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Sample records for pb cd zn

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

    PubMed

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

    2010-08-01

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

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

    PubMed

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

    2010-08-01

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

  3. Accumulation of Cd, Pb and Zn by 19 wetland plant species in constructed wetland.

    PubMed

    Liu, Jianguo; Dong, Yuan; Xu, Hai; Wang, Deke; Xu, Jiakuan

    2007-08-25

    Uptake and distribution of Cd, Pb and Zn by 19 wetland plant species were investigated with experiments in small-scale plot constructed wetlands, into which artificial wastewater dosed with Cd, Pb and Zn at concentrations of 0.5, 2.0 and 5.0mgl(-1) was irrigated. The results showed that the removal efficiency of Cd, Pb and Zn from the wastewater were more than 90%. Generally, there were tens differences among the 19 plant species in the concentrations and quantity accumulations of the heavy metals in aboveground part, underground part and whole plants. The distribution ratios into aboveground parts for the metals absorbed by plants varied also largely from about 30% to about 90%. All the plants accumulated, in one harvest, 19.85% of Cd, 22.55% of Pb and 23.75% of Zn that were added into the wastewater. Four plant species, e.g. Alternanthera philoxeroides, Zizania latifolia, Echinochloa crus-galli and Polygonum hydropiper, accumulated high amounts of Cd, Pb and Zn. Monochoria vaginalis was capable for accumulating Cd and Pb, Isachne globosa for Cd and Zn, and Digitaria sanguinalis and Fimbristylis miliacea for Zn. The results indicated that the plants, in constructed wetland for the treatment of wastewater polluted by heavy metals, can play important roles for removal of heavy metals through phytoextraction. Selection of plant species for use in constructed wetland will influence considerably removal efficiency and the function duration of the wetland. PMID:17353090

  4. Accumulation of Cd, Pb and Zn by 19 wetland plant species in constructed wetland.

    PubMed

    Liu, Jianguo; Dong, Yuan; Xu, Hai; Wang, Deke; Xu, Jiakuan

    2007-08-25

    Uptake and distribution of Cd, Pb and Zn by 19 wetland plant species were investigated with experiments in small-scale plot constructed wetlands, into which artificial wastewater dosed with Cd, Pb and Zn at concentrations of 0.5, 2.0 and 5.0mgl(-1) was irrigated. The results showed that the removal efficiency of Cd, Pb and Zn from the wastewater were more than 90%. Generally, there were tens differences among the 19 plant species in the concentrations and quantity accumulations of the heavy metals in aboveground part, underground part and whole plants. The distribution ratios into aboveground parts for the metals absorbed by plants varied also largely from about 30% to about 90%. All the plants accumulated, in one harvest, 19.85% of Cd, 22.55% of Pb and 23.75% of Zn that were added into the wastewater. Four plant species, e.g. Alternanthera philoxeroides, Zizania latifolia, Echinochloa crus-galli and Polygonum hydropiper, accumulated high amounts of Cd, Pb and Zn. Monochoria vaginalis was capable for accumulating Cd and Pb, Isachne globosa for Cd and Zn, and Digitaria sanguinalis and Fimbristylis miliacea for Zn. The results indicated that the plants, in constructed wetland for the treatment of wastewater polluted by heavy metals, can play important roles for removal of heavy metals through phytoextraction. Selection of plant species for use in constructed wetland will influence considerably removal efficiency and the function duration of the wetland.

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

    PubMed

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

    2015-08-15

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

  6. Removal, redistribution, and potential risks of soil Cd, Pb, and Zn after washing with various extractants.

    PubMed

    Chen, Chunle; Chen, Yanhui; Xie, Tuanhui; Wang, Ming Kuang; Wang, Guo

    2015-11-01

    The effectiveness of four different washing extractants--HCl, FeCl3, citric acid, and EDTA--in removing Cd, Pb, and Zn from polluted soil was studied. The removal of these metals, their redistribution between fractions, and the potential risks posed by them, in soils washed with the tested extractants, were examined. Although all the rounds of washing removed Cd, Pb, and Zn from soil, the first round removed more metals than subsequent rounds. Each of the four extractants had different effects on the removal of the metals. At the end of the first round of washing, HCl, EDTA, and FeCl3 were the most effective in removing Zn, Pb, and Cd, respectively. Both the single round and five successive rounds of washing with various extractants resulted in significant increases in Pb in the exchangeable/acid extractable fraction. Washing with HCl, EDTA, and FeCl3 significantly reduced potential risks (calculated as the Potential Risk Index, PRI) posed by Cd in washed soil. The first round of washing, using all extractants, increased the risks posed by Pb and Zn. However, five successive rounds of washing with FeCl3 and EDTA reduced the risk posed by Pb, and washing with citric acid and FeCl3 increased the risks posed by Zn. EDTA and HCl were better for reducing Zn risks, and successive washing with EDTA and FeCl3 were more effective in reducing Pb risks than the other extractants. Finally, five successive rounds of washing, with all the extractants, effectively reduced the potential risks posed by Cd. Among the four reagents, EDTA was advised to be the alternative of the washing reagent by significantly reducing the PRI values of Cd, Pb, and Zn.

  7. Simultaneous Incorporation of Cr, Zn, Cd, and Pb in the Goethite Structure

    SciTech Connect

    Kaur, Navdeep; Gräfe, Markus; Singh, Balwant; Kennedy, Brendan

    2009-10-21

    In order to improve our understanding of how the goethite crystal structure is affected by the incorporation of metals (and by variations in the amount of the incorporation), and to review any possible synergistic and antagonistic effects of co-metals, the present investigation focused on the incorporation of multiple (di-, tri-, and tetra-) metals, i.e. Cr, Zn, Cd, and Pb, in the goethite crystallographic structure. A series of single- and multi-metal M-Cr/Zn/Cd/Pb-substituted goethites with M/(M+Fe) molar ratios = 0.10 were prepared. The general sequence of metal entry in single-metal substituted goethites was Zn = Cr > Cd > Pb and in multi-metal-substituted goethites was Zn > Cr {ge} Cd > Pb. Simultaneous incorporation of Cr, Zn, Cd, and Pb up to 10.5 mole % was achieved in goethite. Synchrotron X-ray diffraction and extended X-ray absorption fine structure (EXAFS) techniques were employed to assess the structural characteristics of the synthesis products. Rietveld refinement of XRD data showed small changes in unit-cell parameters and Fe/M-Fe/M distances due to M substitution(s). A typical goethite-like crystalline structure remained intact, however. The unit-cell parameters were mutually, linearly correlated, though Fe/M-Fe/M distances were not, indicating that complex changes occurred at the local scale. In single-metal substituted goethites, incorporation of Cr reduced the unit-cell volume by 0.13% while that of Zn, Cd, and Pb increased it by 1.09, 3.58, and 0.56%, respectively. The changes in multi-metal-substituted goethites appeared to be the complex combination of that of the individually incorporated metals. The X-ray absorption near edge structure study of Pb-substituted goethites showed that the majority of associated Pb was Pb{sup 2+}, while Pb{sup 4+} was preferred over Pb{sup 2+} in the bulk structure. Measurements by EXAFS at the Fe K-edge indicated that the Fe polyhedra contracted in the presence of Cd{sup 2+} and Pb{sup 2+}, providing room for

  8. Effects of Se and Zn supplementation on the antagonism against Pb and Cd in vegetables.

    PubMed

    He, P P; Lv, X Z; Wang, G Y

    2004-04-01

    The antagonistic effects of supplementation of Zn and Se to the soil on vegetables were studied in this work. In the pot experiment, Se (Se4+) and Zn (Zn2+) were applied, respectively, to the soil, in which the Chinese cabbage (Brassica rapa) and the lettuce (Lactuca sativa L.) were planted. As a result, Se and Zn were enriched evidently in the two vegetables. The contents of Pb and Cd in the two vegetables were decreased markedly while contents of some healthy mineral elements, like Mn and Mg, were increased to some extent when Se and Zn were applied. The antagonism of Se and Zn against Pb and Cd in plants was suggested. The farmland experiment on the lettuce was conducted to explore further the effect of supplementation of Zn and Se under the actual field conditions. Result came out to be that the enrichment of Zn and Se restrained the accumulation of Pb and Cd in the lettuce remarkably, as well as enhanced the absorption of some other nutritional elements, like Fe, Mn, Cu, Ca and Mg. Therefore, application of Se and Zn was proved to be an effective and feasible method to improve trace elements nutrition in the vegetables.

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

    PubMed

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

    2004-06-01

    A field survey of higher terrestrial plants growing on Lanping lead-zinc mine, China were conducted to identify species accumulating exceptionally large concentrations of Pb, Cd, Cu and Zn of 20 samples of 17 plant species. Concentrations of Pb and Zn in soil and in plant were higher than that of Cu and Cd. Significant difference was observed among the average concentrations of four heavy metals in plants (except Cd and Cu) and in soil (except Pb and Zn) (P<0.05). For the enrichment coefficient of the four heavy metals in plant, the order of average was Pb. Between four heavy metals, only significant difference was observed between the enrichment coefficient average of Cd and Cu (P<0.05). The enrichment coefficients were higher than 1 in Llex plyneura and Rhododendron annae in Paomaping for Pb, Salix cathayana, L. plyneura and R. annae in Paomaping for Cd, and R. annae in Paomaping for Zn, respectively. Concentrations and enrichment coefficient of Pb, Cd and Zn of Rhododendron were higher than that of Gramimeae. Enrichment coefficient of Pb, Cd and Zn were bush>tree>herbaceous, and herbaceous grew in soil with the highest concentrations of four heavy metals. In different areas, the concentrations of Pb, Cd, Cu and Zn in plants and soils and enrichment coefficient were different. Plants in Paomaping had more accumulating ability to Pb, Cd and Zn, and plants in Jinfeng River had more accumulating ability to Cu. Six plant species, i.e. S. cathayana, Lithocarpus dealbatus, L. plyneura, Fargesia dura, Arundinella yunnanensis and R. annae in Paomaping, had high accumulation capacity. R. annae in Paomaping had hyperaccumulating capacity to Pb, Cd and Zn, L. plyneura to Pb and Cd, and S. cathayana to Cd, respectively. PMID:15031017

  10. [Leaching behavior of Pb, Cd and Zn from soil stabilized by lime stabilized sludge].

    PubMed

    Li, Xiang; Song, Yun; Liu, Yong-Bing

    2014-05-01

    Stabilization of Pb, Cd and Zn spiked soil by using lime-stabilized sewage sludge( LSS) as amendment was investigated in this study, and the effectiveness was evaluated by using leaching tests ( TCLP, SPLP and de-ionized water) and modified BCR sequential extraction procedure. The results of TCLP indicated that the concentrations of heavy metals in TCLP leachate reduced significantly with the increase of the mass percentage of the LSS and the leaching reduction rates were as high as 99. 54% for Zn, 99. 60% for Pb, 99. 85% for Cd at 40% of LSS addition. When evaluated by SPLP and de-ionized water leaching method, the concentrations of Zn and Pb in leachate decreased obviously at 10% and 20% of LSS additions, but subsequently increased at 30% and 40% because of redissolution of Zn and Pb at strong base condition. After pH value of LLS-stabilized soil was adjusted by ferrous sulfate and phosphoric acid for recovering soil plantation function, the pH value of the soil decreased effectively, in the meantime promoting the stabilization effectiveness of Pb and Zn. The BCR test revealed that compared with the spiked soil exchangeable proportion of Zn, Pb, Cd in the soil and the soils adjusted by ferrous sulfate obviously declined, which implied the migration for Pb, Cd and Zn of contaminated soil could be confined. This study results show that municipal LSS can be reused in the stabilization of heavy metal contaminated soils and physical and chemical properties of LLS-stabilized soil are improved for plantation.

  11. Concentrations of Cd, Pb, Mn and Zn in feathers and diet in heron chicks in Korea.

    PubMed

    Kim, Jungsoo; Oh, Jong-Min

    2015-01-01

    The feathers and diet items of grey heron (Ardea cinerea) and black-crowned night-heron (Nycticorax nycticorax) chicks were collected at the Pyeongtaek colony, Korea in 2002 and 2008, and Cd, Pb, Mn and Zn concentrations were measured. Cd and Zn concentrations were higher in both species in 2008 than 2002 and were higher in grey herons than black-crowned night-herons in 2002. In 2008, Cd concentrations were higher in black-crowned night-herons than grey herons; Zn concentrations did not differ between species. Pb and Mn concentrations did not differ between species; however, there were yearly differences. Cd, Pb and Zn concentrations of feathers and diet were significantly correlated when species and years were combined. However, the predictive power of these relationships was limited because of species and yearly differences. All heron chicks had concentrations of Cd (<2 μg/g dw) and Pb (<4 μg/g dw) consistent with background concentrations for wild birds. Mn and Zn concentrations were within the range reported for other heron and egret species.

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

    PubMed

    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.

  13. Pb, Zn and Cd mobility, availability and fractionation in aged soil remediated by EDTA leaching.

    PubMed

    Udovic, Metka; Lestan, Domen

    2009-03-01

    Soil washing remediation techniques usually remove only the labile heavy metal (HM) species from the soil, leaving the residual ones in less available/mobile forms, thus disturbing the chemical equilibrium among different species of HM in the soil. Re-establishing such equilibrium and shifting HM back to more available/mobile chemical forms could occur after exposing the remediated soil to environmental abiotic (ageing) factors. Contaminated soil from a smelter site (Pb 4600 mg kg(-1), Zn 1800 mg kg(-1), Cd 30 mg kg(-1)) was leached with increasing EDTA concentrations (2.5, 5.0, 10.0, 20.0, 40.0 and 4-consecutive steps of 40.0 mmol EDTA kg(-1) of soil). A gradient of removed HM was reached: from 6% to 73% of initial Pb, from 3% to 23% of initial Zn and from 17% to 74% of initial Cd were removed. Repetitive temperature changes (105 degrees C and -20 degrees C) were used to mimic abiotic factors acting on residual HM after EDTA soil leaching in saturated soil at 10% and 90% of soil water holding capacity. Fractionation using sequential extractions, mobility, and phytoavailability of Pb, Zn and Cd and Pb oral bioavailability were determined for aged and non-aged soil. The ageing treatment consistently lowered HM phytoavailability in the original (non-leached) and all treated (chelant-leached) soils. However, Pb, Zn and Cd behaved differently from each other; Pb mobility increased, Cd mobility decreased, while Zn mobility did not change. The results indicate that abiotic (ageing) processes change the availability/mobility of residual HM in all leaching treatments and should thus be considered in final remediation effectivity evaluation.

  14. Enhanced phytoextraction of Cu, Pb, Zn and Cd with EDTA and EDDS.

    PubMed

    Luo, Chunling; Shen, Zhenguo; Li, Xiangdong

    2005-03-01

    Chemically enhanced phytoextraction has been proposed as an effective approach to removing heavy metals from contaminated soil through the use of high biomass plants. Using pot experiments, the effects of the application of EDTA, EDDS and citric acid on the uptake of Cu, Pb, Zn and Cd by corn (Zea mays L. cv. Nongda 108) and bean (Phaseolus vulgaris L. white bean) plants were studied. The results showed that EDDS was more effective than EDTA at increasing the concentration of Cu in corn and beans. The application of 5 mmol kg-1 soil EDDS to soil significantly increased concentrations of Cu in shoots, with maximum levels of 2060 and 5130 mg kg-1 DW in corn and beans, respectively, which were 45- and 135-fold higher than that in the corresponding control plants to which chelate had not been applied. Concentrations of Zn in shoots were also higher in the plants treated with EDDS than in those treated with EDTA. For Pb and Cd, EDDS was less effective than EDTA. The maximum Cu phytoextraction was found with the EDDS treatment. The application of EDTA and EDDS also significantly increased the shoot-to-root ratios of the concentrations of Cu, Pb, Zn and Cd in both plant species. The results of metal extraction with chelates showed that EDDS was more efficient at solubilizing Cu and Zn than EDTA, and that EDTA was better at solubilizing Pb and Cd than EDDS.

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

    SciTech Connect

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

    2009-01-01

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

  16. Tracing Cd, Zn and Pb pollution sources in bivalves using isotopes

    NASA Astrophysics Data System (ADS)

    Shiel, A. E.; Weis, D. A.; Orians, K. J.

    2010-12-01

    In a multi-tracer study, Cd, Zn and Pb isotopes (MC-ICP-MS) and elemental concentrations (HR-ICP-MS) are evaluated as tools to distinguish between natural and anthropogenic sources of these metals in bivalves from western Canada (British Columbia), the eastern USA, Hawaii and France. High Cd concentrations found in BC oysters have elicited economic and health concerns. The source of these high Cd levels is unknown but thought to be largely natural. High Cd levels in BC oysters are largely attributed to the natural upwelling of Cd-rich intermediate waters in the North Pacific as the δ114/110Cd (-0.69 to -0.09‰) and δ66/64Zn (0.28 to 0.36‰) values of BC oysters fall within the range reported for North Pacific seawater. Different contributions from anthropogenic sources account for the variability of Cd isotopic compositions of BC oysters; the lightest of these oysters are from the BC mainland. These oysters also have Pb isotopic compositions that reflect primarily anthropogenic sources (e.g., leaded and unleaded automotive gasoline and smelting of Pb ores, potentially historical). On the contrary, USA East Coast bivalves exhibit relatively light Cd isotopic compositions (δ114/110Cd = -1.20 to -0.54‰; lighter than reported for North Atlantic seawater) due to the high prevalence of industry on this coast. The Pb isotopic compositions of these bivalves indicate contributions from the combustion of coal. The large variability of environmental health among coastal areas in France is reflected in the broad range of Cd isotopic compositions exhibited by French bivalves (δ114/110Cd = -1.08 to -0.20‰). Oysters and mussels from the Marennes-Oléron basin and Gironde estuary have the lightest Cd isotopic compositions of the French oysters consistent with significant historical Cd emissions from the now-closed proximal Zn smelter. In these bivalves, significant declines in the Cd levels between 1984/7 and 2004/5 are not accompanied by a significant shift in the Cd

  17. Competitive sorption of Cd, Cu, Mn, Ni, Pb and Zn in polluted and unpolluted calcareous soils.

    PubMed

    Jalali, Mohsen; Moradi, Fahimeh

    2013-11-01

    The objectives of this study were to investigate competitive sorption behaviour of heavy metals (Cd, Cu, Mn, Ni, Pb and Zn) under different management practices and identify soil characteristics that can be correlated with the retention and mobility of heavy metals using 65 calcareous soil samples. The lowest sorption was found for Mn and Ni in competition with the other metals, indicating the high mobility of these two cations. The Freundlich equation adequately described heavy metals adsorption. On the basis of Freundlich distribution coefficient, the selectivity sequence of the metal adsorption was Cu > Pb > Cd > Zn > Ni > Mn. The mean value of the joint distribution coefficient (K dΣsp) was 182.1, 364.1, 414.7, 250.1, 277.7, 459.9 and 344.8 l kg(-1) for garden, garlic, pasture, potato, vegetables, wheat and polluted soils, respectively. The lowest observed K dΣsp in garden soil samples was due to the lower cation exchange capacity and lower carbonate content. The results of the geochemical modelling under low and high metal addition indicated that Cd, Ni, Mn and Zn were mainly retained via adsorption, while Pb and Cu were retained via adsorption and precipitation. Stepwise forward regression analysis showed that clay, organic matter and CaCO3 were the most important soil properties influencing competitive adsorption of Cd, Mn, Ni and Zn. The results in this study point to a relatively easy way to estimate distribution coefficient values. PMID:23677680

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

    PubMed

    Søndergaard, Jens

    2013-12-01

    Accumulation dynamics and cellular locations of lead (Pb), zinc (Zn) and cadmium (Cd) were studied in Flavocetraria nivalis lichens near the former Black Angel Pb-Zn Mine in West Greenland. Natural resident thalli were collected from four dust-contaminated sites near the mine. In addition, thalli were taken from an uncontaminated reference site and transplanted to the contaminated sites followed by a collection 1 year after. Total thalli metal contents were determined, and thalli were subjected to a sequential extraction procedure. After 1 year of transplantation, total Pb thalli contents were significantly elevated compared with initial concentrations at all sites (for Zn and Cd contents only at the two sites closest to the mine). However, transplanted thalli contained significantly less Pb (26 ± 12%), Zn (64 ± 13%) and Cd (34 ± 7 %) compared with resident thalli from these sites. Results from the sequential extraction procedure showed marked differences among Pb, Zn and Cd in the extracellular, intracellular and residual fraction. The lower total metal concentrations in transplanted compared with resident thalli at the contaminated sites were mostly due to a larger metal content bound in the residual fraction in resident thalli. In contrast, the metal content bound in the extracellular fraction were not significantly different in transplanted and resident thalli. The results indicate that extracellular-bound Pb, Zn and Cd in F. nivalis can be used as a proxy for recent (annual) atmospheric metal deposition whereas the large residual metal fraction in resident lichens indicate an accumulation of metal-containing particles in the thalli over time that includes several years of uptake.

  19. Determining provenance of marine metal pollution in French bivalves using Cd, Zn and Pb isotopes

    NASA Astrophysics Data System (ADS)

    Shiel, Alyssa E.; Weis, Dominique; Cossa, Daniel; Orians, Kristin J.

    2013-11-01

    Cadmium, Zn and Pb isotopic compositions (MC-ICP-MS) and elemental concentrations (HR-ICP-MS) have been used to distinguish between natural and anthropogenic sources of these metals in bivalves collected from the coastlines of France (English Channel, Atlantic and Mediterranean coasts). The Cd isotopic signatures (δ114Cd = -1.08‰ to -0.52‰) exhibited by bivalves from the coastlines of France, excluding those from NE France, are within the range of those exhibited by bivalves from the USA East coast (δ114Cd = -1.20‰ to -0.54‰). This indicates the high prevalence of industry, as well as the low natural contributions of Cd from North Atlantic waters in both regions. Thus, the significance of anthropogenic Cd sources is similar. These significant anthropogenic contributions are identified for bivalves with a large range in tissue Cd concentrations. Importantly, French bivalves from the Gironde estuary and Marennes-Oléron basin (regions of historic and modern importance for oyster farming, respectively) exhibited the highest Cd levels of the study. Their Cd isotopic signatures indicate historical smelting emissions remain the primary Cd source despite the cessation of local smelting activities in 1986 and subsequent remedial efforts. No significant variability is observed in the δ66Zn values of the French bivalves (∼0.53‰), with the exception of the much heavier compositions exhibited by oysters from the polluted Gironde estuary (1.19-1.27‰). Lead isotopes do not fractionate during processing like Cd and Zn. They can, therefore, be used to identify emissions from industrial processes and the consumption of unleaded gasoline and diesel fuel as metal sources to French bivalves. Cadmium and Zn isotopes are successfully used here as tracers of anthropogenic processing emissions and are combined with Pb isotope "fingerprinting" techniques to identify metal sources.

  20. EDTA and citric acid mediated phytoextraction of Zn, Cu, Pb and Cd through marigold (Tagetes erecta).

    PubMed

    Sinhal, V K; Srivastava, Alok; Singh, V P

    2010-05-01

    Phytoextraction is an emerging cost-effective solution for remediation of contaminated soils which involves the removal of toxins, especially heavy metals and metalloids, by the roots of the plants with subsequent transport to aerial plant organs. The aim of the present investigation is to study the effects of EDTA and citric acid on accumulation potential of marigold (Tagetes erecta) to Zn, Cu, Pb, and Cd and also to evaluate the impacts of these chelators (EDTA and citric acid) in combination with all the four heavy metals on the growth of marigold. The plants were grown in pots and treated with Zn (7.3 mg l(-1)), Cu (7.5 mg I(-1)), Pb (3.7 mg l(-1)) and Cd (0.2 mg l(-1)) alone and in combination with different doses of EDTA i.e., 10, 20 and 30 mg l(-1). All the three doses of EDTA i.e., 10, 20 and 30 mg l(-1) significantly increased the accumulation of Zn, Cu, Pb and Cd by roots, stems and leaves as compared to control treatments. The 30 mg l(-1) concentration of citric acid showed reduced accumulation of these metals by root, stem and leaves as compared to lower doses i.e., 10 and 20 mg l(-1). Among the four heavy metals, Zn accumulated in the great amount (526.34 mg kg(-1) DW) followed by Cu (443.14 mg kg(-1) DW), Pb (393.16 mg kg(-1) DW) and Cd (333.62 mg kg(-1) DW) in leaves with 30 mg l(-1) EDTA treatment. The highest concentration of EDTA and citric acid (30 mg l(-1)) caused significant reduction in growth of marigold in terms of plant height, fresh weight of plant, total chlorophyll, carbohydrate content and protein content. Thus EDTA and citric acid efficiently increased the phytoextractability of marigold which can be used to remediate the soil contaminated with these metals.

  1. Spectroscopy study of Zn, Cd, Pb and Cr ions immobilization on C-S-H phase.

    PubMed

    Żak, Renata; Deja, Jan

    2015-01-01

    Calcium silicate hydrates (C-S-H) have a large number of structural sites available for cations and anions to bind. The C-S-H phases are materials which have ability to toxic ions immobilization. Immobilization mechanisms for C-S-H include sorption, phase mixing, substitution and precipitation of insoluble compounds. This study presents the C-S-H (prepared with C/S ratios 1.0) phase as absorbent for immobilization of Zn, Cd, Pb and Cr ions. The C-S-H spectra before and after incorporation of heavy metals ions into the C-S-H structure were obtained. The effect of added heavy metals ions on the hydration phenomena was studied by means of X-ray diffractions analysis. FTIR spectra was measured. The microstructure and phase composition of C-S-H indicate that they can play an essential role in the immobilization of heavy metals. The properties of C-S-H in the presence of Zn, Cd, Pb and Cr cations were studied. The leaching ML test was used to evaluate the level of immobilization of heavy metals in C-S-H. The leached solutions are diluted and analyzed using atomic absorption spectrometry (AAS) and the activated solid particles are separated, washed, desiccated and analyzed by Fourier transform infrared (FTIR) spectroscopy. It was found that the degree of Cd, Zn, Pb and Cr cations immobilization was very high (exceeding 99.96%).

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

    PubMed

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

    2016-09-01

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

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

    PubMed

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

    2016-09-01

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

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

    PubMed

    Aboughalma, Hanssan; Bi, Ran; Schlaak, Michael

    2008-07-01

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

  5. Physiological responses and detoxific mechanisms to Pb, Zn, Cu and Cd in young seedlings of Paulownia fortunei.

    PubMed

    Wang, Jiang; Li, Weihua; Zhang, Chongbang; Ke, Shisheng

    2010-01-01

    Paulownia fortunei has been successfully used in the phytoremediation of many Pb/Zn mine tailings. However, seed germination and young seedlings of P. fortunei rarely occurred in these mine tailings. The physiological responses and detoxific mechanisms of P. fortunei young seedling to Pb, Zn, Cu and Cd stress were investigated. The germinated rate, shoot length, chlorophyll and carotenoid contents in leaves of young seedlings had a great reduction under Zn and Cu treatments, but had little decrease under Pb and Cd treatments. The production rate of O2*-, H2O2 and malondialdehyde (MDA) contents significantly increased in response to added Zn and Cu indicating great oxidative stress for young seedlings, but they had no significant change to added Pb and Cd. Young seedlings had effective detoxific mechanism to Pb and Cd, as antioxidant enzymes activities, phytochelatins (PCs-SH) and proline contents increased with increasing rates of added Pb and Cd. However, young seedlings had un-effective detoxific mechanisms to Zn and Cu stress. Results revealed the heavy metals (such as Cu) that present at low concentrations in mine tailings may be major constraint for the survival of young seedlings. PMID:21462710

  6. Sorption behavior of Cd, Cu, Pb, and Zn and their interactions in phytoremediated soil.

    PubMed

    Trakal, L; Komárek, M; Száková, J; Tlustos, P; Tejnecký, V; Drábek, O

    2012-09-01

    The aim of our study was to compare the sorption properties of a contaminated soil before and after two types of phytoremediation (natural phytoextraction vs. phytostabilization with dolomite limestone (DL) application). Soil from a pot experiment in controlled greenhouse conditions performed for two vegetation periods was used for the study. Lead, as the main contaminant in the studied soil, was easily desorbed by Cu, especially due to the increased affinity of Cu for soil organic matter; hence input of Cu to the studied soil can present another environmental risk in soils contaminated with other metals (such as Pb). In addition, the sorption behavior of chosen metals from single-element solutions differed from multielement solutions. The obtained results proved the different sorption behavior of metals in the single-element solution compared to the multi-element ones. Soil sorption behavior of Cd, Cu, and Zn decreased with the presence of the competitive metals; nevertheless, Pb sorption potential was not influenced by other competitive metals. Natural phytoextraction showed no significant effect on the sorption of Cd, Cu, Pb, and Zn onto the soil On the other hand, phytostabilization associated with DL application improved the soil sorption efficiency of all chosen metals, especially of Cu.

  7. Heavy metal (Cd, Pb, Zn) and metalloid (As) content in raptor species from Galicia (NW Spain).

    PubMed

    Pérez-López, Marcos; Hermoso de Mendoza, María; López Beceiro, Ana; Soler Rodríguez, Francisco

    2008-05-01

    As top consumers in food chains, birds of prey forage over large geographical areas and so might be expected to accumulate environmental contaminants which are distributed in the environment. These wild animals can offer opportunities to detect and assess the toxicological effects of different inorganic elements on terrestrial ecosystems. In this study, different raptor species, both diurnal and nocturnal, were investigated for heavy metal (Pb, Cd and Zn) and As concentrations in liver samples, with the aim of furnishing indirect information concerning contamination of their habitats. Dead animals were obtained with the special collaboration of the Wildlife Rehabilitation Centres from Galicia (NW Spain). After sample wet digestion, metal analysis was performed by inductively coupled plasma-mass spectrometry (ICP-MS). Hepatic concentrations of Zn and As, respectively, situated on the interval 147-298 and 1.21-6.88 ppm (dry weight, dw), could be considered as indicative of low and background amounts of both elements, with no ecotoxicological concern. Nevertheless, with respect to Pb, some diurnal raptors showed hepatic concentrations above the considered threshold value (6 ppm dw) for sublethal or lethal toxicity, the species with the highest hepatic level corresponding to a common buzzard (>18 ppm, dw). Similarly, nocturnal raptors exceeded the threshold value for Cd (3 ppm dw), with a maximum corresponding to an individual barn owl (39 ppm, dw). In both cases, although concentrations could not be directly related to lethal effect, they might constitute a serious environmental factor affecting the survival of the considered populations. PMID:17617459

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

    NASA Astrophysics Data System (ADS)

    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

  9. Distribution and evolution of Zn, Cd, and Pb in Apollo 16 regolith samples and the average U-Pb ages of the parent rocks

    NASA Technical Reports Server (NTRS)

    Cirlin, E. H.; Housley, R. M.

    1982-01-01

    The concentration of surface (low temperature site) and interior (high temperature site) Cd, Zn, and Pb in 13 Apollo 16 highland fines samples, pristine rock 65325, and mare fines sample 75081 were analyzed directly from the thermal release profiles obtained by flameless atomic absorption technique (FLAA). Cd and Zn in pristine ferroan anothosite 65325, anorthositic grains of the most mature fines 65701, and basaltic rock fragments of mare fines 75081 were almost all surface Cd and Zn indicating that most volatiles were deposited on the surfaces of vugs, vesicles and microcracks during the initial cooling process. A considerable amount of interior Cd and Zn was observed in agglutinates. This result suggests that high temperature site interior volatiles originate from entrapment during the lunar maturation processes. Interior Cd found in the most mature fines sample 65701 was only about 15% of the total Cd in the sample. Interior Pb present in Apollo 16 fines samples went up to 60%. From our Cd studies we can assume that this interior Pb in highland fines samples is largely due to the radiogenic decay which occurred after the redistribution of the volatiles took place. We obtained an average age of 4.0 b.y. for the parent rocks of Apollo 16 highland regolith from our interior Pb analyses.

  10. Trace level determination of u, zn, cd, pb and cu in drinking water samples.

    PubMed

    Kumar, Mukesh; Singh, Surinder; Mahajan, Rakesh Kumar

    2006-01-01

    The concentration of uranium has been assessed in drinking water samples collected from different locations in Bathinda district, Punjab, India. The water samples are taken from hand pumps and tube wells. Uranium is determined using fission track technique. Uranium concentration in the water samples varies from 2.23+/- 0.05 to 87.05+/- 0.29 microg/L. These values are compared with safe limit values recommended for drinking water. The uranium concentration in almost all drinking water samples is found to be more than the safe limit. Analysis of some heavy metals viz. Zn, Cd, Pb and Cu in water is made. The concentration of sodium, potassium, calcium, magnesium, chlorine and total hardness along with the pH value and conductivity of the water samples are measured. Some of the samples show stunningly high values of these parameters.

  11. Impact of spiked concentrations of Cd, Pb, As and Zn in growth medium on elemental uptake of Nasturtium officinale (Watercress).

    PubMed

    Gounden, Denisha; Kisten, Kimona; Moodley, Roshila; Shaik, Shakira; Jonnalagadda, Sreekantha B

    2016-01-01

    This study is aimed at investigating the impact of water quality on the uptake and distribution of three non-essential and toxic elements, namely, As, Cd and Pb in the watercress plant to assess for metal toxicity. The plant was hydroponically cultivated under greenhouse conditions, with the growth medium being spiked with varying concentrations of As, Cd and Pb. Plants that were harvested weekly for elemental analysis showed physiological and morphological symptoms of toxicity on exposure to high concentrations of Cd and Pb. Plants exposed to high concentrations of As did not survive and the threshold for As uptake in watercress was established at 5 ppm. Translocation factors were low in all cases as the toxic elements accumulated more in the roots of the plant than the edible leaves. The impact of Zn on the uptake of toxic elements was also evaluated and Zn was found to have an antagonistic effect on uptake of both Cd and Pb with no notable effect on uptake of As. The findings indicate that phytotoxicity or death of the watercress plant would prevent it from being a route of human exposure to high concentrations of As, Cd and Pb in the environment. PMID:26479037

  12. Impact of spiked concentrations of Cd, Pb, As and Zn in growth medium on elemental uptake of Nasturtium officinale (Watercress).

    PubMed

    Gounden, Denisha; Kisten, Kimona; Moodley, Roshila; Shaik, Shakira; Jonnalagadda, Sreekantha B

    2016-01-01

    This study is aimed at investigating the impact of water quality on the uptake and distribution of three non-essential and toxic elements, namely, As, Cd and Pb in the watercress plant to assess for metal toxicity. The plant was hydroponically cultivated under greenhouse conditions, with the growth medium being spiked with varying concentrations of As, Cd and Pb. Plants that were harvested weekly for elemental analysis showed physiological and morphological symptoms of toxicity on exposure to high concentrations of Cd and Pb. Plants exposed to high concentrations of As did not survive and the threshold for As uptake in watercress was established at 5 ppm. Translocation factors were low in all cases as the toxic elements accumulated more in the roots of the plant than the edible leaves. The impact of Zn on the uptake of toxic elements was also evaluated and Zn was found to have an antagonistic effect on uptake of both Cd and Pb with no notable effect on uptake of As. The findings indicate that phytotoxicity or death of the watercress plant would prevent it from being a route of human exposure to high concentrations of As, Cd and Pb in the environment.

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

    PubMed

    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).

  14. Effects of heavy metals (Cd, Cu, Cr, Pb, Zn) on fish glutathione metabolism.

    PubMed

    Eroglu, A; Dogan, Z; Kanak, E G; Atli, G; Canli, M

    2015-03-01

    The glutathione metabolism contains crucial antioxidant molecules to defend the organisms against oxidants. Thus, the aim of this study was to investigate the response of the glutathione metabolism in the liver of freshwater fish Oreochromis niloticus exposed to metals (Cu, Cd, Cr, Pb, Zn) in different periods. Fish were exposed to metals (as 1 μg/mL) individually for 1, 7, and 14 days and subsequently antioxidant enzymes (glutathione peroxidase, GPX; glutathione reductase, GR and glutathione S-transferase, GST) and glutathione levels (total glutathione, tGSH; reduced glutathione, rGSH; oxidized glutathione, GSSG and GSH/GSSG ratios) in the liver were measured. There was no fish mortality during the experiments, except Cu exposure. The antioxidant enzymes responded differently to metal exposures depending on metal types and exposure durations. GPX activity increased only after Cd exposure, while GST activity increased following 7 days of all metal exposures. However, GR activity did not alter in most cases. Total GSH and GSH/GSSG levels generally decreased, especially after 7 days. Data showed that metal exposures significantly altered the response of antioxidant system parameters, particularly at day 7 and some recovery occurred after 14 days. This study suggests that the response of antioxidant system could help to predict metal toxicity in the aquatic environments and be useful as an "early warning tool" in natural monitoring studies.

  15. The effects of biochars from rice residue on the formation of iron plaque and the accumulation of Cd, Zn, Pb, As in rice (Oryza sativa L.) seedlings.

    PubMed

    Zheng, Rui-Lun; Cai, Chao; Liang, Jian-Hong; Huang, Qing; Chen, Zheng; Huang, Yi-Zong; Arp, Hans Peter H; Sun, Guo-Xin

    2012-10-01

    A historically multi-metal contaminated soil was amended with biochars produced from different parts of rice plants (straw, husk and bran) to investigate how biochar can influence the mobility of Cd, Zn, Pb and As in rice seedlings (Oryza sativa L.). Rice shoot concentrations of Cd, Zn and Pb decreased by up to 98%, 83% and 72%, respectively, due to biochar amendment, though that of As increased by up to 327%. Biochar amendments significantly decreased pore water concentrations (C(pw)) of Cd and Zn and increased that of As. For Pb it depended on the amendment. Porewater pH, dissolved organic carbon, dissolved phosphorus, silicon in pore water and iron plaque formation on root surfaces all increased significantly after the amendments. The proportions of Cd and Pb in iron plaque increased by factors 1.8-5.7 and 1.4-2.8, respectively; no increase was observed for As and Zn. Straw-char application significantly and noticeably decreased the plant transfer coefficients of Cd and Pb. This study, the first to investigate changes in metal mobility and iron plaque formation in rice plants due to amending a historically contaminated soil with biochar, indicates that biochar has a potential to decrease Cd, Zn and Pb accumulations in rice shoot but increase that of As. The main cause is likely biochar decreasing the C(pw) of Cd and Zn, increasing the C(pw) of As, and increasing the iron plaque blocking capacity for Cd and Pb. PMID:22664390

  16. Effects of grinding and shaking on Cd, Pb and Zn distribution in anthropogenically impacted soils.

    PubMed

    Waterlot, Christophe; Bidar, Géraldine; Pruvot, Christelle; Douay, Francis

    2012-08-30

    The effects of grinding size and shaking process on the results of Cd (cadmium), Pb (lead) and Zn (zinc) distribution measurements three agricultural and three kitchen garden soils highly contaminated by past atmospheric fallout of two lead and zinc smelters in northern France were studied. The physico-chemical parameters and pseudo-total concentration of metals within these soils were determined. The fractionation of metals was performed in triplicate, using the procedure recommended by the Standards, Measurements and Testing program (SM&T), on each air-dried soil sample, ground to pass through 2-mm, 0.315-mm and 0.250-mm sieves and using a reciprocating or rotary shaker. The samples were analysed by flame or electrothermal absorption atomic spectrometry using a self-reversal background system. For both shaking processes, the grinding size had no effect on the fractionation of metals in contaminated agricultural soils. In contrast, using a reciprocating shaker, the fractionation of metals in the kitchen garden samples sieved at <2mm was so different that in the samples prepared to pass through the 0.315-mm and 0.250-mm sieves. Therefore changes (use of a 50 mL graduated polypropylene centrifuge tube, evaporation of the solution to a fixed volume in step 3 and the use of an automatic shaking heating bath) were made to the initial procedure and a rotary shaker was used to improve the suspension of the soil samples during extraction. For all grinding sizes, the fractionation of the three metals contained in the contaminated kitchen garden soil samples was successfully achieved. Nevertheless, some discrepancies from samples sieved at <2mm were obtained. On the other hand, it is worth noting that the effect of the type of shaker on the distribution of metal depended on the soil and the grinding size. From an analytical point of view, precision and trueness were improved after optimisation of the procedure for all sequential extraction procedure steps. The best results

  17. Effects of grinding and shaking on Cd, Pb and Zn distribution in anthropogenically impacted soils.

    PubMed

    Waterlot, Christophe; Bidar, Géraldine; Pruvot, Christelle; Douay, Francis

    2012-08-30

    The effects of grinding size and shaking process on the results of Cd (cadmium), Pb (lead) and Zn (zinc) distribution measurements three agricultural and three kitchen garden soils highly contaminated by past atmospheric fallout of two lead and zinc smelters in northern France were studied. The physico-chemical parameters and pseudo-total concentration of metals within these soils were determined. The fractionation of metals was performed in triplicate, using the procedure recommended by the Standards, Measurements and Testing program (SM&T), on each air-dried soil sample, ground to pass through 2-mm, 0.315-mm and 0.250-mm sieves and using a reciprocating or rotary shaker. The samples were analysed by flame or electrothermal absorption atomic spectrometry using a self-reversal background system. For both shaking processes, the grinding size had no effect on the fractionation of metals in contaminated agricultural soils. In contrast, using a reciprocating shaker, the fractionation of metals in the kitchen garden samples sieved at <2mm was so different that in the samples prepared to pass through the 0.315-mm and 0.250-mm sieves. Therefore changes (use of a 50 mL graduated polypropylene centrifuge tube, evaporation of the solution to a fixed volume in step 3 and the use of an automatic shaking heating bath) were made to the initial procedure and a rotary shaker was used to improve the suspension of the soil samples during extraction. For all grinding sizes, the fractionation of the three metals contained in the contaminated kitchen garden soil samples was successfully achieved. Nevertheless, some discrepancies from samples sieved at <2mm were obtained. On the other hand, it is worth noting that the effect of the type of shaker on the distribution of metal depended on the soil and the grinding size. From an analytical point of view, precision and trueness were improved after optimisation of the procedure for all sequential extraction procedure steps. The best results

  18. 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.

    PubMed

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

    2006-01-01

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

  19. Relation of pH and other soil variables to concentrations of Pb, Cu, Zn, Cd, and Se in earthworms

    USGS Publications Warehouse

    Beyer, W.N.; Hensler, G.L.; Moore, J.

    1987-01-01

    Various soil treatments (clay, composted peat, superphosphate, sulfur, calcium carbonate, calcium chloride, zinc chloride, selenous acid) were added to experimental field plots to test the effect of different soil variables on the concentrations of 5 elements in earthworms (Pb, Cu, Zn, Cd, Se). Concentrations of the 5 elements were related to 9 soil variables (soil Pb, soil Cu, soil Zn, pH, organic matter, P, K, Mg, and Ca) with linear multiple regression. Lead concentrations in earthworms were positively correlated with soil Pb and soil organic matter, and negatively correlated with soil pH and soil Mg, with an R2 of 64%. Se concentrations were higher in earthworms from plots amended with Se, and Zn concentrations were higher in earthworms from plots amended with Zn. However, none of the other soil variables had important effects on the concentrations of Cu, Zn, Cd and Se in earthworms. Although some significant statistical relations were demonstrated, the values of r2 of all relations (> 20%) were so low that they had little predictive value.

  20. Use of bone meal amendments to immobilise Pb, Zn and Cd in soil: A leaching column study.

    PubMed

    Sneddon, I R; Orueetxebarria, M; Hodson, M E; Schofield, P F; Valsami-Jones, E

    2006-12-01

    The aim of this study is to test the stabilisation of metals in contaminated soils via the formation of low-solubility metal phosphates. Bone apatite, in the form of commercially available bone meal, was tested as a phosphate source on a mine waste contaminated made-ground with high levels of Pb, Zn and Cd. Triplicate leaching columns were set up at bone meal to soil ratios of 1:25 and 1:10, in addition to unamended controls, and were run for 18 months. The columns were irrigated daily with a synthetic rain solution at pH of 2, 3, and 4.4. After 100 days, the leachate Pb, Zn and Cd concentrations of all amended columns were significantly reduced. For 1:10 treatments, release of these metals was suppressed throughout the trial. For 1:25 treatments, Zn and Cd concentrations in the leachates began to increase after 300 days. DTPA and water extractions showed that Pb and Cd were more strongly held in the amended soils. This study concludes that the complexity of soil processes and the small quantities of metals sequestered precluded determination of a metal immobilisation mechanism.

