Black, Helaina I.J. [Soils Group, The Macaulay Institute, Craigiebuckler, Aberdeen AB15 8QH (United Kingdom)

    2008-05-15

    Concentrations of seven metals were measured in over 1000 samples as part of an integrated survey. Sixteen metal pairs were significantly positively correlated. Cluster analysis identified two clusters. Metals from the largest (Cr, Cu, Ni, V, Zn), but not the smallest (Cd, Pb) cluster were significantly negatively correlated with spatial location and soil pH and organic matter content. Cd and Pb were not correlated with these parameters, due possibly to the masking effect of recent extensive release. Analysis of trends with soil properties in different habitats indicated that general trends may not necessarily be applicable to all areas. A risk assessment indicated that Zn poses the most widespread direct risk to soil fauna and Cd the least. Any risks associated with high metal concentrations are, however, likely to be greatest in habitats such as arable and horticultural, improved grassland and built up areas where soil metal concentrations are more frequently elevated. - Metal distributions and risks explained by balance of sources and soil property effects on fate.

  10. Anodic stripping voltammetric detection of Zn(II), Cd(II) and Pb(II) of coal gangue at bismuth film glassy carbon electrodes

    Science.gov (United States)

    Wang, Xiu-Teng; Zhang, Yajing; Li, Xiaoyan; Xu, Ling; Lin, Ling; Chen, Qian; Yang, Shuo

    2018-02-01

    For coal gangue it is very important to detect the heavy metals of the products in view of environment risk control, because the heavy metals in coal gangue can cause multiple significant toxic effects. Most of the techniques now available are more suitable for laboratory conditions only and usually cost much testing time. In this work, we develop a new rapid detecting method of Zn(II), Cd(II) and Pb(II) in coal gangue based on anodic stripping voltammetry. Through a large number of experiments, operational parameters have been optimized. This work provides a quick and convenient detection method for heavy metals in coal gangue.

  11. 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)

    Teodorova, S.; Metcheva, R.; Topashka-Ancheva, M.

    2003-01-01

    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

  12. Concentrations of As, Ca, Cd, Co, Cr, Cu, Fe, Hg, K, Mg, Mn, Mo, Na, Ni, Pb, and Zn in uruguayan rice determined by atomic absorption spectrometry

    Directory of Open Access Journals (Sweden)

    Mario E. Rivero Huguet

    2011-04-01

    Full Text Available The United Nations General Assembly declared the year 2004 the International Year of Rice and the concept "Rice is life". The largest nutritional problems occurring globally are protein-energy malnutrition, and Ca, Fe, I, Zn, and vitamin A deficiency. In this report, 49 rice samples (Oryza sativa L. were digested by dry ashing in order to determine As, Cd, Cr, and Pb by ETA-AAS; while Ca, Co, Cu, Fe, K, Mg, Mo, Mn, Na, Ni, and Zn were determined by FAAS; and Hg by CV-AAS using microwave-assisted decomposition. The following concentration ranges were obtained for Ca (9.1-15 mg/100 g, Cd (2.30-4.12 µg/kg, Co (41-60 µg/kg, Cu (1.33-180 mg/kg, Fe (4.41-7.15 mg/kg, K (167-217 mg/100 g, Mg (45-121 mg/100 g, Mo (0.52-0.97 mg/kg, Mn (5.45-25.4 mg/kg, Na (0.95-2.50 mg/100g, Ni (0.53-0.72 mg/kg, and Zn (5.86-12.6 mg/kg. Mean recoveries of elements from fortified rice were: 87±12% for As, 95.3±8.9% for Ca, 106.2±7.7% for Cd, 103.3±6.5% for Co, 89.4±8.1% for Cr, 99.3±4.6% for Cu, 103±10% for Fe, 96.3±9.3% for Hg, 95.4±12% for K, 98.3±8.0% for Mg, 93.4±7.8% for Mo, 95.3±9.9% for Mn, 89±12% for Na, 90.3±9.7% for Ni, 91.2±5.5% for Pb and 92.0±9.4% for Zn. The concentrations of the minerals and microelements studied fall within the typical range of rice grown around the world. Potassium was the most abundant mineral, followed by Mg and Ca; among microelements, the concentrations of Cu, Fe, Mo, Mn, Na, and Zn in rice were outstanding. It was also found that the milling process highly affects the K, Mg, Mn, Na, and Zn concentrations, while it has little influence on Ca, Co, Cu, and Fe. On the other hand, there is a loss of Ca, Fe, and Mn during the parboiling process. Recent studies have shown the potential to exploit the genetic variation of rice seeds with regard to the concentration of some minerals (Ca, Fe, Zn, etc. without affecting yield or adding new traits. All rice samples tested showed lower levels of As, Cd, Hg, and Pb in comparison

  13. Effective removal of heavy metal ions Cd2+, Zn2+, Pb2+, Cu2+ from aqueous solution by polymer-modified magnetic nanoparticles.

    Science.gov (United States)

    Ge, Fei; Li, Meng-Meng; Ye, Hui; Zhao, Bao-Xiang

    2012-04-15

    We prepared novel Fe(3)O(4) magnetic nanoparticles (MNPs) modified with 3-aminopropyltriethoxysilane (APS) and copolymers of acrylic acid (AA) and crotonic acid (CA). The MNPs were characterized by transmission electron microscopy, X-ray diffraction, infra-red spectra and thermogravimetric analysis. We explored the ability of the MNPs for removing heavy metal ions (Cd(2+), Zn(2+), Pb(2+) and Cu(2+)) from aqueous solution. We investigated the adsorption capacity of Fe(3)O(4)@APS@AA-co-CA at different pH in solution and metal ion uptake capacity as a function of contact time and metal ion concentration. Moreover, adsorption isotherms, kinetics and thermodynamics were studied to understand the mechanism of the synthesized MNPs adsorbing metal ions. In addition, we evaluated the effect of background electrolytes on the adsorption. Furthermore, we explored desorption and reuse of MNPs. Fe(3)O(4)@APS@AA-co-CA MNPs are excellent for removal of heavy metal ions such as Cd(2+), Zn(2+), Pb(2+) and Cu(2+) from aqueous solution. Furthermore, the MNPs could efficiently remove the metal ions with high maximum adsorption capacity at pH 5.5 and could be used as a reusable adsorbent with convenient conditions. Copyright © 2011 Elsevier B.V. All rights reserved.

  14. Plant uptake and geochemical phase distribution of Cd, Pb and Zn from soils after application of baghouse dust from the electric arc furnace production of steel

    Energy Technology Data Exchange (ETDEWEB)

    Rule, J.H. [Old Dominion Univ., Norfolk, VA (United States). Dept. of Chemistry and Biochemistry; Adriano, D.C. [Georgia Univ., Savannah River Ecology Laboratory, Aiken (United States)

    1997-12-31

    The objectives of this study are to determine the uptake of Cd, Pb and Zn from two soils (silt loam and sandy loam) by the common dandelion, Taraxacum officinale Weber, and ragweed, Ambrosia artemisiifolia L., after application of varying rates of flue dust, to determine the geochemical phase distribution of Cd, Pb and Zn of treated soils, to examine the effect of pH on the phase distribution and plant uptake and to measure the correlation between plant uptake and metals in the geochemical phases. Carbonate, including metal hydroxides, was the major geochemical phase for the metals in the flue dust and treated soils. Especially for the plants grown on the silt loam, yield decreased dramatically as flue dust treatment rate increased and a significant pH effect was observed. Plant uptake of the metals increased with increasing treatment level but the pattern of uptake varied with the element and plant species. Concentrations of the metals were generally greater in plant roots than leaves or stems. Due to very low biomass at high treatment levels, neither species seems to have potential for stabilization of highly contaminated soils but further studies are warranted on the use of the dandelion as a phyto-monitor. Typically, there was a significant correlation between plant concentrations and levels in all soil geochemical phases for all metals. The results of this study confirm the utility of selective sequential chemical extractants in predicting plant uptake of trace metals from contaminated soils

  15. A two-step leaching method designed based on chemical fraction distribution of the heavy metals for selective leaching of Cd, Zn, Cu, and Pb from metallurgical sludge.

    Science.gov (United States)

    Wang, Fen; Yu, Junxia; Xiong, Wanli; Xu, Yuanlai; Chi, Ru-An

    2018-01-01

    For selective leaching and highly effective recovery of heavy metals from a metallurgical sludge, a two-step leaching method was designed based on the distribution analysis of the chemical fractions of the loaded heavy metal. Hydrochloric acid (HCl) was used as a leaching agent in the first step to leach the relatively labile heavy metals and then ethylenediamine tetraacetic acid (EDTA) was applied to leach the residual metals according to their different fractional distribution. Using the two-step leaching method, 82.89% of Cd, 55.73% of Zn, 10.85% of Cu, and 0.25% of Pb were leached in the first step by 0.7 M HCl at a contact time of 240 min, and the leaching efficiencies for Cd, Zn, Cu, and Pb were elevated up to 99.76, 91.41, 71.85, and 94.06%, by subsequent treatment with 0.2 M EDTA at 480 min, respectively. Furthermore, HCl leaching induced fractional redistribution, which might increase the mobility of the remaining metals and then facilitate the following metal removal by EDTA. The facilitation was further confirmed by the comparison to the one-step leaching method with single HCl or single EDTA, respectively. These results suggested that the designed two-step leaching method by HCl and EDTA could be used for selective leaching and effective recovery of heavy metals from the metallurgical sludge or heavy metal-contaminated solid media.

  16. Distribution of some heavy and essential metals Cd, Pb, Cu, Fe and Zn in Mango fruit (Mangifera Indica L. cultivated in Different Regions of Pakistan

    Directory of Open Access Journals (Sweden)

    NUSRAT jalbani

    2015-12-01

    Full Text Available  In the present study, the concentrations of Cd, Pb, Cu, Zn and Fe from 50 mango samples (Mangifera indica L. were detected by electro-thermal/flame atomic absorption spectrometry (ETAAS/FAAS. In this study three varieties such as Dusahri, Langra and Chaunsa were collected from different regions (Multan, Sadiqabad, Rahimyar Khan and Mirpurkhas of Pakistan.  The effect of different varieties and environmental conditions on metal accumulation was also investigated. The aim of this study is to compare the level of essential and toxic metal in different regions and correlate the differences observed in metal accumulation to environmental conditions. The accuracy of the conventional acid digestion (CAD method was checked by analyzing Certified Reference Materials (CRM i.e. fortified water (TMDA-70, apple leaves (1515 and standard addition technique. The limit of detections (LODs of the method were found to be 0.113, 2.0, 22.7, 3.85 and 3.05 µg L-1 for Pb, Cd, Cu, Fe, and Zn, respectively.

  17. 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+.

  18. 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.

  19. Cd, Pb and Zn oral bioaccessibility of urban soils contaminated in the past by atmospheric emissions from two lead and zinc smelters.

    Science.gov (United States)

    Roussel, H; Waterlot, C; Pelfrêne, A; Pruvot, C; Mazzuca, M; Douay, F

    2010-05-01

    Ingestion of dust or soil particles could pose a potential health risk due to long-term metal trace element (MTE) exposure. Twenty-seven urban topsoil samples (kitchen garden and lawn) were collected and analyzed for Cd, Pb and Zn using the unified Bioaccessibility Research Group of Europe (BARGE) method (UBM) test to estimate the human bioaccessibility of these elements. The quantities of Cd, Pb and Zn extracted from soils indicated, on average, 68, 62 and 47% bioaccessibility, respectively, in the gastric phase and 31, 32 and 23% bioaccessibility, respectively, in the gastro-intestinal phase. Significant positive correlations were observed between concentrations extracted with UBM and total MTE contents. Stepwise multiple regression analysis showed that human bioaccessibility was also affected by some physico-chemical soil parameters (i.e. total nitrogen, carbonates, clay contents and pH). The unified test presents some valuable data for risk assessment. Indeed, the incorporation of oral bioaccessible concentrations into risk estimations could give more realistic information for health risk assessment.

  20. 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.

  1. Utilization of water hyacinth weed (Eichhornia crassipes) for the removal of Pb(II), Cd(II) and Zn(II) from aquatic environments: an adsorption isotherm study.

    Science.gov (United States)

    Mahamadi, C; Nharingo, T

    2010-10-01

    The potential of Eichhornia crassipes biomass for the adsorption of three metal ions, Pb(II), Cd(II) and Zn(II), from aqueous solution was studied using five two-parameter adsorption isotherm equations--Langmuir, Freundlich, Flory-Huggins, Temkin and Redlich-Peterson isotherms. The equilibrium adsorption data were obtained at different initial metal ion concentrations (C0 = 10-60 mg/L), 3 h contact time, 30 degrees C temperature, a dosage of 2 g/L, agitation rate of 150 rpm and buffered at pH 4.84. Langmuir isotherms gave monolayer sorption capacities (qm) of 26.32, 12.60 and 12.55 mg/g for Pb(II), Cd(II) and Zn(II) metal ions, respectively. The same trend of metal uptake was indicated by plots of sorption favourability (S(F)). Negative values of deltaGads0 indicated that the adsorption was spontaneous and exothermic in nature, and values from the Temkin isotherm constant, bT, suggested a mechanism consistent with an ion-exchange process. The results from these studies indicated that E. crassipes biomass has promising potential for the removal of toxic metals from aquatic environments.

  2. Comprehensive risk assessment and source identification of selected heavy metals (Cu, Cd, Pb, Zn, Hg, As) in tidal saltmarsh sediments of Shuangtai Estuary, China.

    Science.gov (United States)

    Liu, Chang-Fa; Li, Bing; Wang, Yi-Ting; Liu, Yuan; Cai, Heng-Jiang; Wei, Hai-Feng; Wu, Jia-Wen; Li, Jin

    2017-10-06

    Heavy metals do not degrade and can remain in the environment for a long time. In this study, we analyzed the effects of Cu, Cd, Pb, Zn, Hg, and As, on environmental quality, pollutant enrichment, ecological hazard, and source identification of elements in sediments using data collected from samples taken from Shuangtai tidal wetland. The comprehensive pollution indices were used to assess environmental quality; fuzzy similarity analysis and geoaccumulation index were used to analyze pollution accumulation; correlation matrix, principal component analysis, and clustering analysis were used to analyze pollution source; environmental risk index and ecological risk index were used to assess ecological risk. The results showed that the environmental quality was either clean or almost clean. Pollutant enrichment analysis showed that the four sub-regions had similar pollution-causing metals to the background values of the soil element of the Liao River Plain, which were ranked according to their similarity. Source identification showed that all the elements were correlated. Ecological hazard analysis showed that the environmental risk index in the study area was less than zero, posing a low ecological risk. Ecological risk of the six elements was as follows: As > Cd > Hg > Cu > Pb > Zn.

  3. Heavy Metal (As, Cd, Cu, Hg, Pb and Zn) Distribution in Topsoil Developed on Alluvial Sediments of the Drava and Sava Rivers in NW Croatia

    OpenAIRE

    Halamić, J.; Galović, L.; Šparica, M.

    2003-01-01

    In the region of north-western Croatia (NWC) 328 topsoil samples were taken (from a depth of 0 to 25 cm). The composite samples were analyzed after near total decomposition (a hot acid mixture: HClO4–HNO3–HCl–HF at 200°C) by ICP–AES for As, Cd, Cu, Pb and Zn. Hg was analysed by cold vapour AAS. The following element concentration ranges were acquired: As 2–74 mg/kg (geometric mean 8 mg/kg), Cd 0.4–9.4 mg/kg (geometric mean 0.4 mg/kg), Cu 5–248 mg/kg (geometric mean 22 mg/kg), Hg 5–4,535 mg/t ...

  4. Characterization of Cd-, Pb-, Zn-resistant endophytic Lasiodiplodia sp. MXSF31 from metal accumulating Portulaca oleracea and its potential in promoting the growth of rape in metal-contaminated soils.

    Science.gov (United States)

    Deng, Zujun; Zhang, Renduo; Shi, Yang; Hu, Li'ao; Tan, Hongming; Cao, Lixiang

    2014-02-01

    The aim of this study was to characterize the features of a Cd-, Pb-, and Zn-resistant endophytic fungus Lasiodiplodia sp. MXSF31 and to investigate the potential of MXSF31 to remove metals from contaminated water and soils. The endophytic fungus was isolated from the stem of Portulaca oleracea growing in metal-contaminated soils. The maximum biosorption capacities of MXSF31 were 3.0 × 10(3), 1.1 × 10(4), and 1.3 × 10(4) mg kg(-1) for Cd, Pb, and Zn, respectively. The biosorption processes of Cd, Pb, and Zn by MXSF31 were well characterized with the pseudo-second-order kinetic model. The biosorption isotherm processes of Pb and Zn by the fungus were fitted better with the Langmuir model, while the biosorption processes of Cd was better fitted with the Freundlich model. The biosorption process of MXSF31 was attributed to the functional groups of hydroxyl, amino, carbonyl, and benzene ring on the cell wall. The active biomass of the strain removed more Cd, Pb, and Zn (4.6 × 10(4), 5.6 × 10(5), and 7.0 × 10(4) mg kg(-1), respectively) than the dead biomass. The inoculation of MXSF31 increased the biomass of rape (Brassica napus L.), the translocation factor of Cd, and the extraction amount of Cd by rape in the Cd+Pb-contaminated soils. The results indicated that the endophytic fungus strain had the potential to remove heavy metals from water and soils contaminated by multiple heavy metals, and plants accumulating multiple metals might harbor diverse fungi suitable for bioremediation of contaminated media.

  5. Corrosion Behavior of Alloy 625 in PbSO4-Pb3O4-PbCl2-ZnO-10 Wt Pct CdO Molten Salt Medium

    Science.gov (United States)

    Mohammadi Zahrani, E.; Alfantazi, A. M.

    2012-08-01

    Corrosion behavior and degradation mechanisms of alloy 625 under a 47.288 PbSO4-12.776 Pb3O4-6.844PbCl2-23.108ZnO-10CdO (wt pct) molten salt mixture under air atmosphere were studied at 873 K, 973 K, and 1073 K (600 °C, 700 °C, and 800 °C). Electrochemical impedance spectroscopy (EIS), open circuit potential (OCP) measurements, and potentiodynamic polarization techniques were used to evaluate the degradation mechanisms and characterize the corrosion behavior of the alloy. Morphology, chemical composition, and phase structure of the corrosion products and surface layers of the corroded specimens were studied by scanning electron microscopy/energy-dispersive X-ray (SEM/EDX) and X-ray map analyses. Results confirmed that during the exposure of alloy 625 to the molten salt, chromium was mainly dissolved through an active oxidation process as CrO3, Cr2O3, and CrNbO4, while nickel dissolved only as NiO in the system. Formation of a porous and nonprotective oxide layer with low resistance is responsible for the weak protective properties of the barrier layer at high temperatures of 973 K and 1073 K (700 °C and 800 °C). There were two kinds of attack for INCONEL 625, including general surface corrosion and pitting. Pitting corrosion occurred due to the breakdown of the initial oxide layer by molten salt dissolution of the oxide or oxide cracking.

  6. Different binding modes of Cu and Pb vs. Cd, Ni, and Zn with the trihydroxamate siderophore desferrioxamine B at seawater ionic strength

    Energy Technology Data Exchange (ETDEWEB)

    Schijf, Johan; Christenson, Emily A.; Potter, Kailee J.

    2015-07-01

    The solution speciation in seawater of divalent trace metals (Cd, Cu, Ni, Pb, Zn) is dominated by strong, ostensibly metal-specific organic ligands that may play important roles in microbial metal acquisition and/or detoxification processes. We compare the effective stabilities of these metal-organic complexes to the stabilities of their complexes with a model siderophore, desferrioxamine B (DFOB). While metal-DFOB complexation has been studied in various dilute but often moderately coordinating media, for the purpose of this investigation we measured the stability constants in a non-coordinating background electrolyte at seawater ionic strength (0.7 M NaClO4). Potentiometric titrations of single metals (M) were performed in the presence of ligand (L) at different M:L molar ratios, whereupon the stability constants of multiple complexes were simultaneously determined by non-linear regression of the titration curves with FITEQL, using the optimal binding mode for each metal. Cadmium, Ni, and Zn, like trivalent Fe, sequentially form a bi-, tetra-, and hexadentate complex with DFOB as pH increases, consistent with their coordination number of 6 and regular octahedral geometry. Copper has a Jahn-Teller-distorted square-bipyramidal geometry whereas the geometry of Pb is cryptic, involving a range of bond lengths. Supported by a thermodynamic argument, our data suggest that this impedes binding of the third hydroxamate group and that the hexadentate Cu-DFOB and Pb-DFOB complex identified in earlier reports may instead be a deprotonated tetradentate complex. Absence of the hexadentate complex promotes the formation of a dinuclear (bidentate-tetradentate) complex, M2HL2+, albeit not for Pb in 0.7 M NaCl, evidently due to extensive complexation with chloride. Stabilities of the hexadentate Ni-DFOB, Zn-DFOB, and the tetradentate Pb-DFOB complex are nearly equal, yet about 2 orders of magnitude higher and 4 orders of magnitude lower than those of the hexadentate Cd-DFOB and

  7. 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)

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

    2012-01-01

    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. - 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.

  8. Effect of bamboo and rice straw biochars on the mobility and redistribution of heavy metals (Cd, Cu, Pb and Zn) in contaminated soil.

    Science.gov (United States)

    Lu, Kouping; Yang, Xing; Gielen, Gerty; Bolan, Nanthi; Ok, Yong Sik; Niazi, Nabeel Khan; Xu, Song; Yuan, Guodong; Chen, Xin; Zhang, Xiaokai; Liu, Dan; Song, Zhaoliang; Liu, Xingyuan; Wang, Hailong

    2017-01-15

    Biochar has emerged as an efficient tool to affect bioavailability of heavy metals in contaminated soils. Although partially understood, a carefully designed incubation experiment was performed to examine the effect of biochar on mobility and redistribution of Cd, Cu, Pb and Zn in a sandy loam soil collected from the surroundings of a copper smelter. Bamboo and rice straw biochars with different mesh sizes (Heavy metal concentrations in pore water were determined after extraction with 0.01 M CaCl 2 . Phytoavailable metals were extracted using DTPA/TEA (pH 7.3). The European Union Bureau of Reference (EUBCR) sequential extraction procedure was adopted to determine metal partitioning and redistribution of heavy metals. Results showed that CaCl 2 -and DTPA-extractable Cd, Cu, Pb and Zn concentrations were significantly (p soils, especially at 5% application rate, than those in the unamended soil. Soil pH values were significantly correlated with CaCl 2 -extractable metal concentrations (p metal fractions, and the effect was more pronounced with increasing biochar application rate. The effect of biochar particle size on extractable metal concentrations was not consistent. The 5% rice straw biochar treatment reduced the DTPA-extractable metal concentrations in the order of Cd metals were mainly bound in the soil organic matter fraction. The results demonstrated that the rice straw biochar can effectively immobilize heavy metals, thereby reducing their mobility and bioavailability in contaminated soils. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. Automated preconcentration of Fe, Zn, Cu, Ni, Cd, Pb, Co, and Mn in seawater with analysis using high-resolution sector field inductively-coupled plasma mass spectrometry.

    Science.gov (United States)

    Rapp, Insa; Schlosser, Christian; Rusiecka, Dagmara; Gledhill, Martha; Achterberg, Eric P

    2017-07-11

    A rapid, automated, high-throughput analytical method capable of simultaneous analysis of multiple elements at trace and ultratrace levels is required to investigate the biogeochemical cycle of trace metals in the ocean. Here we present an analytical approach which uses a commercially available automated preconcentration device (SeaFAST) with accurate volume loading and in-line pH buffering of the sample prior to loading onto a chelating resin (WAKO) and subsequent simultaneous analysis of iron (Fe), zinc (Zn), copper (Cu), nickel (Ni), cadmium (Cd), lead (Pb), cobalt (Co) and manganese (Mn) by high-resolution inductively-coupled plasma mass spectrometry (HR-ICP-MS). Quantification of sample concentration was undertaken using isotope dilution for Fe, Zn, Cu, Ni, Cd and Pb, and standard addition for Co and Mn. The chelating resin is shown to have a high affinity for all analyzed elements, with recoveries between 83 and 100% for all elements, except Mn (60%) and Ni (48%), and showed higher recoveries for Ni, Cd, Pb, Co and Mn in direct comparison to an alternative resin (NOBIAS Chelate-PA1). The reduced recoveries for Ni and Mn using the WAKO resin did not affect the quantification accuracy. A relatively constant retention efficiency on the resin over a broad pH range (pH 5-8) was observed for the trace metals, except for Mn. Mn quantification using standard addition required accurate sample pH adjustment with optimal recoveries at pH 7.5 ± 0.3. UV digestion was necessary to increase recovery of Co and Cu in seawater by 15.6% and 11.4%, respectively, and achieved full break-down of spiked Co-containing vitamin B 12 complexes. Low blank levels and detection limits could be achieved (e.g., 0.029 nmol L -1 for Fe and 0.028 nmol L -1 for Zn) with the use of high purity reagents. Precision and accuracy were assessed using SAFe S, D1, and D2 reference seawaters, and results were in good agreement with available consensus values. The presented method is ideal for

  10. 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.

  11. 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)

    Argota Perez, George; Argota Coello, Humberto; Rodriguez Amado, Jesus; Fernandez Heredia, Angel

    2013-01-01

    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

  12. 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

    95% model prediction bounds. A positive correlation between the dry deposition and the dry (wind) removal rates was revealed as well as a negative correlation between the wet removal (wash-off) rate and the ratio between the dry deposition and wind removal rates, which determines the maximum pool......A dynamic conceptual and lumped accumulation wash-off model (SEWSYS) is uncertainty-calibrated with Zn, Cu, Pb and Cd field data from an intensive, detailed monitoring campaign. We use the generalized linear uncertainty estimation (GLUE) technique in combination with the Metropolis algorithm, which...... allows identifying a range of behavioral model parameter sets. The small catchment size and nearness of the rain gauge justified excluding the hydrological model parameters from the uncertainty assessment. Uniform, closed prior distributions were heuristically specified for the dry and wet removal...

  13. 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)

    Avila P, P.

    1995-01-01

    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)

  14. Diffusion coefficients for Tl, Pb, Cd, In, Zn, Bi, As, Mo and Sb in hydrous rhyolite at 100-200 MPa

    Science.gov (United States)

    Berlo, Kim; Brooker, Richard; Wilke, Max

    2014-05-01

    A series of experiments have been conducted to determine the diffusivities of Tl, Pb, Cd, In, Zn, Bi, As, Mo and Sb in hydrous rhyolitic melt. Diffusion experiments used two adjoining glass cylinder of the same hydrous composition, one doped with the elements of interest at ~ 100 ppm. These couples were rapidly heated to 850, 1000 and 1150°C at 100-200 MPa for a few hours. After quenching the sectioned charges were analyzed by both synchrotron XRF (The Diamond Light Source) and LA-ICP-MS (University of Oxford). The data shows excellent correlation between these two techniques. The diffusion profiles were fitted to a 1-D diffusion couple equation to determine the diffusivities and fitting to the different temperature runs defined the Arrhenius parameters. We find that for 850°C the diffusion coefficients follow the trend Tl>Pb>Cd>Zn>In>Bi>As>Sb>Mo. Additional experiments were performed with either S or Cl added (to both sides of the diffusion couple). In general S increases the diffusion rate of all metals except Mo and Sb, which diffuse slower in the presence of S. Chlorine also speeds up the diffusion of metals with the exception of In, Mo and Sb. The systematic change in diffusivities of these metals and their different behaviour in the presence of the ligands that are also observed to be significant in volcanic gases, are important in determining the distribution of these metals during degassing (e.g. MacKenzie and Canil, 2008). This is particularly important in a dynamic environment such as a volcanic conduit. There are also implications for economic exploration and well as hazard mitigation.

  15. Origen y comportamiento de Cd, Cr, Cu, Pb y Zn en el subsistema acuífero de la Plana de Castellón

    Directory of Open Access Journals (Sweden)

    Morell, I.

    1996-12-01

    Full Text Available A study on Cd, Cr, Cu, Pb and Zn concentrations in Castellón Plain aquifer has been carried out in order to know if the industrial activity of this zone affects to the groundwater quality. Adsorption processes and relative migration velocity of these metals through the soils of this zone have also been studied. Metal concentrations in the aquifer are lower than those expected in an area with an intense industrial activity. It can be due to the fact that these metals show high adsorption coefficients in the soils and very low migration velocities through them, so it is no probable that the metals from the waste-waters reach the aquifer, or they take some time to reach it.En el presente trabajo se estudia la concentración de Cd, Cr, Cu, Pb y Zn en el acuífero de la Plana de Castellón, para conocer si la actividad industrial de la zona afecta a la calidad de las aguas subterráneas. Asimismo se estudian los procesos de adsorción y velocidad de migración de dichos metales en suelos de la zona. Las concentraciones de metales en el acuífero son más bajas de lo que cabría esperar, dada la intensa actividad industrial de la zona. Ello puede ser debido a que, dado que los metales presentan altos coeficientes de adsorción en los suelos y una velocidad de migración a través de los mismos muy reducida, no parece probable que dichos elementos procedentes de vertidos de aguas residuales lleguen a alcanzar el acuífero, o, en todo caso, tardarán muchos años en hacerlo, ya que el suelo actúa reteniéndolos y retrasando su llegada al mismo.

  16. Influence of the heavy metals Pb, Cd, Zn, Mn, Cu, Hg and Be on the glutathione-S-transferases of rat liver. Einfluss der Schwermetalle Pb, Cd, Zn, Mn, Cu, Hg und Be auf die Glutathion-S-Transferasen der Rattenleber

    Energy Technology Data Exchange (ETDEWEB)

    Hosny Abd El-Fadil, I.H.

    1988-07-04

    The aim of this study was to explore the influence of the heavy metal salts Pb-acetate, CdCl[sub 2], ZnSO[sub 4], MnCl[sub 2], CuCl, HgNO[sub 3], and BeSO[sub 4] on the two glutathione S-transferase (GST) isoenzymes glutathione S-epoxide transferase and glutathione S-aryltransferase after addition of these salts to rat liver enzyme preparations. Rat liver enzyme preparations were also investigated after pretreatment of the animals with these salts. (orig./VT).

  17. 210Po Activity and concentrations of selected trace elements (As, Cd, Cu, Hg, Pb, Zn) in the muscle tissue of tunas Thunnus albacares and Katsuwonus pelamis from the Eastern Pacific Ocean.

    Science.gov (United States)

    Ruelas-Inzunza, Jorge; Soto-Jiménez, Martín Federico; Ruiz-Fernández, Ana Carolina; Bojórquez-Leyva, Humberto; Pérez-Bernal, Hascibe; Páez-Osuna, Federico

    2012-12-01

    Daily mineral intake (DMI) of Cu and Zn, percentage weekly intake (PWI) of As, Cd, Hg, Pb, and doses of (210)Po were estimated by using their elemental concentration in muscle of two tuna species and the average tuna consumption in Mexico. Skipjack tuna Katsuwonus pelamis had significantly (p tuna Thunnus albacares, whereas Pb concentrations (0.18 μg g(-1) dw) were significantly (p Cu > As > Hg > Pb > Cd. In T. albacares, concentrations of Cd and Pb in muscle tissue were positively correlated (p < 0.05) with weight of specimens, while Cu was negatively correlated. DMI values were below 10 %. PWI figures (<2 %) are not potentially harmful to human health. (210)Po concentration in T. albacares and K. pelamis accounts for 13.5 to 89.7 % of the median individual annual dose (7.1 μSv) from consumption of marine fish and shellfish for the world population.

  18. Bioaccumulation of metals (Cd, Cu, Ni, Pb and Zn) in suspended cultures of blue mussels exposed to different environmental conditions

    Science.gov (United States)

    Maar, Marie; Larsen, Martin Mørk; Tørring, Ditte; Petersen, Jens Kjerulf

    2018-02-01

    Farming of suspended mussels is important for generating high protein food and animal feed or for removing nutrients in eutrophic systems. However, the harvested mussels must not be severely contaminated by pollutants posing a potential health risk for the consumers. The present study estimated the bioaccumulation of cadmium, copper, nickel, lead and zinc in suspended blue mussels (Mytilus edulis L.) in the Limfjorden, Denmark, based on observations and modelling. Modelling was used to assess the suitability of suspended blue mussels as animal feed and food products at sea water metal concentrations corresponding to Good Ecological Status (GES) in the European Union Water Framework Directive (WFD) and in future climate change scenarios (higher metal concentrations and higher temperatures). For this purpose, GES is interpreted as good chemical status for the metals using the Environmental Quality Standards (EQS) defined in the WFD priority substance daughter directives. Observations showed that suspended mussels were healthy with respect to metal pollution and generally less polluted than benthic mussels due to the smaller contact with the contaminated sediment. The model results showed that the WFD targets for Cd, Ni and Pb are not protective with respect to marine mussel production and probably should be reduced for marine waters. Climate changes may increase the metal contamination of mussels, but not to any critical level at the relatively unpolluted study sites. In conclusion, WFD targets should be revised to assure that the corresponding body burdens of metals in mussels are below the safety limits according to the EU Directives and the Norwegian classification for animal feed and food production.

  19. 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)

    Sartaj, M.; Fatollahi, F.; Filizadeh, Y.

    2005-01-01

    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

  20. Short-term changes in Ca, Pb, Zn and Cd concentrations of the garden snail Helix aspersa Muller from a central London car park

    Energy Technology Data Exchange (ETDEWEB)

    Beeby, A.; Eaves, S.L.

    1983-03-01

    Helix aspersa were collected from a car park with a high degree of Pb and Zn pollution over a period of 102 days following the end of aestivation. Analysis of whole soft tissues demonstrates a high variability in both Pb and Ca levels in the short term, possibly associated with shell formation. Pb, Zn and Ca concentrations are also shown to vary with age-class. No simple relationship between total Ca and total heavy metal levels was found, and it is concluded that Ca does not account for the high variability between individuals. The rate of loss of each metal is shown to vary with age-class.

  1. Contamination of Pb Cd Cu Zn in black pomfret Formio niger and tongue sand Cynoglossus lingua fish caught from the western part of Madura strait and its safe limits consumption

    Directory of Open Access Journals (Sweden)

    Acivrida Mega Charisma

    2014-03-01

    Full Text Available Contamination of Pb, Cd, Cu, Zn in the flesh on the two types of fish consisting pelagic fish include Black pomfert (Formio niger whereas among other demersal fish include Tongue sand (Cynoglossus lingua, was conducted in March-December 2013, which was taken from the western part of Madura Strait (Gresik-Ujung pangkah, Surabaya-Kenjeran, and Sidoarjo-Sedati. Pb, Cd, Cu, and Zn detected using AAS (Atomic Absorption Spectrometry brand Shimadzu AA-6200. The highest content of heavy metals, namely Pb in Cynoglossus lingua from the Sedati (5.63ppm ±0.05, while a low of Cd in Formio niger from the Ujung pangkah (0.20ppm ±0.004. The results show that there is a correlation between heavy metal with fish but not significantly. The content of Pb, Cd, Cu, Zn in 2 fish species originating from all locations stated below the exposure limits for consumption. Safe limit fish consumption of Formio niger is based on the WHO PTWI of 347.43 grams / week and Cynoglossus lingua 191.25 grams / week.

  2. 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

    International Nuclear Information System (INIS)

    Salazar, María Julieta; Rodriguez, Judith Hebelen; Nieto, Gastón Leonardo; Pignata, María Luisa

    2012-01-01

    Highlights: ► Soybean grown near metal sources presents a toxicological hazard from heavy metals for Chinese consumers. ► Rhizosphere soil is the most suitable compartment for toxicological studies. ► 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.

  3. 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].

    Science.gov (United States)

    Salazar, María Julieta; Rodriguez, Judith Hebelen; Leonardo Nieto, Gastón; Pignata, María Luisa

    2012-09-30

    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. Copyright © 2012 Elsevier B.V. All rights reserved.

  4. Study of Fe, Zn, Cu, Cd, Pb concentrations in liver, kidney and muscle tissue of cow and sheep marketed in Hamedan in 2011

    Directory of Open Access Journals (Sweden)

    S Sobhanardakani

    2012-11-01

    Full Text Available Importance of heavy metals in food safety and detrimental effects of their high concentrations in food stuff is well documented. In this study, concentrations of Fe, Zn, Cu, Cd and Pb in kidney, liver and muscle tissues of cow and sheep at Hamedan retails were evaluated. A total number of 180 samples was assessed for the amount of heavy metals as ppb in wet weight. For this, wet-digestion method was used to determine the concentration of given elements by ICP (Varian ES-710. Results showed that the highest concentration of heavy metals was determined in the liver and kidney samples, while the lowest concentration was found in muscle tissue. Among the heavy metals, Fe in cow’s liver had the highest concentration (25507±879 ppb and Cd in muscle tissue of sheep has the lowest concentration (192±54 ppb. In overall, accumulation of heavy metals in tissues of cows was higher than sheep. Statistical comparison of accumulated metals concentration in various tissues of these two animal groups showed significant difference (P

  5. Accumulation of Cr, Cd, Pb, Cu, and Zn by plants in tanning sludge storage sites: opportunities for contamination bioindication and phytoremediation.

    Science.gov (United States)

    Yuan, Yongqiang; Yu, Shen; Bañuelos, G S; He, Yunfeng

    2016-11-01

    Tanning sludge enriched with high concentrations of Cr and other metals has adverse effects on the environment. Plants growing in the metalliferous soils may have the ability to cope with high metal concentrations. This study focuses on potentials of using native plants for bioindication and/or phytoremediation of Cr-contaminated sites. In the study, we characterized plants and soils from six tanning sludge storage sites. Soil in these sites exhibited toxic levels of Cr (averaged 16,492 mg kg -1 ) and other metals (e.g., 48.3 mg Cu kg -1 , 2370 mg Zn kg -1 , 44.9 mg Pb kg -1 , and 0.59 mg Cd kg -1 ). Different metal tolerance and accumulation patterns were observed among the sampled plant species. Phragmites australis, Zephyranthes candida, Cynodon dactylon, and Alternanthera philoxeroides accumulated moderate-high concentrations of Cr and other metals, which could make them good bioindicators of heavy metal pollution. High Cr and other metal concentrations (e.g., Cd and Pb) were found in Chenopodium rubrum (372 mg Cr kg -1 ), Aster subulatus (310 mg Cr kg -1 ), and Brassica chinensis (300 mg Cr kg -1 ), being considered as metal accumulators. In addition, Nerium indicum and Z. candida were able to tolerate high concentrations of Cr and other metals, and they may be used as preferable pioneer species to grow or use for restoration in Cr-contaminated sites. This study can be useful for establishing guidelines to select the most suitable plant species to revegetate and remediate metals in tanning sludge-contaminated fields.

  6. Contamination and Health Risks from Heavy Metals (Cd and Pb and Trace Elements (Cu and Zn in Dairy Products

    Directory of Open Access Journals (Sweden)

    Hamid Reza Ghafari

    2017-08-01

    Conclusion: Considering the serious contamination of some brands of butter and cheese by Cu and Pb, a control of heavy metals and trace elements levels during the whole production processing of dairy products must be applied.

  7. Forest Soil Pollution with Heavy Metals (Pb, Zn, Cd, and Cu in the Area of the “French Mines” on the Medvednica Mountain, Republic of Croatia

    Directory of Open Access Journals (Sweden)

    Ivan Perković

    2017-01-01

    Full Text Available Background and Purpose: This paper deals with the results of the investigation of the selected heavy metal contents in forest soil in the region of an abandoned mine. The analysis of the forest ecosystem soil on the Medvednica Mountain was conducted in the region of the so-called “French Mines” (FM. The elements selected for analyses were cadmium (Cd, copper (Cu, lead (Pb, and zinc (Zn because of their toxicological characteristics. Material and Methods: In the investigated area - five entrances of the FM - composite topsoil samples (0–5 cm were taken. Those samples were compared to the control samples which were taken outside the area affected by mines. The soil samples were analysed for the following parameters: pH, particle size distribution, organic C content and pseudo-total mass fractions of the selected heavy metals. The heavy metals were determined by atomic emission spectrometry with inductively coupled plasma (ICP-MS. Results and Conclusion: The results reveal that the soil is locally polluted, i.e. the highest mass fraction values of these four heavy metals were found in the area of the FM. Average pseudo-total fraction of Cd in the analysed topsoil samples was in the range of 0.17–4.41 mg·kg−1 (median: 0.97 mg·kg−1. Cu was found in the range of 4.54–1260 mg·kg−1 (median: 45.7 mg·kg−1. In the case of Zn, mass fraction values were found in the range of 36.8–865 mg·kg−1 (median: 137 mg·kg−1. Finally, average values of the pseudo-total fraction of Pb were found in the range of 58.4–12000 mg·kg−1 (median: 238 mg·kg−1. The results reveal that mining activities leave consequences on soil for a long time.

  8. 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.

    Science.gov (United States)

    Kilbride, C; Poole, J; Hutchings, T R

    2006-09-01

    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.

  9. The Adsorption of Pb, Zn, Cu, Ni, and Cd by Modified Ligand in a Single Component Aqueous Solution: Equilibrium, Kinetic, Thermodynamic, and Desorption Studies

    Science.gov (United States)

    Osifo, P.; Ofomaja, A.

    2017-01-01

    In this investigation, an amino functionalized adsorbent was developed by grafting 4-aminobenzoic acid onto the backbone of cross-linked chitosan beads. The 3 sets of beads including chitosan (CX), glutaraldehyde cross-linked chitosan (CCX), and 4-aminobenzoic acid grafted cross-linked chitosan (FGCX) were characterized by FTIR, XRD, SEM, and TGA. The water content and amine concentration of FGCX were determined. The effect of adsorption parameters was studied and the optimum was used for further studies. Equilibrium data was obtained from the adsorption experiment carried out at different initial concentration; the data were applied in isotherm, thermodynamics, and kinetic studies. The Langmuir and Dubinin-Kaganer-Radushkevich (DKR) models were successful in describing the isotherm data for the considered metal ions while the Freundlich and Temkin model fit some of the considered metal ions. Pseudo-second-order and intraparticle model described the kinetic data quite well. Thermodynamic parameters such as Gibb's free energy change (ΔGo), enthalpy change (ΔHo), and entropy change (ΔSo) were calculated and the results showed that the adsorption of Pb, Cu, Ni, Zn, and Cd ions onto FGCX is spontaneous and endothermic in nature. Regeneration of the spent adsorbent was efficient for the considered metal ions. PMID:28607557

  10. 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)

    Kazemzadeh Khoyi, J.; Noori, A. S.; Pourang, N.; Alizadeh, M.; Ghoreishi, H.; Padash, A.

    2013-01-01

    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.

  11. The evaluation of growth and phytoextraction potential of Miscanthus x giganteus and Sida hermaphrodita on soil contaminated simultaneously with Cd, Cu, Ni, Pb, and Zn.

    Science.gov (United States)

    Kocoń, Anna; Jurga, Beata

    2017-02-01

    One of the cheapest, environmentally friendly methods for cleaning an environment polluted by heavy metals is phytoextraction. It builds on the uptake of pollutants from the soil by the plants, which are able to grow under conditions of high concentrations of toxic metals. The aim of this work was to assess the possibility of growing and phytoextraction potential of Miscanthus x giganteus and Sida hermaphrodita cultivated on two different soils contaminated with five heavy metals simultaneously: Cd, Cu, Ni, Pb, and Zn. A 3-year microplot experiment with two perennial energy crops, M. x giganteus and S. hermaphrodita, was conducted in the experimental station of IUNG-PIB in Poland (5° 25' N, 21° 58 'E), in the years of 2008-2010. Miscanthus was found more tolerant to concomitant soil contamination with heavy metals and produced almost double biomass than Sida in all three tested years, independent of soil type. Miscanthus collected greater amount of heavy metals (except for cadmium) in the biomass than Sida. Both energy crops absorb high levels of zinc, lower levels of lead, copper, and nickel, and absorbed cadmium at least, generally more metals were taken from the sandy soil, where plants also yielded better. Photosynthesis net rate of Miscanthus was on average 40% higher compared to Sida. Obtained results indicate that M. x giganteus and S. hermaphrodita can successfully be grown on moderately contaminated soil with heavy metals.

  12. Hassle free synthesis of nanodimensional Ni, Cu and Zn sulfides for spectral sensing of Hg, Cd and Pb: A comparative study.

    Science.gov (United States)

    Ansari, Zarina; Singha, Shib Shankar; Saha, Abhijit; Sen, Kamalika

    2017-04-05

    A simple room temperature synthesis method of Ni, Cu and Zn sulfide nanoparticles (NPs) in aqueous medium is reported here. The NPs stabilized in aqueous medium by the citrate ions were characterized by UV-vis, ζ potentials, TEM and Raman spectroscopic techniques. The solid NPs could be isolated from the aqueous medium when allowed to stand for a prolonged time (~20h). The solids were also characterized by IR and powder X-ray analysis. The nanoparticles were further used for the development of facile optical sensing and detection of heavy metal ions at trace scale. Alterations in the absorption spectra of the generated NPs were indicative of their interactions with heavy metal ions. Raman spectral measurements further validate the detection technique. It is found that out of the three synthesized nanoparticles, nickel sulfide NP is a specific sensor for mercury ions whereas zinc sulfide and copper sulfide NPs act as sensors for Hg 2+ , Cd 2+ and Pb 2+ . Copyright © 2017 Elsevier B.V. All rights reserved.

  13. 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)

    Lopareva-Pohu, Alena; Verdin, Anthony; Garcon, Guillaume; Lounes-Hadj Sahraoui, Anissa; Pourrut, Bertrand; Debiane, Djouher; Waterlot, Christophe; Laruelle, Frederic

    2011-01-01

    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.