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

    PubMed

    Komjarova, I; Blust, R

    2008-11-11

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

  2. Removal of As, Cd, Cu, Ni, Pb, and Zn from a highly contaminated industrial soil using surfactant enhanced soil washing

    NASA Astrophysics Data System (ADS)

    Torres, Luis G.; Lopez, Rosario B.; Beltran, Margarita

    Surfactant enhanced soil washing (SESW) was applied to an industrial contaminated soil. A preliminary characterization of the soil regarding the alkaline-earth metals, Na, K, Ca and Mg took values of 2866, 2036, 2783 and 4149 mg/kg. The heavy metals As, Cd, Cu, Pb, Ni and Zn, had values of 4019, 14, 35582, 70, 2603, and 261 mg/kg, respectively. When using different surfactants, high removal of Cu, Ni and Zn were found, and medium removals for Pb, As and Cd. In the case of these three metals, tap water removed more than the surfactant solutions, except for the case of As. There were surfactants with average removals (this is, the removal for all the metals studied) of 67.1% (Tween 80), 64.9% (Surfacpol 14104) and 61.2% (Emulgin W600). There were exceptional removals using Texapon N-40 (83.2%, 82.8% and 86.6% for Cu, Ni and Zn), Tween 80 (85.9, 85.4 and 81.5 for Cd, Zn and Cu), Polafix CAPB (79%, 83.2% and 49.7% for Ni, Zn and As). The worst results were obtained with POLAFIX LO with a global removal of 45%, well below of the average removal with tap water (50.2%).All removal efficiencies are reported for a one step washing using 0.5% surfactant solutions, except for the case of mezquite gum, where a 0.1% solution was employed.

  3. Mass spectrometry and potentiometry studies of Pb(II)-, Cd(II)- and Zn(II)-cystine complexes.

    PubMed

    Furia, Emilia; Aiello, Donatella; Di Donna, Leonardo; Mazzotti, Fabio; Tagarelli, Antonio; Thangavel, Hariprasad; Napoli, Anna; Sindona, Giovanni

    2014-01-21

    Cd(II)-, Pb(II)- and Zn(II)-cystine complexes were investigated by potentiometric and different mass spectrometric (MS) methodologies. Laser desorption mass spectrometry has provided both the composition and structure of metal-cystine complexes according to the speciation models proposed on the basis of the potentiometric data. Detection of neutral complexes was achieved by protonation or electrochemical reduction during mass spectrometric experiments. The redox activity of metal-cystine complexes was confirmed by laser desorption and charge transfer matrix assisted laser assisted MS experiments, which allowed us to observe the formation of complexes with a reduction of cystine. The stoichiometry of Cd(II)-, Pb(II)- and Zn(II)-cystine complexes was defined by observing the isotopic pattern of the investigated compound. The results suggest that interaction occurs through the carboxylate group of the ligand.

  4. Kinetic rate laws of Cd, Pb, and Zn vaporization during municipal solid waste incineration.

    PubMed

    Falcoz, Quentin; Gauthier, Daniel; Abanades, Stéphane; Flamant, Gilles; Patisson, Fabrice

    2009-03-15

    The kinetic rate laws of heavy metal (HM) vaporization from municipal solid waste during its incineration were studied. Realistic artificial waste (RAW) samples spiked with Pb, Zn, and Cd were injected into a fluidized bed reactor. Metal vaporization wastracked by continuous measure ofthe above metals in exhaust gases. An inverse model of the reactor was used to calculate the metal vaporization rates from the concentration vs time profiles in the outlet gas. For each metal, experiments were carried out at several temperatures in order to determine the kinetic parameters and to obtain specific rate laws as functions of temperature. Temperature has a strong influence on the HM vaporization dynamics, especially on the vaporization kinetics profile. This phenomenon was attributed to internal diffusion control of the HM release. Two types of kinetic rate laws were established based on temperature: a fourth- or fifth-order polynomial rate law (r(x) = k0e(-E(A)/RT)p(x)) for temperatures lower than 740 degrees C and a first-order polynomial (r(x) = k0e(-E(A)/ RT(q-q(f) for temperatures higher than 740 degrees C.

  5. Mineral transformations and Zn, Pb, As, Cd mobility in soils developed on Zn non-sulfide mining wastes near Olkusz, S Poland

    NASA Astrophysics Data System (ADS)

    Jerzykowska, Irena; Michalik, Marek

    2014-05-01

    To estimate the degree of threat posed by heavy metals and other environmentally harmful elements it is necessary to determine forms in which these elements occur and their stability in the weathering environment. The aim of this work was to (1) describe mineral transformations occurring in soils developed on Zn non-sulfide mining wastes near Olkusz (S Poland), (2) identify forms of occurrence of Zn, Pb, As, Cd; and (3) predict potential mobility of these elements. Studied samples come from soil profiles developed on four dumps after mining of non-sulfide Zn ores from the end of the XIX century until 1985. Two types of approaches were used: mineralogical methods (optical and electron microscopy with in situ elemental analysis, X-ray diffraction) and geochemical methods (selective sequential extraction and bulk elemental analysis). Zn in studied samples is present in smithsonite or hemimorphite, Zn aluminosilicates (smectite and kaolinite groups) and absorbed on Fe-oxide. The largest amounts of Pb is encountered in Mn-oxides and less in cerrusite, Fe-oxides and dolomite. As dominates as the ions absorbed on goethite and Cd as an impurity in carbonates, silicates and Zn-aluminosilicates, and in the form of exchangeable ions. Most important mineral transformations due to weathering observed in the samples are dissolution of dolomite, goethite, smithsonite, hemimorphite and precipitation of Zn-aluminosilicates, Mn-oxides and secondary Fe-oxides. The study has shown that Cd occurring in the form of exchangeable ions, potentially available to living organisms, pose the greatest threat to the environment. Cd is the most mobile in surface horizons of the soils developed on the oxidized ores dumps. Zn and Pb can be released from their forms in the event of a change of pH of the environment to a more acidic and As in case of changing conditions to more reductive.

  6. A survey of Pb, Cu, Zn, Cd, Cr, As, and Se in earthworms and soil from diverse sites.

    PubMed

    Beyer, W N; Cromartie, E J

    1987-01-01

    Earthworms and soils were collected from 20 diverse sites in Maryland, Pennsylvania, and Virginia, and were analyzed for Pb, Cu, Zn, Cd, Cr, As, and Se. Correlation coefficients relating concentrations of the elements in earthworms to concentrations in soil were low (-0.20Pb (2100 ppm), Zn (1600 ppm), Cd (23 ppm) and Se (7.6 ppm) detected in earthworms were in the range reported to be toxic to animals fed diets containing these elements; however, even in the absence of any environmental contamination, some species of earthworms may contain high concentrations of Pb, Zn, and Se. Earthworms of the genus Eisenoides, for example, were exceptional in their ability to concentrate Pb. When earthworms are used as indicators of environmental contamination, it is important to identify the species, to report the soil characteristics, and to collect similar earthworms from very similar but uncontaminated soil. PMID:24253769

  7. A survey of Pb, Cu, Zn, Cd, Cr, As, and Se in earthworms and soil from diverse sites

    USGS Publications Warehouse

    Beyer, W.N.; Cromartie, E.J.

    1987-01-01

    Earthworms and soils were collected from 20 diverse sites in Maryland, Pennsylvania, and Virginia, and were analyzed for Pb, Cu, Zn, Cd, Cr, As, and Se. Correlation coefficients relating Iconcentrations of the elements in earthworms to concentrations in soil were low (-0.20Pb (2100 ppm), Zn (1600 ppm), Cd (23 ppm) and Se (7.6 ppm) detected in earthworms were in the range reported to be toxic to animals fed diets containing these elements; however, even in the absence of any environmental contamination, some species of earthworms may contain high concentrations of Pb, Zn, and Se. Earthworms of the genus Eisenoides, for example, were exceptional in their ability to concentrate Pb. When earthworms are used as indicators of environmental contamination, it is important to identify the species, to report the soil characteristics, and to collect similar earthworms from very similar but uncontaminated soil.

  8. Bioaccessibility of Cd, Cu, Fe, Mn, Pb, and Zn in hazelnut and walnut kernels investigated by an enzymolysis approach.

    PubMed

    Arpadjan, Sonja; Momchilova, Svetlana; Venelinov, Tony; Blagoeva, Elitsa; Nikolova, Magdalena

    2013-06-26

    Bioaccessibility of four essential (Fe, Cu, Mn, Zn) and two toxic (Cd, Pb) elements in kernels of four walnut and four hazelnut cultivars was investigated using sequential enzymolysis approach and atomic absorption spectrometry. It was found that the assimilable part of elements was not dependent on nut cultivar. The bioaccessible fraction of Cu, Mn, and Zn was definitely higher for hazelnuts (62% Cu, 39% Mn, 58% Zn) than for walnuts (14% Cu, 21% Mn, 15% Zn). Bioaccessible Fe was 20-24% from its total content for both nut types. Solubility in the simulated intestinal juice is affected by both formation of stable soluble complexes and back sorption of dissolved elements on nut solid residues. Lead shows strong insolubility due to the high sorption affinity of lead ions to the insoluble fraction of nuts. Thus, walnuts and hazelnuts could act as effective biosorbents for lead detoxication.

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

    PubMed

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

    2014-01-01

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

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

    PubMed

    Szrek, Dominik; Bajda, Tomasz; Manecki, Maciej

    2011-01-01

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

  11. Impact of multi-metals (Cd, Pb and Zn) exposure on the physiology of the yeast Pichia kudriavzevii.

    PubMed

    Mesquita, Vanessa A; Machado, Manuela D; Silva, Cristina F; Soares, Eduardo V

    2015-07-01

    Metal contamination of the environment is frequently associated to the presence of two or more metals. This work aimed to study the impact of a mixture of metals (Cd, Pb and Zn) on the physiology of the non-conventional yeast Pichia kudriavzevii. The incubation of yeast cells with 5 mg/l Cd, 10 mg/l Pb and 5 mg/l Zn, for 6 h, induced a loss of metabolic activity (assessed by FUN-1 staining) and proliferation capacity (evaluated by a clonogenic assay), with a small loss of membrane integrity (measured by trypan blue exclusion assay). The staining of yeast cells with calcofluor white revealed that no modification of chitin deposition pattern occurred during the exposure to metal mixture. Extending for 24 h, the exposure of yeast cells to metal mixture provoked a loss of membrane integrity, which was accompanied by the leakage of intracellular components. A marked loss of the metabolic activity and the loss of proliferation capacity were also observed. The analysis of the impact of a single metal has shown that, under the conditions studied, Pb was the metal responsible for the toxic effect observed in the metal mixture. Intracellular accumulation of Pb seems to be correlated with the metals' toxic effects observed. PMID:25794581

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

    NASA Astrophysics Data System (ADS)

    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.

  13. Use of Solen brevis as a biomonitor for Cd, Pb and Zn on the intertidal zones of Bushehr-Persian Gulf, Iran.

    PubMed

    Salahshur, Sara; Bakhtiari, Alireza Riyahi; Kochanian, Preeta

    2012-06-01

    The concentrations of Zn, Cd and Pb were determined in tissues (shell and soft tissue) of 144 of bivalve mollusks (Solen brevis) and 15 samples of surface sediment collected from three locations in intertidal zones of Bushehr coast, Persian Gulf, Iran in May 2011. The mean concentrations of Zn, Cd and Pb in the sediment samples were 26.2, 1.25, and 21.1 μg/g dw, respectively. The mean levels of Zn, Cd and Pb in the clam samples were 63.3, 0.67, and 4.38 μg/g dw in soft tissue and 10. 7, 1.53, and 15.6 μg/g dw in shell, respectively. The degrees of variability (CV %) for Cd and Pb within the shells were lower than for soft tissues, whereas the CV for Zn was lower in the soft tissue than in the shell, indicating that there is more precision (lower CV) in the determination of Cd and Pb in the shells and Zn in the soft tissues. Significant correlation were found between Cd (r = 0.63; p < 0.05) and Pb (r = 0.78; p < 0.01) concentrations in the shell of S. brevis and their concentrations in the surface sediments. Indeed, Zn concentrations in the soft tissue of S. brevis significantly (r = 0.63; p < 0.05) correlated with Zn concentrations in surface sediments. The results of this study suggest that the shell of S. brevis may serve as a reliable biomonitor for Cd and Pb, and the soft tissue for Zn.

  14. Pb-Zn-Cd-Hg multi isotopic characterization of the Loire River Basin, France

    NASA Astrophysics Data System (ADS)

    Millot, R.; Widory, D.; Innocent, C.; Guerrot, C.; Bourrain, X.; Johnson, T. M.

    2012-12-01

    The contribution of human activities such as industries, agriculture and domestic inputs, becomes more and more significant in the chemical composition (major ions and pollutants such as metals) of the dissolved load of rivers. Furthermore, this influence can also be evidenced in the suspended solid matter known to play an important role in the transport of heavy metals through river systems. Human factors act as a supplementary key process. Therefore the mass-balance for the budget of catchments and river basins include anthropogenic disturbances. The Loire River in central France is approximately 1010 km long and drains an area of 117,800 km2. Initially, the Loire upstream flows in a south to north direction originating in the Massif Central, and continues up to the city of Orléans, 650 km from the source. In the upper basin, the bedrock is old plutonic rock overlain by much younger volcanic rocks. The Loire River then follows a general east to west direction to the Atlantic Ocean. The intermediate basin includes three major tributaries flowing into the Loire River from the left bank: the Cher, the Indre and the Vienne rivers; the main stream flows westward and its valley stretches toward the Atlantic Ocean. Here, the Loire River drains the sedimentary series of the Paris Basin, mainly carbonate deposits. The lower Loire basin drains pre-Mesozoic basement of the Armorican Massif and its overlying Mesozoic to Cenozoic sedimentary deposits. The Loire River is one of the main European riverine inputs to the Atlantic ocean. Here we are reporting concentration and isotope data for heavy metals Zn-Cd-Pb-Hg in river waters and suspended sediments from the Loire River Basin. In addition, we also report concentration and isotope data for these metals for the different industrial sources within the Loire Basin, as well as data for biota samples such as mussels and oysters from the Bay of Biscay and North Brittany. These organisms are known to be natural accumulators of

  15. Linking heavy metal bioavailability (Cd, Cu, Zn and Pb) in Scots pine needles to soil properties in reclaimed mine areas.

    PubMed

    Pietrzykowski, Marcin; Socha, Jarosław; van Doorn, Natalie S

    2014-02-01

    This work deals with bioaccumulation of Zn, Pb, Cu and Cd in foliage of Scots pine, grown on mine soils. Regression models were used to describe relationships between pine elements bioavailability and biological (dehydrogenase activity) and physico-chemical properties of mine soils developed at different parental rocks. Concentration of trace elements in post-mine ecosystems did not differ from data for Scots pine on natural sites. We conclude that, in this part of Europe in afforested areas affected by hard coal, sand, lignite and sulphur mining, there is no risk of trace element concentrations in mine soils. An exception was in the case of Cd in soils on sand quarry and hard coal spoil heap located in the Upper Silesia region, which was more due to industrial pressure and pollutant deposition than the original Cd concentration in parental rocks.

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

    PubMed

    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.

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

    PubMed

    Basile, A; Sorbo, S; Pisani, T; Paoli, L; Munzi, S; Loppi, S

    2012-07-01

    This paper tested if culturing the moss Scorpiurum circinatum (Brid.) Fleisch. & Loeske with metal solutions (Cd, Cu, Pb and Zn) for 30 days causes metal bioaccumulation and ultrastructural changes. The results showed that despite the high heavy metal concentrations in treatment solutions, treated samples did not show severe ultrastructural changes and cells were still alive and generally well preserved. Bioaccumulation highlighted that moss cells survived to heavy metal toxicity by immobilizing most toxic ions extracellularly, likely in binding sites of the cell wall, which is the main site of metal detoxification. PMID:22516710

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

    NASA Astrophysics Data System (ADS)

    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

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

    PubMed

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

    2016-10-01

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

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

    PubMed

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

    2016-10-01

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

  1. Effect of nitrate and ammonium fertilization on Zn, Pb, and Cd phytostabilization by Populus euramericana Dorskamp in contaminated technosol.

    PubMed

    Qasim, Bashar; Motelica-Heino, Mikael; Bourgerie, Sylvain; Gauthier, Arnaud; Morabito, Domenico

    2015-12-01

    This study aimed at assessing the effect of nitrogen addition under two forms, nitrate and ammonium, on the stabilization of Zn, Pb, and Cd by Populus euramericana Dorskamp grown in contaminated soils for 35 days under controlled conditions. Temporal changes in the soil pore water (SPW) were monitored for pH, dissolved organic carbon (DOC), and total dissolved concentrations of metals in the soils rhizosphere. Rhizospheric SPW pH decreased gradually with NH4(+) addition and increased with NO3(-) addition up to one unit, while it slightly decreased initially then increased for the untreated control soil DOC increased with time up to six times, the highest increase occurring with NH4(+) fertilization. An increase in the metal concentrations in the rhizospheric SPW was observed for NH4(+) addition associated with the lowest rhizospheric SPW pH, whereas the opposite was observed for the control soil and NO3(-) fertilization. Fertilization did not affect plant shoots or roots biomass development compared to the untreated control (without N addition). Metals were mostly accumulated in the rhizosphere and N fertilization increased the accumulation for Zn and Pb while Cd accumulation was enhanced for NH4(+) addition. Collectively, our results suggest metal stabilization by P. euramericana Dorskamp rhizosphere with nitrogen fertilization and are potential for phytostabilization of contaminated technosol.

  2. The spatial and temporal trends of Cd, Cu, Hg, Pb and Zn in Seine River floodplain deposits (1994-2000)

    USGS Publications Warehouse

    Grosbois, C.; Meybeck, Michel; Horowitz, A.; Ficht, A.

    2006-01-01

    Fresh floodplain deposits (FD), from 11 key stations, covering the Seine mainstem and its major tributaries (Yonne, Marne and Oise Rivers), were sampled from 1994 to 2000. Background levels for Cd, Cu, Hg, Pb, and Zn were established using prehistoric FD and actual bed sediments collected in small forested sub-basins in the most upstream part of the basin. Throughout the Seine River Basin, FD contain elevated concentrations of Cd, Cu, Hg, Pb and Zn compared to local background values (by factors > twofold). In the Seine River Basin, trace element concentrations display substantial downstream increases as a result of increasing population densities, particularly from Greater Paris (10 million inhabitants), and reach their maxima at the river mouth (Poses). These elevated levels make the Seine one of the most heavily impacted rivers in the world. On the other hand, floodplain-associated trace element levels have declined over the past 7 years. This mirrors results from contemporaneous suspended sediment surveys at the river mouth for the 1984-1999 period. Most of these temporal declines appear to reflect reductions in industrial and domestic solid wastes discharged from the main Parisian sewage plant (Seine Aval). ?? 2005 Elsevier B.V. All rights reserved.

  3. Effect of nitrate and ammonium fertilization on Zn, Pb, and Cd phytostabilization by Populus euramericana Dorskamp in contaminated technosol.

    PubMed

    Qasim, Bashar; Motelica-Heino, Mikael; Bourgerie, Sylvain; Gauthier, Arnaud; Morabito, Domenico

    2015-12-01

    This study aimed at assessing the effect of nitrogen addition under two forms, nitrate and ammonium, on the stabilization of Zn, Pb, and Cd by Populus euramericana Dorskamp grown in contaminated soils for 35 days under controlled conditions. Temporal changes in the soil pore water (SPW) were monitored for pH, dissolved organic carbon (DOC), and total dissolved concentrations of metals in the soils rhizosphere. Rhizospheric SPW pH decreased gradually with NH4(+) addition and increased with NO3(-) addition up to one unit, while it slightly decreased initially then increased for the untreated control soil DOC increased with time up to six times, the highest increase occurring with NH4(+) fertilization. An increase in the metal concentrations in the rhizospheric SPW was observed for NH4(+) addition associated with the lowest rhizospheric SPW pH, whereas the opposite was observed for the control soil and NO3(-) fertilization. Fertilization did not affect plant shoots or roots biomass development compared to the untreated control (without N addition). Metals were mostly accumulated in the rhizosphere and N fertilization increased the accumulation for Zn and Pb while Cd accumulation was enhanced for NH4(+) addition. Collectively, our results suggest metal stabilization by P. euramericana Dorskamp rhizosphere with nitrogen fertilization and are potential for phytostabilization of contaminated technosol. PMID:26199007

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

    PubMed

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

    2013-01-01

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

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

    PubMed

    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.

  6. Growth and metal accumulation in Porcellio scaber exposed to poplar litter from Cd-, Pb-, and Zn-contaminated sites.

    PubMed

    Godet, Jean-Philippe; Demuynck, Sylvain; Waterlot, Christophe; Lemière, Sébastien; Souty-Grosset, Catherine; Scheifler, Renaud; Douay, Francis; Leprêtre, Alain; Pruvot, Christelle

    2011-03-01

    This study aimed at determining, in the laboratory, the effects of poplar litter collected in woody habitats contaminated by heavy metals on growth and metal accumulation in the terrestrial isopod Porcellio scaber. Cd, Pb, and Zn pseudototal and CaCl(2)-extractable concentrations in litter types were determined using AAS. Juveniles were fed ad libitum, individually, for 28 days with four litter types presenting an increasing gradient of metal contamination. Individuals were weighed every week and metal body burdens were determined at the end of the experiment. From the first week until the end of the experiment, a decrease in P. scaber growth related to the increase of metal concentration in litter types was recorded. Significant correlations were observed between metal body burdens and metal concentrations in litter types. However, Cd accumulation in woodlice appeared to be related to the Cd/Zn concentration ratio in litter types. All these results showed the potential of weight gain in P. scaber as a suitable indicator for litter quality assessment with ecological relevance.

  7. Persisting impact of historical mining activity to metal (Pb, Zn, Cd, Tl, Hg) and metalloid (As, Sb) enrichment in sediments of the Gardon River, Southern France.

    PubMed

    Resongles, Eléonore; Casiot, Corinne; Freydier, Rémi; Dezileau, Laurent; Viers, Jérôme; Elbaz-Poulichet, Françoise

    2014-05-15

    In this study, we assessed past and present influence of ancient mining activity on metal(loid) enrichment in sediments of a former mining watershed (Gardon River, SE France), that is now industrialized and urbanized. A sedimentary archive and current sediments were characterized combining geochemical analyses, zinc isotopic analyses and sequential extractions. The archive was used to establish local geochemical background and recorded (i) increasing enrichment factors (EFs) for Pb, Zn, Cd, Tl, Hg, As and Sb throughout the industrial era, (ii) a contamination peak in 1976 attributed to a tailings dam failure, and (iii) current levels in 2002 and 2011 similar to those of 1969, except for Sb and Hg, reflecting a persisting contamination pattern. Inter-element relationships and spatial distribution of EF values of current sediments throughout the watershed suggested that both ancient and current contamination had a common origin for Pb, Zn, Cd, Tl and As related to the exploitation of Pb/Zn mineralization while old Sb mines and coal extraction area were the main sources for Sb and Hg respectively. This prevailing mining origin was reflected for Zn by a relatively uniform isotopic composition at δ(66)Zn=0.23 ± 0.03‰, although slight decrease from 0.23‰ to 0.18‰ was recorded from upstream to downstream sites along the river course in relation with the contribution of the lighter δ(66)Zn signature (~0.08‰) of acid mine drainage impacted tributaries. Results from sequential extractions revealed that the potential mobility of the studied metal(loid)s varied in the order SbZn, with an increase of the mobile pool for Cd, Pb, Zn and to a lesser extent for As and Tl associated to increased enrichment. Altogether, these results tend to demonstrate that ancient mining activity still contributes to metal enrichment in the sediments of the Gardon River and that some of these metals may be mobilized toward the water compartment.

  8. Heavy metal accumulations of 24 asparagus bean cultivars grown in soil contaminated with Cd alone and with multiple metals (Cd, Pb, and Zn).

    PubMed

    Zhu, Yun; Yu, Hui; Wang, Junli; Fang, Wei; Yuan, Jiangang; Yang, Zhongyi

    2007-02-01

    Crops grown in heavy metal contaminated soils are an important avenue for these toxic pollutants entering the human food chain. Information on how crops respond to soil contaminations of single versus multiple metals is scarce and much needed. This study investigated the accumulation of Cd by 24 cultivars of asparagus bean (Vigna unguiculata subsp. Sesquipedalis L., family Fabaceae) under a low level (0.8 mg kg-1) and a high level (11.8 mg kg-1) of Cd exposure in a garden experiment, and that in a field experiment with Cd, Pb, and Zn (1.2, 486, and 1114 mg kg-1, respectively) contaminated soil. Both experiments showed that there were highly significant variations among the tested cultivars in Cd accumulation by roots, stems, leaves, and fruits of asparagus bean. In the garden experiment, all cultivars under the low Cd exposure and 41.7% of the tested cultivars under the high Cd exposure bore fruits (pods) whose Cd concentrations were lower than 0.05 mg kg-1 fw and therefore were safe for consumption. In addition, the fruit Cd concentrations of cultivars with black seed coats were significantly lower than those with red or spotted seed coats. These results suggest that asparagus bean is a hypo-accumulator to Cd pollutant and the trait of Cd accumulation is genetic-dependent among cultivars. In the field experiment, correlation between fruit Cd and Pb concentrations was significantly positive (p < 0.05). Additional correlation analyses between two experiments showed that fruit Cd concentrations in the field experiment were significantly correlated with those exposed to the high level of Cd stress, instead of to the low level of Cd stress in the garden experiment. This suggests that the presence of other toxic heavy metals in the soil might have facilitated the accumulation of Cd in fruits, and the selection of pollution-safe-cultivars (PSC) in multi-metal polluted condition could refer to the PSCs selected under a high level exposure of a single heavy metal.

  9. Toxicity Induced by a Metal Mixture (Cd, Pb and Zn) in the Yeast Pichia kudriavzevii: The Role of Oxidative Stress.

    PubMed

    Mesquita, Vanessa A; Silva, Cristina F; Soares, Eduardo V

    2016-05-01

    The present work aims to contribute for the elucidation of the role of oxidative stress in the toxicity associated with the exposure of Pichia kudriavzevii to multi-metals (Cd, Pb and Zn). Cells of the non-conventional yeast P. kudriavzevii exposed for 6 h to the action of multi-metals accumulated intracellular reactive oxygen species (ROS), evaluated through the oxidation of the probe 2',7'-dichlorodihydrofluorescein diacetate. A progressive loss of membrane integrity (monitored using propidium iodide) was observed in multi-metal-treated cells. The triggering of intracellular ROS accumulation preceded the loss of membrane integrity. These results suggest that the disruption of membrane integrity can be attributed to the oxidative stress. The exposure of yeast cells to single metal showed that, under the concentrations tested, Pb was the metal responsible for the induction of the oxidative stress. Yeast cells coexposed to an antioxidant (ascorbic acid) and multi-metals did not accumulate intracellular ROS, but loss proliferation capacity. Together, the data obtained indicated that intracellular ROS accumulation contributed to metal toxicity, namely for the disruption of membrane integrity of the yeast P. kudriavzevii. It was proposed that Pb toxicity (the metal responsible for the toxic symptoms under the conditions tested) result from the combination of an ionic mechanism and the intracellular ROS accumulation. PMID:26781618

  10. Decrease of Zn, Cd and Pb concentrations in marine fish species over a decade as response to reduction of anthropogenic inputs: the example of Tagus estuary.

    PubMed

    Raimundo, Joana; Pereira, Patrícia; Caetano, Miguel; Cabrita, Maria Teresa; Vale, Carlos

    2011-12-01

    Concentrations of Zn, Cd and Pb were measured in muscle of pelagic, demersal and benthic fishes, captured in the coastal area adjoining the Tagus estuary (Portugal), in 1998 and 2010. Additionally, Pb and Cd were determined in estuarine waters, showing a pronounced decrease between 1999 and 2010. Accordingly, specimens captured in 2010 presented significantly lower metal concentrations than individuals caught in 1998. Reductions were more evident for Pb (reduction of 59-99%) than for Cd (14-93%) and Zn (17-54%). Values in pelagic and demersal species exhibited higher reductions than in benthic species. Decrease of metal concentrations in fish appears thus to reflect the improvement of estuarine water quality as anthropogenic sources have been reduced or eliminated. Furthermore, it emphasises the usefulness of the descriptor "Contaminants in Fish" to assess the efficiency of measures to achieve a good environmental status, in the scope of the Marine Strategy Framework Directive.

  11. CORRELATION OF THE PARTITIONING OF DISSOLVED ORGANIC MATTER FRACTIONS WITH THE DESORPTION OF CD, CU, NI, PB AND ZN FROM 18 DUTCH SOILS

    EPA Science Inventory

    Eighteen Dutch soils were extracted in aqueous solutions at varying pH. Extracts were analyzed for Cd, Cu, Ni, Pb and Zn by ICP-AES. Extract dissolved organic carbon (DOC) was also concentrated onto a macroreticular resin and fractionation into three operationally defined fract...

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

    ERIC Educational Resources Information Center

    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…

  13. Distribution, mobility, and pollution assessment of Cd, Cu, Ni, Pb, Zn, and Fe in intertidal surface sediments of Sg. Puloh mangrove estuary, Malaysia.

    PubMed

    Udechukwu, Bede Emeka; Ismail, Ahmad; Zulkifli, Syaizwan Zahmir; Omar, Hishamuddin

    2015-03-01

    Sungai Puloh mangrove estuary supports a large diversity of macrobenthic organisms and provides social benefits to the local community. Recently, it became a major recipient of heavy metals originating from industries in the hinterland as a result of industrialization and urbanization. This study was conducted to evaluate mobility and pollution status of heavy metals (Cd, Cu, Ni, Pb, Zn, and Fe) in intertidal surface sediments of this area. Surface sediment samples were collected based on four different anthropogenic sources. Metals concentrations were analyzed using an atomic absorption spectrophotometer (AAS). Results revealed that the mean concentrations were Zn (1023.68 ± 762.93 μg/g), Pb (78.8 ± 49.61 μg/g), Cu (46.89 ± 43.79 μg/g), Ni (35.54 ± 10.75 μg/g), Cd (0.94 ± 0.29 μg/g), and Fe (7.14 ± 0.94%). Most of the mean values of analyzed metals were below both the interim sediment quality guidelines (ISQG-low and ISQG-high), except for Pb concentration (above ISQG-low) and Zn concentration (above ISQG-high), thus suggesting that Pb and Zn may pose some environmental concern. Cadmium, Pb, and Zn concentrations were above the threshold effect level (TEL), indicating seldom adverse effect of these metals on macrobenthic organisms. Pollution load index (PLI) indicated deterioration and other indices revealed the intertidal surface sediment is moderately polluted with Cd, Pb, and Zn. Therefore, this mangrove area requires urgent attention to mitigate further contamination. Finally, this study will contribute to data sources for Malaysia in establishing her own ISQG since it is a baseline study with detailed contamination assessment indices for surface sediment of intertidal mangrove area. PMID:25292304

  14. In-situ stabilization of Pb, Zn, Cu, Cd and Ni in the multi-contaminated sediments with ferrihydrite and apatite composite additives.

    PubMed

    Qian, Guangren; Chen, Wei; Lim, Teik Thye; Chui, Pengcheong

    2009-10-30

    Three additives were evaluated for their effectiveness in the attenuation of Pb2+, Zn2+, Cu2+, Cd2+, Ni2+ in contaminated sediments. Apatite, ferrihydrite and their composite were applied to the sediments. For the remediation, BCR, SEM/AVS and TCLP were adopted as the evaluating method and comparison of their results were used for the first time to test in-situ stabilization effect. The results showed that after 5 months composite treatment, more than 70% Pb2+, 40% Zn2+, 90% Cu2+, 50% Cd2+ and 80% Ni2+ was immobilized in oxidizable and residual phases, respectively. Compared to untreated sediment, Pb2+, Zn2+, Cu2+, Cd2+ in residual fraction increased 20%, 10%, 10%, 10% with composite treatment after 5 months, respectively. SigmaSEM/AVS ratio declined from 12.6 to 9.3, in addition, composite treatments reduced the leaching of Pb2+ and Zn2+ from 10.6 mg L(-1) and 42.5 mg L(-1) to 5.4 mg L(-1) and 24.1 mg L(-1) in the sediment by TCLP evaluation. Meanwhile, apatite and ferrihydrite composite additives lowered the bioavailability and toxicity of sediments as well. Ferrihydrite had a positive effect in controlling the bioavailability and toxicity of heavy metals because it effectively retarded the oxidation of AVS in sediment. PMID:19564075

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

    PubMed

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

    2016-01-01

    Biochar is a carbon-rich solid material derived from the pyrolysis of agricultural and forest residual biomass. Previous studies have shown that biochar is suitable as an adsorbent for soil contaminants such as heavy metals and consequently reduces their bioavailability. However, the long-term effect of different biochars on metal extractability or soil health has not been assessed. Therefore, a 1-year incubation experiment was carried out to investigate the effect of biochar produced from bamboo and rice straw (at temperatures ≥500 °C) on the heavy metal (cadmium (Cd), copper (Cu), lead (Pb), and zinc (Zn)) extractability and enzyme activity (urease, catalase, and acid phosphatase) in a contaminated sandy loam paddy soil. Three rates (0, 1, and 5%) and two mesh sizes (<0.25 and <1 mm) of biochar applications were investigated. After incubation, the physicochemical properties, extractable heavy metals, available phosphorus, and enzyme activity of soil samples were analyzed. The results demonstrated that rice straw biochar significantly (P < 0.05) increased the pH, electrical conductivity, and cation exchange capacity of the soil, especially at the 5% application rate. Both bamboo and rice straw biochar significantly (P < 0.05) decreased the concentration of CaCl2-extractable heavy metals as biochar application rate increased. The heavy metal extractability was significantly (P < 0.01) correlated with pH, water-soluble organic carbon, and available phosphorus in soil. The 5% application rate of fine rice straw biochar resulted in the greatest reductions of extractable Cu and Zn, 97.3 and 62.2%, respectively. Both bamboo and rice straw biochar were more effective at decreasing extractable Cu and Pb than removing extractable Cd and Zn from the soil. Urease activity increased by 143 and 107% after the addition of 5% coarse and fine rice straw biochars, respectively. Both bamboo and rice straw biochars significantly (P < 0.05) increased catalase

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

    PubMed

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

    2016-01-01

    Biochar is a carbon-rich solid material derived from the pyrolysis of agricultural and forest residual biomass. Previous studies have shown that biochar is suitable as an adsorbent for soil contaminants such as heavy metals and consequently reduces their bioavailability. However, the long-term effect of different biochars on metal extractability or soil health has not been assessed. Therefore, a 1-year incubation experiment was carried out to investigate the effect of biochar produced from bamboo and rice straw (at temperatures ≥500 °C) on the heavy metal (cadmium (Cd), copper (Cu), lead (Pb), and zinc (Zn)) extractability and enzyme activity (urease, catalase, and acid phosphatase) in a contaminated sandy loam paddy soil. Three rates (0, 1, and 5%) and two mesh sizes (<0.25 and <1 mm) of biochar applications were investigated. After incubation, the physicochemical properties, extractable heavy metals, available phosphorus, and enzyme activity of soil samples were analyzed. The results demonstrated that rice straw biochar significantly (P < 0.05) increased the pH, electrical conductivity, and cation exchange capacity of the soil, especially at the 5% application rate. Both bamboo and rice straw biochar significantly (P < 0.05) decreased the concentration of CaCl2-extractable heavy metals as biochar application rate increased. The heavy metal extractability was significantly (P < 0.01) correlated with pH, water-soluble organic carbon, and available phosphorus in soil. The 5% application rate of fine rice straw biochar resulted in the greatest reductions of extractable Cu and Zn, 97.3 and 62.2%, respectively. Both bamboo and rice straw biochar were more effective at decreasing extractable Cu and Pb than removing extractable Cd and Zn from the soil. Urease activity increased by 143 and 107% after the addition of 5% coarse and fine rice straw biochars, respectively. Both bamboo and rice straw biochars significantly (P < 0.05) increased catalase

  17. Distribution of Cd, Pb, Zn and Cu and their chemical speciations in soils from a peri-smelter area in northeast China

    NASA Astrophysics Data System (ADS)

    Du, Ping; Xue, Nandong; Liu, Li; Li, Fasheng

    2008-07-01

    An exploratory study on soil contamination of heavy metals was carried out surrounding Huludao zinc smelter in Liaoning province, China. The distribution of total heavy metals and their chemical speciations were investigated. The correlations between heavy metal speciations and soil pH values in corresponding sites were also analyzed. In general, Cd, Zn, Pb, Cu and As presented a significant contamination in the area near the smelter, comparied with Environmental Quality Standards for Soils in China. The geoaccumulation index showed the degree of contamination: Cd > Zn > Pb > Cu > As. There was no obvious pollution of Cr and Ni in the studied area. The speciation analysis showed that the dominant fraction of Cd and Zn was the acid soluble fraction, and the second was the residual fraction. Pb was mostly associated with the residual fraction, which constituted more than 50% of total concentration in all samples. Cu in residual fraction accounted for a high percentage (40-80%) of total concentration, and the proportion of Cu in the oxidizable fraction is higher than that of other metals. The distribution pattern of Pb and Zn was obviously affected by soil pH. It seemed that Pb and Zn content in acid solution fraction increased with increasing soil pH values, while Cd content in acid soluble fraction accounted for more proportion in neutral and alkaline groups than acidic one. The fraction distribution patterns of Cu in three pH groups were very similar and independent of soil pH values. And the residual fraction of Cu took a predominant part (50%) of the total content.

  18. Health risk of Hg, Pb, Cd, Zn, and Cu to the inhabitants around Huludao Zinc Plant in China via consumption of vegetables.

    PubMed

    Zheng, Na; Wang, Qichao; Zheng, Dongmei

    2007-09-20

    Huludao Zinc Plant in Huludao City, China is the largest zinc smelting plant in Asia. Heavy metals have contaminated its neighboring environment seriously. We collected 20 vegetables and the corresponding soil samples from eight sampling plots near Huludao Zinc Plant to investigate health risk of Hg, Pb, Cd, Zn, and Cu to the inhabitants around Huludao Zinc Plant in China via consumption of vegetables. Transfer factor (TF) values of Hg, Pb, Cd, Zn, and Cu from soil to vegetable and the target hazard quotients (THQs) to the possible health risks to local population through the food chain transfer were calculated accordingly. TF values of heavy metals from soil to vegetable decrease in the order of Cd>Zn>Cu>Pb>Hg. These TF values of leaves are higher than other tissues. Daily intakes of Hg, Pb, Cd, Zn, and Cu through the consumption of vegetables are 1.322, 574.3, 301.4, 5263, and 292.5 microg, respectively, for adults, and 1.029, 446.8, 234.5, 4095, and 227.6 microg, respectively, for children around Huludao Zinc Plant. This would lead to potential health risk, especially for children, since Cd or Pb individual THQ is high than 1. The total metal THQs (TTHQs) due to consumption of vegetables for adult and child are 5.79-9.90, 7.6-13.0, respectively. Comparing TTHQs in the sampling plots of different distances to Huludao Zinc Plant, it indicate that the health risks to inhabitants close to Huludao Zinc Plant (<500 m) is the highest, and at >1000 m distance is relatively higher than in 500-1000 m distance. However, the inhabitants who lived in 500-1000 m distance to Huludao Zinc Plant is also experiencing the adverse health risk due to TTHQ being higher than 1.

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

    PubMed

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

    2015-01-01

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

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

    PubMed Central

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

    2010-01-01

    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. PMID:21139877

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

    NASA Astrophysics Data System (ADS)

    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.

  2. Modeling removal of Cd, Cu, Pb, and Zn in acidic groundwater during neutralization by ambient surface waters and groundwaters

    USGS Publications Warehouse

    Paulson, A.J.; Balistrieri, L.

    1999-01-01

    Removal of Pb, Cu, Zn, and Cd during neutralization of acid rock drainage is examined using model simulations of field conditions and laboratory experiments involving mixing of natural drainage and surface waters or groundwaters. The simulations consider sorption onto hydrous Fe and Al oxides and particulate organic carbon, mineral precipitation, and organic and inorganic solution complexation of metals for two physical systems where newly formed oxides and particulate organic matter are either transported or retained along the chemical pathway. The calculations indicate that metal removal is a strong function of the physical system. Relative to direct discharge of ARD into streams, lower metal removals are observed where ARD enters streamwaters during the latter stages of neutralization by ambient groundwater after most of the Fe has precipitated and been retained in the soils. The mixing experiments, which represent the field simulations, also demonstrated the importance of dissolved metal to particle Fe ratios in controlling dissolved metal removal along the chemical pathway. Finally, model calculations indicate that hydrous Fe oxides and particulate organic carbon are more important than hydrous Al oxides in removing metals and that both inorganic and organic complexation must be considered when modeling metal removal from aquatic systems that are impacted by sulfide oxidation.Removal of Pb, Cu, Zn, and Cd during neutralization of acid rock drainage is examined using model simulations of field conditions and laboratory experiments involving mixing of natural drainage and surface waters or groundwaters. The simulations consider sorption onto hydrous Fe and Al oxides and particulate organic carbon, mineral precipitation, and organic and inorganic solution complexation of metals for two physical systems where newly formed oxides and particulate organic matter are either transported or retained along the chemical pathway. The calculations indicate that metal

  3. The two-phase leaching of Pb, Zn and Cd contaminated soil using EDTA and electrochemical treatment of the washing solution.

    PubMed

    Finzgar, Neza; Lestan, Domen

    2008-11-01

    The feasibility of a novel two-phase method for remediation of Pb (1374 mg kg(-1)), Zn (1007 mg kg(-1)), and Cd (9.1 mg kg(-1)) contaminated soil was evaluated. In the first phase we used EDTA for leaching heavy metals from the soil. In the second phase we used an electrochemical advanced oxidation process (EAOP) for the treatment and reuse of washing solution for soil rinsing (removal of the soil-retained, chelant-mobilized metallic species). In EAOP, a boron-doped diamond anode was used for the generation of hydroxyl radicals and oxidative decomposition of EDTA-metal complexes at a constant current density (15 mA cm(-2)). The released metals were removed from the solution by filtration as insoluble participate and by electro-deposition on the cathode. Four consecutive additions of 5.0 mm ol kg(-1) EDTA (total 20 mmol kg(-1)) removed 44% Pb, 14% Zn and 35% Cd from the soil. The mobility of the Pb, Zn and Cd (Toxicity Characteristic Leaching Procedure) left in the soil after remediation was reduced by 1.6, 3.4 and 1.5 times, respectively. The Pb oral availability (Physiologically Based Extraction Test) in the simulated stomach phase was reduced by 2.4 and in the intestinal phase by 1.7 times. The discharge solution was clear, almost colorless, with pH 7.73 and 0.47 mg L(-1) Pb, 1.03 mg L(-1) Zn, bellow the limits of quantification of Cd and 0.023 mM EDTA. The novel method enables soil leaching with small water requirements and no wastewater generation or other emissions into the environment. PMID:18762318

  4. 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.

    PubMed

    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.

  5. 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.

    PubMed

    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. PMID:26070738

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

    PubMed

    Yang, Silin; Zhou, Dequn; Yu, Huayong; Wei, Rong; Pan, Bo

    2013-06-01

    The distribution and chemical speciation of typical metals (Cu, Zn, Cd and Pb) in agricultural and non-agricultural soils were investigated in the area of Nanpan River, upstream of the Pearl River. The investigated four metals showed higher concentrations in agricultural soils than in non-agricultural soils, and the site located in factory district contained metals much higher than the other sampling sites. These observations suggested that human activities, such as water irrigation, fertilizer and pesticide applications might have a major impact on the distribution of metals. Metal speciation analysis presented that Cu, Zn and Cd were dominated by the residual fraction, while Pb was dominated by the reducible fraction. Because of the low mobility of the metals in the investigated area, no remarkable difference could be observed between upstream and downstream separated by the factory site. PMID:23466733

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

    PubMed

    Yang, Silin; Zhou, Dequn; Yu, Huayong; Wei, Rong; Pan, Bo

    2013-06-01

    The distribution and chemical speciation of typical metals (Cu, Zn, Cd and Pb) in agricultural and non-agricultural soils were investigated in the area of Nanpan River, upstream of the Pearl River. The investigated four metals showed higher concentrations in agricultural soils than in non-agricultural soils, and the site located in factory district contained metals much higher than the other sampling sites. These observations suggested that human activities, such as water irrigation, fertilizer and pesticide applications might have a major impact on the distribution of metals. Metal speciation analysis presented that Cu, Zn and Cd were dominated by the residual fraction, while Pb was dominated by the reducible fraction. Because of the low mobility of the metals in the investigated area, no remarkable difference could be observed between upstream and downstream separated by the factory site.

  8. Optimization of Ultrasound-Assisted Extraction of Cr, Cu, Zn, Cd, and Pb from Sediment, Followed by FAAS and GFAAS Analysis.

    PubMed

    Mimura, Aparecida M S; Oliveira, Marcone A L; Ciminelli, Virginia S T; Silva, Julio C J

    2016-01-01

    An ultrasound method for simultaneous extraction of Cr, Cu, Zn, Cd, and Pb from sediment, and determination by flame atomic absorption spectrometry (FAAS) and graphite furnace atomic absorption spectrometry (GFAAS) was proposed. The experimental results obtained using analytical curves and the method of standard additions agreed at a confidence level of 95% for all the analytes, as determined by FAAS and GFAAS, indicating no significant matrix effects. Recoveries ranged from 80.1 to 93.7% (certified reference material) and from 89 to 107% (spike tests). The LOD and LOQ results from the method were consistent with the techniques used (FAAS and GFAAS), with high analytical throughput. The proposed method was then used to determine Cr, Cu, Zn, Cd, and Pb in river sediment samples from Rio Doce, Minas Gerais, Brazil. The results indicated levels below those permitted by Brazilian legislation for all the analytes, with the exception of Cr. PMID:26851077

  9. Behavior of Zn2+, Cd2+, Ba2+ and Pb2+ cations in ferromanganese crusts from the Marcus Wake seamount (Pacific Ocean) in aqueous solutions of metal salts

    NASA Astrophysics Data System (ADS)

    Novikov, G. V.; Bogdanova, O. Yu.; Melnikov, M. E.; Lobus, N. V.; Drozdova, A. N.; Shulga, N. A.

    2016-01-01

    The behavior of heavy-metal cations in ore minerals of cobalt-rich ferromanganese crusts from the Marcus Wake seamount in aqueous solutions of metal salts was studied in experiments. The Zn2+ and Cd2+ cations showed high reactivity and Ba2+ and Pb2+ showed low reactivity. It was found that Zn2+ and Cd2+ cations within the ore mineral composition are mainly absorbed (up to 66%) whereas Pb2+ and Ba2+ are chemically bound (up to 70%). Ore minerals in the crusts are characterized by sorption properties and high ionexchange capacity by these cations (1.94-2.62 mg-equiv/g). The capacity values by heavy-metal cations for ore minerals of the crusts from different areas of the Marcus Wake seamount are close to each other.

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

    PubMed

    Niu, Li-Qin; Jia, Pu; Li, Shao-Peng; Kuang, Jia-Liang; He, Xiao-Xin; Zhou, Wen-Hua; Liao, Bin; Shu, Wen-Sheng; Li, Jin-Tian

    2015-10-01

    Heavy metal contamination of agricultural soils is of worldwide concern. Unfortunately, there are currently no efficient and sustainable approaches for addressing this concern. In this study, we conducted a field experiment in which an agricultural soil highly contaminated by cadmium (Cd), lead (Pb) and zinc (Zn) was treated on-site by an ancient agricultural technique, 'slash-and-char', that was able to convert the biomass feedstock (rice straw) into biochar in only one day. We found evidence that in comparison to the untreated soil, the treated soil was associated with decreased bioavailability of the heavy metals and increased vegetable yields. Most importantly, the treatment was also coupled with dramatic reductions in concentrations of the heavy metals in vegetables, which made it possible to produce safe crops in this highly contaminated soil. Collectively, our results support the idea that slash-and-char offers new promise for management of soils contaminated by Cd, Pb and Zn.

  11. Simultaneous determination of Cu 2+, Zn 2+, Cd 2+, Hg 2+ and Pb 2+ by using second-derivative spectrophotometry method

    NASA Astrophysics Data System (ADS)

    Han, Yanyan; Li, Yan; Si, Wei; Wei, Dong; Yao, Zhenxing; Zheng, Xianpeng; Du, Bin; Wei, Qin

    2011-09-01

    A new method of simultaneous determination of Cu 2+, Zn 2+, Cd 2+, Hg 2+ and Pb 2+ is proposed here by using the second-derivative spectrophotometry method. In pH = 10.35 Borax-NaOH buffer, using meso-tetra (3-methoxyl-4-hydroxylphenyl) porphyrin ([T-(3-MO-4-HP)P]) as chromomeric reagent, micelle solution was formed after Tween-80 surfactant was added into the solution containing Cu 2+, Zn 2+, Cd 2+, Hg 2+ and Pb 2+ ions. The original absorption spectrum of the above complexes was obtained after heating in the boiling water for 25 min. The second-derivative absorption peaks of five metal-porphyrin complexes can be separated from the original absorption spectrum by using chemometric tool. In this way, Cu 2+, Zn 2+, Cd 2+, Hg 2+ and Pb 2+ ions can be determined simultaneously. Under the optimal conditions, the linear ranges of the calibration curve were 0-0.60, 0-0.60, 0-0.40, 0-0.80 and 0-0.48 μg mL -1 for Cu 2+, Zn 2+, Cd 2+, Hg 2+ and Pb 2+, respectively. The molar absorptivity of these color systems were 1.38 × 10 5, 1.01 × 10 5, 3.24 × 10 5, 1.07 × 10 5 and 1.29 × 10 5 L mol -1 cm -1. The method developed in this paper has advantages in selectivity, sensitivity, operation and can effectively resolve spectra overlapping problem. This method has been applied to determine the real samples with satisfactory results.

  12. Accumulation of Cr, Pb, Cu, Ni, Zn and Cd in soil following irrigation with treated urban effluent in Australia.

    PubMed

    Smith, C J; Hopmans, P; Cook, F J

    1996-01-01

    The effect of irrigation with secondary treated municipal effluent on the accumulation of heavy metals (Cd, Cr, Cu, Ni, Pb, and Zn) was investigated by monitoring sites that had been irrigated with effluent for 4 and 17 years. At Wodonga, seven tree species were sprinkler irrigated with effluent at an average application rate of 1347 mm per annum from 1980 to 1984. The other site at Canberra was a large grass playing field (9 ha), half of which had been effluent irrigated since 1977. The non-effluent irrigated area served as the control area and provided reference 'background' concentration to assess the extent of contamination due to 17 years of effluent irrigation. Archived soil samples collected before the commencement of effluent irrigation were compared with those taken in 1984 at Wodonga to assess the extent of contamination. The concentration of labile metals was determined by extraction with EDTA because this method provides a quantitative measure of bioavailable metals. Irrigation with effluent did not increase the EDTA-extractable metals concentration at either site. Furthermore, the EDTA-extractable metal values were within the natural 'back-ground' range reported for Australian soils. These data suggest that it may take between 50 and 100 years for heavy metal levels (mainly Cd) in effluent-irrigated soil to reach the currently proposed threshold values for environmental concern. The potentially harmful effects of long-term accumulation of heavy metals on plant growth cannot be ignored and could affect the sustainability of land-based disposal of effluent. PMID:15093492

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

    PubMed

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

    2015-05-01

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

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

    PubMed

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

    2015-05-01

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

  15. Predicting the solubility and lability of Zn, Cd, and Pb in soils from a minespoil-contaminated catchment by stable isotopic exchange

    NASA Astrophysics Data System (ADS)

    Marzouk, E. R.; Chenery, S. R.; Young, S. D.

    2013-12-01

    The Rookhope catchment of Weardale, England, has a diverse legacy of contaminated soils due to extensive lead mining activity over four centuries. We measured the isotopically exchangeable content of Pb, Cd and Zn (E-values) in a large representative subset of the catchment soils (n = 246) using stable isotope dilution. All three metals displayed a wide range of %E-values (c. 1-100%) but relative lability followed the sequence Cd > Pb > Zn. A refinement of the stable isotope dilution approach also enabled detection of non-reactive metal contained within suspended sub-micron (<0.22 μm) colloidal particles (SCP-metal). For most soils, the presence of non-labile SCP-metal caused only minor over-estimation of E-values (<2%) but the effect was greater for soils with particularly large humus or carbonate contents. Approximately 80%, 53% and 66% of the variability in Zn, Cd and Pb %E-values (respectively) could be explained by pH, loss on ignition and total metal content. E-values were affected by the presence of ore minerals at high metal contents leading to an inconsistent trend in the relationship between %E-value and soil metal concentration. Metal solubility, in the soil suspensions used to measure E-values, was predicted using the WHAM geochemical speciation model (versions VI and VII). The use of total and isotopically exchangeable metal as alternative input variables was compared; the latter provided significantly better predictions of solubility, especially in the case of Zn. Lead solubility was less well predicted by either version of WHAM, with over-prediction at low pH and under-prediction at high soil pH values. Quantify the isotopically exchangeable fractions of Zn, Cd and Pb (E-values), and assess their local and regional variability, using multi-element stable isotope dilution, in a diverse range of soil ecosystems within the catchment of an old Pb/Zn mining area. Assess the controlling influences of soil properties on metal lability and develop

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

    NASA Astrophysics Data System (ADS)

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

    2016-06-01

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

  17. Removal Efficiency of the Heavy Metals Zn(II), Pb(II) and Cd(II) by Saprolegnia delica and Trichoderma viride at Different pH Values and Temperature Degrees.

    PubMed

    Ali, Esam H; Hashem, Mohamed

    2007-09-01

    The removal efficiency of the heavy metals Zn, Pb and Cd by the zoosporic fungal species Saprolegnia delica and the terrestrial fungus Trichoderma viride, isolated from polluted water drainages in the Delta of Nile in Egypt, as affected by various ranges of pH values and different temperature degrees,was extensively investigated. The maximum removal efficiency of S. delica for Zn(II) and Cd(II) was obtained at pH 8 and for Pb(II) was at pH 6 whilst the removal efficiency of T. viride was found to be optimum at pH 6 for the three applied heavy metals. Regardless the median lethal doses of the three heavy metals, Zn recorded the highest bioaccumulation potency by S. delica at all pH values except at pH 4, followed by Pb whereas Cd showed the lowest removal potency by the fungal species and vice versa in case of T. viride. The optimum biomass dry weight production by S. delica was found when the fungus was grown in the medium treated with the heavy metal Pb at pH 6, followed by Zn at pH 8 and Cd at pH 8. The optimum biomass dry weight yield by T. viride amended with Zn,Pb and Cd was obtained at pH 6 for the three heavy metals with the maximum value at Zn. The highest yield of biomass dry weight was found when T. viride treated with Cd at all different pH values followed by Pb whilst Zn output was the lowest and this result was reversed in case of S. delica. The maximum removal efficiency and the biomass dry weight production for the three tested heavy metals was obtained at the incubation temperature 20℃ in case of S. delica while it was 25℃ for T. viride. Incubation of T. viride at higher temperatures (30℃ and 35℃) enhanced the removal efficiency of Pb and Cd than low temperatures (15℃ and 20℃) and vice versa in case of Zn removal. At all tested incubation temperatures, the maximum yield of biomass dry weight was attained at Zn treatment by the two tested fungal species. The bioaccumulation potency of S. delica for Zn was higher than that for Pb at all

  18. Removal Efficiency of the Heavy Metals Zn(II), Pb(II) and Cd(II) by Saprolegnia delica and Trichoderma viride at Different pH Values and Temperature Degrees

    PubMed Central

    Hashem, Mohamed

    2007-01-01

    The removal efficiency of the heavy metals Zn, Pb and Cd by the zoosporic fungal species Saprolegnia delica and the terrestrial fungus Trichoderma viride, isolated from polluted water drainages in the Delta of Nile in Egypt, as affected by various ranges of pH values and different temperature degrees,was extensively investigated. The maximum removal efficiency of S. delica for Zn(II) and Cd(II) was obtained at pH 8 and for Pb(II) was at pH 6 whilst the removal efficiency of T. viride was found to be optimum at pH 6 for the three applied heavy metals. Regardless the median lethal doses of the three heavy metals, Zn recorded the highest bioaccumulation potency by S. delica at all pH values except at pH 4, followed by Pb whereas Cd showed the lowest removal potency by the fungal species and vice versa in case of T. viride. The optimum biomass dry weight production by S. delica was found when the fungus was grown in the medium treated with the heavy metal Pb at pH 6, followed by Zn at pH 8 and Cd at pH 8. The optimum biomass dry weight yield by T. viride amended with Zn,Pb and Cd was obtained at pH 6 for the three heavy metals with the maximum value at Zn. The highest yield of biomass dry weight was found when T. viride treated with Cd at all different pH values followed by Pb whilst Zn output was the lowest and this result was reversed in case of S. delica. The maximum removal efficiency and the biomass dry weight production for the three tested heavy metals was obtained at the incubation temperature 20℃ in case of S. delica while it was 25℃ for T. viride. Incubation of T. viride at higher temperatures (30℃ and 35℃) enhanced the removal efficiency of Pb and Cd than low temperatures (15℃ and 20℃) and vice versa in case of Zn removal. At all tested incubation temperatures, the maximum yield of biomass dry weight was attained at Zn treatment by the two tested fungal species. The bioaccumulation potency of S. delica for Zn was higher than that for Pb at all

  19. 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.

    PubMed

    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.

  20. 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.

    PubMed

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

    2016-02-01

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

  1. 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

    NASA Astrophysics Data System (ADS)

    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.

  2. Phytoremediation of Cd, Cr, Cu, Mn, Fe, Ni, Pb and Zn from aqueous solution using Phragmites cummunis, Typha angustifolia and Cyperus esculentus.

    PubMed

    Chandra, Ram; Yadav, Sangeeta

    2011-07-01

    A comparative bioaccumulation pattern and ultra structural changes were studied in Phragmites cummunis, Typha angustifolia and Cyperus esculentus in mixed metals solution of cadmium (Cd), chromium (Cr), copper (Cu), iron (Fe), manganese (Mn), nickel (Ni), lead (Pb) and zinc (Zn). P. cummunis was observed to be a shoot accumulator for Cr, Fe, Mn, Ni, Pb, and Zn. However, T. angustifolia was found to be a root accumulator for Cd, Cr, Cu, Fe, Ni and Pb. In addition, C. esculentus also accumulated most of the tested heavy metals in the roots, while Mn and Fe were translocated up to leaves. Further, the long term metal treatment showed maximum accumulation of all heavy metals in P. cummunis followed by T. angustifolia and C. esculentus. Among heavy metals, Fe was accumulated maximum, i.e., >1000 microg g(-1) by all three plants. Simultaneously, the adverse effects on biochemical parameters were noted earlier in C. esculentus than T. angustifolia and P. cummunis. Ultra structural observation showed the cellular changes in wetland plants after longer exposure. Results revealed that P. cummunis and T. angustifolia had more potential for tested metals than C. esculentus. This study established that these wetland plants could be used for heavy metals phytoremediation from metal containing industrial wastewater. PMID:21972504

  3. Predicting As, Cd, Cu, Pb and Zn levels in grasses (Agrostis sp. and Poa sp.) and stinging nettle (Urtica dioica) applying soil-plant transfer models.

    PubMed

    Boshoff, Magdalena; De Jonge, Maarten; Scheifler, Renaud; Bervoets, Lieven

    2014-09-15

    The aim of this study was to derive regression-based soil-plant models to predict and compare metal(loid) (i.e. As, Cd, Cu, Pb and Zn) concentrations in plants (grass Agrostis sp./Poa sp. and nettle Urtica dioica L.) among sites with a wide range of metal pollution and a wide variation in soil properties. Regression models were based on the pseudo total (aqua-regia) and exchangeable (0.01 M CaCl2) soil metal concentrations. Plant metal concentrations were best explained by the pseudo total soil metal concentrations in combination with soil properties. The most important soil property that influenced U. dioica metal concentrations was the clay content, while for grass organic matter (OM) and pH affected the As (OM) and Cu and Zn (pH). In this study multiple linear regression models proved functional in predicting metal accumulation in plants on a regional scale. With the proposed models based on the pseudo total metal concentration, the percentage of variation explained for the metals As, Cd, Cu, Pb and Zn were 0.56%, 0.47%, 0.59%, 0.61%, 0.30% in nettle and 0.46%, 0.38%, 0.27%, 0.50%, 0.28% in grass. PMID:25000582

  4. Predicting As, Cd, Cu, Pb and Zn levels in grasses (Agrostis sp. and Poa sp.) and stinging nettle (Urtica dioica) applying soil-plant transfer models.

    PubMed

    Boshoff, Magdalena; De Jonge, Maarten; Scheifler, Renaud; Bervoets, Lieven

    2014-09-15

    The aim of this study was to derive regression-based soil-plant models to predict and compare metal(loid) (i.e. As, Cd, Cu, Pb and Zn) concentrations in plants (grass Agrostis sp./Poa sp. and nettle Urtica dioica L.) among sites with a wide range of metal pollution and a wide variation in soil properties. Regression models were based on the pseudo total (aqua-regia) and exchangeable (0.01 M CaCl2) soil metal concentrations. Plant metal concentrations were best explained by the pseudo total soil metal concentrations in combination with soil properties. The most important soil property that influenced U. dioica metal concentrations was the clay content, while for grass organic matter (OM) and pH affected the As (OM) and Cu and Zn (pH). In this study multiple linear regression models proved functional in predicting metal accumulation in plants on a regional scale. With the proposed models based on the pseudo total metal concentration, the percentage of variation explained for the metals As, Cd, Cu, Pb and Zn were 0.56%, 0.47%, 0.59%, 0.61%, 0.30% in nettle and 0.46%, 0.38%, 0.27%, 0.50%, 0.28% in grass.

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

    PubMed

    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.

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

    PubMed

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

    2016-07-01

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

  7. Concentrations of Mn, Fe, Cu, Zn, Cr, Cd, Pb, Ni in selected Nigerian tubers, legumes and cereals and estimates of the adult daily intakes.

    PubMed

    Akinyele, I O; Shokunbi, O S

    2015-04-15

    This study was designed to determine the levels of microminerals (manganese (Mn), iron (Fe), copper (Cu), zinc (Zn), chromium (Cr)) and heavy metals (cadmium (Cd), lead (Pb) and nickel (Ni)) in some tubers, legumes and cereals obtained from the markets in Abeokuta city, South-West Nigeria. The food samples were digested by dry ashing procedure and their minerals were determined by atomic absorption spectrophotometer. The results show mean values of 1.67-32.00, 7.25-61.58, 1.59-10.56, 6.65-46.99, 0.02-0.58, <0.01-0.09, <0.08, and 0.06-0.14 mg/kg for Mn, Fe, Cu, Zn, Cr, Cd, Pb and Ni respectively. The levels of these metals in all the samples analysed were within the ranges reported for similar tubers, legumes and cereals from various parts of the world. The daily intakes of the metals through tubers, legumes and cereals were found to be lower than the provisional tolerable daily intakes proposed by Joint FAO/WHO Expert Committee on Food Additives.

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

    PubMed Central

    Konuma, Susumu; Nakamura, Yoshiyuki

    2016-01-01

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

  9. pH-dependent toxicity of Cd, Cu, Ni, Pb and Zn to Ceriodaphnia dubia, Pimephales promelas, Hyalella azteca and Lumbriculus variegatus

    SciTech Connect

    Schubauer-Berigan, M.K.; Dierkes, J.R.; Monson, P.D. ); Ankley, G.T. . Environmental Protection Agency)

    1993-07-01

    The speciation and bioavailability of metals are known to be affected by pH. Although many studies have focused on effects on metals of pH changes resulting from lake acidification, metal toxicity changes at higher pH values are of great interest to those performing effluent and sediment toxicity testing and toxicity identification evaluations (TIEs). In addition, most previous studies have addressed metal toxicity changes with pH to water-column organisms rather than to benthic or epibenthic species. The authors tested the acute toxicity of five metals (Cd, Cu, Ni, Pb, and Zn) to Ceriodaphnia dubia, Pimephales promelas, Hyalella azteca, and Lubriculus variegatus at three pH values in very hard reconstituted water. Toxicity of Cd, Ni, and zn was greatest at pH 8.3 and least at pH 6.3 to most of these species. Conversely, the toxicity of Cu and Pb was greatest at pH 6.3 and least at pH 8.3 to most of the species. The acute toxicity of most of the metals to Lumbriculus variegatus was very low and occasionally was above the aqueous solubility of the metal salts in the reconstituted water.

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

    PubMed

    Hosokawa, Shinya; Konuma, Susumu; Nakamura, Yoshiyuki

    2016-01-01

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

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

    PubMed

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

    2016-06-01

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

  12. 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.

    PubMed

    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.

  13. 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.

    PubMed

    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. PMID:24062066

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

    NASA Astrophysics Data System (ADS)

    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.

  15. Flowing Liquid Anode Atmospheric Pressure Glow Discharge as an Excitation Source for Optical Emission Spectrometry with the Improved Detectability of Ag, Cd, Hg, Pb, Tl, and Zn.

    PubMed

    Greda, Krzysztof; Swiderski, Krzysztof; Jamroz, Piotr; Pohl, Pawel

    2016-09-01

    A novel atmospheric pressure glow discharge generated in contact with a flowing liquid anode (FLA-APGD) was developed as the efficient excitation source for the optical emission spectrometry (OES) detection. Differences in the appearance and the electrical characteristic of the FLA-APGD and a conventional system operated with a flowing liquid cathode (FLC-APGD) were studied in detail and discussed. Under the optimal operating conditions for the FLA-APGD, the emission from the analytes (Ag, Cd, Hg, Pb, Tl, and Zn) was from 20 to 120 times higher as compared to the FLC-APGD. Limits of detections (LODs) established with a novel FLA-APGD system were on average 20 times better than those obtained for the FLC-APGD. A further improvement of the LODs was achieved by reducing the background shift interferences and, as a result, the LODs for Ag, Cd, Hg, Pb, Tl, and Zn were 0.004, 0.040, 0.70, 1.7, 0.035, and 0.45 μg L(-1), respectively. The precision of the FLA-APGD-OES method was evaluated to be within 2-5% (as the relative standard deviation of the repeated measurements). The method found its application in the determination of the content of Ag, Cd, Hg, Pb, Tl, and Zn in a certified reference material (CRM) of Lobster hepatopancreas (TORT-2), four brass samples as well as mineral water and tea leaves samples spiked with the analytes. In the case of brass samples, a reference method, i.e., inductively coupled plasma optical emission spectrometry (ICP-OES) was used. A good agreement between the results obtained with FLA-APGD-OES and the certified values for the CRM TORT-2 as well as the reference values obtained with ICP-OES for the brass samples was revealed, indicating the good accuracy of the proposed method. The recoveries obtained for the spiked samples of mineral water and tea leaves were within the range of 97.5-102%. PMID:27476678

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

    PubMed

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

    2014-09-19

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

  17. Heavy metal (As, Cd, Hg, Pb, Cu, Zn, Se) concentrations in muscle and bone of four commercial fish caught in the central Adriatic Sea, Italy.

    PubMed

    Perugini, Monia; Visciano, Pierina; Manera, Maurizio; Zaccaroni, Annalisa; Olivieri, Vincenzo; Amorena, Michele

    2014-04-01

    Heavy metal (As, Cd, Cu, Pb, Zn, Hg and Se) concentrations in the muscle and bone of four fish species (Mullus barbatus, Merluccius merluccius, Micromesistius poutassou, and Scomber scombrus) from the central Adriatic Sea were measured and the relationships between fish size (length and weight) and metal concentrations in the tissues were investigated. Samples were analyzed by inductively coupled plasma-atomic emission spectrophotometry with automatic dual viewing. In the muscle, results of linear regression analysis showed that, except for mercury, significant relationships between metal concentrations and fish size were negative. Only mercury levels were positively correlated with Atlantic mackerel size (p < 0.05). No significant variations of heavy metal concentrations were observed in muscles of the examined species, but a significant difference (p < 0.01) was found for As, Cd, Pb, and Se concentrations in bone. All the investigated metals showed higher values in the muscle than in bone, except for lead and zinc. Regarding cadmium, lead, and mercury maximum levels, set for the edible portion by European legislation, several samples exceeded these values, confirming the heavy metal presence in species caught near the Jabuka Pit.

  18. Heavy metal (As, Cd, Hg, Pb, Cu, Zn, Se) concentrations in muscle and bone of four commercial fish caught in the central Adriatic Sea, Italy.

    PubMed

    Perugini, Monia; Visciano, Pierina; Manera, Maurizio; Zaccaroni, Annalisa; Olivieri, Vincenzo; Amorena, Michele

    2014-04-01

    Heavy metal (As, Cd, Cu, Pb, Zn, Hg and Se) concentrations in the muscle and bone of four fish species (Mullus barbatus, Merluccius merluccius, Micromesistius poutassou, and Scomber scombrus) from the central Adriatic Sea were measured and the relationships between fish size (length and weight) and metal concentrations in the tissues were investigated. Samples were analyzed by inductively coupled plasma-atomic emission spectrophotometry with automatic dual viewing. In the muscle, results of linear regression analysis showed that, except for mercury, significant relationships between metal concentrations and fish size were negative. Only mercury levels were positively correlated with Atlantic mackerel size (p < 0.05). No significant variations of heavy metal concentrations were observed in muscles of the examined species, but a significant difference (p < 0.01) was found for As, Cd, Pb, and Se concentrations in bone. All the investigated metals showed higher values in the muscle than in bone, except for lead and zinc. Regarding cadmium, lead, and mercury maximum levels, set for the edible portion by European legislation, several samples exceeded these values, confirming the heavy metal presence in species caught near the Jabuka Pit. PMID:24242233

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

    PubMed Central

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

    2014-01-01

    We propose a series of icosahedral matryoshka clusters of A@B12@A20 (A = Sn, Pb; B = Mg, Zn, Cd), which possess large HOMO-LUMO gaps (1.29 to 1.54 eV) and low formation energies (0.06 to 0.21 eV/atom). A global minimum search using a genetic algorithm and density functional theory calculations confirms that such onion-like three-shell structures are the ground states for these A21B12 binary clusters. All of these icosahedral matryoshka clusters, including two previously found ones, i.e., [As@Ni12@As20]3− and [Sn@Cu12@Sn20]12−, follow the 108-electron rule, which originates from the high Ih symmetry and consequently the splitting of superatom orbitals of high angular momentum. More interestingly, two magnetic matryoshka clusters, i.e., Sn@Mn12@Sn20 and Pb@Mn12@Pb20, are designed, which combine a large magnetic moment of 28 µB, a moderate HOMO-LUMO gap, and weak inter-cluster interaction energy, making them ideal building blocks in novel magnetic materials and devices. PMID:25376938

  20. High-Temperature Vaporization Behavior of Oxides II. Oxides of Be, Mg, Ca, Sr, Ba, B, Al, Ga, In, Tl, Si, Ge, Sn, Pb, Zn, Cd, and Hg

    NASA Astrophysics Data System (ADS)

    Lamoreaux, R. H.; Hildenbrand, D. L.; Brewer, L.

    1987-07-01

    In order to assess the high-temperature vaporization behavior and equilibrium gas phase compositions over the condensed oxides of Be, Mg, Ca, Sr, Ba, B, Al, Ga, In, Tl, Si, Ge, Sn, Pb, Zn, Cd, and Hg, the relevant thermodynamic and molecular constant data have been compiled and critically evaluated. Selected values of the Gibbs energy functions of condensed and vapor phases are given in the form of equations valid over wide temperature ranges, along with the standard entropies and enthalpies of formation. These data were used to generate plots of equilibrium partial pressures of vapor species as functions of temperature for representative environmental conditions ranging from reducing to oxidizing. The calculated partial pressures and compositions agree, for the most part, with experimental results obtained under comparable conditions. Maximum vaporization rates have been calculated using the Hertz-Knudsen equation. Literature references are given.

  1. Mixture toxicity and tissue interactions of Cd, Cu, Pb and Zn in earthworms (Oligochaeta) in laboratory and field soils: a critical evaluation of data.

    PubMed

    Weltje, L

    1998-05-01

    Soil organisms inhabiting contaminated field sites are usually exposed to mixtures of toxicants. In such mixtures, toxicants can interact to express enhanced or weakened toxicity. Therefore, mixture effects should be considered in risk assessment methods for polluted soils. Data on mixture toxicity to soil organisms are scarce, however. In this paper, data on sublethal toxicity and tissue concentrations of Cd. Cu, Pb and Zn mixtures in earthworms are evaluated and compared with data on other organisms. Toxic effects were mainly antagonistic for total soil concentrations and nearly concentration-additive for 0.01 M CaCl2-extractable soil concentrations. Evidence to support concentration-additive behaviour of metals was found in interaction patterns within earthworm tissues. A method is proposed to assess the sublethal toxicity of metal mixtures in field soils to earthworms, based on single metal experiments from the laboratory. Finally, suggestions are made on how to incorporate mixture toxicity in risk assessment for polluted soils. PMID:9570111

  2. Removal of divalent heavy metals (Cd, Cu, Pb, and Zn) and arsenic(III) from aqueous solutions using scoria: kinetics and equilibria of sorption.

    PubMed

    Kwon, Jang-Soon; Yun, Seong-Taek; Lee, Jong-Hwa; Kim, Soon-Oh; Jo, Ho Young

    2010-02-15

    Kinetic and equilibrium sorption experiments were conducted on removal of divalent heavy metals (Pb(II), Cu(II), Zn(II), Cd(II)) and trivalent arsenic (As(III)) from aqueous solutions by scoria (a vesicular pyroclastic rock with basaltic composition) from Jeju Island, Korea, in order to examine its potential use as an efficient sorbent. The removal efficiencies of Pb, Cu, Zn, Cd, and As by the scoria (size=0.1-0.2mm, dose=60gL(-1)) were 94, 70, 63, 59, and 14%, respectively, after a reaction time of 24h under a sorbate concentration of 1mM and the solution pH of 5.0. A careful examination on ionic concentrations in sorption batches suggested that sorption behaviors of heavy metals onto scoria are mainly controlled by cation exchange. On the other hand, arsenic appeared to be sensitive to specific sorption onto hematite (a minor constituent of scoria). Equilibrium sorption tests indicated that the removal efficiency for heavy metals increases with increasing pH of aqueous solutions, which is resulted from precipitation as hydroxides. Similarly, multi-component systems containing heavy metals and arsenic showed that the arsenic removal increases with increasing pH of aqueous solutions, which can be attributed to coprecipitation with metal hydroxides. The empirically determined sorption kinetics were well fitted to a pseudo-second order model, while equilibrium sorption data for heavy metals and arsenic onto scoria were consistent with the Langmuir and Freundlich isotherms, respectively. Natural scoria studied in this work is an efficient sorbent for concurrent removal of divalent heavy metals and arsenic.

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

    PubMed

    Lindblom, E; Ahlman, S; Mikkelsen, P S

    2011-07-01

    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 parameters, which allowed using an open not specified uniform prior for the dry deposition parameter. We used an exponential likelihood function based on the sum of squared errors between observed and simulated event masses and adjusted a scaling factor to cover 95% of the observations within the empirical 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 of accumulated metal available on the conceptual catchment surface. Forward Monte Carlo analysis based on the posterior parameter sets covered 95% of the observed event mean concentrations, and 95% prediction quantiles for site mean concentrations were estimated to 470 μg/l ± 20% for Zn, 295 μg/l ± 40% for Cu, 20 μg/l ± 80% for Pb and 0.6 μg/l ± 35% for Cd. This uncertainty-based calibration procedure adequately describes the prediction uncertainty conditioned on the used model and data, but seasonal and site-to-site variation is not considered, i.e. predicting metal concentrations in stormwater runoff from gauged as well as ungauged catchments with the SEWSYS model is generally more uncertain than the indicated numbers.

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

    NASA Astrophysics Data System (ADS)

    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.

  5. Assessment of heavy metals/metalloid (As, Pb, Cd, Ni, Zn, Cr, Cu, Mn) concentrations in edible fish species tissue in the Pearl River Delta (PRD), China.

    PubMed

    Leung, H M; Leung, A O W; Wang, H S; Ma, K K; Liang, Y; Ho, K C; Cheung, K C; Tohidi, F; Yung, K K L

    2014-01-15

    The major aim of this study was to investigate heavy metal content of edible fish in the PRD. Eleven species of fish (consisting of 711 individuals) [catfish (Clarias fuscus), tilapia (Oreochromis mossambicus), grass carp (Ctenopharyngodon idellus), bighead carp (Aristichthys nobilis), mandarin fish (Siniperca kneri), snakehead (Channa asiatiea), black bass (Micropterus salmoides), mangrove snapper (Lutjanus griseus), star snapper (Lutjanu stellatus), snubnose pompano (Trachinotus blochii) and orange-spotted grouper (Epinephelus coioides)] were collected for the analyses of heavy metals. Overall concentrations (mg/kg, ww) in the fish muscles were: As (0.03-1.53), Pb (0.03-8.62), Cd (0.02-0.06), Ni (0.44-9.75), Zn (15.7-29.5), Cr (0.22-0.65), Cu (0.79-2.26), Mn (0.82-6.91). Significant level of Pb were found in tilapia at all locations. It is recommended that heavy metal concentrations in different fish species must be determined on a regular basis in the future so as to reduce human health risks from acute and chronic food intoxication. PMID:24239097

  6. Assessment of heavy metals/metalloid (As, Pb, Cd, Ni, Zn, Cr, Cu, Mn) concentrations in edible fish species tissue in the Pearl River Delta (PRD), China.

    PubMed

    Leung, H M; Leung, A O W; Wang, H S; Ma, K K; Liang, Y; Ho, K C; Cheung, K C; Tohidi, F; Yung, K K L

    2014-01-15

    The major aim of this study was to investigate heavy metal content of edible fish in the PRD. Eleven species of fish (consisting of 711 individuals) [catfish (Clarias fuscus), tilapia (Oreochromis mossambicus), grass carp (Ctenopharyngodon idellus), bighead carp (Aristichthys nobilis), mandarin fish (Siniperca kneri), snakehead (Channa asiatiea), black bass (Micropterus salmoides), mangrove snapper (Lutjanus griseus), star snapper (Lutjanu stellatus), snubnose pompano (Trachinotus blochii) and orange-spotted grouper (Epinephelus coioides)] were collected for the analyses of heavy metals. Overall concentrations (mg/kg, ww) in the fish muscles were: As (0.03-1.53), Pb (0.03-8.62), Cd (0.02-0.06), Ni (0.44-9.75), Zn (15.7-29.5), Cr (0.22-0.65), Cu (0.79-2.26), Mn (0.82-6.91). Significant level of Pb were found in tilapia at all locations. It is recommended that heavy metal concentrations in different fish species must be determined on a regular basis in the future so as to reduce human health risks from acute and chronic food intoxication.

  7. Influence of different mineral and Organic pesticide treatments on Cd(II), Cu(II), Pb(II), and Zn(II) contents determined by derivative potentiometric stripping analysis in Italian white and red wines.

    PubMed

    Salvo, Francesco; La Pera, Lara; Di Bella, Giuseppa; Nicotina, Mariano; Dugo, Giacomo

    2003-02-12

    This paper deals with the use of derivative potentiometric stripping analysis (dPSA) as a rapid and precise method to determine Cd(II), Cu(II), Pb(II), and Zn(II) levels in red and white wine samples from Sicily, Campania, and Tuscany and to investigate the possible connection between the content of these metals and the pesticide treatments used in vine-growing to control plant diseases and pests. dPSA allowed direct quantitation of heavy metals in acidified wines without any sample pretreatment. Mean recoveries of Cd(II), Cu(II), Pb(II), and Zn(II) ranged from 95.5 to 99.2% for white wine samples and from 96.1 to 100.0% for red wine samples. The obtained results showed that Cd(II) was not found in any sample and that Cu(II), Pb(II), and Zn(II) levels were always lower than the toxicity limits in both fungicide- and water-treated wines. Nevertheless, the contents of metals were increased in samples from organic and inorganic pesticides treatment with respect to the water-treated samples. In particular, quinoxyfen, dinocap-penconazole, and dinocap applications considerably increased Cu(II) and Zn(II) contents in white and red wines. The levels of lead were significantly raised by azoxystrobin and sulfur treatments.

  8. Geochemical position of Pb, Zn and Cd in soils near the Olkusz mine/smelter, South Poland: effects of land use, type of contamination and distance from pollution source.

    PubMed

    Chrastný, Vladislav; Vaněk, Aleš; Teper, Leslaw; Cabala, Jerzy; Procházka, Jan; Pechar, Libor; Drahota, Petr; Penížek, Vít; Komárek, Michael; Novák, Martin

    2012-04-01

    The soils adjacent to an area of historical mining, ore processing and smelting activities reflects the historical background and a mixing of recent contamination sources. The main anthropogenic sources of metals can be connected with historical and recent mine wastes, direct atmospheric deposition from mining and smelting processes and dust particles originating from open tailings ponds. Contaminated agriculture and forest soil samples with mining and smelting related pollutants were collected at different distances from the source of emission in the Pb-Zn-Ag mining area near Olkusz, Upper Silesia to (a) compare the chemical speciation of metals in agriculture and forest soils situated at the same distance from the point source of pollution (paired sampling design), (b) to evaluate the relationship between the distance from the polluter and the retention of the metals in the soil, (c) to describe mineralogy transformation of anthropogenic soil particles in the soils, and (d) to assess the effect of deposited fly ash vs. dumped mining/smelting waste on the mobility and bioavailability of metals in the soil. Forest soils are much more affected with smelting processes than agriculture soils. However, agriculture soils suffer from the downward metal migration more than the forest soils. The maximum concentrations of Pb, Zn, and Cd were detected in a forest soil profile near the smelter and reached about 25 g kg(- 1), 20 g kg(- 1) and 200 mg kg(- 1) for Pb, Zn and Cd, respectively. The metal pollutants from smelting processes are less stable under slightly alkaline soil pH then acidic due to the metal carbonates precipitation. Metal mobility ranges in the studied forest soils are as follows: Pb > ZnCd for relatively circum-neutral soil pH (near the smelter), Cd > Zn > Pb for acidic soils (further from the smelter). Under relatively comparable pH conditions, the main soil properties influencing metal migration are total organic carbon and cation exchange

  9. Influence of Ca/Mg ratio on phytoextraction properties of Salix viminalis I. The effectiveness of Cd, Cu, Pb, and Zn bioaccumulation and plant growth.

    PubMed

    Mleczek, Mirosław; Kozlowska, Monika; Kaczmarek, Zygmunt; Chadzinikolau, Tamara; Golinski, Piotr

    2012-01-01

    Phytoremediation and its efficiency--influenced by several factors-is prime concern in reduction of environment contamination with heavy metals. The aim of the study was to estimate in controlled conditions--in relation to the natural Ca/Mg ratio 4:1--the influence of different Ca/Mg ratios (1:1/4, 20:1, 1:10) on selected heavy metals (Cd, Cu, Pb, and Zn) accumulation efficiency shown by three morphological parts of Salix viminalis 'Cinamomea' (cane bark, shoots and roots). Accumulation of heavy metals in experimental conditions was significantly Ca/Mg ratio dependent, and occurred in the following order: 1:10 > 4:1 > 20:1 > 1:1/4. The highest accumulation under 0.5 mM solutions (as compared to 0.1 mM) was noted for copper and zinc, and the lowest for cadmium. Biometric parameters of Salix viminalis cuttings revealed the highest biomass productivity under 20:1 and 4:1 Ca/Mg ratios. In the case of shoot length increase, both metal concentration and kind of metal present in the solution were important. The results indicate that higher calcium ion concentration in solution (Ca/Mg 20:1) stimulates Salix viminalis growth by 3 fold when compared to other Ca/Mg ratio. It can be an important factor in remediation of the environment with this plant.

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

    PubMed

    Freitas, Olga M M; Martins, Ramiro J E; Delerue-Matos, Cristina M; Boaventura, Rui A R

    2008-05-01

    Specific marine macro algae species abundant at the Portuguese coast (Laminaria hyperborea, Bifurcaria bifurcata, Sargassum muticum and Fucus spiralis) were shown to be effective for removing toxic metals (Cd(II), Zn(II) and Pb(II)) from aqueous solutions. The initial metal concentrations in solution were about 75-100 mg L(-1). The observed biosorption capacities for cadmium, zinc and lead ions were in the ranges of 23.9-39.5, 18.6-32.0 and 32.3-50.4 mg g(-1), respectively. Kinetic studies revealed that the metal uptake rate was rather fast, with 75% of the total amount occurring in the first 10 min for all algal species. Experimental data were well fitted by a pseudo-second order rate equation. The contribution of internal diffusion mechanism was significant only to the initial biosorption stage. Results indicate that all the studied macro algae species can provide an efficient and cost-effective technology for eliminating heavy metals from industrial effluents. PMID:17935878

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

    PubMed Central

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

    2013-01-01

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

  12. Modelling removal mechanisms of Pb, Cu, Zn and Cd in acidic groundwater during the neutralization by ambient surface and ground waters

    USGS Publications Warehouse

    Paulson, Anthony J.; Balistrieri, Laurie S.

    1999-01-01

    Removal of Pb, Cu, Zn, and Cd during neutralization of acid rock drainage is examined using model simulations of field conditions and laboratory experiments involving mixing of natural drainage and surface waters or groundwaters. The simulations consider sorption onto hydrous Fe and Al oxides and particulate organic carbon, mineral precipitation, and organic and inorganic solution complexation of metals for two physical systems where newly formed oxides and particulate organic matter are either transported or retained along the chemical pathway. The calculations indicate that metal removal is a strong function of the physical system. Relative to direct discharge of ARD into streams, lower metal removals are observed where ARD enters streamwaters during the latter stages of neutralization by ambient groundwater after most of the Fe has precipitated and been retained in the soils. The mixing experiments, which represent the field simulations, also demonstrated the importance of dissolved metal to particle Fe ratios in controlling dissolved metal removal along the chemical pathway. Finally, model calculations indicate that hydrous Fe oxides and particulate organic carbon are more important than hydrous Al oxides in removing metals and that both inorganic and organic complexation must be considered when modeling metal removal from aquatic systems that are impacted by sulfide oxidation.

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

  14. Determination of Pb(II), Zn(II), Cd(II), and Co(II) ions by flame atomic absorption spectrometry in food and water samples after preconcentration by coprecipitation with Mo(VI)-diethyldithiocarbamate.

    PubMed

    Tufekci, Mehmet; Bulut, Volkan Numan; Elvan, Hamide; Ozdes, Duygu; Soylak, Mustafa; Duran, Celal

    2013-02-01

    A new, simple, and rapid separation and preconcentration procedure, for determination of Pb(II), Cd(II), Zn(II), and Co(II) ions in environmental real samples, has been developed. The method is based on the combination of coprecipitation of analyte ions by the aid of the Mo(VI)-diethyldithiocarbamate-(Mo(VI)-DDTC) precipitate and flame atomic absorption spectrometric determinations. The effects of experimental conditions like pH of the aqueous solution, amounts of DDTC and Mo(VI), standing time, centrifugation rate and time, sample volume, etc. and also the influences of some foreign ions were investigated in detail on the quantitative recoveries of the analyte ions. The preconcentration factors were found to be 150 for Pb(II), Zn(II) and Co(II), and 200 for Cd(II) ions. The detection limits were in the range of 0.1-2.2 μg L(-1) while the relative standard deviations were found to be lower than 5 % for the studied analyte ions. The accuracy of the method was checked by spiked/recovery tests and the analysis of certified reference material (CRM TMDW-500 Drinking Water). The procedure was successfully applied to seawater and stream water as liquid samples and baby food and dried eggplant as solid samples in order to determine the levels of Pb(II), Cd(II), Zn(II), and Co(II) ions. PMID:22527456

  15. 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.

    PubMed

    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 < 0.05) higher levels of As (1.38 μg g(-1) dw) and Cu (1.85 μg g(-1) dw) than yellowfin tuna Thunnus albacares, whereas Pb concentrations (0.18 μg g(-1) dw) were significantly (p < 0.05) higher in T. albacares. The sequence of elemental concentrations in both species was Zn > 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. PMID:22684512

  16. [Heavy metal contamination and Pb isotopic composition in natural soils around a Pb/Zn mining and smelting area].