  14. Study on the application of electrothermal atomization atomic absorption spectrometry for the determination of metallic Cu, Pb, Zn, Cd traces in sea water samples

    International Nuclear Information System (INIS)

    Nguyen Thi Kim Dung; Doan Thanh Son; Tran Thi Ngoc Diep

    2004-01-01

    The trace amount of some heavy metallic elements (Cu, Zn, Pb, Cd) in sea water samples were determined directly (without separation) and quantitatively by using Electro-Thermal Atomization Atomic Absorption Spectrometry (ETA-AAS). The effect of mainly major constituents such as Na, Mg, Ca, K, and the mutual effect of the trace elements, which were present in the matrix on the absorption intensity of each analyzed element was studied. The adding of a certain chemical modification for each trace element was also investigated in order to eliminate the overall effect of the background during the pyrolysis and atomization. The sea water sample after fitrating through a membrane with 0.45 μm-hole size was injected in to the graphite tube via an autosampler (MPE50). The absorption intensity of each element was then measured on the VARIO-6 under the optimum parameters for spectrometer such as: maximum wavelength, current of hollow cathode lamp, and that for graphite furnace such as dry temperature, pyrolysis temperature, atomization temperature, ect. The analytical procedures were set-up and applied for the determination of these above mentioned elements in the synthesized sea water sample and in the real sea water samples with high precision and accuracy. (author)

  15. Measurements of Cd, Cu, Pb and Zn in the lower reaches of major Eurasian arctic rivers using trace metal clean techniques

    Energy Technology Data Exchange (ETDEWEB)

    Guay, Christopher K.H., E-mail: cguay@pmstllc.co [Pacific Marine Sciences and Technology, 3503 Lakeshore Avenue, Suite 5, Oakland, CA 94610 (United States); Zhulidov, Alexander V. [South Russian Regional Centre for Preparation and Implementation of International Projects (CPPI-S), 200/1 Stachki Av., No. 301, Rostov-on-Don 344090 (Russian Federation); Robarts, Richard D. [UNEP GEMS/Water Programme, c/o National Water Research Institute, National Hydrology Research Centre, 11 Innovation Blvd., Saskatoon, Saskatchewan S7N 3H5 (Canada); Zhulidov, Daniel A.; Gurtovaya, Tatiana Yu. [South Russian Regional Centre for Preparation and Implementation of International Projects (CPPI-S), 200/1 Stachki Av., No. 301, Rostov-on-Don 344090 (Russian Federation); Holmes, Robert M. [The Ecosystems Center, Marine Biological Laboratory, 7 MBL Street, Woods Hole, MA 02543 (United States); Headley, John V. [Aquatic Ecosystem Protection Research Branch, National Water Research Institute, National Hydrology Research Centre, 11 Innovation Blvd., Saskatoon, Saskatchewan S7N 3H5 (Canada)

    2010-02-15

    Concentrations of dissolved and particulate Cd, Cu, Pb and Zn were determined in samples collected in summer 1998 from the lower reaches of six major Eurasian arctic rivers: the Onega, Severnaya Dvina, Mezen, Pechora, Ob and Yenisey. These data comprise some of the earliest measurements of trace metals in Eurasian arctic rivers above the estuaries using recognized clean techniques. Significant (alpha = 0.05) differences were observed among mean concentrations of particulate metals in the individual rivers (F <= 0.006), with highest levels overall observed in the Severnaya Dvina and Yenisey. No significant differences were observed among mean concentrations of dissolved metals in the individual rivers (F = 0.10-0.84). Contributions from anthropogenic sources are suggested by comparison of trace metal ratios in the samples to crustal abundances. These results establish a baseline for assessing future responses of Eurasian arctic river systems to climate-related environmental changes and shifting patterns of pollutant discharge. - We report some of the earliest reliable trace metal data for major Eurasian arctic rivers.

  16. The Adsorption of Pb, Zn, Cu, Ni, and Cd by Modified Ligand in a Single Component Aqueous Solution: Equilibrium, Kinetic, Thermodynamic, and Desorption Studies

    Directory of Open Access Journals (Sweden)

    E. Igberase

    2017-01-01

    Full Text Available In this investigation, an amino functionalized adsorbent was developed by grafting 4-aminobenzoic acid onto the backbone of cross-linked chitosan beads. The 3 sets of beads including chitosan (CX, glutaraldehyde cross-linked chitosan (CCX, and 4-aminobenzoic acid grafted cross-linked chitosan (FGCX were characterized by FTIR, XRD, SEM, and TGA. The water content and amine concentration of FGCX were determined. The effect of adsorption parameters was studied and the optimum was used for further studies. Equilibrium data was obtained from the adsorption experiment carried out at different initial concentration; the data were applied in isotherm, thermodynamics, and kinetic studies. The Langmuir and Dubinin-Kaganer-Radushkevich (DKR models were successful in describing the isotherm data for the considered metal ions while the Freundlich and Temkin model fit some of the considered metal ions. Pseudo-second-order and intraparticle model described the kinetic data quite well. Thermodynamic parameters such as Gibb’s free energy change (ΔGo, enthalpy change (ΔHo, and entropy change (ΔSo were calculated and the results showed that the adsorption of Pb, Cu, Ni, Zn, and Cd ions onto FGCX is spontaneous and endothermic in nature. Regeneration of the spent adsorbent was efficient for the considered metal ions.

  17. Evaluation of assisting agents for electrodialytic removal of Cd, Pb, Zn, Cu and Cr from MSWI fly ash

    DEFF Research Database (Denmark)

    Pedersen, Anne Juul

    2002-01-01

    Different assisting agents (0.25 M ammonium citrate/1.25 % NH3, 0.25 M Na-citrate, 2.5 % NH3, DI water) have been used as assisting agents for the removal of heavy met-als during electrodialytic treatment of municipal solid waste incineration (MSWI) fly ash. In this study, the effectiveness......, probably due to formation of stable tetraammine complexes; whereas the best Pb removal was obtained with 0.25 M Na-citrate (Pb forms very stable chelates with citrate). The best compro-mise for removal of all five metals was obtained with the 0.25 M ammonium citrate/1.25 % NH3 solution....

  18. 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)

    Beltran, P.A.E.; Morales, E.A.

    1987-10-01

    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)

  19. 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.

  20. Equilibrium and Kinetic Studies of Cu (II), Cd (II), Pb (II) and Fe (II ...

    African Journals Online (AJOL)

    ADOWIE PERE

    Adsorption isotherm studies of Cd (II), Pb (II) and Zn (II) ions bioremediation from aqueous solution using unmodified and EDTA-modified maize cob. Eclectica Quimica. 32(1): 33-42. Igwe, JC; Abia, AA (2003). Maize cob and husk as adsorbents or removal of Cd, Pb, and Zn ions from waste water. The physical Sci. 2: 83-94.

  1. Bioavailability of Pb, Zn, Cu, Cd, Ni and Cr in the sediments of the Tessa River: A mining area in the North-West Tunisia

    Science.gov (United States)

    Sebei, Abdelaziz; Helali, Mohamed Amine; Oueslati, Walid; Abdelmalek-Babbou, Chiraz; Chaabani, Fredj

    2018-01-01

    Tessa River is seen as one of the important rivers in Tunisia. Its catchment is known for its agricultural and mining activities, especially the Bougrine and Fedj Lahdhoum mines. Eighteen (18) surface sediments and five (5) water samples were collected from the Tessa River, near these two mining sites. Sediments are essentially sandy (>80%), the most important mineral is quartz (20-73%), then calcite (41%) and dolomites (4%). Heavy metal contents are relatively high near the mining sites, 356 μg g-1 for Pb, 3000 μg g-1 for Zn, and 5 μg g-1 for Cd. These values are lower downstream due to watercourse dilution effects. Other heavy metals: Cu, Ni and Cr, are low, and values are relatively constant in all the studied samples, even near the mining sites. The metals originate from natural sources and not from mining activities. This trend is confirmed by the enrichment factor (EF) where EFNi, EFCu and EFCr are lower or equal to 1, unlike EFPb, EFZn or EFCd where values are much higher (>20). Chemical speciation of these metals does not show any spatial variation. Except for cadmium which is bound to the residual fraction and in the carbonates; all other heavy metals are bound to the five sediment chemical fractions: the residual fraction (>52%), followed by the oxyhydroxides fraction (21%) and carbonates (16%), and finally bound to the organic matter and to the exchangeable fraction (<10%). The bioavailable fraction of the studied heavy metals exceeds 45%, which present risk of toxicity.

  2. 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. Copyright © 2011 Elsevier Ltd. All rights reserved.

  3. Distribution of P, K, Ca, Mg, Cd, Cu, Fe, Mn, Pb and Zn in wood and bark age classes of willows and poplars used for phytoextraction on soils contaminated by risk elements.

    Science.gov (United States)

    Zárubová, Pavla; Hejcman, Michal; Vondráčková, Stanislava; Mrnka, Libor; Száková, Jiřina; Tlustoš, Pavel

    2015-12-01

    Fast-growing clones of Salix and Populus have been studied for remediation of soils contaminated by risk elements (RE) using short-rotation coppice plantations. Our aim was to assess biomass yield and distributions of elements in wood and bark of highly productive willow (S1--[Salix schwerinii × Salix viminalis] × S. viminalis, S2--Salix × smithiana clone S-218) and poplar (P1--Populus maximowiczii × Populus nigra, P2--P. nigra) clones with respect to aging. The field experiment was established in April 2008 on moderately Cd-, Pb- and Zn- contaminated soil. Shoots were harvested after four seasons (February 2012) and separated into annual classes of wood and bark. All tested clones grew on contaminated soils, with highest biomass production and lowest mortality exhibited by P1 and S2. Concentrations of elements, with exception of Ca and Pb, decreased with age and were higher in bark than in wood. The Salix clones were characterised by higher removal of Cd, Mn and Zn compared to the Populus clones. Despite generally higher RE content in young shoots, partly due to lower wood/bark ratios and higher RE concentrations in bark, the overall removal of RE was higher in older wood classes due to higher biomass yield. Thus, longer rotations seem to be more effective when phytoextraction strategy is considered. Of the four selected clones, S1 exhibited the best removal of Cd and Zn and is a good candidate for phytoextraction.

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

    NARCIS (Netherlands)

    Fan, Zhaochuan; Koster, Rik S.; Wang, Shuaiwei; Fang, Changming; Yalcin, Anil O.; Tichelaar, Frans D.; Zandbergen, Henny W.; van Huis, Marijn A.; Vlugt, Thijs J. H.

    2014-01-01

    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

  5. 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.

  6. Structural and luminescence studies of Eu3+: TeO2sbnd B2O3sbnd AOsbnd AF2 (A = Pb, Ba, Zn, Cd, Sr) glasses

    Science.gov (United States)

    Selvi, S.; Marimuthu, K.; Muralidharan, G.

    2017-09-01

    Eu3+ doped oxyfluoro boro-tellurite (TBXFE) with molar composition 29 TeO2sbnd 30B2O3sbnd 20AOsbnd 20AF2sbnd 1Eu2O3 (where A = Pb, Ba, Zn, Cd, Sr) glasses were prepared and investigated by XRD, FTIR, UV-Vis-NIR, luminescence and decay measurements. XRD patterns confirm the glassy nature of the prepared glasses. The influence of metal ions on the structure of boro-tellurite glasses were investigated through FTIR spectra. The intra band (4f-4f) transitions of Eu3+ ions are discussed through UV-Vis-NIR absorption spectra. The covalent nature around the Eu3+ ions with ligands are discussed using the bonding parameter (δ) and nephelauxetic ratio (β). The fundamental absorption edge, direct, indirect band gap, Urbach energy and band tailing parameters are reported. A bright red emission at 616 nm corresponding to the 5D0 → 7F2 transition of Eu3+ ions could be observed in the title glasses. Judd-Ofelt parameters were estimated from the emission spectra of Eu3+ ions. The dependence of these parameters on the composition of the glass is discussed. Judd-Ofelt parameters were used to derive the radiative parameters such as transition probabilities (A, s-1), branching ratios (βR), radiative lifetime (τrad) and stimulated emission cross-section (σPE) for the 5D0 → 7FJ (J = 0, 1, 2, 3 and 4) transitions. The luminescence intensity ratio (LIR) of 5D0 → 7F2/5D0 → 7F1 transitions was estimated to analyze the local site symmetry around the Eu3+ ions in the present glasses. The chromaticity coordinates and colour purity were calculated from the emission spectra and analyzed with Commission International de I'Eclairage (CIE) 1931 diagram. The experimental lifetime of 5D0 level could be fitted to a single exponential indicating the absence of energy transfer between the Eu3+ ions in the present glasses.

  7. Etude d’impact des métaux traces (Hg, Cd, Pb, Cu et Zn) dans les cystes et la biomasse "d’Artemia" exploités dans la saline de Sfax

    OpenAIRE

    Aloui, N.; Amorri, M.; Choub., L.

    2010-01-01

    RESUME La saline de Sfax constitue un site potentiel pour l’exploitation et la production de l’Artemia locale. Des quantités importantes d’Artemia sont exploitées chaque année (60 kg de cystes poids sec) et sont utilisées en alimentation larvaire. Afin de démontrer l’impact de divers rejets industriels, agricoles dans cette saline, nous avons procédé à la détermination de quelques métaux traces toxiques : le mercure (Hg), le cadmium (Cd), le plomb (Pb), le cuivre (Cu) et le zinc (Zn) p...

  8. Genotoxicity and cytotoxicity response to environmentally relevant complex metal mixture (Zn, Cu, Ni, Cr, Pb, Cd) accumulated in Atlantic salmon (Salmo salar). Part I: importance of exposure time and tissue dependence.

    Science.gov (United States)

    Stankevičiūtė, Milda; Sauliutė, Gintarė; Svecevičius, Gintaras; Kazlauskienė, Nijolė; Baršienė, Janina

    2017-10-01

    Health impact of metal mixture at environment realistic concentrations are difficult to predict especially for long-term effects where cause-and-effect relationships may not be directly obvious. This study was aimed to evaluate metal mixture (Zn-0.1, Cu-0.01, Ni-0.01, Cr-0.01, Pb-0.005 and Cd-0.005 mg/L, respectively for 1, 2, 4, 7, 14 and 28 days at concentrations accepted for the inland waters in EU) genotoxicity (micronuclei, nuclear buds, nuclear buds on filament), cytotoxicity (8-shaped nuclei, fragmented-apoptotic erythrocytes), bioaccumulation, steady-state and the reference level of geno-cytotoxicity in hatchery-reared Atlantic salmon tissues. Metals accumulated mostly in gills and kidneys, to the lesser extent in the muscle. Uptake of metals from an entire mixture in the fish for 14 days is sufficient to reach steady-state Cr, Pb concentrations in all tissues; Zn, Cu-in kidneys and muscle, Ni-in liver, kidneys, muscle and Cd-in muscle. Treatment with metal mixture significantly increased summed genotoxicity levels at 7 days of exposure in peripheral blood and liver erythrocytes, at 14 days of exposure in gills and kidney erythrocytes. Significant elevation of cytotoxicity was detected after 2 and 14 days of exposure in gills erythrocytes and after 28 days-in peripheral blood erythrocytes. The amount of Cu, Cr, Pb and Cd accumulated in tissues was dependent upon duration of exposure; nuclear buds, 8-shaped nuclei frequencies also were dependent upon duration of exposure. This study indicates that metals at low levels when existing in mixture causes significant geno-cytotoxicity responses and metals bioaccumulation in salmon.

  9. The concentration of some metals (Pb, Cd, Zn and Cu) and delta aminolevulinic acid dehydratase activity of fruit fly (Drosophila melanogaster) living near lead and zinc smelter ``Trepça'' in Kosova

    Science.gov (United States)

    Elezaj, I. R.; Letaj, K. Rr.; Selimi, Q. I.; Zhushi-Etemi, F.

    2003-05-01

    The concentration of Pb, Cd, Zn and Cu, δ-aminolevulinic acid dehydratase activity (ALA-D: EC.4.2.1.24) hemoglobin and protein amount have been determined in three different populations of fruit fly (Drosophila melanogaster) caught at two urban sites (Mitrovica town, which is situated close to smelter of “Trepça” don close and Prishtina the capital of Kosova) and in Luki village as uncontaminated area. The results show that in the fruit fly of Mitrovica the concentration of Pb, Cd and Zn was significantly higher (Pfruit fly from Mitrovica was 3.1 times higher in comparison with that on fruit fly of Prishtina and 4.9 times higher in comparison with uncontaminated group of fruit fly. The ALA-D activity was significantly inhibited in the homogenate of fruit fly from Mitrovica in comparison with Prishtina and Luki localities (Pfruit fly in comparison with Luki group (Pfruit fly in comparison with that in control and Prishtina group. The hemoglobin value was relatively unchanged.

  10. 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

  11. Comparison of trace element contamination levels (Cu, Zn, Fe, Cd ...

    African Journals Online (AJOL)

    SERVER

    2008-03-18

    Mar 18, 2008 ... Chemical analysis of the trace elements in the soft tissues. The trace elements of interest (Cu, Zn, Fe, Pb, Cd) were then determined in the digested solutions, using Thermoelemental type. M6 brand of an atomic absorption Spectrometer equipped with a flame operated atomisation system and a deuterium ...

  12. Comparison of trace element contamination levels (Cu, Zn, Fe, Cd ...

    African Journals Online (AJOL)

    Comparison of trace element contamination levels (Cu, Zn, Fe, Cd and Pb) in the soft tissues of the gastropods Tympanotonus fuscatus fuscatus and Tf radula collected in the Ebrié Lagoon (Côte d'Ivoire): Evidence of the risks linked to linked to lead and.

  13. CHEMICAL SPECIATION OF Pb(II), Cd(II)

    African Journals Online (AJOL)

    Chemical speciation of Pb(II), Cd(II), Hg(II), Co(II), Ni(II), Cu(II) and Zn(II) complexes of L-methionine in 0.0-60 % v/v 1,2-propanediol-water mixtures maintaining an ionic strength of 0.16 M at 303 K has been studied pH metrically. The active forms of ligand are LH2+, LH and L-. The predominant species detected are ML, ...

  14. Relations between metals (Zn, Pb, Cd and Cu) and glutathione-dependent detoxifying enzymes in spiders from a heavy metal pollution gradient

    International Nuclear Information System (INIS)

    Wilczek, Grazyna; Babczynska, Agnieszka; Augustyniak, Maria; Migula, Pawel

    2004-01-01

    We studied the relations between glutathione-dependent detoxifying enzymes and heavy metal burdens in the web-building spider Agelena labyrinthica (Agelenidae) and the wolf spider Pardosa lugubris (Lycosidae) from five meadow sites along a heavy metal pollution gradient. We assayed the activity of glutathione-S-transferase (GST) and glutathione peroxidases (GPOX, GSTPx), and glutathione (GSH) levels in both sexes. Except for GSH vs Pb content, we found significant correlations between GPOX and GSTPx activity and metal concentrations in females of A. labyrinthica. The highest activity of these enzymes measured in the web-building spiders was found in the individuals from the most polluted sites. In P. lugubris males significant correlations were found between GST and Pb and Zn concentrations, and between GPOX and GSTPx and the concentration of Cu. GST activity was higher in males collected from less polluted areas. Thus, detoxifying strategies against pollutants seemed to be sex-dependent. Actively hunting spiders had higher metal concentrations, maintaining lower activity of detoxifying enzymes and a lower glutathione level. - Capsule: Glutathione-linked enzyme activity in spiders from polluted areas depends on hunting strategy and sex

  15. An ICP-MS procedure to determine Cd, Co, Cu, Ni, Pb and Zn in oceanic waters using in-line flow-injection with solid-phase extraction for preconcentration.

    Science.gov (United States)

    O'Sullivan, Jeanette E; Watson, Roslyn J; Butler, Edward C V

    2013-10-15

    An automated procedure including both in-line preconcentration and multi-element determination by an inductively coupled plasma mass spectrometer (ICP-MS) has been developed for the determination of Cd, Co, Cu, Ni, Pb and Zn in open-ocean samples. The method relies on flow injection of the sample through a minicolumn of chelating (iminodiacetate) sorbent to preconcentrate the trace metals, while simultaneously eliminating the major cations and anions of seawater. The effectiveness of this step is tested and reliability in results are secured with a rigorous process of quality assurance comprising 36 calibration and reference samples in a run for analysis of 24 oceanic seawaters in a 6-h program. The in-line configuration and procedures presented minimise analyst operations and exposure to contamination. Seawater samples are used for calibration providing a true matrix match. The continuous automated pH measurement registers that chelation occurs within a selected narrow pH range and monitors the consistency of the entire analytical sequence. The eluent (0.8M HNO3) is sufficiently strong to elute the six metals in 39 s at a flow rate of 2.0 mL/min, while being compatible for prolonged use with the mass spectrometer. Throughput is one sample of 7 mL every 6 min. Detection limits were Co 3.2 pM, Ni 23 pM, Cu 46 pM, Zn 71 pM, Cd 2.7 pM and Pb 1.5 pM with coefficients of variation ranging from 3.4% to 8.6% (n=14) and linearity of calibration established beyond the observed concentration range of each trace metal in ocean waters. Recoveries were Co 96.7%, Ni 102%, Cu 102%, Zn 98.1%, Cd 92.2% and Pb 97.6%. The method has been used to analyse ~800 samples from three voyages in the Southern Ocean and Tasman Sea. It has the potential to be extended to other trace elements in ocean waters. © 2013 Elsevier B.V. All rights reserved.

  16. THE EFFECT OF PVC-BASED MEMBRANE COMPOSITION AND Zn(II, Cd(II AND Pb(II INTERFERING IONS TO Hg(II ION SELECTIVE ELECTRODE (ISE PERFORMANCE BY USING DBA218C6 IONOPHORE

    Directory of Open Access Journals (Sweden)

    Abd. Wahid Wahab

    2010-06-01

    Full Text Available The effect of PVC (Polyvinylchloride-Based Membrane Composition to Ion Selective Electrode (ISE-Hg(II Performance using Ionophore DBA218C6 (N,N'-Dibenzyl-1,4,10,13-tetraoxa-7,16-diazacyclo octadecane,  Plasticizer NPOE (Nitrophenyl Octhyl Ether, Anionic Site KTCPB (Potassium Tetrakis (4-chloro phenyl borate have been performed. Membrane compositions used were:(a PVC (30 mg, NPOE (60 mg, DBA218C6(6 mg and KTCPB (4 mg; (b PVC(30 mg, NPOE (60 mg, DBA218C6(7 mg and KTCPB (3 mg; (c PVC (30 mg, NPOE (59 mg, DBA218C6 (8 mg and KTCPB( 3 mg. The concentration range of interference ions Zn(II, Cd(II and Pb(II  were 1.0 x 10-3 - 1.0 x 10-1 M. ISE-Hg(II performance for membrane composition of 30 : 60 : 6 : 4 was 26.34 mV per decade (Nernstian Slope value on Hg(II concentration range of 1.0x10-6 - 1.0 x 10-1 M , membrane composition of 30 : 60 : 7 : 3 was 27.71 mV per decade on Hg(II concentration range of 1.0 x10-6 - 1.0 x10-1 M, and membrane composition of 30 : 59 : 8 : 3 was 28.52 mV per decade on Hg(II concentration range of  1.0 x10-6 - 1.0 x10-1 M with activity between pH 1.0-3.0. The concentration of interference ions : Zn(II, Cd(II and Pb(II in the range of 1.0 x 10-3 - 1.0 x 10-1 M with the ratio of the primary ion to interference ions of 4 : 1 gave real effect. As results, selectivities and sensitivities between ISE-Hg(II and Ionophore DBA218C6 could be determined by PVC-Based Membrane Composition and the effect of Zn(II, Cd(II and Pb(II  interference ions was observed in the concentration of 1,0 x10-3 - 1,0 x10-1 M.   Keywords: membrane composition effect, ionophore DBA218C6, ISE-Hg(II

  17. Suitability of three cultivars of coral bells (heuchera cvs. to bioremediation of cadmium (cd, lead (pb and zinc (zn from post-mining area in zagłębie dąbrowskie

    Directory of Open Access Journals (Sweden)

    Gabriela Sąkol

    2011-09-01

    Full Text Available Background: Long-term shallow exploitation of pitcoal in Będzin area (in mining district Zagłębie Dąbrowskie has degraded the environment. Profiles of soil were dislocated and contaminated with heavy metals above permissible standards. Due to the fact that Zagłę- bie Dąbrowskie is densely populated, risk of harmful exposure to heavy metals affects high number of people. Decontamination of post-mining grounds is possible with planting plants which not only tolerate elevated heavy metals quantities but can also accumulate them in plant tissues. Materials and methods: The cultivars ‘Chatterbox’ and ‘Strawberry Swirl’ and ‘Palace Purple’ of coral bells (Heuchera cvs. were chosen to do the research. Cadmium, lead and zinc uptake in plants growing in contaminated and control fields was evaluated. Amount of heavy metals was determined by atomic absorption spectrometry (AAS. Results: Content of metals detected in plants in postmining soil was respectively: Cd 1,92 mgükg11, Pb 56,3 mgükg11, Zn 153,7 mgükg11. Those metals value is from 2 to 4 times higher than natural content in neutral soil of pH 6,5 – a typical pH in this region. The examined cultivars of coral bells accumulated significant amount of Cd, Pb, Zn even if concentration of those metals was low, what is characteristic for clean regions of Poland. Conclusions: The plants cultivated on contaminated soil of post-mining region didn`t show toxic response (damaged leaves even though they accumulated cadmium, lead and zinc in their roots and leaves. Cultivars differences of coral bells found on significance level (p¤0,05. The cultivar ‘Palace Purple’ has transported the highest amount of lead from roots to leaves. Other cultivars ‘Chatterbox’ and ‘Strawberry Swirl’ have accumulated higher amounts of metals in their roots in a sequence Cd¤Zn¤Pb.

  18. Availability of heavy metals (Cd, Pb, And Cr) in agriculture from commercial fertilizers.

    Science.gov (United States)

    Nacke, H; Gonçalves, A C; Schwantes, D; Nava, I A; Strey, L; Coelho, G F

    2013-05-01

    The purpose of this study was to investigate the availability of the heavy metals cadmium (Cd), lead (Pb), and chromium (Cr) to soil and maize plants fertilized with different sources and doses of zinc (Zn) in a Rhodic Eutrudox soil. For that purpose, concentrations of Cd, Pb, and Cr were evaluated in leaf tissue and grains of maize plants and in 0-20 and 20-40 cm soil layers after fertilization with four doses of Zn from eight different sources of fertilizer. There was no accumulation of Cd, Pb, and Cr in maize grain and Cd and Cr in leaf tissue of the plants; nevertheless, there was accumulation of Pb in leaf tissue, showing its availability throughout different sources of Zn and consequent uptake by plants. Regarding the soil, it was observed that fertilizer from the different sources made Cd, Pb, and Cr available at increasing amounts proportional to increased Zn doses. Under experimental conditions, fertilization with Zn increased concentrations of heavy metals Cd, Pb and Cr in soil, further highlighting the importance of conducting more studies related to the application of mineral fertilizers for micronutrient supply and the availability of heavy metals.

  19. Chemical speciation of Pb(II, Cd(II, Hg(II, Co(II, Ni(II, Cu(II and Zn(II binary complexes of l-methionine in 1,2-propanediol-water mixtures

    Directory of Open Access Journals (Sweden)

    M. Padma Latha

    2007-04-01

    Full Text Available Chemical speciation of Pb(II, Cd(II, Hg(II, Co(II, Ni(II, Cu(II and Zn(II complexes of L-methionine in 0.0-60 % v/v 1,2-propanediol-water mixtures maintaining an ionic strength of 0.16 M at 303 K has been studied pH metrically. The active forms of ligand are LH2+, LH and L-. The predominant species detected are ML, MLH, ML2, ML2H, ML2H2 and MLOH. Models containing different numbers of species were refined by using the computer program MINIQUAD 75. The best-fit chemical models were arrived at based on statistical parameters. The trend in variation of complex stability constants with change in the dielectric constant of the medium is explained on the basis of electrostatic and non-electrostatic forces.

  20. Synthesis of high-surface-area γ-Al2O3 from aluminum scrap and its use for the adsorption of metals: Pb(II), Cd(II) and Zn(II)

    International Nuclear Information System (INIS)

    Asencios, Yvan J.O.; Sun-Kou, María R.

    2012-01-01

    Highlights: ► Aluminum hydroxide obtained from aluminum scrap led to the formation of gamma alumina. ► Acidic pH of precipitation favored the formation of small particles of high surface areas. ► Higher aging temperature favored the formation of large structures of large pore sizes. ► Higher aging temperature generated symmetrical solids of regular hexagonal prism forms. ► Aluminas of large pores adsorbed metals as following: Pb (1.75 Å) > Cd (1.54 Å) > Zn (1.38 Å). - Abstract: Several types of alumina were synthesized from sodium aluminate (NaAlO 2 ) by precipitation with sulfuric acid (H 2 SO 4 ) and subsequently calcination at 500 °C to obtain γ-Al 2 O 3 . The precursor aluminate was derived from aluminum scrap. The various γ-Al 2 O 3 synthesized were characterized by Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), adsorption–desorption of N 2 (S BET ) and scanning electron microscopy (SEM). XRD revealed that distinct phases of Al 2 O 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 2 g −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.

  1. 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)

    Planchon, F.

    2001-01-01

    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)

  2. Competition from Cu(II), Zn(II) and Cd(II) in Pb(II) binding to Suwannee River Fulvic Acid

    NARCIS (Netherlands)

    Chakraborty, P.; Chakrabarti, C.L.

    2008-01-01

    This is a study of trace metal competition in the complexation of Pb(II) by well-characterized humic substances, namely Suwannee River Fulvic Acid (SRFA) in model solutions. It was found that Cu(II) seems to compete with Pb(II) for strong binding sites of SRFA when present at the same concentration

  3. 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.

  4. 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%.

  5. Respon Bioakumulator Eceng Gondok (Eichhornia crassipes Terhadap Logam Berat Pb dan Cd di Sungai Pegangsaan Dua

    Directory of Open Access Journals (Sweden)

    Sri Teguh Rahayu

    2014-04-01

    Full Text Available Eichhornia crassipes is one of Indonesia’s wild plant considered as weed. Its presence can disrupt ecosystems in the river. However, it is proven to absorb Pb and Fe. It is also believed that E. crassipescan absorb other metals such as Hg, Zn, Cu and Cd which were belong to the same group as Pb and Fe. In addition to heavy metal sequestration, Eichhornia crassipes can also absorb pesticide residues. This descriptive research was done to determine the bioaccumulator response to Pb and Cd in Pegangsaan Dua river using Inductively Coupled Plasma method. Bioaccumulator response of Eichhornia crassipes were analyzed from the stem. The results of the study also showed that the Eichhornia crassipes plants were able to accumulate heavy metals of Pb and Cd. The organs most potential to absorb Cd and Pb were stem organ with average point 1 of Cd: 0,056 ppm and Pb: 0,5002 ppm, then the average point 2 of Cd: 0,0328 ppm and Pb: 0,0215 ppm, and the average point 3 of Cd: 0.0143 ppm and Pb: 1,293 ppm. In the end, it is suggested that the stem organ could be developed as bioaccumulation agent.

  6. Synthesis and characterization of sulfur functionalized graphene oxide nanosheets as efficient sorbent for removal of Pb2+, Cd2+, Ni2+ and Zn2+ ions from aqueous solution: A combined thermodynamic and kinetic studies

    Science.gov (United States)

    Pirveysian, Mahtab; Ghiaci, Mehran

    2018-01-01

    A very simple, one pot method was used for preparation of sulfur functionalized graphene oxide (GO-SOxR) with sodium sulfide and water in reflux condition. The elemental analysis data showed high sulfur content up to 15%. EDS and XPS analysis also proved introduction of sulfur element. To make the sorbent more efficient operationally, the GO-SOxR was coated with a mesoporous shell of TiO2 or SiO2. The prepared sorbents were characterized by SEM, TEM, TGA, XPS, XRD, IR and EDS. GO-SOxR@TiO2 and GO-SOxR@SiO2 composites were tested for removal of Pb(II), Cd(II), Ni(II) and Zn(II) as heavy metal ions from aqueous solution in batch method. Adsorption of the heavy metal ions was studied kinetically, and the adsorption capacities of GO-SOxR, GO-SOxR@TiO2, and GO-SOxR@SiO2 were evaluated using equilibrium adsorption isotherms, and compared to other adsorbents used for removal of these heavy metals. Kinetic studies showed that the experimental data was fitted with pseudo second order model. The adsorption capacity of GO was significantly improved by sulfur functionalization and TiO2 coating.

  7. Adsorption of Cu(II), Zn(II), Cd(II) and Pb(II) by dead Avena fatua biomass and the effect of these metals on their growth.

    Science.gov (United States)

    Areco, María Mar; Saleh-Medina, Leila; Trinelli, María Alcira; Marco-Brown, Jose Luis; Dos Santos Afonso, María

    2013-10-01

    The biosorption of copper(II), zinc(II), cadmium(II) and lead(II) from aqueous solutions by dead Avena fatua biomass and the effect of these metals on the growth of this wild oat were investigated. Pseudo-first- and second-order and intra-particle diffusion models were applied to describe the kinetic data and to evaluate the rate constants. The adsorption kinetics of all the metals follows a pseudo-second-order model. The adsorption capacity was determined, and the Freundlich and Langmuir models were applied. The experimental data obtained for all the metals are best described by the Langmuir model. A. fatua was characterized using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and zeta potential. The results obtained evidence the presence of Zn(II), Cu(II), Cd(II) or Pb(II) on the surface of the weed. The growth of A. fatua was affected by the presence of all metals. The decrease in the growth rate with increasing metal concentration was more noticeable for zinc. Copyright © 2013 Elsevier B.V. All rights reserved.

  8. Nuclear and related analytical methods applied to the determination of Cr, ni, Cu, Zn, cd and Pb during the studies of distribution of the metals between ferralitic - red soil and sorgo Plant

    International Nuclear Information System (INIS)

    Estevez Alvarez, J.R.; Montero Alvarez, A.; Jimenez Napoles, H.; Aguiar Lambert, D.; Pupo Gonzalez, I.; Frias Fonseca, D.; Padilla Alvarez, R.; Munniz Ugarte, O.; Molina Rodriguez, J.; Quicute de Vera, S.; Vega Tamayo, E.

    1999-01-01

    Several studies about the influence of heavy metals onto the growth of vegetables have been carried out in Cuba by the Ministry of Agriculture with the aim to evaluate the effects resulting of the continuous application of fertilizers and other materials to the crop soils. The analysis of metal contents in soil and vegetable samples is often troublesome due to the low concentration levels to be determined. During the present work different EDXRF, AAS and ASV methods were applied and compared for the evaluation of Cr, Ni, Cu, Zn, Cd and Pb contents in ferralitic -red soil and sorgo plant 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 growing sorgo plants 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 resulting after such experiment, as well as the influence of different additions of each metal onto the plant growth is also presented

  9. Preparation and Spectral Properties of Mixed-Ligand Complexes of VO(IV, Ni(II, Zn(II, Pd(II, Cd(II and Pb(II with Dimethylglyoxime and N-acetylglycine

    Directory of Open Access Journals (Sweden)

    Shayma A. Shaker

    2010-01-01

    Full Text Available A number of mixed-ligand complexes of the general formula [M(D(G] where D=dimethylglyoximato monoanion, G=N-acetylglycinato and M=VO(IV, Ni(II, Zn(II, Pd(II, Cd(II and Pb(II were prepared. Each complex was characterized by elemental analysis, determination of metal, infrared spectra, electronic spectra, (1H and 13C NMR spectra, conductivity and magnetic moments. All these complexes were not soluble in some of the organic solvent but highly soluble in dimethylformamide. The conductivity data showed the non-electrolytic nature of the complexes. The electronic spectra exhibited absorption bands in the visible region caused by the d-d electronic transition such as VO(IV, Ni(II and Pd(II. The IR and (1H, 13C NMR spectra which have indicate that the dimethylglyoxime was coordinated with the metal ions through the N and O atoms of the oxime group and N-acetylglycine was coordinated with metal ions through the N atom and terminal carboxyl oxygen atom.

  10. 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

    Energy Technology Data Exchange (ETDEWEB)

    Joubert, A.V.P. [Laboratoire des Interactions Micro-organismes, Mineraux et Matieres organiques dans les Sols (LIMOS) UMR 7137, Nancy University, CNRS, BP 239, 54506 Vandoeuvre-les-Nancy cedex (France)]. E-mail: antoine.joubert@limos.uhp-nancy.fr; Lucas, L. [Bureau de Recherches Geologiques et Minieres (BRGM), Service Environnement et Procedes Innovants-Unite Ecotechnologie (EPI/ECO), 3 Avenue Claude Guillemin, BP 6009, 45060 Orleans cedex 2 (France); Garrido, F. [Bureau de Recherches Geologiques et Minieres (BRGM), Service Environnement et Procedes Innovants-Unite Ecotechnologie (EPI/ECO), 3 Avenue Claude Guillemin, BP 6009, 45060 Orleans cedex 2 (France)]. E-mail: f.garrido@brgm.fr; Joulian, C. [Bureau de Recherches Geologiques et Minieres (BRGM), Service Environnement et Procedes Innovants-Unite Ecotechnologie (EPI/ECO), 3 Avenue Claude Guillemin, BP 6009, 45060 Orleans cedex 2 (France); Jauzein, M. [Laboratoire des Interactions Micro-organismes, Mineraux et Matieres organiques dans les Sols (LIMOS) UMR 7137, Nancy University, CNRS, BP 239, 54506 Vandoeuvre-les-Nancy cedex (France)

    2007-08-15

    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.

  11. Solvent extraction of Ca2+, Ba2+, Cu2+, Zn2+, Cd2+, Pb2+, UO22+, Mn2+, Co2+ and Ni2+ into nitrobenzene using strontium dicarbol-lylcobaltate and tetra-tert-butyl p-tert-butylcalix[4]arene tetraacetate

    Directory of Open Access Journals (Sweden)

    E. MAKRLÍK

    2008-12-01

    Full Text Available The exchange extraction constants corresponding to the general equilibrium M2+(aq + SrL2+(nb D ML2+ (nb + Sr2+ (aq occurring in the two-phase water–nitrobenzene system (M2+ = Ca2+, Ba2+, Cu2+, Zn2+, Cd2+, Pb2+, UO22+, Mn2+, Co2+ or Ni2+; L = tetra-tert-butyl p-tert-butylcalix[4]arene tetraacetate; aq = aqueous phase; nb = nitrobenzene phase were evaluated from extraction experiments and -activity measurements. Furthermore, the stability constants of the ML2+ complexes in water saturated nitrobenzene were calculated; they were found to increase in the cation order Ba2+ < Mn2+ < Pb2+, Co2+ < Cu2+, Zn2+ < Cd2+, Ni2+ < UO22+ < Ca2+.

  12. Lime and Phosphate Amendment Can Significantly Reduce Uptake of Cd and Pb by Field-Grown Rice

    OpenAIRE

    Rongbo Xiao; Zehong Huang; Xiaonuo Li; Weiping Chen; Yirong Deng; Cunliang Han

    2017-01-01

    Agricultural soils are suffering from increasing heavy metal pollution, among which, paddy soil polluted by heavy metals is frequently reported and has elicited great public concern. In this study, we carried out field experiments on paddy soil around a Pb-Zn mine to study amelioration effects of four soil amendments on uptake of Cd and Pb by rice, and to make recommendations for paddy soil heavy metal remediation, particularly for combined pollution of Cd and Pb. The results showed that all ...

  13. Accumulation of Pb, Cd and Zn from contaminated soil to various plants and evaluation of soil remediation with indicator plant (Plantago lanceolata L.)

    Energy Technology Data Exchange (ETDEWEB)

    Zupan, M.; Lobnik, F.; Kadunc, V. [Ljubljana Univ. (Slovenia). Agronomy Dept., Center for Soil and Environmental Science; Hudnik, V. [National Institute of Chemistry Hajdrihova 19, Ljubljana (Slovenia)

    1997-12-31

    The accumulation of cadmium, lead, and zinc by different major cultivated plants from soils contaminated with heavy metals, is presented. The vegetables, crops, and the indicator plant narrow leaf plantain (Plantago lanceolata L.) were used in a field experiment including 3 areas with different levels of pollution. The highest concentrations of heavy metals were observed in edible green parts of vegetables (endive, spinach, lettuce) and roots (carrot, red beet, radish). The heavy metal content in leguminous plants (pods and seeds) was very low compared to high soil concentrations. Wheat and maize showed lower concentrations in grains and kernels than in green parts. Lime and vermiculite were used for reduction of Cd availability to plants in polluted soil. The Cd concentration decreased in the narrow leaf plantain in the presence of both lime and vermiculite in acid soil. In the higher-pH soil the Cd availability to spinach was greatly reduced in the presence of vermiculite

  14. Heavy metal / polyacid interaction : an electrochemical study of the binding of Cd(II), Pb(II) and Zn(II) to polycarboxylic and humic acids

    NARCIS (Netherlands)

    Cleven, R.F.M.J.

    1984-01-01

    Polyelectrolyte effects in the interaction of heavy metal ions with model polycarboxylic acids have been described, in order to establish the relevance of these effects in the interaction of heavy metal ions with naturally occurring humic and fulvic acids. The model systems consisted of Cd(II),

  15. 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.

  16. USO DO PLANEJAMENTO EXPERIMENTAL PARA OTIMIZAÇÃO DE UM PROCEDIMENTO VOLTAMÉTRICO PARA DETERMINAÇÃO SIMULTÂNEA DAS CONCENTRAÇÕES DOS METAIS Zn, Cd, Pb E Cu LIVRES EM ÁGUA DE COCO

    Directory of Open Access Journals (Sweden)

    Thalles R. Rosa

    2016-02-01

    Full Text Available Optimization of the main parameters of SWASV using boron-doped diamond electrode was described for the simultaneous determination of Zn, Cd, Pb and Cu free in coconut water. The values of electroanalytical parameters studied were optimized with the factorial design and center composite design. The optimized parameters for the preconcentration of metals were -1.50 V for potential, and 240 s for deposition time. For SWV, the optimized value was 11.56 mV for step potential. In addition, frequency and pulse height were defined at 100 Hz and 55 mV, respectively. Furthermore, the concentration of the supporting electrolyte (acetate buffer, pH 4.7 was optimized in 0.206 mol L-1. The optimized procedure was applied in two samples of coconut water: natural and processed. The limits of detection (LOD obtained for Zn, Cd, Pb and Cu were 7.2; 4.4; 3.3 and 1.5 µg L-1, respectively. The concentrations of Cd and Pb were not detected. On the other hand, the values found for the concentrations of Zn and Cu were: < LOD (29 µg L-1 and (6.8 ± 0.9 µg L-1 for the natural sample; and (85.8 ± 4.2 µg L-1 and (7.7 ± 0.6 µg L-1 for the processed sample, respectively.

  17. 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

    2015-10-14

    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).

  18. Synthesis and characterization of ZnO/ZnSe NWs/PbS QDs solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Kamruzzaman, M, E-mail: kzaman.phy11@gmail.com; Zapien, J A, E-mail: apjazs@cityu.edu.hk [City University of Hong Kong, Department of Physics and Materials Science and Center Of Super-Diamond and Advanced Films (COSDAF) (China)

    2017-04-15

    The capture of solar energy has gained the attention for the next generation solar cell. ZnO/ZnSe NW arrays were synthesized on an FTO glass substrate using a simple and facile hydrothermal and ion-exchange approaches. The lead sulfide (PbS) QDs was infiltrated into ZnO/ZnSe NWs via SILAR method for making inorganic quantum dot sensitized ZnO/ZnSe/PbS QDs solar cell. The surface morphology, structural, optical, and J-V characteristics have been investigated. The ZnO/ZnSe NW is a core–shell like structure, and the absorption edge shifted from the UV region (ZnO NWs) to the near infrared region for ZnO/ZnSe NWs/PbS QDs. For PbS QDs-sensitized solar cell, the obtained value of η = 1.1%, J{sub sc} = 20.60 mA/cm{sup 2}, V{sub oc} = 155 mV, and FF = 34.7%, respectively. The photovoltaic performance of the device in this study is still inferior. However, it is the first report regarding to ZnO/ZnZe NWs/PbS QDs solar cell. The achieving high absorption and large short circuit current density may interest in further improvement of the device performance by suppressing surface defects, optimizing the quality of ZnO/ZnSe NWs and PbS QDs.

  19. EXPLORING POSSIBILITIES OF CULTIVATION A UNPOLLUTED PLANT PRODUCE IN Pb AND Cd CONTAMINATED SITES

    Directory of Open Access Journals (Sweden)

    Atanas TOMOV

    2006-02-01

    Full Text Available The control of heavy metals in such way that soil function and product quality are not impeded is a prerequisite to sustainable agriculture. Growing anthropogenic fl uxes of toxic heavy metals in agro-ecosystems affect on purity of farm products and soil fertility. In the article we describe a fi eld experiment – cultivation of potatoes on soil with a medium level of pollution / Zn, Cu, Pb, Cd etc/. We studied the most toxic of them – Pb and Cd; as well as the possibilities for reducing their phytoavailability and accumulation in potatoes tubers, applying soil amendments.

  20. Soil heavy metal pollution and risk assessment associated with the Zn-Pb mining region in Yunnan, Southwest China.

    Science.gov (United States)

    Cheng, Xianfeng; Danek, Tomas; Drozdova, Jarmila; Huang, Qianrui; Qi, Wufu; Zou, Liling; Yang, Shuran; Zhao, Xinliang; Xiang, Yungang

    2018-03-07

    The environmental assessment and identification of sources of heavy metals in Zn-Pb ore deposits are important steps for the effective prevention of subsequent contamination and for the development of corrective measures. The concentrations of eight heavy metals (As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn) in soils from 40 sampling points around the Jinding Zn-Pb mine in Yunnan, China, were analyzed. An environmental quality assessment of the obtained data was performed using five different contamination and pollution indexes. Statistical analyses were performed to identify the relations among the heavy metals and the pH in soils and possible sources of pollution. The concentrations of As, Cd, Pb, and Zn were extremely high, and 23, 95, 25, and 35% of the samples, respectively, exceeded the heavy metal limits set in the Chinese Environmental Quality Standard for Soils (GB15618-1995, grade III). According to the contamination and pollution indexes, environmental risks in the area are high or extremely high. The highest risk is represented by Cd contamination, the median concentration of which exceeds the GB15618-1995 limit. Based on the combination of statistical analyses and geostatistical mapping, we identified three groups of heavy metals that originate from different sources. The main sources of As, Cd, Pb, Zn, and Cu are mining activities, airborne particulates from smelters, and the weathering of tailings. The main sources of Hg are dust fallout and gaseous emissions from smelters and tailing dams. Cr and Ni originate from lithogenic sources.

  1. 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.

  2. Contamination of arctic Fjord sediments by Pb-Zn mining at Maarmorilik in central West Greenland

    DEFF Research Database (Denmark)

    Perner, Kerstin; Leipe, Thomas; Dellwig, O

    2010-01-01

    This study focuses on heavy metal contamination of arctic sediments from a small Fjord system adjacent to the Pb-Zn "Black Angel" mine (West Greenland) to investigate the temporal and spatial development of contamination and to provide baseline levels before the mines re-opening in January 2009....... For this purpose we collected multi-cores along a transect from Affarlikassaa Fjord, which received high amounts of tailings from 1973 to 1990, to the mouth of Qaumarujuk Fjord. Along with radiochemical dating by Pb-210 and Cs-137, geochemical analyses of heavy metals (e.g. As, Cd, Hg, Pb, and Zn) were carried out....... Maximum contents were found at 12 cm depth in Affarlikassaa. After 17 years the mine last closed, specific local hydrographic conditions continue to disperse heavy metal enriched material derived from the Affarlikassaa into Qaumarujuk. Total Hg profiles from multi-cores along the transect clearly...

  3. Behavioural and biochemical responses to metals tested alone or in mixture (Cd-Cu-Ni-Pb-Zn) in Gammarus fossarum: From a multi-biomarker approach to modelling metal mixture toxicity.