    PubMed

    Sun, Rui; Shu, Fan; Hao, Wei; Li, Li; Sun, Wei-Ling

    2011-04-01

    The heavy metal (Pb, Zn, Cr, Cu, Cd, and Hg) concentrations in the A horizon and C horizon soils, collected around the Pb/Zn mining and smelting area of Shuikoushan in Hunan, China, were investigated, and the Pb isotopic compositions were also determined to identify the potential origin of Pb in the A horizon soil. Compared with C horizon soils, the A horizon soils exhibit elevated heavy metal concentrations, especially in the vicinity of the mining and smelting area. This reveals that the surface soil was contaminated to some degree. The contents of Pb, Zn, Cr, Cu, Cd, and Hg in soils are up to 3966.88, 2086.25, 135.31, 185.63, 56.15, and 16.434 mg/kg, respectively. The potential risks caused by different metals are in the order of Cd > Hg > Pb > Cu > Zn = Cr. Much higher potential ecological risk was observed for the central area (Shuikoushan Pb/Zn mining and smelting area) than for the surrounding area. About 34%, 33%, 11%, and 22% of the sampling sites demonstrate low, moderate, considerable, and very high potential ecological risk in the central area, while about 68%, 16%, 10%, and 6% of the sampling sites show low, moderate, considerable, and very high potential ecological risk in the surrounding area, respectively. Compared with the Pb isotopic compositions in the C horizon soils (206Pb/207Pb 1.168-1.246, 208 Pb/206 Pb 2.014-2.130), the Pb in the A horizon soils has lower 206 Pb/207Pb ratios (1.166-1.226) and higher 208Pb/206Pb ratios (2.043-2. 135). The Pb in the A horizon soils predominantly derives from two-component mixing resources. One is the parent materials of C horizon, and the other is the atmospheric deposition of the smelting flue gas dust.

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

    PubMed

    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.

  18. 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.

    PubMed

    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.

  19. 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

    USGS Publications Warehouse

    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.

  20. 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

    NASA Astrophysics Data System (ADS)

    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 (P<0.00l) in comparison with that on the f-Liit fly of Prishtina and Luki. The concentration of Pb of fruit 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 (P<0.00l). ALA-D activity was also inhibited in the homogenate of Prishtina fruit fly in comparison with Luki group (P<0.00l). The amount of proteins was significantly lower in Mitrovica fruit fly in comparison with that in control and Prishtina group. The hemoglobin value was relatively unchanged.

  1. Health hazard prospecting by modeling wind transfer of metal-bearing dust from mining waste dumps: application to Jebel Ressas Pb-Zn-Cd abandoned mining site (Tunisia).

    PubMed

    Ghorbel, Manel; Munoz, Marguerite; Solmon, Fabien

    2014-10-01

    This work presents a modeling approach to simulate spatial distribution of metal contamination in aerosols with evaluation of health hazard. This approach offers the advantage to be non-intrusive, less expensive than sampling and laboratory analyses. It was applied to assess the impact of metal-bearing dust from mining wastes on air quality for a nearby community and agricultural lands in Jebel Ressas (Tunisia) locality. Dust emission rates were calculated using existing parameterization adapted to the contamination source composed of mining wastes. Metal concentrations were predicted using a Gaussian model (fugitive dust model) with, as input: emission rates, dump physical parameters and meteorological data measured in situ for 30 days in summertime. Metal concentration maps were built from calculated PM10 particle concentrations. They evidence the areas where Pb and Cd concentrations exceeded WHO guidelines (0.5 and 0.005 µg/m(3), respectively). Maximum concentrations of Pb and Cd in PM10 are, respectively, of 5.74 and 0.0768 µg/m(3) for measured wind speed values up to 22 m/s. Preferential areas of contamination were determined in agricultural lands to the NW from the source dump where Pb and Cd exceeded guidelines up to a distance of 1,200 m. The secondary spreading directions were SW and E, toward the village. Health hazard prospecting shown that a major part of the village was exposed to contaminated dust and that daily hazard quotient (HQ) values reached locally 118 and 158, respectively, for Pb and Cd during the study period. However, HQ variations in the village are high, both temporally and geographically.

  2. Distribution and accumulation of Cd, Cu, Hg, Pb and Zn in the surface sediments of El Tobari Lagoon, central-East Gulf of California: An ecosystem associated with agriculture and aquaculture activities.

    PubMed

    Jara-Marini, M E; Tapia-Alcaraz, J N; Dumer-Gutiérrez, J A; García-Rico, L; García-Hernández, J; Páez-Osuna, F

    2013-01-01

    The purpose of this research is to provide a comprehensive assessment of the concentration levels and spatial variability of cadmium (Cd), copper (Cu), mercury (Hg), lead (Pb) and zinc (Zn) in El Tobari Lagoon in surface sediments during two seasons for several geochemical variables that could explain the observed heavy metal variability. Seventy-two surface sediments samples were collected in 12 different sites of the El Tobari Lagoon. Sediment samples were dried and subjected to acid extraction using a microwave system and five metals (Cd, Cu, Hg, Pb and Zn) were measured using atomic adsorption spectrometry. A certificate sediment material and blanks were used as quality control purposes. The enrichment factor (EF) and the index of geoaccumulation (Igeo) were calculated as index of metals contamination for the sediments, using aluminum as the conservative element. The five metals examined in sediments from El Tobari Lagoon exhibited a linear correlation with Al as result of the large specific surface areas of these sediment components and the chemical affinities between them. The metals contents in sites of the El Tobari Lagoon were variable, and Cd, Cu and Hg presented a seasonal behavior. The enrichment factor and index of geoaccumulation analysis indicated that Cd and Hg exhibited a certain extent (EF for Cd ranged from 4.10 to 10.29; EF for Hg ranged from 2.77 to 12.89) of anthropogenic pollution, while Cu showed sporadic (EF ranged from 0.43 to 2.54) anthropogenic contamination. The highest concentrations of Cd, Cu and Hg were found in the sites that regularly received discharge effluents from agriculture and aquaculture.

  3. Differential effects of AM fungal isolates on Medicago truncatula growth and metal uptake in a multimetallic (Cd, Zn, Pb) contaminated agricultural soil.

    PubMed

    Redon, Paul-Olivier; Béguiristain, Thierry; Leyval, Corinne

    2009-03-01

    Toxic metal accumulation in soils of agricultural interest is a serious problem needing more attention, and investigations on soil-plant metal transfer must be pursued to better understand the processes involved in metal uptake. Arbuscular mycorrhizal (AM) fungi are known to influence metal transfer in plants by increasing plant biomass and reducing metal toxicity to plants even if diverging results were reported. The effects of five AM fungi isolated from metal contaminated or non-contaminated soils on metal (Cd, Zn) uptake by plant and transfer to leachates was assessed with Medicago truncatula grown in a multimetallic contaminated agricultural soil. Fungi isolated from metal-contaminated soils were more effective to reduce shoot Cd concentration. Metal uptake capacity differed between AM fungi and depended on the origin of the isolate. Not only fungal tolerance and ability to reduce metal concentrations in plant but also interactions with rhizobacteria affected heavy metal transfer and plant growth. Indeed, thanks to association with nodulating rhizobacteria, one Glomus intraradices inoculum increased particularly plant biomass which allowed exporting twofold more Cd and Zn in shoots as compared to non-mycorrhizal treatment. Cd concentrations in leachates were variable among fungal treatments, but can be significantly influenced by AM inoculation. The differential strategies of AM fungal colonisation in metal stress conditions are also discussed. PMID:19169716

  4. Ex situ synthesis and optical properties of ZnO-PbS nanocomposites

    NASA Astrophysics Data System (ADS)

    Ntwaeaborwa, O. M.; Kroon, R. E.; Kumar, V.; Dubroca, T.; Ahn, J.-P.; Park, J.-K.; Swart, H. C.

    2009-11-01

    Zinc oxide (ZnO) and lead sulphide (PbS) nanoparticles separately synthesized by a precipitation method were combined by an ex situ route to prepare ZnO-PbS nanocomposites with different molar ratios of ZnO and PbS. The structure and morphology of the ZnO, PbS and ZnO-PbS samples were analyzed with X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM). A UV-vis spectrophotometer was used to collect the absorption and 325 nm He-Cd and 488 nm Ar lasers were used to collect the photoluminescence data from the samples. ZnO nanoparticles showed a broad and stable emission peak at ˜570 nm, while a strongly quantum confined emission from PbS nanoparticles was detected at ˜1344-1486 nm. The ZnO-PbS nanocomposites exhibited dual emission in the visible and near-infrared (NIR) regions that is associated with defects and recombination of excitonic centres in the ZnO and PbS nanoparticles, respectively. The PL intensity of the visible emission from the ZnO-PbS nanocomposite was shown to increase when the ZnO to PbS molar ratio was 5:1 and the emission was almost quenched at molar ratios of 1:1 and 1:5. For different molar ratios of ZnO to PbS, the PL intensity of the NIR emission from the ZnO-PbS nanocomposites was more intense than that of PbS nanoparticles.

  5. Sequential injection anodic stripping voltammetry with monosegmented flow and in-line UV digestion for determination of Zn(II), Cd(II), Pb(II) and Cu(II) in water samples.

    PubMed

    Siriangkhawut, Watsaka; Grudpan, Kate; Jakmunee, Jaroon

    2011-06-15

    A cost-effective sequential injection system incorporating with an in-line UV digestion for breakdown of organic matter prior to voltammetric determination of Zn(II), Cd(II), Pb(II) and Cu(II) by anodic stripping voltammetry (ASV) on a hanging mercury drop electrode (HMDE) of a small scale voltammetric cell was developed. A low-cost small scale voltammetric cell was fabricated from disposable pipet tip and microcentrifuge tube with volume of about 3 mL for conveniently incorporated with the SI system. A home-made UV digestion unit was fabricated employing a small size and low wattage UV lamps and flow reactor made from PTFE tubing coiled around the UV lamp. An in-line single standard calibration or a standard addition procedure was developed employing a monosegmented flow technique. Performance of the proposed system was tested for in-line digestion of model water samples containing metal ions and some organic ligands such as strong organic ligand (EDTA) or intermediate organic ligand (humic acid). The wet acid digestion method (USEPA 3010a) was used as a standard digestion method for comparison. Under the optimum conditions, with deposition time of 180 s, linear calibration graphs in range of 10-300 μg L(-1) Zn(II), 5-200 μg L(-1) Cd(II), 10-200 μg L(-1) Pb(II), 20-400 μg L(-1) Cu(II) were obtained with detection limit of 3.6, 0.1, 0.7 and 4.3 μg L(-1), respectively. Relative standard deviation were 4.2, 2.6, 3.1 and 4.7% for seven replicate analyses of 27 μg L(-1) Zn(II), 13 μg L(-1) Cd(II), 13 μg L(-1) Pb(II) and 27 μg L(-1) Cu(II), respectively. The system was validated by certified reference material of trace metals in natural water (SRM 1640 NIST). The developed system was successfully applied for speciation of Cd(II) Pb(II) and Cu(II) in ground water samples collected from nearby zinc mining area.

  6. Primary fragmentation pathways of gas phase [M(uracil-H)(uracil)]+ complexes (M=Zn, Cu, Ni, Co, Fe, Mn, Cd, Pd , Mg, Ca, Sr, Ba, and Pb): loss of uracil versus HNCO.

    PubMed

    Ali, Osama Y; Randell, Nicholas M; Fridgen, Travis D

    2012-04-23

    Complexes formed between metal dications, the conjugate base of uracil, and uracil are investigated by sustained off-resonance irradiation collision-induced dissociation (SORI-CID) in a Fourier transform ion cyclotron resonance (FTICR) mass spectrometer. Positive-ion electrospray spectra show that [M(Ura-H)(Ura)](+) (M=Zn, Cu, Ni, Co, Fe, Mn, Cd, Pd, Mg, Ca, Sr, Ba, or Pb) is the most abundant ion even at low concentrations of uracil. SORI-CID experiments show that the main primary decomposition pathway for all [M(Ura-H)(Ura)](+) , except where M=Ca, Sr, Ba, or Pb, is the loss of HNCO. Under the same SORI-CID conditions, when M is Ca, Sr, Ba, or Pb, [M(Ura-H)(Ura)](+) are shown to lose a molecule of uracil. Similar results were observed under infrared multiple-photon dissociation excitation conditions, except that [Ca(Ura-H)(Ura)](+) was found to lose HNCO as the primary fragmentation product. The binding energies between neutral uracil and [M(Ura-H)](+) (M=Zn, Cu, Ni, Fe, Cd, Pd ,Mg, Ca, Sr Ba, or Pb) are calculated by means of electronic-structure calculations. The differences in the uracil binding energies between complexes which lose uracil and those which lose HNCO are consistent with the experimentally observed differences in fragmentation pathways. A size dependence in the binding energies suggests that the interaction between uracil and [M(Ura-H)](+) is ion-dipole complexation and the experimental evidence presented supports this. PMID:22447672

  7. Adsorption of Pb(II), Cu(II), Cd(II), Zn(II), Ni(II), Fe(II), and As(V) on bacterially produced metal sulfides.

    PubMed

    Jong, Tony; Parry, David L

    2004-07-01

    The adsorption of Pb(II), Cu(II), Cd(II), Zn(II), Ni(II), Fe(II) and As(V) onto bacterially produced metal sulfide (BPMS) material was investigated using a batch equilibrium method. It was found that the sulfide material had adsorptive properties comparable with those of other adsorbents with respect to the specific uptake of a range of metals and, the levels to which dissolved metal concentrations in solution can be reduced. The percentage of adsorption increased with increasing pH and adsorbent dose, but decreased with increasing initial dissolved metal concentration. The pH of the solution was the most important parameter controlling adsorption of Cd(II), Cu(II), Fe(II), Ni(II), Pb(II), Zn(II), and As(V) by BPMS. The adsorption data were successfully modeled using the Langmuir adsorption isotherm. Desorption experiments showed that the reversibility of adsorption was low, suggesting high-affinity adsorption governed by chemisorption. The mechanism of adsorption for the divalent metals was thought to be the formation of strong, inner-sphere complexes involving surface hydroxyl groups. However, the mechanism for the adsorption of As(V) by BPMS appears to be distinct from that of surface hydroxyl exchange. These results have important implications to the management of metal sulfide sludge produced by bacterial sulfate reduction.

  8. A rapid, partial leach and organic separation for the sensitive determination of Ag, Bi, Cd, Cu, Mo, Pb, Sb, and Zn in surface geologic materials by flame atomic absorption

    USGS Publications Warehouse

    Viets, J.G.; Clark, J.R.; Campbell, W.L.

    1984-01-01

    A solution of dilute hydrochloric acid, ascorbic acid, and potassium iodide has been found to dissolve weakly bound metals in soils, stream sediments, and oxidized rocks. Silver, Bi, Cd, Cu, Mo, Pb, Sb, and Zn are selectively extracted from this solution by a mixture of Aliquat 336 (tricaprylyl methyl ammonium chloride) and MIBK (methyl isobutyl ketone). Because potentially interfering major and minor elements do not extract, the organic separation allows interference-free determinations of Ag and Cd to the 0.05 ppm level, Mo, Cu, and Zn to 0.5 ppm, and Bi, Pb, and Sb to 1 ppm in the sample using flame atomic absorption spectroscopy. The analytical absorbance values of the organic solution used in the proposed method are generally enhanced more than threefold as compared to aqueous solutions, due to more efficient atomization and burning characteristics. The leaching and extraction procedures are extremely rapid; as many as 100 samples may be analyzed per day, yielding 800 determinations, and the technique is adaptable to field use. The proposed method was compared to total digestion methods for geochemical reference samples as well as soils and stream sediments from mineralized and unmineralized areas. The partial leach showed better anomaly contrasts than did total digestions. Because the proposed method is very rapid and is sensitive to pathfinder elements for several types of ore deposits, it should be useful for reconnaissance surveys for concealed deposits. ?? 1984.

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

    SciTech Connect

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

    2014-12-28

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

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

    PubMed

    Wilczek, Grazyna; Babczyńska, Agnieszka; Augustyniak, Maria; Migula, Paweł

    2004-12-01

    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.

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

    PubMed

    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. PMID:23361451

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

    PubMed

    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.

  13. 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.

    PubMed

    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. PMID:24054694

  14. 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.

    PubMed

    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.

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

    PubMed

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

    2011-01-01

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

  16. Band alignment of type I at (100)ZnTe/PbSe interface

    NASA Astrophysics Data System (ADS)

    Konovalov, Igor; Emelianov, Vitali; Linke, Ralf

    2016-06-01

    A junction of lattice-matched cubic semiconductors ZnTe and PbSe results in a band alignment of type I so that the narrow band gap of PbSe is completely within the wider band gap of ZnTe. The valence band offset of 0.27 eV was found, representing a minor barrier during injection of holes from PbSe into ZnTe. Simple linear extrapolation of the valence band edge results in a smaller calculated band offset, but a more elaborate square root approximation was used instead, which accounts for parabolic bands. PbSe was electrodeposited at room temperature with and without Cd2+ ions in the electrolyte. Although Cd adsorbs at the surface, the presence of Cd in the electrolyte does not influence the band offset.

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

    PubMed

    Karwowska, Ewa; Wojtkowska, Małgorzata; Andrzejewska, Dorota

    2015-12-15

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

  18. Concentration of Cu, Zn, Cr, Ni, Cd, and Pb in soil, sugarcane leaf and juice: residual effect of sewage sludge and organic compost application.

    PubMed

    Moretti, Sarah Mello Leite; Bertoncini, Edna Ivani; Vitti, André César; Alleoni, Luís Reynaldo Ferracciú; Abreu-Junior, Cassio Hamilton

    2016-03-01

    Many researchers have evaluated the effects of successive applications of sewage sludge (SS) on soil plant-systems, but most have not taken into account the residual effect of organic matter remaining from prior applications. Furthermore, few studies have been carried out to compare the effects of the agricultural use of SS and sewage sludge compost (SSC). Therefore, we evaluated the residual effect of SS and SSC on the heavy metal concentrations in soil and in sugarcane (Saccharum spp.) leaves and juice. The field experiment was established after the second harvesting of unburned sugarcane, when the organic materials were applied. The SS and SSC rates were (t ha(-1), dry base): 0, 12.5, 25, and 50; and 0, 21, 42, and 84, respectively. All element concentrations in the soil were below the standards established by São Paulo State environmental legislation. SS promoted small increases in Zn concentrations in soil and Cu concentrations in leaves. However, all heavy metals concentrations in the leaves were lower than the limits established for toxic elements and were in accordance with the limits established for micronutrients. There were reductions in the concentrations of Ni and Cu in soil and the concentration of Pb in juice, with increasing rates of SSC. The heavy metal concentrations were very low in the juice. Under humid tropical conditions and with short-term use, SS and SSC containing low heavy metal concentrations did not have negative effects on plants and soil.

  19. Concentration of Cu, Zn, Cr, Ni, Cd, and Pb in soil, sugarcane leaf and juice: residual effect of sewage sludge and organic compost application.

    PubMed

    Moretti, Sarah Mello Leite; Bertoncini, Edna Ivani; Vitti, André César; Alleoni, Luís Reynaldo Ferracciú; Abreu-Junior, Cassio Hamilton

    2016-03-01

    Many researchers have evaluated the effects of successive applications of sewage sludge (SS) on soil plant-systems, but most have not taken into account the residual effect of organic matter remaining from prior applications. Furthermore, few studies have been carried out to compare the effects of the agricultural use of SS and sewage sludge compost (SSC). Therefore, we evaluated the residual effect of SS and SSC on the heavy metal concentrations in soil and in sugarcane (Saccharum spp.) leaves and juice. The field experiment was established after the second harvesting of unburned sugarcane, when the organic materials were applied. The SS and SSC rates were (t ha(-1), dry base): 0, 12.5, 25, and 50; and 0, 21, 42, and 84, respectively. All element concentrations in the soil were below the standards established by São Paulo State environmental legislation. SS promoted small increases in Zn concentrations in soil and Cu concentrations in leaves. However, all heavy metals concentrations in the leaves were lower than the limits established for toxic elements and were in accordance with the limits established for micronutrients. There were reductions in the concentrations of Ni and Cu in soil and the concentration of Pb in juice, with increasing rates of SSC. The heavy metal concentrations were very low in the juice. Under humid tropical conditions and with short-term use, SS and SSC containing low heavy metal concentrations did not have negative effects on plants and soil. PMID:26879984

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

    PubMed

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

    2016-04-28

    Lead-zinc deposits are often difficult to classify because clear criteria are lacking. In recent years, new tools, such as Cd and Zn isotopes, have been used to better understand the ore-formation processes and to classify Pb-Zn deposits. Herein, we investigate Cd concentrations, Cd isotope systematics and Zn/Cd ratios in sphalerite from nine Pb-Zn deposits divided into high-temperature systems (e.g., porphyry), low-temperature systems (e.g., Mississippi Valley type [MVT]) and exhalative systems (e.g., sedimentary exhalative [SEDEX]). Our results showed little evidence of fractionation in the high-temperature systems. In the low-temperature systems, Cd concentrations were the highest, but were also highly variable, a result consistent with the higher fractionation of Cd at low temperatures. The δ(114/110)Cd values in low-temperature systems were enriched in heavier isotopes (mean of 0.32 ± 0.31‰). Exhalative systems had the lowest Cd concentrations, with a mean δ(114/110)Cd value of 0.12 ± 0.50‰. We thus conclude that different ore-formation systems result in different characteristic Cd concentrations and fraction levels and that low-temperature processes lead to the most significant fractionation of Cd. Therefore, Cd distribution and isotopic studies can support better understanding of the geochemistry of ore-formation processes and the classification of Pb-Zn deposits.

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

    PubMed

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

    2016-01-01

    Lead-zinc deposits are often difficult to classify because clear criteria are lacking. In recent years, new tools, such as Cd and Zn isotopes, have been used to better understand the ore-formation processes and to classify Pb-Zn deposits. Herein, we investigate Cd concentrations, Cd isotope systematics and Zn/Cd ratios in sphalerite from nine Pb-Zn deposits divided into high-temperature systems (e.g., porphyry), low-temperature systems (e.g., Mississippi Valley type [MVT]) and exhalative systems (e.g., sedimentary exhalative [SEDEX]). Our results showed little evidence of fractionation in the high-temperature systems. In the low-temperature systems, Cd concentrations were the highest, but were also highly variable, a result consistent with the higher fractionation of Cd at low temperatures. The δ(114/110)Cd values in low-temperature systems were enriched in heavier isotopes (mean of 0.32 ± 0.31‰). Exhalative systems had the lowest Cd concentrations, with a mean δ(114/110)Cd value of 0.12 ± 0.50‰. We thus conclude that different ore-formation systems result in different characteristic Cd concentrations and fraction levels and that low-temperature processes lead to the most significant fractionation of Cd. Therefore, Cd distribution and isotopic studies can support better understanding of the geochemistry of ore-formation processes and the classification of Pb-Zn deposits. PMID:27121538

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

    PubMed Central

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

    2016-01-01

    Lead-zinc deposits are often difficult to classify because clear criteria are lacking. In recent years, new tools, such as Cd and Zn isotopes, have been used to better understand the ore-formation processes and to classify Pb-Zn deposits. Herein, we investigate Cd concentrations, Cd isotope systematics and Zn/Cd ratios in sphalerite from nine Pb-Zn deposits divided into high-temperature systems (e.g., porphyry), low-temperature systems (e.g., Mississippi Valley type [MVT]) and exhalative systems (e.g., sedimentary exhalative [SEDEX]). Our results showed little evidence of fractionation in the high-temperature systems. In the low-temperature systems, Cd concentrations were the highest, but were also highly variable, a result consistent with the higher fractionation of Cd at low temperatures. The δ114/110Cd values in low-temperature systems were enriched in heavier isotopes (mean of 0.32 ± 0.31‰). Exhalative systems had the lowest Cd concentrations, with a mean δ114/110Cd value of 0.12 ± 0.50‰. We thus conclude that different ore-formation systems result in different characteristic Cd concentrations and fraction levels and that low-temperature processes lead to the most significant fractionation of Cd. Therefore, Cd distribution and isotopic studies can support better understanding of the geochemistry of ore-formation processes and the classification of Pb-Zn deposits. PMID:27121538

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

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

    PubMed

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

    2007-05-01

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

  5. Influence of hydrology on heavy metal speciation and mobility in a Pb-Zn mine tailing.

    PubMed

    Kovács, Elza; Dubbin, William E; Tamás, János

    2006-05-01

    Among the inorganic toxicants of greatest concern in mine tailings, Pb, Zn, Cu, Cd and As figure prominently due to their abundance and potential toxicity. Here we report on their biolability and solid-phase speciation in two sediment cores subject to variable hydrological regimes at an abandoned pyritic mine tailing. The oxic conditions of well-drained sediments induced pyrite oxidation and the subsequent liberation of H+, SO4(2-) and considerable quantities of Fe(III), which precipitated as goethite. Solubility of Pb, Zn, Cu and Cd was closely coupled to pH and goethite presence. Metal lability was particularly low in zones of neutralization, formed by the accumulation of calcite, first carried then deposited by percolating waters in both saturated and unsaturated cores. We conclude that differential hydrology induces variable heavy metal speciation and biolability in Pb-Zn mine tailings, and suggest that site-specific risk assessments must account for past and present hydrological regimes.

  6. Impacts of anthropogenic pressures on the water quality of the Gironde Estuary (SW France) from the Urban Agglomeration of Bordeaux: spatial characterization and inputs of trace metal elements (Ag, As, Cd, Cu, Pb and Zn)

    NASA Astrophysics Data System (ADS)

    Kessaci, Kahina; Coynel, Alexandra; Blanc, Gérard; Deycard, Victoria N.; Derriennic, Hervé; Schäfer, Jörg

    2014-05-01

    Recent European legislation (2000/60/CE) has listed eight trace metal elements as priority toxic substances for water quality. Urban metal inputs into hydrosystems are of increasing interest to both scientists and managers facing restrictive environmental protection policies, population increase and changing metal applications. The Gironde Estuary (SW France; 625 km2) is known for its metal/metalloid pollution originating from industrial (e.g. Cd, Zn, Cu, As, Ag, Hg) or agricultural sources (e.g. Cu) in the main fluvial tributaries (Garonne and Dordogne Rivers). However, little peer-reviewed scientific work has addressed the impact of urban sources on the Gironde Estuary, especially the Urban Agglomeration of Bordeaux (~1 million inhabitants) located on the downstream branch of the Garonne River. In this study, a snapshot sampling campaign was performed in 2011 for characterizing the spatial distribution of dissolved and particulate metal/metalloid (As, Ag, Cd, Pb, Zn, Cu) concentrations in three suburban watersheds: the Jalle of Blanquefort (330 km2), Eau Bourde (140 km2), and Peugue (112 km2). Furthermore, particulate metal Enrichment Factors (EF) were calculated using local geochemical background measured at the bottom of a sediment core (492 cm). Results indicated that metal concentrations displayed a high spatial variability depending on the suburban watershed and the studied element. Local concentrations anomalies were observed for: (i) As in the Eau Bourde River in dissolved (4.2 μg/l) and particulate phases (246 mg/kg; EF= 20) and attributed to a nearby industrial incinerator; (ii) Zn in the Peugue River with maximum dissolved and particulate concentrations of 87 μg/l and 1580 mg/kg (EF=17), respectively, probably due to urban habitation runoff; (iii) Ag in the Jalle of Blanquefort River with high dissolved (74 ng/l) and particulate concentrations (33.7 mg/kg; EF=117) due to industrial activities in the downstream part. Based on hydro

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

    PubMed

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

    2016-04-01

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

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

    PubMed

    Nakayama, Shouta M M; Ikenaka, Yoshinori; Hamada, Kyohei; Muzandu, Kaampwe; Choongo, Kennedy; Teraoka, Hiroki; Mizuno, Naoharu; Ishizuka, Mayumi

    2011-01-01

    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. PMID:20971538

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

    PubMed

    Nakayama, Shouta M M; Ikenaka, Yoshinori; Hamada, Kyohei; Muzandu, Kaampwe; Choongo, Kennedy; Teraoka, Hiroki; Mizuno, Naoharu; Ishizuka, Mayumi

    2011-01-01

    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.

  10. Preparation of isotopic Zn and Cd targets

    NASA Astrophysics Data System (ADS)

    Fan, Qiwen; Xu, Guoji

    2008-06-01

    nat,68Zn and natCd have been reduced from their oxides with high yields (about 90%) using carbon as reductant. A water-cooled copper pin collector was used resulting in higher yield and better reproducibility. natZn and nat, 113, 116Cd targets of 20-3000 μg/cm 2 on carbon backings of 20 μg/cm 2 have been deposited by focused ion beam sputtering. 67, 68, 70Zn targets of 200-400 μg/cm 2 on iron backings of about 1.3 mg/cm 2 have been prepared using a rotating substrate setup to improve target homogeneity. Using a special rolling technique, 64, 66, 68, 70Zn and 110, 114, 116Cd have also been rolled to thin foils.

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

    PubMed

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

    2016-08-20

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

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

    PubMed

    Shahbazi, Yasser; Ahmadi, Farhad; Fakhari, Farnoosh

    2016-02-01

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

  13. Study on the relationship between speciation of heavy metals and their ecotoxicity. I. Toxicity of Cu, Cd, Pb and Zn in seawater to three marine algae in the presence of different complexation agents

    NASA Astrophysics Data System (ADS)

    Zhang, Manping; Wang, Juying; Bao, Junbo

    1992-09-01

    Heavy metal is a main pollutant in the marine ecosystem, so study on the effect of heavy metal on phytoplankton is important. Algae ( Chaetoceros sp., Dunaliella sp., Dicrateria zhanjiangenis Hu. var. sp.) were laboratory cultured to observe the effect of heavy metals on their growth. The effect of different metal ion concentration, the detoxication effect of complexation agents and the growth of algae in different media and different nutrition levels were studied to evaluate the effect of metal speciation. It is proved that trace amount of heavy metals can stimulate the growth of algae cells but that high concentration is lethal. The sequence of toxicity is Cd2+>Zn2+>Pb2+. In ordinary nutrition conditions, the detoxication sequence of complexation agents to Chaetoceros sp. is EDTA >sodium salicylate>sodium oxalate >sodium citrate>sulfanilic acid>O-phenanthroline. This is in good conformity with the stability constant sequence of these agents with copper and good evidence that toxicity of metal ion is related to its activity and not to its total concentration.

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

    NASA Astrophysics Data System (ADS)

    Nomngongo, Philiswa N.; Ngila, J. Catherine

    2014-08-01

    This study reports a simple and efficient method for the determination of trace Cd, Cu, Fe, Pb and Zn in diesel and gasoline samples by inductively coupled plasma mass spectrometry after matrix removal and analyte pre-concentration using hollow fiber-solid phase microextraction (HF-SPME). The optimization of HF-SPME procedure was carried out using two-level full factorial and central composite designs. Four factors (variables), that are, sample solution pH, acceptor phase amount, extraction time and eluent concentration were optimized. Under the optimized experimental conditions, the precision was ≤ 3% (C = 10 μg L- 1, n = 15), limits of detection and quantification ranged from 0.1 to 0.3 μg L- 1 and 0.3-0.9 μg L- 1, respectively, and the maximum preconcentration factor was 30. The HF-SPME method was applied for the determination of trace metals in real gasoline and diesel samples.

  15. 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.

    PubMed

    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.

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

    PubMed

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

    2016-09-15

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

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

    PubMed

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

    PubMed

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

    2016-07-01

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

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

    PubMed

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

    2016-07-01

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

  20. Solar paint of ZnO/CdS and ZnO/CdSe based on commercial ZnO

    NASA Astrophysics Data System (ADS)

    Guo, Yi; Zhang, Xiang; Li, Yanhong; Li, Yanmei; Hu, Chunli; Zhou, Xingfu

    2016-03-01

    We report a facile and cheap route to the fabrication of ZnO/CdS and ZnO/CdSe based on commercial ZnO particles. The obtained product can be directly brush printed as solar paint. The results show that the solar cell based on the mixture of ZnO/CdS and ZnO/CdSe have a better light absorption and electron transport ability, and a high power conversion efficiency (PCE) of 1.36% was obtained, which is the highest PCE reported for inorganic paint-based solar cells to date. This method greatly simplifies the process of the solar cell fabrication and opens a door toward the cheap and printable solar paint based on commercial available materials.

  1. Resistive switching properties in CdZnTe films

    SciTech Connect

    Zha, Gangqiang; Lin, Yun; Tan, Tingting; Jie, Wanqi; Zeng, Dongmei

    2015-02-09

    The ternary II–VI compound semiconductor cadmium zinc telluride (CdZnTe) has bi-stable conduction characteristics. In this letter, CdZnTe films are grown on indium tin oxide (ITO) substrates by radio frequency magnetron sputtering. The current-voltage characteristics show that there is resistive switching in a structure consisting of an 800-nm-thick CdZnTe film, an Au Schottky contact, and an ITO bottom electrode. The electroresistance in Au/CdZnTe/ITO may be related to the polarization of the CdZnTe film and the Schottky contact.

  2. Native plant communities in an abandoned Pb-Zn mining area of northern Spain: implications for phytoremediation and germplasm preservation.

    PubMed

    Barrutia, O; Artetxe, U; Hernández, A; Olano, J M; García-Plazaola, J I; Garbisu, C; Becerril, J M

    2011-03-01

    Plants growing on metalliferous soils from abandoned mines are unique because of their ability to cope with high metal levels in soil. In this study, we characterized plants and soils from an abandoned Pb-Zn mine in the Basque Country (northern Spain). Soil in this area proved to be deficient in major macronutrients and to contain toxic levels of Cd, Pb, and Zn. Spontaneously growing native plants (belonging to 31 species, 28 genera, and 15 families) were botanically identified. Plant shoots and rhizosphere soil were sampled at several sites in the mine, and analyzed for Pb, Zn and Cd concentration. Zinc showed the highest concentrations in shoots, followed by Pb and Cd. Highest Zn concentrations in shoots were found in the Zn-Cd hyperaccumulator Thlaspi caerulescens (mean = 18,254 mg Zn kg(-1) DW). Different metal tolerance and accumulation patterns were observed among the studied plant species, thus offering a wide germplasm assortment for the suitable selection of phytoremediation technologies. This study highlights the importance of preserving metalliferous environments as they shelter a unique and highly valuable metallicolous biodiversity.

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

    PubMed

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

    2016-04-01

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

  4. Photoluminescence study of ZnS and ZnS:Pb nanoparticles

    SciTech Connect

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

    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.

  5. Limitation of Pb and Cd uptake by pine

    SciTech Connect

    Ostrowska, A.; Porebska, G.; Szczubialka, Z.

    2006-07-15

    Model experiments were carried out using 1-year-old pine plants grown in water cultures with the aim of investigating whether and to what extent the accumulation of Pb and Cd in plants can be decreased through decreasing the nutrient solution concentration, supplementing with forest soil, supplementing with calcium carbonate, and addition of brown coal. It was found that with increased doses of Pb and Cd in water cultures pine plants take up more of those elements. Whereas Pb accumulates mainly in the roots, about half of the Cd is transported to the above-ground part of the plants. Addition of Pb, Cd, and forest soil to the nutrition medium increased Pb uptake by pine plants compared to the control treatment. The effect of soil addition was not that evident in the case of Cd uptake. Furthermore, it was observed that addition of brown coal resulted in a slight increase of Pb accumulation in the shoots and in a considerable decrease of its accumulation in roots. A higher increase of Cd accumulation in the shoots was observed after brown coal was added to the nutrient solution. The amounts of Cd and Pb accumulated in plants, mainly in the shoots, decreased following the addition of CaCO{sub 3}. When CaCO{sub 3} and brown coal were added jointly, this effect was markedly more pronounced. The decrease of nutrient supply (down to one-quarter of the original concentration) increased the content of Pb, especially in the roots; for Cd, changes in its content in pine were not univocal.

  6. Long-term changes of metal contents in two metallophyte species (Olkusz area of Zn-Pb ores, Poland).

    PubMed

    Kicińska, Alicja; Gruszecka-Kosowska, Agnieszka

    2016-06-01

    The authors present the changes of the As, Cd, Fe, Mn, Pb and Zn contents in two plant-considered metallophytes: common bent Agrostis capillaris (blades) and birch Betula pendula (leaves and seeds), recorded in a Zn-Pb industrial region of Olkusz (Poland) in 1994 and 2014. The highest amounts of Cd (12 ppm) and Zn (2524 ppm) in the common bent occur in the vicinity of the mining and metallurgical works 'Bolesław' in Bukowno. However, these values are significantly lower than those in 1994: Cd by 87 % and Zn by 52 %. The highest contents of Fe (2674 ppm), Mn (130 ppm) and Pb (334 ppm) in this grass species are in the vicinity of the closed Olkusz mine. These contents have increased in comparison with the 1994 figures: Fe by 56 %, Mn by 120 % and Pb by 6 %. In the birch leaves, the metal contents averaged for four sites are the following: As 2.1, Cd 6.5, Fe 261, Mn 110, Pb 70 and Zn 1657 ppm, being lower from the figures in 1994. The highest As, Fe and Pb contents of birch leaves occur in the habitat closest to the former Olkusz mine, while those of Cd, Mn and Zn in the habitat distant at 100 m from the active plant in Bukowno. The common bent grass generates better resistance mechanisms against the metals than does the birch. In the birch leaves, the contents of the metals are significantly lower than those of the grass blades, but higher from those of the birch seeds collected from the same tree individuals. It is a proof of good functioning of the mechanisms preventing excessive metal amounts from the cell metabolism and of the presence of physiological barriers protecting birch seeds as the generative organs. PMID:27165603

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

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

    PubMed

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

    2011-01-01

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

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

    PubMed

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

    2011-01-01

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

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

    PubMed Central

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

    2015-01-01

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

  11. Sulphide and supergene nonsulphide Zn-Pb deposits of the southern Kootenay Arc, British Columbia, Canada

    NASA Astrophysics Data System (ADS)

    Paradis, S.; Simandl, G. J.

    2009-05-01

    The Kootenay Arc (KA) hosts a large number of carbonate-hosted base metal (Zn-Pb) deposits. These deposits occur mainly within the dolomitized limestone of the Lower Cambrian Badshot Formation (or its equivalent the Reeves Member of the Laib Formation), and the Upper Cambrian to Lower Ordovician Nelway Formation. They range in size from 6-10 million tonnes with average grades of 3-4% Zn, 1-2% Pb, 0.4% Cd and traces of Ag. The deposits, their dolomitic envelopes, and the limestone hostrock lie within secondary isoclinal folds along the limbs of regional anticlinal structures. Most of the deposits are stratabound lenticular concentrations of sphalerite, galena, pyrite, local pyrrhotite and rare arsenopyrite in isoclinally folded dolomitized or silicified carbonate layers. Brecciated zones are common within the more massive sulphide mineralization. Several deposits are past producers (e.g., Reeves MacDonald, Jersey, and HB) and others are advanced prospects. They are interpreted as metamorphosed MVT- or Irish-type Pb-Zn deposits. The main concentrations of these deposits define the Salmo and Duncan camps. The near-surface portions of these carbonate-hosted sulphide deposits are weathered and strongly oxidized (supergene environment). They consist of extensive Zn- and Pb-bearing iron oxide gossans and base metal-bearing nonsulphide mineralization. The most common nonsulphide minerals are goethite, hematite, hemimorphite, smithsonite, cerussite, anglesite, and hydrozincite. The Reeves MacDonald, Jersey-Emerald, Lomond, and Oxide group of deposits are the best examples of carbonate-hosted nonsulphide base metal (CHNSBM) deposits in the KA. The shape, mineralogy and paragenesis of the known CHNSBM deposits are indicative of direct-replacement of sulphides by nonsulphide base metal-bearing minerals. Zn-rich (low Pb) CHNSBM deposits commonly form by interaction of Zn-rich fluids with carbonate wallrock (replacement process). Such deposits (consisting of "white ore") may

  12. Distinguishing regional- and local-scale metasomatic systems at the Prairie Downs Zn-Pb deposit

    NASA Astrophysics Data System (ADS)

    White, Alistair J. R.; Pearce, Mark A.; Meadows, Holly R.

    2016-10-01

    Geochemical alteration in mafic rocks of the Fortescue Group around the Prairie Downs Zn-Pb-(Cu-Ag) deposit, Western Australia, is the result of two overprinting metasomatic systems. The first, a regional-scale event, well documented across the Fortescue Basin to the north, resulted in extensive depletion in alkalis, Mg, and heavier first transition series metals (Mn-Zn), and formation of mineral assemblages progressing towards pure epidote/pumpellyite-quartz end-members. The second, more localised event, was associated with Zn-Pb-(Cu-Ag) mineralisation and resulted in Ca-loss accompanied by enrichment in a broad transition metal and metalloid suite (Zn-Pb-Sn-Ag-K-Ba-Tl-Sb-Ge-U-Th-Cd-Hg-Se-REE) that is comparable to many sedimentary exhalative (SEDEX) systems, and possibly represents modification or remobilisation of an earlier ore system. The mineralisation-related alteration was superimposed on the earlier regional-scale metasomatism: previously unaltered basalts underwent Zn-bearing chlorite and biotite growth, with loss of amphibole and epidote; regionally metasomatised rocks now comprise assemblages dominated by quartz, muscovite and baileychlore (Zn chlorite). These altered basalts do not contain any sulphide minerals and all Zn is hosted within chlorite in a broad halo around the main sulphide zones, thereby providing a larger exploration target. Geochemical modelling with HCh indicates that the observed alteration assemblages can be generated through interaction of rocks with large volumes of a saline, Zn-K-bearing fluid (fluid/rock ~ 1000). This study highlights the importance of understanding the regional geochemical background when investigating local metasomatic systems in order to correctly characterise them, determine their origin and position in a regional tectonic framework, and to correctly identify vectors towards mineralisation to aid future exploration.

  13. 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.

    PubMed

    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. PMID:16629156

  14. Heavy metal distribution and chemical speciation in tailings and soils around a Pb-Zn mine in Spain.

    PubMed

    Rodríguez, L; Ruiz, E; Alonso-Azcárate, J; Rincón, J

    2009-02-01

    Soil pollution by lead, zinc, cadmium and copper was characterized in the mine tailings and surrounding soils (arable and pasture lands) of an old Spanish Pb-Zn mine. Sixty soil samples were analyzed, determining the total metal concentration by acid digestion and the chemical fractionation of Pb and Zn by the modified BCR sequential extraction method. Samples belonging to mine waste areas showed the highest values, with mean concentrations of 28,453.50 mg kg(-1) for Pb, 7000.44 mg kg(-1) for Zn, 20.57 mg kg(-1) for Cd and 308.48 mg kg(-1) for Cu. High concentrations of Pb, Zn and Cd were found in many of the samples taken from surrounding arable and pasture lands, indicating a certain extent of spreading of heavy metal pollution. Acidic drainage and wind transport of dust were proposed as the main effects causing the dispersion of pollution. Sequential extraction showed that most of the Pb was associated with non-residual fractions, mainly in reducible form, in all the collected samples. Zn appeared mainly associated with the acid-extractable form in mine tailing samples, while the residual form was the predominant one in samples belonging to surrounding areas. Comparison of our results with several criteria reported in the literature for risk assessment in soils polluted by heavy metals showed the need to treat the mine tailings dumped in the mine area.

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

    PubMed

    Park, Jin Hee; Chon, Hyo-Taek

    2016-06-01

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

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

    PubMed

    Park, Jin Hee; Chon, Hyo-Taek

    2016-06-01

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

  17. ZnCdMgSe-Based Semiconductors for Intersubband Devices

    SciTech Connect

    Tamargo, Maria C.

    2008-11-13

    This paper presents a review of recent results on the application of ZnCdMgSe-based wide bandgap II-VI compounds to intersubband devices such as quantum cascade lasers and quantum well infrared photodetectors operating in the mid-infrared region. The conduction band offset of ZnCdSe/ZnCdMgSe quantum well structures was determined from contactless electroreflectance measurements to be as high as 1.12 eV. FT-IR was used to measure intersubband absorption in multi-quantum well structures in the mid-IR range. Electroluminescence at 4.8 {mu}m was observed from a quantum cascade emitter structure made from these materials. Preliminary results are also presented on self assembled quantum dots of CdSe on ZnCdMgSe, and novel quantum well structures with metastable binary MgSe barriers.

  18. Palaeomagnetism of the Howards Pass Zn-Pb deposits, Yukon, Canada

    NASA Astrophysics Data System (ADS)

    Kawasaki, K.; Symons, D. T. A.

    2012-07-01

    The Howards Pass district is located in the Selwyn Basin, Yukon. The district consists of >15 laminated clastic-dominated (CD) sphalerite-galena (Zn-Pb) deposits in the 'zinc corridor' that trends northwest-southeast and extends for ˜35 km. The stratiform mineralized zone, the Active Member, is hosted in carbonaceous cherts and black shales of the Early Silurian Road River Group. Using mostly thermal and then alternating field step demagnetization isolated a stable characteristic remanent magnetization (ChRM) by the core-magnetization-angle method from 18 sites (339 specimens) in 18 variably oriented exploration drill hole cores from 6 Zn-Pb mineralized panels. Rock magnetic analyses show that the main remanence carriers are single- or pseudosingle-domain pyrrhotite and titanomagnetite. The deposits' mean ChRM direction yields a pole position of either ˜170 Ma on the North American apparent polar wander path or ˜162 Ma on a corrected path for the Intermontane Belt (IMB) terranes. A negative palaeomagnetic fold test indicates that the mineralization's ChRM is post-folding, setting a minimum age for regional metamorphic deformation of ˜170 ± 20 Ma and supporting an Early Jurassic arrival for the IMB's collision and accretion to North America. An autochthonous or para-autochthonous North American tectonic model is favoured for the ChRM of the metamorphosed Selwyn Basin strata rather than an allochthonous IMB model. Further, the palaeomagnetic age indicates that the coarse-grained Zn-Pb mineralization in fine fractures that cut the laminated fine-grained Zn-Pb mineralization at Howards Pass at least was formed by remobilization during Middle Jurassic metamorphism.

  19. Matrix Effects on the MC-ICPMS Analysis of Zn and Cd Isotopes

    NASA Astrophysics Data System (ADS)

    Shiel, A. E.; Weis, D.; Barling, J.; Orians, K. J.

    2006-12-01

    In order to understand fractionation in heavy stable isotope systems, matrix and auto-matrix effects need to be carefully monitored as they have a major impact on the precision and accuracy of isotope measurement by MC-ICP-MS. Understanding their impact for any given isotopic system is an important aspect of method development. In this study we look at auto-matrix and matrix effects for Zn (Cu mass bias correction) and Cd (Ag mass bias correction). Zn and Cd have similarly high ionization potentials, 9.4 and 9.0 respectively, and ionization potentials for Cu and Ag are similar, 7.7 and 7.6 respectively, making for an interesting comparison. All experiments were performed on a Nu Plasma MC-ICP-MS with 5x molar concentration of matrix elements. Experiments were also performed at concentrations more representative of those likely to be found in purified samples. In addition, we tested auto-matrix effects for Cd and Zn by varying the concentration of the analyte and mass bias correcting element. Cd sensitivity is enhanced in the presence of Rb and Pb, and is suppressed in the presence of Al, Sr and Cs. Spiked Cd runs are isotopically lighter than un-spiked runs, as light as 0.4‰/amu. Ag sensitivity was enhanced by all matrix elements. Cu sensitivity is enhanced by Al, Sr and Ba, and Zn sensitivity is enhanced by the latter two and Pb. Zn spiked with Al, Sr and Pb, or with poorly matched Cu intensities is isotopically lighter than un-spiked standards, as light as 1.0‰/amu. Auto-matrix effects for Cd and Ag, if present, are within the analytical error. We demonstrate that the presence of matrix elements or differences in concentration of analyte and mass bias correcting element between sample and standard can produce fractionation that is not true. The matrix effect is also found to be variable, as replicate analyses do not always agree. Cd and Zn react differently to different matrix elements, demonstrating the need for independent evaluation of each isotopic system

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

    NASA Astrophysics Data System (ADS)

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

    2010-07-01

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

  1. Cd and Zn uptake kinetics in Daphnia magna in relation to Cd exposure history.

    PubMed

    Guan, Rui; Wang, Wen-Xiong

    2004-11-15

    The uptake kinetics of Cd and Zn in a freshwater cladoceran Daphnia magna after exposure to different concentrations of Cd for various durations was quantified. The accumulated Cd concentrations increased with ambient Cd concentration and exposure duration. As a detoxification mechanism, metallothioneins (MTs) were induced when the Cd preexposure condition was beyond the noneffect threshold. The MT induction was dependent on both Cd concentration and duration of preexposure. Increasing the Cd exposure concentration to 20 microg L(-1) for 3 d caused a 44% reduction in Cd assimilation efficiency (AE, the fraction assimilated by the animals after digestion) by the daphnids from the dietary phase, but a 2.4-fold increase in Zn AE. Generally, the dissolved metal uptake rate was not significantly affected by the different Cd preexposure regimes, except at a much higher Cd concentration (20 microg L(-1)) when the Zn influx was enhanced. Significant effects from Cd exposure on the ingestion rate of the daphnids were also observed. When the MT synthesis was not coupled with the accumulated Cd tissue burden (e.g., a delay in MT synthesis), apparent Cd toxicity on the feeding behavior and the Cd AE was observed, thus highlighting the importance of MTs in modifying the metal uptake kinetics of D. magna. Overall, daphnids responded to acute Cd exposure by reducing their Cd AE and ingestion, whereas they developed a tolerance to Cd following chronic exposure. The bioavailability of Zn was enhanced as a result of Cd preexposure. This study highlights the important influences of Cd preexposure history on the biokinetics and potential toxicity of Cd and Zn to D. magna.

  2. Enriching rice with Zn and Fe while minimizing Cd risk

    PubMed Central

    Slamet-Loedin, Inez H.; Johnson-Beebout, Sarah E.; Impa, Somayanda; Tsakirpaloglou, Nikolaos

    2015-01-01

    Enriching iron (Fe) and zinc (Zn) content in rice grains, while minimizing cadmium (Cd) levels, is important for human health and nutrition. Natural genetic variation in rice grain Zn enables Zn-biofortification through conventional breeding, but limited natural Fe variation has led to a need for genetic modification approaches, including over-expressing genes responsible for Fe storage, chelators, and transporters. Generally, Cd uptake and allocation is associated with divalent metal cations (including Fe and Zn) transporters, but the details of this process are still unknown in rice. In addition to genetic variation, metal uptake is sometimes limited by its bioavailability in the soil. The availability of Fe, Zn, and Cd for plant uptake varies widely depending on soil redox potential. The typical practice of flooding rice increases Fe while decreasing Zn and Cd availability. On the other hand, moderate soil drying improves Zn uptake but also increases Cd and decreases Fe uptake. Use of Zn- or Fe-containing fertilizers complements breeding efforts by providing sufficient metals for plant uptake. In addition, the timing of nitrogen fertilization has also been shown to affect metal accumulation in grains. The purpose of this mini-review is to identify knowledge gaps and prioritize strategies for improving the nutritional value and safety of rice. PMID:25814994

  3. 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.

    PubMed

    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 < 0.05) of the fields probably because of accumulation and adsorption in soil. The elemental concentrations in paddy soil as well as water was in the ranking order of Cd > 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.

  4. Interaction of Cu(2+), Pb (2+), Zn (2+) with trypsin: what is the key factor of their toxicity?

    PubMed

    Zhang, Tong; Zhang, Hao; Liu, Guiliang; Gao, Canzhu; Liu, Rutao

    2014-11-01

    Heavy metals possess great endangerment to environment even human health because of their indissolubility and bioaccumulation. The toxicity of heavy metal ions (Cu(2+), Pb(2+), Zn(2+)) to trypsin was investigated by fluorescence, synchronous fluorescence, UV-vis absorption, circular dichroism (CD) spectroscopy, isothermal titration calorimetry (ITC), and enzyme activity assay. The experimental results showed that toxic effect of heavy metal ions was due to their own characteristic, rather than the electric charges of the ion. Zn(2+) could not show the obvious toxicity to trypsin, while the structure and function of trypsin was damaged when the enzyme explored to Cu(2+) and Pb(2+). From the spectra results, we found that Cu(2+) would bind with trypsin, which lead to the fluorescence quenched and hydrophobicity increased. Pb(2+) could also change the structure and reduce the activity of trypsin in high concentration. In vitro measurement, the toxicity order of heavy metal ions to trypsin is: Cu(2+) > Pb(2+) > Zn(2+). In addition, isothermal titration calorimetry analysis proved that the interactions between Cu(2+), Pb(2+), Zn(2+) and trypsin were all spontaneous and exothermic, which indicated the adverse effect of these heavy metal ions to trypsin. PMID:25323557

  5. Analysis of Etched CdZnTe Substrates

    NASA Astrophysics Data System (ADS)

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

    2016-09-01

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

  6. Concentrations of Pb, Zn, and Cu in Taraxacum spp. in relation to urban pollution

    SciTech Connect

    Cook, C.M.; Lanaras, T.; Sgardelis, S.P.; Pantis, J.D. )

    1994-08-01

    The combustion of petroleum fuel and exhaust emissions are major sources of atmospheric pollution in cities which result in the deposition of toxic substances, particularly heavy metals, in the surface layers of soils. Lead in particular enters the environment from the use of tetraethyl lead as an antiknock agent for petrol engines constituting 21% of fine particles emitted from cars burning leaded petrol. Antiwear protectants incorporated in lubricants often contain Cd, Cr, Cu, Hg, Ni, Pb and/or Zn which are also released into the environment by inefficient engines and irresponsible dumping of engine oils. Zn from tyre wear and Cu from diesel engines also add considerably to the environmental metal burden. Lowering of the permitted lead content of petrol and the growing use of unleaded fuel are expected to lead to reductions in the environmental lead burden, however, until unleaded fuel becomes universally accepted lead contamination, particularly of roadside soils and vegetation is a major cause for concern. A direct relationship between car exhaust, the Pb content of needles of Abies alba and reduced growth has been observed and can extend hundreds of metres from major highways. Lead tolerance has been observed in higher plants growing mine waste soils and to a lesser extent on lead-contaminated roadside soils. Automobiles which are responsible for line sources of pollution emissions in rural and suburban areas have a more far-reaching impact on roadside vegetation, already under considerable stress, in urban areas. Information on heavy metal effects on vegetation in urban environments however, are scarce. Modeling and multivariate analysis of a few of the factors involved have provided only limited data related to plant performance in these complex environments. Therefore in this study, the extent of heavy metal pollution by Pb, Zn, Cu and Cd in soils and in dandelion plants in the city of Thessaloniki has been examined. 20 refs., 2 figs., 3 tabs.

  7. CdZnTe technology for gamma ray detectors

    SciTech Connect

    Stahle, Carl; Shi, Jack; Shu, Peter; Barthelmy, Scott; Parsons, Ann; Snodgrass, Steve

    1998-01-15

    CdZnTe detector technology has been developed at NASA Goddard for imaging and spectroscopy applications in hard x-ray and gamma ray astronomy. A CdZnTe strip detector array with capabilities for arc second imaging and spectroscopy has been built as a prototype for a space flight gamma ray burst instrument. CdZnTe detectors also have applications for medical imaging, environmental protection, transportation safety, nuclear safeguards and safety, nuclear non-proliferation, and national security. This can be accomplished from space and also from portable detectors on earth. One of the great advantages of CdZnTe is that the detectors can be operated at room temperature which eliminates the need for cryogenic cooling. CdZnTe detectors have good energy resolution (3.6 keV at 60 keV) and excellent spatial resolution (<100 microns). NASA Goddard has developed the fabrication technology to make a variery of planar, strip, and pixel detectors and integrated these detectors to high density electronics. We have built a 2x2 and a large area (60 cm{sup 2}, 36 detectors) 6x6 strip detector array. This paper will summarize the CdZnTe detector fabrication and packaging technology developed at Goddard.

  8. Synthesis, characterization and thermochemistry of synthetic Pb-As, Pb-Cu and Pb-Zn jarosites

    NASA Astrophysics Data System (ADS)

    Forray, Ferenc Lázár; Smith, A. M. L.; Navrotsky, A.; Wright, K.; Hudson-Edwards, K. A.; Dubbin, W. E.

    2014-02-01

    The enthalpy of formation from the elements of well characterized Pb-As, Pb-Cu, and Pb-Zn synthetic jarosites, corresponding to chemical formulas (H3O)0.68±0.03Pb0.32±0.002Fe2.86±0.14(SO4)1.69±0.08(AsO4)0.31±0.02(OH)5.59±0.28(H2O)0.41±0.02, (H3O)0.67±0.03Pb0.33±0.02Fe2.71±0.14Cu0.25±0.01(SO4)2±0.00(OH)5.96±0.30(H2O)0.04±0.002 and (H3O)0.57±0.03Pb0.43±0.02Fe2.70±0.14Zn0.21±0.01(SO4)2±0.00(OH)5.95±0.30(H2O)0.05±0.002, was measured by high temperature oxide melt solution calorimetry and gave ΔH°f = -3691.2 ± 8.6 kJ/mol, ΔH°f = -3653.6 ± 8.2 kJ/mol, and ΔH°f = -3669.4 ± 8.4 kJ/mol, respectively. Using estimated entropies, the standard Gibbs free energy of formation from elements at 298 K ΔG°f of the three compounds were calculated to be -3164.8 ± 9.1, -3131.4 ± 8.7, and -3153.6 ± 8.9 kJ/mol, respectively. Based on these free energies, their log Ksp values are -13.94 ± 1.89, -4.38 ± 1.81 and -3.75 ± 1.80, respectively. For this compounds, a log10{Pb2+}-pH diagram is presented. The diagram shows that the formation of Pb-As jarosite may decrease aqueous arsenic and lead concentrations to meet drinking water standards. The new thermodynamic data confirm that transformation of Pb-As jarosite to plumbojarosite is thermodynamically possible.

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

    NASA Astrophysics Data System (ADS)

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

    2013-04-01

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

  10. Photorefractivity in a Titanium Doped ZnCdTe Crystal

    NASA Technical Reports Server (NTRS)

    Davis, M.; Collins, L.; Dyer, K.; Tong, J.; Ueda, A.; Chen, H.; Chen, K.-T.; Burger, A.; Pan, Z.; Morgan, S. H.

    1997-01-01

    Single crystals of Zn(.04)Cd(.96)Te was grown by horizontal physical vapor transport (PVT) method and doped by annealing with TiTe2 powder at 600 C for six days. Photorefractive two-beam coupling, along with photoluminescence and absorption spectroscopy, were used to characterize the ZnCdTe:Ti crystal. At 1.32 micrometers, the photorefractive gain has been measured as a function of the grating period. A gain of about 0.16/cm was obtained at an intensity of about 0.1 W/sq cm. The results of this titanium doped ZnCdTe crystal are compared to that of vanadium-doped CdTe crystals reported previously.

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

    NASA Astrophysics Data System (ADS)

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

    2016-09-01

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

  12. Lack of Zn inhibition of Cd accumulation by rice (Oryza sativa L.) supports non-Zn transporter uptake of Cd

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Rice (Oryza sativa L.) grown on Cd contaminated soils has been linked to health problems in subsistence rice farmers in Japan and China. For other crops, normal geogenic Zn inhibits the increased uptake of Cd on contaminated soils. A study was conducted using a multi-chelator buffered nutrient sol...

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  14. Optical phonons in PbTe/CdTe multilayer heterostructures

    SciTech Connect

    Novikova, N. N.; Yakovlev, V. A.; Kucherenko, I. V.; Karczewski, G.; Aleshchenko, Yu. A.; Muratov, A. V.; Zavaritskaya, T. N.; Melnik, N. N.

    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.

  15. Tunable zinc interstitial related defects in ZnMgO and ZnCdO films

    SciTech Connect

    Li, Wanjun; Qin, Guoping; Fang, Liang E-mail: kchy@163.com; Ye, Lijuan; Wu, Fang; Ruan, Haibo; Zhang, Hong; Kong, Chunyang E-mail: kchy@163.com; Zhang, Ping

    2015-04-14

    We report tunable band gap of ZnO thin films grown on quartz substrates by radio frequency magnetron sputtering. The zinc interstitial (Zn{sub i}) defects in ZnO films were investigated by X-ray diffraction, Raman scattering, Auger spectra, first-principle calculations, and Hall measurement. Undoped ZnO film exhibits an anomalous Raman mode at 275 cm{sup −1}. We first report that 275 cm{sup −1} mode also can be observed in ZnO films alloyed with Mg and Cd, whose Raman intensities, interestingly, decrease and increase with increasing Mg and Cd alloying content, respectively. Combined with the previous investigations, it is deduced that 275 cm{sup −1} mode is attributed to Zn{sub i} related defects, which is demonstrated by our further experiment and theoretical calculation. Consequently, the concentration of Zn{sub i} related defects in ZnO can be tuned by alloying Mg and Cd impurity, which gives rise to different conductivity in ZnO films. These investigations help to further understand the controversial origin of the additional Raman mode at 275 cm{sup −1} and also the natural n-type conductivity in ZnO.

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

    PubMed

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

    2015-12-01

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

  17. CdZnTe background measurements at balloon altitudes

    NASA Astrophysics Data System (ADS)

    Parsons, Ann M.; Barthelmy, Scott D.; Bartlett, Lyle M.; Birsa, F. B.; Gehrels, Neil A.; Naya, Juan E.; Odom, James L.; Singh, S.; Stahle, Carl M.; Tueller, Jack; Teegarden, Bonnard J.

    1996-10-01

    Because of its high atomic number and convenient room temperature operation, CdZnTe has great potential for use in both balloon and space borne hard x-ray (5 - 200 keV) astrophysics experiments. Here we present preliminary results from the first CdZnTe background measurements made by a balloon instrument. Measurements of the CdZnTe internal background are essential to determine which physical processes make the most important background contributions and are critical in the design of future scientific instruments. The PoRTIA CdZnTe balloon instrument was flown three times in three different shielding configurations. PoRTIA was passively shielded during its first flight from Palestine, Texas and actively shielded as a piggyback instrument on the GRIS balloon experiment during flights 2 and 3 from Alice Springs, Australia. PoRTIA flew twice during the Fall 1995 Alice Springs, Australia campaign using the thick GRIS NaI anticoincidence shield. A significant CdZnTe background reduction was achieved during the third flight with PoRTIA placed completely inside the GRIS shield and blocking crystal, and thus completely surrounded by 15 cm of NaI. These background results are presented and contributions from different background processes are discussed.

  18. Mechanism for radiative recombination in ZnCdO alloys

    SciTech Connect

    Buyanova, I. A.; Bergman, J. P.; Pozina, G.; Chen, W. M.; Rawal, S.; Norton, D. P.; Pearton, S. J.; Osinsky, A.; Dong, J. W.

    2007-06-25

    Temperature dependent cw- and time-resolved photoluminescence combined with absorption measurements are employed to evaluate the origin of radiative recombination in ZnCdO alloys grown by molecular-beam epitaxy. The near-band-edge emission is attributed to recombination of excitons localized within band tail states likely caused by nonuniformity in Cd distribution. Energy transfer between the tail states is argued to occur via tunneling of localized excitons. The transfer is shown to be facilitated by increasing Cd content due to a reduction of the exciton binding energy and, therefore, an increase of the exciton Bohr radius in the alloys with a high Cd content.

  19. CdZnTe photodiode arrays for medical imaging

    SciTech Connect

    Sudharsanan, R.; Parodos, T.; Karam, N.H.; Ruzin, A.; Nemirovsky, Y.

    1996-08-01

    In this paper, we report on the design, fabrication, and performance of the first CdZnTe Schottky photodiode arrays for radiation detection. High pressure Bridgman-grown CdZnTe substrates with bulk resistivities in the range 10{sup 8} to 10{sup 10} ohm-cm were used. CdZnTe Schottky photodiodes were formed with In and Ti/Au contacts. Diode arrays with pixel sizes from 1000 x 1000 {mu}m to 100 x 100 {mu}m were fabricated. The diode`s I-V characteristics exhibited low leakage current and high bulk resistivity; leakage current decreased as diode pixel size was reduced. Response of these detector arrays to high energy photons was uniform and their energy resolution improved with smaller pixel size. 14 refs., 9 figs.

  20. Heat-induced transformation of CdSe-CdS-ZnS core-multishell quantum dots by Zn diffusion into inner layers.

    PubMed

    Yalcin, Anil O; Goris, Bart; van Dijk-Moes, Relinde J A; Fan, Zhaochuan; Erdamar, Ahmet K; Tichelaar, Frans D; Vlugt, Thijs J H; Van Tendeloo, Gustaaf; Bals, Sara; Vanmaekelbergh, Daniël; Zandbergen, Henny W; van Huis, Marijn A

    2015-02-25

    In this work, we investigate the thermal evolution of CdSe-CdS-ZnS core-multishell quantum dots (QDs) in situ using transmission electron microscopy (TEM). Starting at a temperature of approximately 250 °C, Zn diffusion into inner layers takes place together with simultaneous evaporation of particularly Cd and S. As a result of this transformation, CdxZn1-xSe-CdyZn1-yS core-shell QDs are obtained.

  1. Use of microbial community to evaluate performance of a wetland system in treating Pb/Zn mine drainage.

    PubMed

    Yu, Yu H; Feng, Wei S; Shen, Yun F; Ye, Zhi H; Wong, Ming H

    2005-12-01

    The performance of a wetland system in treating lead (Pb)/zinc (Zn) mine drainage was evaluated by using the polyurethane foam unit (PFU) microbial community (method), which has been adopted by China as a standardized procedure for monitoring water quality. The wetland system consisted of four cells with three dominant plants: Typha latifolia, Phragmites australis and Paspalum distichum. Physicochemical characteristics [pH, EC, content of total suspended solid (TSS) and metals (Pb, Zn, Cd, and Cu)] and PFU microbial community in water samples had been investigated from seven sampling sites. The results indicated that the concentrations of Pb, Zn, Cd, Cu, and TSS in the mine drainage were gradually reduced from the inlet to the outlet of the wetland system and 99%, 98%, 75%, 83%, and 68% of these metals and TSS respectively, had been reduced in concentration after the drainage passed through the wetland system. A total of 105 protozoan species were identified, the number of protozoa species and the diversity index (DI) gradually increased, while the heterotrophic index (HI) gradually decreased from the inlet to the outlet of the wetland system. The results indicated that DI, HI, and total number species of protozoa could be used as biological indicators indicating the improvement of water quality.

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

    NASA Astrophysics Data System (ADS)

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

    2012-06-01

    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.

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

    PubMed

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

    2013-02-15

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

  4. XAFS Determination of Pb and Cd Speciation with Siderophores and the Metal/Siderophore/Kaolinite System

    SciTech Connect

    Mishra, Bhoopesh; Vasconcelos, Igor F.; Bunker, Bruce A.; Haack, Elizabeth A.; Maurice, Patricia A.

    2007-02-02

    We provide evidence for hexadentate complexes of Pb2+ and Cd2+ with the trihydroxamate siderophore desferrioxamine B (DFO-B) at pH 7.5, and 9.0, respectively. Analysis of the species of Pb2+ and Cd2+ adsorbed at the surface of kaolinite clay under the same pH conditions and in the presence of DFO-B indicate that Pb2+ is sorbed as a metal-siderophore complex while Cd2+ is not.

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

    PubMed

    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.

  6. Proteomic Profiling of the Interactions of Cd/Zn in the Roots of Dwarf Polish Wheat (Triticum polonicum L.)

    PubMed Central

    Wang, Yi; Wang, Xiaolu; Wang, Chao; Wang, Ruijiao; Peng, Fan; Xiao, Xue; Zeng, Jian; Fan, Xing; Kang, Houyang; Sha, Lina; Zhang, Haiqin; Zhou, Yonghong

    2016-01-01

    Cd and Zn have been shown to interact antagonistically or synergistically in various plants. In the present study of dwarf polish wheat (DPW)roots, Cd uptake was inhibited by Zn, and Zn uptake was inhibited by Cd, suggesting that Cd and Zn interact antagonistically in this plant. A study of proteomic changes showed that Cd, Zn, and Cd+Zn stresses altered the expression of 206, 303, and 190 proteins respectively. Among these, 53 proteins were altered significantly in response to all these stresses (Cd, Zn, and Cd+Zn), whereas 58, 131, and 47 proteins were altered in response to individual stresses (Cd, Zn, and Cd+Zn, respectively). Sixty-one differentially expressed proteins (DEPs) were induced in response to both Cd and Zn stresses; 33 proteins were induced in response to both Cd and Cd+Zn stresses; and 57 proteins were induced in response to both Zn and Cd+Zn stresses. These results indicate that Cd and Zn induce differential molecular responses, which result in differing interactions of Cd/Zn. A number of proteins that mainly participate in oxidation-reduction and GSH, SAM, and sucrose metabolisms were induced in response to Cd stress, but not Cd+Zn stress. This result indicates that these proteins participate in Zn inhibition of Cd uptake and ultimately cause Zn detoxification of Cd. Meanwhile, a number of proteins that mainly participate in sucrose and organic acid metabolisms and oxidation-reduction were induced in response to Zn stress but not Cd+Zn stress. This result indicates that these proteins participate in Cd inhibition of Zn uptake and ultimately cause the Cd detoxification of Zn. Other proteins induced in response to Cd, Zn, or Cd+Zn stress, participate in ribosome biogenesis, DNA metabolism, and protein folding/modification and may also participate in the differential defense mechanisms.

  7. Proteomic Profiling of the Interactions of Cd/Zn in the Roots of Dwarf Polish Wheat (Triticum polonicum L.).

    PubMed

    Wang, Yi; Wang, Xiaolu; Wang, Chao; Wang, Ruijiao; Peng, Fan; Xiao, Xue; Zeng, Jian; Fan, Xing; Kang, Houyang; Sha, Lina; Zhang, Haiqin; Zhou, Yonghong

    2016-01-01

    Cd and Zn have been shown to interact antagonistically or synergistically in various plants. In the present study of dwarf polish wheat (DPW)roots, Cd uptake was inhibited by Zn, and Zn uptake was inhibited by Cd, suggesting that Cd and Zn interact antagonistically in this plant. A study of proteomic changes showed that Cd, Zn, and Cd+Zn stresses altered the expression of 206, 303, and 190 proteins respectively. Among these, 53 proteins were altered significantly in response to all these stresses (Cd, Zn, and Cd+Zn), whereas 58, 131, and 47 proteins were altered in response to individual stresses (Cd, Zn, and Cd+Zn, respectively). Sixty-one differentially expressed proteins (DEPs) were induced in response to both Cd and Zn stresses; 33 proteins were induced in response to both Cd and Cd+Zn stresses; and 57 proteins were induced in response to both Zn and Cd+Zn stresses. These results indicate that Cd and Zn induce differential molecular responses, which result in differing interactions of Cd/Zn. A number of proteins that mainly participate in oxidation-reduction and GSH, SAM, and sucrose metabolisms were induced in response to Cd stress, but not Cd+Zn stress. This result indicates that these proteins participate in Zn inhibition of Cd uptake and ultimately cause Zn detoxification of Cd. Meanwhile, a number of proteins that mainly participate in sucrose and organic acid metabolisms and oxidation-reduction were induced in response to Zn stress but not Cd+Zn stress. This result indicates that these proteins participate in Cd inhibition of Zn uptake and ultimately cause the Cd detoxification of Zn. Other proteins induced in response to Cd, Zn, or Cd+Zn stress, participate in ribosome biogenesis, DNA metabolism, and protein folding/modification and may also participate in the differential defense mechanisms.

  8. Proteomic Profiling of the Interactions of Cd/Zn in the Roots of Dwarf Polish Wheat (Triticum polonicum L.).

    PubMed

    Wang, Yi; Wang, Xiaolu; Wang, Chao; Wang, Ruijiao; Peng, Fan; Xiao, Xue; Zeng, Jian; Fan, Xing; Kang, Houyang; Sha, Lina; Zhang, Haiqin; Zhou, Yonghong

    2016-01-01

    Cd and Zn have been shown to interact antagonistically or synergistically in various plants. In the present study of dwarf polish wheat (DPW)roots, Cd uptake was inhibited by Zn, and Zn uptake was inhibited by Cd, suggesting that Cd and Zn interact antagonistically in this plant. A study of proteomic changes showed that Cd, Zn, and Cd+Zn stresses altered the expression of 206, 303, and 190 proteins respectively. Among these, 53 proteins were altered significantly in response to all these stresses (Cd, Zn, and Cd+Zn), whereas 58, 131, and 47 proteins were altered in response to individual stresses (Cd, Zn, and Cd+Zn, respectively). Sixty-one differentially expressed proteins (DEPs) were induced in response to both Cd and Zn stresses; 33 proteins were induced in response to both Cd and Cd+Zn stresses; and 57 proteins were induced in response to both Zn and Cd+Zn stresses. These results indicate that Cd and Zn induce differential molecular responses, which result in differing interactions of Cd/Zn. A number of proteins that mainly participate in oxidation-reduction and GSH, SAM, and sucrose metabolisms were induced in response to Cd stress, but not Cd+Zn stress. This result indicates that these proteins participate in Zn inhibition of Cd uptake and ultimately cause Zn detoxification of Cd. Meanwhile, a number of proteins that mainly participate in sucrose and organic acid metabolisms and oxidation-reduction were induced in response to Zn stress but not Cd+Zn stress. This result indicates that these proteins participate in Cd inhibition of Zn uptake and ultimately cause the Cd detoxification of Zn. Other proteins induced in response to Cd, Zn, or Cd+Zn stress, participate in ribosome biogenesis, DNA metabolism, and protein folding/modification and may also participate in the differential defense mechanisms. PMID:27683584

  9. Proteomic Profiling of the Interactions of Cd/Zn in the Roots of Dwarf Polish Wheat (Triticum polonicum L.)

    PubMed Central

    Wang, Yi; Wang, Xiaolu; Wang, Chao; Wang, Ruijiao; Peng, Fan; Xiao, Xue; Zeng, Jian; Fan, Xing; Kang, Houyang; Sha, Lina; Zhang, Haiqin; Zhou, Yonghong

    2016-01-01

    Cd and Zn have been shown to interact antagonistically or synergistically in various plants. In the present study of dwarf polish wheat (DPW)roots, Cd uptake was inhibited by Zn, and Zn uptake was inhibited by Cd, suggesting that Cd and Zn interact antagonistically in this plant. A study of proteomic changes showed that Cd, Zn, and Cd+Zn stresses altered the expression of 206, 303, and 190 proteins respectively. Among these, 53 proteins were altered significantly in response to all these stresses (Cd, Zn, and Cd+Zn), whereas 58, 131, and 47 proteins were altered in response to individual stresses (Cd, Zn, and Cd+Zn, respectively). Sixty-one differentially expressed proteins (DEPs) were induced in response to both Cd and Zn stresses; 33 proteins were induced in response to both Cd and Cd+Zn stresses; and 57 proteins were induced in response to both Zn and Cd+Zn stresses. These results indicate that Cd and Zn induce differential molecular responses, which result in differing interactions of Cd/Zn. A number of proteins that mainly participate in oxidation-reduction and GSH, SAM, and sucrose metabolisms were induced in response to Cd stress, but not Cd+Zn stress. This result indicates that these proteins participate in Zn inhibition of Cd uptake and ultimately cause Zn detoxification of Cd. Meanwhile, a number of proteins that mainly participate in sucrose and organic acid metabolisms and oxidation-reduction were induced in response to Zn stress but not Cd+Zn stress. This result indicates that these proteins participate in Cd inhibition of Zn uptake and ultimately cause the Cd detoxification of Zn. Other proteins induced in response to Cd, Zn, or Cd+Zn stress, participate in ribosome biogenesis, DNA metabolism, and protein folding/modification and may also participate in the differential defense mechanisms. PMID:27683584

  10. Stable and Metastable Equilibria in the Pb-Cd System

    NASA Astrophysics Data System (ADS)

    Chuang, Ying-Yu; Paik, J.-S.; Zhang, C.; Perepezko, J. H.; Chang, Y. A.

    2013-07-01

    Thermodynamic and phase diagram data in the Pb-Cd system are reevaluated. A substitutional solution model is used for the liquid and fcc and hcp phases. The stable and metastable equilibria of this system are calculated using the thermodynamic equations derived from equilibrium data. Besides the well-established eutectic reaction at 521 K (248 °C), one stable monotectic reaction at 548 K (275 °C) is found due to the existence of a stable liquid miscibility gap. The stable monotectic reaction has been missed in all previous evaluations. Experimental verifications of the stable and metastable phase equilibria are provided using droplet samples and undercooled liquid alloys. A differential thermal analysis (DTA) method is applied to determine the phase reaction temperatures using both traditional heating and cooling processes and a specially designed cycling process. Additional microstructural evidence is used to elucidate the nature of the phase reactions. The refined thermodynamic descriptions are based upon both the thermochemical and phase diagram stable and metastable data. The agreement between the calculated and experimental data is good. All experimental stable and metastable results are well explained by the new Pb-Cd phase diagram calculations within the experimental accuracy limits. Combined experimental and thermodynamic modeling procedures developed for determining the stable and metastable phase equilibria yield a highly reliable overall phase diagram assessment and a quantitative basis for the interpretation of non-equilibrium solidification processing.

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

    SciTech Connect

    Chen, Ling; Gong, Haibo; Zheng, Xiaopeng; Zhu, Min; Zhang, Jun; Yang, Shikuan; Cao, Bingqiang

    2013-10-15

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

  13. Sulfidation Roasting of Hemimorphite with Pyrite for the Enrichment of Zn and Pb

    NASA Astrophysics Data System (ADS)

    Min, Xiao-Bo; Xue, Ke; Ke, Yong; Zhou, Bo-Sheng; Li, Yang-Wen-Jun; Wang, Qing-Wei

    2016-06-01

    With the increasing consumption of zinc and the depletion of zinc sulfide ores, the exploitation of low-grade zinc oxide ores may be important for the sustainability of the zinc industry. Hemimorphite, a zinc hydroxyl silicate hydrate, is a significant source of Zn and Pb. It is difficult to obtain Zn and Pb from the hemimorphite using traditional technology. In this work, for the first time, sulfidation roasting of hemimorphite with pyrite was studied for the enrichment of Zn and Pb by a flotation process. Four stages of sulfidation roasting were determined based on x-ray diffraction and thermogravimetry analysis. Then, the effects of sulfidation temperature, pyrite dosage and reaction time on the sulfidation percentages were investigated at the laboratory scale. The experimental results showed that the sulfidation percentages of Pb and Zn were as high as 98.08% and 90.55% under optimum conditions, respectively. Finally, a flotation test was performed to enrich Zn and Pb in the sulfidation product. A flotation concentrate with 8.78% Zn and 9.25% Pb was obtained, and the recovery of Zn and Pb reached 56.14% and 75.94%, respectively.

  14. Sulfidation Roasting of Hemimorphite with Pyrite for the Enrichment of Zn and Pb

    NASA Astrophysics Data System (ADS)

    Min, Xiao-Bo; Xue, Ke; Ke, Yong; Zhou, Bo-Sheng; Li, Yang-Wen-Jun; Wang, Qing-Wei

    2016-09-01

    With the increasing consumption of zinc and the depletion of zinc sulfide ores, the exploitation of low-grade zinc oxide ores may be important for the sustainability of the zinc industry. Hemimorphite, a zinc hydroxyl silicate hydrate, is a significant source of Zn and Pb. It is difficult to obtain Zn and Pb from the hemimorphite using traditional technology. In this work, for the first time, sulfidation roasting of hemimorphite with pyrite was studied for the enrichment of Zn and Pb by a flotation process. Four stages of sulfidation roasting were determined based on x-ray diffraction and thermogravimetry analysis. Then, the effects of sulfidation temperature, pyrite dosage and reaction time on the sulfidation percentages were investigated at the laboratory scale. The experimental results showed that the sulfidation percentages of Pb and Zn were as high as 98.08% and 90.55% under optimum conditions, respectively. Finally, a flotation test was performed to enrich Zn and Pb in the sulfidation product. A flotation concentrate with 8.78% Zn and 9.25% Pb was obtained, and the recovery of Zn and Pb reached 56.14% and 75.94%, respectively.

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

    NASA Astrophysics Data System (ADS)

    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

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

    DOE PAGES

    Cingarapu, Sreeram; Yang, Zhiqiang; Sorensen, Christopher M.; Klabunde, Kenneth J.

    2012-01-01

    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 digestivemore » 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.« less

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

    NASA Astrophysics Data System (ADS)

    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.

  18. Synthesis and characterization of highly-ordered ZnO/PbS core/shell heterostructures

    NASA Astrophysics Data System (ADS)

    Zhu, Y. F.; Zhou, G. H.; Ding, H. Y.; Liu, A. H.; Lin, Y. B.; Dong, Y. W.

    2011-11-01

    The strategy to manipulate nanoscale building blocks into well-organized heterostructures is very important to both material synthesis and nanodevice applications. In this work, highly-ordered ZnO/PbS core/shell nanowire arrays were fabricated by a facile and low temperature chemical route. Large area and well-aligned ZnO nanowire arrays were firstly fabricated on conductive glass substrates, and then the synthesis of ZnO/ZnS and ZnO/PbS core/shell nanowire arrays were realized by a chemical conversion method. The morphology, structure, and composition of the obtained nanostructures were confirmed by field-emission scanning electron microscopy, energy-dispersive X-ray analysis, and X-ray diffraction measurements. The optical properties of the synthesized nanostructures were investigated by micro-Raman and photoluminescence spectroscopy. In the synthesized ZnO/PbS core/shell nanowire arrays, the ZnO cores can provide direct conduction pathways for electron transport and PbS shells possess superior photoelectric performance. Therefore, the obtained ZnO/PbS core/shell nanostructures may have potential application in photovoltaic devices.

  19. Comparison of chelates for enhancing Ricinus communis L. phytoremediation of Cd and Pb contaminated soil.

    PubMed

    Zhang, Hanzhi; Guo, Qingjun; Yang, Junxing; Ma, Jie; Chen, Gang; Chen, Tongbin; Zhu, Guangxu; Wang, Jian; Zhang, Guangxin; Wang, Xin; Shao, Chunyan

    2016-11-01

    We studied chelate effects on castor bean (Ricinus communis L.) growth. These effects included Cd and Pb accumulation in plant tissues and the chemical behavior of Cd and Pb in the plant rhizosphere and non-rhizosphere. Tests were conducted in a glasshouse using the rhizobag method. Two castor bean cultivars (Zibo-3 and Zibo-9) were grown in soil contaminated with 3.53mg/kg Cd and 274mg/kg Pb. The soil was treated with citric acid (CA), ethylenediamine disuccinic acid (EDDS) or ethylenediamine tetraacetic acid (EDTA) (5mmol/kg). EDDS-treated soil produced 28.8% and 59.4% greater biomass for Zibo-3 and Zibo-9 respectively. In contrast, CA and EDTA inhibited the growth of the two cultivars. Zibo-9 had greater tolerance than Zibo-3 to chelate toxicity. Based on Cd and Pb plant uptake, EDDS could substitute for EDTA for phytoremediation of Cd in soil. EDTA was the most effective of the three chelates for Pb phytoremediation but it is less suitable for field use due to toxicology environmental persistence. Acid extractable Cd and Pb in the rhizosphere or reducible Cd and Pb in the non-rhizosphere of soil were the main influences on Cd and Pb accumulation in castor bean. PMID:27414256

  20. Comparison of chelates for enhancing Ricinus communis L. phytoremediation of Cd and Pb contaminated soil.

    PubMed

    Zhang, Hanzhi; Guo, Qingjun; Yang, Junxing; Ma, Jie; Chen, Gang; Chen, Tongbin; Zhu, Guangxu; Wang, Jian; Zhang, Guangxin; Wang, Xin; Shao, Chunyan

    2016-11-01

    We studied chelate effects on castor bean (Ricinus communis L.) growth. These effects included Cd and Pb accumulation in plant tissues and the chemical behavior of Cd and Pb in the plant rhizosphere and non-rhizosphere. Tests were conducted in a glasshouse using the rhizobag method. Two castor bean cultivars (Zibo-3 and Zibo-9) were grown in soil contaminated with 3.53mg/kg Cd and 274mg/kg Pb. The soil was treated with citric acid (CA), ethylenediamine disuccinic acid (EDDS) or ethylenediamine tetraacetic acid (EDTA) (5mmol/kg). EDDS-treated soil produced 28.8% and 59.4% greater biomass for Zibo-3 and Zibo-9 respectively. In contrast, CA and EDTA inhibited the growth of the two cultivars. Zibo-9 had greater tolerance than Zibo-3 to chelate toxicity. Based on Cd and Pb plant uptake, EDDS could substitute for EDTA for phytoremediation of Cd in soil. EDTA was the most effective of the three chelates for Pb phytoremediation but it is less suitable for field use due to toxicology environmental persistence. Acid extractable Cd and Pb in the rhizosphere or reducible Cd and Pb in the non-rhizosphere of soil were the main influences on Cd and Pb accumulation in castor bean.

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

    SciTech Connect

    Zubiaga, A.; Reurings, F.; Tuomisto, F.; Plazaola, F.; Kuznetsov, A. Yu.; Egger, W.; Zuniga-Perez, J.; Munoz-Sanjose, V.

    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.

  2. Pb and Cd Contents in Soil, Water, and Trees at an Afforestation Site, South China.

    PubMed

    Pei, Nancai; Chen, Bufeng; Liu, Shuguang

    2015-11-01

    Pb and Cd contents in 13 plantation tree species (leaf and branch components), soil, water (groundwater and river water) at a young (3-5 year-old) seashore afforestation stand were investigated in Nansha district, Guangzhou city in southern China. The results showed that (1) soil, rather than water or trees, had the highest content of both Pb (averagely 48.79 mg/kg) and Cd (0.50 mg/kg), demonstrating that soil might function as a major reservoir for extraneously derived heavy metals; (2) Pb content was higher in branches than in leaves, but Cd content appeared similar in both components, implying possibly different accumulation mechanisms in trees; (3) Pb and Cd appeared to accumulate differently among some tree taxa, whereas almost no significant difference was detected between introduced and indigenous species. The study indicated that trees were potentially useful to remediate sites contaminated with Pb and Cd in the urbanized areas. PMID:26242803

  3. Pb and Cd Contents in Soil, Water, and Trees at an Afforestation Site, South China.

    PubMed

    Pei, Nancai; Chen, Bufeng; Liu, Shuguang

    2015-11-01

    Pb and Cd contents in 13 plantation tree species (leaf and branch components), soil, water (groundwater and river water) at a young (3-5 year-old) seashore afforestation stand were investigated in Nansha district, Guangzhou city in southern China. The results showed that (1) soil, rather than water or trees, had the highest content of both Pb (averagely 48.79 mg/kg) and Cd (0.50 mg/kg), demonstrating that soil might function as a major reservoir for extraneously derived heavy metals; (2) Pb content was higher in branches than in leaves, but Cd content appeared similar in both components, implying possibly different accumulation mechanisms in trees; (3) Pb and Cd appeared to accumulate differently among some tree taxa, whereas almost no significant difference was detected between introduced and indigenous species. The study indicated that trees were potentially useful to remediate sites contaminated with Pb and Cd in the urbanized areas.

  4. Genesis of the Bangbule Pb-Zn-Cu polymetallic deposit in Tibet, western China: Evidence from zircon U-Pb geochronology and S-Pb isotopes

    NASA Astrophysics Data System (ADS)

    Kan, Tian; Zheng, Youye; Gao, Shunbao

    2016-04-01

    The Banbule Pb-Zn-Cu skarn deposit is located in the Longger-Gongbujiangda volcanic magma arc in the Gangdese-Nyainqentanglha Plate. It is the only lead-zinc polymetallic deposit discovered in the westernmost Nyainqentanglha metallogenic belt. The measured and indicated resources include 0.9 Mt of Pb+Zn (4.77% Pb and 4.74% Zn, respectively), 6499 t of Cu, and 178 t of Ag (18.75g/t Ag). The orebodies mainly occur as lenses, veins and irregular shapes in the contact zone between the quartz-porphyry and limestone of the Upper Permian Xiala Formation, or in the boundaries between limestone and sandstone. Pb-Zn-Cu mineralization in the Banbule deposit is closely associated with skarns. The ore minerals are dominated by galena, sphalerite, chalcopyrite, bornite, and magnetite, with subordinate pyrite, malachite, and azurite. The gangue minerals are mainly garnet, actinolite, diopside, quartz, and calcite. The ore-related quartz-porphyry displays LA-ICP-MS zircon U-Pb age of 77.31±0.74 Ma. The δ34S values of sulfides define a narrow range of -0.8 to 4.7‰ indicating a magmatic source for the ore-forming materials. Lead isotopic systematics yield 206Pb/204Pb of 18.698 to 18.752, 207Pb/204Pb of 15.696 to 15.760, and 208Pb/204Pb of 39.097 to 39.320. The data points are constrained around the growth curves of upper crust and orogenic belt according to the tectonic discrimination diagrams. The calculated Δβ - Δγ values plot within the magmatic field according to the discrimination diagram of Zhu et al. (1995). The S-Pb isotopic data suggest that Bangbule is a typical skarn deposit, and the Pb-Zn-Cu mineralization is genetically related to the quartz-porphyry in the mining district. The discovery of the Bangbule deposit indicates that there is metallogenic potential in the westernmost Nyainqentanglha belt, which is of great importance for the exploration work in this area.