    Science.gov (United States)

    Lebrun, Jérémie D; Uher, Emmanuelle; Fechner, Lise C

    2017-12-01

    Metals are usually present as mixtures at low concentrations in aquatic ecosystems. However, the toxicity and sub-lethal effects of metal mixtures on organisms are still poorly addressed in environmental risk assessment. Here we investigated the biochemical and behavioural responses of Gammarus fossarum to Cu, Cd, Ni, Pb and Zn tested individually or in mixture (M2X) at concentrations twice the levels of environmental quality standards (EQSs) from the European Water Framework Directive. The same metal mixture was also tested with concentrations equivalent to EQSs (M1X), thus in a regulatory context, as EQSs are proposed to protect aquatic biota. For each exposure condition, mortality, locomotion, respiration and enzymatic activities involved in digestive metabolism and moult were monitored over a 120h exposure period. Multi-metric variations were summarized by the integrated biomarker response index (IBR). Mono-metallic exposures shed light on biological alterations occurring at environmental exposure levels in gammarids and depending on the considered metal and gender. As regards mixtures, biomarkers were altered for both M2X and M1X. However, no additive or synergistic effect of metals was observed comparing to mono-metallic exposures. Indeed, bioaccumulation data highlighted competitive interactions between metals in M2X, decreasing subsequently their internalisation and toxicity. IBR values indicated that the health of gammarids was more impacted by M1X than M2X, because of reduced competitions and enhanced uptakes of metals for the mixture at lower, EQS-like concentrations. Models using bioconcentration data obtained from mono-metallic exposures generated successful predictions of global toxicity both for M1X and M2X. We conclude that sub-lethal effects of mixtures identified by the multi-biomarker approach can lead to disturbances in population dynamics of gammarids. Although IBR-based models offer promising lines of enquiry to predict metal mixture toxicity

  4. Should legislation regarding maximum Pb and Cd levels in human food also cover large game meat?

    Science.gov (United States)

    Taggart, Mark A; Reglero, Manuel M; Camarero, Pablo R; Mateo, Rafael

    2011-01-01

    Game meat may be contaminated with metals and metalloids if animals reside in anthropogenically polluted areas, or if ammunition used to kill the game contaminates the meat. Muscle tissue from red deer and wild boar shot in Ciudad Real province (Spain) in 2005-06 was analysed for As, Pb, Cu, Zn, Se and Cd. Samples were collected from hunting estates within and outside an area that has been historically used for mining, smelting and refining various metals and metalloids. Meat destined for human consumption, contained more Pb, As and Se (red deer) and Pb (boar) when harvested from animals that had resided in mined areas. Age related accumulation of Cd, Zn and As (in deer) and Cd, Cu and Se (in boar) was also observed. Two boar meat samples contained high Pb, at 352 and 2408 μg/g d.w., and these were likely to have been contaminated by Pb ammunition. Likewise, 19-84% of all samples (depending on species and sampling area) had Pb levels > 0.1 μg/g w.w., the EU maximum residue level (MRL) for farm reared meat. Between 9 and 43% of samples exceeded comparable Cd limits. Such data highlight a discrepancy between what is considered safe for human consumption in popular farmed meat (chicken, beef, lamb), and what in game may often exist. A risk assessment is presented which describes the number of meals required to exceed current tolerable weekly intakes (PTWIs) for Pb and Cd, and the potential contribution of large game consumption to such intake limit criteria. Copyright © 2010 Elsevier Ltd. All rights reserved.

  5. Cumulation of Cu, Zn, Cd, and Mn in Plants of Gardno Lake

    Directory of Open Access Journals (Sweden)

    Trojanowski J.

    2013-04-01

    Full Text Available In the present paper there have been shown the results of research on yhe content of Zn, Cd, Cu, Mn and Pb in chosen plants of Lake Gardno.The biggest concentration of those metals has been observed in Potamogton natans and Elodea canadensis, on average Zn – 34.9, Pb -2.77, Cd – 0.62, Cu – 3.24 and Mn – 257.4 μg g-1. It has been found that the over-ground parts of the plants under analysis cumulate several times less of heavy metals than their roots. The determined enrichment factors enabled the researchers to state that Cu in the examined plants is of natural origin while Mn, Cd and Zn – of anthropogenic origin.

  6. The Enrichment and Transfer of Heavy Metals for Two Ferns in Pb-Zn Tailing

    Directory of Open Access Journals (Sweden)

    Mai Jiajie

    2017-01-01

    Full Text Available The enrichment and transfer of 8 heavy metals of Equisetum ramosissimum and Pteris vittata growing naturally close to edge of the sewage pool in Bencun Pb-Zn Tailing, Eastern Guangdong were investigated. The results indicated that the pollution of Cd, Pb, Hg, Zn was very severe in this tailing, followed by Cu and Mn. The potential ecological risk of heavy metals was assessed to be very strong based on soil background values of Guangdong Province and at high risk according to criteria of the second grade State Soil Environmental Quality Standard, and Cd, Hg, Pb were the main factors leading to potential ecological risk. The content of 8 heavy metals in the two ferns did not reach critical content of hyperaccumulator, so neither of them was typical hyperaccumulator, but both had a certain tolerance to these heavy metal pollution. Underground parts of Pteris vittata had an enrichment coefficient above 1 and that of Equisetum ramosissimum had a value near 1, therefore the two ferns could be utilized as potential enrichment plants. The two ferns have strong adaptability to the tailing habitat and can be used as pioneers in ecological restoration of Pb-Zn tailings.

  7. where M = Pb, Sr, Zn, Ca

    Indian Academy of Sciences (India)

    Administrator

    Detailed variable temperature Mössbauer, infrared, EXAFS spectroscopic measurements and variable temperature magnetic susceptibility experiments were carried out on. K2PbFe(NO2)6 to investigate the electronic structure and correlate it to the observed unusual magnetic hyperfine interaction in the system. All these ...

  8. Bioaccumulation of Zn and Pb in Avicennia marina (Forsk.) Vierh ...

    African Journals Online (AJOL)

    Accumulation of heavy metals (Zn, Pb) was studied in two mangrove species Avicennia marina (Forsk.)Vierh. and Sonneratia apetala Buch.Ham. under field conditions. Variation in concentration of metals was found in leaf, root and sediment samples of these two species from different localities. Both the species of ...

  9. Bioaccumulation of Zn and Pb in Avicennia marina (Forsk.) Vierh ...

    African Journals Online (AJOL)

    MICHAEL

    ABSTRACT: Accumulation of heavy metals (Zn, Pb) was studied in two mangrove species Avicennia marina. (Forsk.)Vierh. and Sonneratia apetala Buch.Ham. under field conditions. Variation in concentration of metals was found in leaf, root and sediment samples of these two species from different localities. Both the ...

  10. Examples from the Greenland-Project - Gentle Remediation Optiones (GROs) on Pb/zn Contaminated Sites

    Science.gov (United States)

    Friesl-Hanl, Wolfgang; Kidd, Petra; Siebielec, Grzegorz

    2017-04-01

    The GREENLAND-project brought together "best practice" examples of several field applied gentle remediation techniques (EUFP7-project "Gentle remediation of trace element-contaminated land - GREENLAND; www.greenland-project.eu) with 17 partners from 11 countries. Gentle remediation options (GRO) comprise environmentally friendly technologies that have little or no negative impact on the soil. The main technologies are • phytoextraction • in situ immobilization and • assisted phytostabilization. Mining and processing activities affecting many sites worldwide negatively. The huge amounts of moved and treated materials have led to considerable flows of wastes and emissions. Alongside the many advantages of processed ores to our society, adverse effects in nature and risks for the environment and human health are observed. Three stages of impact of Pb/Zn-ore-treatment on the environment are discussed here: (1) On sites where the ores are mined impacts are the result of crushing, grinding, concentrating activities, and where additionally parts of the installations remain after abandoning the mine, as well as by the massive amounts of remaining deposits or wastes (mine tailings). (2) On sites where smelting and processing takes place, depending on the process (Welz, Doerschel) different waste materials are deposited. The Welz process waste generally contains less Cd and Pb than the Doerschel process waste which additionally shows higher water- extractable metals. (3) On sites close to the emitting source metal contamination can be found in areas for housing, gardening, and agricultural use. Emissions consist mainly from oxides and sulfides (Zn, Cd), sulfates (Zn, Pb, and Cd), chlorides (Pb) and carbonates (Cd). All these wastes and emissions pose potential risks of dispersion of pollutants into the food chain due to erosion (wind, water), leaching and the transfer into feeding stuff and food crops. In-situ treatments have the potential for improving the situation

  11. Pixelated CdZnTe drift detectors

    DEFF Research Database (Denmark)

    Kuvvetli, Irfan; Budtz-Jørgensen, Carl

    2005-01-01

    A technique, the so-called Drift Strip Method (DSM), for improving the CdZnTe detector energy response to hard X-rays and gamma-rays was applied as a pixel geometry. First tests have confirmed that this detector type provides excellent energy resolution and imaging performance. We specifically...... report on the performance of 3 mm thick prototype CZT drift pixel detectors fabricated using material from eV-products. We discuss issues associated with detector module performance. Characterization results obtained from several prototype drift pixel detectors are presented. Results of position...

  12. The Influence of Pb and Zn Contaminated soil on the Germination ...

    African Journals Online (AJOL)

    This research work takes a look at the possible phytotoxic effects of Pb and Zn as Pb(NO3)2 and Zn(NO3)2 on Bambara nut (Vigna subterranea) planted in polluted. Lead and zinc are common environmental contaminant found in soils. Unlike Zn, Pb has no biological role, and is potentially toxic to microorganisms.

  13. Stable and metastable phases in reciprocal systems PbSe + Ag2I2 Ag2Se + PbI2 and PbSe + CdI2 = CdSe + PbI2

    International Nuclear Information System (INIS)

    Odin, I.N.; Grin'ko, V.V.; Kozlovskij, V.F.; Safronov, E.V.

    2005-01-01

    Mutual system PbSe + Ag 2 I 2 = Ag 2 Se + PbI 2 is investigated. It is shown that diagonal Ag 2 Se-PbI 2 is stable. Liquidus surface and isothermal section at 633 K of phase diagram of PbSe-Ag 2 Se-PbI 2 system are built. Transformations directing to crystallization metastable ternary compound forming in PbSe-PbI 2 system and metastable polytype modifications of lead iodide in PbSe-Ag 2 Se-PbI 2 system at 620-685 K are studied. By hardening from molten state (1150-1220 K) new interstitial metastable phases crystallizing in CdCl 2 structural type are obtained in PbSe-Ag 2 Se-PbI 2 and PbSe + CdI 2 = CdSe + PbI 2 systems [ru

  14. Relationships between T-cell-mediated immune response and Pb, Zn, Cu, Cd, and as concentrations in blood of nestling white storks (Ciconia ciconia) and black kites (Milvus migrans) from Doñana (southwestern Spain) after the Aznalcóllar toxic spill.

    Science.gov (United States)

    Baos, Raquel; Jovani, Roger; Forero, Manuela G; Tella, José L; Gómez, Gemma; Jiménez, Begoña; González, María J; Hiraldo, Fernando

    2006-04-01

    In the Aznalcóllar mining accident (April 1998), nearly six million cubic meters of toxic wastes were spilled in the surroundings of the Doñana National Park (southwestern Spain). The present study focused on the likely effects of metal pollution on the immune system of nestling white storks (Ciconia ciconia) and black kites (Milvus migrans) sampled in the nearby area. Using the phytohaemagglutinin skin test, we examined cell-mediated immune response (CMI) in relation to Pb, Zn, Cu, Cd, and As concentrations in blood of 281 nestling white storks and of 89 black kites. The former species was monitored along a four-year period (1999, 2001-2003), while black kites were sampled in 1999. Overall, average levels of heavy metals and As were relatively low when compared to those reported for birds in metal-polluted areas. Copper showed a negative effect on CMI in both species, although the relationship was significant only for white storks in 2002. We found no evidence that environmental exposure to Pb, Zn, As, and Cd had any effect on nestlings' CMI. Interannual consistency is revealed as an important factor, supporting the need of long-term studies when assessing the immunotoxic effects of metal exposure in the wild.

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

    Energy Technology Data Exchange (ETDEWEB)

    Nakayama, Shouta M.M.; Ikenaka, Yoshinori; Hamada, Kyohei [Laboratory of Toxicology, Department of Environmental Veterinary Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Kita 18, Nishi 9, Kita-ku, Sapporo 060-0818 (Japan); Muzandu, Kaampwe; Choongo, Kennedy [Department of Biomedical Studies, School of Veterinary Medicine, University of Zambia, P.O. Box 32379, Lusaka (Zambia); Teraoka, Hiroki; Mizuno, Naoharu [Department of Toxicology, School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu 069-8501 (Japan); Ishizuka, Mayumi, E-mail: ishizum@vetmed.hokudai.ac.j [Laboratory of Toxicology, Department of Environmental Veterinary Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Kita 18, Nishi 9, Kita-ku, Sapporo 060-0818 (Japan)

    2011-01-15

    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.

  16. Assessment of heavy metals (Cd and Pb) and micronutrients (Cu, Mn, and Zn) of paddy (Oryza sativa L.) field surface soil and water in a predominantly paddy-cultivated area at Puducherry (Pondicherry, India), and effects of the agricultural runoff on the elemental concentrations of a receiving rivulet.

    Science.gov (United States)

    Reddy, M Vikram; Satpathy, Deepmala; Dhiviya, K Shyamala

    2013-08-01

    The concentrations of toxic heavy metals-Cd and Pb and micronutrients-Cu, Mn, and Zn were assessed in the surface soil and water of three different stages of paddy (Oryza sativa L.) fields, the stage I-the first stage in the field soon after transplantation of the paddy seedlings, holding adequate amount of water on soil surface, stage II-the middle stage with paddy plants of stem of about 40 cm length, with sufficient amount of water on the soil surface, and stage III-the final stage with fully grown rice plants and very little amount of water in the field at Bahour, a predominantly paddy cultivating area in Puducherry located on the southeast Coast of India. Comparison of the heavy metal and micronutrient concentrations of the soil and water across the three stages of paddy field showed their concentrations were significantly higher in soil compared with that of water (p  Mn > Zn > Cu > Pb indicating concentration of Cd was maximum and Pb was minimum. The elemental concentrations in both soil and water across the three stages showed a ranking order of stage II > stage III > stage I. The runoff from the paddy fields has affected the elemental concentrations of the water and sediment of an adjacent receiving rivulet.

  17. Aqueous synthesis of glutathione-capped CdTe/CdS/ZnS and CdTe/CdSe/ZnS core/shell/shell nanocrystal heterostructures.

    Science.gov (United States)

    Samanta, Anirban; Deng, Zhengtao; Liu, Yan

    2012-05-29

    Here we demonstrate the aqueous synthesis of colloidal nanocrystal heterostructures consisting of the CdTe core encapsulated by CdS/ZnS or CdSe/ZnS shells using glutathione (GSH), a tripeptide, as the capping ligand. The inner CdTe/CdS and CdTe/CdSe heterostructures have type-I, quasi-type-II, or type-II band offsets depending on the core size and shell thickness, and the outer CdS/ZnS and CdSe/ZnS structures have type-I band offsets. The emission maxima of the assembled heterostructures were found to be dependent on the CdTe core size, with a wider range of spectral tunability observed for the smaller cores. Because of encapsulation effects, the formation of successive shells resulted in a considerable increase in the photoluminescence quantum yield; however, identifying optimal shell thicknesses was required to achieve the maximum quantum yield. Photoluminescence lifetime measurements revealed that the decrease in the quantum yield of thick-shell nanocrystals was caused by a substantial decrease in the radiative rate constant. By tuning the diameter of the core and the thickness of each shell, a broad range of high quantum yield (up to 45%) nanocrystal heterostructures with emission ranging from visible to NIR wavelengths (500-730 nm) were obtained. This versatile route to engineering the optical properties of nanocrystal heterostructures will provide new opportunities for applications in bioimaging and biolabeling.

  18. EVALUATION OF CONTAMINATION OF Zn-Pb INDUSTRY DEGRADED AREAS USING SPATIAL INFORMATION

    Directory of Open Access Journals (Sweden)

    Rafał Rozpondek

    2017-06-01

    Full Text Available The aim of this study was to evaluate soil contamination by heavy metals of selected area in the vicinity of the Zinc Smelter „Miasteczko Śląskie” (surface area: 147 ha, 1050 x 1400 meters for purpose of future reclamation, remediation and monitoring. The study used GIS. Network of 29 measuring points was planned, with particular emphasis on the area with the least amount of pure vegetation. In March 2016, two samples of soil were taken from the top layer of soil 0 - 20cm. Samples were analyzed in terms of pH, soil organic matter and total heavy metal content (As, Ba, Cd, Cu, Ni, Pb i Zn. Values of pH maintained in range of 3,7 - 7,9, organic matter 0,8 – 47,1% of solid content, As 0 – 32,5mg/kg, Ba 14 – 804mg/kg, Cd 0 – 19mg/kg, Cu 3 – 58mg/kg, Pb 22 – 1893mg/kg, Zn 36 – 1377mg/kg. In collected samples Ni was not detected. Spatial distributions of results were created. A significant data range and spatial differentiation was noted. On the base of the Regulation of the Minister of the Environment from September 1st, 2016 on the method of conducting the assessment of contamination of surface of the earth, areas contaminated with heavy metals were selected. Two different concentration limits were adopted: first in accordance with the actual method of land use (permissible values for group III - woodland and second relating to the possible undertaking of measures targeted at changing the land use (limit values for Group I - residential areas, recreational areas. On the basis of generated models, the area of the surface size that contains values higher than allowed in the quoted regulation were determined and calculated. In case of group III the values were exceeded for: Zn (surface area 0,9ha, Pb (46ha i Cd (27,8ha. For group I: As (0,3ha, Ba (10,2ha, Cd (53,9ha, Pb (120,8ha i Zn (20,2ha. The concentrations of Ni and Cu were lower than the limit value. The paper also determined zones with the highest contents of heavy metals. In

  19. Evaluation of physicochemical properties and distribution of Pb, Cd ...

    African Journals Online (AJOL)

    Evaluation of physicochemical properties and distribution of Pb, Cd, Cr and Ni in soils and growing plants around refuse dumpsites in Akure, Nigeria. ... Also there were corresponding increases in the organic carbon and cation exchange capacities of the soil indicating measurable levels of biodegradability of the wastes.

  20. Systems of Rb2I2-CdI2-PbI2 and Cs2I2-CdI2-PbI2

    International Nuclear Information System (INIS)

    Volchanskaya, V.V.; Il'yasov, I.I.

    1979-01-01

    The Rb 2 I 2 -CdI 2 -PbI 2 and Cs 2 I 2 -CdI 2 -PbI 2 triple systems have been studied, using the visual-polythermal method. The liquidus of the systems researched consists of the components and compounds crystallization fields: 2RbIxCdI 2 , 2RbIxRbI 2 , RbIxPbI 2 and 2CsIxCdI 2 , 4CsIxPbI 2 , CsIxPbI 2 , respectively. The crystallization fields converge in four non-variant points at 360, 280, 205 and 192 deg C in the Rb 2 I 2 -CdI 2 -PbI 2 system and at 375, 368, 208 and 190 deg C in the CsI 2 -CdI 2 -PbI 2 system

  1. Lime and Phosphate Amendment Can Significantly Reduce Uptake of Cd and Pb by Field-Grown Rice

    Directory of Open Access Journals (Sweden)

    Rongbo Xiao

    2017-03-01

    Full Text Available Agricultural soils are suffering from increasing heavy metal pollution, among which, paddy soil polluted by heavy metals is frequently reported and has elicited great public concern. In this study, we carried out field experiments on paddy soil around a Pb-Zn mine to study amelioration effects of four soil amendments on uptake of Cd and Pb by rice, and to make recommendations for paddy soil heavy metal remediation, particularly for combined pollution of Cd and Pb. The results showed that all the four treatments can significantly reduce the Cd and Pb content in the late rice grain compared with the early rice, among which, the combination amendment of lime and phosphate had the best remediation effects where rice grain Cd content was reduced by 85% and 61%, respectively, for the late rice and the early rice, and by 30% in the late rice grain for Pb. The high reduction effects under the Ca + P treatment might be attributed to increase of soil pH from 5.5 to 6.7. We also found that influence of the Ca + P treatment on rice production was insignificant, while the available Cd and Pb content in soil was reduced by 16.5% and 11.7%, respectively.

  2. Synthesis and characterization of (Cd,Zn)S buffer layer for Cu2ZnSnSe4 solar cells

    Science.gov (United States)

    Ben Messaoud, Khaled; Buffière, Marie; Brammertz, Guy; Lenaers, Nick; Boyen, Hans-Gerd; Sahayaraj, Sylvester; Meuris, Marc; Amlouk, Mosbah; Poortmans, Jef

    2017-07-01

    In order to improve the electrical performances of Cu2ZnSnSe4 (CZTSe) based solar cells, the standard CdS buffer layer was replaced by (Cd,Zn)S processed by chemical bath deposition. The morphology and composition of the (Cd,Zn)S thin films were studied as a function of [Zn]/([Zn]  +  [Cd]) ratio in the chemical bath (80, 85 and 90%). The CZTSe/(Cd,Zn)S solar cells with and without Cd partial electrolyte (Cd PE) treatment were compared to CZTSe/CdS reference devices using current-voltage and external quantum efficiency measurements. The (Cd,Zn)S thin films show a non-homogeneity of Zn distribution and phase formation, with a shift from Zn(O,OH) x to ZnS phase when increasing the deposition time and a decrease of the layers thicknesses when increasing the Zn concentration in chemical bath. A model for the growth of (Cd,Zn)S thin films is proposed. The resulting CZTSe/(Cd,Zn)S devices show an important reduction of the barrier at the hetero-interface, which is attributed to the lower density of O contamination in (Cd,Zn)S compared to CdS, inducing a lower density of deep p-type recombination centers. Despite the reduced compensation of the buffer layer, CZTSe/(Cd,Zn)S devices show a deterioration of the open circuit voltage and the fill factor with the increase of Zn content in (Cd,Zn)S. These electrical losses were avoided by Cd PE treatment prior to the deposition of (Cd,Zn)S.

  3. Reactions of the Zn Proteome with Cd2+and Other Xenobiotics: Trafficking and Toxicity.

    Science.gov (United States)

    Petering, David H

    2017-01-17

    Understanding the molecular basis of inorganic chemical toxicity has lagged behind the proliferation of detailed mechanisms that explain the biochemical toxicology of many organic xenobiotics. In this perspective, general barriers to explicating the bioinorganic chemistry of toxic metals are considered, followed by a detailed examination of these issues in relation to the toxicology of Cd 2+ . The hypothesis is evaluated that Cd 2+ damages cells by replacing Zn 2+ in key Zn proteins. An emerging methodology to assess the speciation of metals among cell proteins is described. Then, a more general hypothesis is suggested, namely, that the Zn proteome is also the toxicological target of other metals such as Pb 2+ as well as NO and reactive oxygen species. The latter may damage cells by altering the structure and function of Zn 2+ binding sites that include thiol ligands. In the process, labilized Zn 2+ may also perturb cell biochemistry. Lastly, reactions of metal chelating ligands with the Zn proteome, including formation of ligand-Zn protein adducts, provide other potential avenues of biochemical toxicity.

  4. Proper land use for heavy metal-polluted soil based on enzyme activity analysis around a Pb-Zn mine in Feng County, China.

    Science.gov (United States)

    Fang, Linchuan; Liu, Yuqing; Tian, Haixia; Chen, Hansong; Wang, Yunqiang; Huang, Min

    2017-12-01

    Enzymes in the soil are useful for assessing heavy metal soil pollution. We analyzed the activity of a number of enzymes, including urease, protease, catalase, and alkaline phosphatase, in three types of land (farmland, woodland, and grassland) to evaluate soil pollution by heavy metals (Pb, Zn, and Cd). Our results showed that the tested soil was polluted by a combination of Pb, Zn, and Cd, but the primary pollutant was Cd. An ecological dose analysis demonstrated that urease was the most sensitive enzyme to Pb and Cd in the farmland, and catalase and phosphatase were the most sensitive enzymes to Pb, Zn, and Cd in the woodland and grassland. The ecological risk of Cd (E Cd ) was the smallest in all three types of land, suggesting that Cd was the major metal inhibiting enzyme activity. Electrical conductivity (EC) was shown to be a negative regulator, while nitrogen, phosphorus, and clay contents were positive regulators of soil enzyme activity. The total enzyme index (TEI) inhibition rates in the woodland were 22.2 and 38.6% under moderate and heavy pollution, respectively, which were lower than those of the other two types of land. Therefore, woodlands might be the optimum land use choice in relieving heavy metal pollution. Taken together, this study identified the key metal pollutant inhibiting soil enzyme activity and suitable land use patterns around typical metal mine. These results provide possible improvement strategies to the phytomanagement of metal-contaminated land around world.

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

    International Nuclear Information System (INIS)

    Stadler, Adam Witold; Kolek, Andrzej; Zawislak, Zbigniew; Mleczko, Krzysztof; Jakubowska, Malgorzata; Kielbasinski, Konrad Rafal; Mlozniak, Anna

    2010-01-01

    Low-frequency noise spectroscopy has been used to examine noise properties of Pb/Cd-free RuO 2 - and CaRuO 3 -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 C bulk . 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 RuO 2 layers noise increases most likely due to larger grain size of RuO 2 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 C int . Pb/Cd-free RuO 2 -based resistive pastes form well-behaved interfaces with various Ag-based conductive pastes. In contrast, CaRuO 3 -based paste forms bad contacts with AgPd terminations because the density of TANSs increases in the interface area.

  6. Optical and structural characterization of CdS/ZnS and CdS:Cu(2+) /ZnS core-shell nanoparticles.

    Science.gov (United States)

    Murugadoss, G; Kumar, M Rajesh

    2014-09-01

    Core-shell CdS/ZnS (Zn 0.025-0.125 M) and CdS:Cu(2+) (1%)/ZnS nanoparticles were successfully synthesized using a chemical method. X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR TEM), photoluminescence (PL) and UV/Visible (UV/Vis) techniques were used to characterize the novel CdS/ZnS and CdS:Cu(2+) /ZnS core-shell nanoparticles. All absorption peaks of the synthesized samples were highly blue-shifted from the bulk CdS and ZnS. Very narrow and symmetric PL emission was observed in the yellow region for core-shell CdS/ZnS. Furthermore, the PL emission of CdS/ZnS was tuned into orange region by incorporate the Cu ion into the core CdS lattice. Copyright © 2013 John Wiley & Sons, Ltd.

  7. Thermal and electrical conductivities of Cd-Zn alloys

    International Nuclear Information System (INIS)

    Saatci, B; Ari, M; Guenduez, M; Meydaneri, F; Bozoklu, M; Durmus, S

    2006-01-01

    The composition and temperature dependences of the thermal and electrical conductivities of three different Cd-Zn alloys have been investigated in the temperature range of 300-650 K. Thermal conductivities of the Cd-Zn alloys have been determined by using the radial heat flow method. It has been found that the thermal conductivity decreases slightly with increasing temperature and the data of thermal conductivity are shifting together to the higher values with increasing Cd composition. In addition, the electrical measurements were determined by using a standard DC four-point probe technique. The resistivity increases linearly and the electrical conductivity decreases exponentially with increasing temperature. The resistivity and electrical conductivity are independent of composition of Cd and Zn. Also, the temperature coefficient of Cd-Zn alloys has been determined, which is independent of composition of Cd and Zn. Finally, Lorenz number has been calculated using the thermal and electrical conductivity values at 373 and 533 K. The results satisfy the Wiedemann-Franz (WF) relation at T 373 K), the WF relation could not hold and the phonon component contribution of thermal conductivity dominates the thermal conduction

  8. Electrical properties of MIS devices on CdZnTe/HgCdTe

    Science.gov (United States)

    Lee, Tae-Seok; Jeoung, Y. T.; Kim, Hyun Kyu; Kim, Jae Mook; Song, Jinhan; Ann, S. Y.; Lee, Ji Y.; Kim, Young Hun; Kim, Sun-Ung; Park, Mann-Jang; Lee, S. D.; Suh, Sang-Hee

    1998-10-01

    In this paper, we report the capacitance-voltage (C-V) properties of metal-insulator-semiconductor (MIS) devices on CdTe/HgCdTe by the metalorganic chemical vapor deposition (MOCVD) and CdZnTe/HgCdTe by thermal evaporation. In MOCVD, CdTe layers are directly grown on HgCdTe using the metal organic sources of DMCd and DiPTe. HgCdTe layers are converted to n-type and the carrier concentration, ND is low 1015 cm-3 after Hg-vacancy annealing at 260 degrees Celsius. In thermal evaporation, CdZnTe passivation layers were deposited on HgCdTe surfaces after the surfaces were etched with 0.5 - 2.0% bromine in methanol solution. To investigate the electrical properties of the MIS devices, the C-V measurement is conducted at 80 K and 1 MHz. C-V curve of MIS devices on CdTe/HgCdTe by MOCVD has shown nearly flat band condition and large hysteresis, which is inferred to result from many defects in CdTe layer induced during Hg-vacancy annealing process. A negative flat band voltage (VFB approximately equals -2 V) and a small hysteresis have been observed for MIS devices on CdZnTe/HgCdTe by thermal evaporation. It is inferred that the negative flat band voltage results from residual Te4+ on the surface after etching with bromine in methanol solution.

  9. A simple route to porous ZnO and ZnCdO nanowires.

    Science.gov (United States)

    Shan, C X; Liu, Z; Zhang, Z Z; Shen, D Z; Hark, S K

    2006-06-15

    Porous ZnO nanowires were obtained in an inexpensive and simple way by thermally oxidizing ZnSe nanowires in air. The morphologies of the precursor and resulted nanowires are almost identical. X-ray diffraction and energy-dispersive X-ray spectroscopy reveal that the zinc blende ZnSe nanowires were transformed into wurtzite ZnO nanowires after oxidation. Transmission electron microscope measurements indicate that the ZnO nanowires are polycrystalline and are composed of nanoparticles and nanopores. ZnCdO nanowires, which were seldom reported previously, have also been prepared in this way. Just like the ZnO nanowires, the ZnCdO nanowires also show the porous structure. Photoluminescence studies on both ZnO and ZnCdO nanowires show intense near-band edge emissions at room temperature. The transition from one kind of nanowires to another by simple thermal oxidization described in this paper may be applicable to some other compound semiconductors and may open a practical route to yield nanowires.

  10. Directional solidification of filamentary shapes of Pb--Cd and Pb--Sn eutectic alloys

    International Nuclear Information System (INIS)

    Dhindaw, B.K.; Verhoeven, J.D.; Spencer, C.R.; Gibson, E.D.

    1978-01-01

    Eutectic alloys of Pb--Cd and Pb--Sn were directionally solidified as thin filamentary strips contained in stainless steel and quartz capillaries. As the solidification rate increased the filament width, w, had to be reduced to maintain complete alignment of the lamellae clear across the filament. It was determined that in order to achieve complete alignment the ratio of filament width to lamellar spacing, w/lambda had to be less than about 30. Experiments were carried out at rates of 2-400 μm/s and at temperature gradients of 130 and 320 0 C/cm

  11. [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.

  12. Effect of ZnO and PbO/ZnO on structural and thermal properties of tellurite glasses

    International Nuclear Information System (INIS)

    Ramamoorthy, Raj Kumar; Bhatnagar, Anil K

    2015-01-01

    Highlights: • Structural units/linkages variation of TeO 2 -ZnO and TeO 2 -ZnO-PbO glasses was studied. • Structural arrangements of TeO 2 -ZnO glasses are rich in Te-O-Te network. • A mixture of Te-O-Te and Te-O-Pb networks is identified in TeO 2 -ZnO-PbO glasses. • Changes in thermal parameters T g and T o are correlated with the structural variations. • 15PbO and 20PbO samples of TeO 2 -ZnO-PbO glasses show large thermal stability. - Abstract: Two series of glasses, (100 − x)TeO 2 -xZnO (x = 20, 25, 30, 35) and 70TeO 2 -(30 − y)ZnO-yPbO (y = 5, 10, 15, 20), referred as TZ and TZP, respectively, were prepared by a melt quenching technique and characterized by X-ray diffraction (XRD), density, refractive index, Raman scattering and differential scanning calorimetry (DSC) to observe the changes in their properties as a function of ZnO and PbO/ZnO. Variations in individual structural units/linkages in these glasses are derived from the de-convoluted Raman spectra. The glass transition (T g ) and onset of crystallization (T o ) temperatures are determined from DSC isothermal scans. It is observed that the thermal stability (ΔT = T o − T g ) decreases for TZ glasses with increase in x, while it increases for TZP glasses with increase in y. Changes in thermal parameters of these glasses are correlated with the structural variation as a function of ZnO and PbO/ZnO ratio to determine the effect of substitution/addition of metal oxide, ZnO and PbO, to TeO 2 and TeO 2 -ZnO glasses

  13. One-step synthesis of PbSe-ZnSe composite thin film

    Directory of Open Access Journals (Sweden)

    Abe Seishi

    2011-01-01

    Full Text Available Abstract This study investigates the preparation of PbSe-ZnSe composite thin films by simultaneous hot-wall deposition (HWD from multiple resources. The XRD result reveals that the solubility limit of Pb in ZnSe is quite narrow, less than 1 mol%, with obvious phase-separation in the composite thin films. A nanoscale elemental mapping of the film containing 5 mol% PbSe indicates that isolated PbSe nanocrystals are dispersed in the ZnSe matrix. The optical absorption edge of the composite thin films shifts toward the low-photon-energy region as the PbSe content increases. The use of a phase-separating PbSe-ZnSe system and HWD techniques enables simple production of the composite package.

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

    International Nuclear Information System (INIS)

    Mita, Yoh; Kuronuma, Ryoichi; Inoue, Masanori; Sasaki, Shoichiro; Miyamoto, Yoshinobu

    2004-01-01

    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

  15. PbS/CdS-sensitized mesoscopic SnO2 solar cells for enhanced infrared light harnessing.

    Science.gov (United States)

    Hossain, Md Anower; Koh, Zhen Yu; Wang, Qing

    2012-05-28

    Metal oxide semiconductors with lower lying conduction band minimum and superior electron mobility are essential for efficient charge separation and collection in PbS-sensitized solar cells. In the present study, mesoscopic SnO(2) was investigated as an alternative photoanode to the commonly used TiO(2) and examined comprehensively in PbS-sensitized liquid junction solar cells. To exploit the capability of PbS in an optimized structure, cascaded nPbS/nCdS and alternate n(PbS/CdS) layers deposited by a successive ionic layer adsorption and reaction method were systematically scrutinized. It was observed that the surface of SnO(2) has greater affinity to the growth of PbS compared with TiO(2), giving rise to much enhanced light absorption. In addition, the deposition of a CdS buffer layer and a ZnS passivation layer before and after a PbS layer was found to be beneficial for efficient charge separation. Under optimized conditions, cascaded PbS/CdS-sensitized SnO(2) exhibited an unprecedented photocurrent density of 17.38 mA cm(-2) with pronounced infrared light harvesting extending beyond 1100 nm, and a power conversion efficiency of 2.23% under AM 1.5, 1 sun illumination. In comparison, TiO(2) cells fabricated under similar conditions showed much inferior performance owing to the less efficient light harnessing of long wavelength photons. We anticipate that the systematic study of PbS-sensitized solar cells utilizing different metal oxide semiconductors as electron transporters would provide useful insights and promote the development of semiconductor-sensitized mesoscopic solar cells employing panchromatic sensitizers.

  16. Kinetic Isotopic Fractionation of Cd and Zn During Condensation

    Science.gov (United States)

    Cloquet, C.; Carignan, J.; Libourel, G.

    2005-12-01

    The development of MC-ICPMS allowed to measure precisely isotopic compositions of transitional metals with a resolution generally better than +/- 0.15 per mil per atomic mass unit. The isotopic composition of such metals (Zn, Cd, Cu) varies in terrestrial and extra-terrestrial samples resulting most probably from phase transformations (solid-gas-solid) and/or biogenic fractionation. Up to now, very few experiments were conducted in order to document isotope fractionation during evaporation and condensation of metals. In this study, we report Cd and Zn elemental and isotopic variations measured in fly ashes collected from an urban waste combustor (UWC) equipped with various ash and flue gas filtration devices, including a heat transfer system. In the evacuation system, temperature drop from ca. 900 to 250 degree Celsius. This temperature range allows the evaporation and then condensation of Cd and Zn and probably fusion and oxido-reduction reactions. Indeed, the composition of combustion residues clearly indicates that most of the cadmium and part of the zinc were evacuated in the flue gases. Chemical analysis of the fly ashes collected along the thermal gradient suggest a massive condensation of semi-volatile elements such as Cd and Zn just above the heat transfer plate, which behave as a cold point in the evacuation system. As a first approximation, Cd and Zn contents are directly related to the amount metal condensates on more refractory particles. Leaching experiments on different fly ashes thermodynamic calculations confirmed the occurrence of soluble Cd and Zn salt condensates. The cadmium and Zn isotopic composition of bulk, leachate and residue samples provided variations as large as 1 per mil for delta 114Cd (114Cd/110Cd ratio) and up to 0.5 per mil for delta 66Zn (66Zn/64Zn ratio). Both Cd and Zn delta values are positively correlated to concentrations. According to the position of samples in the thermal gradient of the evacuation system, we suggest that

  17. Low temperature synthesis of ZnS and CdZnS shells on CdSe quantum dots

    Science.gov (United States)

    Zhu, Huiguang; Prakash, Arjun; Benoit, Denise N.; Jones, Christopher J.; Colvin, Vicki L.

    2010-06-01

    Methods for synthesizing quantum dots generally rely on very high temperatures to both nucleate and grow core and core-shell semiconductor nanocrystals. In this work, we generate highly monodisperse ZnS and CdZnS shells on CdSe semiconductor nanocrystals at temperatures as low as 65 °C by enhancing the precursor solubility. Relatively small amounts of trioctylphosphine and trioctylphosphine oxide have marked effects on the solubility of the metal salts used to form shells; their inclusion in the precursor solutions, which use thiourea as a sulfur source, can lead to homogeneous and fully dissolved solutions. Upon addition to suspensions of quantum dot cores, these precursors deposit as uniform shells; the lowest temperature for shell growth (65 °C) yields the thinnest shells (d forms thicker shells (d ~ 1-2 nm). The growth of the shell structures, average particle size, size distribution, and shape were examined using optical spectroscopy, transmission electron microscopy, x-ray diffraction, and transmittance small angle x-ray scattering. The photoluminescence quantum yield (QY) of the as-prepared CdSe/ZnS quantum dots ranged from 26% to 46% as compared to 10% for the CdSe cores. This method was further generalized to CdZnS shells by mixing cadmium and zinc acetate precursors. The CdSe/CdZnS nanocrystals have a thicker shell and higher QY (40% versus 36%) as compared to the CdSe/ZnS prepared under similar conditions. These low temperature methods for shell growth are readily amenable to scale-up and can provide a route for economical and less energy intensive production of quantum dots.

  18. Optical phonons in PbTe/CdTe multilayer heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Novikova, N. N.; Yakovlev, V. A. [Russian Academy of Sciences, Institute for Spectroscopy (Russian Federation); Kucherenko, I. V., E-mail: kucheren@sci.lebedev.ru [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation); Karczewski, G. [Polish Academy of Sciences, Institute of Physics (Poland); Aleshchenko, Yu. A.; Muratov, A. V.; Zavaritskaya, T. N.; Melnik, N. N. [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation)

    2015-05-15

    The infrared reflection spectra of PbTe/CdTe multilayer nanostructures grown by molecular-beam epitaxy are measured in the frequency range of 20–5000 cm{sup −1} at room temperature. The thicknesses and high-frequency dielectric constants of the PbTe and CdTe layers and the frequencies of the transverse optical (TO) phonons in these structures are determined from dispersion analysis of the spectra. It is found that the samples under study are characterized by two TO phonon frequencies, equal to 28 and 47 cm{sup −1}. The first frequency is close to that of TO phonons in bulk PbTe, and the second is assigned to the optical mode in structurally distorted interface layers. The Raman-scattering spectra upon excitation with the radiation of an Ar{sup +} laser at 514.5 nm are measured at room and liquid-nitrogen temperatures. The weak line at 106 cm{sup −1} observed in these spectra is attributed to longitudinal optical phonons in the interface layers.

  19. Preparation and characterization of ZnS:Fe/MX (M = Cd, Zn; X = S, Se) core-shell nanocrystals

    International Nuclear Information System (INIS)

    Li Lihua; Xie Ruishi; Gu Yongjun; Huang Jinliang; Zhu Jianguo

    2012-01-01

    ZnS:Fe/MX (M = Cd, Zn; X = S, Se) nanocrystals were synthesized by chemical precipitation method. Compared to ZnS:Fe nanocrystals, the diffraction peaks intensity of ZnS:Fe/ZnS nanocrystals reduced and the diffraction peaks of ZnS:Fe/ZnSe nanocrystals moved to lower angles. TEM photos show that ZnS:Fe and ZnS:Fe/ZnSe nanocrystals are spheroidal and the average particles size is about 2-4 nm. The selected-area electron diffraction pattern of ZnS:Fe/ZnSe nanocrystals shows the diffraction rings, indicating the ZnS:Fe/ZnSe nanocrystals have a polycrystalline structure. XPS shows that the divalent and trivalent of Fe ion are coexisted in ZnS:Fe nanocrystals. The emission peaks of ZnS:Fe nanocrystals were from S and Zn ions vacancy defects and surface defects for the range of 200-900 nm. The use of ZnS (CdS, ZnSe) as surface modifying reagent inhibited the luminescent intensity of ZnS:Fe nanocrystallines at 420 nm. The PL spectra of ZnS:Fe/CdS nanocrystals show a new peak at 554 nm.

  20. T-x-y diagrams for reciprocal systems PbX + CdI2 = CdX + PbI2 (X=S, Se, Te)

    International Nuclear Information System (INIS)

    Odin, I.N.

    2001-01-01

    The present research is undertaken in search of the new complex phases with interesting physical properties. The synthesized samples was analyzed by differential thermal, X-ray diffraction and microstructural methods. The diagonal cross-section CdTe - PbI 2 of the mutual PbTe + CdI 2 = CdTe + PbI 2 system is stable. The T-x phase diagram of the CdTe - PbI 2 system possess eutectic type, the coordinates of eutectic point is 657 ± 2 K, 15 ± 1 mol. % of CdTe. The lead iodide based solid solutions with the mixed structure and the CdTe based solid solutions take place in the equilibria. Solid CdTe dissolves 0.2 mol. % PbI 2 . The fields of the primary crystallization of the CdTe, Pb 1-x Cd x I 2 , PbTe based solid solutions are on the liquidus surface [ru

  1. ZnMgSe/ZnCdSe and ZnMgSe/ZnSeTe distributed Bragg reflectors grown by molecular beam epitaxy

    Science.gov (United States)

    Peiris, F. C.; Lee, S.; Bindley, U.; Furdyna, J. K.

    1999-07-01

    This article investigates distributed Bragg reflectors (DBRs) based on two wide-gap II-VI semiconductor alloy combinations: ZnMgSe/ZnCdSe and ZnMgSe/ZnSeTe. Prior to fabrication of the DBRs, a prism coupler technique was used to determine the indices of refraction n of the above ternary alloys of various compositions prepared by molecular beam epitaxy (MBE). Using these values of n, two DBR systems, Zn0.66Mg0.34Se/Zn0.74Cd0.20Se and Zn0.62Mg0.38Se/ZnSe0.56Te0.44, were fabricated, each with a relatively large difference in the indices of refraction between its layer materials. It was found that although a higher reflectivity could be achieved using the ZnMgSe/ZnSeTe combination (since it manifests a larger difference in their indices of refraction Δn=0.35), the number of periods which can be deposited in this DBR system is limited due to growth difficulties that arise when combining ZnMgSe and ZnSeTe. Therefore the ZnMgSe/ZnSeTe DBR system, which was restricted to just 10 periods, yielded a modest reflectivity of 85%. On the other hand, although Δn in the ZnMgSe/ZnCdSe DBR system is smaller (Δn=0.20), it poses fewer growth difficulties, making it possible to grow DBR stacks consisting of a large number of layers without compromising the crystal quality of the structure. By growing 20 periods of the ZnMgSe/ZnCdSe DBR system, we obtained a DBR with a reflectivity as high as 98%.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-12-15

    Graphical abstract: - Highlights: • We prepare two PbS/ZnO nanocomposite photocatalyts with different interface. • The PbS/ZnO interface plays important role in UV–vis–IR photodetection performance. • Disordered ZnS layer between PbS and ZnO considerably decreases photocurrent. • We reveal the origin of the interface effect on photodetection. - Abstract: 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(NO{sub 3}){sub 2} and Na{sub 2}S through changing the sequence of adding Pb(NO{sub 3}){sub 2} and Na{sub 2}S to the nano ZnO suspension: (A) first adding Pb(NO{sub 3}){sub 2} followed by adding Na{sub 2}S (denoted PbS/ZnO-A); (B) first adding Na{sub 2}S followed by adding Pb(NO{sub 3}){sub 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

  3. Investigation of the optoelectronic behavior of Pb-doped CdO nanostructures

    Science.gov (United States)

    Eskandari, Abdollah; Jamali-Sheini, Farid; Cheraghizade, Mohsen; Yousefi, Ramin

    2018-03-01

    Un- and lead (Pb)-doped cadmium oxide (CdO) semiconductor nanostructures were synthesized by a sonochemical method to study their physical properties. The obtained X-ray diffraction (XRD) patterns indicated cubic CdO crystalline structures for all samples and showed that the crystallite size of CdO increases with Pb addition. Scanning electron microscopy (SEM) images of the nanostructures illustrated agglomerated oak-like particles for the Pb-doped CdO nanostructures. Furthermore, optical studies suggested that the emission band gap energy of the CdO nanostructures lies in the range of 2.27-2.38 eV and crystalline defects increase by incorporation of Pb atoms in the CdO crystalline lattice. In addition, electrical experiments declared that the n-type electrical nature of the un- and Pb-doped CdO nanostructures and the minimum of Pb atoms lead to a high carrier concentration.

  4. Synthesis, structural, optical and photocatalytic properties of CdS/ZnS core/shell nanoparticles

    Science.gov (United States)

    Reddy, Ch. Venkata; Shim, Jaesool; Cho, Migyung

    2017-04-01

    CdS, ZnS and CdS/ZnS core/shell nanoparticles were successfully synthesized via two-step synthesis method. The as-prepared CdS, ZnS and CdS/ZnS core/shell nanoparticles were used to study the structural, morphological, and optical properties by PXRD, TEM, HRTEM, UV-vis spectroscopy, N2 adsorption-desorption, FT-IR, PL and Raman spectroscopy measurements. The XRD pattern confirms the crystal structure of the prepared ZnS, CdS, and CdS/ZnS core/shell nanoparticles. The crystallinity of the as-prepared samples is confirmed by PXRD, TEM and HRTEM analysis. The BET analysis showed that the CdS/ZnS core/shell nanoparticles had larger surface area and pore diameter than CdS and ZnS. The Raman and FT-IR spectra confirm the fundamental vibrational modes of CdS and ZnS respectively. Compared to pure CdS and ZnS, CdS/ZnS core/shell nanoparticles exhibited higher photocatalytic activity for the degradation of methyl orange (MO). The enhancement of photocatalytic activity in the CdS/ZnS core/shell nanoparticles is due to the interface actions between CdS and ZnS, which greatly reduces the recombination of photogenerated electrons-holes pair. The proposed mechanism for degradation of MO dye is discussed in detail.

  5. Structural and electrical measurements of CdZnSe composite

    Indian Academy of Sciences (India)

    Unknown

    cation for novel optoelectronic devices such as light emitting diodes, photoelectrodes, blue green laser etc. (Samarth et al 1990) in the visible region of electromag- netic radiation (Gupta et al 1995b). Further, research of optical and electrical properties of CdZnSe system, forms a basis of active region of laser and LED.

  6. [Effects of soil properties on the stabilization process of cadmium in Cd alone and Cd-Pb contaminated soils].