  5. Genesis of the Bangbule Pb-Zn-Cu polymetallic deposit in Tibet, western China: Evidence from zircon U-Pb geochronology and S-Pb isotopes

    NASA Astrophysics Data System (ADS)

    Kan, Tian; Zheng, Youye; Gao, Shunbao

    2016-04-01

    The Banbule Pb-Zn-Cu skarn deposit is located in the Longger-Gongbujiangda volcanic magma arc in the Gangdese-Nyainqentanglha Plate. It is the only lead-zinc polymetallic deposit discovered in the westernmost Nyainqentanglha metallogenic belt. The measured and indicated resources include 0.9 Mt of Pb+Zn (4.77% Pb and 4.74% Zn, respectively), 6499 t of Cu, and 178 t of Ag (18.75g/t Ag). The orebodies mainly occur as lenses, veins and irregular shapes in the contact zone between the quartz-porphyry and limestone of the Upper Permian Xiala Formation, or in the boundaries between limestone and sandstone. Pb-Zn-Cu mineralization in the Banbule deposit is closely associated with skarns. The ore minerals are dominated by galena, sphalerite, chalcopyrite, bornite, and magnetite, with subordinate pyrite, malachite, and azurite. The gangue minerals are mainly garnet, actinolite, diopside, quartz, and calcite. The ore-related quartz-porphyry displays LA-ICP-MS zircon U-Pb age of 77.31±0.74 Ma. The δ34S values of sulfides define a narrow range of -0.8 to 4.7‰ indicating a magmatic source for the ore-forming materials. Lead isotopic systematics yield 206Pb/204Pb of 18.698 to 18.752, 207Pb/204Pb of 15.696 to 15.760, and 208Pb/204Pb of 39.097 to 39.320. The data points are constrained around the growth curves of upper crust and orogenic belt according to the tectonic discrimination diagrams. The calculated Δβ ‑ Δγ values plot within the magmatic field according to the discrimination diagram of Zhu et al. (1995). The S-Pb isotopic data suggest that Bangbule is a typical skarn deposit, and the Pb-Zn-Cu mineralization is genetically related to the quartz-porphyry in the mining district. The discovery of the Bangbule deposit indicates that there is metallogenic potential in the westernmost Nyainqentanglha belt, which is of great importance for the exploration work in this area.

  6. A photoelectrochemical biosensor for fibroblast-like synoviocyte cell using visible light-activated NCQDs sensitized-ZnO/CH3NH3PbI3 heterojunction.

    PubMed

    Pang, Xuehui; Zhang, Yong; Pan, Jihong; Zhao, Yanxia; Chen, Yao; Ren, Xiang; Ma, Hongmin; Wei, Qin; Du, Bin

    2016-03-15

    Based on ZnO nanorods (NRs)/CH3NH3PbI3/nitrogen-doped carbon quantum dots (NCQDs) nanocomposites, the highly sensitive detection of fibroblast-like synoviocyte (FLS) cell was realized by a photoelectrochemical (PEC) biosensor. ZnO/CH3NH3PbI3/NCQDs nanocomposites were exploited as the photo-to-electron generator to produce the signal. CH3NH3PbI3 was spin-coated on ZnO surface after ZnO NRs grew on ITO electrode then by dropping on the modified electrode, NCQDs were diffused and adhered to the surface of ZnO and CH3NH3PbI3. In the presence of EDC/NHS, the combination of CH3NH3PbI3 and NCQDs was achieved by the carboxyl groups (-COOH) and amino groups (-NH2) in the preparation process. Furthermore, the capture probe of FLS cell, CD95 antibody, can be anchored by -COOH and -NH2 groups through EDC/NHS. The specific recognition between the antibody capture probes and cell targets gained high-sensitive detection for FLS cell for the first time. The developed biosensor showed a wide linear range from 1.0 × 10(4)cell/mL to 10 cell/mL and a low detection limit of 2 cell/mL. This kind of biosensor would provide a novel detection strategy for FLS cell.

  7. 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

    USGS Publications Warehouse

    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.

  8. Accumulation of Zn, Cu and Cd by crabs and barnacles

    NASA Astrophysics Data System (ADS)

    Rainbow, P. S.

    1985-11-01

    The crab Carcinus maenas (L.) and the barnacle Elminius modestus Darwin were exposed to a range of dissolved concentrations of Zn, Cu and Cd for 21 days in artificial seawater. Accumulation of Zn and Cu by crabs has been interpreted in terms of the presence of a regulation mechanism to maintain constant body concentrations (83·2 ± 19·4 μg Zn g -1 dry wt.; 39·8 ± 9·8 μg Cu g -1 dry wt.) under varying external dissolved metal levels, until a threshold dissolved metal concentration ( c. 400 μg Zn l -1; c. 170 μg Cu l -1) beyond which net accumulation of metal begins. Cadium appears to be accumulated by C. maenas at all exposures with no evidence for regulation of body cadmium concentrations. Exposure of E. modestus to Zn, Cu or Cd caused net accumulation of the respective metal in the bodies of the barnacles, with no evidence for regulation of body metal concentrations.

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

    NASA Astrophysics Data System (ADS)

    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.

  10. CdZnTe arrays for nuclear medicine imaging

    SciTech Connect

    Barber, H.B.

    1996-12-31

    In nuclear medicine, a gamma-ray-emitting radiotracer is injected into the body, and the resulting biodistribution is imaged using a gamma camera. Current gamma cameras use a design developed by Anger. An Anger camera makes use of a slab of scintillation detector that is viewed by an array of photomultiplier tubes and uses an analog position estimation technique to determine the position of the gamma ray`s interaction. The image-forming optics is usually a multi-bore collimator made of lead. Such cameras are characterized by poor, system spatial resolution ({approximately}1 cm) due to poor detector resolution ({approximately}0.4 cm) and poor collimator performance. Arrays of semiconductor detectors are an attractive alternative to scintillators for use in gamma cameras. Semiconductor detectors have excellent energy resolution. High spatial resolution is also possible because large semiconductor detector arrays with small pixel sizes can be produced using photolithography techniques. A new crystal growth technique (high-pressure vertical Bridgman) allows production of detector grade CdTe and CdZnTe in multikilogram ingots. Although the cost of CdZnTe detectors has come down substantially in the last few years, in part because of economies of scale, costs are still more than an order of magnitude higher than those required for a commercial camera ($20--$50/gram). High detector costs are perhaps the major stumbling block to developing a semiconductor gamma camera. The photolithography techniques required to make large CdZnTe arrays have already been demonstrated. This paper discusses the recent developments made in CdZnTe detectors.

  11. Sediment-hosted Pb-Zn Deposits: a global perspective

    USGS Publications Warehouse

    Leach, David L.; Sangster, Donald F.; Kelley, Karen D.; Large, R; Garven, G.; Allen, Craig R.

    2005-01-01

    Sediment-hosted Pb-Zn deposits contain the world's greatest lead and zinc resources and dominate world production of these metals. They are a chverse group of ore deposits hosted by a wide variety of carbonate and siliciclastic roch that have no obviolls genetic association with igneous activity. A nmge of ore-fortl1ing processes in a vmiety of geologic and tectonic environments created these deposits over at least two billion years of Earth history. The metals were precipitated by basinal brines in synsedimentary and early diagenetic to low-grade metamorphic environments. The deposits display a broad range of relationships to enclosing host rocks that includes stratiform, strata-bound, and discordant ores. These ores are divided into two broad subt)1Jes: Mississippi Valley-type (MVT) and sedimentmy exhalative (SEDEX), Despite the "exhalative" component inherent in the term "SEDEX," in this manusclipt, direct evidence of an exhalite in the ore or alteration component is not essential for a deposit to be classified as SEDEX. The presence of laminated sulfides parallel to bedding is assumed to be permissive evidence for exhalative ores. The chstinction between some SEDEX and MVT depOSits can be quite subjective because some SEDEX ores replaced carbonate, whereas some MVT depOSits formed in an early diagenetic environment and display laminated ore textures. Geologic and resource information are presented for 248 depositS that provide a framework to describe ,mel compare these deposits. Nine of tlle 10 largest sediment-hosted Pb-Zn deposits are SEDEX, Of the deposits that contain at least 2.5 million metric tons (Mt), there are 35 SEDEX (excluding Broken Hill-type) deposits and 15 MVT (excluding Iris-type) deposits. Despite the skewed distribution of the deposit size, the two deposits types have an excellent correlation between total tonnage and tonnage of contained metal (Pb + Zn), with a fairly consistent ratio of about lO/l, regardless of the size of the deposit or

  12. Increase of glutathione in mine population of Sedum alfredii: a Zn hyperaccumulator and Pb accumulator.

    PubMed

    Sun, Q; Ye, Z H; Wang, X R; Wong, M H

    2005-11-01

    Phytochelatins (PCs) have been induced in a large range of plant species, but their role in heavy metal tolerance is unclear. Sedum alfredii is a new zinc (Zn) hyperaccumulator and lead (Pb) accumulator found in an old Pb/Zn mine in the Zhejiang Province of China. Until now, the mechanisms of its hyperaccumulation/accumulation and tolerance were poorly understood. The aim of this work was to investigate whether PCs were differentially produced in mine populations of S. alfredii compared with a non-mine control of the same species. The results showed that plants from the mine site were more tolerant to increasing Zn and Pb concentrations than those from the control site. No PCs and cysteine (Cys) were detected by pre-column derivatization with HPLC fluorescence in any tissues of two populations at any treatment, which in turn indicated they were not responsible for Zn and Pb tolerance in the mine population. Instead, Zn and Pb treatments resulted in the increase of glutathione (GSH) for both populations in a tissue-dependent manner. Significant increases were observed in leaf, stem and root tissues of plants grown on the mine site. The results suggest that GSH, rather man PCs, may be involved in Zn and Pb transport, hyperaccumulation/accumulation and tolerance in mine population of S. alfredii. PMID:16225897

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

    PubMed

    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 < 0.05). Furnace slag and M. sinensis reduced CaCl2-extractable heavy metals by 56-91%, red mud and 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. PMID:24681360

  14. Forest Gaps Inhibit Foliar Litter Pb and Cd Release in Winter and Inhibit Pb and Cd Accumulation in Growing Season in an Alpine Forest

    PubMed Central

    He, Jie; Yang, Wanqin; Li, Han; Xu, Liya; Ni, Xiangyin; Tan, Bo; Zhao, Yeyi; Wu, Fuzhong

    2015-01-01

    Aims The release of heavy metals (such as Pb and Cd) from foliar litter play an important role in element cycling in alpine forest ecosystems. Although natural forest gaps could play important roles in the release of heavy metals from foliar litter by affecting the snow cover during the winter and solar irradiation during the growing season, few studies have examined these potential roles. The objectives of this study were to document changes in Pb and Cd dynamics during litter decomposition in the center of gaps and under closed canopies and to investigate the factors that controlled these changes during the winter and growing seasons. Methods Senesced foliar litter from six dominant species, including Kangding willow (Salix paraplesia), Masters larch (Larix mastersiana), Mingjiang fir (Abies faxoniana), Alpine azalea (Rhododendron lapponicum), Red birch (Betula albosinensis) and Mourning cypress (Sabina saltuaria), was placed in litterbags and incubated between the gap center and closed canopy conditions in an alpine forest in the eastern region of the Tibetan Plateau. The litterbags were sampled at the snow formation stage, snow coverage stage, snow melt stage and during the growing season. The Pb and Cd concentrations in the sampled foliar litter were determined by acid digestion (HNO3/HClO4). Important findings Over one year of decomposition, Pb accumulation and Cd release from the foliar litter occurred, regardless of the foliar litter species. However, Pb and Cd were both released from the foliar litter during the winter and accumulated during the growing season. Compared with the gap center and the canopy gap edge, the extended gap edge and the closed canopy showed higher Pb and Cd release rates in winter and higher Pb and Cd accumulation rates during the growing season, respectively. Statistical analyses indicate that the dynamics of Pb were significantly influenced by frequent freeze–thaw cycles in winter and appropriate hydrothermal conditions during

  15. Thiolated DAB dendrimers and CdSe quantum dots nanocomposites for Cd(II) or Pb(II) sensing.

    PubMed

    Algarra, M; Campos, B B; Alonso, B; Miranda, M S; Martínez, A M; Casado, C M; Esteves da Silva, J C G

    2012-01-15

    Four different generation of thiol-DAB dendrimers were synthesized, S-DAB-G(x) (x=1, 2, 3 and 5), and coupled with CdSe quantum dots, to obtain fluorescent nanocomposites as metal ions sensing. Cd(II) and Pb(II) showed the higher enhancement and quenching effects respectively towards the fluorescence of S-DAB-G(5)-CdSe nanocomposite. The fluorescence enhancement provoked by Cd(II) can be linearized using a Henderson-Hasselbalch type equation and the quenching provoked by Pb(II) can be linearized by a Stern-Volmer equation. The sensor responds to Cd(II) ion in the 0.05-0.7μM concentration range and to Pb(II) ion in the 0.01-0.15mM concentration range with a LOD of 0.06mM. The sensor has selectivity limitations but its dendrimer configuration has analytical advantages.

  16. CdZnTe solid-state gamma cameras

    SciTech Connect

    Butler, J.F.; Lingren, C.L.; Friesenhahn, S.J.

    1998-06-01

    The authors report the development of a CdZnTe gamma ray imager whose advantages over the conventional Anger camera include (1) improved contrast resulting from superior energy resolution and unambiguous position determination and (2) the small size and weight and high reliability inherent in an all-solid-state construction. It provides high energy resolution and peak efficiency by incorporating Digirad`s new SpectrumPlus{trademark} detector technology. The new imager employs a modular design, in which each 1 inch x 1 inch module incorporates a monolithic 64-element CdZnTe detector array and ASIC-based circuitry that provides signal conditioning for every channel, identification of valid events and addressing functions. Imagers with a wide range of sizes and shapes can be assembled by tiling modules together on a specially designed signal routing board.

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

    PubMed

    Kubota, Hiroshi; Takenaka, Chisato

    2003-01-01

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

  18. Point Defect Characterization in CdZnTe

    SciTech Connect

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

    2009-03-24

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

  19. Interplay Between Expression of Sulfur Assimilation Pathway Genes and Zn(2+) and Pb(2+) Stress in Acidithiobacillus ferrooxidans.

    PubMed

    Zheng, Chunli; Chen, Minjie; Wang, Dan; Zhang, Li; Wang, JianYing; Zhang, Xuefeng

    2016-10-01

    We have previously demonstrated that in Acidithiobacillus ferrooxidans, resistance to the highly toxic divalent cation Cd(2+) is mediated in part by the sulfur assimilation pathway (SAP) and enhanced intracellular concentrations of cysteine and glutathione(GSH) (Zheng et al., Extremophiles 19:429-436, 2015). In this paper, we investigate the interplay between Zn(2+) and Pb(2+) resistances, SAP gene expression, and thiol-containing metabolite levels. Cells grown in the presence of 300 mM Zn(2+) had enhanced activities of the following enzymes: adenosylphosphosulphate reductase (APR, 40-fold), serine acetyltransferase (SAT, 180-fold), and O-acetylserine (thiol) lyase (OAS-TL, 230-fold). We investigated the concentrations of mRNA transcripts of the genes encoding these enzymes in cells grown in the presence of 600 mM Zn(2+): transcripts for 4 SAP genes-ATPS(ATP sulphurylase), APR, SiR(sulfite reductase), SAT, and OAS-TL-each showed a more than three-fold increase in concentration. At the metabolite level, concentrations of intracellular cysteine and glutathione (GSH) were nearly doubled. When cells were grown in the presence of 10 mM Pb(2+), SAP gene transcript concentrations, cysteine, and GSH concentrations were all decreased, as were SAP enzyme activities. These results suggested that Zn(2+) induced SAP pathway gene transcription, while Pb(2+) inhibited SAP gene expression and enzyme activities compared to the pathway in most organisms. Because of the detoxification function of thiol pool, the results also suggested that the high resistance of A. ferrooxidans to Zn(2+) may also be due to regulation of GSH and the cysteine synthesis pathway. PMID:27376536

  20. Effect of ZnTe and CdZnTe Alloys at the Back Contact of 1-μm-Thick CdTe Thin Film Solar Cells

    NASA Astrophysics Data System (ADS)

    Amin, Nowshad; Yamada, Akira; Konagai, Makoto

    2002-05-01

    N2-doped ZnTe was introduced onto 1-μm-thick CdTe absorbers in order to reduce the carrier recombination at the back contact of CdS/CdTe/C/Ag configuration solar cells. ZnTe films were grown by molecular beam epitaxy (MBE) on GaAs and Corning glass substrates to investigate the characteristics of the films. Epitaxial growth of ZnTe was realized on GaAs substrates and a hole concentration of 8 × 1018 cm-3 with a resistivity of 0.045 Ω \\cdotcm was achieved as a result of nitrogen doping. In contrast, polycrystalline ZnTe films were grown on Corning glass and CdTe thin films. Dark and photoconductivity of ZnTe films increased to 1.43 × 10-5 S/cm and 1.41 × 10-4 S/cm, respectively, while the Zn to Te ratio was decreased to 0.25 during MBE growth. These ZnTe films with different thicknesses were inserted into close-spaced sublimation (CSS)-grown 1-μm-thick CdTe solar cells. A conversion efficiency of 8.31% (Voc: 0.74 V, Jsc: 22.98 mA/cm2, FF: 0.49, area: 0.5 cm2) was achieved for a 0.2-μm-thick ZnTe layer with a cell configuration of CdS/CdTe/ZnTe/Cu-doped-C/Ag. Furthermore, to overcome the problem of possible recombination loss in the interface layer of CdTe and ZnTe, the intermediate ternary CdZnTe is investigated. The compositional factor in Cd1-xZnxTe:N alloy is varied and the dependence of the conductivity is evaluated. For instance, Cd0.5Zn0.5Te:N, with dark and photoconductivity of 2.13 × 10-6 and 2.9 × 10-5 S/cm, respectively, is inserted at the back contact of a 1-μm-thick CdTe solar cell. A conversion efficiency of 7.46% (Voc: 0.68 V, Jsc: 22.60 mA/cm2, FF: 0.49, area: 0.086 cm2) was achieved as the primary result for a 0.2-μm-thick Cd0.5Zn0.5Te:N layer with the cell configuration of CdS/CdTe/Cd0.5Zn0.5Te:N/Au.

  1. Growth responses of three ornamental plants to Cd and Cd-Pb stress and their metal accumulation characteristics.

    PubMed

    Liu, Jia-nv; Zhou, Qi-xing; Sun, Ting; Ma, Lena Q; Wang, Song

    2008-02-28

    Up to now, there was no document on ornamental plants that had been applied to phytoremediation, which can remedy contaminated environment and beautify it at the same time. Thus, the growth responses and possible phytoremediation ability of three ornamental plants selected from the previous preliminary experiments were further examined under single Cd or combined Cd-Pb stress. The results showed that these tested plants had higher tolerance to Cd and Pb contamination and could effectively accumulate the metals, especially for Calendula officinalis and Althaea rosea. For C. officinalis, it grew normally in soils containing 100 mg kg(-1) Cd without suffering phytotoxicity, and the Cd concentration in the roots was up to 1084 mg kg(-1) while the Cd concentration in the shoots was 284 mg kg(-1). For A. rosea, the Cd accumulation in the shoots was higher than that in the roots when the Cd concentration in soils was <100 mg kg(-1), and reached 100 mg kg(-1) as the criteria of a Cd hyperaccumulator when the Cd concentration in soils was 100 mg kg(-1). Their accumulation and tolerance to Cd and Pb were further demonstrated through the hydroponic-culture method. And A. rosea had a great potential as a possible Cd hyperaccumulator under favorable or induced conditions. Furthermore, the interactive effects of Cd and Pb in the three ornamentals were complicated, not only additive, antagonistic or synergistic, but also related to many factors including concentration combinations of heavy metals, plant species and various parts of plants. Thus, it can be forecasted that this work will provide a new way for phytoremediation of contaminated soils.

  2. Incorporation of V, Zn and Pb into the crystalline phases of Portland clinker

    SciTech Connect

    Andrade, F.R.D.; Maringolo, V.; Kihara, Y

    2003-01-01

    Burning of industrial wastes in cement kilns has an increasing environmental importance, brought about by the incorporation of potentially hazardous elements into clinker crystalline phases and partial substitution of primary fuel and raw materials. In this study, experimental clinkers were synthesized, with the addition of V, Zn and Pb to a standard raw meal, from which a control clinker was obtained for comparison. The three metals were chosen as they are present in the alternative fuel petcoke (V) and in industrial wastes (Zn, Pb) commonly burned in cement kilns. Electron microprobe and scanning electron microscope analysis revealed the preferential partition of these metals among the clinker crystalline phases. It was observed that V has shown a preferential partition towards C{sub 2}S. Zn appears in higher amounts in periclase, and C{sub 3}S has higher Zn contents than C{sub 2}S. Pb concentrates in minute spherules and partitions toward C{sub 3}S in small amounts.

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

    NASA Technical Reports Server (NTRS)

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

    2008-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2011-05-01

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

  5. Growth and characterization of Cd1-xZnxTe/ZnO heterostructures from furnace-annealed CdTe/Zn multi-stacks

    NASA Astrophysics Data System (ADS)

    Chakraborty, Monisha; Bhattacharyya, Sugata

    2015-10-01

    Cd1-xZnxTe/ZnO hetero-structures were grown on glass substrates by furnace annealing of stack-deposited CdTe/Zn/CdTe/Zn thin film multi-layers in air. The multilayered structures were annealed in furnace at various temperatures in between 350 and 600 °C. XRD results revealed that while growth of Cd1-xZnxTe compound reached saturation by 500 °C, ZnO growth geared up in between 550 and 600 °C. The band-gap values of the composite structures were less than either standard Cd1-xZnxTe or ZnO. It was because of large presence of free Zn and Cd and staggered type-II band alignment. An exponential growth was observed for the Cd1-xZnxTe particle sizes against annealing temperature. Next SEM images showed reduced surface granularity with increasing Zn percentage in Cd1-xZnxTe. SEM micrographs further revealed growth of fiber like formations of ZnO on film surface with increasing annealing temperature. ImageJ software was further used to analyse the SEM micrographs and compositional characteristics from EDX results were co-related with structural, optical and morphological results.

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

    PubMed Central

    Al-Qunaibit, M. H.

    2009-01-01

    Dead dried Chlorella vulgaris was studied in terms of its performance in binding divalent copper, cadmium, and lead ions from their aqueous or 50% v/v methanol, ethanol, and acetone solutions. The percentage uptake of cadmium ions exhibited a general decrease with decrease in dielectric constant values, while that of copper and lead ions showed a general decrease with increase in donor numbers. Uptake percentage becomes less sensitive to solvent properties the larger the atomic radius of the biosorbed ion, and uptake of copper was the most affected. FT-IR analyses revealed stability of the biomass in mixed solvents and a shift in vibrations of amide(I) and (II), carboxylate, glucose ring, and metal oxygen upon metal binding in all media. ΔνCOO values (59–69 cm−1) confirmed bidentate metal coordination to carboxylate ligands. The value of νasCOO increased slightly upon Cu, Cd, and Pb biosorption from aqueous solutions indicating lowering of symmetry, while a general decrease was noticed in mixed solvents pointing to the opposite. M–O stretching frequencies increased unexpectedly with increase in atomic mass as a result of solvent effect on the nature of binding sites. Lowering polarity of the solvent permits variations in metal-alga bonds strengths; the smaller the metal ion, the more affected. PMID:19688108

  7. XAFS Determination of Pb and Cd Speciation with Siderophores and the Metal/Siderophore/Kaolinite System

    SciTech Connect

    Mishra, Bhoopesh; Haack, Elizabeth A.; Vasconcelos, Igor F.; Maurice, Patricia A.; Bunker, Bruce A.

    2008-06-16

    We provide evidence for hexadentate complexes of Pb{sup 2+} and Cd{sup 2+} with the trihydroxamate siderophore desferrioxamine B (DFO-B) at pH 7.5, and 9.0, respectively. Analysis of the species of Pb{sup 2+} and Cd{sup 2+} adsorbed at the surface of kaolinite clay under the same pH conditions and in the presence of DFO-B indicate that Pb{sup 2+} is sorbed as a metal-siderophore complex while Cd{sup 2+} is not.

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

    PubMed

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

    2014-08-21

    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.

  9. The Role of Crop Cd Bioavailability in Potential for Transfer of Soil Cd Risk to Humans and Wildlife

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cd is a common contaminant in soils affected by mining and smelting of Zn, Pb, Cu and Ag ores and where biosolids, composts and manures are applied. Zn is usually present at 100-200 times higher concentrations than Cd. Because of this relationship of Cd and Zn in ores and contaminated soils, Zn is...

  10. Effects of the Microbial Siderophore DFO-B on Pb and Cd Speciation in Aqueous Solution

    SciTech Connect

    Mishra, Bhoopesh; Haack, Elizabeth A.; Maurice, Patricia A.; Bunker, Bruce A.

    2009-04-08

    This study investigates the complexation environments of aqueous Pb and Cd in the presence of the trihydroxamate microbial siderophore, desferrioxamine-B (DFO-B) as a function of pH. Complexation of aqueous Pb and Cd with DFO-B was predicted using equilibrium speciation calculation. Synchrotron-based X-ray absorption fine structure (XAFS) spectroscopy at Pb L(III) edge and Cd K edge was used to characterize Pb and Cd-DFO-B complexes at pH values predicted to best represent each of the metal-siderophore complexes. Pb was not found to be complexed measurably by DFO-B at pH 3.0, but was complexed by all three hydroxamate groups to form a totally 'caged' hexadentate structure at pH 7.5-9.0. At the intermediate pH value (pH 4.8), a mixture of Pb-DFOB complexes involving binding of the metal through one and two hydroxamate groups was observed. Cd, on the other hand, remained as hydrated Cd{sup 2+} at pH 5.0, occurred as a mixture of Cd-DFOB and inorganic species at pH 8.0, and was bound by three hydroxamate groups from DFO-B at pH 9.0. Overall, the solution species observed with EXAFS were consistent with those predicted thermodynamically. However, Pb speciation at higher pH values differed from that predicted and suggests that published constants underestimate the binding constant for complexation of Pb with all three hydroxamate groups of the DFO-B ligand. This molecular-level understanding of metal-siderophore solution coordination provides physical evidence for complexes of Pb and Cd with DFO-B, and is an important first step toward understanding processes at the microbial- and/or mineral-water interface in the presence of siderophores.

  11. Pb isotopic constraints on the formation of the Dikulushi Cu-Pb-Zn-Ag mineralisation, Kundelungu Plateau (Democratic Republic of Congo)

    NASA Astrophysics Data System (ADS)

    Haest, Maarten; Schneider, Jens; Cloquet, Christophe; Latruwe, Kris; Vanhaecke, Frank; Muchez, Philippe

    2010-04-01

    Base metal-Ag mineralisation at Dikulushi and in other deposits on the Kundelungu Plateau (Democratic Republic of Congo) developed during two episodes. Subeconomic Cu-Pb-Zn-Fe polysulphide ores were generated during the Lufilian Orogeny (c. 520 Ma ago) in a set of E-W- and NE-SW-oriented faults. Their lead has a relatively unradiogenic and internally inhomogeneous isotopic composition (206Pb/204Pb = 18.07-18.49), most likely generated by mixing of Pb from isotopically heterogeneous clastic sources. These sulphides were remobilised and enriched after the Lufilian Orogeny, along reactivated and newly formed NE-SW-oriented faults into a chalcocite-dominated Cu-Ag mineralisation of high economic interest. The chalcocite samples contain only trace amounts of lead and show mostly radiogenic Pb isotope signatures that fall along a linear trend in the 207Pb/204Pb vs. 206Pb/204Pb diagram (206Pb/204Pb = 18.66-23.65; 207Pb/204Pb = 15.72-16.02). These anomalous characteristics reflect a two-stage evolution involving admixture of both radiogenic lead and uranium during a young fluid event possibly c. 100 Ma ago. The Pb isotope systematics of local host rocks to mineralisation also indicate some comparable young disturbance of their U-Th-Pb systems, related to the same event. They could have provided Pb with sufficiently radiogenic compositions that was added to less radiogenic Pb remobilised from precursor Cu-Pb-Zn-Fe polysulphides, whereas the U most likely originated from external sources. Local metal sources are also suggested by the 208Pb/204Pb-206Pb/204Pb systematics of combined ore and rock lead, which indicate a pronounced and diversified lithological control of the immediate host rocks on the chalcocite-dominated Cu-Ag ores. The Pb isotope systematics of polysulphide mineralisation on the Kundelungu Plateau clearly record a diachronous evolution.

  12. Geologic, geochemical, and isotopic studies of a carbonate- and siliciclastic-hosted Pb-Zn deposit at Lion Hill, Vermont

    USGS Publications Warehouse

    Foley, Nora K.; Clark, Sandra H.B.; Woodruff, Laurel G.; Mosier, Elwin L.

    1995-01-01

    The prospect of an Irish-type sedimentary-exhalative origin for stratabound Pb-Zn deposits of the Paleozoic shelf of North America is of considerable importance to understanding the timing of mineralization relative to platform evolution and for evaluating the mineral resource potential of the region. Our study of the Lion Hill deposit indicates a potential for Irish-type Pb-Zn deposits in platform rocks of western Vermont; however, at Lion Hill they contain enrichments of Pb, Zn, and Cu rather than a Pb, Zn, and Ag association.

  13. Research on Root Responses to Pb and Zn Combined Stress of Carex putuoshan.

    PubMed

    Hu, Yong-Lin; Tan, Jia-Lang; Wang, Cheng-Long; Yang, Zhan-Biao; Yang, Yuan-Xiang; Chen, Zhang; Lin, Li-Jin; Wang, Ying-Jun; Sun, Gang; Zhu, Xue-Mei; Shao, Ji-Rong; Zhou, Mei-Liang

    2016-01-01

    Pb hyper-accumulated Carex putuoshan was taken as experimental material and subjected to combined stress of Pb and Zn. The differential expression of proteins in their roots were analyzed by Proteomic Approach. The protein that was directly involved in the cellular defense under the Pb and Zn combined stress was separated, and expression of those genes was analyzed with Carex Evergold as control. The results were obtained by MALDI-TOF/MS analysis. After applying Pb and Zn combined stress, the expression of 9 protein spots (including 7 different proteins, 2 identical proteins, 1 unknown protein) in Carex putuoshan root was found to be significantly up-regulated. Five proteins were obtained from the 9 proteins related to carbohydrate metabolism, including malate dehydrogenase, glyceraldehyde-3-phosphate dehydrogenase, frutose-1,6-bisphosphate aldolase, enolase, and 6- phosphogluconate dehydrogenase. Two proteins were related to protein biosynthesis, including isoflavone reductase and phytochelatin synthase (PCS). From these proteins, the most important protein is PCS, which is a key enzyme in the synthesis of phytochelatins (PCs) and plays an important role in chelation. It is directly involved in cellular defense under Pb and Zn stress. After Pb and Zn combined stress, the CpPCS in Carex putuoshan was cloned. The full length of cDNA is 1461 bps, and it encodes 486 amino acids with molecular weight of 53.86 kD and pI value of 6.12. Two typical phytochelatin synthase subfamily domains constitute CpPCS protein, which includes three adjacent Cys-Cys elements in the C-terminal region. Phylogenetic analysis of PCS proteins from different species showed that it had the closest relationship with the Oryza sativa and Triticum aestivum. Real-time quantitative PCR analysis indicated that CpPCS and CePCS (Carex Evergold) genes were expressed in the root. The CpPCS and CePCS genes were up-regulated by Pb and Zn treatments. The expression of CpPCS was higher than that of Ce

  14. Research on Root Responses to Pb and Zn Combined Stress of Carex putuoshan.

    PubMed

    Hu, Yong-Lin; Tan, Jia-Lang; Wang, Cheng-Long; Yang, Zhan-Biao; Yang, Yuan-Xiang; Chen, Zhang; Lin, Li-Jin; Wang, Ying-Jun; Sun, Gang; Zhu, Xue-Mei; Shao, Ji-Rong; Zhou, Mei-Liang

    2016-01-01

    Pb hyper-accumulated Carex putuoshan was taken as experimental material and subjected to combined stress of Pb and Zn. The differential expression of proteins in their roots were analyzed by Proteomic Approach. The protein that was directly involved in the cellular defense under the Pb and Zn combined stress was separated, and expression of those genes was analyzed with Carex Evergold as control. The results were obtained by MALDI-TOF/MS analysis. After applying Pb and Zn combined stress, the expression of 9 protein spots (including 7 different proteins, 2 identical proteins, 1 unknown protein) in Carex putuoshan root was found to be significantly up-regulated. Five proteins were obtained from the 9 proteins related to carbohydrate metabolism, including malate dehydrogenase, glyceraldehyde-3-phosphate dehydrogenase, frutose-1,6-bisphosphate aldolase, enolase, and 6- phosphogluconate dehydrogenase. Two proteins were related to protein biosynthesis, including isoflavone reductase and phytochelatin synthase (PCS). From these proteins, the most important protein is PCS, which is a key enzyme in the synthesis of phytochelatins (PCs) and plays an important role in chelation. It is directly involved in cellular defense under Pb and Zn stress. After Pb and Zn combined stress, the CpPCS in Carex putuoshan was cloned. The full length of cDNA is 1461 bps, and it encodes 486 amino acids with molecular weight of 53.86 kD and pI value of 6.12. Two typical phytochelatin synthase subfamily domains constitute CpPCS protein, which includes three adjacent Cys-Cys elements in the C-terminal region. Phylogenetic analysis of PCS proteins from different species showed that it had the closest relationship with the Oryza sativa and Triticum aestivum. Real-time quantitative PCR analysis indicated that CpPCS and CePCS (Carex Evergold) genes were expressed in the root. The CpPCS and CePCS genes were up-regulated by Pb and Zn treatments. The expression of CpPCS was higher than that of Ce

  15. Geochemical behavior of heavy metals in a Zn-Pb-Cu mining area in the State of Mexico (central Mexico).

    PubMed

    Lizárraga-Mendiola, L; González-Sandoval, M R; Durán-Domínguez, M C; Márquez-Herrera, C

    2009-08-01

    The geochemical behavior of zinc, lead and copper from sulfidic tailings in a mine site with potential to generate acidic drainage (pyrite (55%) and sphalerite (2%)) is reported in this paper. The mining area is divided in two zones, considering the topographic location of sampling points with respect to the tailings pile: (a) outer zone, out of the probable influence of acid mine drainage (AMD) pollution, and (b) inner zone, probably influenced by AMD pollution. Maximum total ions concentrations (mg/L) measured in superficial waters found were, in the outer zone: As (0.2), Cd (0.9), Fe (19), Mn (39), Pb (5.02), SO4(2-) (4650), Zn (107.67), and in the inner zone are As (0.1), Cd (0.2), Fe (88), Mn (13), Pb (6), SO4(2-) (4,880), Zn (46). The presence of these ions that exceeding the permissible maximum limits for human consume, could be associated to tailings mineralogy and acid leachates generated in tailings pile.

  16. Synthesis and optical properties of core/shell ternary/ternary CdZnSe/ZnSeS quantum dots

    NASA Astrophysics Data System (ADS)

    Nguyen, Hai Yen; de Marcillac, Willy Daney; Lethiec, Clotilde; Phan, Ngoc Hong; Schwob, Catherine; Maître, Agnès; Nguyen, Quang Liem; Le, Van Vu; Bénalloul, Paul; Coolen, Laurent; Thu Nga, Pham

    2014-07-01

    In this paper we report on the synthesis of ternary/ternary alloyed CdZnSe/ZnSeS core/shell quantum dots (QDs) by embryonic nuclei-induced alloying process. We synthesized CdZnSe core QDs emitting in the spectral range of 530-607 nm with various Cd/Zn ratios, depending on the core synthesis temperature. By shelling ZnSeS on the CdZnSe core QDs, the average luminescence quantum yield is increased by a typical factor of 2 up to 17, which we attribute to the reduction of number of non-emitting QDs. The single-photon emitter micro-photoluminescence study showed that the CdZnSe/ZnSeS core/shell QDs are good single-photon emitters and their blinking properties were improved compared to the CdZnSe core QDs. Quantum yields up to 25% were measured for the core/shell samples, demonstrating the potential for high-quality ternary/ternary QDs fabrication.

  17. Theoretical assessment of phosphate amendments for stabilization of (Pb+Zn) in polluted soil.

    PubMed

    Raicevic, S; Perovic, V; Zouboulis, A I

    2009-05-01

    Contamination of the environment with toxic metals, such as lead (Pb), represents a serious concern for human health. Most of the studies on Pb stabilization were performed using various phosphorus-containing amendments that can reduce Pb mobility and bioavailability by the sorption and precipitation of new, stable pyromorphite-type minerals, presenting very low solubility and bioaccessibility. However, the presence of competing ions, such as zinc (Zn), can reduce stabilization efficacy. The role of chemical composition on the stability of immobilization products of Pb and Zn by the addition of hydroxyapatite (HAP) or fluoroapatite (FAP) has been examined in this paper. In this analysis we used a theoretical criterion which is based on calculation of the ion-ion interaction potential, representing the main term of the cohesive energy of the matrix/pollutant system. It has been demonstrated that the stability of the HAP matrix decreases and that the stability of the FAP matrix increases with the Pb immobilization in the presence of Zn. The results of this analysis point out FAP as an advantageous amendment for the immobilization of Pb in the presence of Zn.

  18. Zn, Cd, S and trace metal bioaccumulation in willow (Salix spp.) cultivars grown hydroponically.

    PubMed

    McBride, M B; Martinez, C E; Kim, B

    2016-12-01

    Willows (Salix spp.) can be used to phytoremediate soils contaminated by Zn and Cd under certain conditions. In this study, the ability of 14 Salix cultivars to concentrate Cd, Zn and S in leaves was measured in hydroponic culture with 10 and 200 µM Cd and Zn, respectively, in the nutrient medium. The cultivars showed a wide range of biomass yields, tolerance to metals, and foliar concentrations of Zn and Cd, with some cultivars accumulating up to 1000 mg kg(-1) Zn, 70 mg kg(-1) Cd and 10,000 mg kg(-1) S with only mild phytotoxicity symptoms attributable to excess Zn. Cultivars with higher foliar Zn concentrations tended to have higher foliar Cd concentrations as well, and competition between Zn and Cd for uptake was observed. Exposure of Salix cultivars to Cd and Zn did not affect foliar concentrations of secondary metabolites such as polyphenols, but trace metal concentrations in leaves were significantly reduced (Fe and Cu) or increased (Mn) by exposure to excess Zn and Cd. Sulfur-XANES spectroscopy showed foliar S to be predominantly in highly oxidized (sulfate plus sulfonate) and reduced (thiol) forms, with oxidized S more prevalent in willows with the highest total S content.

  19. Zn, Cd, S and trace metal bioaccumulation in willow (Salix spp.) cultivars grown hydroponically.

    PubMed

    McBride, M B; Martinez, C E; Kim, B

    2016-12-01

    Willows (Salix spp.) can be used to phytoremediate soils contaminated by Zn and Cd under certain conditions. In this study, the ability of 14 Salix cultivars to concentrate Cd, Zn and S in leaves was measured in hydroponic culture with 10 and 200 µM Cd and Zn, respectively, in the nutrient medium. The cultivars showed a wide range of biomass yields, tolerance to metals, and foliar concentrations of Zn and Cd, with some cultivars accumulating up to 1000 mg kg(-1) Zn, 70 mg kg(-1) Cd and 10,000 mg kg(-1) S with only mild phytotoxicity symptoms attributable to excess Zn. Cultivars with higher foliar Zn concentrations tended to have higher foliar Cd concentrations as well, and competition between Zn and Cd for uptake was observed. Exposure of Salix cultivars to Cd and Zn did not affect foliar concentrations of secondary metabolites such as polyphenols, but trace metal concentrations in leaves were significantly reduced (Fe and Cu) or increased (Mn) by exposure to excess Zn and Cd. Sulfur-XANES spectroscopy showed foliar S to be predominantly in highly oxidized (sulfate plus sulfonate) and reduced (thiol) forms, with oxidized S more prevalent in willows with the highest total S content. PMID:27216699

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

    EPA Science Inventory

    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 ...

  1. EDTA-Decorated Nanostructured ZnO/CdS Thin Films for Oxygen Gas Sensing Applications

    NASA Astrophysics Data System (ADS)

    Arunraja, L.; Thirumoorthy, P.; Karthik, A.; Rajendran, V.; Edwinpaul, L.

    2016-08-01

    ZnO/CdS and ZnO/CdS-EDTA nanostructured thin films were prepared on a glass substrate using spin-coating and used for oxygen gas sensor applications. The structural properties of both ZnO/CdS and ZnO/CdS-EDTA nanostructured composites were comparatively characterized. The nanostructure thin film was found in a hexagonal structure with an average crystallite size reduced from 77 nm to 29 nm due to the influence of the EDTA. The optical absorption, photo luminescence, functional groups and surface morphology of the nanostructured thin films were comprehensively investigated. Oxygen was suitably tailored to verify the sensor response over a concentration range of 10-50 ppm at room temperature. Thus, the sensor studies reveal that the performance, response, and recovery time were enhanced in ZnO/CdS-EDTA nanostructured thin film compared with ZnO/CdS.

  2. Plasmon-Coupled CdSe/ZnS and CdTe/CdS/ZnS Coreshells for Hybrid Light Emitting Devices.

    PubMed

    Rice, Quinton; Hayes, Anderson; Jung, Sungsoo; Wang, Andrew; Cho, Hyoyoung; Kim, Wan-Joong; Abdel-Fattah, Mahmoud; Tabibi, Bagher; Seo, Jaetae

    2016-02-01

    Plasmon-coupled CdSe/ZnS and CdTe/CdS/ZnS coreshells are investigated for their optoelectronic applications because of their high color purity, wide optical tunability, large PL enhancement, and compact and easy integration into electronic devices. The quantum confinement of carriers within quantum dots (QDs) with sizes near the exciton Bohr radius (CdSe ~ 5.8 nm, CdTe ~ 7 nm) exhibits the features of discrete energy states and blue-shift from the bulk bandgap (CdSe ~718 nm, CdTe ~ 863 nm) in the optical spectrum. While the fluorescence from the QDs is attributable to the exciton carrier recombination, large PL enhancement and fast emission time is achieved through plasmon-exciton coupling via the Coulomb interaction. Large PL enhancement of QDs in the vicinity of plasmonic particles was observed and attributed to the reduction of the non-radiative decay rate and large local field enhancement. The large PL enhancement and wide optical tunability along with high color purity from plasmon-coupled QDs enables the realization of hybrid LEDs. PMID:27433706

  3. Bioaccessibility of As, Cd, Cu, Ni, Pb, and Sb in toys and low-cost jewelry.

    PubMed

    Guney, Mert; Zagury, Gerald J

    2014-01-21

    Children can be exposed to toxic elements in toys and jewelry following ingestion. As, Cd, Cu, Ni, Pb, and Sb bioavailability was assessed (n = 24) via the in vitro gastrointestinal protocol (IVG), the physiologically based extraction test (PBET), and the European Toy Safety Standard protocol (EN 71-3), and health risks were characterized. Cd, Cu, Ni, and Pb were mobilized from 19 metallic toys and jewelry (MJ) and one crayon set. Bioaccessible Cd, Ni, or Pb exceeded EU migratable concentration limits in four to six MJ, depending on the protocol. Using two-phase (gastric + intestinal) IVG or PBET might be preferable over EN 71-3 since they better represent gastrointestinal physiology. Bioaccessible and total metal concentrations were different and not always correlated, indicating that bioaccessibility measurement may provide more accurate risk characterization. More information on impacts of multiple factors affecting metals mobilization from toys and jewelry is needed before recommending specific tests. Hazard index (HI) for Cd, Ni, or Pb were >1 for all six MJ exceeding the EU limits. For infants (6-12 mo old), 10 MJ had HI > 1 for Cd, Cu, Ni, or Pb (up to 75 for Cd and 43 for Pb). Research on prolonged exposure to MJ and comprehensive risk characterization for toys and jewelry exposure is recommended.

  4. ZnSe/CdSe Superlattice Nanowires by Catalyst-assisted Molecular Beam Epitaxy

    SciTech Connect

    Karczewski, G.; Dluzewski, P.; Kret, S.; Klopotowski, L.; Wojtowicz, T.

    2007-04-10

    We report on Au catalyst-assisted molecular beam epitaxy growth and properties of pure ZnSe and ZnSe/CdSe superlattice nanowires. In particular, we concentrate our attention on the morphological characterization by transmission and scanning electron microscopy of pure ZnSe NWs and we compare their optical properties with those of ZnSe/CdSe superlattice NWs fabricated at the same technological conditions.

  5. Pb(core)/ZnO(shell) nanowires obtained by microwave-assisted method

    PubMed Central

    2011-01-01

    In this study, Pb-filled ZnO nanowires [Pb(core)/ZnO(shell)] were synthesized by a simple and novel one-step vapor transport and condensation method by microwave-assisted decomposition of zinc ferrite. The synthesis was performed using a conventional oven at 1000 W and 5 min of treatment. After synthesis, a spongy white cotton-like material was obtained in the condensation zone of the reaction system. HRTEM analysis revealed that product consists of a Pb-(core) with (fcc) cubic structure that preferentially grows in the [111] direction and a hexagonal wurtzite ZnO-(Shell) that grows in the [001] direction. Nanowire length was more than 5 μm and a statistical analysis determined that the shell and core diameters were 21.00 ± 3.00 and 4.00 ± 1.00 nm, respectively. Experimental, structural details, and synthesis mechanism are discussed in this study. PMID:21985637

  6. Core-Shell Zn x Cd1- x Se/Zn y Cd1- y Se Quantum Dots for Nonvolatile Memory and Electroluminescent Device Applications

    NASA Astrophysics Data System (ADS)

    Al-Amoody, Fuad; Suarez, Ernesto; Rodriguez, Angel; Heller, E.; Huang, Wenli; Jain, F.

    2011-08-01

    This paper presents a floating quantum dot (QD) gate nonvolatile memory device using high-energy-gap Zn y Cd1- y Se-cladded Zn x Cd1- x Se quantum dots ( y > x) with tunneling layers comprising nearly lattice-matched semiconductors (e.g., ZnS/ZnMgS) on Si channels. Also presented is the fabrication of an electroluminescent (EL) device with embedded cladded ZnCdSe quantum dots. These ZnCdSe quantum dots were embedded between indium tin oxide (ITO) on glass and a top Schottky metal electrode deposited on a thin CsF barrier. These QDs, which were nucleated in a photo-assisted microwave plasma (PMP) metalorganic chemical vapor deposition (MOCVD) reactor, were grown between the source and drain regions on a p-type silicon substrate of the nonvolatile memory device. The composition of QD cladding, which relates to the value of y in Zn y Cd1- y Se, was engineered by the intensity of ultraviolet light, which controlled the incorporation of zinc in ZnCdSe. The QD quality is comparable to those deposited by other methods. Characteristics and modeling of the II-VI quantum dots as well as two diverse types of devices are presented in this paper.

  7. Control of Cd concentrations in a coastal diatom by interactions among free ionic Cd, Zn, and Mn in seawater

    SciTech Connect

    Sunda, W.G.; Huntsman, S.A.

    1998-10-01

    Cadmium and phosphate concentrations in seawater are closely correlated, suggesting that Cd distributions, like those of PO{sub 4}, are controlled by algal uptake and regeneration. But the factors controlling Cd levels in phytoplankton are poorly known. Experiments in metal ion buffer systems with a coastal diatom Thalassiosira pseudonana revealed that cellular Cd:C ratios within the Cd ion concentration ([Cd{sup 2+}]) range in seawater were generally proportional to [Cd{sup 2+}] and inversely related to concentrations of Zn and Mn ions ([Zn{sup 2+}] and [Mn{sup 2+}]) and specific growth rate. The effects of Mn and Zn reflect cellular uptake of Cd by two inducible transport systems: the Mn system whose capacity (V{sub max}) is enhanced at low [Mn{sup 2+}] and a separate system induced at low cellular zinc. At the low [Zn{sup 2+}] of surface oceanic waters ({le}10{sup {minus}11.0} M), Cd uptake is controlled by this latter system and, therefore, is inversely related to ionic zinc levels. However, at the higher [Zn{sup 2+}] range of coastal waters, Cd uptake by this system is strongly suppressed and Cd instead is taken up by the Mn system; as a result it is inversely related to [Mn{sup 2+}] and largely independent of variations in [Zn{sup 2+}]. Because of the suppression of Cd uptake by high [Zn{sup 2+}] and [Mn{sup 2+}] in coastal waters, algal Cd concentrations may be lower in these waters than in the ocean despite the presence of higher coastal [Cd{sup 2+}].

  8. Experimental study of {sup 113}Cd {beta} decay using CdZnTe detectors

    SciTech Connect

    Goessling, C.; Kiel, H.; Muenstermann, D.; Oehl, S.; Junker, M.; Zuber, K.

    2005-12-15

    A search for the fourfold forbidden {beta} decay of {sup 113}Cd has been performed with CdZnTe semiconductors. With 0.86 kg {center_dot} d of statistics a half-life for the decay of T{sub 1/2}=[8.2{+-}0.2(stat.){sub -1.0}{sup +0.2}(sys.)]x10{sup 15} yr has been obtained. This is in good agreement with published values. A comparison of the spectral shape with the one given on the Table of Isotopes Web page shows a severe deviation.

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

    NASA Astrophysics Data System (ADS)

    Williams, B. L.; Taylor, A. A.; Mendis, B. G.; Phillips, L.; Bowen, L.; Major, J. D.; Durose, K.

    2014-02-01

    Radial p-n junction nanowire (NW) solar cells with high densities of CdTe NWs coated with indium tin oxide (ITO)/ZnO/CdS triple shells were grown with excellent heterointerfaces. The optical reflectance of the devices was lower than for equivalent planar films by a factor of 100. The best efficiency for the NW solar cells was η = 2.49%, with current transport being dominated by recombination, and the conversion efficiencies being limited by a back contact barrier (ϕB = 0.52 eV) and low shunt resistances (RSH < 500 Ω.cm2).

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

    PubMed

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

    2014-01-01

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

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

    PubMed

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

    2012-10-01

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

  12. Immobilization of Cu, Pb and Zn in mine-contaminated soils using reactive materials.

    PubMed

    Navarro, Andrés; Cardellach, Esteve; Corbella, Mercé

    2011-02-28

    Immobilization processes were used to chemically stabilize soil contaminated with Cu, Pb and Zn from mine tailings and industrial impoundments. We examined the effectiveness of ordinary Portland cement (OPC), phosphoric acid and MgO at immobilizing Cu, Pb and Zn in soil contaminated by either mine tailings or industrial and mine wastes. The effectiveness was evaluated using column leaching experiments and geochemical modelling, in which we assessed possible mechanisms for metal immobilization using PHREEQC and Medusa numerical codes. Experimental results showed that Cu was mobilized in all the experiments, whereas Pb immobilization with H(3)PO(4) may have been related to the precipitation of chloropyromorphite. Thus, the Pb concentrations of leachates of pure mining and industrial contaminated soils (32-410 μg/l and 430-1000 μg/l, respectively) were reduced to 1-60 and 3-360 μg/l, respectively, in the phosphoric acid experiment. The mobilization of Pb at high alkaline conditions, when Pb(OH)(4)(-) is the most stable species, may be the main obstacle to the use of OPC and MgO in the immobilization of this metal. In the mining- and industry-contaminated soil, Zn was retained by OPC but removed by MgO. The experiments with OPC showed the Zn decrease in the leachates of mining soil from 226-1960 μg/l to 92-121 μg/l. In the industrial contaminated soil, the Zn decrease in the leachates was most elevated, showing >2500 μg/l in the leachates of contaminated soil and 76-173 μg/l in the OPC experiment. Finally, when H(3)PO(4) was added, Zn was mobilized.

  13. Immobilization of Cu, Pb and Zn in mine-contaminated soils using reactive materials.

    PubMed

    Navarro, Andrés; Cardellach, Esteve; Corbella, Mercé

    2011-02-28

    Immobilization processes were used to chemically stabilize soil contaminated with Cu, Pb and Zn from mine tailings and industrial impoundments. We examined the effectiveness of ordinary Portland cement (OPC), phosphoric acid and MgO at immobilizing Cu, Pb and Zn in soil contaminated by either mine tailings or industrial and mine wastes. The effectiveness was evaluated using column leaching experiments and geochemical modelling, in which we assessed possible mechanisms for metal immobilization using PHREEQC and Medusa numerical codes. Experimental results showed that Cu was mobilized in all the experiments, whereas Pb immobilization with H(3)PO(4) may have been related to the precipitation of chloropyromorphite. Thus, the Pb concentrations of leachates of pure mining and industrial contaminated soils (32-410 μg/l and 430-1000 μg/l, respectively) were reduced to 1-60 and 3-360 μg/l, respectively, in the phosphoric acid experiment. The mobilization of Pb at high alkaline conditions, when Pb(OH)(4)(-) is the most stable species, may be the main obstacle to the use of OPC and MgO in the immobilization of this metal. In the mining- and industry-contaminated soil, Zn was retained by OPC but removed by MgO. The experiments with OPC showed the Zn decrease in the leachates of mining soil from 226-1960 μg/l to 92-121 μg/l. In the industrial contaminated soil, the Zn decrease in the leachates was most elevated, showing >2500 μg/l in the leachates of contaminated soil and 76-173 μg/l in the OPC experiment. Finally, when H(3)PO(4) was added, Zn was mobilized. PMID:21190796

  14. Microstructural and optical properties of CdSe/CdS/ZnS core-shell-shell quantum dots.

    PubMed

    Lee, Dea Uk; Kim, Dae Hun; Choi, Dong Hyuk; Kim, Sang Wook; Lee, Hong Seok; Yoo, Keon-Ho; Kim, Tae Whan

    2016-01-25

    CdSe/CdS/ZnS core-shell-shell quantum dots (QDs) were synthesized by using a solution process. High-resolution transmission electron microscopy images and energy dispersive spectroscopy profiles confirmed that stoichiometric CdSe/CdS/ZnS core-shell-shell QDs were formed. Ultraviolet-visible absorption and photoluminescence (PL) spectra of CdSe/CdS/ZnS core-shell-shell QDs showed the dominant excitonic transitions from the ground electronic subband to the ground hole subband (1S(e)-1S(3/2)(h)). The PL mechanism is suggested; the carriers generated by the exciting high-energy photons in the shell region are relaxed to the band-edge states of the core region and recombined to emit lower-energy photons. The activation energy of the carriers confined in the CdSe/CdS/ZnS core-shell-shell QDs, as obtained from temperature-dependent PL spectra, was 200 meV. The quantum efficiency of the CdSe/CdS/ZnS core-shell-shell QDs at 300 K was estimated to be approximately 57%.

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

    PubMed

    van Genuchten, Case M; Peña, Jasquelin

    2016-08-10

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

  16. Pseudometallophytes colonising Pb/Zn mine tailings: a description of the plant-microorganism-rhizosphere soil system and isolation of metal-tolerant bacteria.

    PubMed

    Becerra-Castro, C; Monterroso, C; Prieto-Fernández, A; Rodríguez-Lamas, L; Loureiro-Viñas, M; Acea, M J; Kidd, P S

    2012-05-30

    The plant-microorganism-soil system of three pseudometallophytes (Betula celtiberica, Cytisus scoparius and Festuca rubra) growing in a Pb/Zn mine was characterised. Plant metal accumulation, soil metal fractions (rhizosphere and non-vegetated) and bacterial densities were determined. Total Cd, Pb and Zn in non-vegetated soils was up to 50, 3000 and 20,000 mg kg(-1) dry weight, respectively. The residual fraction dominated non-vegetated soils, whereas plant-available fractions became important in rhizosphere soils. All plant species effectively excluded metals from the shoot. F. rubra presented a shoot:root transport factor of ≤0.2 and this population could be useful in future phytostabilisation trials. Culturable bacterial densities and diversity were low (predominantly Actinobacteria). Rhizosphere soils hosted higher total and metal-tolerant bacterial densities. Seventy-four metal-tolerant rhizobacteria were isolated, and characterised genotypically (BOX-PCR, 16S rDNA) and phenotypically [Cd/Zn tolerance, biosurfactant production and plant growth promoting (PGP) traits]. Several isolates resisted high concentrations of Cd and Zn, and only a few presented PGP traits. Fourteen isolates were evaluated for promoting plant growth of two species (Salix viminalis and Festuca pratensis). Thirteen inoculants enhanced growth of F. pratensis, while only three enhanced growth of S. viminalis. Growth enhancement could not always be related to isolate PGP traits. In conclusion, some isolates show potential application in phytostabilisation or phytoextraction techniques. PMID:22483595

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

    SciTech Connect

    Liu, Shuling Li, Honglin; Yan, Lu

    2013-09-01

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

  18. Spectroscopic Cathodoluminescence Studies of the ZnTe:Cu Contact Process for CdS/CdTe Solar Cells: Preprint

    SciTech Connect

    Gessert, T. A.; Romero, M. J.; Johnston, S.; Keyes, B.; Dippo, P.

    2002-05-01

    This conference paper describes the spectroscopic cathodoluminescence (CL), electron-beam induced current (EBIC), and capacitance-Voltage (C-V) measurements are used to study the formation of CdS/CdTe devices processed using ion-beam milling and a ZnTe:Cu/Ti contact. Results show heating in vacuum at {approx}360 C and ion-beam milling lead to observable changes in the CL emission from the CdCl2-treated CdTe surface. Changes in the CL spectrum are also observed as ZnTe:Cu layer thickness increases. These changes are correlated to published studies of defect levels and shown to be due, possibly, to an n-type region existing between the ZnTe:Cu contact interface and the p-CdTe layers. This n-type region is eliminated once a sufficiently thick ZnTe:Cu layer is produced.

  19. CdSeS/ZnS alloyed nanocrystal lifetime and blinking studies under electrochemical control.

    PubMed

    Qin, Wei; Shah, Raman A; Guyot-Sionnest, Philippe

    2012-01-24

    Alloyed CdSeS nanocrystals allow tuning between the CdSe and CdS band edges while remaining relatively small. The CdSeS cores also lead to a reduced electron confinement energy and a slower biexciton decay rate compared to CdSe cores of similar sizes. A ZnS shell synthesis procedure allows stable CdSeS/ZnS colloidal quantum dots (QDs) suitable for single dot imaging. These are compared to CdSe/ZnS of similar core size. The blinking off-exponents of the CdSeS/ZnS dots in air and on a glass substrate were slightly larger. Using electrochemistry with ensemble and single dot measurements, the trion lifetime of CdSeS/ZnS dot is resolved to be ~0.75 ns, while it is about 0.15 ns for CdSe/ZnS. In addition, the blinking behavior of single CdSeS/ZnS QDs is largely suppressed when in the trion state.

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

    NASA Astrophysics Data System (ADS)

    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

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

    NASA Astrophysics Data System (ADS)

    Sánchez-Chardi, Alejandro

    2016-04-01

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

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

    PubMed

    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

    2009-03-01

    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.

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

    NASA Astrophysics Data System (ADS)

    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

  4. ADVANCED READOUT ELECTRONICS FOR MULTIELEMENT CdZnTe SENSORS.

    SciTech Connect

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

    2002-07-08

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

  5. Purification of CdZnTe by Electromigration

    DOE PAGES

    Kim, K.; Kim, Sangsu; Hong, Jinki; Lee, Jinseo; Hong, Taekwon; Bolotnikov, A. E.; Camarda, G. S.; James, R. B.

    2015-04-14

    Electro-migration of ionized/electrically active impurities in CdZnTe (CZT) was successfully demonstrated at elevated temperature with an electric field of 20 V/mm. Copper, which exists in positively charged states, electro-migrated at a speed of 15 lm/h in an electric field of 20 V/mm. A notable variation in impurity concentration along the growth direction with the segregation tendency of the impurities was observed in an electro-migrated CZT boule. Notably, both Ga and Fe, which exist in positively charged states, exhibited the opposite distribution to that of their segregation tendency in Cd(Zn)Te. Furthermore, a CZT detector fabricated from the middle portion of themore » electromigrated CZT boule showed an improved mobility-lifetime product of 0.91 10-2 cm2 /V, compared to that of 1.4 10-3 cm2 /V, observed in an as-grown (non-electro-migrated) CZT detector. The optimum radiation detector material would have minimum concentration of deep traps required for compensation.« less

  6. Purification of CdZnTe by Electromigration

    SciTech Connect

    Kim, K.; Kim, Sangsu; Hong, Jinki; Lee, Jinseo; Hong, Taekwon; Bolotnikov, A. E.; Camarda, G. S.; James, R. B.

    2015-04-14

    Electro-migration of ionized/electrically active impurities in CdZnTe (CZT) was successfully demonstrated at elevated temperature with an electric field of 20 V/mm. Copper, which exists in positively charged states, electro-migrated at a speed of 15 lm/h in an electric field of 20 V/mm. A notable variation in impurity concentration along the growth direction with the segregation tendency of the impurities was observed in an electro-migrated CZT boule. Notably, both Ga and Fe, which exist in positively charged states, exhibited the opposite distribution to that of their segregation tendency in Cd(Zn)Te. Furthermore, a CZT detector fabricated from the middle portion of the electromigrated CZT boule showed an improved mobility-lifetime product of 0.91 10-2 cm2 /V, compared to that of 1.4 10-3 cm2 /V, observed in an as-grown (non-electro-migrated) CZT detector. The optimum radiation detector material would have minimum concentration of deep traps required for compensation.

  7. Purification of CdZnTe by electromigration

    SciTech Connect

    Kim, K.; Kim, Sangsu; Hong, Jinki; Lee, Jinseo; Hong, Taekwon; Bolotnikov, A. E.; Camarda, G. S.; James, R. B.

    2015-04-14

    Electro-migration of ionized/electrically active impurities in CdZnTe (CZT) was successfully demonstrated at elevated temperature with an electric field of 20 V/mm. Copper, which exists in positively charged states, electro-migrated at a speed of 15 μm/h in an electric field of 20 V/mm. A notable variation in impurity concentration along the growth direction with the segregation tendency of the impurities was observed in an electro-migrated CZT boule. Notably, both Ga and Fe, which exist in positively charged states, exhibited the opposite distribution to that of their segregation tendency in Cd(Zn)Te. A CZT detector fabricated from the middle portion of the electro-migrated CZT boule showed an improved mobility-lifetime product of 0.91 × 10{sup −2} cm{sup 2}/V, compared with that of 1.4 × 10{sup −3} cm{sup 2}/V, observed in an as-grown (non-electro-migrated) CZT detector. The optimum radiation detector material would have minimum concentration of deep traps required for compensation.

  8. Toxicity of Pb and of Pb/Cd combination on the springtail Folsomia candida in natural soils: reproduction, growth and bioaccumulation as indicators.

    PubMed

    Bur, T; Crouau, Y; Bianco, A; Gandois, L; Probst, A

    2012-01-01

    The toxicity of Pb and Cd+Pb was assessed on the Collembola F. candida in two cultivated soils (SV and AU) with low organic matter (OM) content and circumneutral to basic pH, and an acid forested soil (EPC) with high OM content. Collembola reproduction and growth as well as metal content in Collembola body, in soil, exchangeable fraction and soil solutions, pH and DOC were investigated. Pb and Cd+Pb were the highest in exchangeable fraction and soil solution of the acidic soils. Soil solution pH decreased after metal spiking in every soil due to metal adsorption, which was similar for Cd and the highest in AU for Pb. With increasing Pb and Cd+Pb, the most important reproduction decrease was in EPC soil. The LOEC for reproduction after metal addition was 2400 (Pb) and 200/2400 (Cd/Pb), 1200 and 100/1200, 300 and 100/1200 μg g(-1) for AU, SV and EPC, respectively. The highest and the lowest Pb toxicity was observed for EPC and AU bulk soil, respectively. The metal in Collembola increased with increasing soil concentration, except in AU, but the decreasing BF(solution) with increasing concentrations indicates a limited metal transfer to Collembola or an increased metal removal. Loading high Pb concentrations decreases Cd absorption by the Collembola, but the reverse was not true. The highest Pb toxicity in EPC can be explained by pH and OM content. Because of metal complexation, OM might have a protective role but its ingestion by Collembola lead to higher toxicity. Metal bioavailability in Collembola differs from soil solution indicating that soil solution is not sufficient to evaluate toxicity in soil organisms. The toxicity as a whole decreased when metals were combined, except for Pb in AU, due to adsorption competition between Cd and Pb on clay particles and OM sites in AU and EPC soils, respectively. PMID:22113108

  9. Engineering Zn1-xCdxS/CdS Heterostructures with Enhanced Photocatalytic Activity.

    PubMed

    Li, Kui; Chen, Rong; Li, Shun-Li; Xie, Shuai-Lei; Dong, Long-Zhang; Kang, Zhen-Hui; Bao, Jian-Chun; Lan, Ya-Qian

    2016-06-15

    Various porous Zn1-xCdxS/CdS heteorostructures were achieved via in situ synthesis method with organic amines as the templates. Because of the larger radius of Cd(2+) than that of Zn(2+), CdS quantum dots are formed and distributed uniformly in the network of Zn1-xCdxS. The Zn1-xCdxS/CdS heterostructure with small Cd content (10 at%) derived from ethylenediamine shows very high H2-evolution rate of 667.5 μmol/h per 5 mg photocatalyst under visible light (λ ≥ 420 nm) with an apparent quantum efficiency of 50.1% per 5 mg at 420 nm. Moreover, this Zn1-xCdxS/CdS heterostructure photocatalyst also shows an excellent photocatalytic stability over 100 h. PMID:27172231

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

    NASA Astrophysics Data System (ADS)

    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.

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

    SciTech Connect

    Kuhnert, B.R.; Kuhnert, P.M.; Groh-Margo, S.; Webster, S.; Erhard, P.

    1986-03-05

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

  12. Synthesis and characterization of quasi-aligned ZnCdO nanorods

    NASA Astrophysics Data System (ADS)

    Wang, F. Z.; Ye, Z. Z.; Ma, D. W.; Zhu, L. P.; Zhuge, F.; He, H. P.

    2005-10-01

    Quasi-aligned ZnCdO single-crystal nanorods were prepared for the first time by using thermal evaporation of Zn and CdCl2 on a Si substrate with the presence of Au catalyst. The maximum Cd content was up to about 16.7at.%, which was significantly larger than the thermodynamic solid solubility limits. The ZnCdO nanorods have uniform flat hexagonal crystallographic planes with diameters of about 150nm. Notably, with the Cd content increasing, the ultraviolet near-band-edge emission was redshifted to 407nm(3.04eV ) from 386nm(3.21eV). The direct modulation of the band gap caused by Cd substitution is responsible for the redshift. The possible growth mechanism of the ZnCdO nanorods was discussed.

  13. Cd and Te-based ohmic contact materials to p-Type ZnSe

    NASA Astrophysics Data System (ADS)

    Hashimoto, K.; Koide, Y.; Tadanaga, O.; Oku, T.; Teraguchi, N.; Tomomuea, Y.; Suzuki, A.; Murakami, Masanori

    1996-12-01

    In order to explore a possibility of forming an intermediate semiconductor layer with low Schottky barrier by the conventional deposition and annealing technique, the electrical properties of Cd and Te-based contacts on the nitrogendoped ZnSe substrates have been investigated. Cd in the Cd/W contact reacted with the ZnSe substrate after annealing at temperatures above 250°C and formed epitaxial Ccx}Zn1-xSe layers, leading to reduction of the “turn-on” voltage (VT) from about 11 to 6 V (here, a slash “/” between Cd and W means the deposition sequence). The reduction of the Vn} value by annealing at elevated temperatures was also observed for the Bi-Cd/W and In-Cd/W contacts. The average Cd composition (x) in the Cdn}Zn1-xSe layers was measured to be larger than 0.9, which agreed with the values estimated from the calculated Cd-Zn-Se phase diagrams. The ohmic behavior was strongly influenced by the thickness of the CdxZn1-xSe layer, the density of misfit dislocations formed at the interface between the Cdx Zn1-x Se and the ZnSe, and/or the total area of the Cd Zn. Se layers covering the ZnSe surface. The present result suggests that formation of the large-areal CcxZn1-xSe layers with thin thickness is crucial to achieve further reduction of the VT value by the conventional deposition and annealing technique. Also, the VT reduction was not obtained for the Te/W contact even after annealing at temperatures close to 300°C, which was explained to be due to absence of ternary ZnSe1-xTen intermediate layers.

  14. Investigation of CdZnTe for Thin-Film Tandem Solar Cell Applications: Preprint

    SciTech Connect

    Dhere, R.; Gessert, T.; Zhou, J.; Asher, S.; Pankow, J.; Moutinho, H.

    2003-04-01

    Modeling of two-junction tandem devices shows that for optimal device performance, the bandgap of the top cell should be around 1.6-1.8 eV. CdZnTe alloys can be tailored to yield bandgaps in the desired range. In this study, we considered were used to fabricate these films, using close-spaced sublimation (CSS) and radio-frequency sputtering (RFS) techniques. In the first approach, we used mixed powders of CdTe and ZnTe as the source for film deposition by CSS. Even for the ZnTe/CdTe (95:5 ratio) source material, the deposited films were entirely CdTe due to higher vapor pressure of CdTe. In the second approach, we used pre-alloyed CdZnTe powders (CERAC, Inc.) as the source. Due to the lower sticking coefficient of Zn, even for the source composition of 75% Zn, these films contained very low quantities of Zn (~5%). We tried unsuccessfully to increase the Zn content in the films by confining Zn vapor by enclosing the region between the source and substrate, reducing the substrate temperature to 400C, and adjusting the source/substance distance. Finally, we used thin-film couples consisting of 300-nm-thick CdTe deposited by CSS and 300-nm-thick ZnTe deposited by RFS; the samples were then heat-treated in cadmium chloride vapor. Compositional analysis of the samples showed extensive interdiffusion of Cd and Zn for the annealed samples. We will present the data on the various stack configurations of CdTe and ZnTe, the effect of different post-deposition anneals, the effect of oxygen on the interdiffusion and alloy formation and its possible correlation to the device performance degradation.

  15. An experimental and thermodynamic equilibrium investigation of the Pb, Zn, Cr, Cu, Mn and Ni partitioning during sewage sludge incineration.

    PubMed

    Liu, Jingyong; Fu, Jiewen; Ning, Xun'an; Sun, Shuiyu; Wang, Yujie; Xie, Wuming; Huang, Shaosong; Zhong, Sheng

    2015-09-01

    The effects of different chlorides and operational conditions on the distribution and speciation of six heavy metals (Pb, Zn, Cr, Cu, Mn and Ni) during sludge incineration were investigated using a simulated laboratory tubular-furnace reactor. A thermodynamic equilibrium investigation using the FactSage software was performed to compare the experimental results. The results indicate that the volatility of the target metals was enhanced as the chlorine concentration increased. Inorganic-Cl influenced the volatilization of heavy metals in the order of Pb>Zn>Cr>Cu>Mn>Ni. However, the effects of organic-Cl on the volatility of Mn, Pb and Cu were greater than the effects on Zn, Cr and Ni. With increasing combustion temperature, the presence of organic-Cl (PVC) and inorganic-Cl (NaCl) improved the transfer of Pb and Zn from bottom ash to fly ash or fuse gas. However, the presence of chloride had no obvious influence on Mn, Cu and Ni. Increased retention time could increase the volatilization rate of heavy metals; however, this effect was insignificant. During the incineration process, Pb readily formed PbSiO4 and remained in the bottom ash. Different Pb compounds, primarily the volatile PbCl2, were found in the gas phase after the addition of NaCl; the dominant Pb compounds in the gas phase after the addition of PVC were PbCl2, Pb(ClO4)2 and PbCl2O4.

  16. Sedimentary model for the giant Broken Hill Pb-Zn deposit, Australia

    NASA Astrophysics Data System (ADS)

    Wright, John V.; Haydon, Robert C.; McConachy, Geoff W.

    1987-07-01

    During the past 15 years there has been increasing acceptance of a volcanic exhalative origin for the giant 300-Mt Broken Hill Pb-Zn orebody. Supposedly, silicic pyroclastic rock types have been identified in the host-rock succession, and because of an association with basic volcanics (amphibolites), comparison is made with Phanerozoic continental rifts. The orebody has also been described as distal and deep water. We report that the so-called silicic volcanic rocks are all normal clastic sediments. The metasedimentary succession (more than 5 km thick) is interpreted as a series of major continental, fluvio-deltaic, progradational wedges interfingering with marine transgressive cycles, deposited in a gradually deepening basin. Pb-Zn mineralization is hosted by shallow-marine sands that later became reservoirs for the metal-bearing brines. Basin formation, stratigraphic architecture, and Pb-Zn mineralization can all be interpreted in terms of concepts understood from studies of the development of younger sedimentary basins. The inference is that Pb-Zn mineralization was generated by compactive expulsion of metal-bearing brines during accumulation of the sedimentary pile. *Request reprints from McConachy

  17. Study on structure and properties of CuZn40Pb alloy

    NASA Astrophysics Data System (ADS)

    Achiţei, D. C.; Minciună, M. G.; Vizureanu, P.; Sandu, A. V.; Cimpoeşu, R.; Istrate, B.

    2016-06-01

    The paper shows aspects about the behavior of Cu-Zn-Pb alloys a subjected to the temperatures variation and corrosion resistance in saline medium (sea water). The chemical composition was determined by spectral analysis on optical spectrometer, type Foundry Masters. The experiments are completed by a microstructure analysis made on scanning electronic microscope.

  18. Investigation of transport properties of ZnO/PbS heterojunction solar cells

    NASA Astrophysics Data System (ADS)

    Cheng, Yang; Whitaker, Michael D. C.; Whiteside, Vincent R.; Bumm, Lloyd A.; Sellers, Ian R.

    Lead sulfide (PbS) and lead selenide (PbSe) colloidal quantum dots (CQDs) are considered as a potential candidate material for solar cell applications due to their large band gap tunability range (0.5 to 1.7 eV) and cost-effective solution based processing. A series of Glass/ITO/ZnO/PbS/MoO3/Au heterojunction solar cells were processed and analyzed. A stable (reproducible) 2% conversion efficiency under 1-sun is achieved based on the result of J - V measurements. Absorbance and external quantum efficiency (EQE) measurements clearly show photo-generated carrier extraction from PbS active layers in the solar cell. However, a non-ideal J - V behavior is observed in current-voltage measurements. This behavior may be attributed to a high density of trap states at the QD surface or defect states at the PbS/ZnO or ITO/ZnO interfaces. C-V and Impedance spectroscopy measurements are used to study this unusual behavior. These techniques could also help probe the transport properties and limitation of these heterojunction solar cells. This research is funded through NASA EPSCoR program Award # NNX13AN101A.

  19. Timing of foliar Zn application plays a vital role in minimizing Cd accumulation in wheat.

    PubMed

    Saifullah; Javed, Hina; Naeem, Asif; Rengel, Zed; Dahlawi, Saad

    2016-08-01

    Due to chemical and biochemical similarities between cadmium (Cd) and zinc (Zn), application of Zn may minimize Cd uptake by plants and ameliorate its toxicity. However, there is poor understanding of the comparative effectiveness of the foliar Zn application at different growth stages on Cd toxicity and accumulation in wheat. The present study was carried out to compare the effectiveness of foliarly applied Zn at different stages of plant growth to minimize Cd accumulation in wheat grains. Wheat (cv AARI-2011) was grown at three levels of soil Cd (0, 2.5, and 5.0 mg kg(-1)). Foliar application of Zn was carried out at either tillering, jointing, booting, heading, or grain filling stage using 0.05 % w/v aqueous solution of ZnSO4 · 7H2O. Increasing soil Cd had a negative effect on growth and yield attributes, including tiller production, root length and dry weight, plant height, 100-grain weight and grain and straw yield. Zinc foliar spray increased grain yield by increasing tiller production; importantly, an application at booting was more effective than at other stages. Foliarly applied Zn decreased Cd concentration in the roots, straw, and grain. Similar to grain yield, the largest decrease (74 %) in Cd concentration was associated with Zn foliar spray at booting. Grain yield was negatively related to grain Cd concentration which in turn showed a negative relationship with Zn concentration in leaves and grains. It is concluded that the booting stage is the suitable time for foliar application of Zn to (i) effectively minimize a Cd-induced loss in grain yield and (ii) decrease grain Cd concentration.

  20. Timing of foliar Zn application plays a vital role in minimizing Cd accumulation in wheat.

    PubMed

    Saifullah; Javed, Hina; Naeem, Asif; Rengel, Zed; Dahlawi, Saad

    2016-08-01

    Due to chemical and biochemical similarities between cadmium (Cd) and zinc (Zn), application of Zn may minimize Cd uptake by plants and ameliorate its toxicity. However, there is poor understanding of the comparative effectiveness of the foliar Zn application at different growth stages on Cd toxicity and accumulation in wheat. The present study was carried out to compare the effectiveness of foliarly applied Zn at different stages of plant growth to minimize Cd accumulation in wheat grains. Wheat (cv AARI-2011) was grown at three levels of soil Cd (0, 2.5, and 5.0 mg kg(-1)). Foliar application of Zn was carried out at either tillering, jointing, booting, heading, or grain filling stage using 0.05 % w/v aqueous solution of ZnSO4 · 7H2O. Increasing soil Cd had a negative effect on growth and yield attributes, including tiller production, root length and dry weight, plant height, 100-grain weight and grain and straw yield. Zinc foliar spray increased grain yield by increasing tiller production; importantly, an application at booting was more effective than at other stages. Foliarly applied Zn decreased Cd concentration in the roots, straw, and grain. Similar to grain yield, the largest decrease (74 %) in Cd concentration was associated with Zn foliar spray at booting. Grain yield was negatively related to grain Cd concentration which in turn showed a negative relationship with Zn concentration in leaves and grains. It is concluded that the booting stage is the suitable time for foliar application of Zn to (i) effectively minimize a Cd-induced loss in grain yield and (ii) decrease grain Cd concentration. PMID:27164881

  1. Formation of highly luminescent Zn1-xCdxSe nanocrystals using CdSe and ZnSe seeds

    NASA Astrophysics Data System (ADS)

    Zhang, Ruili; Yang, Ping

    2013-05-01

    High-quality colloidal Zn1-xCdxSe nanocrystals (NCs) with tunable photoluminescence (PL) from blue to orange were synthesized using oleic acid as a capping agent. The Zn1-xCdxSe NCs were prepared through two approaches: using CdSe or ZnSe seeds. In the case of CdSe NCs as seeds, Zn1-xCdxSe NCs were fabricated by the reaction of Zn, Cd, and Se precursors in the coordinating solvent system at high temperature. The Zn1-xCdxSe NCs revealed orange emitting. A significant blue-shift of absorption and PL spectra were observed with time, indicating the formation of ternary NCs. In contrast, Zn1-xCdxSe NCs revealed blue to green PL for ZnSe NCs as seeds. This is ascribed to an embryonic nuclei-induced alloying process. With increasing time, the Zn1-xCdxSe NCs exhibited a red-shift both in their absorption and PL spectra. This is attributed to the engineering in band gap energy via the control of NC composition. The PL properties of as-prepared alloyed NCs are comparable or even better than those for the parent binary systems. The PL peak wavelength of the Zn1-xCdxSe NCs depended strongly on reaction time and the molar ratio of Cd/Zn. The Zn1-xCdxSe NCs revealed a spherical morphology and exhibited a wurtzite structure according to transmission electron microscopy observation and an X-ray diffraction analysis.

  2. Carbonate-hosted nonsulphide Zn-Pb mineralization of southern British Columbia, Canada

    NASA Astrophysics Data System (ADS)

    Paradis, Suzanne; Keevil, Halley; Simandl, George J.; Raudsepp, Mati

    2015-12-01

    Many carbonate-hosted sulphide deposits in the Salmo district of southern British Columbia have near-surface Zn- and Pb-bearing iron oxide-rich gossans. The gossans formed when carbonate-hosted, base metal sulphides were subjected to intense supergene weathering processes and metals were liberated by the oxidation of sulphide minerals. Two types of supergene carbonate-hosted nonsulphide deposits, direct replacement (`red ore') and wallrock replacement (`white ore'), are present in the Salmo district. The direct replacement deposits formed by the oxidation of primary sulphides; the base metals passed into solution and were redistributed and trapped within the space occupied by the oxidized portion of the sulphide protore. Depending on the extent of replacement of the sulphides by Zn-, Pb- and Fe-bearing oxides, silicates, carbonates and phosphates, the resulting ore can be called `mixed' (sulphides and nonsulphides) or simply `nonsulphide'. The wallrock replacement deposits formed when base metals liberated by the oxidation of sulphides were transported by circulating supergene solutions down and/or away from the sulphides to form wallrock replacement deposits. The direct replacement nonsulphide zones of the Salmo district overlay the sulphide bodies in which they replaced the sulphides and carbonates, forming large irregular replacement masses, encrustations and open-space fillings. They consist predominantly of hematite, goethite, hemimorphite [Zn4Si2O7(OH)2·H2O], minor hydrozincite [Zn5(CO3)2(OH)6], cerussite [PbCO3] and traces of willemite [Zn2SiO4]. The wallrock replacement zones consist mainly of hemimorphite with local occurrences of iron oxides, hopeite [Zn3(PO4)2·4H2O] and tarbuttite [Zn2(PO4)(OH)]. No remnants of sulphides were observed in the replacement zones. The Salmo nonsulphide deposits were formed by prolonged weathering of Mississippi Valley-type (MVT) mineralization that underwent dissolution and oxidation of the pyrite, sphalerite and galena

  3. [Effect and bioaccumulation of heavy metals (Zn, Cd) on Micractinium pusillum ALGA].

    PubMed

    Toumi, A; Belkoura, M; Benabdallah, S; El Alami, M; Idrissi, L Loukili; Nejmeddine, A

    2007-01-01

    Heavy metals (Zn and Cd) effect and their bioaccumulation by a microalga Micractinium pusillum were investigated. Results showed that Cd was more toxic than Zn on Micractinium pusillum. Indeed, inhibitory concentrations of 50% of alga population in 72h (IC(50,72h)) were 0.28 and 0.34 mg l(-1) respectively for Cd and Zn. On the other hand, metal extracted rates from medium solution were more important for Zn than for Cd, essentially for the two first concentrations tested (0.06 and 0.12 mg l(-1)). Furthermore, Zn and Cd extracted proportions were more important for the low concentrations tested and decreased progressively with increasing concentrations applied. This mechanism of extraction corresponds principally to their biosorption by Micractinium pusillum.

  4. Thallium transformation and partitioning during Pb-Zn smelting and environmental implications.

    PubMed

    Liu, Juan; Wang, Jin; Chen, Yongheng; Xie, Xiaofan; Qi, Jianying; Lippold, Holger; Luo, Dinggui; Wang, Chunlin; Su, Longxiao; He, Lucheng; Wu, Qiwei

    2016-05-01

    Thallium (Tl) is a toxic and non-essential heavy metal. Raw Pb-Zn ores and solid smelting wastes from a large Pb-Zn smelting plant - a typical thallium (Tl) pollution source in South China, were investigated in terms of Tl distribution and fractionation. A modified IRMM (Institute for Reference Materials and Measurement, Europe) sequential extraction scheme was applied on the samples, in order to uncover the geochemical behavior and transformation of Tl during Pb-Zn smelting and to assess the potential environmental risk of Tl arising from this plant. Results showed that the Pb-Zn ore materials were relatively enriched with Tl (15.1-87.7 mg kg(-1)), while even higher accumulation existed in the electrostatic dust (3280-4050 mg kg(-1)) and acidic waste (13,300 mg kg(-1)). A comparison of Tl concentration and fraction distribution in different samples clearly demonstrated the significant role of the ore roasting in Tl transformation and mobilization, probably as a result of alteration/decomposition of related minerals followed by Tl release and subsequent deposition/co-precipitation on fine surface particles of the electrostatic dust and acidic waste. While only 10-30% of total Tl amounts was associated with the exchangeable/acid-extractable fraction of the Pb-Zn ore materials, up to 90% of total Tl was found in this fraction of the electrostatic dust and acidic waste. Taking into account the mobility and bioavailability of this fraction, these waste forms may pose significant environmental risk. PMID:26840520

  5. Comparison of serum Concentration of Se, Pb, Mg, Cu, Zn, between MS patients and healthy controls

    PubMed Central

    Alizadeh, Anahita; Mehrpour, Omid; Nikkhah, Karim; Bayat, Golnaz; Espandani, Mahsa; Golzari, Alireza; Jarahi, Lida; Foroughipour, Mohsen

    2016-01-01

    Introduction Multiple Sclerosis (MS) is defined as one of the inflammatory autoimmune disorders and is common. Its exact etiology is unclear. There are some evidences on the role of environmental factors in susceptible genetics. The aim of this study is to evaluate the possible role of Selenium, Zinc, Copper, Lead and Magnesium metals in Multiple Sclerosis patients. Methods In the present analytical cross-sectional study, 56 individuals including 26 patients and 30 healthy controls were enrolled in the evaluation. The serum level of Se, Zn, Cu, Pb were quantified in graphite furnace conditions and flame conditions by utilizing an atomic absorption Perkin Elmer spectrophotometer 3030. The serum levels of Mg were measured by auto analyzer 1500 BT. The mean level of minerals (Zn, Pb, Cu, Mg, Se) in serum samples were compared in both cases and controls. The mean level of minerals (Zn, Pb, Cu, Mg, Se) in serum samples were compared in both cases and controls by using independent-samples t-test for normal distribution and Mann-Whitney U test as a non-parametric test. All statistical analyses were carried out using SPSS 11.0. Results As well as the Zn, Cu, and Se, there was no significant difference between MS patients and healthy individuals in Pb concentrations (p-value = 0.11, 0.14, 0.32, 0.20 respectively) but the level of Mg was significantly different (p= 0.001). Conclusion All serum concentrations of Zn, Pb, Se, Cu in both groups were in normal ranges and there was no difference in MS patients compared with the healthy group who were matched in genetics. Blood level of Mg was significantly lower in MS patients. But it should be noted that even with the low level of serum magnesium in MS patients, this value is still in the normal range. PMID:27757186

  6. Thallium transformation and partitioning during Pb-Zn smelting and environmental implications.

    PubMed

    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.

  7. Effect of Zn-Cd interdiffusion on the band structure and spontaneous emission of ZnO/Zn1-xCdxO/ZnO quantum wells

    NASA Astrophysics Data System (ADS)

    Shtepliuk, I.; Khranovskyy, V.; Yakimova, R.

    2015-09-01

    Needs in more-efficient visible light sources based on quantum wells (QWs) requires the diversification of traditional optoelectronics' materials as well as development of the cost-effective approaches for reliable quantum confinement engineering. Interdiffusion approach has a great potential to become a simple method for controlling the optical properties of QWs and diminishing the quantum confined Stark effect (QCSE). In this work we theoretically study the effect of Zn-Cd interdiffusion in ZnCdO/ZnO QWs on their band structure, optical matrix elements and spontaneous emission properties. The QW intermixing leads to improving both the transverse electric (TE) and transverse magnetic (TM) optical matrix elements due to enhancement of the overlap integral between electron and hole wave functions and modification of the confinement potential from triangle-shaped to parabolic-like. The optimized diffusion length 4 Å provided by the annealing at 700 K during 60 s was determined for 2 nm-thick Zn0.85Cd0.15O QW, which offers higher spontaneous emission rate in comparison to conventional QW. The reasonable interpretation of the interdiffusion effect on the optical properties of QWs is proposed in terms of low diffusion length and high diffusion length regimes. Thus, suitable combination of annealing duration and annealing temperature with the geometrical/compositional parameters of QWs can be the efficient way for improving the optical performance of ZnO-based QWs.