    Science.gov (United States)

    Wu, Man; Xu, Ming-Gang; Zhang, Wen-Ju; Wu, Hai-Wen

    2012-07-01

    In order to clarify the effects of soil properties on the stabilization process of the cadmium (Cd) added, 11 different soils were collected and incubated under a moisture content of 65%-70% at 25 degrees C. The changes of available Cd contents with incubation time (in 360 days) in Cd and Cd-Pb contaminated treatments were determined. The stabilization process was simulated using dynamic equations. The results showed that after 1.0 mg x kg(-1) Cd or 500 mg x kg(-1) Pb + 1.0 mg x kg(-1) Cd were added into the soil, the available Cd content decreased rapidly during the first 15 days, and then the decreasing rate slowed down, with an equilibrium content reached after 60 days' incubation. In Cd-Pb contaminated soils, the presence of Pb increased the content of available Cd. The stabilization process of Cd could be well described by the second-order equation and the first order exponential decay; meanwhile, dynamic parameters including equilibrium content and stabilization velocity were used to characterize the stabilization process of Cd. These two key dynamic parameters were significantly affected by soil properties. Correlation analysis and stepwise regression suggested that high pH and high cation exchange capacity (CEC) significantly retarded the availability of Cd. High pH had the paramount effect on the equilibrium content. The stabilization velocity of Cd was influenced by the soil texture. It took shorter time for Cd to get stabilized in sandy soil than in the clay.

  7. 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.

  8. CHEMICAL DETERMINATION OF HEAVY METALS IN PB AND ZN CONCENTRATES OF TREPÇA (KOSOVO AND CORRELATIONS COEFFI CIENTS STUDY BETWEEN CHEMICAL DATA

    Directory of Open Access Journals (Sweden)

    Fatbardh Gashi

    2017-03-01

    Full Text Available Kosovo ore deposits are located in the Trepça belt which extends for over 80 km. The concentrate produced by the flotation process of the Trepça metallurgical corporation contains a considerable quantity of valuable metals, such as Pb, Zn, Fe and minor accompanying metals such as Cd, Cu, As, Sb, Bi, Ag, Au, etc. The subject of this work was to assess the concentration of major and minor metals in lead and zinc concentrates of Trepça and to study the correlation coefficients between metals. Chemical determination of concentrates was performed by using atomic absorption spectroscopy (AAS. In the content on lead concentrate samples, the following were found: Pb>Fe>Zn> Ag> As>Sb>Cd. In the content of zinc concentrate, the following were found: Zn>Fe>Pb>Ag>As>Cd. The program “Statistica ver. 6.0” has been used for calculations of basic statistical parameters, relationships between data and cluster analysis of R-mode. R-mode cluster analysis on lead concentrate samples showed that Pb has the closest linkages with Fe and they form one branch of the dendogram. On the zinc concentrate samples, Zn has the closest linkages with Fe and they form one branch of the dendogram.

  9. 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.

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

    NARCIS (Netherlands)

    Arnetoli, M.; Vooijs, H.; Gonelli, C.; Gabbrielli, R.; Verkleij, J.A.C.; Schat, H.

    2008-01-01

    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

  11. Influence of Zn additions on the interfacial reaction and microstructure of Sn37Pb/Cu solder joints

    Science.gov (United States)

    Qiu, Yu; Hu, Xiaowu; Li, Yulong; Jiang, Xiongxin

    2017-10-01

    The effects of Zn (5 and 10 wt%) additions into Sn37Pb solder and isothermal solid state aging on the interfacial reactions between Sn37Pb- xZn solders and Cu substrates were investigated in this study. It was found that the addition of Zn changed the types and morphologies of interfacial IMC layers during reflowing and thereafter under aging condition. During reflowing, the planar-type Cu5Zn8 compound was the interfacial IMC for Sn37Pb- xZn (5 and 10 wt%) solder, while the scallop-type Cu6Sn5 was the interfacial IMC for Sn37Pb solder. After aging, the final interfacial structure for Sn37Pb-5Zn solder was solder/Cu5Zn8/Cu6(Sn,Zn)5/Cu, while solder/Cu6Sn5/Cu3Sn/Cu for Sn37Pb solder and solder/Cu5Zn8/Cu for Sn37Pb-10Zn solder, respectively. The Kirkendall voids disappeared with Zn addition into Sn37Pb solder. For the Sn37Pb-5Zn/Cu solder joint, the thickness of Cu6(Sn,Zn)5 layer increased, while the thickness of Cu5Zn8 layer decreased with aging time extended to 360 h due to the decomposition of the Cu5Zn8 IMC layer by diffusing Cu and Zn atoms into nether IMC layer, combining Sn atoms diffused from solder matrix to form Cu6(Sn,Zn)5 IMCs. Furthermore, the growth of Cu6Sn5 and Cu3Sn layers for Sn37Pb/Cu solder joint and the total IMC layer at the interface of Sn37Pb- xZn ( x = 0, 5, and 10 wt%) solder with Cu substrate followed the diffusion control mechanism. Compared to the Sn37Pb-5Zn/Cu solder joint, higher Zn concentration depressed the growth of Cu5Zn8 layer for Sn37Pb-10Zn solder. In the end, refining effect on IMC grains was found by the addition of Zn into Sn37Pb solder and the 10 wt% Zn-doping significantly refined the interfacial IMC grains.

  12. Tolerance of Portulaca grandiflora to individual and combined application of Ni, Pb and Zn.

    Science.gov (United States)

    Mihailovic, N; Andrejić, G; Dželetović, Ž

    2015-01-01

    In the present study, metal accumulation capacity and tolerance of Portulaca grandiflora were investigated. Plants were grown under greenhouse conditions in pots on soil amended with Ni, Pb and Zn to the final concentration of 2 mmol kg(-1) for each metal. Results show considerable accumulating capacity and translocation of Ni and Zn, as well as significant accumulation of Pb in roots. A slight decrease of biomass with Zn and of chlorophyll content with Zn and Ni were observed, as well as an increase of proline content with each of the metals. Combinations of metals revealed mutual interference affecting both the uptake and translocation of the metals and their impact on physiological parameters. Results suggest that Portulaca grandiflora, although not a hyperaccumulator, shows a good tolerance and accumulation capacity for Ni, Pb and Zn, but, for the purposes of remediation, interference of the metals must be taken into account.

  13. Quantifying the signature of the industrial revolution from Pb and Cd isotopes in the Susquehanna Shale Hills Critical Zone Observatory

    Science.gov (United States)

    Ma, L.; Herndon, E.; Jin, L.; Sanchez, D.; Brantley, S. L.

    2013-12-01

    Anthropogenic forcings have dominated metal cycling in many environments. During the period of the industrial revolution, mining and smelting of ores and combustion of fossil fuels released non-negligible amounts of potentially toxic metals such as Pb, Cd, Mn, and Zn into the environment. The extent and fate of these metal depositions in soils during that period however, have not been adequately evaluated. Here, we combine Pb isotopes with Cd isotopes to trace the sources of metal pollutants in a small temperate watershed (Shale Hills) in Pennsylvania. Previous work has shown that Mn additions to soils in central PA was caused by early iron production, as well as coal burning and steel making upwind. Comparison of the Pb and Cd concentrations in the bedrock and soils from this watershed show that Pb and Cd in soils at Shale Hills are best characterized by addition profiles, consistent with atmospheric additions. Three soil profiles at Shale Hills on the same hillslope have very similar anthropogenic Pb inventories. Pb isotope results further reveal that the extensive use of local coals during iron production in early 19th century in Pennsylvania is most likely the anthropogenic Pb source for the surface soils at Shale Hills. Pb concentrations and isotope ratios were used to calculate mass balance and diffusive transport models in soil profiles. The model results further reveal that during the 1850s to 1920s, coal burning in local iron blasting furnaces significantly increased the Pb deposition rates to 8-14 μg cm-2 yr-1, even more than modern Pb deposition rates derived from the use of leaded gasoline in the 1940s to 1980s. Furthermore, Cd has a low boiling point (~760 °C) and easily evaporates and condenses. The evaporation and condensation processes could generate systematic mass-dependent isotope fractionation between Cd in coal burning products and the naturally occurring Cd in the sulfide minerals of coals. This fractionation indicates that Cd isotopes can

  14. On the interplay of point defects and Cd in non-polar ZnCdO films

    International Nuclear Information System (INIS)

    Zubiaga, A.; Reurings, F.; Tuomisto, F.; Plazaola, F.; García, J. A.; Kuznetsov, A. Yu.; Egger, W.; Zúñiga-Pérez, J.; Muñoz-Sanjosé, V.

    2013-01-01

    Non-polar ZnCdO films, grown over m- and r-sapphire with a Cd concentration ranging between 0.8% and 5%, have been studied by means of slow positron annihilation spectroscopy (PAS) combined with chemical depth profiling by secondary ion mass spectroscopy and Rutherford back-scattering. Vacancy clusters and Zn vacancies with concentrations up to 10 17 cm −3 and 10 18 cm −3 , respectively, have been measured inside the films. Secondary ion mass spectroscopy results show that most Cd stays inside the ZnCdO film but the diffused atoms can penetrate up to 1.3 μm inside the ZnO buffer. PAS results give an insight to the structure of the meta-stable ZnCdO above the thermodynamical solubility limit of 2%. A correlation between the concentration of vacancy clusters and Cd has been measured. The concentration of Zn vacancies is one order of magnitude larger than in as-grown non-polar ZnO films and the vacancy cluster are, at least partly, created by the aggregation of smaller Zn vacancy related defects. The Zn vacancy related defects and the vacancy clusters accumulate around the Cd atoms as a way to release the strain induced by the substitutional Cd Zn in the ZnO crystal.

  15. On the interplay of point defects and Cd in non-polar ZnCdO films

    Energy Technology Data Exchange (ETDEWEB)

    Zubiaga, A.; Reurings, F.; Tuomisto, F. [Department of Applied Physics, Aalto University, P.O. Box 11100, 00076 Aalto, Espoo (Finland); Plazaola, F. [Elektrizitatea eta Elektronika/Fisika Aplikatua II Sailak, Euskal Herriko Unibertsitatea, Posta Kutxatila 644, 48080 Bilbao (Spain); Garcia, J. A. [Fisika Aplikatua II Saila, Euskal Herriko Unibertsitatea, Posta Kutxatila 644, 48080 Bilbao (Spain); Kuznetsov, A. Yu. [Department of Physics, University of Oslo, P.O. Box 1048 Blindern, NO-0316 Oslo (Norway); Egger, W. [Inst. fuer Angewandte Physik und Messtechnik, Univ. der Bundeswehr Muenchen, 87755 Neubiberg (Germany); Zuniga-Perez, J. [CRHEA CNRS, F-06560 Valbonne (France); Munoz-Sanjose, V. [Dept. de Fisica Aplicada i Electromagnetisme, c/ Doctor Moliner 50, E-46100 Burjassot (Valencia) (Spain)

    2013-01-14

    Non-polar ZnCdO films, grown over m- and r-sapphire with a Cd concentration ranging between 0.8% and 5%, have been studied by means of slow positron annihilation spectroscopy (PAS) combined with chemical depth profiling by secondary ion mass spectroscopy and Rutherford back-scattering. Vacancy clusters and Zn vacancies with concentrations up to 10{sup 17} cm{sup -3} and 10{sup 18} cm{sup -3}, respectively, have been measured inside the films. Secondary ion mass spectroscopy results show that most Cd stays inside the ZnCdO film but the diffused atoms can penetrate up to 1.3 {mu}m inside the ZnO buffer. PAS results give an insight to the structure of the meta-stable ZnCdO above the thermodynamical solubility limit of 2%. A correlation between the concentration of vacancy clusters and Cd has been measured. The concentration of Zn vacancies is one order of magnitude larger than in as-grown non-polar ZnO films and the vacancy cluster are, at least partly, created by the aggregation of smaller Zn vacancy related defects. The Zn vacancy related defects and the vacancy clusters accumulate around the Cd atoms as a way to release the strain induced by the substitutional Cd{sub Zn} in the ZnO crystal.

  16. Critical elements in sediment-hosted deposits (clastic-dominated Zn-Pb-Ag, Mississippi Valley-type Zn-Pb, sedimentary rock-hosted Stratiform Cu, and carbonate-hosted Polymetallic Deposits): A review: Chapter 12

    Science.gov (United States)

    Marsh, Erin; Hitzman, Murray W.; Leach, David L.

    2016-01-01

    Some sediment-hosted base metal deposits, specifically the clastic-dominated (CD) Zn-Pb deposits, carbonate-hosted Mississippi Valley-type (MVT) deposits, sedimentary-rock hosted stratiform copper deposits, and carbonate-hosted polymetallic (“Kipushi type”) deposits, are or have been important sources of critical elements including Co, Ga, Ge, and Re. The generally poor data concerning trace element concentrations in these types of sediment-hosted ores suggest that there may be economically important concentrations of critical elements yet to be recognized.

  17. Volatility and partitioning of Cd and Pb during sewage sludge thermal conversion.

    Science.gov (United States)

    Zhang, Yi-Fan; Zhang, Shou-Yu; Mao, Qing; Li, Hao; Wang, Cai-Wei; Jiang, Feng-Hao; Lyu, Jun-Fu

    2018-02-09

    In this paper, the thermal characteristics of sewage sludge and the transformation behavior of Pb and Cd during the thermal conversion process were addressed. The incineration process and pyrolysis process of the sewage sludge were investigated by thermogravimetric analysis. The results indicated that the thermal conversion process of the sewage sludge could be divided into three stages and the presence of oxygen could accelerate the decomposition of the sewage sludge. Furthermore, the effects of thermal conditions on the concentration ratio of Cd and Pb and their species partitioning in the residual char and ash were investigated. For the pyrolysis process, the maximum concentration ratio of Cd reached 41.64% at 500 °C and the lowest one 2.92% at 700 °C. Contrary, the concentration ratio of Pb remained above 93% as the temperature increased. Thus, the suitable temperature for the sewage sludge pyrolysis was below 500 °C. For the incineration process, the incineration temperature had great influence on the concentration ratio of Cd and Pb. When the incineration temperature increased from 700 °C to 900 °C, the concentration ratio of Cd decreased drastically from 99.32% to 10.96%. The maximum concentration ratio for Pb (95.31%) was reached at 800 °C. Besides, the lowest concentration ratio of Cd and Pb were obtained at a residence time of 30 min. The partitioning analyses of the Cd and Pb contained in the ash showed that the residence time had little effect on the partitioning of Cd and Pb, and the residual fractions of Cd and Pb were both above 90%. It was concluded that Cd and Pb were properly stabilized in the ash. Thus, Cd and Pb in the ash were difficult to be released into the environment and to cause secondary pollution. Copyright © 2018. Published by Elsevier Ltd.

  18. The giant Upper Yangtze Pb-Zn province in SW China: Reviews, new advances and a new genetic model

    Science.gov (United States)

    Zhou, Jia-Xi; Xiang, Zhen-Zhong; Zhou, Mei-Fu; Feng, Yue-Xing; Luo, Kai; Huang, Zhi-Long; Wu, Tao

    2018-04-01

    western Yangtze Block. The change of tectonic regimes from extension to compression after eruption of basalts of the ELIP, and then to extension during Early Mesozoic, facilitated extraction, migration, and excretion of ore-forming metals and associated fluids. Mixing of fluids and reduction geochemical barrier activated TSR, causing cyclical carbonate dissolution, CO2 degassing and recrystallization (namely carbonate buffer). All these processes triggered continuous precipitation of huge amounts of hydrothermal minerals. Underplating and eruption of ELIP basalts provided heat flow, fluids and volatiles, whereas the basalts acted as an impermeable and protective layer, and even as ore-hosting rocks. These Pb-Zn deposits have spatial and genetic association with igneous activities of the ELIP, and are characterized by high ore grades (>10 wt% Pb + Zn), high concentrations of associated metals (e.g. Cu, Ag, Ge, and Cd), and medium-low temperatures (usually zones of passive margin tectonic settings.

  19. Metastable phases freezing from melts of reciprocal systems PbX + CdI2=CdX + PbI2 (X=S, Se, Te)

    International Nuclear Information System (INIS)

    Odin, I.N.; Chukichev, M.V.

    2001-01-01

    The transformations in the mutual PbX + CdI 2 =CdX + PbI 2 (X=S, Se, Te) systems leading to the crystallization of metastable polytypical modifications of lead iodide in metastable ternary compounds are studied for the first time. Microstructural and X-ray diffraction analyses were conducted. Their phase diagrams were constructed. The luminescence properties of the stable and metastable modifications of the lead iodide and the metastable compound Pb 4 SeI 6 were investigated. The lines 504 and 512 nm are noted in the 2H-PbI 2 cathodoluminescence spectra. The close lines - 508 and 516 nm provide for the 6R-PbI 2 modification. The metastable compound Pb 4 SeI 6 is characterized by the 769 and 868 nm lines [ru

  20. Macronutrient status and speciation of cu, fe, zn and pb in soil ...

    African Journals Online (AJOL)

    Soils at 100m away from the discharge point were regarded as normal or uncontaminated soils, while different extractants were used to determine the levels of Fe, Cu, Zn and Pb. The results showed enrichment of the soils in P, N, Ca, Mg, Na, K due to the application of the POME. Copper, Iron and Pb were predominant in ...

  1. Lead Isotopic Compositions of Selected Coals, Pb/Zn Ores and Fuels in China and the Application for Source Tracing.

    Science.gov (United States)

    Bi, Xiang-Yang; Li, Zhong-Gen; Wang, Shu-Xiao; Zhang, Lei; Xu, Rui; Liu, Jin-Ling; Yang, Hong-Mei; Guo, Ming-Zhi

    2017-11-21

    Lead (Pb) pollution emission from China is becoming a potential worldwide threat. Pb isotopic composition analysis is a useful tool to accurately trace the Pb sources of aerosols in atmosphere. In this study, a comprehensive data set of Pb isotopes for coals, Pb/Zn ores, and fuels from China was presented. The ratios of 206 Pb/ 207 Pb and 208 Pb/ 206 Pb in the coals were in the range of 1.114-1.383 and 1.791-2.317, similar to those from Europe, Oceania, and South Asia, but different from those from America (p fuels from in coals. Urban aerosols demonstrated similar Pb isotopic compositions to coals, Pb/Zn ores, and fuels in China. After removing the leaded gasoline, the Pb in aerosols is more radiogenic, supporting the heavy contribution of coal combustion to the atmospheric Pb pollution.

  2. Influence of amendments and aided phytostabilization on metal availability and mobility in Pb/Zn mine tailings.

    Science.gov (United States)

    Lee, Sang-Hwan; Ji, WonHyun; Lee, Won-Seok; Koo, Namin; Koh, Il Ha; Kim, Min-Suk; Park, Jeong-Sik

    2014-06-15

    A greenhouse experiment was conducted to evaluate the effect of four different amendments, bone mill, bottom ash, furnace slag, and red mud, as immobilizing agents and the plant species Miscanthus sinensis and Pteridium aquilinum in aided phytostabilization of Pb/Zn mine tailings. The effects of amendments and plants on the availability and mobility of heavy metals were evaluated using single extraction, sequential extraction, pore-water analysis, and determination of heavy metal concentrations in plants. The application of Fe-rich amendments significantly reduced the amount of soluble and extractable heavy metals in the tailings (p aquilinum treatment was the most effective at decreasing bioaccessible Pb, reducing it to 34% of the total Pb. Compared to control, water soluble Cd, Cu, Pb, and Zn were reduced by 99, 99, 98, and 99%, respectively, in the red mud and P. aquilinum tailings. M. sinensis accumulated heavy metals mainly in the root, and had lower translocation factors compared with P. aquilinum. The results of this study suggest that M. sinensis can be used in aided phytostabilization for these types of mine tailings and Fe-rich amendments are effective for the in situ immobilization of metals. Copyright © 2014 Elsevier Ltd. All rights reserved.

  3. Thermally induced atomic reconstruction of PbSe/CdSe core/shell quantum dots into PbSe/CdSe bi-hemisphere hetero-nanocrystals

    NARCIS (Netherlands)

    Grodzinska, D.; Pietra, F; van Huis, M.A.; Vanmaekelbergh, D.A.M.; de Mello Donega, C.

    2011-01-01

    The properties of hetero-nanocrystals (HNCs) depend strongly on the mutual arrangement of the nanoscale components. In this work we have investigated the structural and morphological evolution of colloidal PbSe/CdSe core/shell quantum dots upon annealing under vacuum. Prior to annealing the PbSe

  4. Investigation of effect of Ag(1), Cd(2) and Zn(2) on chemical nickel plating

    International Nuclear Information System (INIS)

    Lunyatskas, A.M.; Tarozajte, R.K.; Gyanutene, I.K.; Lyaukonis, Yu.Yu.

    1978-01-01

    Investigated is the effect of Ag(1), Cd(2) and Zn(2) on chemical nickel plating using hypophosphite aimed to get corresponding alloys from alkali solutions. The H 2 formed volume and potential of coating have been measured while nickel plating. It is possible to have plating of Ni-P-Ag, Ni-P-Zn, Ni-P-Cd, Ni-P-Zn-Cd content coatings in alkali solutions using hypophosphite Ni-P-Zh and Ni-P-Zn-Cd coatings have corrosion resistance and unporousness. Cd and Zn inclusion in Ni-P coating is supposed to have both chemical and electrochemical origin

  5. 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.

  6. Bioaccessibility of Ba, Cu, Pb, and Zn in urban garden and orchard soils

    International Nuclear Information System (INIS)

    Cai, Meifang; McBride, Murray B.; Li, Kaiming

    2016-01-01

    Exposure of young children to toxic metals in urban environments is largely due to soil and dust ingestion. Soil particle size distribution and concentrations of toxic metals in different particle sizes are important risk factors in addition to bioaccessibility of these metals in the particles. Analysis of particle size distribution and metals concentrations for 13 soils, 12 sampled from urban gardens and 1 from orchard found that fine particles (<105 μm) comprised from 22 to 66% by weight of the tested soils, with Ba, Cu, Pb and Zn generally at higher concentrations in the finer particles. However, metal bioaccessibility was generally lower in finer particles, a trend most pronounced for Ba and Pb. Gastric was higher than gastrointestinal bioaccessibility for all metals except Cu. The lower bioaccessibility of Pb in urban garden soils compared to orchard soil is attributable to the higher organic matter content of the garden soils. - Highlights: • The bioaccessibility of metals in urban garden and orchard soils was measured. • Ba, Cu, Pb, Zn were concentrated in fine particles of the soils. • Bioaccessibilities of Ba and Pb were generally lower in fine particles of soils. • Pb bioaccessibility was generally lower in soils with higher organic matter content. • Pb bioaccessibility was lower in urban garden soils than in an orchard soil. - Pb and other trace metals (Ba, Cu, Zn) were concentrated in fine particles of urban and orchard soils, but the bioaccessibility of Ba and Pb was generally lower in finer particles.

  7. Aqueous synthesis of CdTe/CdS/ZnS quantum dots and their optical and chemical properties.

    Science.gov (United States)

    Li, Zhong; Dong, Chaoqing; Tang, Lichuan; Zhu, Xin; Chen, Hongjin; Ren, Jicun

    2011-01-01

    In this paper, we described a strategy for synthesis of thiol-coated CdTe/CdS/ZnS (core-shell-shell) quantum dots (QDs) via aqueous synthesis approach. The synthesis conditions were systematically optimized, which included the size of CdTe core, the refluxing time and the number of monolayers and the ligands, and then the chemical and optical properties of the as-prepared products were investigated. We found that the mercaptopropionic acid (MPA)-coated CdTe/CdS/ZnS QDs presented highly photoluminescent quantum yields (PL QYs), good photostability and chemical stability, good salt tolerance and pH tolerance and favorable biocompatibility. The characterization of high-resolution transmission electron microscopy (HRTEM), X-ray powder diffraction (XRD) and fluorescence correlation spectroscopy (FCS) showed that the CdTe/CdS/ZnS QDs had good monodispersity and crystal structure. The fluorescence life time spectra demonstrated that CdTe/CdS/ZnS QDs had a longer lifetime in contrast to fluorescent dyes and CdTe QDs. Furthermore, the MPA-stabilized CdTe/CdS/ZnS QDs were applied for the imaging of cells. Compared with current synthesis methods, our synthesis approach was reproducible and simple, and the reaction conditions were mild. More importantly, our method was cost-effective, and was very suitable for large-scale synthesis of CdTe/CdS/ZnS QDs for future applications. Copyright © 2010 John Wiley & Sons, Ltd.

  8. EDTA-assisted leaching of Pb and Cd from contaminated soil.

    Science.gov (United States)

    Qiao, Jiangbo; Sun, Huimin; Luo, Xiuhua; Zhang, Wang; Mathews, Shiny; Yin, Xianqiang

    2017-01-01

    Lead (Pb) and cadmium (Cd) contamination of soil and its harmful effects on human and environmental health have been one concern. In this study, batch and column leaching experiments were conducted to investigate the effects of two EDTA-assisted leaching methods, continuous and intermittent (dry-wet alternate), on the removal of Pb and Cd from contaminated soil. Total content and fractions of Pb and Cd at every 1 cm soil column depth were analyzed before and after the leaching. The results indicated that continuous leaching removed 75.43% of Pb (19.370 mg) and 53.21% of Cd (6.168 mg) and intermittent leaching removed 78.08% of Pb (20.051 mg) and 57.37% of Cd (6.650 mg), which showed intermittent leaching removed more Pb and Cd, but didn't differ significantly (P > 0.05) compared to the continuous leaching. In both leaching methods, total Pb and Cd content in all soil depths reduced after leaching. The two leaching methods made no significant differences in Pb and Cd distributions at different depths of the soil column. Copyright © 2016 Elsevier Ltd. All rights reserved.

  9. Remediation of Biological Organic Fertilizer and Biochar in Paddy Soil Contaminated by Cd and Pb

    Directory of Open Access Journals (Sweden)

    MA Tie-zheng

    2015-02-01

    Full Text Available The effect of application of biological organic fertilizer and biochar on the immobilized remediation of paddy soil contaminated by Cd and Pb was studied under the field experiment. The results showed that biological organic fertilizer and biochar increased the soil pH and soil nutrient contents, and reduced the soil available Cd and Pb concentrations significantly. The soil pH had significantly negative correla-tion with the soil available Cd and Pb contents. The application of biological organic fertilizer and biochar decreased Cd and Pb concentration in all parts of the rice plant, with Cd concentration in brown rice decrease by 22.00% and 18.34% and Pb decease in brown rice by 33.46% and 12.31%. The concentration of Cd and Pb in brown rice had significant positive correlation with the soil available Cd and Pb concentra-tions. It was observed that both biological organic fertilizer and biochar had a positive effect on the remediation of paddy soil contaminated by Cd and Pb.

  10. Colloidal atomic layer deposition growth of PbS/CdS core/shell quantum dots.

    Science.gov (United States)

    Nasilowski, Michel; Nienhaus, Lea; Bertram, Sophie N; Bawendi, Moungi G

    2017-01-10

    Traditionally, PbS/CdS quantum dots (QDs) have been synthesized via a cation exchange method, making fine control over shell growth challenging. We show here that colloidal atomic layer deposition (c-ALD) allows for the sequential growth of single monolayers of the shell, thus creating a 'true' CdS shell on PbS QDs.

  11. Colloidal PbSe/CdSe Heteronanocrystals. Atomic configuration, electronic structure and optical properties

    NARCIS (Netherlands)

    Grodzinska, D.

    2012-01-01

    This thesis focuses on the structural characterization and the opto-electronic properties of PbSe/CdSe core/shell QDs and on the structural and morphological evolution of PbSe/CdSe core/shell QDs upon thermal annealing under vacuum.

  12. Behaviours of MeCl 2 (Me: Pb and Cd) during thermal treatment of ...

    African Journals Online (AJOL)

    This paper reports the emission behaviours of Pb and Cd during heat treatment of their chloride salts with kaolin-lime and kaolin-lime-silica mixtures. The leaching behaviours of Pb and Cd from the heattreated products are also assessed. The results showed that the addition of lime into kaolin increased the emitted amounts ...

  13. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Spencer, C. R.

    1977-09-01

    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.

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

    International Nuclear Information System (INIS)

    Spencer, C.R.

    1977-09-01

    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

  16. Synthesis and characterization of PbO-CdO nanocomposite and its effect on (Bi,Pb)-2223 superconductor

    Energy Technology Data Exchange (ETDEWEB)

    Yahya, Nabil A.A. [Thamar University, Physics Department, Faculty of Education, Thamar (Yemen); Al-Gaashani, R. [Thamar University, Physics Department, Faculty of Education, Thamar (Yemen); Qatar Environment and Energy Research Institute (QEERI), Hamad Bin Khalifa University (HBKU), Doha (Qatar); Abd-Shukor, R. [Universiti Kebangsaan Malaysia, School of Applied Physics, Bangi, Selangor (Malaysia)

    2017-03-15

    A PbO-CdO nanocomposite-added Bi{sub 1.6}Pb{sub 0.4}Sr{sub 2}Ca{sub 2}Cu{sub 3}O{sub 10} ((Bi,Pb)-2223) superconductor has been prepared. The effect of the PbO-CdO nanocomposite addition on the transport critical current density (J{sub c}) of (Bi,Pb)-2223 superconductor was investigated. The transition temperature (T{sub c-onset}), zero electrical resistance temperature (T{sub c-R=0}), and J{sub c} of the samples were measured by the four-probe method. Phase formation, structure, and microstructure of samples were investigated. The distribution of nanoparticle size was determined. The results indicated that the PbO-CdO-added samples showed larger grain size and an increased volume fraction of high-T{sub c} phase (Bi-2223) compared to the non-added sample. A slight increase in T{sub c-R=0} of x = 0.15 wt% was observed. J{sub c} of the PbO-CdO nanocomposite-added samples was significantly higher than for the non-added sample. That could be explained by the possibility that the PbO-CdO nanocomposite acts as an effective flux pinning center in (Bi,Pb)-2223. At 77 K, J{sub c} of x = 0.15 wt% added sample was more than 20 times larger than J{sub c} of the non-added sample (x = 0 wt%). A combined effect of enhanced flux pinning, increased fraction of high-T{sub c} phase and improved grain size, which led to increase in the J{sub c} of added samples, is discussed. (orig.)

  17. 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.

  18. Remediation of contaminated agricultural soils near a former Pb/Zn smelter in Austria: Batch, pot and field experiments

    International Nuclear Information System (INIS)

    Friesl, W.; Friedl, J.; Platzer, K.; Horak, O.; Gerzabek, M.H.

    2006-01-01

    Metal contaminated crops from contaminated soils are possible hazards for the food chain. The aim of this study was to find practical and cost-effective measures to reduce metal uptake in crops grown on metal contaminated soils near a former metal smelter in Austria. Metal-inefficient cultivars of crop plants commonly grown in the area were investigated in combination with in-situ soil amendments. A laboratory batch experiment using 15 potential amendments was used to select 5 amendments to treat contaminated soil in a pot study using two Barley (Hordeum vulgare L.) cultivars that differed in their ability to accumulate cadmium. Results from this experiment identified 3 of these amendments for use in a field trial. In the pot experiment a reduction in ammonium nitrate extractable Cd (<41%) and Pb (<49%) compared to the controls was measured, with a concurrent reduction of uptake into barley grain (Cd < 62%, Pb < 68%). In the field extractable fractions of Cd, Pb, and Zn were reduced by up to 96%, 99%, and 99%, respectively in amended soils. - Gravel sludge and red mud, combined with metal-excluding cultivars, can improve contaminated land

  19. Stable and luminescent wurtzite CdS, ZnS and CdS/ZnS core/shell quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Hitanshu; Barman, P.B.; Singh, Ragini Raj [Jaypee University of Information Technology, Department of Physics and Materials Science, Waknaghat, Solan, HP (India); Kumar, Manoj [Jaypee Institute of Information Technology, Department of Physics and Materials Science, Noida, Uttar Pradesh (India)

    2014-11-15

    This article presents first report on the highly stable and luminescent wurtzite CdS, ZnS and CdS/ZnS quantum dots (QDs) where the role of precursor selection at room temperature is the key. X-ray diffraction (XRD), optical absorbance spectroscopy, photoluminescence spectroscopy, Fourier transform infrared spectroscopy and transmission electron microscopy have been employed in order to characterize these QDs. XRD indicates the formation of wurtzite CdS, ZnS and CdS/ZnS system. Broadening in XRD peaks revealed the reduction in particle size such as 4.2, 5.2 and 5.8 nm for CdS, ZnS and CdS/ZnS, respectively, compared to their bulk counterparts. Blue shift in absorbance has been observed in each case as particles size decreases. The photoluminescence intensity emission of CdS/ZnS core/shell was strongly superior from that observed in individual CdS and ZnS nanoparticles. We also propose that the core and shell interface leads to favourable conditions that instigate photoluminescence emission in CdS/ZnS core/shell system. One notable result of this work obtained from the photoluminescence analysis is the significant reduction in full width at half maxima, in emission peak of core/shell structure which shows the enhanced monochromaticity. We have found that OH, CH{sub 2} and C-O functional groups are present on the QDs surface and that is why these QDs can be easily attachable to biomolecules. TEM analysis has been employed for confirmation of particle size and found to be 5.3, 5.8 and 6.2 nm for CdS, ZnS and CdS/ZnS structures, respectively. (orig.)

  20. Stable and luminescent wurtzite CdS, ZnS and CdS/ZnS core/shell quantum dots

    Science.gov (United States)

    Kumar, Hitanshu; Kumar, Manoj; Barman, P. B.; Singh, Ragini Raj

    2014-06-01

    This article presents first report on the highly stable and luminescent wurtzite CdS, ZnS and CdS/ZnS quantum dots (QDs) where the role of precursor selection at room temperature is the key. X-ray diffraction (XRD), optical absorbance spectroscopy, photoluminescence spectroscopy, Fourier transform infrared spectroscopy and transmission electron microscopy have been employed in order to characterize these QDs. XRD indicates the formation of wurtzite CdS, ZnS and CdS/ZnS system. Broadening in XRD peaks revealed the reduction in particle size such as 4.2, 5.2 and 5.8 nm for CdS, ZnS and CdS/ZnS, respectively, compared to their bulk counterparts. Blue shift in absorbance has been observed in each case as particles size decreases. The photoluminescence intensity emission of CdS/ZnS core/shell was strongly superior from that observed in individual CdS and ZnS nanoparticles. We also propose that the core and shell interface leads to favourable conditions that instigate photoluminescence emission in CdS/ZnS core/shell system. One notable result of this work obtained from the photoluminescence analysis is the significant reduction in full width at half maxima, in emission peak of core/shell structure which shows the enhanced monochromaticity. We have found that OH, CH2 and C-O functional groups are present on the QDs surface and that is why these QDs can be easily attachable to biomolecules. TEM analysis has been employed for confirmation of particle size and found to be 5.3, 5.8 and 6.2 nm for CdS, ZnS and CdS/ZnS structures, respectively.

  1. ZnS-Passivated CdSe/CdS Co-sensitized Mesoporous Zn2SnO4 Based Solar Cells

    International Nuclear Information System (INIS)

    Kim, Kyungho; Park, Ji Eun; Park, Eun Su; Park, Yun Chang; Kim, Joosun; Im, Chan; Lee, Man-Jong

    2014-01-01

    Graphical abstract: - Highlights: • Mesoporous Zn 2 SnO 4 sensitized by CdSe/CdS QDs were synthesized via a two-step sequential process. • Assembled QDs were characterized by HRTEM and STEM mapping. • Efficiency increase in CdSe/CdS co-sensitized Zn 2 SnO 4 DSSCs is discussed. • The role of ZnS passivation layer is discussed by impedance spectroscopy. - Abstract: CdS and CdSe/CdS quantum dot (QD) sensitizers were assembled onto mesoporous ternary Zn 2 SnO 4 photoanodes using a two-step sequential process of successive ionic layer absorption and reaction (SILAR) and chemical bath deposition (CBD) for QD-cosensitized solar cell applications. The assembled CdS and CdSe QDs were observed using high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), high-resolution TEM (HRTEM), and STEM/energy-dispersive X-ray spectroscopy (EDS) elemental mapping. CdSe/CdS cosensitized Zn 2 SnO 4 -based cells showed a higher absorption onset position, a stepwise band-edge level alignment, and, thereby, an improved power conversion efficiency (PCE) of 1.628% under one-sun conditions, which is the best result obtained using mesoporous Zn 2 SnO 4 reported to date. In addition, the effect of a ZnS passivation layer on the photovoltaic performance and aging behavior has been investigated. Electrochemical impedance spectroscopy (EIS) showed that the main role of the ZnS layer is to enhance the aging behavior of the CdSe/CdS/Zn 2 SnO 4 cells by improving the electron lifetime and charge recombination

  2. Comprehensive Study of All-Solid-State Z-Scheme Photocatalytic Systems of ZnO/Pt/CdZnS

    KAUST Repository

    Isimjan, Tayirjan Taylor

    2017-08-22

    We have investigated a Z-scheme based on a ZnO/Pt/CdZnS photocatalyst, active in the presence of a complex medium composed of acetic acid and benzyl alcohol, the effects of which on the catalyst stability and performance are studied. Transmission electron microscopy images showed uniformly dispersed sub-nanometer Pt particles. Inductively coupled plasma and X-ray photoelectron spectroscopy analyses suggested that Pt is sandwiched between ZnO and CdZnS. An apparent quantum yield (AQY) of 34% was obtained over the [ZnO]4/1 wt %Pt/CdZnS system at 360 nm, 2.5-fold higher than that of 1%Pt/CdZnS (14%). Furthermore, an AQY of 16% was observed using [ZnO]4/1 wt %Pt/CdZnS, which was comparable to that of 1 wt %Pt/CdZnS (10%) at 460 nm. On the basis of these results, we proposed a charge transfer mechanism, which was confirmed through femtosecond transient absorption spectroscopy. Finally, we identified the two main factors that affected the stability of the catalyst, which were the sacrificial reagent and the acidic pH.

  3. 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.

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

    Energy Technology Data Exchange (ETDEWEB)

    Cao Xinde [School of Environmental Science and Engineering, Shanghai Jiao Tong University, Shanghai 200240 (China)] [Soil and Water Science Department, University of Florida, Gainesville, FL 32611 (United States); Wahbi, Ammar [Soil Science Department, Faculty of Agriculture, University of Aleppo, Aleppo (Syrian Arab Republic); Ma, Lena, E-mail: lqma@ufl.edu [Soil and Water Science Department, University of Florida, Gainesville, FL 32611 (United States); Li Bing; Yang Yongliang [National Research Center for Geoanalysis, Beijing 100037 (China)

    2009-05-30

    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 H{sub 3}PO{sub 4} 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 H{sub 3}PO{sub 4} 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.

  5. A novel intermediate layer for Au/CdZnTe/FTO photoconductive structure

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yuelu; Wang, Linjun, E-mail: ljwang@shu.edu.cn; Xu, Run; Huang, Jian; Tao, Jun; Meng, Hua; Zhang, Jijun; Min, Jiahua

    2016-12-01

    Highlights: • Graphene layer was spin-coated on CdZnTe to form Au/graphene/CdZnTe/FTO structure. • Graphene layer can significantly improve the contact property of Au/CdZnTe. • Graphene layer can obviously enhance UV photo-response of CdZnTe. • Graphene is a potential buffer material for CdZnTe based high-energy detectors. - Abstract: In this work, graphene is tried to use to improve the performance of polycrystalline CdZnTe high-energy radiation and photon detectors. A graphene intermediate layer is prepared by spin-coating process on the surface of polycrystalline CdZnTe film, which forms a photoconductive Au/graphene/CdZnTe/FTO structure. XRD, Raman, photoelectric response and other characterisation methods are adopted to investigate the effect of graphene layer on the electrical characteristics and UV photo-response performance of CdZnTe photoconductive structure. It is demonstrated that graphene layer can significantly improve the contact property of Au/CdZnTe structure, and obviously enhance its UV photo-response and the UV sensitivity increased with one order of magnitude.

  6. Temperature-dependent exciton recombination in asymmetrical ZnCdSe/ZnSe double quantum wells

    CERN Document Server

    Yu Guang You; Zhang, J Y; Zheng, Z H; Yang, B J; Zhao Xiao Wei; Shen De Zhen; Kong Xiang Gui

    1999-01-01

    Temperature-dependent exciton recombination in asymmetrical ZnCdSe/ZnSe double quantum wells is studied by recording photoluminescence spectra and photoluminescence decay spectra. The exciton tunnelling from the wide well to the narrow well and the thermal dissociation of excitons are two factors that influence the exciton recombination in this structure. In the narrow well, both of the two processes decrease the emission intensity, whereas, in the wide well, these two processes have contrary influences on the exciton density. The change of the emission intensity depends on which is the stronger one. (author)

  7. Silver-bearing minerals in the Xinhua hydrothermal vein-type Pb-Zn deposit, South China

    Science.gov (United States)

    Wang, Minfang; Zhang, Xubo; Guo, Xiaonan; Pi, Daohui; Yang, Meijun

    2018-02-01

    Electron probe microanalysis (EPMA) results are reported for newly identified silver-bearing minerals from the Xinhua deposit, Yunkaidashan area, South China. The Xinhua deposit is a hydrothermal vein-type Pb-Zn deposit and is hosted in the Pubei Complex, which consists of a cordierite-biotite granite with a U-Pb zircon age of 244.3 ± 1.8-251.9 ± 2.2 Ma. The mineralization process is subdivided into four mineralization stages, characterized by the following mineral associations: mineralization stage I with quartz, pyrite, and sphalerite; mineralization stage II with siderite, galena, and tetrahedrite; mineralization stage III with quartz and galena; and mineralization stage IV with quartz, calcite, and baryte. Tetrahedrite series minerals, such as freibergite, argentotetrahedrite, and tennantite are the main Ag-bearing minerals in the Xinhua deposit. The greatest concentration of silver occurs in phases from mineralization stage II. Microscopic observations reveal close relationship between galena and tetrahedrite series minerals that mostly occur as irregular inclusions within galena. The negative correlation between Cu and Ag in the lattices of tetrahedrite series minerals suggests that Cu sites are occupied by Ag atoms. Zn substitution for Fe in argentotetrahedrite and Cd substitution for Pb in tetrahedrite are also observed. Micro-thermometric data reveal that both homogenization temperatures and calculated salinities of hydrothermal fluids decrease progressively from the early to the later mineralization stages. The metal ions, such as Ag+, Cu+, Pb2+, and Zn2+, are transported as chlorine complex ions in the early mineralization stage and as bisulfide complex ions in the late mineralization stage, caused by changes in oxygen fugacity, temperature, and pH of the hydrothermal fluids. Because of the varying solubility of different metal ions, Pb2+, Zn2+, and Cu2+ ions are initially precipitated as galena, sphalerite, and chalcopyrite, respectively. With

  8. Etch Pit Studies of II-VI-Wide Bandgap Semiconductor Materials ZnSe, ZnCdSe, and ZnCdMgSe Grown on InP

    National Research Council Canada - National Science Library

    Semendy, Fred

    1999-01-01

    Etch pit density (EPD) determination studies have been conducted on II-VI semiconductor materials ZnSe, ZnCdSe, and ZnCdMgSe grown on InP surfaces for the first time by using various etching solutions under different...

  9. Differential tolerance of Agrostis tenuis populations growing at two mine soils to Cu, Zn, and Pb

    Energy Technology Data Exchange (ETDEWEB)

    Karataglis, S.S.

    1980-01-01

    The Cu, Zn and Pb tolerance of Agrostis tenuis Sibth. populations found in the area of two mines in England as well as in uncontaminated areas were studied by determining the effect of these metals on the rooting of tillers. The populations proved tolerant to the particular metals present in high quantities in the soil of their original habitats as compared to the populations collected from uncontaminated soil. The populations of the Trelogan mine were tolerant only to Zn and not to Cu and Pb. On the contrary, the populations in the mine of Parys Mountain were highly tolerant to all these metals. A linear correlation in the index of tolerance between Zn and Pb in both mines was found suggesting the possibility of a physiological association of the tolerance mechanisms to these two elements.

  10. Speciation and mobility of Zn, Cu and Pb in a truck farming soil contaminated by sewage irrigation

    Science.gov (United States)

    Kirpichtchikova, T.; Manceau, A.; Lanson, B.; Marcus, M. A.; Jacquet, T.

    2003-05-01

    The forrns and mobility of Cu (290 mg/kg), Zn (1103 mg/kg), and Pb (535 mg/kg) in a soil used for intensive truck farining from the Region Ile-de-France, and which has been irrigated for more than a century with sewage water ftom the city of Paris, have been studied by chemical treatments and advanced x-ray techniques. Elemental associations and forms of metals were determined qualitatively and quantitatively by a combination of physical techniques, including μPIXE (Cu, Zn, Pb), μSXRF (Cu, Zn), μEXAFS (Zn) and powder EXAFS (Zn). The nature, number, and relative proportion of Zn species were obtained by principal component analysis and decomposition of Zn K-edge EXAFS spectra. These data collectively indicate that Cu is associated mainly with organic matter, and that Zn and Pb are bound essentially to mineral constituents. Four Zn-containing species were positively identified: Zn-phosphate and phyllosilicate as dominant species, and Zn-Fe oxyhydroxide and willemite (Zn2SiO4) as minor species. Studies are underway to determine the structural forms of Cu and Pb. Depending on the chemical treatment, up to 70% Cu, ~50% Zn, and ~85% Pb can be removed in a few days with citrate and EDTA. Citrate is generally at least as efficient as EDTA, and it has the advantage ofbeing easily biodegradable and, hence, less harmful to ecosystems.

  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. Fast Neutron Detection Using Pixelated CdZnTe Spectrometers

    Science.gov (United States)

    Streicher, Michael; Goodman, David; Zhu, Yuefeng; Brown, Steven; Kiff, Scott; He, Zhong

    2017-07-01

    Fast neutrons are an important signature of special nuclear materials (SNMs). They have a low natural background rate and readily penetrate high atomic number materials that easily shield gamma-ray signatures. Therefore, they provide a complementary signal to gamma rays for detecting shielded SNM. Scattering kinematics dictate that a large nucleus (such as Cd or Te) will recoil with small kinetic energy after an elastic collision with a fast neutron. Charge carrier recombination and quenching further reduce the recorded energy deposited. Thus, the energy threshold of CdZnTe detectors must be very low in order to sense the small signals from these recoils. In this paper, the threshold was reduced to less than 5 keVee to demonstrate that the 5.9-keV X-ray line from 55Fe could be separated from electronic noise. Elastic scattering neutron interactions were observed as small energy depositions (less than 20 keVee) using digitally sampled pulse waveforms from pixelated CdZnTe detectors. Characteristic gamma-ray lines from inelastic neutron scattering were also observed.

  13. Study of extending carrier lifetime in ZnTe quantum dots coupled with ZnCdSe quantum well

    Science.gov (United States)

    Fan, W. C.; Chou, W. C.; Lee, J. D.; Lee, Ling; Phu, Nguyen Dang; Hoang, Luc Huy

    2018-03-01

    We demonstrated the growth of a self-assembled type-II ZnTe/ZnSe quantum dot (QD) structure coupled with a type-I Zn0.88Cd0.12Se/ZnSe quantum well (QW) on the (001) GaAs substrate by molecular beam epitaxy (MBE). As the spacer thickness is less than 2 nm, the carrier lifetime increasing from 20 ns to nearly 200 ns was successfully achieved. By utilizing the time-resolved photoluminescence (TRPL) and PL with different excitation power, we identify the PL emission from the coupled QDs consisting of two recombination mechanisms. One is the recombination between electrons in ZnSe barrier and holes confined within ZnTe QDs, and the other is between electrons confined in Zn0.88Cd0.12Se QW and holes confined within ZnTe QDs. According to the band diagram and power-dependent PL, both of the two recombinations reveal the type-II transition. In addition, the second recombination mechanism dominates the whole carrier recombination as the spacer thickness is less than 2 nm. A significant extension of carrier lifetime by increasing the electron and hole separation is illustrated in a type-II ZnTe/ZnSe QD structure coupling with a type-I ZnCdSe/ZnSe QW. Current sample structure could be used to increase the quantum efficient of solar cell based on the II-VI compound semiconductors.

  14. CdCl{sub 2} treatment related diffusion phenomena in Cd{sub 1−x}Zn{sub x}S/CdTe solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Kartopu, G., E-mail: giray.kartopu@glyndwr.ac.uk; Clayton, A. J.; Barrioz, V.; Lamb, D. A.; Irvine, S. J. C. [Centre for Solar Energy Research (CSER), Glyndŵr University, OpTIC, St. Asaph Business Park, St. Asaph LL17 0JD (United Kingdom); Taylor, A. A. [Physics Department, Durham University, Durham DH1 3LE (United Kingdom)

    2014-03-14

    Utilisation of wide bandgap Cd{sub 1−x}Zn{sub x}S alloys as an alternative to the CdS window layer is an attractive route to enhance the performance of CdTe thin film solar cells. For successful implementation, however, it is vital to control the composition and properties of Cd{sub 1−x}Zn{sub x}S through device fabrication processes involving the relatively high-temperature CdTe deposition and CdCl{sub 2} activation steps. In this study, cross-sectional scanning transmission electron microscopy and depth profiling methods were employed to investigate chemical and structural changes in CdTe/Cd{sub 1−x}Zn{sub x}S/CdS superstrate device structures deposited on an ITO/boro-aluminosilicate substrate. Comparison of three devices in different states of completion—fully processed (CdCl{sub 2} activated), annealed only (without CdCl{sub 2} activation), and a control (without CdCl{sub 2} activation or anneal)—revealed cation diffusion phenomena within the window layer, their effects closely coupled to the CdCl{sub 2} treatment. As a result, the initial Cd{sub 1−x}Zn{sub x}S/CdS bilayer structure was observed to unify into a single Cd{sub 1−x}Zn{sub x}S layer with an increased Cd/Zn atomic ratio; these changes defining the properties and performance of the Cd{sub 1−x}Zn{sub x}S/CdTe device.

  15. Synthesis of ZnO/CdSe hierarchical heterostructure with improved visible photocatalytic efficiency

    International Nuclear Information System (INIS)

    Wu, Yao; Xu, Fang; Guo, Defu; Gao, Zhiyong; Wu, Dapeng; Jiang, Kai

    2013-01-01

    ZnO/CdSe hierarchical heterostructure was prepared using pompon-like ZnO as substrate materials, and hexagonal CdSe nanoparticles were dispersed on the ZnO plates. The hybrid ZnO/CdSe samples were intensively investigated by XRD, SEM, TEM, HRTEM, PL and UV–vis absorption spectrum. The photocatalytic experiments confirm that ZnO/CdSe heterostructure exhibits improved photocatalytic efficiency compared to pure ZnO under visible light irradiation. CdSe nanoparticles are believed to serve as photosensitizers to extend the absorption spectrum to visible light region. In addition, the incorporation of CdSe can suppress the recombination of photogenerated electron-hole pairs, which contributes to the enhancement of photocatalytic efficiency.

  16. Effects of Cu, Zn and Pb Combined Pollution on Soil Hydrolase Activities

    Directory of Open Access Journals (Sweden)

    FENG Dan

    2015-08-01

    Full Text Available To study the relations between soil enzyme activities and heavy metal pollution, the combined effects of Cu, Zn and Pb on the three hydrolase activities, including invertase(IN, urease(Uand alkaline phosphatase(ALPwere investigated via an orthogonal experiment. Results showed as the following: When the concentration of Cu was 400 mg·kg-1, the U and ALP activities were decreased 51% and 44%, separately; When Zn was at 500 mg·kg-1, IN and ALP activities were only decreased 3% and 9%, while U activity was increased; When Pb was at 500 mg·kg-1, IN and U activities were increased, while ALP activity was decreased 13%. As a whole, Cu was considered as the most remarkable influence factor for IN, U and ALP activity regardless of interactions among the heavy metals, Zn came second, and Pb mainly showed activation. Considering interactions, Cu×Zn could significantly influence U activity(P<0.05, effects of Cu×Pb and Cu×Zn on ALP activity were remarkable(95% confidence interval. The response of ALP activity was more sensitive than the other two enzymes. Soil ALP activity might be a sensitive tool for assessing the pollution degree of Cu.

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

    International Nuclear Information System (INIS)

    Moffet, Ryan C.; Desyaterik, Yury; Hopkins, Rebecca J.; Tivanski, Alexei V.; Gilles, Marry K.; Wang, Yan A.; Shutthanandan, V.; Molina, Luisa T.; Abraham, Rodrigo G.; Johnson, Kirsten S.; Mugica, Violeta; Molina, Mario J.; Laskin, Alexander; Prather, Kimberly A.

    2008-01-01

    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

  18. Synthesis of CdO/ZnS heterojunction for photodegradation of organic dye molecules

    Science.gov (United States)

    Venkata Reddy, Ch.; Bandaru, Narendra; Shim, Jaesool; Vattikuti, S. V. Prabhakar

    2017-06-01

    CdO, ZnS, and CdO/ZnS hybrid photocatalyst were prepared using a simple co-precipitation method, and its photocatalytical activity was studied. The materials were characterized using powder XRD, TEM, HRTEM, BET, Raman, optical absorption, FT-IR, Thermal analysis and PL. The XRD patterns confirmed the crystal structure of the prepared samples. The surface analysis shows that the CdO/ZnS hybrid photocatalyst have larger surface area than the CdO and ZnS. Optical analysis of the nanocomposites revealed that the bond energy decreased after adding ZnS nanoparticles due to interactions with CdO nanoparticles. Raman spectroscopy showed the phonon modes of the CdO and ZnS, and PL spectra showed the electronic interaction between them. The photo-induced electrons can be easily transferred from the CdO to the ZnS in the composite, which facilitates effective charge separation and enhances photocatalytic degradation. The highest photocatalytic activity was achieved using the CdO/ZnS hybrid photocatalyst, with which more than 92% degradation was achieved. The enhanced photocatalytic activity could be ascribed to the low recombination rate of the electron and hole pairs because of the interface action between the CdO and ZnS.

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

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Jingwei; Li, Dongmei, E-mail: dmli@mail.shu.edu.cn; Cheng, Tao; Ren, Bing; Wang, Gang; Li, Jie

    2014-03-15

    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.

  20. Synthesis of CdO/ZnS heterojunction for photodegradation of organic dye molecules

    Energy Technology Data Exchange (ETDEWEB)

    Venkata Reddy, C.; Shim, Jaesool; Vattikuti, S.V.P. [YeungnamUniversity, School of Mechanical Engineering, Gyeongsan-si, Gyeongsangbuk-do (Korea, Republic of); Bandaru, Narendra [IIT Gandhi Nagar, Department of Material Science and Engineering, Ahmedabad (India)

    2017-06-15

    CdO, ZnS, and CdO/ZnS hybrid photocatalyst were prepared using a simple co-precipitation method, and its photocatalytical activity was studied. The materials were characterized using powder XRD, TEM, HRTEM, BET, Raman, optical absorption, FT-IR, Thermal analysis and PL. The XRD patterns confirmed the crystal structure of the prepared samples. The surface analysis shows that the CdO/ZnS hybrid photocatalyst have larger surface area than the CdO and ZnS. Optical analysis of the nanocomposites revealed that the bond energy decreased after adding ZnS nanoparticles due to interactions with CdO nanoparticles. Raman spectroscopy showed the phonon modes of the CdO and ZnS, and PL spectra showed the electronic interaction between them. The photo-induced electrons can be easily transferred from the CdO to the ZnS in the composite, which facilitates effective charge separation and enhances photocatalytic degradation. The highest photocatalytic activity was achieved using the CdO/ZnS hybrid photocatalyst, with which more than 92% degradation was achieved. The enhanced photocatalytic activity could be ascribed to the low recombination rate of the electron and hole pairs because of the interface action between the CdO and ZnS. (orig.)

  1. Evidence for microbial activity in the formation of carbonate-hosted Zn-Pb deposits

    Science.gov (United States)

    Kucha, H.; Raith, J.

    2009-04-01

    *Kucha H **Raith J *University of Mining and Metallurgy, Faculty of Geology, Geophysics and Environmental Protection, Mickiewicza 30, PL-30-059 Krakow, Poland. ** University of Leoben, Department of Applied Geosciences and Geophysics, A-8700 Leoben, Peter Tunner Str. 5, Austria Evidence for microbial activity in the formation of carbonate-hosted Zn-Pb deposits To date evaluation of bacterial processes in the formation of carbonate-hosted Zn-Pb deposits is largely based on sulphur isotope evidence. However, during a past few years, textural criteria, have been established, which support the bacterial origin of many of these deposits. This has received a strong support from micro-, and nano-textures of naturally growing bacterial films in a flooded tunnel within carbonates that host the Piquette Zn-Pb deposit (Druschel et al., 2002). Bacterial textures, micro- and nano textures found in carbonate-hosted Zn-Pb deposits are: i)wavy bacterial films up to a few mm thick to up to a few cm long composed of peloids, ii)semimassive agglomeration of peloids in the carbonate matrix, and iii)solitary peloids dispersed in the carbonate matrix. Peloids are usually composed of a distinct 50-90um core most often made up of Zn-bearing calcite surrounded by 30-60um thick dentate rim composed of ZnS. Etching of Zn-carbonate cores reveals 1 - 2um ZnS filaments, and numerous 15 to 90nm large ZnS nano-spheres (Kucha et al., 2005). In massive ore composite Zn-calcite - sphalerite peloids are entirely replaced by zinc sulphide, and form peloids ghosts within banded sulphide layers. Bacterially derived micro- and nano-textures have been observed in the following carbonate-hosted Zn-Pb deposits: 1)Irish-type Zn-Pb deposits. In the Navan deposit the basic sulphur is isotopically light bacteriogenic S (Fallick at al., 2001). This is corroborated by semimassive agglomerations of composite peloids (Zn-calcite-ZnS corona or ZnS core-melnikovite corona). Etching of Zn-calcite core reveals globular

  2. Piezoelectric effect in CdTe/CdMnTe and CdTe/CdZnTe quantum wells

    International Nuclear Information System (INIS)

    Andre, Regis

    1994-01-01

    Materials with zinc-blende type structure are piezoelectric: any strain along a polar axis generates an electrical polarisation. Strained quantum wells of cubic II-VI or III-V semiconductors, grown along [111] or [112] axis, exhibit a strong built-in piezo-electric field (100 kV/cm for 1% strains). Such structures are very promising for applications to optical modulation, but it is necessary to study first the physical properties of piezoelectric heterostructures before they can be used in optical devices. For this purpose, we have performed an optical study of strained CdTe/CdMnTe or CdTe/CdZnTe quantum wells coherently grown by molecular beam epitaxy on [111] or [112] oriented substrates. Effects of piezoelectric field on optical and electronic properties of quantum wells have been analyzed in terms of the envelop function model, taking into account the effects of biaxial strains for [hhk] growth axis. Moreover, we have proposed an original way of measuring piezoelectric field in strained quantum wells, and we have used this method to show that CdTe exhibits strong non-linearities for piezoelectric field versus strain. This effect has never been mentioned before. We have also performed measurements of the piezoelectric coefficient e14 under high hydrostatic pressure inducing strains up to 2%, which shows that part of the non-linear effect is a volume effect. We have also studied the effects of the piezoelectric field on excitons in quantum wells. The binding energy decreases slightly when the electric field increases, but the oscillator strength, for the fundamental transition, decreases dramatically with the overlap of the envelope wavefunctions of electrons and holes. We have performed a modelization of an exciton in a piezoelectric quantum well using two variational parameters. This model provides an accurate calculation of excitonic absorption. Our experimental and theoretical results are in very good agreement, without any fitting parameters, for a large

  3. 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 ...

  4. Distribution of toxic metals, Hg, Cd and Pb in zooplankton along the Indian coasts

    Digital Repository Service at National Institute of Oceanography (India)

    Sengupta, R.; Kureishy, T.W.

    and in the marine food chain is also attempted. The results have shown high concentrations of Cd and Pb in zooplankton collected from the East Coast as compared to the West Coast. Some inferences have been drawn...

  5. Investigation of biocompatible and protein sensitive highly luminescent quantum dots/nanocrystals of CdSe, CdSe/ZnS and CdSe/CdS

    Science.gov (United States)

    Ratnesh, R. K.; Mehata, Mohan Singh

    2017-05-01

    The size and shape dependent semiconductor quantum dots (0D nanoparticles) with color tunability demonstrating significant influence in a biological system and considered as ideal probes. Here, a non-coordinated colloidal approach was used for the synthesis of CdSe, CdSe/ZnS and CdSe/CdS core-shell quantum dots (QDs) of 3-4 nm. The synthesized nanocrystals show a high crystallinity, examined by X-ray diffraction (XRD) and high-resolution electron microscopy (HRTEM). The core-shell semiconductor QDs exhibit stronger photoluminescence (PL) as compared to the core QDs. The strong PL with small full-width half maximum (FWHM) indicates that the prepared QDs have a nearly uniform size distribution and well dispersibility. The quantum yield (QY) of core-shell QDs increases due to the surface passivation. Further, the PL of BSA is quenched strongly by the presence of core-shell QDs and follows the well-known Stern-Volmer (S-V) relation, whereas the PL lifetime does not follow the S-V relation, demonstrating that the observed quenching is predominantly static in nature. Among CdSe core, CdSe/ZnS and CdSe/CdS core-shell QDs, the CdSe/ZnS QDs shows the least cytotoxicity and most biocompatibility. Thus, the prepared core-shell QDs are biocompatible and exhibit strong sensing ability.

  6. Heavy metal (Pd, Cd, Fe, Zn and Mn) levels in sediments from Nigerian Coastal waters.

    Science.gov (United States)

    Oguguah, N. M.

    2016-02-01

    Sediments collected during a pollution monitoring cruise carried out on Nigerian coastal waters by Nigerian Institute for Oceanography and Marine Research Lagos was analysed for heavy metals. A trawler MS Suzzannah with an on board GPS was used to locate bearings of 25 sampling points (N06o30 and E003o30). Eckman grab was deployed and used in collecting bottom sediments. The sediment were air dried and digested using the method of GEF GCLME. The samples were analysed in five replicates for heavy metals (Pd, Cd, Fe, Zn and Mn) using Varian AA 600 Atomic Absorption Spectrometer. The highest concentration of Pb was transect R (10.93) and the least concentration (0.059) was in transect C. The highest concentration of Cd was transect H (0.75) and the least concentration (0.044) was in transect C. The highest concentration of Fe was transect M (203.582) and the least concentration (2.232) was in transect C. The highest concentration of Zn was transect H (4.595) and the least concentration (0.174) was in transect F. The highest concentration of Mn was transect H (209.251) and the least concentration (0.167) was in transect C.

  7. 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.)

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

    International Nuclear Information System (INIS)

    Liu, Shuling; Li, Honglin; Yan, Lu

    2013-01-01

    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 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

  9. Bioakumulasi timbal (Pb) dan cadmium (Cd) pada Lamun Cymodocea serrulata di Perairan Bangka Selatan

    OpenAIRE

    Suci Puspita Sari; Dwi Rosalina; Wahyu Adi

    2017-01-01

    The purpose of this study was to measure the heavy metal content of cadmium (Cd) and lead (Pb) in water, sediment and seagrass Cymodocea serrulata from Southern Bangka waters. The research was conducted in two locations in South Bangka Regency, namely Desa Pasir Putih and Tanjung Kerasak.The sediments, waters, and seagrass were collected using purposive random sampling method. Measurement of water quality data was in situ. Seagrass sampling is done by transect method. The Cd and Pb contents i...

  10. Content Heavy Metal Pb, Cd In Perna viridis And Sediments In Semarang Bay

    Science.gov (United States)

    Suprapto, D.; Suryanti, S.; Latifah, N.

    2018-02-01

    Waste disposal from human activities, generally contain heavy metals such as Pb and Cd which derived from industrial activities. The aims of the study were to know the concentration of Pb and Cd heavy metals contained in Perna viridis tissue, sediment and water at Semarang Bay. This study was conducted in May 2017 at Semarang Bay. - Samples were collected using purposive sampling method. The heavy metal content in the water and clam was observed using- APHA method and was analyzed using AAS (Atomic Absorption Spectrophotometer). The results showed that concentration of heavy metal of Pb in the water was 0.00-50.5mg/L and the Cd content was of 26.9-51.7 mg/L, whereas the concentration of Pb in the sediment is 445.5-2.053.0mg/L and Cd 963.3-2,150.0 mg/L. Pb content in soft tissue of Perna viridis - is 67.1-1.933.9 mg/L and the concentration of Cd was 203.5-5.787.3 mg/L. The analysis of Pb and Cd in seawater, sediment and soft tissue of Perna viridis according to Enviroment Ministerial decree (KepMenLH ) number 51 of 2004 and applied by NOAA 1999 does not exceed the quality standard, that meant that the Perna viridis has been contaminated by metal Pb it is controversial with the above sentence and Cd. It concluded that the metal content of Pb and Cd in Perna viridis tissue exceeds the quality standard, so it is not suitable to be consumed, especially in high quantity

  11. Bioakumulasi timbal (Pb dan cadmium (Cd pada Lamun Cymodocea serrulata di Perairan Bangka Selatan

    Directory of Open Access Journals (Sweden)

    Suci Puspita Sari

    2017-08-01

    Full Text Available The purpose of this study was to measure the heavy metal content of cadmium (Cd and lead (Pb in water, sediment and seagrass Cymodocea serrulata from Southern Bangka waters. The research was conducted in two locations in South Bangka Regency, namely Desa Pasir Putih and Tanjung Kerasak.The sediments, waters, and seagrass were collected using purposive random sampling method. Measurement of water quality data was in situ. Seagrass sampling is done by transect method. The Cd and Pb contents in the Water, sediments and sea grass samples were analyzed using Atomic Absorption Spectrophotometer (AAS. The results showed that Cd concentration in water was higher than Pb, with the range of between 0.29 to 0.39 mg/l. Pb was higher than Cd in the sediment ranges between 4.74 to 7.68 mg/kg. The highest Cd concentration was detected at the seagrass leaf with a range of 1.76⎼2.44 mg/kg, while the highest Pb concentration at the seagrass roots ranged from 1.94 ⎼ 6.52 mg/kg. The high content of heavy metals Cd and Pb on seagrass sections, when compared to water and sediments, shows that seagrass accumulates metals derived from water and sediment. The Bioconcentration factor (BCF showed that seagrass leaves can accumulate Cd of 6.16 and Pb of 5.31. While The BCF value of the seagrass roots is able to accumulate Cd of 0.53 and metal Pb of 0.55 Penelitian ini bertujuan untuk mengukur kandungan logam berat cadmium (Cd dan timbal (Pb pada air, sedimen dan lamun Cymodocea serrulata. Penelitian dilakukan di 2 lokasi di Kabupaten Bangka Selatan, yaitu Desa Pasir Putih dan Tanjung Kerasak. Metode Penelitian merupakan penelitian survei dengan pendekatan kuantitatif. Sampling dalam penelitian ini meliputi sampling kualitas, pengambilan sampel air, sedimen dan lamun menggunakan metode Purposive Random Sampling. Pengukuran data kualitas air dilakukan secara insitu. Pengambilan sampel lamun dilakukan dengan metode transect. Sampel air, sedimen dan lamun dianalisis

  12. Origin of luminescence from ZnO/CdS core/shell nanowire arrays

    Science.gov (United States)

    Wang, Zhiqiang; Wang, Jian; Sham, Tsun-Kong; Yang, Shaoguang

    2014-07-01

    Chemical imaging, electronic structure and optical properties of ZnO/CdS nano-composites have been investigated using scanning transmission X-ray microscopy (STXM), X-ray absorption near-edge structure (XANES) and X-ray excited optical luminescence (XEOL) spectroscopy. STXM and XANES results confirm that the as-prepared product is ZnO/CdS core/shell nanowires (NWs), and further indicate that ZnS was formed on the surface of ZnO NWs as the interface between ZnO and CdS. The XEOL from ZnO/CdS NW arrays exhibits one weak ultraviolet (UV) emission at 375 nm, one strong green emission at 512 nm, and two broad infrared (IR) emissions at 750 and 900 nm. Combining XANES and XEOL, it is concluded that the UV luminescence is the near band gap emission (BGE) of ZnO; the green luminescence comes from both the BGE of CdS and defect emission (DE, zinc vacancies) of ZnO; the IR luminescence is attributed to the DE (bulk defect related to the S site) of CdS; ZnS contributes little to the luminescence of the ZnO/CdS NW arrays. Interestingly, the BGE and DE from oxygen vacancies of ZnO in the ZnO/CdS nano-composites are almost entirely quenched, while DE from zinc vacancies changes little.Chemical imaging, electronic structure and optical properties of ZnO/CdS nano-composites have been investigated using scanning transmission X-ray microscopy (STXM), X-ray absorption near-edge structure (XANES) and X-ray excited optical luminescence (XEOL) spectroscopy. STXM and XANES results confirm that the as-prepared product is ZnO/CdS core/shell nanowires (NWs), and further indicate that ZnS was formed on the surface of ZnO NWs as the interface between ZnO and CdS. The XEOL from ZnO/CdS NW arrays exhibits one weak ultraviolet (UV) emission at 375 nm, one strong green emission at 512 nm, and two broad infrared (IR) emissions at 750 and 900 nm. Combining XANES and XEOL, it is concluded that the UV luminescence is the near band gap emission (BGE) of ZnO; the green luminescence comes from both the

  13. Tunable narrow emission in ZnS/CdS/ZnS quantum well structures prepared by aqueous route

    Science.gov (United States)

    Kumar, Hitanshu; Kumari, Asha; Singh, Ragini Raj

    2017-07-01

    ZnS/CdS/ZnS quantum wells (QWs) with tunable narrow emission due to narrow size distribution were successfully synthesized by wet chemical method. QWs give high luminescence and hence important materials for recent nanotechnology applications such as optoelectronics and bioimaging. In this work we put forward a QW structure with extended potential barrier, where electron and holes are confining in the core of ZnS and ZnS/CdS QDs by creating a ZnS/CdS/ZnS potential well like structure. Multilayers break the continuity of structure, which gives the combined advantages of ZnS, CdS and ZnS/CdS. This well like structure of quantum dots gives highest possibility to confine the electron and holes inside core and enhance the optical properties with suitable shell thickness. Structural, morphological and optical properties were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-visible absorption (UV-vis) and photoluminescence (PL) spectroscopy. Quantum yield of these quantum dot structures was also measured.

  14. Spectroscopic ellipsometry studies on ZnCdO thin films with different Cd concentrations grown by pulsed laser deposition

    Science.gov (United States)

    Chen, Shuai; Li, Qingxuan; Ferguson, Ian; Lin, Tao; Wan, Lingyu; Feng, Zhe Chuan; Zhu, Liping; Ye, Zhizhen

    2017-11-01

    A set of Zn1-xCdxO thin films with different Cd concentrations was deposited on quartz substrates by Pulsed Laser Deposition (PLD). The properties of these films were investigated by variable angle and temperature dependent spectroscopic ellipsometry (SE). The experimental Zn1-xCdxO thin films showed a red shift in the absorption edge with increasing Cd contents at room temperature. For ZnCdO films with the similar Cd concentration, it has been found that the film thickness has important effects on the optical constants (n, k). The variations of optical constants (n, k) and the band gap, E0, with temperature (T) in 25 °C-600 °C for a typical Zn0.95Cd0.05O sample were obtained. The E0 vs T relationship is described by a T- quadratic equation.

  15. Investigation of composition dependent structural and optical properties of the Zn(1-x)Cd(x)S, coaxial Zn(0.99-x)Cd(x)Cu(0.01)S/ZnS, Zn(0.99-x)Cd(x)Mn(0.01)S nanorods generated by a one-step hydrothermal process.

    Science.gov (United States)

    Han, Donglai; Cao, Jian; Yang, Shuo; Yang, Jinghai; Wang, Bingji; Fan, Lin; Liu, Qianyu; Wang, Tingting; Niu, Haifeng

    2014-07-28

    High-quality Zn(1-x)Cd(x)S, coaxial Zn(0.99-x)Cd(x)Cu(0.01)S/ZnS and Zn(0.99-x)Cd(x)Mn(0.01)S nanorods (NRs) were synthesized through a one-step hydrothermal method. The composition of the alloyed NRs was adjusted by controlling the Zn/Cd molar ratios. The results showed that all of the samples had a good crystallinity with the typical hexagonal wurtzite structure. The Zn/Cd molar ratios and Cu and Mn doping played an important role in affecting the final structure, morphology and optical properties of the alloyed NRs. The successive shift of the XRD and PL patterns indicated that the NRs obtained were not a mixture of ZnS and CdS, but the Zn(1-x)Cd(x)S solid solution. After doping Cu(2+) (1%) ions into the Zn(1-x)Cd(x)S NRs, the samples exhibited highly crystalline coaxial Zn(0.99-x)Cd(x)Cu(0.01)S/ZnS core-shell NRs and showed a strong green emission peak centered at 509.6 nm. After doping Mn(2+) (1%) ions into the Zn(1-x)Cd(x)S NRs, the samples exhibited a better crystal quality and showed a strong yellow-orange emission peak centered at 583 nm.

  16. 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.

  17. Vapour growth of Cd(Zn)Te columnar nanopixels into porous alumina

    International Nuclear Information System (INIS)

    Sochinskii, N.V.; Abellan, M.; Martin Gonzalez, M.; Saucedo, E.; Dieguez, E.; Briones, F.

    2006-01-01

    The vapour phase growth (VPG) of CdTe and Cd 1- x Zn x Te was performed in order to investigate the formation of Cd(Zn)Te columnar nanostructures, which could serve as a basis for micropixels usable for further development of X- and gamma-ray high-resolution imaging devices. The possibility to form the 'Cd(Zn)Te-in-porous alumina' nanostructures by VPG has been demonstrated. The Cd(Zn)Te crystals integrated into nanoporous alumina have shown to have photoluminescence properties compatible with those of the bulk crystals and planar epitaxial layers. Further investigations are going on to improve the structural quality of Cd(Zn)Te nanocrystals

  18. Removal of Zn(II) and Pb (II) ions Using Rice Husk in Food Industrial ...

    African Journals Online (AJOL)

    Michael Horsfall

    Hanafiah and et al., 2007), grape ... with tap water and then deionized water to remove particulate material from their surface. After that, they were ... a prescribed length of time by magnetic stirrer. After filtration thorough the filter paper, Zn2+ and Pb2+ ...

  19. Biosorption of Zinc (Zn) and lead (Pb) by metal resistant bacterial isolate from mining tail

    Energy Technology Data Exchange (ETDEWEB)

    Bautista Hernandez, D. A.; Carranza Alvarado, M.; Fernandez Linares, L.; Ramirez Landy, I.

    2009-07-01

    The use of microbial biomass in the removal of metals in solution, mainly of low concentrations (100 mg L{sup -}1), present advantages in relation to the physicochemical methods. The resistant microorganisms are potential bio sorbents. The objective of the present study was the isolation, starting from mining tail, of strains with capacity of metal bio sorption (Zn and Pb). (Author)

  20. Biosorption of Zinc (Zn) and lead (Pb) by metal resistant bacterial isolate from mining tail

    International Nuclear Information System (INIS)

    Bautista Hernandez, D. A.; Carranza Alvarado, M.; Fernandez Linares, L.; Ramirez Landy, I.

    2009-01-01

    The use of microbial biomass in the removal of metals in solution, mainly of low concentrations (100 mg L - 1), present advantages in relation to the physicochemical methods. The resistant microorganisms are potential bio sorbents. The objective of the present study was the isolation, starting from mining tail, of strains with capacity of metal bio sorption (Zn and Pb). (Author)

  1. Removal of Pb and Zn from Soil using cowpea ( Vigna unguiculata ...

    African Journals Online (AJOL)

    Zea mays) plants to remove Pb and Zn from soil. The crops were exposed to three concentrations (100, 150 and 200 mgkg-1) of each metal salts during the study. When the plants were treated with lead nitrate at a concentration of 150 mgkg-1, ...

  2. 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

  3. Electron density distribution and bonding in ZnSe and PbSe using ...

    Indian Academy of Sciences (India)

    Unknown

    directions are relatively low in conformity with the loosely packed structure of ZnSe. (The interaction of atomic charges will be less and hence the electron densities along directions other than bonding are expected to be minimum). Figure 8(b) of PbSe shows unequal electron densities along the three directions. This is due ...

  4. 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.

  5. CdSe/CdS/ZnS double shell nanorods with high photoluminescence efficiency and their exploitation as biolabeling probes.

    Science.gov (United States)

    Deka, Sasanka; Quarta, Alessandra; Lupo, Maria Grazia; Falqui, Andrea; Boninelli, Simona; Giannini, Cinzia; Morello, Giovanni; De Giorgi, Milena; Lanzani, Guglielmo; Spinella, Corrado; Cingolani, Roberto; Pellegrino, Teresa; Manna, Liberato

    2009-03-04

    We report the synthesis, the structural and optical characterization of CdSe/CdS/ZnS "double shell" nanorods and their exploitation in cell labeling experiments. To synthesize such nanorods, first "dot-in-a-rod" CdSe(dot)/CdS(rod) core/shell nanocrystals were prepared. Then a ZnS shell was grown epitaxially over these CdSe/CdS nanorods, which led to a fluorescence quantum yield of the final core-shell-shell nanorods that could be as high as 75%. The quantum efficiency was correlated with the aspect ratio of the nanorods and with the thickness of the ZnS shell around the starting CdSe/CdS rods, which varied from 1 to 4 monolayers (as supported by a combination of X-ray diffraction, elemental analysis with inductively coupled plasma atomic emission spectroscopy and high resolution transmission electron microscopy analysis). Pump-probe and time-resolved photoluminescence measurements confirmed the reduction of trapping at CdS surface due to the presence of the ZnS shell, which resulted in more efficient photoluminescence. These double shell nanorods have potential applications as fluorescent biological labels, as we found that they are brighter in cell imaging as compared to the starting CdSe/CdS nanorods and to the CdSe/ZnS quantum dots, therefore a lower amount of material is required to label the cells. Concerning their cytotoxicity, according to the MTT assay, the double shell nanorods were less toxic than the starting core/shell nanorods and than the CdSe/ZnS quantum dots, although the latter still exhibited a lower intracellular toxicity than both nanorod samples.

  6. Influence of Zn and Pb on Rhizopogon roseolus mycelium - energy dispersion spectroscopy and cytochemical investigation

    Directory of Open Access Journals (Sweden)

    Katarzyna Turnau

    2014-01-01

    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.

  7. New heterostructures n-PbS-n-ZnSe: long-term stability of photosensitivity

    International Nuclear Information System (INIS)

    Khlyap, G.; Andrukhiv, M.

    1999-01-01

    The investigated heterostructures were grown by molecular beam technology of thin lead sulphide films on monocrystalline ZnSe substrates of (110) orientation. Electrical investigations performed immediately after samples preparation finishing have found that these heterostructures are abrupt heterojunctions photosensitive at T=77K in 2/5 μm wave length region. The examination of long-term (3-4 years) stability of this characteristic has shown the change of photosensitivity range to 0.40/1.12 μm at 300 K. Such a phenomena can be explained by the formation of PbO PbSO 4 complexes on intercrystalline boundaries of lead sulphide film surface with corresponding changes in the space charge region of n-PbS/n-ZnSe heterojunction

  8. Optical properties of CdS and CdS/ZnS quantum dots synthesized by reverse micelle method

    International Nuclear Information System (INIS)

    Vu Thi Kim Lien; Chu Viet Ha; Le Tien Ha; Nguyen Nhu Dat

    2009-01-01

    The CdS and CdS/ZnS semiconductor quantum dots have been synthesized by reverse micelle method using sodium bis (2-ethylhexyl) sulfosuccinate (AOT) surfactant agent. The quantum dot diameter is about 2.5 to 4 nm depending on the concentration of the surfactant agent. It is interesting that, in contrast to other colloidal methods, the size of quantum dots does not depend on the growth time. The absorption spectra of CdS quantum dots show the narrow size distribution. The photoluminescence (PL) spectra include two bands, the intrinsic emission of CdS nanocrystals and the emission of surface states. There is noticeable increase of the PL intensity and subsequent photostability of CdS/ZnS core-shell quantum dots in comparison with CdS quantum dots without the ZnS shell.

  9. 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. Copyright © 2016 Elsevier Ltd. All rights reserved.

  10. Determination of Cd, Pb and Cu in Mandovi estuary by differential pulse anodic stripping voltammetry

    Digital Repository Service at National Institute of Oceanography (India)

    George, M.D.; Sawkar, K.; Reddy, C.V.G.

    Dissolved labile and non-labile (organically associated) concentration of Cd, Pb and Cu in Mandovi Estuary, Goa, India have been measured for 1 y (February 1980 to January 1981). Percentage non-labile form varies from 0-50% of the total for Cd, from...

  11. Distribution of various forms of Cd, Pb and Cu in the Wadge Bank region (Arabian Sea)

    Digital Repository Service at National Institute of Oceanography (India)

    George, M.D.

    Labile, nonlabile and particulate forms of Cd,Pb and Cu were determined in 29 water samples collected from a depth of 5 m, from the Wadge Bank area. Labile Cd varied from 0.1 to 0.2 mu g.l-1 while nonlabile fraction was in the range 0.1 to 0.3 mu gl...

  12. Performance updating of CdZnTe strip-drift detectors

    DEFF Research Database (Denmark)

    Shorohov, M.; Tsirkunova, I.; Loupilov, A.

    2007-01-01

    59.6 and 662 keV correspondingly. Recently, significant progress was done in CdZnTe crystals growth technology. In the present paper we present preliminary result of performance updating of CdZnTe strip-drift detectors based on crystal of 10 x 10 x 6 mm 3 produced by Yinnel Tech company. Results...

  13. Synthesis and characterization of Sn-doped CdZnS nanoparticles

    Indian Academy of Sciences (India)

    Administrator

    Abstract. Tin (Sn)-doped cadmium zinc sulphide nanoparticles (CdZnS : Sn) were synthesized by the chemi- cal 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 ...

  14. Synthesis and characterization of Sn-doped CdZnS nanoparticles

    Indian Academy of Sciences (India)

    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 ...

  15. TELAAHAN LOGAM BERAT Pb DAN Cd PADA SEDIMEN DI PERAIRAN BARAT LAUT DUMAI – RIAU

    Directory of Open Access Journals (Sweden)

    Syahminan Syahminan

    2015-08-01

    Full Text Available This research was conducted in Dumai sea western waters, Riau Province. Dumai marine waters are part of the territorial waters of Riau that relate directly to the Strait of Malacca, and are at Rupat Strait region, and has a high accessibility of the region, both locally and internationally. Dumai waters is also an estuary waters affected by the activities of the land, and the waters that receive input from various types of waste from various activities in Dumai city and surrounding areas. The research was aimed to knowing the general condition of the Dumai sea western waters, analyzing the content of Pb and Cd in sediments, observing the correlation between organic matter and heavy metal of Pb and Cd, and find out the status of pollution Dumai Sea Western Waters by comparing the results of the analysis with some quality standard countries, The method used is a survey method. Based on the Decree of The Minister of Environment No. 51 of 2004, that the general condition of the Dumai sea western waters still can support the life activities of marine organisms in the waters. The results showed that the concentrations of Pb and Cd in sediments of Dumai is below the threshold value. The results of simple linear regression analysis of heavy metals Pb and Cd with organic matter content showed that the concentration of heavy metals Pb and Cd is not influenced by organic matter content or have a very weak correlation with linear regression equation consecutive y = 0,0834x + 7,7866 and y = -0,001x + 0,0559. The status of pollution of Dumai sea western waters for Pb 8,76 µg/g and Cd 0,04 µg/g still under quality standardsKeywords: Dumai Sea Western Waters, Sediments, Heavy Metal Pb and Cd

  16. Rapid adsorption of Pb, Cu and Cd from aqueous solutions by β-cyclodextrin polymers

    Science.gov (United States)

    He, Junyong; Li, Yulian; Wang, Chengming; Zhang, Kaisheng; Lin, Dongyue; Kong, Lingtao; Liu, Jinhuai

    2017-12-01

    Removing heavy metals from aqueous solutions has drawn more and more attentions these years because of their serious global health challenge to human society. To develop an adsorbent with low-cost and high-efficiency for removal of heavy metals (HMs), β-cyclodextrin (β-CD) polymers crosslinked with rigid aromatic groups were prepared and used for lead (Pb), copper (Cu) and cadmium (Cd) removal for the first time. The negatively charged β-CD polymers with large BET surface area were suitable to be used in HMs adsorption. The adsorption process completed in 5 min was well fit by Freundlich isotherm model and pseudo-second-order model. The intraparticle diffusion model was also appropriate to describe the adsorption of Pb, Cu and Cd on β-CD polymer. The maximum of adsorption capacities at 25 °C for Pb, Cu and Cd were 196.42, 164.43 and 136.43 mg/g when the initial concentration was 200 mg/L. The HMs adsorption process on the surface of β-CD polymer was an endothermic and spontaneous process. Both of the electrostatic interaction and distribution of Pb, Cu and Cd species influenced the adsorption process at different pH values. The order of removal efficiencies in multi-component adsorption for the three metal ions were Pb > Cu > Cd. The adsorption mechanisms were H+ ions on hydroxyl groups exchanged with heavy metal ions and electrostatic interactions. This study indicated that β-CD polymers could be developed into effective adsorbents for rapid removal of heavy metals.

  17. Synthesis and Structural Studies of Nanocrystalline Cd 0.3 Zn 0.7 Fe ...

    African Journals Online (AJOL)

    Synthesis and Structural Studies of Nanocrystalline Cd 0.3 Zn 0.7 Fe 2 O 4. ... South African Journal of Chemistry ... The synthesis of Cd0.3Zn0.7Fe2O4 nanoparticles has been achieved by a simple thermal decomposition method from the inorganic precursor, Cdd0.3Zn0.7Fe2(cin)3(N2H4)2, which was obtained by a novel ...

  18. CdS/ZnS nanocomposites: from mechanochemical synthesis to cytotoxicity issues

    Energy Technology Data Exchange (ETDEWEB)

    Baláž, Peter; Baláž, Matej [Institute of Geotechnics, Slovak Academy of Sciences, 04001 Košice (Slovakia); Dutková, Erika, E-mail: dutkova@saske.sk [Institute of Geotechnics, Slovak Academy of Sciences, 04001 Košice (Slovakia); Zorkovská, Anna [Institute of Geotechnics, Slovak Academy of Sciences, 04001 Košice (Slovakia); Kováč, Jaroslav; Hronec, Pavol; Kováč, Jaroslav [Institute of Electronics and Photonics, Slovak University of Technology and International Laser Centre, 81219 Bratislava (Slovakia); Čaplovičová, Mária [STU Centre for Nanodiagnostics, Slovak University of Technology, Vazovova 5, 812 43 Bratislava (Slovakia); Mojžiš, Ján; Mojžišová, Gabriela [Faculty of Medicine, P. J. Šafárik University, 04011 Košice (Slovakia); Eliyas, Alexander; Kostova, Nina G. [Institute of Catalysis, Bulgarian Academy of Sciences, 1113 Sofia (Bulgaria)

    2016-01-01

    CdS/ZnS nanocomposites have been prepared by a two-step solid-state mechanochemical synthesis. CdS has been prepared from cadmium acetate and sodium sulfide precursors in the first step. The obtained cubic CdS (hawleyite, JCPDS 00-010-0454) was then mixed in the second step with the cubic ZnS (sphalerite, JCPDS 00-005-0566) synthesized mechanochemically from the analogous precursors. The crystallite sizes of the new type CdS/ZnS nanocomposite, calculated based on the XRD data, were 3–4 nm for both phases. The synthesized nanoparticles have been further characterized by high-resolution transmission electron microscopy (HRTEM) and micro-photoluminescence (μPL) spectroscopy. The PL emission peaks in the PL spectra are attributed to the recombination of holes/electrons in the nanocomposites occurring in depth associated with Cd, Zn vacancies and S interstitials. Their photocatalytic activity was also measured. In the photocatalytic activity tests to decolorize Methyl Orange dye aqueous solution, the process is faster and its effectivity is higher when using CdS/ZnS nanocomposite, compared to single phase CdS. Very low cytotoxic activity (high viability) of the cancer cell lines (selected as models of living cells) has been evidenced for CdS/ZnS in comparison with CdS alone. This fact is in a close relationship with Cd(II) ions dissolution tested in a physiological solution. The concentration of cadmium dissolved from CdS/ZnS nanocomposites with variable Cd:Zn ratio was 2.5–5.0 μg.mL{sup −1}, whereas the concentration for pure CdS was much higher — 53 μg.ml{sup −1}. The presence of ZnS in the nanocrystalline composite strongly reduced the release of cadmium into the physiological solution, which simulated the environment in the human body. The obtained CdS/ZnS quantum dots can serve as labeling media and co-agents in future anti-cancer drugs, because of their potential in theranostic applications. - Highlights: • CdS/ZnS nanocomposites with crystallite

  19. Prospects of Ternary Cd1-x Zn x S as an Electron Transport Layer and Associated Interface Defects in a Planar Lead Halide Perovskite Solar Cell via Numerical Simulation

    Science.gov (United States)

    Chowdhury, Towhid Hossain; Ferdaous, Mohammad Tanvirul; Wadi, Mohd. Aizat Abdul; Chelvanathan, Puvaneswaran; Amin, Nowshad; Islam, Ashraful; Kamaruddin, Nurhafiza; Zin, Muhammad Irsyamuddin M.; Ruslan, Mohd Hafidz; Sopian, Kamaruzzaman Bin; Akhtaruzzaman, Md.

    2018-03-01

    In this study we present a ternary alloy, Cd1-x Zn x S as an electron transport layer for a planar lead halide perovskite solar cell via numerical simulation with solar cell capacitance simulator (SCAPS) software. Performance dependence on molar composition variation in the Cd1-x Zn x S alloy was studied for the mixed perovskite CH3NH3PbI3-x Cl x absorber and spiro-OMeTAD hole transport material in a planar perovskite solar cell. Additionally, the defects on both Cd1-x Zn x S/CH3NH3PbI3-x Cl x and CH3NH3PbI3-x Cl x /spiro-OMeTAD interface were thoroughly investigated. Simultaneously, a thickness of 700 nm for CH3NH3PbI3-x Cl x absorber with 50-nm-thick Cd0.2Zn0.8S (x = 0.8) was optimized. Analysis of the numerical solutions via SCAPS provides a trend and pattern for Cd0.2Zn0.8S as an effective electron transport layer for planar perovskite solar cells with a yield efficiency up to 24.83%. The planar perovskite solar cell shows an open-circuit voltage of 1.224 V, short-circuit current density of 25.283 mA/cm2 and a fill factor of 80.22.

  20. Stabilization of lead (Pb) and zinc (Zn) in contaminated rice paddy soil using starfish: A preliminary study.

    Science.gov (United States)

    Moon, Deok Hyun; Hwang, Inseong; Koutsospyros, Agamemnon; Cheong, Kyung Hoon; Ok, Yong Sik; Ji, Won Hyun; Park, Jeong-Hun

    2018-05-01

    Lead (Pb) and zinc (Zn) contaminated rice paddy soil was stabilized using natural (NSF) and calcined starfish (CSF). Contaminated soil was treated with NSF in the range of 0-10 wt% and CSF in the range of 0-5 wt% and cured for 28 days. Toxicity characteristic leaching procedure (TCLP) test was used to evaluate effectiveness of starfish treatment. Scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX) analyses were conducted to investigate the mechanism responsible for effective immobilization of Pb and Zn. Experimental results suggest that NSF and CSF treatments effectively immobilize Pb and Zn in treated rice paddy soil. TCLP levels for Pb and Zn were reduced with increasing NSF and CSF dosage. Comparison of the two treatment methods reveals that CSF treatment is more effective than NSF treatment. Leachability of the two metals is reduced approximately 58% for Pb and 51% for Zn, upon 10 wt% NSF treatment. More pronounced leachability reductions, 93% for Pb and 76% for Zn, are achieved upon treatment with 5 wt% CSF. Sequential extraction results reveal that NSF and CSF treatments of contaminated soil generated decrease in exchangeable/weak acid Pb and Zn soluble fractions, and increase of residual Pb and Zn fractions. Results for the SEM-EDX sample treated with 5 wt% CSF indicate that effective Pb and Zn immobilization is most probably associated with calcium silicate hydrates (CSHs) and calcium aluminum hydrates (CAHs). Copyright © 2018 Elsevier Ltd. All rights reserved.

  1. X-ray fluorescence analysis of Pb, Fe and Zn in kohl

    Directory of Open Access Journals (Sweden)

    Eman Daar

    Full Text Available Kohl, a facial salve used in ancient times as a symbol of affluence, now enjoys more widespread traditional followings, for cosmetic, religious and supposed medicinal purposes. Popularly used by women and men of all ages, particularly those of North African, Middle Eastern, Southern Asia, Japanese and Chinese origins, it is also known to be used on neonates and children from such populations. With small-scale producers of kohl possessing a growing awareness of the adverse market impact of products that contain (lead Pb and other toxicity related elements, some claim their products to be Pb-free, offering an apparent change from the more traditional galena-based (lead sulphide media. Among the published physiological effects of exposure to Pb is that it replaces Ca in bones and teeth, making them weak and fragile, other impacts including nephrotoxicity, also linked with increased Pb blood levels in studies in Oman, Canada, Saudi Arabia, India and Pakistan. Current study involves XRF analysis of Pb, Fe and Zn concentrations in 135 samples of kohl from nine randomly selected suppliers (15 samples of each brand being represented. In pursuit of this, use was made of an in-house assembled facility comprising compact high-performance components, the arrangement offering sufficient sensitivity for the purposes of present study. In most of the samples investigated in the present study observation has been made of concentrations of Pb at elevated levels, quantification of those levels also demonstrating a need to address self-attenuation by the Pb itself. Significant concentration of Fe have also been found in several of the samples. Keywords: X-ray florescence, Pb, Fe and Zn contamination, Kohl

  2. Use of cattails in treating wastewater from a Pb/Zn mine

    Science.gov (United States)

    Lan, Chongyu; Chen, Guizhu; Li, Liuchun; Wong, M. H.

    1992-01-01

    This article describes the use of a combined treatment system, which includes an aquatic treatment pond with Typha latifolia Linn. (Typhaceae) as the dominant species and a stabilization pond, to treat the wastewater from a Pn/Zn mine at Shaoguan, Guangdong Province, China. In 1983, it was noted that T. latifolia bloomed in areas affected by the wastewater emitted from the mine, hence a combined purification system was subsequently built. The influent contained high levels of total suspended solids (4635 mg/liter), chemical oxygen demand (14.5 mg/liter) as well as Pb (1.6 mg/liter) and Zn (1.9 mg/liter). The results of the effluent after treatment showed that the total suspended solids, chemical oxygen demand, Pb, and Zn had been reduced by 99%, 55%, 95%, and 80% respectively. The results of plant tissue analysis indicled that T. latifolia assimilated significant amounts of Pb and Zn, especially in the root portion. During 1986 several species of algae and fish were present in the pond, usually with a higher density in areas containing lower metal concentrations in the water.

  3. 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 pHPHREEQC equilibrium modeling, the leaching of major ions and trace metals was mainly controlled by the dissolution/precipitation and surface complexation reactions, respectively. A 1-D reactive transport experiment was undertaken to better understand how 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. Copyright © 2014 Elsevier B.V. All rights reserved.

  4. Bio-remediation of Pb and Cd polluted soils by switchgrass: A case study in India.

    Science.gov (United States)

    Arora, Kalpana; Sharma, Satyawati; Monti, Andrea

    2016-01-01

    In the present study bioremediation potential of a high biomass yielding grass, Panicum virgatum (switchgrass), along with plant associated microbes (AM fungi and Azospirillum), was tested against lead and cadmium in pot trials. A pot trial was set up in order to evaluate bioremediation efficiency of P. virgatum in association with PAMs (Plant Associated Microbes). Growth parameters and bioremediation potential of endomycorrhizal fungi (AMF) and Azospirillum against different concentrations of Pb and Cd were compared. AM fungi and Azospirillum increased the root length, branches, surface area, and root and shoot biomass. The soil pH was found towards neutral with AMF and Azospirillum inoculations. The bioconcentration factor (BCF) for Pb (12 mg kg(-1)) and Cd (10 mg kg(-1)) were found to be 0.25 and 0.23 respectively and translocation index (Ti) was 17.8 and 16.7 respectively (approx 45% higher than control). The lower values of BCF and Ti, even at highest concentration of Pb and Cd, revealed the capability of switchgrass of accumulating high concentration of Pb and Cd in the roots, while preventing the translocation of Pb and Cd to aerial biomass.

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

    Indian Academy of Sciences (India)

    Abstract. 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 ...

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

    Indian Academy of Sciences (India)

    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 ...

  7. Use of radiometric indices to evaluate Zn and Pb stress in two grass species (Festuca rubra L. and Vulpia myuros L.).

    Science.gov (United States)

    Gómez, J; Yunta, F; Esteban, E; Carpena, R O; Zornoza, P

    2016-11-01

    Vegetation indices obtained from radiometric measurements have been used to estimate the stress response of plants grown in contaminated sites. The phytotoxicity of Pb and Zn in Festuca rubra L. and Vulpia myuros L. plants grown under hydroponic conditions was evaluated using vegetation indices obtained from radiometric measurements. The plants were supplied with 3 mM Zn (+Zn), 500 μM Pb (+Pb) and 500 μM Pb with EDTA (+PbEDTA) for 3 months. Significantly higher Zn concentrations in F. rubra shoots compared with V. myuros shoots were detected for Zn and Pb treatments. EDTA increased Pb transport to the shoots for both grasses, while Pb-treated plants retained Pb primarily in the roots. All vegetation indices tested showed the highest differences in F. rubra under +PbEDTA treatment and minor effects under +Zn, whereas the major variations for V. myuros corresponded to +Zn treatment, followed by +PbEDTA. Red edge normalized difference vegetation index, yellowness index and anthocyanin concentration index were the most sensitive indices to report Zn and Pb phytotoxicity in these grasses. According to the results obtained, both metal concentrations and radiometric indices suggested that Pb is more phytotoxic to F. rubra, which tolerates high Zn levels, whereas V. myuros was strongly affected by high Zn levels and markedly tolerant to Pb, even when applied in a mobile form (PbEDTA). Both species could be used in the phytostabilization of Zn- and Pb-contaminated soils. The abilities of F. rubra to accumulate Zn and V. myuros to accumulate Pb in the roots would facilitate a more efficient phytoremediation strategy when used in combination.

  8. Performance optimization of CdTe and CdZnTe detectors for γ-spectrometry

    International Nuclear Information System (INIS)

    Montemont, Guillaume

    2000-01-01

    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) [fr

  9. 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...

  10. Ice-core based assessment of historical anthropogenic heavy metal (Cd, Cu, Sb, Zn) emissions in the Soviet Union.

    Science.gov (United States)

    Eichler, Anja; Tobler, Leonhard; Eyrikh, Stella; Malygina, Natalia; Papina, Tatyana; Schwikowski, Margit

    2014-01-01

    The development of strategies and policies aiming at the reduction of environmental exposure to air pollution requires the assessment of historical emissions. Although anthropogenic emissions from the extended territory of the Soviet Union (SU) considerably influenced concentrations of heavy metals in the Northern Hemisphere, Pb is the only metal with long-term historical emission estimates for this region available, whereas for selected other metals only single values exist. Here we present the first study assessing long-term Cd, Cu, Sb, and Zn emissions in the SU during the period 1935-1991 based on ice-core concentration records from Belukha glacier in the Siberian Altai and emission data from 12 regions in the SU for the year 1980. We show that Zn primarily emitted from the Zn production in Ust-Kamenogorsk (East Kazakhstan) dominated the SU heavy metal emission. Cd, Sb, Zn (Cu) emissions increased between 1935 and the 1970s (1980s) due to expanded non-ferrous metal production. Emissions of the four metals in the beginning of the 1990s were as low as in the 1950s, which we attribute to the economic downturn in industry, changes in technology for an increasing metal recovery from ores, the replacement of coal and oil by gas, and air pollution control.

  11. SORPTION-DESORPTION MECHANISM OF Zn(II AND Cd(II ON CHITIN

    Directory of Open Access Journals (Sweden)

    Sri Juari Santosa

    2010-06-01

    Full Text Available This study reports the results of the elucidation of the sorption-desorption mechanism of Zn(II and Cd(II on chitin through the determination of capacity, energy, and rate constant of sorption as well as the investigation of their desorption properties in NaCl and Na2EDTA solutions. The chitin was isolated through deproteination followed by demineralization of crab (Portunus pelagicus Linn shell using NaOH solutions. The sorption of both metal ions followed the Langmuir isotherm model, resulting the sorption capacities of 3.2 x 10-4 and 2.8 x 10-4 mol g-1 for Zn(II and Cd(II, respectively, and sorption energies of 15.1 kJ mol-1 for Zn(II and 17.9 kJ mol-1 for Cd(II. It was also observed that Zn(II was sorbed slightly faster than Cd(II with first order sorption rate constants of 2.82 x 10-3 min-1 for Zn(II and 2.61 x 10-3 min-1 for Cd(II. The result of the desorption experiment showed that Cd(II and especially Zn(II could only be exchanged by Na(I after desorbing those metal ions by strong chelating agent of EDTA2-. The easier desorption of Zn(II than Cd(II by EDTA2- must be attributed by the smaller sorption energy of Zn(II and by harder acid property of Zn(II than Cd(II as EDTA2- contained hard electron donor elements.   Keywords: sorption, desorption, chitin, Zn(II, Cd(II

  12. Composition and strain effects in Type I and Type II heterostructure ZnSe/Cd(Zn)S and ZnSe/Cd1-xZnxS core/shell quantum dots

    Science.gov (United States)

    Gheshlaghi, Negar; Pisheh, Hadi Sedaghat; Ünlü, Hilmi

    2017-11-01

    We investigated the effect of ternary shell alloy composition on the bandgap and diameter of core of ZnSe / Cd1 - x Znx S heterostructure core/shell quantum dots, which were synthesized by using a simple colloidal technique. Characterization by using the x-ray diffraction (XRD), transmission electron microscopy (TEM), UV-Vis absorption and fluorescence emission spectroscopic techniques indicate that (i) there is a transition of ZnSe / Cd0.6 Zn0.4 S Type-I heterostructure (electrons and holes tend to localize in core) to ZnSe / Cd0.75 Zn0.25 S quasi-Type-II heterostructures (holes tend to localized in the core and electrons are delocalized) and (ii) then after large red shift and Stock-shift in PL emission spectra but not a distinct absorption peak in UV spectra become noticeable in ZnSe/Cd0.75Zn0.25 S quasi-Type II and ZnSe/CdS Type II heterostructures (electrons are localized in core and holes are localized in shell). Furthermore, the increase of Cd:S ratio in shell alloy composition shifts the XRD peaks to lower 2θ degrees which corresponds to tensile strain in the ZnSe core. Finally, the hydrostatic interfacial strain has effect on the squeezing or stretching the capped core: A decrease of compressive force on core from ZnSe/ZnS to tensile force in ZnSe/CdS with increase in Cd:S ratio indicates that transition of compressive strain to tensile strain takes place with the transition from Type-I to II heterostructure.

  13. 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...

  14. Highly luminescent CdSe/ZnSe core-shell quantum dots of one-pot preparation in octadecene

    NARCIS (Netherlands)

    Zeng, Q.; Kong, X.; Zhang, Y.; Zhang, H.

    2008-01-01

    CdSe/ZnSe core-shell quantum dots were synthesized using a new one-pot procedure where the core was prepared in octadecene. A ZnSe shell around a CdSe nanoparticle was formed by the reaction of selenium-richness on the surfaces of CdSe nanoparticles with Zn2+ from the injected zinc stearate

  15. 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)

    Ouda, S.M.

    2010-01-01

    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 Co 2+ , Cd 2+ and Pb 2+ 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)

  16. Cd and Zn interactions and toxicity in ectomycorrhizal basidiomycetes in axenic culture

    Directory of Open Access Journals (Sweden)

    Vinicius H. De Oliveira

    2018-03-01

    Full Text Available Background Metal contamination in soils affects both above- and belowground communities, including soil microorganisms. Ectomycorrhizal (ECM fungi are an important component in belowground community and tolerant strains have great potential in enhancing plant-based remediation techniques. We assessed cadmium and zinc toxicity in five ECM species in liquid media (Hebeloma subsaponaceum; H. cylindrosporum; H. crustuliniforme; Scleroderma sp.; Austroboletus occidentalis and investigated the potential of Zn to alleviate Cd toxicity. Due to highly divergent results reported in the literature, liquid and solid media were compared experimentally for the first time in terms of differential toxicity thresholds in Cd and Zn interactions. Methods A wide range of Cd and Zn concentrations were applied to ectomycorrhizal fungi in axenic cultures (in mg L−1: 0; 1; 3; 9; 27; 81; 243 for the Cd treatments, and 0; 1; 30; 90; 270; 810; 2,430 for Zn. Combined Zn and Cd treatments were also applied to H. subsaponaceum and Scleroderma sp. Dry weight was recorded after 30 days, and in case of solid medium treatments, radial growth was also measured. Results and Discussion All species were adversely affected by high levels of Cd and Zn, and A. occidentalis was the most sensitive, with considerable biomass decrease at 1 mg L−1 Cd, while Scleroderma sp. and H. subsaponaceum were the most tolerant, which are species commonly found in highly contaminated sites. Cd was generally 10 times more toxic than Zn, which may explain why Zn had little impact in alleviating Cd effects. In some cases, Cd and Zn interactions led to a synergistic toxicity, depending on the concentrations applied and type of media used. Increased tolerance patterns were detected in fungi grown in solid medium and may be the cause of divergent toxicity thresholds found in the literature. Furthermore, solid medium allows measuring radial growth/mycelial density as endpoints which are informative and in

  17. Phosphine-free synthesis of high-quality reverse type-I ZnSe/CdSe core with CdS/Cd(x)Zn(1 - x)S/ZnS multishell nanocrystals and their application for detection of human hepatitis B surface antigen.

    Science.gov (United States)

    Shen, Huaibin; Yuan, Hang; Niu, Jin Zhong; Xu, Shasha; Zhou, Changhua; Ma, Lan; Li, Lin Song

    2011-09-16

    Highly photoluminescent (PL) reverse type-I ZnSe/CdSe nanocrystals (NCs) and ZnSe/CdSe/CdS/Cd(x)Zn(1 - x)S/ZnS core/multishell NCs were successfully synthesized by a phosphine-free method. By this low-cost, 'green' synthesis route, more than 10 g of high-quality ZnSe/CdSe/CdS/Cd(x)Zn(1 - x)S/ZnS NCs were synthesized in a large scale synthesis. After the overgrowth of a CdS/Cd(x)Zn(1 - x)S/ZnS multishell on ZnSe/CdSe cores, the PL quantum yields (QYs) increased from 28% to 75% along with the stability improvement. An amphiphilic oligomer was used as a surface coating agent to conduct a phase transfer experiment, core/multishell NCs were dissolved in water by such surface modification and the QYs were still kept above 70%. The as-prepared water dispersible ZnSe/CdSe/CdS/Cd(x)Zn(1 - x)S/ZnS core/multishell NCs not only have high fluorescence QYs but also are extremely stable in various physiological conditions. Furthermore, a biosensor system (lateral flow immunoassay system, LFIA) for the detection of human hepatitis B surface antigen (HBsAg) was developed by using this water-soluble core/multishell NCs as a fluorescent label and a nitrocellulose filter membrane for lateral flow. The result showed that such ZnSe/CdSe/CdS/Cd(x)Zn(1 - x)S/ZnS core/multishell NCs were excellent fluorescent labels to detect HBsAg. The sensitivity of HBsAg detection could reach as high as 0.05 ng ml( - 1).

  18. Phosphine-free synthesis of high-quality reverse type-I ZnSe/CdSe core with CdS/Cd{sub x}Zn{sub 1-x}S/ZnS multishell nanocrystals and their application for detection of human hepatitis B surface antigen

    Energy Technology Data Exchange (ETDEWEB)

    Shen Huaibin; Niu Jin Zhong; Xu Shasha; Zhou Changhua; Li Linsong [Key Laboratory for Special Functional Materials, Henan University, Kaifeng 475004 (China); Yuan Hang; Ma Lan, E-mail: malan@sz.tsinghua.edu.cn, E-mail: lsli@henu.edu.cn [Life Science Division, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055 (China)

    2011-09-16

    Highly photoluminescent (PL) reverse type-I ZnSe/CdSe nanocrystals (NCs) and ZnSe/CdSe/CdS/Cd{sub x}Zn{sub 1-x}S/ZnS core/multishell NCs were successfully synthesized by a phosphine-free method. By this low-cost, 'green' synthesis route, more than 10 g of high-quality ZnSe/CdSe/CdS/Cd{sub x}Zn{sub 1-x}S/ZnS NCs were synthesized in a large scale synthesis. After the overgrowth of a CdS/Cd{sub x}Zn{sub 1-x}S/ZnS multishell on ZnSe/CdSe cores, the PL quantum yields (QYs) increased from 28% to 75% along with the stability improvement. An amphiphilic oligomer was used as a surface coating agent to conduct a phase transfer experiment, core/multishell NCs were dissolved in water by such surface modification and the QYs were still kept above 70%. The as-prepared water dispersible ZnSe/CdSe/CdS/Cd{sub x}Zn{sub 1-x}S/ZnS core/multishell NCs not only have high fluorescence QYs but also are extremely stable in various physiological conditions. Furthermore, a biosensor system (lateral flow immunoassay system, LFIA) for the detection of human hepatitis B surface antigen (HBsAg) was developed by using this water-soluble core/multishell NCs as a fluorescent label and a nitrocellulose filter membrane for lateral flow. The result showed that such ZnSe/CdSe/CdS/Cd{sub x}Zn{sub 1-x}S/ZnS core/multishell NCs were excellent fluorescent labels to detect HBsAg. The sensitivity of HBsAg detection could reach as high as 0.05 ng ml{sup -1}.

  19. Surface passivation of HgCdTe by CdZnTe and its characteristics

    Science.gov (United States)

    Lee, T. S.; Choi, K. K.; Jeoung, Y. T.; Kim, H. K.; Kim, J. M.; Kim, Y. H.; Chang, J. M.; Song, W. S.; Kim, S. U.; Park, M. J.; Lee, S. D.

    1997-06-01

    In this paper, we report the results of capacitance-voltage measurements conducted on several metal-insulator semiconductor (MIS) capacitors in which HgCdTe surfaces are treated with various surface etching and oxidation processes. CdZnTe passivation layers were deposited on HgCdTe surfaces by thermal evaporation after the surfaces were etched with 0.5-2.0% bromine in methanol solution, or thin oxide layers (tox ˜ few ten Å) were grown on the surfaces, in order to investigate effects of the surface treatments on the electrical properties of the surfaces, as determined from capacitance-voltage (C-V) measurements at 80K and 1 MHz. A negative flat band voltage has been observed for MIS capacitors fabricated after etching of HgCdTe surfaces with bromine in methanol solutions, which is reported to make the surface Te-rich. It is inferred that residual Te on the surface is a positive charge, Te4+. C-V characteristics for MIS capacitors fabricated on oxide surfaces grown by air-exposure and electrolytic process have shown large hysteresis effects, from which it is inferred that imperfect and electrically active oxide compounds and HgTe particles near the surface become slow interface states.

  20. Nanostructure CdS/ZnO heterojunction configuration for photocatalytic degradation of Methylene blue

    Science.gov (United States)

    Velanganni, S.; Pravinraj, S.; Immanuel, P.; Thiruneelakandan, R.

    2018-04-01

    In the present manuscript, thin films of Zinc Oxide (ZnO) have been deposited on a FTO substrate using a simple successive ionic layer adsorption and reaction (SILAR) and chemical bath deposition (CBD) method. Cadmium Sulphide (CdS) nanoparticles are sensitized over ZnO thin films using SILAR method. The synthesized nanostructured CdS/ZnO heterojunction thin films was characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), High resolution transmission electron microscopy (HR-TEM), X-ray photoelectron spectroscopy (XPS), UV-Vis spectroscopy and Raman spectroscopy techniques. The band gap of CdS nanoparticles over ZnO nanostructure was found to be about 3.20 eV. The photocatalytic activities of the deposited CdS/ZnO thin films were evaluated by the degradation of methylene blue (MB) in an aqueous solution under sun light irradiation.

  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.

  2. Origin and tectonic implications of the Zhaxikang Pb-Zn-Sb-Ag deposit in northern Himalaya: evidence from structures, Re-Os-Pb-S isotopes, and fluid inclusions

    Science.gov (United States)

    Zhou, Qing; Li, Wenchang; Qing, Chengshi; Lai, Yang; Li, Yingxu; Liao, Zhenwen; Wu, Jianyang; Wang, Shengwei; Dong, Lei; Tian, Enyuan

    2018-04-01

    The Zhaxikang Pb-Zn-Sb-Ag-(Au) deposits, located in the eastern part of northern Himalaya, totally contain more than 1.146 million tonnes (Mt) of Pb, 1.407 Mt of Zn, 0.345 Mt of Sb, and 3 kilotonnes (kt) of Ag. Our field observations suggest that these deposits are controlled by N-S trending and west- and steep-dipping normal faults, suggesting a hydrothermal rather than a syngenetic sedimentary origin. The Pb-Zn-Sb-Ag-(Cu-Au) mineralization formed in the Eocene as indicated by a Re-Os isochron age of 43.1 ± 2.5 Ma. Sulfide minerals have varying initial Pb isotopic compositions, with (206Pb/204Pb)i of 19.04-19.68, (207Pb/204Pb)i of 15.75-15.88, and (208Pb/204Pb)i of 39.66-40.31. Sulfur isotopic values display a narrow δ34S interval of +7.8-+12.2‰. These Pb-S isotopic data suggest that the Zhaxikang sources of Pb and S should be mainly from the coeval felsic magmas and partly from the surrounding Mesozoic strata including metasedimentary rocks and layered felsic volcanic rocks. Fluid inclusion studies indicate that the hydrothermal fluids have medium temperatures (200-336 °C) but varying salinities (1.40-18.25 wt.% NaCl equiv.) with densities of 0.75-0.95 g/cm3, possibly suggesting an evolution mixing between a high salinity fluid, perhaps of magmatic origin, with meteoric water.

  3. REHABILITASI TANAH SAWAH TERCEMAR LOGAM BERAT Pb DAN Cd MELALUI FITOREMEDIASI

    Directory of Open Access Journals (Sweden)

    Sandra Sukmaning Adji

    2016-09-01

    Full Text Available It is indicated that rice field soil and plants on Rancaekek Bandung is containing heavy metal elements. This research aims to find out rehabilitation method for rice field soil by phytoremediation. Experiment was conducted in greenhouse. Vegetation used for this research were eceng gondok, mendong, akar wangi and haramay. The vegetation treatment was conducted under greenhouse experiments using Complete Randomized Design (CRD. Result showed that the use of vegetation had reduced the volume of Pb and Cd in the soil. Heavy metals are also contained within the roots and the leaves of the indicator plants. Mendong contained the highest concentration of Pb accumulated in its root, while akar wangi was indicated as contained Cd in its roots. Eceng gondok was indicated as containing the highest consentration of Pb and Cd accumulated in its leaves

  4. Uptake pathways and toxicity of Cd and Zn in the earthworm Eisenia fetida.

    NARCIS (Netherlands)

    Li, L.-Z.; Zhou, D.-M.; Peijnenburg, W.J.G.M.; Wang, P.; van Gestel, C.A.M.; Jin, S.-Y.; Wang, Q.-Y.

    2010-01-01

    The uptake of Cd and Zn by the earthworm Eisenia fetida was determined at varying Ca concentrations and with pre-exposure to different metabolic inhibitors in simulated soil solutions over a 48-h period. The presence of Ca in the solution had complex actions on Cd uptake. At a low Cd concentration

  5. Synthesis and characterization of highly luminescent CdSe-core CdS/Zn0.5Cd0.5S/ZnS multishell nanocrystals.

    Science.gov (United States)

    Xie, Renguo; Kolb, Ute; Li, Jixue; Basché, Thomas; Mews, Alf

    2005-05-25

    We report on the preparation and structural characterization of CdSe nanocrystals, which are covered by a multishell structure from CdS and ZnS. By using the newly developed successive ion layer adhesion and reaction (SILAR) technique, we could gradually change the shell composition from CdS to ZnS in the radial direction. Because of the stepwise adjustment of the lattice parameters in the radial direction, the resulting nanocrystals show a high crystallinity and are almost perfectly spherical, as was investigated by X-ray diffraction and electron microscopy. Also, due to the radial increase of the respective valence- and conduction-band offsets, the nanocrystals are well electronically passivated. This leads to a high fluorescence quantum yield of 70-85% for the amine terminated multishell particles in organic solvents and a quantum yield of up to 50% for mercapto propionic acid-covered particles in water. Finally, we present experimental results that substantiate the superior photochemical and colloidal stability of the multishell particles.

  6. Study of the potential of barnyard grass for the remediation of Cd- and Pb-contaminated soil.

    Science.gov (United States)

    Xu, Jianling; Cai, Qiongyao; Wang, Hanxi; Liu, Xuejun; Lv, Jing; Yao, Difu; Lu, Yue; Li, Wei; Liu, Yuanyuan

    2017-05-01

    In this study, the microwave digestion method was used to determine total cadmium (Cd) and lead (Pb) concentrations, the BCR method was used to determine different states of Cd and Pb, and atomic absorption spectroscopy (AAS) and inductively coupled plasma optical emission spectrometry (ICP-OES) were used to determine Cd and Pb concentrations in simulated soil and barnyard grass before and after planting barnyard grass to provide a theoretical basis for the remediation of Cd- and Pb-contaminated soil. The results showed that the bioconcentration factor changes with different Cd concentrations are relatively complex and that the removal rate increases regularly. The 100 mg kg -1 Cd treatment had the highest removal rate, which reached 36.66%. For Pb, the bioconcentration factor decreased and tended to reach equilibrium as the Pb concentration increased. The highest removal rate was 41.72% and occurred in the 500 mg kg -1 Pb treatment; however, this removal rate was generally lower than that of Cd. In addition, the reduction state had the highest change rate, followed by the residual, acid soluble and oxidation states. For Pb, the residual state has the highest change rate, followed by the acid soluble state, reduction state and oxidation state. In addition, a significant correlation was observed between the soil Pb and Cd concentrations and the concentrations of Pb and Cd that accumulated in the belowground biomass of the barnyard grass, but no significant correlation was observed between the soil Pb and Cd concentrations and the amounts of Pb and Cd that accumulated in the aboveground biomass of the barnyard grass. The highest transfer factor of Cd was 0.49, which occurred in the 5 mg kg -1 Cd treatment. The higher transfer factor of Pb was 0.48 in the 100 mg kg -1 Pb treatment. All of these factors indicate that the belowground biomass of barnyard grass plays a more important role in the remediation of Cd- and Pb-contaminated soils than the aboveground

  7. Tunable band offset and recombination in ZnO nanowire-CdTe quantum dot heterostructures

    Science.gov (United States)

    He, Haiping; Gan, Lu; Sun, Luwei; Ye, Zhizhen

    2017-10-01

    ZnO nanowire (NW)-CdTe quantum dot (QD) type-II heterostructures were constructed using hydrothermally grown ZnO and colloidal CdTe QDs. Photoluminescence (PL) spectroscopy was used to investigate the charge transfer and band offset between CdTe QDs and ZnO NWs. The results demonstrated that the PL shows obvious redshift and prolonged lifetime in the heterostructure, indicating that it originates from recombination between electrons localized in ZnO and holes localized in CdTe. The results reveal that the band offset and charge recombination can be tuned by the growth time or size of CdTe QDs. Our results demonstrate that PL can be a useful tool to evaluate the band alignment and charge recombination in type-II semiconductor heterostructures.

  8. Thermodynamics of Pb(ii) and Zn(ii) binding to MT-3, a neurologically important metallothionein.

    Science.gov (United States)

    Carpenter, M C; Shami Shah, A; DeSilva, S; Gleaton, A; Su, A; Goundie, B; Croteau, M L; Stevenson, M J; Wilcox, D E; Austin, R N

    2016-06-01

    Isothermal titration calorimetry (ITC) was used to quantify the thermodynamics of Pb(2+) and Zn(2+) binding to metallothionein-3 (MT-3). Pb(2+) binds to zinc-replete Zn7MT-3 displacing each zinc ion with a similar change in free energy (ΔG) and enthalpy (ΔH). EDTA chelation measurements of Zn7MT-3 and Pb7MT-3 reveal that both metal ions are extracted in a tri-phasic process, indicating that they bind to the protein in three populations with different binding thermodynamics. Metal binding is entropically favoured, with an enthalpic penalty that reflects the enthalpic cost of cysteine deprotonation accompanying thiolate ligation of the metal ions. These data indicate that Pb(2+) binding to both apo MT-3 and Zn7MT-3 is thermodynamically favourable, and implicate MT-3 in neuronal lead biochemistry.

  9. X-ray and magnetic studies of Zn 2 substituted Ni–Pb ferrites

    Indian Academy of Sciences (India)

    Seven samples of the polycrystalline, Ni1.25–ZnPb0.25Fe1.5O4 ( = 0.0, 0.1, 0.2, 0.3, 0.4, 0.5 and 0.6) ferrites, were prepared by usual double sintering ceramic method. X-ray diffraction patterns of the samples revealed single-phase cubic spinel structure. The magnetic properties were investigated by means of ...

  10. 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.

  11. FITODEGRADASI DENGAN TANAMAN PACING (Speciosus Cheilocostus UNTUK MENURUNKAN KANDUNGAN Pb, Cd Dan Hg LIMBAH CAIR LABORATORIUM

    Directory of Open Access Journals (Sweden)

    Ni Nyoman Trisnawati

    2016-06-01

    Full Text Available ABSTRAK: UPT. Laboratorium Analitik Universitas Udayana menghasilkan limbah yang mengandung bahan-bahan kimia berbahaya. Sistem pengolahan air limbah yaitu fitodegradasi, menggunakan tanaman Pacing (Cheilocostus speciosus telah dicoba untuk mengolah limbah cair laboratorium. Konstruksi unit pengolahan terdiri dari sebuah bak terbuat dari beton dengan media  tanah berukuran 7 m x 1,2 m x 0,34 m yang ditumbuhi Pacing. Penelitian dilakukan selama dua minggu meliputi penelitian eksperimental, observasi pre dan post perlakuan. Efektivitas sistem  fitoremediasi dalam menurunkan kandungan Hg adalah 100% pada hari ketiga, Cd sebesar 77,17 % dan Pb sebesar 9,50 % pada hari keempat. Kandungan Pb, Cd dan Hg berkurang secara signifikan setelah fitoremediasi.   ABSTRACT: UPT Analytical Laboratory of Udayana University produced liquid waste which contained dangerous chemicals such as : lead (Pb, Cadmium (Cd, and Mercury (Hg. Processing system of liquid waste using phytodegradation of pacing plant (Cheilocostus speciosus has been studied to reduce the concentrations of heavy metals of laboratory liquid waste. The construction of the processing unit consisted of conerete tank filled with soil media grown over with pacing plant. The size of the tank was; 7 meters in length, 1.2 meters in width and 0.35 meters in depth. The duration  of the experiment was 2 weeks, by observation of pre and post treatment to record the effectivenesss of the pacing plants in reducing the concentrations of Pb, Cd and Hg in liquid waste. The results showed the effectiveness of the system in reducing the concentration of Pb, Cd and Hg were 9,50 %; 77,17 % and 100 % respectively.  The concentration of  Pb, Cd and Hg decreased significantly after treatment.

  12. Comparative adsorption of Pb2+ and Cd2+ by cow manure and its vermicompost.

    Science.gov (United States)

    Zhu, Weiqin; Du, Wenhui; Shen, Xuyang; Zhang, Hangjun; Ding, Ying

    2017-08-01

    Organic waste has great potential for use as an amendment to immobilize heavy metals in the environment. Therefore, this study investigates various properties of cow manure (CM) and its derived vermicompost (CV), including the pH, cationic exchangeable capacity (CEC), elemental composition and surface structure, to determine the potential of these waste products to remove Pb 2+ and Cd 2+ from solution. The results demonstrate that CV has a much higher pH, CEC and more irregular pores than CM and is enriched with minerals and ash content but has a lower C, H, O and N content. Adsorption isotherms studies shows that the adsorption of Pb 2+ and Cd 2+ onto either CM or CV follows a Langmuir model and presents maximum Pb 2+ and Cd 2+ adsorption capacities of 102.77 mg g -1 and 38.11 mg g -1 onto CM and 170.65 and 43.01 mg g -1 onto CV, respectively. Kinetic studies show that the adsorption of Pb 2+ onto CM and CV fits an Elovich model, whereas the adsorption of Cd 2+ onto CM and CV fits a pseudo-second-order model. Desorption studies indicate that CV is more effective than CM in removing Pb 2+ and Cd 2+ . FTIR analysis demonstrates that the adsorption of Pb 2+ and Cd 2+ onto CM mainly depends on existed aliphatic alcohol, aromatic acid as well as new produced carbonates, whereas that onto CV may be contributed by the existed aliphatic alcohol, aromatic acids as well as some carbonates and phosphates. Thus, vermicomposting disposal of cow manure with destination mineral addition may broaden the way of its recycle and environmental usage. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Modelling the leaching of Pb, Cd, As, and Cr from cementitious waste using PHREEQC

    International Nuclear Information System (INIS)

    Halim, Cheryl E.; Short, Stephen A.; Scott, Jason A.; Amal, Rose; Low, Gary

    2005-01-01

    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 CrO 4 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 Ca 3 (AsO 4 ) 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

  14. Geology, mineralization, mineral chemistry, and ore-fluid conditions of Irankuh Pb-Zn mining district, south of Isfahan

    Directory of Open Access Journals (Sweden)

    Mohammad Hassan Karimpour

    2017-11-01

    within carbonate host rocks, whereas Fe-rich sphalerite, galena, pyrite, minor chalcopyrite, low Fe-dolomite, quartz, bituminous, ± barite ± calcite are important primary minerals at clastic host rocks. There is positive correlation between Ag and Sb values within galena mineral. Sb/Bi ratio in galena is up to 20, which is an indicator of low temperature deposits (Malakhov, 1968. The Irankuh homogenization temperature (170 to 260 ºC is higher than that of US Mississippi-type deposits (80 to 120 ºC. Based on comparison of Th and Fe and Cd contents in sphalerite from Irankuh and US deposits (Viets et al., 1992, homogenization temperature of deposit has a positive relation with Fe values and a negative relation with Cd contents in sphalerite. Fe content in Irankuh sphalerite has reached up to 5% and Cd value is lower than 2000 ppm. In addition, carbonate hosted rock hydrothermal dolomites that are Fe-rich and ankrite have formed at some places. The evidence shows that Irankuh ore-fluid is Fe-rich. However, clastic hosted rock hydrothermal dolomites are low-Fe due to reaction of Fe and S resulting in pyrite formation. Based on O isotope (16–19 ‰ value from hydrothermal dolomites (Ghazban et al., 1994, ore-fluid has been derived from continental crust. Results Fe-rich sphalerite and dolomite and ankrite are the most important characteristics of Irankuh mining district. Temperature and Fe-rich nature of ore-fluid and mineralogy signatures of Irankuh area can be used for exploration of this type of mineralization in Iran and the world. The Irankuh mining district is MVT type mineralization. Acknowledgements The Research Division of the Ferdowsi University of Mashhad, Iran, supported this study (Project No. 40221.3. Thanks to Bama Co. (especially Mr. Eslami for the collaborations. References Ayati, F., Dehghani, H., Mokhtari, A.R. and Mojtahedzadeh, H., 2013. Geochemistry and mineralogy studies of Gushfil Pb-Zn deposit, Irankuh, Isfahan. Analytical and Numerical Methods

  15. Pre-concentration of Pb, Cd, and Ni in river water using back extraction method

    Science.gov (United States)

    Koesmawati, T. A.; Moelyo, M.; Rizqiani, A.; Tanuwidjaja, S.

    2017-03-01

    Dissolved heavy metals such as Pb, Cd and Ni in natural water can be the source of harmful contaminant for human health and aquatic life in aquatic systems. Particular treatment is needed for low concentration of metals in water samples using Flame Atomic Absorption Spectrophotometer (FAAS) measurement. The sample was collected from Cikapundung River in Siliwangi and Dayeuhkolot, Bandung. Back-extraction procedure was used as an alternative method for pre-concentration in trace metal analysis. Ammonium Pyrrolidine Dithiocarbamate (APDC) and Diethylammonium Diethyldithiocarbamate (DDDC) in Methyl Isobuthyl Ketone (MIBK) were used as chelating agent. In this study, the application of back-extraction procedure using APDC/DDDC chelating agent in MIBK resulted the detection limit of 2.2 μg/L for Pb; 1.6 μg/L for Cd; and 1.0 μg/L for Ni. The result showed that sensitivity was increased 4 times for Pb, 6 times for Ni, and none for Cd. The highest concentration of Pb in Cikapundung River was found 8.0 μg/L. All Ni concentration in water samples were under limit of detection. Method validation was conducted in this study and found that the value of correlation coefficient (r) for Pb, Cd and Ni was 0.9995, 0.9960 and 0.9994, respectively. The recovery value for Pb, Cd and Ni were 112.0, 81.5 and 85.9%, respectively in Cikapundung River, and 119.0, 83.5 and 85.9 %, respectively, in groundwater samples. The value of Relative Standard Deviation (RSD) for Pb, Cd and Ni in Cikapundung River were 2.01, 2.15 and 6.40%, respectively. On the other hand, the value of RSD of Pb, Cd and Ni in groundwater were 2.70, 3.30 and 7.69%, respectively. In conclusion, back-extraction method can be applied as pre-concentration for low concentration of Pb and Ni in river water samples.

  16. XPS-and-DFT analyses of the Pb 4f — Zn 3s and Pb 5d — O 2s overlapped ambiguity contributions to the final electronic structure of bulk and thin-film Pb-modulated zincite

    Energy Technology Data Exchange (ETDEWEB)

    Zatsepin, D.A. [M.N. Miheev Institute of Metal Physics of Ural Branch of Russian Academy of Sciences, 620990 Yekaterinburg (Russian Federation); Institute of Physics and Technology, Ural Federal University, 620002 Yekaterinburg (Russian Federation); Boukhvalov, D.W., E-mail: danil@hanyang.ac.kr [Department of Chemistry, Hanyang University, 17 Haengdang-dong, Seongdong-gu, Seoul 133-791 (Korea, Republic of); Theoretical Physics and Applied Mathematics Department, Ural Federal University,Mira Street 19, 620002 Yekaterinburg (Russian Federation); Gavrilov, N.V. [Institute of Electrophysics, Russian Academy of Sciences, Ural Branch, 620990 Yekaterinburg (Russian Federation); Kurmaev, E.Z. [M.N. Miheev Institute of Metal Physics of Ural Branch of Russian Academy of Sciences, 620990 Yekaterinburg (Russian Federation); Institute of Physics and Technology, Ural Federal University, 620002 Yekaterinburg (Russian Federation); Zatsepin, A.F. [Institute of Physics and Technology, Ural Federal University, 620002 Yekaterinburg (Russian Federation); Cui, L. [Shenzhen Graduate School, Harbin Institute of Technology, Shenzhen 518055 (China); Shur, V. Ya.; Esin, A.A. [Institute of Natural Sciences, Ural Federal University, 51 Lenin Ave, 620000 Yekaterinburg (Russian Federation)

    2017-05-31

    Highlights: • Two modes of ZnO:Pb in the bulk and surface morphologies were established: the high- and low-interaction. • It was shown the ambiguity contribution of Pb 4f − Zn 3s and Pb 5d − O 2s states into final electronic structure. • The main type of defects is PbO-like with some PbO{sub 2}-like contributions. • An applied wurzite-like structural model well agrees with experimental data obtained for zincite. - Abstract: The electronic structures of zincite Pb-modulated bulk and thin-films were studied via X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) techniques. Both XPS data and DFT-calculations allowed the derivation of two different Pb-embedding scenarios into the ZnO-hosts. These included the high-interaction mode of Pb-impurity with initial zinc-oxygen host-lattice for the bulk morphology, accompanied with low Pb-metal losses; and the low-interaction mode for thin-films, where there was intake of Pb-impurities into the hollows of the surface. Despite dissimilar mechanisms of Pb-impurity accumulation and distribution in the bulk and thin-films zincite host-matrices, the strong Pb 4f — Zn 3s and Pb 5d — O 2s overlapped ambiguity contribution to the appropriate core-level structure and valence bands was established by XPS analysis and reproduced with the help of DFT-calculations. It was shown that the microscopic structure of the embedded lead-impurity played a crucial role in the Pb ion-beam stimulated synthesis of secondary lead-oxygen phases via large-area defect fabrication, and the difference among zincite and wurzite polymorphs played almost no role in this case.

  17. Bioremediation of Zn, Cu, Mg and Pb in Fresh Domestic Sewage by Brevibacterium sp

    International Nuclear Information System (INIS)

    Ojoawo, S. O.; Rao, C. V.; Goveas, L. C.

    2016-01-01

    The study applied an isolated Brevibacterium sp. (MTCC 10313) for bioremediation of Zn, Cu, Mg and Pb in domestic sewage. Batch culture experiments were performed on both the fresh and stale sewage samples with glucose supplementation of 1-8g/l. Nutrient broth medium was prepared, sterilized and p H adjusted to 6.5-6.8. 1% of the Brevibacteria sp. stock was inoculated into the broth and maintained at 370C for 24 hours in shaker incubator at 120 rpm. Another 1% of fresh grown sub-culture of broth was inoculated into supplemented and sterilized samples. Optical Density was taken at 600nm, growth monitored over 12 days, cultured samples denatured with TCA and centrifuged, supernatants filtered and analyzed with AAS, Settled pellets oven dried, subjected to SEM analysis for morphology and constituents determination. Fresh sewage samples permitted bacterial growth and facilitated bioremediation of Zn, Cu and Mg through metal uptake and bioabsoption by Brevibacteria sp. This effectively reduced concentration of heavy metals, with treatment efficiency order Cu>Zn>Mg, and respective removal percentages of 77, 63 and 55. The optimum glucose concentration for effective bioremediation found as 2g/l for Zn and Cu, and 8g/l for Mg. Pb was resistant to bioremediation with Brevibacteria sp. Stale sewage produced inhibitory substances preventing adequate growth of bacterium with no bioremediation. Bioremediation with Brevibacteria sp. is found effective in removal of micro-units of Zn, Cu and Mg from domestic sewage. As a readily available low-cost agent, it is recommended for large- scale application on those metals while Pb should be further subjected to advanced treatments.

  18. Reactive flow models of the Anarraaq Zn-Pb-Ag deposit, Red Dog district, Alaska

    Science.gov (United States)

    Schardt, Christian; Garven, Grant; Kelley, Karen D.; Leach, David L.

    2008-09-01

    The Red Dog ore deposit district in the Brooks Range of northern Alaska is host to several high-grade, shale-hosted Zn + Pb deposits. Due to the complex history and deformation of these ore deposits, the geological and hydrological conditions at the time of formation are poorly understood. Using geological observations and fluid inclusion data as constraints, numerical heat and fluid flow simulations of the Anarraaq ore deposit environment and coupled reactive flow simulations of a section of the ore body were conducted to gain more insight into the conditions of ore body formation. Results suggest that the ore body and associated base metal zonation may have formed by the mixing of oxidized, saline, metal-bearing hydrothermal fluids (<200°C) with reducing, HS-rich pore fluids within radiolarite-rich host rocks. Sphalerite and galena concentrations and base metal sulfide distribution are primarily controlled by the nature of the pore fluids, i.e., the extent and duration of the HS- source. Forward modeling results also predict the distribution of pyrite and quartz in agreement with field observations and indicate a reaction front moving from the initial mixing interface into the radiolarite rocks. Heuristic mass calculations suggest that ore grades and base metal accumulation comparable to those found in the field (18% Zn, 5% Pb) are predicted to be reached after about 0.3 My for initial conditions (30 ppm Zn, 3 ppm Pb; 20% deposition efficiency).

  19. Study of Zn-Pb ore tailings and their potential in cement technology

    Science.gov (United States)

    Nouairi, J.; Hajjaji, W.; Costa, C. S.; Senff, L.; Patinha, C.; Ferreira da Silva, E.; Labrincha, J. A.; Rocha, F.; Medhioub, M.

    2018-03-01

    This paper describes the synthesis of sulfobelite clinkers incorporating mining rejects. The targeted Zn-Pb tailing wastes generated in the diapiric zone (NW Tunisia) were tested in clinker/cement compositions to ensure the inertization of existing hazardous heavy metals. Mineralogical composition of the two selected samples revealed calcite, dolomite, quartz, kaolinite, galena, pyrite and gypsum as crystalline phases. Vertical distributions of dominant heavy metals (Pb, Zn and Cu) in soil profiles show enrichment in the surface layers and decrease towards the depth. In sintered clinkers powders, the presence of the targeted crystalline phases (trialuminate sulphate (C4A3Š), belite (C2S), and ferrite (C4AF)) are in the predicted desirable amounts. Heat flow generated during the hydration of different cement pastes showed a slower reaction for clinkers with higher amounts of C4A3Š or constituted by coarser particles. After 28 days curing, the best mechanical resistance (24.34 MPa under compression) was obtained for the clinker calcined at 1350 °C and showing a suitable particle size distribution. Concerning heavy metals, immobilisation of 75-85% of Pb, Zn and Cu was assessed in the mortars formulated with the produced clinker/cement, posing no hazardous risks to the environment.

  20. Evaluation of potential of adsorption of U, Th, Pb, Zn and Ni by coconut fibers

    International Nuclear Information System (INIS)

    Monteiro, Raquel Almeida

    2009-01-01

    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 Pb 2+ and Zn 2+ ions and the Freundlich equation for UO 2 2 + , Th 4+ and Ni 2+ 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)

  1. Formation of self assembled PbTe quantum dots in CdTe on Si(111)

    Science.gov (United States)

    Felder, F.; Fognini, A.; Rahim, M.; Fill, M.; Müller, E.; Zogg, H.

    2010-01-01

    We describe the growth and formation of self assembled PbTe quantum dots in a CdTe host on a silicon (111) substrate. Annealing yields different photoluminescence spectra depending on initial PbTe layer thickness, thickness of the CdTe cap layer and annealing temperature. Generally two distinct emission peaks at ˜0.3 eV and ˜0.45 eV are visible. Model calculations explaining their temperature dependence are performed. The dot size corresponds well with the estimated sizes from electron microscopy images. The quantum dots may be used as absorber within a mid-infrared detector.

  2. BIOSORPTION OF Zn2+ AND Cd2+ IN A TWO-METAL SYSTEM BY NANNOCHLOROPSIS SALINA

    OpenAIRE

    Hala, Yusafir

    2013-01-01

    Although Zn2+ and Cd2+ ions in waters are pollutant with a large amount due to mining and industrial activities, information relating to the use of marine microalgae Nannochloropsis salina to absorb both types of metals is still very little. A marine microalga, N. salina, was used as biosorbent for the metal ions in water. Concentration of each ion (Zn2+ and Cd2+ ) was 10 mg L???1 and the concentration ratio of Zn2+ to Cd2+ in the two-metal system (a combi...

  3. HYDROTALSIT Zn-Al-EDTA SEBAGAI ADSORBEN UNTUK POLUTAN ION Pb(II DI LINGKUNGAN Zn-Al-EDTA Hydrotalcite as Adsorbent for Pb(II Ion Pollutant in The Environment

    Directory of Open Access Journals (Sweden)

    Roto Roto

    2015-07-01

    Full Text Available ABSTRAK Polusi ion Pb(II di dalam lingkungan perairan cenderung naik seiring peningkatan jumlah industri smelter dan daur ulang aki bekas. Penelitian ini bertujuan untuk menguji kemampuan hidrotalsit Zn-Al-EDTA sebagai adsorben ion Pb(II dalam air secara mendalam. Hidrotalsit Zn-Al-NO3 disintesis dengan metode kopresipitasi dan hidrotermal pada temperatur 100 °C selama 15 jam. Hidrotalsit Zn-Al-EDTA diperoleh dengan penukaran ion. Keasaman larutan, kinetika dan kapasitas adsorpsi diteliti. Hidrotalsit Zn-Al-EDTA memiliki d003 sebesar 14,52 Å sementara Zn-Al-NO3 sebesar 8,90 Å. Spektra FTIR menunjukkan keberadaan serapan gugus C=O pada bilangan gelombang 1684,77 cm-1. Kondisi optimum adsorpsi ion Pb(II terjadi pada pH 4, waktu kontak 60 menit dan kapasitas adsorpsi diperoleh 2,07 mg/g pada konsentrasi awal 10 mg/L dengan berat adsorben 0,100 g. Adsorpsi ion Pb(II oleh hidrotalsit Zn-Al-EDTA mengikuti reaksi pseudo orde dua dengan tetapan laju adsorpsi sebesar 8,90 g mmol-1min-1. Adsorpsi ion Pb(II oleh Zn-Al-EDTA terjadi karena  pembentukan khelat Pb-EDTA di dalam struktur hidrotalsit. Hasil ini diharapkan mampu memberikan kontribusi yang lebih luas di dalam pengendalian konsentrasi Pb(II di lingkungan. ABSTRACT Polution by Pb(II ion in the water environment tends to increase due the increase in the number of lead smelter and lead acid battery recycling industries. This work aims at studying in details the ability of Zn-Al-EDTA hydrotalcite as adsorbent for Pb(II ion in the environment. The Zn-Al-NO3 hydrotalcite was synthesized first by coprecipitation method followed by hydrothermal treatment at 100 °C for 15 h. The Zn-Al-EDTA hydrotalcite was later obtained by ion exchange process. The solution pH, kinetics and adsorption capacity were studied. The XRD data showed that Zn-Al-EDTA and Zn-Al-NO3 hydrotalcites have d003 of 14.52 and 8.90 Å, respectively. The FTIR spectra suggested that C=O group was observed with absorption band at 1684

  4. CdS/ZnS nanocomposites: from mechanochemical synthesis to cytotoxicity issues.

    Science.gov (United States)

    Baláž, Peter; Baláž, Matej; Dutková, Erika; Zorkovská, Anna; Kováč, Jaroslav; Hronec, Pavol; Kováč, Jaroslav; Čaplovičová, Mária; Mojžiš, Ján; Mojžišová, Gabriela; Eliyas, Alexander; Kostova, Nina G

    2016-01-01

    CdS/ZnS nanocomposites have been prepared by a two-step solid-state mechanochemical synthesis. CdS has been prepared from cadmium acetate and sodium sulfide precursors in the first step. The obtained cubic CdS (hawleyite, JCPDS 00-010-0454) was then mixed in the second step with the cubic ZnS (sphalerite, JCPDS 00-005-0566) synthesized mechanochemically from the analogous precursors. The crystallite sizes of the new type CdS/ZnS nanocomposite, calculated based on the XRD data, were 3-4 nm for both phases. The synthesized nanoparticles have been further characterized by high-resolution transmission electron microscopy (HRTEM) and micro-photoluminescence (μPL) spectroscopy. The PL emission peaks in the PL spectra are attributed to the recombination of holes/electrons in the nanocomposites occurring in depth associated with Cd, Zn vacancies and S interstitials. Their photocatalytic activity was also measured. In the photocatalytic activity tests to decolorize Methyl Orange dye aqueous solution, the process is faster and its effectivity is higher when using CdS/ZnS nanocomposite, compared to single phase CdS. Very low cytotoxic activity (high viability) of the cancer cell lines (selected as models of living cells) has been evidenced for CdS/ZnS in comparison with CdS alone. This fact is in a close relationship with Cd(II) ions dissolution tested in a physiological solution. The concentration of cadmium dissolved from CdS/ZnS nanocomposites with variable Cd:Zn ratio was 2.5-5.0 μg.mL(-1), whereas the concentration for pure CdS was much higher - 53 μg.ml(-1). The presence of ZnS in the nanocrystalline composite strongly reduced the release of cadmium into the physiological solution, which simulated the environment in the human body. The obtained CdS/ZnS quantum dots can serve as labeling media and co-agents in future anti-cancer drugs, because of their potential in theranostic applications. Copyright © 2015 Elsevier B.V. All rights reserved.

  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

    2013-10-07

    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. 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

    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....... Values for concentration factors greater than unity were found for Cd in kidney (5.8) and for Hg in kidney, liver and muscle (3.6, 3.3 and 2.2, respectively) of whitefish....

  7. The first report of Pb and Zn accumulation in some native plants from the Peruvian Andes

    Science.gov (United States)

    Bech, Jaume; Duran, Paola; Poma, Wilfredo; Sánchez, Isidoro; Barceló, Juan; Roca, Núria; Boluda, Rafael; Roca-Pérez, Luís.; Poschenrieder, Charlotte

    2010-05-01

    Until recent decades little has been known about the remediation of mining sites using metalophytes in Latin America. Metal mining has helped to create severe and diverse environmental problems. The present study proposed to identify and characterize spontaneously growing heavy metal tolerant plant species in the area around the polimetalic mine in Hualgayoc (Cajamarca, Peru). These species are potentially useful for phytorremediation. Plant and soils from their rhizosphere were sampled and analized for concentration of As, Fe, Mn, Pb and Zn. Translocation Factor (TF) defined the metals concentrations ratio between shoots and root biomass and Shoot Accumulation Factor (SAF) the metal concentration ratio between shoot and soil concentration were determined and used to measure the effectiveness of a plant in concentrating metals into its biomass. The soils were neutral pH (7,4±0,5) with variable content of organic carbon (2,4±1,1) and loam texture: sand (42,9±10,8) and clay (16,7±4,6). According to the total metals, all samples exceeded toxicity thresholds, high Pb (20016 ± 32559 mg•kg-1) and Zn (22512 ± 13056 mg•kg-1) concentrations were detected. High shoot Pb and Zn concentrations were found in Plantaginaceae Plantago orbignyana (6998 and 9617 μg/g); Brassicaceae Lepidium bipinnatifidum (6886 and 5034 mg•kg-1) and Asteraceae Senecio sp (4253 and 3870 mg•kg-1) and Baccharis latifolia (2554 and 1284 mg•kg-1 respectively). The high values of TFs indicates that the plants effectively traslocated metales. Lepidium bipinnatifidum shows the highest TFs values (143 in Pb and 21,5 in Zn). The SAF values were much lower than those reported for other species such as Paspalum sp in the Peruvian copper mine, which may be due to a high top soil Pb and Zn concentrations. These species can surely be considered as interesting for phytoextraction, due not only to its accumulative capacity but also since they showed an elevated transfer factor and grew in the

  8. Raman and photoluminescence spectra of ZnTe/CdSe and ZnTe/CdTe tetrapod shaped nano-hetero structures

    Science.gov (United States)

    Fiore, Angela; Morello, Giovanni; Scremin, Barbara Federica

    2018-01-01

    In the present paper we report the Raman and photoluminescence characterization of two nano-hetero-structures of II-VI semiconductors, tetrapod shaped. The examined samples were constituted of a ZnTe core and either CdSe or CdTe arms. The main contributions to the Raman spectra were assigned to phonons from the arms of the structures, but the weak contribution from the ZnTe core was identified from the separate measurement of spectra of the seeds used for growing the arms. The simultaneously acquired photoluminescence spectra allowed identifying an intense band characteristic of a Type II band alignment at 920 nm for the ZnTe/CdSe nanostructures.

  9. Field evaluation of Cd and Zn phytoextraction potential by the hyperaccumulators Thlaspi caerulescens and Arabidopsis halleri

    International Nuclear Information System (INIS)

    McGrath, S.P.; Lombi, E.; Gray, C.W.; Caille, N.; Dunham, S.J.; Zhao, F.J.

    2006-01-01

    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

  10. 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...

  11. The influence of CdSe and ZnSe nanoparticles on the optical properties of Sm3+ ions in lead borate glasses

    Science.gov (United States)

    Mallur, Saisudha B.; Heidorn, William D.; Fatokun, Stephen O.; Joshi, Krishna D.; Bista, Sandip S.; Babu, Panakkattu K.

    2017-03-01

    The effect of glass composition and the presence of CdSe/ZnSe nanoparticles (NPs) on the optical absorption and fluorescence of Sm-doped lead borate glasses are studied. Three sets of glass samples xPbO:(99.5-x) B2O3:0.5Sm2O3, x = 29.5-69.5 mol%, xPbO:(96.5-x) B2O3:0.5Sm2O3: 3CdSe/ZnSe, x = 36.5, and 56.5 mol% are prepared. NPs are grown by annealing these glasses just below the glass transition temperature. Average size of both types of NPs increases with annealing time; however, CdSe NPs grew to a larger size range (2 to 20 nm) compared to ZnSe NPs (1 to 16 nm). We analyzed the hypersensitive transition, intensity parameters, radiative transition probability, stimulated emission cross section (σp), and the area ratio of the electric dipole/magnetic dipole transitions of Sm3+. The intensity parameters show a minimum at 11 h annealing for 36.5 mol% and a maximum for the same annealing duration in 56.5 mol% PbO containing CdSe NPs. The σp for 56.5 mol% of PbO with CdSe NPs is found to be a maximum when the average NP size is around 14 nm. ZnSe NPs containing glasses also show significant changes in σp when the average particle size is 16 nm, for 36.5 mol% PbO. Our results suggest that the optical properties of Sm3+ in lead borate glasses are sensitive to its electronic environment which can be modified by varying the base glass composition and/or incorporating large NPs of CdSe/ZnSe. The large σp values that we observe for some of the glass compositions make them attractive materials for photonic devices and photovoltaic applications.

  12. The influence of CdSe and ZnSe nanoparticles on the optical properties of Sm{sup 3+} ions in lead borate glasses

    Energy Technology Data Exchange (ETDEWEB)

    Mallur, Saisudha B.; Heidorn, William D.; Fatokun, Stephen O.; Joshi, Krishna D.; Bista, Sandip S.; Babu, Panakkattu K., E-mail: PK-Babu@wiu.edu [Western Illinois University, Department of Physics (United States)

    2017-03-15

    The effect of glass composition and the presence of CdSe/ZnSe nanoparticles (NPs) on the optical absorption and fluorescence of Sm-doped lead borate glasses are studied. Three sets of glass samples xPbO:(99.5-x) B{sub 2}O{sub 3}:0.5Sm{sub 2}O{sub 3}, x = 29.5–69.5 mol%, xPbO:(96.5-x) B{sub 2}O{sub 3}:0.5Sm{sub 2}O{sub 3}: 3CdSe/ZnSe, x = 36.5, and 56.5 mol% are prepared. NPs are grown by annealing these glasses just below the glass transition temperature. Average size of both types of NPs increases with annealing time; however, CdSe NPs grew to a larger size range (2 to 20 nm) compared to ZnSe NPs (1 to 16 nm). We analyzed the hypersensitive transition, intensity parameters, radiative transition probability, stimulated emission cross section (σ{sub p}), and the area ratio of the electric dipole/magnetic dipole transitions of Sm{sup 3+}. The intensity parameters show a minimum at 11 h annealing for 36.5 mol% and a maximum for the same annealing duration in 56.5 mol% PbO containing CdSe NPs. The σ{sub p} for 56.5 mol% of PbO with CdSe NPs is found to be a maximum when the average NP size is around 14 nm. ZnSe NPs containing glasses also show significant changes in σ{sub p} when the average particle size is ~16 nm, for 36.5 mol% PbO. Our results suggest that the optical properties of Sm{sup 3+} in lead borate glasses are sensitive to its electronic environment which can be modified by varying the base glass composition and/or incorporating large NPs of CdSe/ZnSe. The large σ{sub p} values that we observe for some of the glass compositions make them attractive materials for photonic devices and photovoltaic applications.

  13. CdO necklace like nanobeads decorated with PbS nanoparticles: Room temperature LPG sensor

    Energy Technology Data Exchange (ETDEWEB)

    Sonawane, N.B. [Department of Physics, School of Physical Sciences, North Maharashtra University, Jalgaon, 425001 M.S. (India); K.A.M.P. & N.K.P. Science College, Pimpalner, Sakri, Dhule, M.S. (India); Baviskar, P.K. [Department of Physics, School of Physical Sciences, North Maharashtra University, Jalgaon, 425001 M.S. (India); Ahire, R.R. [S.G. Patil Science, Sakri, Dhule, M.S. (India); Sankapal, B.R., E-mail: brsankapal@gmail.com [Nano Materials and Device Laboratory, Department of Applied Physics, Visvesvaraya National Institute of Technology, South Ambazari Road, Nagpur, 440010 M.S. (India)

    2017-04-15

    Simple chemical route has been employed to grow interconnected nanobeads of CdO having necklace like structure through air annealing of cadmium hydroxide nanowires. This nanobeads of n-CdO with high surface area has been decorated with p-PbS nanoparticles resulting in the formation of nano-heterojunction which has been utilized effectively as room temperature liquefied petroleum gas (LPG) sensor. The room temperature gas response towards C{sub 2}H{sub 5}OH, Cl{sub 2}, NH{sub 3}, CO{sub 2} and LPG was investigated, among which LPG exhibits significant response. The maximum gas response of 51.10% is achieved with 94.54% stability upon exposure of 1176 ppm concentration of LPG at room temperature (27 °C). The resulting parameters like gas response, response and recovery time along with stability studies has been studied and results are discussed herein. - Highlights: • Conversion of Cd(OH){sub 2} nanowires to CdO nanonecklace by air annealing at 290 °C. • Decoration of PbS nanoparticles over CdO nanobeads by SILAR method. • Formation of n-CdO/p-PbS nano-heterojunction as room temperature LPG sensor. • Maximum gas response of 51.10% with 94.54% stability.

  14. Increasing photon absorption and stability of PbS quantum dot solar cells using a ZnO interlayer

    NARCIS (Netherlands)

    Lai, Lai-Hung; Speirs, Mark J.; Chang, Feng-Kuei; Piveteau, Laura; Kovalenko, Maksym V.; Chen, Jen-Sue; Wu, Jih-Jen; Loi, Maria A.

    2015-01-01

    We compared PbS quantum dot (QD) solar cells with different cathode interlayer materials, namely, LiF and ZnO nanoparticles, using the same device structure. Solar cells fabricated with the ZnO interlayer gave a power conversion efficiency of 4.8%, which is higher (above the experimental variation)

  15. Quantum dot cosensitized solar cell based on PMOT@CdSe@ZnO core shell nanostructures with dual emission

    Energy Technology Data Exchange (ETDEWEB)

    Sehgal, Preeti; Narula, Anudeep Kumar, E-mail: researchchemlab58@gmail.com

    2016-01-15

    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 V{sub oc}=0.56 V and J{sub sc}=2.5 mA/cm{sup 2}. Upon annealing, the efficiency of the device was enhanced to 1.1609% with V{sub oc}=0.58, J{sub sc}=3.2 mA/cm{sup 2}. - Highlights: • Synthesized PMOT@CdSe@ZnO is biluminescent in nature. • A power conversion efficiency of 0.989% was achieved with PMOT@CdSe@ZnO device which is superior to CdSe@ZnO and PMOT@ZnO. • Upon annealing, an efficiency of 1.1609% was achieved for device PMOT@CdSe@ZnO.

  16. On the response of alloyed ZnCdSeS quantum dot films

    Directory of Open Access Journals (Sweden)

    I. Valais

    Full Text Available The aim of this work was to prepare composite ZnCdSeS quantum dot (QD flexible films and to examine their optical properties under ultraviolet excitation. PMMA/QD ZnCdSeS composite films, with emission covering the visual spectrum (480–630 nm were prepared with concentrations 10 mg/mL and 20 mg/mL by homogenously diluting dry powder QD samples in toluene and subsequently mixing with a PMMA/MMA polymer solution to the final ZnCdSeS/Toluene mixture. Scanning electron microscopy (SEM images of the produced films were obtained. The ZnCdSeS films were excited by ultraviolet light of varying intensities and the spectral matching with various optical detectors was estimated.

  17. Assessment of Pb, Zn, Cu, Ni and Cr in vegetables grown around Zanjan

    Directory of Open Access Journals (Sweden)

    A. Afshari

    2017-05-01

    Full Text Available This study was conducted aimed to assess the potential risk of heavy metals on human health resulting from consumption of vegetables. To this end, the vegetables grown around town and industrial center of Zanjan were sampled randomly. Plant samples were digested using hydrochloric acid (HCL 2 M and concentration of elements (Pb, Zn, Cu, Ni and Cr were recorded by atomic absorption. Obtained means of heavy metals in all vegetables (N= 32 for Zn, Pb, Cu, Ni and Cr is 98.8, 31.9, 19.3, 4.4 and 2.3 mg/kg, respectively. The highest amount of metal pollution index (MPI in the basil and the lowest was observed in the garden cress (respectively 16.46 and 4.88. Daily intake (EDI for zinc, copper and chromium in all age groups was lower than the provisional tolerable daily intake (PTDI. This amount for nickel was 2, 1.6 and 1.3 %, and for Pb 28.1, 22 and 19 % higher than PTDI in children, adults and seniors, respectively. The potential risk (THQ was calculated in all age groups as Pb>>Cu>Zn>Ni>Cr. The potential risks (THQ of chromium, nickel and zinc were calculated lower than 1, for copper a bit more of 1 and for lead much higher than 1. Health index (HI for children, adults and the elderly was estimated 31.331, 24.58 and 21.14, respectively, with the largest contribution of the lead (89.7%.

  18. A note on urinary Cd, Cr, Mn and Pb, in students of the University of ...

    African Journals Online (AJOL)

    A preliminary investigation of heavy metals exposure of students of the University of Agriculture, Makurdi in Central Nigeria involved AAS analysis of urine from ten (10) of the students (five each of female and male volunteers). Results indicate that the concentrations of Cd, Cr, Mn and Pb showed no discrimination between ...

  19. Levels of As, Pb, Cd and Fe in Suspended Particulate Matter (SPM ...

    African Journals Online (AJOL)

    Suspended Particulate Matter (SPM) collected from three different artisans' workshops was analyzed for As, Cd, Pb and Fe by Atomic Absorption Spectrophotometry (AAS). The range of SPM concentrations for the three workshops was 583-20,166Bg/m3. The highest concentrations of these elements were observed in Motor ...

  20. 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...

  1. Ecological effects of some heavy metals (Cd, Pb, Hg, Cr) pollution of ...

    African Journals Online (AJOL)

    STORAGESEVER

    2008-06-17

    Jun 17, 2008 ... reaching the lakes through their catchments area and the atmosphere. Typical results of human activities proved to be elevated levels of heavy metals present in fresh water, and among these microelements lead (Pb), cadmium. (Cd), mercury (Hg), chrome (Cr) are most specific. (Farkas et al., 2001).

  2. 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.

  3. Behaviours of MeCl2 (Me: Pb and Cd) during thermal treatment of ...

    African Journals Online (AJOL)

    hope&shola

    the emissions of both elements at low temperature (≤1000°C) and inhibited their emissions at high ... the mixtures. The heat-treated product containing anorthite as the major crystalline phase not only retain more amounts of Pb and Cd in its composition but also emit .... compounds due to reaction of lime with kaolinite at.

  4. Kinetic and equilibrium studies of Pb(II) and Cd(II) adsorption on ...

    African Journals Online (AJOL)

    The adsorption behavior of NaOH-activated African wild mango (Irvingia gabonensis) shell with respect to Pb2+ and Cd2+ has been studied in order to consider its application to purify metal finishing waste water. The optimum conditions of adsorption were determined by investigating the initial metal ions concentration, ...

  5. KINETIC AND EQUILIBRIUM STUDIES OF Pb(II) AND Cd(II ...

    African Journals Online (AJOL)

    Irvingia gabonensis) shell with respect to Pb2+ and Cd2+ has been studied in order to consider its application to purify metal finishing waste water. The optimum conditions of adsorption were determined by investigating the initial metal ions ...

  6. Chemical Bath Deposition and characterization of CdS – PbS thin ...

    African Journals Online (AJOL)

    ... exponentially between the second half of the visible and near infra-red regions. The films have peak reflectance within the visible region. The films showed good characteristics for deployment not only as UV filters but also in solar control coating applications. Keywords: Chemical bath, CdS, PbS, Thin Films, transmittance.

  7. Equilibrium and kinetic studies of Cu (II), Cd (II), Pb (II) and Fe (II ...

    African Journals Online (AJOL)

    Langmuir isotherm and pseudo-second order models were used to analyse the equilibrium and kinetic experimental data respectively. Equilibrium experimental data of Cu (II), Cd (II), Pb (II) and Fe (II) adsorption onto cocoa pod fitted well to Langmuir model and the kinetic data also fitted well to the pseudo-second order ...

  8. Adsorption equilibrium isotherms of Pb 2+ , Ni 2+ And Cd 2+ onto ...

    African Journals Online (AJOL)

    This study reports the adsorption equilibrium of lead (Pb2+), nickel (Ni2+) and cadmium (Cd2+) from aqueous solution by chicken's eggshells. The eggshells were collected from within Obafemi Awolowo University, Ile-Ife, Nigeria. They were washed with distilled water, air dried, pulverized, sieved into different particle sizes ...

  9. Seasonal Variation of Cd, Ni, Cu and Pb in Catfish, Sediment and ...

    African Journals Online (AJOL)

    The variation of some heavy metals Cd, Ni, Cu and Pb was conducted on sediment, cat fish and water samples from four stations in Ipo stream in dry and wet seasons. Atomic Absorption Spectrophotometry model 3700 was used to analyzed the samples The result revealed that the average metal concentrations in sediment ...

  10. Batch adsorption of heavy metals (Cu, Pb, Fe, Cr and Cd) from ...

    African Journals Online (AJOL)

    cinthia

    This study was carried out to evaluate the efficiency of metals (Cu, Fe, Pb, Cr and Cd) removal from mixed metal ions solution using coconut husk as adsorbent. The effects of varying contact time, initial metal ion concentration, adsorbent dose and pH on adsorption process of these metals were studied using synthetically ...

  11. Evaluation of toxic trace metals Cd and Pb in Arabian Sea waters

    Digital Repository Service at National Institute of Oceanography (India)

    Sanzgiri, S.; Mesquita, A.; Kureishy, T.W.; SenGupta, R.

    An attempt has been made to present a picture of the distribution of toxic trace elements Cd and Pb in the Northern Arabian Sea by applying an improved analytical technique for the detection of dissolved forms of the metals at nanogram levels...

  12. A Case Study of Landfill Leachate Using Coal Bottom Ash for the Removal of Cd2+, Zn2+ and Ni2+

    Directory of Open Access Journals (Sweden)

    Julia Ayala

    2016-11-01

    Full Text Available The removal of Cd2+, Zn2+ and Ni2+ by coal bottom ash has been investigated. In single metal system, metal uptake was studied in batch adsorption experiments as a function of pH (2–3, contact time (5–180 min, initial metal concentration (50–400 mg/L, adsorbent concentration (5–40 g/L, particle size, and ionic strength (0–1 M NaCl. Removal percentages of metals ions increased with increasing pH and dosage. Removal efficiency at lower concentrations was greater than at higher values. The maximum amount of metal ion adsorbed in milligrams per gram was 35.4, 35.1 and 34.6 mg/g for Zn2+, Cd2+ and Ni2+, respectively, starting out from an initial solution at pH 3. Simultaneous removal of Zn2+, Cd2+ and Ni2+ ions from ternary systems was also investigated and compared with that from single systems. Cd2+ uptake was significantly affected by the presence of competing ions at pH 2. The results obtained in the tests with landfill leachate showed that bottom ash is effective in simultaneously removing several heavy metals such as Ni, Zn, Cd, As, Mn, Cu, Co, Se, Hg, Ag, and Pb.

  13. Waste heaps left by historical Zn-Pb ore mining are hotspots of species diversity of beech forest understory vegetation.

    Science.gov (United States)

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

    2017-12-01

    Metalliferous mining and smelting industries are associated with very high levels of heavy metal(loid) contamination of the environment. Heavy metals have been proved to significantly influence the species diversity and composition of grassland communities, but little is known on their effects on forest understory vegetation. Therefore, the aim of this study was to investigate the effects of the presence of small heaps of waste rock left by historical Zn-Pb ore mining on understory vegetation. The heaps are scattered over vast areas of beech forests in southern Poland. Three types of study plots were established: (1) on waste heaps themselves, (2) in their vicinity (5-10m from the foot of the heaps, with no waste rock but potentially influenced by the heaps through drainage water), and (3) at least 100m from the foot of the heaps (pseudo-control). In all plots vegetation parameters, i.e., plant species number, cover and community composition, life forms and strategies, as well as basic soil properties were assessed. Although the heaps contained high concentrations of metals, namely Cd, Pb and Zn, they were characterised by higher cover and diversity of understory vegetation, including ancient forest and endangered species, in comparison to their surroundings. They were also characterised by the distinct species composition of their plant communities. This might have resulted from the beneficial influence of high pH and Ca content originating from waste rock composed of dolomite and calcite, as well as from increased habitat heterogeneity, e.g. soil skeleton and steeper slopes. Another important factor influencing the richness and composition of understory was tree cover, which relates to the light transmissibility of the canopy. Our study proved that the disturbance brought about by the former mining and processing of metal ores led to the formation of species-rich understory with high frequency and cover of naturally-valuable species. Copyright © 2017 Elsevier B

  14. Effect of Zn doping in Bi(Pb)-2212 superconducting ceramics

    International Nuclear Information System (INIS)

    Bouaicha, F.; Mosbah, M.F.; Boussouf, N.; Amira, A.; Ait-Kaki, A.

    2006-01-01

    The subject of substitution in the high-T c superconductors has received a great deal of interest. Substitution of bismuth by lead stabilizes and purifies the superconducting phase in Bi2223 and enhances T c in Bi2212. The substitution of Cu by magnetic or non magnetic element such as Fe, Ni, Co or Zn degrades significantly T c . The substitution by Zn is difficult because the amount that can be dissolved is limited. Samples of Bi 1.6 Pb 0.4 Sr 2 CaCu 2-y Zn y O 8+d (0≤y≤0.06) were prepared by a solid-state reaction method. The samples have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and AC susceptibility versus temperature measurements. Structural analysis shows that the obtained crystalline structure is mainly tetragonal with a c-axis lattice parameter decreasing with Zn content. AC susceptibility measurements show that the Zn doping decreases the superconducting volume fraction in the samples. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  15. X-ray fluorescence analysis of Pb, Fe and Zn in kohl

    Science.gov (United States)

    Daar, Eman; Alsubaie, Abdullah; Almugren, K. S.; Barnes, S.; Alanazi, A.; Alyahyawi, A.; Alomairy, S.; Al-Sulaiti, H.; Bradley, D. A.

    Kohl, a facial salve used in ancient times as a symbol of affluence, now enjoys more widespread traditional followings, for cosmetic, religious and supposed medicinal purposes. Popularly used by women and men of all ages, particularly those of North African, Middle Eastern, Southern Asia, Japanese and Chinese origins, it is also known to be used on neonates and children from such populations. With small-scale producers of kohl possessing a growing awareness of the adverse market impact of products that contain (lead) Pb and other toxicity related elements, some claim their products to be Pb-free, offering an apparent change from the more traditional galena-based (lead sulphide) media. Among the published physiological effects of exposure to Pb is that it replaces Ca in bones and teeth, making them weak and fragile, other impacts including nephrotoxicity, also linked with increased Pb blood levels in studies in Oman, Canada, Saudi Arabia, India and Pakistan. Current study involves XRF analysis of Pb, Fe and Zn concentrations in 135 samples of kohl from nine randomly selected suppliers (15 samples of each brand being represented). In pursuit of this, use was made of an in-house assembled facility comprising compact high-performance components, the arrangement offering sufficient sensitivity for the purposes of present study. In most of the samples investigated in the present study observation has been made of concentrations of Pb at elevated levels, quantification of those levels also demonstrating a need to address self-attenuation by the Pb itself. Significant concentration of Fe have also been found in several of the samples.

  16. Self-Powered Photoelectrochemical Biosensor Based on CdS/RGO/ZnO Nanowire Array Heterostructure.

    Science.gov (United States)

    Zhao, Kun; Yan, Xiaoqin; Gu, Yousong; Kang, Zhuo; Bai, Zhiming; Cao, Shiyao; Liu, Yichong; Zhang, Xiaohui; Zhang, Yue

    2016-01-13

    A CdS/reduced graphene oxide (RGO)/ZnO nanowire array (NWAs) heterostructure is designed, which exhibits enhanced photoelectrochemical (PEC) activity compared to pure ZnO, RGO/ZnO, and CdS/ZnO. The enhancement can be attributed to the synergistic effect of the high electron mobility of ordered 1D ZnO NWAs, extended visible-light absorption of CdS nanocrystals, and the formed type II band alignment between them. Moreover, the incorporation of RGO further promotes the charge carrier separation and transfer process due to its excellent charge collection and shuttling characteristics. Subsequently, the CdS/RGO/ZnO heterostructure is successfully utilized for the PEC bioanalysis of glutathione at 0 V (vs Ag/AgCl). The self-powered device demonstrates satisfactory sensing performance with rapid response, a wide detection range from 0.05 mm to 1 mm, an acceptable detection limit of 10 μm, as well as certain selectivity, reproducibility, and stability. Therefore, the CdS/RGO/ZnO heterostructure has opened up a promising channel for the development of PEC biosensors. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  17. Band offsets engineering at Cd_x Zn_1_−_x S/Cu_2ZnSnS_4 heterointerface

    International Nuclear Information System (INIS)

    Bao Wujisiguleng; Qiu Fang-Yuan; Sachuronggui

    2016-01-01

    Cd_1_−_x Zn_x S/Cu_2ZnSnS_4 (CZTS)-based thin film solar cells usually use CdS as a buffer layer, but due to its smaller band gap (2.4 eV), CdS film has been replaced with higher band gap materials. The cadmium zinc sulfide (CdZnS) ternary compound has a higher band gap than other compounds, which leads to a decrease in window absorption loss. In this paper, the band offsets at Cd_1_−_x Zn_x S/Cu_2ZnSnS_4 (CZTS) heterointerface are calculated by the first-principles, density-functional and pseudopotential method. The band offsets at Cd_1_−_x Zn_x S/CZTS heterointerface are tuned by controlling the composition of Zn in Cd_1_−_x Zn_x S alloy, the calculated valence band offsets are small, which is consistent with the common-anion rule. The favorable heterointerface of type-I with a moderate barrier height (< 0.3 eV) can be obtained by controlling the composition of Zn in Cd_1_−_x Zn_x S alloy between 0.25 and 0.375. (paper)

  18. Synthesis, optical properties and efficient photocatalytic activity of CdO/ZnO hybrid nanocomposite

    Science.gov (United States)

    Reddy, Ch Venkata; Babu, B.; Shim, Jaesool

    2018-01-01

    Pure CdO, ZnO and CdO/ZnO hybrid nanocomposite photocatalyst were synthesized using simple co-precipitation technique and studied in detail. The synthesized photocatalysts were characterized using several measurements such as X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), surface analysis (BET), diffuse reflectance UV-vis spectroscopy, X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, FT-IR, TG-DTA and photoluminescence (PL). The XRD results revealed that the hexagonal and cubic crystal structure of CdO and ZnO nanoparticles. The optical response for the composite showed the presence of separate absorption signature for CdO and ZnO in the visible region at about 510 nm and 360 nm respectively. The CdO/ZnO hybrid nanocomposite photocatalyst exhibited enhanced photocatalytic degradation activity compared to pristine CdO and ZnO. The enhanced photocatalytic activity may be due to the higher specific surface area and significantly reduced the electron-hole recombination rate.

  19. Nonlinear optical properties of hybridized CdS/ZnS-PVP sols

    Science.gov (United States)

    Kulagina, A. S.; Evstropiev, S. K.; Khrebtov, A. I.

    2017-11-01

    Hybrid composites of CdS-core ZnS-shell nanoparticles embedded in polyvinylpyrrolidone (PVP) matrixes have been prepared and characterized. Cadmium sulfide (CdS) nanocrystals were grown in water-propanol-2 solutions containing high-molecular (Ms=1300000) polyvinylpyrrolidone (PVP) at room temperature using cadmium nitrate and sodium sulfide as the cadmium and sulfur sources, respectively. The CdS/ZnS-PVP suspensions have promising optical properties for nanocomposite films based on. Nonlinear optical properties of diluted CdS/ZnS sols were studied at 532 nm and 5 ns laser pulses by using the Z-scan technique. Dependence of the nonlinear-optical coefficients on the CdS weight has been obtained.

  20. Quenching of coumarin emission by CdSe and CdSe/ZnS quantum dots: Implications for fluorescence reporting

    International Nuclear Information System (INIS)

    Baride, Aravind; Engebretson, Daniel; Berry, Mary T.; Stanley May, P.

    2013-01-01

    The photoinduced release of highly fluorescent 7-diethylamino coumarin (7DEAC) from CdSe quantum dots (QD) modified with a thiocinnamate ligand (11-mercapto undecyl-E-3-(4-(N,N-diethylamino)-2-hydroxy phenyl) propenoate, [4DEATC]) has been previously described. Coumarin fluorescence was used to ‘report’ the photochemical reaction. The current study quantifies the quenching effect of the QDs on the coumarin emission in this system. A systematic study is presented on the quenching of 7DEAC by CdSe and CdSe/ZnS quantum dots capped with 2-[2-(2-methoxyethoxy)ethoxy] ethanethiol (PEG-thiol). A new method for the functionalization of CdSe and CdSe/ZnS QDs with PEG-thiol was developed, which does not require isolation of the as-synthesized QDs. Stern–Volmer analysis was applied to quantify the effect of the PEG-CdSe and PEG-CdSe/ZnS on 7DEAC emission. The Stern–Volmer constant, K SV , was shown to be inversely proportional to temperature for quenching by PEG-CdSe, and the fluorescence lifetime of 7DEAC was shown to be independent of PEG-CdSe concentration. Room-temperature K SV values were similar for the PEG-CdSe and PEG-CdSe/ZnS quenchers. The large magnitude of K SV , the temperature dependence of K SV , the lifetime data, and the similarity of K SV values for the core and core–shell QD quenchers are all consistent with a static quenching mechanism. Assuming a static quenching mechanism, the temperature dependence of the coumarin-QD binding constant, K b , was used to estimate the ΔH and ΔS for the binding process. -- Highlights: • Quenching of a coumarin derivative by CdSe and CdSe/ZnS quantum dots is demonstrated • Stern–Volmer analysis is performed as a function of temperature • Fluorescence lifetime analysis was used to support Stern–Volmer analysis • Data overwhelmingly support quenching via a Static Mechanism • Quenching of coumarin by quantum dots is significant and must be considered in any release and report scheme

  1. The response of metallothionein and malondialdehyde after exclusive and combined Cd/Zn exposure in the crab Sinopotamon henanense.

    Directory of Open Access Journals (Sweden)

    Yingjun Li

    Full Text Available The purpose of this paper is to show the interactions of Cd and Zn in the freshwater crab Sinopotamon henanense through metallothionein (MT and malondialdehyde (MDA level measurements. Laboratory acclimated S.henanense were exposed to Cd (50 µg/L, 100 µg/L, 500 µg/L , and Zn (100 µg/L, 1000 µg/L alone and in combined treatments (100 µg/L Zn+50 µg/L Cd, 100 µg/L Zn+100 µg/L Cd, 100 µg/L Zn+500 µg/L Cd, 1000 µg/L Zn+50 µg/L Cd, 1000 µg/L Zn+100 µg/L Cd, 1000 µg/L Zn+500 µg/L Cd for 7, 14, 21, 28, 35 days. The results demonstrated that the MDA contents increased with exposure time and dose and showed time- and dose-dependence in both gills and hepatopancreas of S.henanense after single Cd exposure, while the changes of MDA levels were not significant with single Zn exposure. The MDA levels decreased when the crabs were exposed to metal mixtures compared to Cd exposure alone, indicating that Zn mediated the cellular toxicity of Cd. MT contents increased after single Cd exposure and also showed a time- and dose-dependence, in a tissue-specific way. Zn showed a limited ability of MT induction both in gills and hepatopancreas of S.henanense. The MT contents represented not a simple addition of single metal exposures but were enhanced at a higher concentration of Zn combined with different Cd concentrations compared to single metal exposure. Whether MT can be used as a biomarker for complex field conditions need to be considered cautiously since different induction patterns of MT were found among single Zn, Cd and combined groups. It is suggested that several biomarkers together as a suite should be used in the monitoring of heavy metal pollution in the aquatic environment.

  2. 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.

  3. Removal and Preconcentration of Pb (II and Cd (II by Zero-Valent Iron Nanoparticles in Contaminated Water

    Directory of Open Access Journals (Sweden)

    Shiralipour

    2015-04-01

    Full Text Available Background Lead (Pb and cadmium (Cd are two of the hazardous metals in the environment due to their acute and chronic effects on human health. Zero-valent iron nanoparticles (ZVINPs are one of the adsorbents proposed as an efficient adsorbent for Pb and Cd. Objectives This study evaluated the quantitative removal efficiency of Pb and Cd ions from contaminated water by ZVINPs. In addition, the capability of ZVINPs as a solid phase extractor for preconcentration and determination of Pb and Cd was investigated. Materials and Methods Four samples, each from different water sources like Well water (Shushtar, Iran, Karoon River (Ahvaz, Iran, Caspian Sea (northern Iran and Persian Gulf (southern Iran were collected. Results The elapsed time for quantitative removal of both Pb and Cd ions was two minutes. This method is applicable in a widespread range of pH and relatively high concentrations of electrolyte (NaCl for the efficient removal (> 99% of Pb and Cd ions in water samples. The adsorption of Pb and Cd ions on ZVINPs was well followed by the Langmuir model. The maximum adsorption amounts of Pb and Cd ions on ZVINPs were 96.5 and 58.3 mg/g, respectively. Limits of detection (LODs of the method for lead and cadmium ions were 0.015 and 0.002 mg/L, respectively. The relative standard deviations for ten replicate determinations (Pb2+ 0.3 mg/L, Cd2+ 0.03 mg/L were below 5%. The enrichment factors were more than 16 and 14 for Pb2+ and Cd2+, respectively. Conclusions The proposed method is simple, fast, cost-effective and safe for the environment.

  4. Synthesis and optical characterization of single phased ZnS:Mn²⁺/CdS core-shell nanoparticles.

    Science.gov (United States)

    Murugadoss, G; Ramasamy, V

    2012-07-01

    Uncoated ZnS, ZnS:Mn(2+), CdS and different thickness of CdS coated ZnS:Mn(2+) core-shell nanoparticles were successfully synthesized by a simple chemical method in an air atmosphere. X-ray diffraction (XRD) and transmission electron microscopy (TEM) techniques were used to characterize the uncoated and the novel ZnS:Mn(2+)/CdS core-shell nanoparticles. The results show that the size of the ZnS:Mn(2+)/CdS core-shell nanoparticles is less than the bare ZnS:Mn(2+). The PL study of ZnS:Mn(2+)/CdS core-shell nanoparticles shows an enhanced intensity than ZnS:Mn(2+). The coating of CdS layer over ZnS:Mn(2+) tuned the PL emission in the visible region. Addition of cadmium acetate (Cd 4 and 5M) in ZnS:Mn(2+) shows a distinct PL peak centered at 542 nm. The presence of Mn(2+) ions in ZnS lattice and the growth of the CdS on ZnS:Mn(2+) nanoparticles were confirmed by the ESR spectra. Copyright © 2012 Elsevier B.V. All rights reserved.

  5. Synthesis and characterization of optic properties of CdSe and CdSe/ZnS quantum dots

    Directory of Open Access Journals (Sweden)

    Brayan Stiven Gómez Piñeros

    2018-01-01

    Full Text Available CdSe and CdSe/ZnS (core/shell quantum dots with oleic acid as stabilizing agent in organic medium were prepared and their optical properties were examined. For CdSe synthesis, the influence of O2 in the growth kinetics of quantum dots was determined. In the first 90 s, the nanocrystals growth was 1.6 higher in presence of O2 than when reaction was carried out in N2 atmosphere. However, the growth rate with O2 is not favorable because the nanocrystal optical properties were affected: wider absorption band and lower fluorescence that those obtained in inert atmosphere. Properties of CdSe nanocrystals synthesized in inert atmosphere were intensified with 10% of monolayer. For a core with 2.5 nm diameter, the fluorescence quantum yield (ΦFl in the green region increased from 5.5% to 42.3%. In this work, a low Zn2+ (diethylzinc precursor concentration was used to produce a. The synthesis process of CdSe / ZnS nanocrystals developed with low concentration of Zn2+ and an excess of S2- can be used to obtain materials with excellent photoluminescent properties for applications such as biomarkers, sensors, catalysis, and solar cells.

  6. 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.

  7. 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.

  8. Use of inorganic and organic wastes for in situ immobilisation of Pb and Zn in a contaminated alkaline soil.

    Science.gov (United States)

    Zhou, Y-F; Haynes, R J; Naidu, R

    2012-05-01

    This study aims to examine whether addition of immobilising agents to a sandy, alkaline (pH = 8.1) soil, which had been contaminated with Pb and Zn by airborne particles from a Pb/Zn smelter, would substantially reduce metal bioavailability. The effectiveness of five waste materials (blast furnace (BF) slag, alum water treatment (WT) sludge, red mud, sugar mill mud and green waste compost) as metal immobilising agents was evaluated by incubating them with a contaminated soil for a period of 12 months at rates of 5% and 10% (w/w), after which, Rhodes grass was grown in the soils in a greenhouse study. Additions of WT sludge, BF slag and red mud reduced CaCl(2), CH(3)COOH, HCl and EDTA-extractable Zn but compost and mill mud had no appreciable immobilising effects. Additions of all amendments reduced levels of CaCl(2), CH(3)COOH and HCl-extractable Pb although concentrations of EDTA-extractable Pb remained unchanged. A sequential extraction procedure showed that additions of mill mud and compost increased the percentage of total Pb and Zn present in the oxidisable fraction whilst additions of the other materials increased the percentage present in the residual fraction. Rhodes grass yields were promoted greatly by additions of red mud, compost and particularly mill mud, and yields were negatively correlated with tissue Pb concentrations and extractable Pb. Red mud was the most effective material for lowering extractable Pb and Zn levels simultaneously while mill mud and compost were notably effective for Pb. A field evaluation in the study area is justified.

  9. Thin Film CdZnTe Detector Arrays for Digital Mammography

    National Research Council Canada - National Science Library

    Sudharsanan, Rengarajan

    1999-01-01

    ...) directly on thin-film transistor (TFT) active matrix arrays for image readout. CdTe and CdZnTe have the potential to meet the requirements for digital mammography due to their high x-ray absorption, large band gap and good carrier transport...

  10. Thin Film CdZnTe Detector Arrays for Digital Mammography

    National Research Council Canada - National Science Library

    Kalkhoran, Nader

    2001-01-01

    ...) directly on thin-film transistor (TFT) active matrix arrays for image readout. CdTe and CdZnTe have the potential to meet the requirements for digital mammography due to their high x-ray absorption, large bandgap and good carrier transport...

  11. Synthesis and spectroscopic study of high quality alloy Cd Zn S ...

    Indian Academy of Sciences (India)

    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 ...

  12. Partially decomposed PVP as a surface modification of ZnO, CdO ...

    Indian Academy of Sciences (India)

    Infrared spectra confirmed the PVP–metal complexation and partial decomposition of the polymer. ... and morphology impact; further, P-CdS induced 71% antibiotic degradation after 10 h of illumination with visible light compared with only 48% for P-ZnS, 29% for P-ZdO and 20% for P-CdO due to improved light absorption.

  13. Influence of electrical conductivity on the phytoremediation of contaminated soils to Cd 2+ and Zn 2+

    Directory of Open Access Journals (Sweden)

    Maryam Salimi

    2012-01-01

    Conclusions: Results showed that high EC levels of irrigation water increased Cd accumulation and decreased Zn accumulation in the shoots. The presence of high EC levels in irrigation water negatively affected biomass production by plants. Chlorine ion (Cl- had a positive influence on Cd accumulation in the harvestable parts of the plant.

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

    DEFF Research Database (Denmark)

    Gindele, F.; Woggon, Ulrike; Langbein, Wolfgang Werner

    1999-01-01

    The optical properties of CdSe nanostructures grown by migration-enhanced epitaxy of CdSe on ZnSe are studied by time-, energy-, and temperature-dependent photoluminescence and excitation spectroscopy, as well as by polarization-dependent four-wave mixing and two-photon absorption experiments...

  15. The crystal structure of kudriavite, (Cd,Pb)Bi2S4

    DEFF Research Database (Denmark)

    Balic Zunic, Tonci; Makovicky, Emil

    2007-01-01

    The crystal structure of kudriavite, (Cd,Pb)Bi2S4, a new mineral species, was solved from single-crystal X-ray-diffraction data and refi ned to R = 4.9% (4.3% for a model with split mixed-cation sites). Lattice parameters are a 13.095(1), b 4.0032(3), c 14.711(1) Å, 115.59(1)°, V 695.6(1) Å3...... chemical Cd ¿ Pb and Bi ¿ In substitutions are, according to the crystal-chemical analysis, structurally limited to Bi-containing sites. They are distributed predominantly in the boundary coordinations of the type-I slabs, and the central octahedra of the type-II slabs, with Pb preferentially entering....... The structure is equivalent to that of synthetic CdBi2S4, space group C2/m, Z = 4, and represents a pavonite homologue, N = 3. It is built of three-octahedron-thick columns of (311)PbS-like slabs combined by "unitcell twinning" in a quasi-mirror-glide succession. The slabs, which are intrinsically of the same...

  16. Photoelectric converters on Cr/x/Te/y/-Zn/x/Cd/1-x/S heterojunction

    Science.gov (United States)

    Konstantinova, E. M.; Stratieva, N. R.

    The layer properties of Zn(x)Cd(1-x)S(x) are are investigated, and the use of these materials in heterojunction photocells and convertors is evaluated. Results show that the calculated lattice mismatch of the semiconductor decreases with an increase of the Zn content in the solid solutions. A Cr(x)Te(y)-Zn(x)Cd(1-x)S heterojunction is fabricated and is found to have an increase in efficiency of 1% when the open-circuit voltage is raised by about 150 mV and the other parameters are held constant. The open-circuit voltage for photocells based on Cr(x)Te(y) and Zn(x)Cd(1-x)S, with x = 0.05-0.3, is measured under 80 mW/sq cm illumination, and is shown to be lower than the open circuit voltages for Cr(x)Te(y)-Zn(x) Cd(1-x)S samples. In addition, the I-V characteristics of the samples are determined. It is concluded that the wide spectral sensitivity, the high open-circuit voltage, as well as satisfactory conversion efficiencies, of solar cells based on Cr(x)Te(y)-Zn(x)Cd(1-x)S will allow the development of solar energy convertors with improved parameters.

  17. Changes in heavy metal bioavailability and speciation from a Pb-Zn mining soil amended with biochars from co-pyrolysis of rice straw and swine manure.

    Science.gov (United States)

    Meng, Jun; Tao, Mengming; Wang, Lili; Liu, Xingmei; Xu, Jianming

    2018-03-22

    Biochar has been utilized as a good amendment to immobilize heavy metals in contaminated soils. However, the effectiveness of biochar in metal immobilization depends on biochar properties and metal species. In this study, the biochars produced from co-pyrolysis of rice straw with swine manure at 400°C were investigated to evaluate their effects on bioavailability and chemical speciation of four heavy metals (Cd, Cu, Pb and Zn) in a Pb-Zn contaminated soil through incubation experiment. Results showed that co-pyrolysis process significantly change the yield, ash content, pH, and electrical conductivity (EC) of the blended biochars compared with the single straw/manure biochar. The addition of these biochars significantly increased the soil pH, EC, and dissolved organic carbon (DOC) concentrations. The addition of biochars at a rate of 3% significantly reduced the CaCl 2 -extractable metal concentrations in the order of Pb>Cu>Zn>Cd. The exchangeable heavy metals decreased in all the biochar-amended soils whereas the carbonate-bound metal speciation increased. The increase in soil pH and the decrease in the CaCl 2 extractable metals indicated that these amendments can directly transform the highly availability metal speciation to the stable speciation in soils. In conclusion, biochar derived from co-pyrolysis of rice straw with swine manure at a mass ratio of 3:1 could most effectively immobilize the heavy metals in the soil. Copyright © 2018 Elsevier B.V. All rights reserved.

  18. A Diffusive Gradient-in-Thin-Film Technique for Evaluation of the Bioavailability of Cd in Soil Contaminated with Cd and Pb

    Directory of Open Access Journals (Sweden)

    Peifang Wang

    2016-06-01

    Full Text Available Management of heavy metal contamination requires accurate information about the distribution of bioavailable fractions, and about exchange between the solid and solution phases. In this study, we employed diffusive gradients in thin-films (DGT and traditional chemical extraction methods (soil solution, HOAc, EDTA, CaCl2, and NaOAc to determine the Cd bioavailability in Cd-contaminated soil with the addition of Pb. Two typical terrestrial species (wheat, Bainong AK58; maize, Zhengdan 958 were selected as the accumulation plants. The results showed that the added Pb may enhance the efficiency of Cd phytoextraction which is indicated by the increasing concentration of Cd accumulating in the plant tissues. The DGT-measured Cd concentrations and all the selected traditional extractants measured Cd concentrations all increased with increasing concentration of the addition Pb which were similar to the change trends of the accumulated Cd concentrations in plant tissues. Moreover, the Pearson regression coefficients between the different indicators obtained Cd concentrations and plants uptake Cd concentrations were further indicated significant correlations (p < 0.01. However, the values of Pearson regression coefficients showed the merits of DGT, CaCl2, and Csol over the other three methods. Consequently, the in situ measurement of DGT and the ex situ traditional methods could all reflect the inhibition effects between Cd and Pb. Due to the feature of dynamic measurements of DGT, it could be a robust tool to predict Cd bioavaiability in complex contaminated soil.

  19. Facile synthesis of monodisperse ZnS capped CdS nanocrystals exhibiting efficient blue emission

    Directory of Open Access Journals (Sweden)

    Reiss Peter

    2006-01-01

    Full Text Available AbstractA new method for the capping of colloidal CdS nanocrystals with ZnS shells is presented. A combination of the monomolecular precursor zinc ethylxanthate (Zn(ex2 and zinc stearate was used to replace hazardous organometallic reagents usually applied in this procedure, i.e. bis(trimethylsilyl sulfide and diethylzinc. Its simple preparation, air-stability and low decomposition temperature of 150 °C make Zn(ex2a very suitable source for the ZnS shell growth. With this precursor, highly luminescent CdS/ZnS core/shell nanocrystals (Q.Y. 35–45%, exhibiting narrow emission linewidths of 15–18 nm (FWHM in the blue spectral region, can reproducibly be obtained.

  20. 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. Copyright © 2013. Published by Elsevier Masson SAS.

  1. Facile synthesis and photocatalytic properties of ZnO core/ZnS-CdS solid solution shell nanorods grown vertically on reductive graphene oxide.

    Science.gov (United States)

    Xu, Jimeng; Sang, Huanxin; Wang, Xitao; Wang, Kang

    2015-05-28

    In the present study, ZnS-CdS solid solution sensitized ZnO nanorods were anchored on graphene sheets by combining a hydrothermal process and ion exchange technique, and the significant influence of CdS content in the shell on photo absorption and photocatalytic performance were investigated. Electron microscopic images reveal that the as-prepared nanocomposites display a sandwich-like 3D structure, consisting of ZnO nanorods with a ZnxCd1-xS or CdS shell grown vertically on both sides of the graphene sheets. UV/Vis DRS shows that the solid solution sensitized nanocomposites have enhanced visible light absorption and also exhibited a red-shift of the band-edge as compared to RGO/ZnO and RGO/ZnO@ZnS. Fluorescence emission spectra indicate that the deposition of CdS on the shell with an appropriate CdS/ZnS ratio and the incorporation of graphene causes improved charge separation. The photocatalytic experiments demonstrate that the RGO/ZnO@ZnxCd1-xS nanocomposites possess much higher photocatalytic activity for H2 evolution than the RGO/ZnO nanorods and RGO/ZnO@ZnS core/shell nanorods. Under the irradiation of a 300 W Xe lamp, the highest photocatalytic hydrogen production rate of 1865 μmol h(-1) g(-1) is observed over the RGO/ZnO@Zn0.6Zn0.4S sample, which is about 2.1 and 1.4 times more active than RGO/ZnO and RGO/ZnO@ZnS, respectively. Under the irradiation of visible light (>420 nm), the RGO/ZnO and RGO/ZnO@ZnS nanorods are barely active, whereas RGO/ZnO@Zn0.6Zn0.4S displays a hydrogen production rate of 160 μmol h(-1) g(-1). The highly improved performance of the composites can be ascribed to the increased light absorption and efficient charge separation.

  2. MODEL ADSORPSI TIMBAL (PB DAN SENG (ZN DALAM SISTEM AIR-SEDIMEN DI WADUK RIAM KANAN KALIMANTAN SELATAN

    Directory of Open Access Journals (Sweden)

    Chatimatun Nisa

    2013-04-01

    Full Text Available Heavy metals are often considered as main contaminant in water pollution and its highly dangerous for living organisms in the contaminated area. The aim of this research is to predict the movement pattern of Pb and Zn metal ions from water onto sediment in the Riam Kanan Reservoir, Aranio Sub-district, Banjar District. In addition, this study is expected to give information on the initial condition of Riam Kanan reservoir; dynamics; and the fate of Pb and Zn ions from upstream to downstream. The samples were analysed using AAS (Atomic Absorption Spectrophotometer based on the Indonesian National Standard (SNI. Result of laboratory analysis showed that in the water, contents of metal Pb were 0.0494 ppm – 0.2582 ppm, Zn 0.0002 ppm – 0.0370 ppm. In the sediment, contents of Pb were 0.8311 mg/kg – 21.1756 mg/kg and Zn 3.3778 mg/kg – 28.3522 mg/kg. Based on the experimental data, it was found that the displacement of Pb and Zn onto sediment complies with Langmuir adsorption model where the determination coefficient (R2 were 0.8167 and 0.8801 respectively.

  3. Did a whole-crustal hydrothermal system generate the Irish Zn-Pb orefield?

    Science.gov (United States)

    Daly, J. Stephen; Badenszki, Eszter; Chew, David; Kronz, Andreas; O'Rourke, Helen; Whitehouse, Martin; Menuge, Julian; van den Berg, Riana

    2016-04-01

    Current models[1] for the genesis of the giant Irish Carboniferous-hosted Zn-Pb orefield propose shallow (700°C) metamorphism and melting during the Acadian orogeny at ~390Ma and during separate episodes of extension at ~ 381-373Ma and ~362Ma. Sm-Nd garnet dating shows that the lower crust remained hot or was re-heated to ~600°C at ~341Ma during Lower Carboniferous volcanism, also associated with extension and, in part, coincident with the mineralization[1]. Isotopic data from the xenoliths correspond closely to Sr and Nd isotopic analyses of gangue calcite[8] and galena Pb[9] isotopic data from the major ore deposits. While Zn contents of the xenoliths permit them to be metal sources, their mineralogy and texture provide an enriched template and a plausible extraction mechanism. In situ analyses of modally-abundant biotite and garnet show significant enrichment in Zn (and other relevant metals) as well as order of magnitude depletion of Zn during retrograde alteration, providing a metal-release mechanism and pointing to a hydrothermal fluid system operating at least to depths of ~ 25km. References [1] Wilkinson, J.J. & Hitzman, M.W. 2015. The Irish Pb-Zn orefield: The view from 2014. In: Archibald, S.M. and Piercey, S.J. (eds) Current Perspectives on Zinc deposits. Irish Association for Economic Geology, pp. 59-72.; [2] Davidheiser-Kroll, B., Stuart, F.M. & Boyce, A.J. 2014. Mineralium Deposita, 49, 547-553; [3] Elliott, H. 2015. Unpublished PhD thesis, University of Southampton; [4] Hnatyshin, D., Creaser, R.A., Wilkinson, J.J. & Gleeson, S.A. 2015. Geology, 43, 143-146; [5] McCusker, J. & Reed, C. 2013. Mineralium Deposita, 48, 687-695; [6] Van den Berg, R., Daly, J.S. & Salisbury, M.H. 2005. Tectonophysics, 407(1-2), 81-99; [7] Hauser, F., O'Reilly, B.M., Readman, P.W., Daly, J. S. & Van den Berg, R. 2008. Geophysical Journal International 175, 1254-1272; [8] Walshaw, R.D., Menuge, J.F. & Tyrrell, S. 2006. Mineralium Deposita, 41, 803-819; [9] Everett, C

  4. Continuous biosorption of Pb/Cu and Pb/Cd in fixed-bed column using algae Gelidium and granulated agar extraction algal waste

    Energy Technology Data Exchange (ETDEWEB)

    Vilar, Vitor J.P. [LSRE-Laboratory of Separation and Reaction Engineering, Departamento de Engenharia Quimica, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto (Portugal)], E-mail: vilar@fe.up.pt; Loureiro, Jose M. [LSRE-Laboratory of Separation and Reaction Engineering, Departamento de Engenharia Quimica, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto (Portugal)], E-mail: loureiro@fe.up.pt; Botelho, Cidalia M.S. [LSRE-Laboratory of Separation and Reaction Engineering, Departamento de Engenharia Quimica, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto (Portugal)], E-mail: cbotelho@fe.up.pt; Boaventura, Rui A.R. [LSRE-Laboratory of Separation and Reaction Engineering, Departamento de Engenharia Quimica, Faculdade de Engenharia da Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto (Portugal)], E-mail: bventura@fe.up.pt

    2008-06-15

    Continuous metal ions biosorption from Pb/Cu and Pb/Cd solutions onto seaweed Gelidium sesquipedale and a composite material prepared from an industrial algal waste was performed in a packed bed column. A binary Langmuir equation describes well the equilibrium data and indicates a good adsorption capacity. In the sorption process, Cd and Cu break through the column faster than Pb due to its lower affinity for the biosorbent. An overshoot in the outlet Cd concentration was observed and explained by competitive adsorption between Pb and Cd, whereby the higher Pb affinity for the biosorbent displaces bound Cd ions. A small overshoot happens for Cu adsorption in the presence of Pb ions. Desorption using 0.1 M HNO{sub 3} as eluant, was 100% effective. A mass transfer model for the adsorption and desorption processes, considering an external and intraparticle film resistance, adequately simulates the column performance. A binary Langmuir equation was used to describe equilibrium for the saturation process and a mass action law for the desorption process. Elution process is defined as an ion exchange mechanism, between protons and metal ions.

  5. Continuous biosorption of Pb/Cu and Pb/Cd in fixed-bed column using algae Gelidium and granulated agar extraction algal waste.

    Science.gov (United States)

    Vilar, Vítor J P; Loureiro, José M; Botelho, Cidália M S; Boaventura, Rui A R

    2008-06-15

    Continuous metal ions biosorption from Pb/Cu and Pb/Cd solutions onto seaweed Gelidium sesquipedale and a composite material prepared from an industrial algal waste was performed in a packed bed column. A binary Langmuir equation describes well the equilibrium data and indicates a good adsorption capacity. In the sorption process, Cd and Cu break through the column faster than Pb due to its lower affinity for the biosorbent. An overshoot in the outlet Cd concentration was observed and explained by competitive adsorption between Pb and Cd, whereby the higher Pb affinity for the biosorbent displaces bound Cd ions. A small overshoot happens for Cu adsorption in the presence of Pb ions. Desorption using 0.1 M HNO3 as eluant, was 100% effective. A mass transfer model for the adsorption and desorption processes, considering an external and intraparticle film resistance, adequately simulates the column performance. A binary Langmuir equation was used to describe equilibrium for the saturation process and a mass action law for the desorption process. Elution process is defined as an ion exchange mechanism, between protons and metal ions.

  6. U-Pb geochronology, geochemistry, and H-O-S-Pb isotopic compositions of the Leqingla and Xin'gaguo skarn Pb-Zn polymetallic deposits, Tibet, China

    Science.gov (United States)

    Wang, Liqiang; Cheng, Wenbin; Tang, Juxing; Kang, Haoran; Zhang, Yan; Li, Zhuang

    2016-01-01

    The Leqingla and Xin'gaguo deposits are two representative skarn Pb-Zn polymetallic deposits of the Gangdese Pb-Zn polymetallic belt, Tibet, China. LA-ICP-MS zircon U-Pb dating of the mineralization-related biotite granites from both the Leqingla and Xin'gaguo deposits yielded weighted mean ages of 60.8 Ma and 56.5 Ma, respectively, which can be inferred as their mineralization ages. The Leqingla biotite granite is characterized by high Al2O3, total Fe, Na2O, and low K2O. In comparison, the Xin'gaguo biotite granite is characterized by relative higher K2O but lower Al2O3, total Fe, and Na2O. Geochemical and mineralogical characteristics indicate that the Leqingla and Xin'gaguo biotite granites are calc-alkaline I-type granite and High K calc-alkaline I-type granite, respectively. Both the Leqingla and Xin'gaguo biotite granites are enrichment in LREE and LILEs and depletion in HFSEs, and they were formed at the India-Asia collision stage. δ18O and δD values for the Leqingla and Xin'gaguo deposits are -8.8‰ to 5.3‰ and -140.4‰ to -90.1‰, -4.5‰ to 7.0‰ and -117.3‰ to -81.0‰, respectively, indicating magma fluids mixed with meteoric water in ore-forming fluids. δ34S values (-11.6‰ to -0.3‰) of ore sulfides from the Leqingla deposit show characteristics of biogenetic sulfur isotope compositions, suggesting sulfur for the Leqingla deposit were sourced from wall rocks of the Mengla and Luobadui Formation, which are rich in organic materials. δ34S values of ore sulfides from the Xin'gaguo deposits show bimodal distribution (-5.0‰ to -1.6‰ and 1.6-2.1‰), indicating sulfur in the Xin'gaguo deposit were derived from both wall rocks and magma. In the Leqingla deposit, most ore sulfides have the similar Pb isotopic compositions with that of the mineralization-related biotite granite, suggesting the biotite granite supplied most of the ore-forming metals. Pb isotopic compositions of ore sulfides and Hf isotopic compositions of biotite granite show

  7. Comprehensive study of growth mechanism and properties of low Zn content Cd{sub 1-x}Zn{sub x}S thin films by chemical bath

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez, Carlos Anibal [Multidisciplinary Research Institute in Science and Technology, Ineergias, University of La Serena (Chile); Sandoval-Paz, Myrna Guadalupe; Saavedra, Renato; De la Carrera, Francisco [Department of Physics, Faculty of Physical and Mathematical Sciences, University of Concepcion (Chile); Trejo-Cruz, Cuauhthemoc [Department of Physics, Faculty of Sciences, University of Biobio, Concepcion (Chile); Aragon, Luis E.; Sirena, Martin [Centro Atomico Bariloche & Instituto Balseiro, CNEA & Univ. Nac. de Cuyo, Bariloche, Rio Negro (Argentina); Delplancke, Marie-Paule [4MAT, Universite Libre de Bruxelles, Brussels (Belgium); Carrasco, Claudia [Department of Materials Engineering, Faculty of Engineering, University of Concepcion (Chile)

    2016-11-15

    Cd{sub 1-x}Zn{sub x}S thin films have been studied extensively as window layers for solar cell applications. However, a mismatch between the Cd{sub 1-x}Zn{sub x}S and copper-indium-gallium-selenide absorber layers increases with Zn film concentration, which reduces the device efficiency. In this work, Cd{sub 1-x}Zn{sub x}S thin films with low Zn concentrations were analyzed. The effect of the addition of different molar Zn concentrations to the reaction mixture on the growth mechanism of Cd{sub 1-x}Zn{sub x}S thin films and the influence of these mechanisms on structural, optical and morphological properties of the films has been studied. Cd{sub 1-x}Zn{sub x}S thin films were synthesized by chemical bath deposition using an ammonia-free alkaline solution. Microstructural analysis by X-ray diffraction showed that all deposited films grew with hexagonal structure and crystallite sizes decreased as the Zn concentration in the film increased. Optical measurements indicated a high optical transmission between 75% and 90% for wavelengths above the absorption edge. Band gap value increased from 2.48 eV to 2.62 eV, and the refractive index values for Cd{sub 1-x}Zn{sub x}S thin films decreased as the Zn increased. These changes in films and properties are related to a modification in growth mechanism of the Cd{sub 1-x}Zn{sub x}S thin films, with the influence of Zn(OH){sub 2} formation being more important as Zn in solution increases. (author)

  8. 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

  9. Timing performance of pixellated CdZnTe detectors

    International Nuclear Information System (INIS)

    Amrami, R.; Shami, G.; Hefetz, Y.; Pansky, A.; Wainer, N.

    1999-01-01

    Recently introduced nuclear medicine cameras in which Positron Emission Tomography (PET) and the traditional Single Photon Emission Computerized Tomography (SPECT), are combined opened new horizon for the nuclear medicine field These systems applying NaI(Tl) scintillation detectors we very well tested and mailable for some time in the medical imaging field However the traditional NaI(Tl) cameras, optimized for low energy radiation imaging, suffer some severe limitations. The relatively low density (3.67 g/cm 2 ) of NaI(Tl) limits the sensitivity. By incarcerating the NaI(Tl) thickness, the spatial resolution decreases. The long decay time (230 nsec) of the light emitted in NaI(Tl) restricts the the use of coincidence technique , as well as the count rate. In recent years CdZn Te (CZT) detectors are studied for the purpose of SPECT nuclear medical radiation imaging in the form of pixellated and microstrip detectors. CZT detector can served as a good candidate for replacing NaI(Tl) for PET and SPECT imaging due to their relatively high stopping power (density = (6.0 g/im 3 , high Z(48, 30, 52)) and their high count rate capability. Unfortunately there are several difficulties in PET application due to the difficulty in manufacturing thick crystals, registration of the full energy deposited in several pixels and their timing capabilities. The latter is due to large ballistic signal variation induced. This variations caused by the pulse shape, which is composed of two main components, the electron and the hole. The electrons travel about ten times faster than the holes. A photon absorbed clear the cathode plane will cause a large and fast signal induced by the electron and a small and slow signal induced due to the holes. Photons absorbed near the anode plane will induce the opposite signals. The distribution of photon absorption depth in the crystal causes signal splits over a number of pixels, due to the well-known 'small pixel effect'. The different pulses slope

  10. ZnO/CdS bi-layer nanostructures photoelectrode for dye-sensitized solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Dalal, Paresh V., E-mail: paresh10dalal@gmail.com [Physics Research Lab, Shri V. S. Naik Arts, Commerce and Science College, Raver-425508 (M. S.) (India); Deshpande, Milind P., E-mail: vishwadeshpande@yahoo.co.in [Department of Physics, Sardar Patel University, Vallabh Vidyanagar-388120 (Gujarat) (India); Solanki, Bharat G., E-mail: bhrt.solanki17@gmail.com; Soni, Saurabh S., E-mail: soni-b21@yahoo.co.in [Department of Chemistry, Sardar Patel University, Vallabh Vidyanagar-388120 (Gujarat) (India)

    2016-05-06

    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 (< 373K) is described. The different preparative parameters such as deposition time, bath temperature, concentration of precursor solution and, pH of the bath etc. were optimized. Nanograined ZnO was deposited on FTO 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.

  11. Mobility of Pb, Zn, Cu and As in disturbed forest soils affected by acid rain.

    Science.gov (United States)

    Kochergina, Yulia V; Udatný, Martin; Penížek, Vít; Mihaljevič, Martin

    2017-10-18

    Early efforts at remediation of contaminated soils involve overturn or removal of the uppermost soil horizons. We find that such disruption is counterproductive, as it actually increases the mobility of the heavy metals involved. In our study, we sought to replicate in a controlled manner this commonly used remediation strategy and measure Pb, Zn, Cu and As concentrations in all soil horizons-both prior to and 1 year after disruption by trenching. BCR analyses (sequential leaching) indicate that Pb is affected to the greatest degree and is most highly mobile; however, Zn and As remain insoluble, thus partially ameliorating the detrimental effect. Differences in vegetation cover (i.e. spruce vs. beech forest) have little influence on overall element mobility patterns. The Krušné hory (Ore Mts., Czech Republic) study area is one of the more heavily contaminated areas in Central Europe, and thus the results reported here are applicable to areas affected by brown-coal-burning power plants.

  12. ZnO-PbO-B2O3 glasses as gamma-ray shielding materials

    DEFF Research Database (Denmark)

    Singh, H.; Singh, K.; Gerward, Leif

    2003-01-01

    Values of the gamma-ray mass-attenuation coefficient, the photon mean free path (MFP), the effective atomic number and the effective electron density have been determined experimentally for xZnO.2xPbO.(1-3x)B2O3 (x = 0.1-0.26) glasses at photon energies 511, 662, 1173 and 1332 keV and compared wi...... with theoretical data. The specific volume of the glasses has been derived from density measurements and studied as a function of composition. It is pointed out that these glasses have potential applications in radiation shielding.......Values of the gamma-ray mass-attenuation coefficient, the photon mean free path (MFP), the effective atomic number and the effective electron density have been determined experimentally for xZnO.2xPbO.(1-3x)B2O3 (x = 0.1-0.26) glasses at photon energies 511, 662, 1173 and 1332 keV and compared...

  13. Lead (Pb) and Zinc (Zn) Concentrations in Marine Gastropod Strombus Canarium in Johor Coastal Areas

    International Nuclear Information System (INIS)

    Shaikhah Sabri; Mohd Ismid Mohd Said; Shamila Azman

    2014-01-01

    Strombus canarium is a popular food source with high commercial value in southern part of Peninsular Malaysia. As a deposit feeder, Strombus canarium can accumulate pollutants especially heavy metals in their system. Study on this species was conducted at Teluk Sengat and Mersing, Johor where samples of seawater and Strombus canarium were collected during spring low tides around 0 to 0.2 meters. Lead (Pb) and zinc (Zn) concentrations were investigated to determine pollution status in the area. Samples from Teluk Sengat showed that Zn has higher concentration in both water and S. canarium with 0.055 mg/ L and 20.257 mg/ kg wet weight respectively. However the concentrations were within permissible limit of Malaysia Marine Water Quality Criteria and Standard (MMWQS). In contrast, Pb concentration at Teluk Sengat exceeded the MMWQS and its concentration in soft tissues of S. canarium also exceeded the permissible limit recommended by Food and Agriculture Organisation (0.5 mg/ kg wet weight) and World Health Organisation (0.2 mg/ kg wet weight). (author)

  14. Effects of crucible wetting during solidification of immiscible Pb-Zn

    Science.gov (United States)

    Degroh, Henry C., III; Probst, Hubert B.

    1988-01-01

    Many industrial uses for liquid phase miscibility gap alloys are proposed. However, the commercial production of these alloys into useful ingots with a reasonable amount of homogeneity is arduous because of their immiscibility in the liquid state. In the low-g environment of space gravitational settling forces are abated, thus solidification of an immiscible alloys with a uniform distribution of phases becomes feasible. Elimination of gravitational settling and coalescence processes in low-g also makes possible the study of other separation and coarsening mechanisms. Even with gravitational separation forces reduced, many low-g experiments have resulted in severely segregated structures. The segregation in many cases was due to preferential wetting of the crucible by one of the immiscible liquids. The objective was to analyze the wetting behavior of Pb-Zn alloys on various crucible materials in an effort to identify a crucible in which the fluid flow induced by preferential wetting is minimized. It is proposed that by choosing the crucible for a particular alloy so that the difference in surface energy between the solid and two liqud phases is minimized, the effects of preferential wetting can be diminished and possibly avoided. Qualitative experiments were conducted and have shown the competitive wetting behavior of the immiscible Pb-Zn system and 13 different crucible materials.

  15. 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.

  16. 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.

  17. Accumulative response of Scots pine (Pinus sylvestris L.) and silver birch (Betula pendula Roth) to heavy metals enhanced by Pb-Zn ore mining and processing plants: Explicitly spatial considerations of ordinary kriging based on a GIS approach.

    Science.gov (United States)

    Pająk, Marek; Halecki, Wiktor; Gąsiorek, Michał

    2017-02-01

    Plants have an accumulative response to heavy metals present in soils or deposited from airborne sources of emissions. Therefore, their tissues are very often used in studies of heavy metal contamination originating from different sources as a bioindicator of environmental pollution. This research was undertaken to examine accumulation capacities of Pb, Zn, Cd, Cu and Cr in washed and unwashed needles of Scots pine (Pinus sylvestris L.) and leaves of silver birch (Betula pendula Roth) growing in a contaminated area. We collected needles of Scots pine and leaves of silver birch in an area around a sedimentation pond and metallurgic plant processing Pb and Zn ores near Olkusz, Poland. Concentrations of heavy metals, which have been linked with exposure to emissions, were determined from foliar samples collected at 33 sites. These sites were established at various distances (0.5-3.6 km) from the pond and metallurgic plant so as to identify the predominant accumulative response of plants. Spatial gradients for Pb and Zn were calculated using an ordinary kriging interpolation algorithm. A spatial pattern was identified by a GIS method to visualize maps over the Pb-Zn ore mining area. The accumulation of Zn (R 2  = 0.74, p < 0.05) and Pb (R 2  = 0.85, p < 0.01) in plant tissues correlated with soil concentrations. This tendency was not found in the case of Cu, Cd and Cr. Copyright © 2016 Elsevier Ltd. All rights reserved.

  18. HRTEM Analysis of Crystallographic Defects in CdZnTe Single Crystal

    Science.gov (United States)

    Yasar, Bengisu; Ergunt, Yasin; Kabukcuoglu, Merve Pinar; Parlak, Mehmet; Turan, Rasit; Kalay, Yunus Eren

    2018-01-01

    In recent years, CdZnTe has attracted much attention due to its superior electrical and structural properties for room-temperature operable gamma and x-ray detectors. However, CdZnTe (CZT) material has often suffered from crystallographic defects encountered during the growth and post-growth processes. The identification and structural characterization of these defects is crucial to synthesize defect-free CdZnTe single crystals. In this study, Cd0.95 Zn0.05 Te single crystals were grown using a three-zone vertical Bridgman system. The single crystallinity of the material was ensured by using x-ray diffraction measurements. High-resolution electron microscopy (HRTEM) was used to characterize the nano-scale defects on the CdZnTe matrix. The linear defects oriented along the ⟨211⟩ direction were examined by transmission electron microscopy (TEM) and the corresponding HRTEM image simulations were performed by using a quantitative scanning TEM simulation package.

  19. Pb isotopes as tracers of mining-related Pb in lichens, seaweed and mussels near a former Pb-Zn mine in West Greenland

    DEFF Research Database (Denmark)

    Søndergaard, Jens; Asmund, Gert; Johansen, Poul

    2010-01-01

    –2008. Stable Pb isotope ratios and total Pb concentrations were determined in lichens, seaweed and mussels as well as in marine sediments. The results show that natural background Pb (207Pb/206Pb: 0.704–0.767) and Pb originating from the mine ore (207Pb/206Pb: 0.955) have distinct isotopic fingerprints. Total...... Pb in lichens, seaweed, and mussels was measured at values up to 633, 19 and 1536 mg kg-1 dry weight, respectively, and is shown to be a mixture of natural Pb and ore-Pb. This enables quantification of mining-related Pb and shows that application of Pb isotope data is a valuable tool for monitoring...... mining pollution. Lead isotopes can be used to monitor uptake of mining-related lead in lichens, seaweed and mussels....

  20. Effect of NH4F/H2O2 Passivation on CdZnTe Detector

    International Nuclear Information System (INIS)

    Park, Se-Hwan; Ha, Jang-Ho; Cho, Yoon-Ho; Kim, Han-Soo; Kim, Yong-Kyun

    2006-01-01

    CdZnTe is the most promising material for X-ray and γ-ray detector. Many researchers have studied the fabrication process of CdZnTe detector. Generally, the CdZnTe crystal was grinded, mechanically polished, and chemically etched. After that, the metal electrodes were deposited on the crystal. Bromine/Methanol etchant is widely used for the chemical etching of the CdZnTe surface. The chemical etching is very important process to fabricate the CdZnTe radiation detector. The mechanical polishing would make the scratch on the CdZnTe surface, and remain the dangling bonds on the surface. The chemical etching could remove the mechanical scratch on the surface. However, the CdZnTe surface would remain non-stoichiometric after the chemical etching with Bromine/Methanol etchant, because the bromine reacts with cadmium more easily. The passivation is very important process to remove the non-stoichimetry of the CdZnTe surface. Also, the passivation could make the CdZnTe detector electrically inert to its environment

  1. 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. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. Comparison Of Cd And Zn Accumulation In Tissues Of Different Vascular Plants: A Radiometric Study

    Directory of Open Access Journals (Sweden)

    Dürešová Zuzana

    2015-12-01

    Full Text Available The aim of the present work was to compare the accumulation and translocation of Cd and Zn in plants of tobacco (Nicotiana tabacum L., celery (Apium graveolens L., maize (Zea mays L., giant reed (Arundo donax L., and alpine pennycress (Noccaea caerulescens L. under conditions of short-term hydroponic experiments using nutrient solutions spiked with radionuclides 109Cd or 65Zn, and direct gamma-spectrometry. It was found that the time-course of metals accumulation in studied plants was not different in terms of target metal, but it was significantly different on the level of plant species. The highest values of Cd accumulation showed plants of giant reed, whereby the accumulation decreased in the order: giant reed > tobacco > alpine pennycress >> maize and celery. On the basis of concentration ratios (CR [Me]shoot / [Me]root calculation for both metals, it was found that Cd and Zn were in prevailing part accumulated in the root tissues and only partially accumulated in the shoots, where the amount of accumulated Cd and Zn increased from the oldest developed leaves to the youngest developed leaves. The CR values corresponding to these facts were calculated in the range 0.06 – 0.27 for Cd and for Zn 0.06 – 0.48. In terms of plant species, the CR values obtained for Cd decreased in the order: maize > celery > tobacco and giant reed > alpine pennycress. The similarity between studied objects – individual plant species on the basis of the obtained variables defining Cd or Zn accumulation at different conditions of the experiments as well as the relationships between obtained variables and conditions of the experiments were subjected to multivariate analysis method – cluster analysis (CA. According to the findings and this analysis, it can be expected that plants of tobacco and giant reed will dispose with similar characteristics as plants of alpine pennycress, which are classified as Zn/Cd hyperaccumulators, in terms of Cd or Zn accumulation

  3. Speciation of binary complexes of Pb(II) and Cd(II) with L ...

    African Journals Online (AJOL)

    Chemical speciation of L-Asparagine complexes of Pb(II) and Cd(II) in presence of (0-50% v/v) dimethyl sulfoxide(DMSO)-water mixtures has been studied potentiometrically at 303.0 K and at an ionic strength of 0.16 mol L-1. The models containing different number of species were refined by using the computer program ...

  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.

  5. Competitive adsorption of Pb2+ and Cd2+ on magnetic modified sugarcane bagasse prepared by two simple steps

    Science.gov (United States)

    Yu, Jun-Xia; Wang, Li-Yan; Chi, Ru-An; Zhang, Yue-Fei; Xu, Zhi-Gao; Guo, Jia

    2013-03-01

    Magnetic modified sugarcane bagasse with high adsorption capacity and rapid adsorption rate was prepared by two simple steps. Experimental results showed that the adsorption capacities of the magnetic sorbent for Pb2+ and Cd2+ were 1.2 and 1.1 mmol g-1, respectively. Pseudo-second-order and pseudo-first-order kinetic model both could predict the adsorption and desorption kinetic process occurred on the modified sorbent. EDX analysis showed that Pb2+ and Cd2+ were adsorbed on the sorbent mainly through ion exchange. Competitive adsorption results showed that the presence of Pb2+ exerted a great inhibitory effect on Cd2+ adsorption, and the inhibitory effect increased with the increase of the initial concentration ratio of Pb2+ and Cd2+ (C0Pb: C0Cd). Pb2+ could be selectively adsorbed by the magnetic sorbent when the values of C0Pb: C0Cd was higher than or equal to 4:1. It was also found that Langmuir competitive model was suitable to predict the sorption isotherm in the binary system. The as prepared magnetic sorbent had a potential in heavy metal wastewater treatment.

  6. CdSe/ZnS core-shell QDs: Synthesis and investigating optical properties

    Science.gov (United States)

    Molaei, M.; Sarhani, F.; Bardsiri, F. Salari; Karmipour, M.

    2016-03-01

    In this work, CdSe quantum dots (QDs) were synthesized using a microwave activated reaction between NaHSe and CdSO4 in the presence of thioglycolic acid (TGA) as capping molecule and then using a one-pot method, ZnS shell was grown subsequently around CdSe cores by a room temperature reaction based on the photo-sensitivity of Na2S2O3 dissociation. Synthesized QDs were characterized by means of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), UV-visible (UV-Vis) and photoluminescence (PL) spectroscopy. All these analyses confirmed the formation of CdSe QDs and successful growth of ZnS shell around CdSe cores.

  7. Labeling efficiency and toxicity evaluation of CdSe/ZnS quantum dots on Escherichia coli

    Science.gov (United States)

    Zhao, Jin-Yun; Jia, Li-Min; Song, Wu-Qi; Zhang, Wen-Li; Fu, Ying-Mei; Zhang, Ying; Cao, Wen-Wu; Sun, Ye; Zheng, Jin-Hua; Zhang, Feng-Min

    2014-06-01

    In comparison with conventional organic dyes, quantum dots (QDs) have unique optical and electronic properties, which provide QDs with a wide scope of prospective application in biology and biomedicine. However, the toxicity of QDs and the fluorescence intensity of labeled bacteria must precede their application in bacterial imaging and tracing in vivo. Here, we show that treatment with CaCl2 significantly improved bacterial labeling efficiency of CdSe/ZnS QDs with the CdSe core size of 3.1 nm (relative fluorescence unit (RFU) value and ratio of fluorescent E. coli) with rising CdSe/ZnS QDs concentration in a concentration-dependent manner. At 12.5 nmol/L CdSe/ZnS QDs concentration, labeled Escherichia coli ( E. coli) DH5 α appeared as short rod-shaped and luminescent with normal size, and the survival rate and ultrastructure did not change in comparison to the control. But the ratio of fluorescent bacteria and RFU were very low. However, the survival rate of transformed E. coli was significantly inhibited by high CdSe/ZnS QDs concentrations (≥25 nmol/L). Moreover, internalization of CdSe/ZnS QDs resulted in ultrastructure damage of transformed E. coli in a concentration-dependent manner (≥25 nmol/L). Therefore, CdSe/ZnS QDs may not suitable for tracing of bacteria in vivo. Moreover, our study also revealed that colony-forming capability assay and transmission electron microscopy could be used to comprehensively evaluate the toxicity of QDs on labeled bacteria. Our findings do provide a new direction toward the improvement and modification of QDs for use in imaging and tracing studies in vivo.

  8. Geochemical and spectroscopic investigations of Cd and Pb sorption mechanisms on contrasting biochars: engineering implications.

    Science.gov (United States)

    Trakal, Lukáš; Bingöl, Deniz; Pohořelý, Michael; Hruška, Miroslav; Komárek, Michael

    2014-11-01

    Biochars prepared from nut shells, plum stones, wheat straws, grape stalks and grape husks were tested as potential sorbents for Cd and Pb. Mechanisms responsible for metal retention were investigated and optimal sorption conditions were evaluated using the RSM approach. Results indicated that all tested biochars can effectively remove Cd and Pb from aqueous solution (efficiency varied between 43.8% and 100%). The removal rate of both metals is the least affected by the biochar morphology and specific surface but this removal efficiency is strongly pH-dependent. Results of variable metal removal combined with different optimized conditions explain the different metal sorption mechanisms, where the predominant mechanism is ion exchange. In addition, this mechanism showed very strong binding of sorbed metals as confirmed by the post-desorption of the fully metal-loaded biochars. Finally, these biochars could thus also be applicable for metal contaminated soils to reduce mobility and bioavailability of Cd and Pb. Copyright © 2014 Elsevier Ltd. All rights reserved.

  9. Pb and Cd in medicinal plants (Case study: Shirazi thyme, sweet violet, pennyroyal and jujube

    Directory of Open Access Journals (Sweden)

    Masoomeh Karimi

    2016-12-01

    Full Text Available Introduction: Medicinal plants are a major source of drugs for the majority of people in the world. Unfortunately, little data is available on the safety of medicinal plants, especially in terms of heavy metal contamination. Therefore, this study was conducted to evaluate the potential risk of Pb and Cd in Shirazi thyme, sweet violet, pennyroyal and jujube marketed in Hamedan City in 2015. Methods: After preparation of 3 samples of each medicinal plant and acid digestion of the samples according to standard methods, the concentration of elements in samples were determined using atomic absorption spectrophotometer (AAS in 3 replicates. Also, all statistical analyses were performed in the SPSS software. Results: The results showed that the maximum mean concentrations of Pb and Cd in specimens were 1420±30 and 40±30 µg/kg for thyme and viola, respectively. The results of health index for all samples were smaller than one for all samples. Also the mean concentrations of Pb and Cd in all samples were lower than WHO permissible limits. Conclusion: Controlled consumption of medicinal plants has no adverse effects on the consumers’ health. However, given the increased use of pesticides, chemical fertilizers, sewage sludge and wastewater by farmers, it is recommended that medicinal plants be regularly monitored for chemical pollutants especially heavy metals.

  10. 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.

  11. KANDUNGAN LOGAM BERAT (Hg, Cd, dan Pb DALAM AIR TANAH PADA PERUMAHAN TIPE KECIL DI JABOTABEK

    Directory of Open Access Journals (Sweden)

    Athena Athena

    2012-09-01

    Full Text Available A survey of heavy metals (Hg, Cd, Pb in drinking water at small and very small houses was conducted in Jakarta, Bogor, Tangerang and Bekasi (Jabotabek, in 1992. The purpose of this study was to get information about water quality and environmental condition of water sources at low cost housing and very low cost housing in Jabotabek. Forty to sixty water samples were taken from each location and analyzed by Atomic Absorption Spectrophotometer. The mercury concentration was analyzed using Cold Vapor Technique, whereas Cd and Pb were analized using The Air-acetylene method. Water samples were collected in dry season and rainy season. Interview of the owners of the house and of environmental observation of the water sources were done to get information about the condition of drinking water sources. The highest concentration of mercury detected in Jakarta was in the rainy season (2.50 mg/l. Cadmium and Lead were detected in Bogor, (Cd: 0.26 mg/l in the rainy season and Pb : 0.16 mg/l in dry season. However 41.5% water samples from Jakarta were exceeding the mercury concentration standard, 25.4% water samples from Bogor were exceeding cadmium concentration standard, and 41.1% water samples from Bogor were exceeding lead concentration standard Heavy metals concentration in drinking water at Bekasi and Tangerang were relatively lower than Bogor and Jakarta. The environmental condition of shallow wells in Bekasi and Tangerang were also better than Bogor and Jakarta.

  12. Cu-Zn-Pb multi isotopic characterization of a small watershed (Loire river basin, France)

    Science.gov (United States)

    Desaulty, A. M.; Millot, R.; Perret, S.; Bourrain, X.

    2015-12-01

    Combating metal pollution in surface water is a major environmental, public health and economic issue. Knowledge of the behavior of metals, such as copper (Cu), zinc (Zn) and lead (Pb) in sediments and dissolved load, is a key factor to improve the management of rivers. Recent advances in mass spectrometry related to the development of MC-ICPMS allow to analyze the isotopic composition of these elements, and previous studies show the effectiveness of isotopic analyses to determine the anthropogenic sources of pollution in environment. The goal of this study is to use the Cu-Zn-Pb multi-isotopic signature to track the pollutions in surface water, and to understand the complex processes causing the metals mobilization and transport in environment. More particularly we investigate the mechanisms of distribution between the dissolved load and particulate load, known to play an important role in the transport of metals through river systems. As case study, we chose a small watershed, poorly urbanized in the Loire river basin. Its spring is in a pristine area, while it is only impacted some kilometers further by the releases rich in metals coming from a hospital water treatment plant. First a sampling of these liquid effluents as well as dissolved load and sediment from upstream to downstream was realized and their concentrations and isotopic data were determined. Then to simulate a lot of potential natural and anthropogenic modifications of environmental conditions, we made sequential extraction protocol using various reagents on the sediments. Isotopic analyzes were performed also on the various extracting solutions. Isotopic ratios were measured using a Neptune MC-ICPMS at the BRGM, after a protocol of purification for Zn and Cu. The results showed that, these isotopic systematics reveal important informations about the mechanists of mobilization and transport of metals through river systems. However experiments performed under laboratory conditions will be necessary

  13. Wide emission-tunable CdTeSe/ZnSe/ZnS core–shell quantum dots and their conjugation with E. coli O-157

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Haifeng [State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100 (China); Zhou, Guangjun, E-mail: gjzhou@sdu.edu.cn [State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100 (China); Zhou, Juan [Center for Disease Control and Prevention of Jinan Military Command, Jinan 250014 (China); Xu, Dong; Zhang, Xingshuang; Kong, Peng; Yang, Zhongsen [State Key Laboratory of Crystal Materials, Shandong University, Jinan 250100 (China)

    2015-05-15

    Highlights: • QDs with variety morphology were obtained via an injection controlled process. • 3-D PL spectra of core–shell QDs show different excitation wavelength dependence. • The PL intensity of QDs with ZnSe transition layer increases dramatically. • Core–shell QDs were processed into aqueous phase and conjugated with E. coli O-157. - Abstract: Wide emission-tunable and different morphological alloyed CdTeSe quantum dots (QDs), CdTeSe/ZnS and CdTeSe/ZnSe/ZnS core–shell QDs were successfully synthesized via an injection controlled process. The effect of injection procedure and reaction temperature were systematically discussed and the growth mechanism was proposed. Most efficient PL wavelength was correlated with reaction time and temperature. The 3-D PL spectra of spherical bare CdTeSe and core–shell QDs with different passivation showed different excitation wavelength dependency. The PL intensity of CdTeSe/ZnSe/ZnS core–shell QDs increased greatly in comparison with that of CdTeSe and CdTeSe/ZnSe QDs. ZnSe transition layer played an important role in improving the PL intensity by providing a smoothened interface and gradient band offsets. The core–shell QDs were transferred into aqueous phase and successfully conjugated with Escherichia coli O-157. The proposed phase-transfer and bio-labeling strategy may be applicable to various QDs with different compositions.

  14. Selective UV radiation detection on the basis of low-dimensional ZnCdS/ZnMgS/GaP and ZnCdS/ZnS/GaP heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Averin, S. V., E-mail: sva278@ire216.msk.su; Kuznetzov, P. I.; Zhitov, V. A.; Zakharov, L. Yu.; Kotov, V. M.; Alkeev, N. V. [Russian Academy of Sciences, Fryazino Branch, Kotel’nikov Institute of Radio Engineering and Electronics (Russian Federation); Gladisheva, N. B. [Pulsar State Plant (Russian Federation)

    2015-11-15

    The detecting properties of periodic heterostructures with ZnCdS quantum wells separated by ZnMgS or ZnS barrier layers are studied. Heterostructures are grown on semi-insulating GaP substrates by metal organic vapor-phase epitaxy (MOVPE). On their basis, metal–semiconductor–metal (MSM) diodes with interdigital Schottky contacts 3 μm, distances between them of 3 μm, and a total detector area of 100 × 100 μm are fabricated. The detectors have low dark currents (10{sup –12} A); at low bias voltages, they provide a narrow- band response (full-width at half-maximum of FWHM = 18 nm at a wavelength of 350 nm) which is controlled by the ZnCdS quantum-well composition. As bias is increased to 70 V, the maximum detector sensitivity shifts by a wavelength of 450 nm, which is caused by penetration of the external-bias electric field into the semi-insulating GaP substrate. In this case, the narrow-band response of the detector at a wavelength of 350 nm is retained, i.e., the two-color detection of light is provided.

  15. Growth and optical properties of CdTe quantum dots in ZnTe nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Wojnar, Piotr; Janik, Elzbieta; Baczewski, Lech T.; Kret, Slawomir; Karczewski, G.; Wojtowicz, Tomasz [Institute of Physics, Polish Academy of Sciences, Al Lotnikow 32/46, 02-668 Warsaw (Poland); Goryca, Mateusz; Kazimierczuk, Tomasz; Kossacki, Piotr [Institute of Experimental Physics, Faculty of Physics, University of Warsaw, ul Hoza 69, 00-681 Warsaw (Poland)

    2011-09-12

    We report on the formation of optically active CdTe quantum dots in ZnTe nanowires. The CdTe/ZnTe nanostructures have been grown by a gold nanocatalyst assisted molecular beam epitaxy in a vapor-liquid solid growth process. The presence of CdTe insertions in ZnTe nanowire results in the appearance of a strong photoluminescence band in the 2.0 eV-2.25 eV energy range. Spatially resolved photoluminescence measurements reveal that this broad emission consists of several sharp lines with the spectral width of about 2 meV. The large degree of linear polarization of these individual emission lines confirms their nanowire origin, whereas the zero-dimensional confinement is proved by photon correlation spectroscopy.

  16. Adaptation of soil microbial community structure and function to chronic metal contamination at an abandoned Pb-Zn mine.

    Science.gov (United States)

    Epelde, Lur; Lanzén, Anders; Blanco, Fernando; Urich, Tim; Garbisu, Carlos

    2015-01-01

    Toxicity of metals released from mine tailings may cause severe damage to ecosystems. A diversity of microorganisms, however, have successfully adapted to such sites. In this study, our objective was to advance the understanding of the indigenous microbial communities of mining-impacted soils. To this end, a metatranscriptomic approach was used to study a heavily metal-contaminated site along a metal concentration gradient (up to 3220 000 and 97 000 mg kg(-1) of Cd, Pb and Zn, respectively) resulting from previous mining. Metal concentration, soil pH and amount of clay were the most important factors determining the structure of soil microbial communities. Interestingly, evenness of the microbial communities, but not its richness, increased with contamination level. Taxa with high metabolic plasticity like Ktedonobacteria and Chloroflexi were found with higher relative abundance in more contaminated samples. However, several taxa belonging to the phyla Actinobacteria and Acidobacteria followed opposite trends in relation to metal pollution. Besides, functional transcripts related to transposition or transfer of genetic material and membrane transport, potentially involved in metal resistance mechanisms, had a higher expression in more contaminated samples. Our results provide an insight into microbial communities in long-term metal-contaminated environments and how they contrast to nearby sites with lower contamination. © FEMS 2014. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  17. Streptomyces pactum assisted phytoremediation in Zn/Pb smelter contaminated soil of Feng County and its impact on enzymatic activities

    Science.gov (United States)

    Ali, Amjad; Guo, Di; Mahar, Amanullah; Ma, Fang; Li, Ronghua; Shen, Feng; Wang, Ping; Zhang, Zengqiang

    2017-04-01

    Anthropogenic activities, such as industrial expansion, smelting, mining and agricultural practices, have intensified the discharge of potentially toxic trace elements (PTEs) into the environment, threatening human health and other organisms. To assist phytoremediation by sorghum in soil contaminated by smelters/mines in Feng County (FC), a pot experiment was performed to examine the phytoremediation potential of Streptomyces pactum (Act12) + biochar. The results showed that root uptake of Zn and Cd was reduced by 45 and 22%, respectively, while the uptake of Pb and Cu increased by 17 and 47%, respectively. The shoot and root dry weight and chlorophyll content improved after Act12 inoculation. β-glucosidase, alkaline phosphatase and urease activities in soil improved and antioxidant activities (POD, PAL, PPO) decreased after application of Act12 + biochar due to a reduction in stress from PTEs. BCF, TF and MEA confirmed the role of Act12 in the amelioration and translocation of PTEs. PCA analysis showed a correlation between different factors that affect the translocation of PTEs. Overall, Act12 promoted the phytoremediation of PTEs. Field experiments on Act12 + biochar may provide new insights into the rehabilitation and restoration of soils contaminated by mines.

  18. Regional Variability of