  8. Effect of metal mixture (Cu, Zn, Pb, and Ni) on cadmium partitioning in littoral sediments and its accumulation by the freshwater macrophyte Eriocaulon septangulare

    SciTech Connect

    Stewart, A.R.; Malley, D.F.

    1999-03-01

    The effect of a metal mixture (Cu, Zn, Pb, and Ni) on Cd fractionation in sediment and its accumulation by the freshwater macrophyte Eriocaulon septangulare was examined in an in situ experiment in the littoral zone at the Experimental Lakes Area, northwestern Ontario, Canada. Fresh sediment was spiked with Cd alone and together with the metal mixture at three concentration levels. Macrophytes were planted in the spiked sediment and placed at a water depth of 0.5 m. The distribution of Cd among sediment fractions (easily reducible [ER], reducible [R-ER], and organic [ORG]), pore water, and macrophytes was determined every 2 weeks for 10 weeks. Small differences among treatment levels in the recovery of Cd from the geochemical fractions were observed after 2 and 8 weeks but not after 10 weeks. At the highest concentration of the metal mixture, Cd repartitioned from the ER fraction onto the R-ER fraction after 2 weeks in situ. After 10 weeks, Cd was accumulated by the shoots and roots of E. septangulare and had not reached steady state. Significantly higher Cd concentrations were found in the shoots of plants in the treatment with Cd alone and the treatment with the highest concentration of the metal mixture than in treatments with intermediate levels of the mixture. Partitioning of Cd among geochemical fractions in sediment alone did not explain differences in tissue Cd concentrations related to treatment level.

  9. Molecular Beam Epitaxy Growth of HgCdTe on Large-Area Si and CdZnTe Substrates

    NASA Astrophysics Data System (ADS)

    Reddy, M.; Peterson, J. M.; Vang, T.; Franklin, J. A.; Vilela, M. F.; Olsson, K.; Patten, E. A.; Radford, W. A.; Bangs, J. W.; Melkonian, L.; Smith, E. P. G.; Lofgreen, D. D.; Johnson, S. M.

    2011-08-01

    This paper presents the status of HgCdTe growth on large-area Si and CdZnTe substrates at Raytheon Vision Systems (RVS). The different technological tools that were used to scale up the growth from 4 inch to 6 inch diameter on Si and from 4 cm × 4 cm to 8 cm × 8 cm on CdZnTe without sacrificing the quality of the layers are described. Extremely high compositional uniformity and low macrodefect density were achieved for single- and two-color HgCdTe layers on both Si and CdZnTe substrates. Finally, a few examples of detector and focal-plane array results are included to highlight the importance of high compositional uniformity and uniformly low macrodefect density of the epitaxial layers in obtaining high operability and low cluster outages in single- and two-color focal-plane arrays (FPAs).

  10. Photoresponse asymmetry of CdZnTe crystals

    SciTech Connect

    But, A. V. Mygal, V. P.; Phomin, A. S.

    2011-02-15

    It is shown that transformation of photoelectric characteristics of sensors based on Cd{sub 1-x}Zn{sub x}Te (x = 0.05-0.15) crystals into parametric spectral I({lambda})-dI/d{lambda}, kinetic I(t)-dI/dt, and dynamic U-I({Delta}y){sub f,{lambda}} signatures (I({lambda}) is the photocurrent, U is the voltage, f is the frequency, t is the time, and y is the coordinate) makes it possible to reveal integrative photoresponse features caused by the photoresponse asymmetry and nonlinearity. Indices of asymmetry and balance of dynamic and energy photoinduced states are suggested; these indices represent systematically the effect of multiscale fields on photoelectronic processes. Using these indices, the ranges of external effects at which systematic features of photoresponse of sensors are minimal or maximal are determined, which makes it possible to increase the efficiency of purposeful selection and treatment of sensors.

  11. Development of prototype pixellated PIN CdZnTe detectors

    NASA Astrophysics Data System (ADS)

    Narita, Tomohiko; Bloser, Peter F.; Grindlay, Jonathan E.; Sudharsanan, R.; Reiche, C.; Stenstrom, Claudia

    1998-07-01

    We report initial results from the design and evaluation of two pixellated PIN Cadmium Zinc Telluride detectors and an ASIC-based readout system. The prototype imaging PIN detectors consist of 4 X 4 1.5 mm square indium anode contacts with 0.2 mm spacing and a solid cathode plane on 10 X 10 mm CdZnTe substrates of thickness 2 mm and 5 mm. The detector readout system, based on low noise preamplifier ASICs, allows for parallel readout of all channels upon cathode trigger. This prototype is under development for use in future astrophysical hard X-ray imagers with 10 - 600 keV energy response. Measurements of the detector uniformity, spatial resolution, and spectral resolution will be discussed and compared with a similar pixellated MSM detector. Finally, a prototype design for a large imaging array is outlined.

  12. Comparison of essential and non-essential element distribution in leaves of the Cd/Zn hyperaccumulator Thlaspi praecox as revealed by micro-PIXE.

    PubMed

    Vogel-Mikus, Katarina; Simcic, Jure; Pelicon, Primoz; Budnar, Milos; Kump, Peter; Necemer, Marijan; Mesjasz-Przybyłowicz, Jolanta; Przybyłowicz, Wojciech J; Regvar, Marjana

    2008-10-01

    A detailed localization of elements in leaf tissues of the field-collected Cd/Zn hyperaccumulator Thlaspi praecox (Brassicaceae) growing at a highly metal-polluted site was determined by micro-proton-induced X-ray emission (micro-PIXE) in order to reveal and compare nutrient and non-essential element accumulation patterns in the case of multiple metal accumulation within particular leaf tissues, including the detailed distribution between apoplast and symplast regions. On the larger scans, the highest concentrations of metals were observed in the epidermis, S and Ca in the palisade mesophyll, Cl in the spongy mesophyll and vascular bundles, and P and K in the vascular bundles. On the more detailed scans, the highest Cd, Pb, Cl and K concentrations were observed in vascular bundle collenchyma. The relative element distribution (%) was calculated based on concentrations of elements in particular leaf tissues and their relative weight portions, indicating that most of the accumulated Zn was located in epidermises, while the majority of Cd and Pb was distributed within the mesophyll. Detailed scans of epidermal/mesophyll tissues revealed that Zn was mainly accumulated and detoxified in the symplast of large vacuolated epidermal cells, Cd in the mesophyll symplast, and Pb in the mesophyll symplast and apoplast.

  13. Comparison of essential and non-essential element distribution in leaves of the Cd/Zn hyperaccumulator Thlaspi praecox as revealed by micro-PIXE.

    PubMed

    Vogel-Mikus, Katarina; Simcic, Jure; Pelicon, Primoz; Budnar, Milos; Kump, Peter; Necemer, Marijan; Mesjasz-Przybyłowicz, Jolanta; Przybyłowicz, Wojciech J; Regvar, Marjana

    2008-10-01

    A detailed localization of elements in leaf tissues of the field-collected Cd/Zn hyperaccumulator Thlaspi praecox (Brassicaceae) growing at a highly metal-polluted site was determined by micro-proton-induced X-ray emission (micro-PIXE) in order to reveal and compare nutrient and non-essential element accumulation patterns in the case of multiple metal accumulation within particular leaf tissues, including the detailed distribution between apoplast and symplast regions. On the larger scans, the highest concentrations of metals were observed in the epidermis, S and Ca in the palisade mesophyll, Cl in the spongy mesophyll and vascular bundles, and P and K in the vascular bundles. On the more detailed scans, the highest Cd, Pb, Cl and K concentrations were observed in vascular bundle collenchyma. The relative element distribution (%) was calculated based on concentrations of elements in particular leaf tissues and their relative weight portions, indicating that most of the accumulated Zn was located in epidermises, while the majority of Cd and Pb was distributed within the mesophyll. Detailed scans of epidermal/mesophyll tissues revealed that Zn was mainly accumulated and detoxified in the symplast of large vacuolated epidermal cells, Cd in the mesophyll symplast, and Pb in the mesophyll symplast and apoplast. PMID:18643900

  14. Pb(II) and Cd(II) removal from aqueous solutions by olive cake.

    PubMed

    Doyurum, Sabriye; Celik, Ali

    2006-11-01

    The removal of heavy metals from wastewater using olive cake as an adsorbent was investigated. The effect of the contact time, pH, temperature, and concentration of adsorbate on adsorption performance of olive cake for Pb(II) and Cd(II) ions were examined by batch method. Adsorption of Pb(II) and Cd(II) in aqueous solution onto olive cake was studied in single component. After establishing the optimum conditions, elution of these ions from the adsorbent surface was also examined. The optimum sorption conditions were determined for two elements. Maximum desorption of the Pb(II) and Cd(II) ions were found to be 95.92 and 53.97% by 0.5M HNO(3) and 0.2M HCl, respectively. The morphological analysis of the olive cake was performed by the scanning electron microscopy (SEM). PMID:16806680

  15. Speciation of Cd and Pb in dust emitted from sinter plant.

    PubMed

    Sammut, M L; Noack, Y; Rose, J; Hazemann, J L; Proux, O; Depoux, M; Ziebel, A; Fiani, E

    2010-01-01

    Many studies have provided evidence of the impact of heavy metals in atmospheric emission. Sinter plants represent the first step in steel production, and are important emitters of Cd and Pb. The toxicity of these two metals depends above all on their speciation. Particles collected before and after the filtration system were analysed to determine the Cd- and Pb-bearing phases, using analytical tools such as XRF, EXAFS or ICP-AES and chemical leaching (sequential extractions adapted to steel dusts). Results show that Pb is associated with carbonate and Cd with chloride. These two types of speciation lead to high solubility under common environmental conditions, which may produce impacts on the environment and health.

  16. Classification of Broken Hill-Type Pb-Zn-Ag Deposits: A Refinement

    NASA Astrophysics Data System (ADS)

    Spry, P. G.; Teale, G. S.; Steadman, J. A.

    2009-05-01

    Broken Hill Hill-type Pb-Zn-Ag (BHT) deposits constitute some of the largest ore deposits in the world. The Broken Hill deposit is the largest accumulation of Pb, Zn, and Ag on Earth and the Cannington deposit is currently the largest silver deposit. Characteristic features of BHT deposits include: 1. high Pb+Zn+Ag values with Pb > Zn; 2. Metamorphism to amphibolite-granulite facies; 3. Paleo-to Mesoprotoerozoic clastic metasedimentary host rocks; 4. Sulfides that are spatially associated with bimodal (felsic and mafic) volcanic rocks, and stratabound gahnite- and garnet-bearing rocks and iron formations, 5. Stacked orebodies with characteristic Pb:Zn:Ag ratios and skarn-like Fe-Mn-Ca-F gangue assemblages, and the presence of Cu, Au, Bi, As, and Sb; and 6. Sulfur-poor assemblages. Broken Hill (Australia) has a prominent footwall feeder zone whereas other BHT deposits have less obvious alteration zones (footwall garnet spotting and stratabound alteration haloes). Deposits previously regarded in the literature as BHT deposits are Broken Hill, Cannington, Oonagalabie, Menninie Dam, and Pegmont (Australia), Broken Hill, Swartberg, Big Syncline, and Gamsberg (South Africa), Zinkgruvan (Sweden), Sullivan, Cottonbelt, and Foster River (Canada), and Boquira (Brazil). Of these deposits, only the Broken Hill (Australia, South Africa), Pinnacles, Cannington, Pegmont, and Swartberg deposits are BHT deposits. Another BHT deposit includes the Green Parrot deposit, Jervois Ranges (Northern Territory). The Foster River, Gamsberg, and Sullivan deposits are considered to be "SEDEX deposits with BHT affinities", and the Oonagalabie, Green Mountain (Colorado), and Zinkgruvan are "VMS deposits with BHT affinities". In the Broken Hill area (Australia), Corruga-type Pb-Zn-Ag deposits occur in calc-silicate rocks and possess some BHT characteristics; the Big Syncline, Cottonbelt, Menninie Dam, and Saxberget deposits are Corruga-type deposits. SEDEX deposits with BHT affinities, VMS

  17. As-Received CdZnTe Substrate Contamination

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

    State-of-the-art as-received (112)B CdZnTe substrates were examined for surface impurity contamination, polishing damage, and tellurium precipitates/inclusions. A maximum surface impurity concentration of Al = 7.5 × 1014, Si = 3.7 × 1013, Cl = 3.12 × 1015, S = 1.7 × 1014, P = 7.1 × 1013, Fe = 1.0 × 1013, Br = 1.9 × 1012, and Cu = 4 × 1012 atoms cm-2 was observed on an as-received 6 × 6 cm wafer. As-received CdZnTe substrates have scratches and residual polishing grit on the (112)B surface. Polishing scratches are 0.3 nm in depth and 0.1 μm wide. The polishing grit density was observed to vary from wafer-to-wafer from ˜5 × 106 to 2 × 108 cm-2. Te precipitate/inclusion size and density was determined by near-infrared automated microscopy. A Te precipitate/inclusion diameter histogram was obtained for the near-surface (top ~140 μm) of a 6 × 6 cm substrate. The average areal Te precipitate/inclusion density was observed to be fairly uniform. However, there was a large density of Te precipitates/inclusions with a diameter significantly greater than the mean. Te precipitate/inclusion density >10 μm diameter = 2.8 × 103 cm-3. The large Te precipitates/inclusions are laterally non-uniformly distributed across the wafer.

  18. Production of ZnO and CdO-ZnO thin Films by Extraction-Pyrolytic Method

    NASA Astrophysics Data System (ADS)

    Cvetkovs, A.; Kiselova, O.; Rogulis, U.; Serga, V.; Ignatans, R.

    2016-06-01

    The extraction-pyrolytic method has been applied to produce the ZnO and CdO-ZnO thin films on glass and quartz glass substrates. According to X-ray diffraction measurements, the ZnO and CdO phases have been produced with an average size of crystallites about 8-42 nm in the films. The thickness of the layers measured by a profilometer has been up to 150 nm. The surface morphology measurements show that the surface of the films may be rough and non-continuous. The SEM results confirm the dependence between the preparation procedure and the quality of the thin film.

  19. Uptake and accumulation of potentially toxic metals (Zn, Cu and Pb) in soils and plants of Durgapur industrial belt.

    PubMed

    Kisku, Ganesh Chandra; Pandey, Poonam; Negi, Mahendra Pratap Singh; Misra, Virendra

    2011-11-01

    Uptake and accumulation of metals in crops may cause possible health risks through food chain. A field survey was conducted to investigate the accumulation of potentially toxic metals contamination in soil and plants irrigated with complexed industrial effluents. Concentration of Zn, Cu and Pb was 205-255,101-130,118-177 microg g(-1) in rhizosphere soils and 116-223, 57-102 and 63-95 microg g(-1) d. wt. in root and 95-186, 44-75 and 27-58 microg g(-1) d. wt. in shoot, respectively. The trend in Cu and Pb was in the order: soil > root > shoot > seed while in Zn it was soil > root > seed > shoot. Roots accumulated a larger fraction of soil Cu (70%) > Zn (67%) > Pb (54%). Bioaccumulation coefficient of soil to root ranged from 51-98 for Zn, 54-85 for Cu and 43-63 for Pb.Analysis of variance showed marginal change in bioaccumulation coefficient, noticed between plants (p > 0.05) while it varied significantly (p < 0.01) between tissues and metals. It increased from root to seed/fruit (root > shoot > seed/fruit) while decreased between metals from Zn to Pb (Zn > Cu > Pb). Out of the three, two Cu and Pb accumulated to phyotoxic levels while Zn was within threshold limit of phytotoxicity. PMID:22471223

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

    SciTech Connect

    Williams, B. L.; Phillips, L.; Major, J. D.; Durose, K.; Taylor, A. A.; Mendis, B. G.; Bowen, L.

    2014-02-03

    Radial p-n junction nanowire (NW) solar cells with high densities of CdTe NWs coated with indium tin oxide (ITO)/ZnO/CdS triple shells were grown with excellent heterointerfaces. The optical reflectance of the devices was lower than for equivalent planar films by a factor of 100. The best efficiency for the NW solar cells was η = 2.49%, with current transport being dominated by recombination, and the conversion efficiencies being limited by a back contact barrier (ϕ{sub B} = 0.52 eV) and low shunt resistances (R{sub SH} < 500 Ω·cm{sup 2})

  1. [Effects of adsorbents on partitioning of Cd and Pb in MSW incineration].

    PubMed

    Wu, Rong; Li, Qing-Hai; Meng, Ai-Hong; Zhang, Yan-Guo; Chen, Yong

    2009-07-15

    An incineration experiment using simulated municipal solid waste (MSW) in the tubular furnace was performed to study the effects of SiO2, Al2o3 and CaO on the partitioning of Cd and Pb under different operating conditions which included adsorbents percentage, furnace temperature and residence time. The results indicated that the increasing of SiO2, AL2O3, CaO concentration were favorable for Cd to partition in the bottom ash. And for Pb, SiO2 and Al2O3 had the same effects. However, the condition with CaO showed an opposite tendency of increasing Pb distribution in fly ash. While all of these adsorbents increasing, the effects were also enhanced. When the temperature of the tubular furnace was 850 degrees C, the adsorption efficiencies of these adsorbents for Cd were in the sequence of CaO > Al, O3 > SiO2, and for Pb, Al2O3 > SiO2 > CaO. In addition,with increasing of tubular furnace temperature and residence time, there would be more Cd and Pb compounds moving to the fly ash.

  2. Low-cost CdZnTe devices for cascade cell application

    SciTech Connect

    Basol, B.M.; Kapur, V.K. )

    1990-11-01

    This report describes a research program to develop a low-cost technique for producing Cd{sub 1-x}Zn{sub x}Te devices for cascade solar cell applications. The technique involves a two-stage process for fabricating such devices with a band gap of about 1.7 eV and a transparent contact layer of low-resistivity ZnTe. In the first stage, thin films of Cd, Zn, and Te are deposited in stacked layers as Cd{sub 1-x}An{sub x}Te. The second stage involves hearing and reacting the layers to form the compound. At first, electrodeposition was used for depositing the layers to successfully fabricate Dc{sub 1-x}Zn{sub x}Te thin-film devices. These films were also intrinsically doped with copper. For the first time, transparent ZnTe films of low resistivity were obtained in a two-stage process; preliminary solar cells using films with low Zn content were demonstrated. A second phase of the project involved growing films with higher Zn content (>15%). Such films were grown on CdS-coated substrates for fabricating devices. The effects of the solar-cell processing steps on the Cd{sub 1-x}Zn{sub x}Te and CdS/Cd{sub 1-x}Zn{sub x}Te interfaces were studied; results showed that the nature of the interface depended on the stoichiometry of the Cd{sub 1-x}Zn{sub x}Te thin film. A sharp interface was observed for the CdS/CdTe structures, but the interface became highly diffused as the Zn content in the absorber layer increased above 15%. The interaction between the CdS window layer and the Cd{sub 1-x}Zn{sub x}Te absorber layer was found to result from an exchange reaction between Zn in the absorber layer and the thin CdS film. 14 refs., 10 figs.

  3. [The impact of ZnS/CdS composite window layer on the quantun efficiency of CdTe solar cell in short wavelength].

    PubMed

    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.

  4. Accumulation and transport of Cd, Cu, and Pb in an estuarine salt marsh surface microlayer

    SciTech Connect

    Lion, L.W.; Leckie, J.O.

    1982-01-01

    Dissolved and particulate Cd, Cu, and Pb were measured in bulk solution and surface microlayer samples from an intertidal salt marsh in south San Francisco Bay. The phase distribution (dissolved vs. particulate) of metals was consistent with their calculated speciation in computer-simulated sea-salt matrices. Trace metal enrichment at the microlayer corresponded with physical events at the sample site. Advective exchange of Cd, Cu, and Pb between the estuary and marsh systems was dominated by transport of bulk suspended particulate metals, with an apparent net export from the marsh to the bay.

  5. Spin Dynamics of a Single Mn Ion in a CdTe/(Cd, Mg, Zn)Te Quantum Dot

    SciTech Connect

    Goryca, Mateusz; Kossacki, Piotr; Golnik, Andrzej; Kazimierczuk, Tomasz; Nawrocki, Michal; Wojnar, Piotr

    2010-01-04

    The spin dynamics of a single Mn ion confined in a CdTe/(Cd, Mg, Zn)Te quantum dot is determined by measurements of photon correlation of photoluminescence. The characteristic time of spin flip is a few nanoseconds and strongly depends on the excitation power.

  6. [Expression of adhesion molecules on CD34+ cells of BM and PB stem cell samples during high-dose chemotherapy combined with transplantation of autologous PB stem cells].

    PubMed

    Liu, Peng; Han, Xiao-Hong; Shi, Yuan-Kai; He, Xiao-Hui; Yang, Cheng; Ai, Bin

    2004-12-01

    This study was aimed to investigate the expressions of adhesion molecules such as CD54, CD49d and CD62L by CD34(+) cells sampled from different stages of bone marrow (BM) and peripheral blood (PB) before/after G-CSF mobilization and after transplantation through the direct labeling with three colour-immunofluorescence and flow cytometry, and to explore the differences in expression of adhesion molecules on CD34(+) cells from different origins and their clinical significance. Mononuclear cells collected from BM and PB before mobilization, after collection of stem cells and hematopoietic recostruction of BM at the end of transplantation were marked with CD54-FITC, CD49d-FITC and CD62L-FITC separately, as well as CD34-PE and CD45PerCE. 3-color fluorescene analysis was carried out by FACS. The expression differences of CD34(+) and adhesion molecules between BM and APBSC were compared. The results showed that expression differences of CD54, CD49d and cd62Lon CD34(+) cells belore mobilization, after collection and reconstraction of transplantation were not statiscally significant, the difference of CD54, CD49d and CD62L on CD34(+) between 1st and 2nd collections of hematopoietic stem cells also were not statiscally significant. In the collected APBSC, the expression level of CD34(+) CD49d(+) was significantly lower than those in BM before mobilization (P = 0.001). It is concluded that the method of chemotherapy combined with G-CSF mobilization can down-regulate CD49d expression in BM CD34(+) cells, thus can mobilize and move theirs into peripheral blood. After the reconstitution by transplantation, the expression of CD49d on CD34(+) cells tends to normal, the clinical significance needs to be elucidated by accumulation of much more cases.

  7. Size-dependent activation energy and carrier dynamics in Cd(x)Zn(1-x)Te/ZnTe quantum dots on Si substrates.

    PubMed

    Lee, Hong Seok

    2014-11-01

    We investigate the size-dependent activation energy and carrier dynamics in Cd(x)Zn(1-x)Te/ZnTe quantum dots (QDs) grown on Si substrates. The excitonic peak corresponding to transitions from the ground electronic subband to the ground heavy-hole band in Cd0.6Zn0.4Te/ZnTe QDs shifts to a lower energy with increasing Cd0.6Zn0.4Te thickness owing to an increase in the size of the QDs. The activation energy of the electrons confined in the Cd0.6Zn0.4Te/ZnTe QDs, as obtained from the temperature-dependent photoluminescence (PL) spectra, increases with increasing Cd0.6Zn0.4Te thickness owing to an enhancement of the quantum confinement effect resulting from an increase in the energy difference between the electronic state and the conduction band edge. The carrier dynamics of Cd0.6Zn0.4Te/ZnTe QDs is studied using time-resolved PL measurements, which shows a longer exciton lifetime for Cd0.6Zn0.4Te/ZnTe QDs with increasing Cd0.6Zn0.4Te thickness. This behavior is attributed to the reduction of the exciton oscillator strength resulting from a strong built-in electric field in the larger QDs.

  8. 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.

    PubMed

    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). PMID:21852741

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

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed

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

    2014-06-01

    This paper investigates the leaching potential of pervious concrete and its capacity for immobilizing Cu, Pb and Zn, which are common contaminants in urban runoff. Batch experiments showed that the leachability of Cu, Pb and Zn increased when pH<8. According to PHREEQC 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.

  11. Multi-terminal Two-color ZnCdSe/ZnCdMgSe Based Quantum-well Infrared Photodetector

    NASA Astrophysics Data System (ADS)

    Kaya, Yasin; Ravikumar, Arvind; Chen, Guopeng; Tamargo, Maria C.; Shen, Aidong; Gmachl, Claire

    Target recognition and identification applications benefits from two-color infrared (IR) detectors in the mid and long-wavelength IR regions. Currently, InGaAs/AlGaAs and GaAs/AlGaAs multiple quantum wells (QWs) grown on GaAs substrate are the most commonly used two-color QW IR photodetectors (QWIPs). However, the lattice-mismatch and the buildup of strain limit the number of QWs that can be grown, in turn increasing the dark current noise, and limiting the device detectivity.In this work, we report on two-color QWIPs based on the large conduction band offset (~1.12ev) ZnCdSe/ZnCdMgSe material system lattice matched to InP. QWIPs were designed based on a bound to quasi-bound transition, centered at 4 μm and 7 μm and each QW is repeated 50 times to eliminate the high dark current and a contact layer is inserted between the two stacks of QWs for independent electrical contacts. Wafers are processed into two step rectangular mesas by lithography and wet etching. Experiments showed absorption spectra centered at 4.9 μm and 7.6 μm at 80 K and the full width at half maximums were Δλ / λ = 21 % and Δλ / λ = 23 % , respectively. Current work studies the Johnson and the background noise limited detectivities of these QWIPs. Current address: School of Earth, Energy and Environmental Sciences, Stanford, CA 94305, USA.

  12. Charge transfer and optical properties of wurtzite-type ZnS/(CdS/ZnS){sub n} (n = 2, 4, 8) superlattices

    SciTech Connect

    Zeng, Xianghua Zhang, Wei; Cui, Jieya; Zhou, Min; Chen, Haitao

    2014-02-01

    Graphical abstract: (a) Normalized temperature-dependent PL spectra of ZnS/(CdS/ZnS){sub 4} superlattices from 5 to 300 K and (b) schematic of charge transfer at CdS/ZnS interface. - Highlights: • Wurtzite ZnS/(CdS/ZnS){sub n} superlattices were prepared at 100 °C by pulsed laser deposition. • Surface phonon of ZnS and multiple phonons modes of ZnS and CdS were observed. • The charge transfer of electrons from CdS electron to ZnS holes by excitation energy was found. - Abstract: ZnS/(CdS/ZnS){sub n} (n = 2, 4, 8) superlattices were deposited on sapphire substrate by pulsed laser deposition (PLD) with alternate cadmium sulfide (CdS) and zinc sulfide (ZnS) crystals at 100 °C. The prepared samples with an average thickness of ∼30 nm for ZnS layer and ∼60 nm for CdS layer have a wurtzite-type structure. Surface phonon of ZnS and multiple phonons modes for ZnS and CdS were observed from Raman spectra. PL spectra show a strong green emission at ∼496 nm, two weak emission bands at ∼400 and ∼577 nm, where the emission band at 400 nm was attributed to the recombination of surface defects states to valence, the emission band at 577 nm as the recombination of Cd{sub i}–V{sub Cd} centers, and the strong emission at ∼496 nm is from the charge transfer of electrons from CdS electron to ZnS holes by excitation energy.

  13. Efficient Z-scheme charge separation in novel vertically aligned ZnO/CdSSe nanotrees

    NASA Astrophysics Data System (ADS)

    Li, Zhengxin; Nieto-Pescador, Jesus; Carson, Alexander J.; Blake, Jolie C.; Gundlach, Lars

    2016-04-01

    A new tree-like ZnO/CdSSe nanocomposite with CdSSe branches grown on ZnO nanowires prepared via a two-step chemical vapor deposition is presented. The nanotrees (NTs) are vertically aligned on a substrate. The CdSSe branches result in strong visible light absorption and form a type-II heterojunction with the ZnO stem that facilitates efficient electron transfer. A combination of photoluminescence spectroscopy and lifetime measurements indicates that the NTs are promising materials for applications that benefit from a Z-scheme charge transfer mechanism. Vertically aligned branched ZnO nanowires can provide direct electron transport pathways to substrates and allow for efficient charge separation. These advantages of nanoscale hierarchical heterostructures make ZnO/CdSSe NTs a promising semiconductor material for solar cells, and other opto-electronic devices.

  14. CdZnTe Background Measurements at Balloon Altitudes with PoRTIA

    NASA Technical Reports Server (NTRS)

    Parsons, A.; Barthelmy, S.; Bartlett, L.; Gehrels, N.; Naya, J.; Stahle, C. M.; Tueller, J.; Teegarden, B.

    2003-01-01

    Measurements of the CdZnTe internal background at balloon altitudes are essential to determine which physical processes make the most important background contributions. We present results from CdZnTe background measurements made by PoRTIA, a small CdZnTe balloon instrument that was flown three times in three different shielding configurations. PoRTIA was passively shielded during its first flight from Palestine, Texas and actively shielded as a piggyback instrument on the GRIS balloon experiment during its second and third flights from Alice Springs, Australia, using the thick GRIS Nal anticoincidence shield. A significant CdZnTe background reduction was achieved during the third flight with PoRTIA placed completely inside the GRIS shield and blocking crystal, and thus completely surrounded by 15 cm of Nal. A unique balloon altitude background data set is provided by CdZnTe and Ge detectors simultaneously surrounded by the same thick anticoincidence shield; the presence of a single coxial Ge detector inside the shield next to PoRTIA allowed a measurement of the ambient neutron flux inside the shield throughout the flight. These neutrons interact with the detector material to produce isomeric states of the Cd, Zn and Te nuclei that radiatively decay; calculations are presented that indicate that these decays may explain most of the fully shielded CdZnTe background.

  15. A surface complexation and ion exchange model of Pb and Cd competitive sorption on natural soils

    NASA Astrophysics Data System (ADS)

    Serrano, Susana; O'Day, Peggy A.; Vlassopoulos, Dimitri; García-González, Maria Teresa; Garrido, Fernando

    2009-02-01

    The bioavailability and fate of heavy metals in the environment are often controlled by sorption reactions on the reactive surfaces of soil minerals. We have developed a non-electrostatic equilibrium model (NEM) with both surface complexation and ion exchange reactions to describe the sorption of Pb and Cd in single- and binary-metal systems over a range of pH and metal concentration. Mineralogical and exchange properties of three different acidic soils were used to constrain surface reactions in the model and to estimate surface densities for sorption sites, rather than treating them as adjustable parameters. Soil heterogeneity was modeled with >FeOH and >SOH functional groups, representing Fe- and Al-oxyhydroxide minerals and phyllosilicate clay mineral edge sites, and two ion exchange sites (X - and Y -), representing clay mineral exchange. An optimization process was carried out using the entire experimental sorption data set to determine the binding constants for Pb and Cd surface complexation and ion exchange reactions. Modeling results showed that the adsorption of Pb and Cd was distributed between ion exchange sites at low pH values and specific adsorption sites at higher pH values, mainly associated with >FeOH sites. Modeling results confirmed the greater tendency of Cd to be retained on exchange sites compared to Pb, which had a higher affinity than Cd for specific adsorption on >FeOH sites. Lead retention on >FeOH occurred at lower pH than for Cd, suggesting that Pb sorbs to surface hydroxyl groups at pH values at which Cd interacts only with exchange sites. The results from the binary system (both Pb and Cd present) showed that Cd retained in >FeOH sites decreased significantly in the presence of Pb, while the occupancy of Pb in these sites did not change in the presence of Cd. As a consequence of this competition, Cd was shifted to ion exchange sites, where it competes with Pb and possibly Ca (from the background electrolyte). Sorption on >SOH

  16. Recycled chitosan nanofibril as an effective Cu(II), Pb(II) and Cd(II) ionic chelating agent: adsorption and desorption performance.

    PubMed

    Liu, Dagang; Li, Zehui; Zhu, Yi; Li, Zhenxuan; Kumar, Rakesh

    2014-10-13

    Mechanically disassembled chitosan nanofibrils were prepared and used as metal ion chelating agents. Structure and morphology of nanofibrils were investigated and ionic adsorption or desorption performance were validated to establish related fitting models. In single metal ion solution, the saturated adsorption capacities of Cu(II), Pb(II), Cd(II), Zn(II), and Ni(II) were 168.66, 118.00 and 60.85, 143.67, and 63.32 mg/g, respectively. In ternary metal ion solution, Cu(II) was more competitive to be adsorbed than Pb(II) and Cd(II) and its removal could arrive at 60%. Ions adsorbed by nanofibrils could be released by EDTA and the recovery could keep above 70% after 3 sorption-desorption cycles. Hence, renewable and recyclable nanofibrillar chitosan exhibited a great promising application in metal treatments attributed to its high adsorption capacity and chelation efficiency.

  17. Air-Stable and Efficient PbSe Quantum-Dot Solar Cells Based upon ZnSe to PbSe Cation-Exchanged Quantum Dots.

    PubMed

    Kim, Sungwoo; Marshall, Ashley R; Kroupa, Daniel M; Miller, Elisa M; Luther, Joseph M; Jeong, Sohee; Beard, Matthew C

    2015-08-25

    We developed a single step, cation-exchange reaction that produces air-stable PbSe quantum dots (QDs) from ZnSe QDs and PbX2 (X = Cl, Br, or I) precursors. The resulting PbSe QDs are terminated with halide anions and contain residual Zn cations. We characterized the PbSe QDs using UV-vis-NIR absorption, photoluminescence quantum yield spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and transmission electron microscopy. Solar cells fabricated from these PbSe QDs obtained an overall best power conversion efficiency of 6.47% at one sun illumination. The solar cell performance without encapsulation remains unchanged for over 50 days in ambient conditions; and after 50 days, the National Renewable Energy Laboratory certification team certified the device at 5.9%.

  18. Development of electrodeposited ZnTe layers as window materials in ZnTe/CdTe/CdHgTe multi-layer solar cells

    SciTech Connect

    Islam, A.B.M.O. Chaure, N.B.; Wellings, J.; Tolan, G.; Dharmadasa, I.M.

    2009-02-15

    Zinc telluride (ZnTe) thin films have been deposited on glass/conducting glass substrates using a low-cost electrodeposition method. The resulting films have been characterized using various techniques in order to optimize growth parameters. X-ray diffraction (XRD) has been used to identify the phases present in the films. Photoelectrochemical (PEC) cell and optical absorption measurements have been performed to determine the electrical conductivity type, and the bandgap of the layers, respectively. It has been confirmed by XRD measurement that the deposited layers mainly consist of ZnTe phases. The PEC measurements indicate that the ZnTe layers are p-type in electrical conduction and optical absorption measurements show that their bandgap is in the range 2.10-2.20 eV. p-Type ZnTe window materials have been used in CdTe based solar cell structures, following new designs of graded bandgap multi-layer solar cells. The structures of FTO/ZnTe/CdTe/metal and FTO/ZnTe/CdTe/CdHgTe/metal have been investigated. The results are presented in this paper using observed experimental data.

  19. Nuclear reactor pulse calibration using a CdZnTe electro-optic radiation detector.

    PubMed

    Nelson, Kyle A; Geuther, Jeffrey A; Neihart, James L; Riedel, Todd A; Rojeski, Ronald A; Saddler, Jeffrey L; Schmidt, Aaron J; McGregor, Douglas S

    2012-07-01

    A CdZnTe electro-optic radiation detector was used to calibrate nuclear reactor pulses. The standard configuration of the Pockels cell has collimated light passing through an optically transparent CdZnTe crystal located between crossed polarizers. The transmitted light was focused onto an IR sensitive photodiode. Calibrations of reactor pulses were performed using the CdZnTe Pockels cell by measuring the change in the photodiode current, repeated 10 times for each set of reactor pulses, set between 1.00 and 2.50 dollars in 0.50 increments of reactivity.

  20. Photocatalysis on (CdS) x (ZnTe)1 - x solid solutions

    NASA Astrophysics Data System (ADS)

    Karpova, E. O.; Nagibina, I. Yu.; Makarova, A. S.

    2015-01-01

    Photocatalytic properties of the surface of binary compounds (CdS, ZnTe) and solid solutions (CdS) x (ZnTe)1 - x formed on their basis are studied by means of potentiometry and chromatography. The values of forbidden gap Δ E are calculated from the resulting UV spectra, according to which the components of the CdS-ZnTe system can display photocatalytic activity in the wavelength range of 364 to 670 nm. A scheme of a model setup for producing hydrogen from water is proposed using the authors' method.

  1. Possible Mesozoic age of Ellenville Zn-Pb-Cu(Ag) deposit, Shawangunk Mountains, New York

    USGS Publications Warehouse

    Friedman, J.D.; Conrad, J.E.; McKee, E.H.; Mutschler, F.E.; Zartman, R.E.

    1994-01-01

    Ore textures, epithermal open-space filling of Permian structures of the Alleghanian orogeny, and largely postorogenic mineralization of the Ellenville, New York, composite Zn-Pb-Cu(Ag) vein system, provide permissive evidence for post-Permian mineralization. Isochron ages determined by 40Ar/39Ar laser-fusion techniques for K-bearing liquid inclusions in main-stage quartz from the Ellenville deposit additionally suggest a Mesozoic time of mineralization, associated with extensional formation of the Newark basin. The best 40Ar/39Ar total-fusion age range is 165 ?? 30 to 193 ?? 35 Ma. The Mesozoic 40Ar/39Ar age agrees with that of many other dated northern Appalachian Zn-Pb-Cu(Ag) deposits with near-matching lead isotope ratios, and adds new evidence of Jurassic tectonism and mineralization as an overprint to Late Paleozoic tectonism at least as far north as Ellenville (lat. 41??43???N). ?? 1994 Springer-Verlag.

  2. Effects of Pb plus Cd mixtures on toxicity, and internal electrolyte and osmotic balance in the rainbow trout (Oncorhynchus mykiss).

    PubMed

    Clemow, Yvonne H; Wilkie, Michael P

    2015-04-01

    The physiological and toxicological effects of Cd and Pb have been thoroughly studied, but relatively little work has been done to determine how mixtures of these metals affect fishes in soft (<100 μmol L(-1)Ca(2+)) slightly acidic (pH ∼6) waters typical of many lakes in the Canadian Shield and other regions. Recently, it has been suggested that acute exposure to Cd plus Pb mixtures (3h) had greater than additive effects on both Ca(2+) and Na(+) influx, which could potentially exacerbate disturbances to ion balance and result in greater toxicity in rainbow trout (Oncorhynchus mykiss). The goal of the present study was to test this hypothesis by assessing the physiological and toxicological effects of Cd plus Pb mixtures over longer time periods (3-5 days), but at relatively low, more environmentally relevant concentrations of these metals. Accordingly, toxicity and measurements of blood acid-base regulation (PaO2, pHa), hematology (Ht, Hb, MCHC, and Protein), ionic composition (body ions and plasma Ca(2+), Na(+), Cl(-), osmolality), unidirectional Na(+) fluxes and branchial Na(+)/K(+)-ATPase activity were measured in rainbow trout exposed to Cd plus Pb mixtures. Experiments on rainbow trout, implanted with dorsal aortic catheters for repetitive blood sampling, demonstrated that exposure to Pb alone (26 nmol PbL(-1)) was less toxic than Cd alone (6 nmol CdL(-1)), which was much less toxic to the fish than a Cd plus Pb mixture (7 nmol CdL(-1) plus 45 nmol PbL(-1)), which led to greater than additive 80% mortality by 5d. Both Cd and Pb inhibited Na(+) influx over 3d exposure to the metals, which was partially offset by decreases in the diffusive efflux (outflux) of Na(+) across the gill. Despite an absence of detectable effects of Pb alone on plasma ion balance, Cd plus Pb mixtures exacerbated Cd-induced reductions in plasma Ca(2+) concentration, and resulted in pronounced reductions in plasma Na(+), Cl(-), and osmolality. No effects on Na(+)/K(+)-ATPase activity

  3. Effects of Pb plus Cd mixtures on toxicity, and internal electrolyte and osmotic balance in the rainbow trout (Oncorhynchus mykiss).

    PubMed

    Clemow, Yvonne H; Wilkie, Michael P

    2015-04-01

    The physiological and toxicological effects of Cd and Pb have been thoroughly studied, but relatively little work has been done to determine how mixtures of these metals affect fishes in soft (<100 μmol L(-1)Ca(2+)) slightly acidic (pH ∼6) waters typical of many lakes in the Canadian Shield and other regions. Recently, it has been suggested that acute exposure to Cd plus Pb mixtures (3h) had greater than additive effects on both Ca(2+) and Na(+) influx, which could potentially exacerbate disturbances to ion balance and result in greater toxicity in rainbow trout (Oncorhynchus mykiss). The goal of the present study was to test this hypothesis by assessing the physiological and toxicological effects of Cd plus Pb mixtures over longer time periods (3-5 days), but at relatively low, more environmentally relevant concentrations of these metals. Accordingly, toxicity and measurements of blood acid-base regulation (PaO2, pHa), hematology (Ht, Hb, MCHC, and Protein), ionic composition (body ions and plasma Ca(2+), Na(+), Cl(-), osmolality), unidirectional Na(+) fluxes and branchial Na(+)/K(+)-ATPase activity were measured in rainbow trout exposed to Cd plus Pb mixtures. Experiments on rainbow trout, implanted with dorsal aortic catheters for repetitive blood sampling, demonstrated that exposure to Pb alone (26 nmol PbL(-1)) was less toxic than Cd alone (6 nmol CdL(-1)), which was much less toxic to the fish than a Cd plus Pb mixture (7 nmol CdL(-1) plus 45 nmol PbL(-1)), which led to greater than additive 80% mortality by 5d. Both Cd and Pb inhibited Na(+) influx over 3d exposure to the metals, which was partially offset by decreases in the diffusive efflux (outflux) of Na(+) across the gill. Despite an absence of detectable effects of Pb alone on plasma ion balance, Cd plus Pb mixtures exacerbated Cd-induced reductions in plasma Ca(2+) concentration, and resulted in pronounced reductions in plasma Na(+), Cl(-), and osmolality. No effects on Na(+)/K(+)-ATPase activity

  4. Numerical study of the influence of ZnTe thickness on CdS/ZnTe solar cell performance

    NASA Astrophysics Data System (ADS)

    Skhouni, Othmane; El Manouni, Ahmed; Mari, Bernabe; Ullah, Hanif

    2016-05-01

    At present most of II-VI semiconductor based solar cells use the CdTe material as an absorber film. The simulation of its performance is realized by means of various numerical modelling programs. We have modelled a solar cell based on zinc telluride (ZnTe) thin film as absorber in substitution to the CdTe material, which contains the cadmium element known by its toxicity. The performance of such photovoltaic device has been numerically simulated and the thickness of the absorber layer has been optimized to give the optimal conversion efficiency. A photovoltaic device consisting of a ZnTe layer as absorber, CdS as the buffer layer and ZnO as a window layer was modelled through Solar Cell Capacitance Simulator Software. Dark and illuminated I-V characteristics and the results for different output parameters of ZnO/CdS/ZnTe solar cell were analyzed. The effect of ZnTe absorber thickness on different main working parameters such as: open-circuit voltage Voc, short-circuit current density Jsc, fill factor FF, photovoltaic conversion efficiency η was intensely studied in order to optimize ZnTe film thickness. This study reveals that increasing the thickness of ZnTe absorber layer results in higher efficiency until a maximum value and then decreases slightly. This maximum was found to be 10% at ZnTe optimum thickness close to 2 µm. Contribution to the topical issue "Materials for Energy Harvesting, Conversion and Storage (ICOME 2015) - Elected submissions", edited by Jean-Michel Nunzi, Rachid Bennacer and Mohammed El Ganaoui

  5. Occurrence of toxic metals (Hg, Cd and Pb) in fresh and canned tuna: public health implications.

    PubMed

    Storelli, Maria M; Barone, Grazia; Cuttone, Giuseppe; Giungato, Daniele; Garofalo, Rita

    2010-11-01

    Hg, Pb and Cd levels in fresh and canned tuna were determined and assessed by comparing element levels in these samples with maximum permissible limits set by European legislation. The estimated weekly intakes by human consuming both fresh and canned tuna were also evaluated for possible consumer health risks. Among tested metals, Hg had the highest concentrations, followed by Pb and Cd either in fresh tuna or canned tuna. None of the tested samples surpassed the European regulatory limits fixed for Cd and Pb, whereas 8.9% of the tuna cans and 20% of fresh tuna samples exceeded standard for Hg. The size of tuna was a determining factor of Hg burden. A high intake of Hg surpassing the toxicological reference value established by WHO, was associated with consumption of larger size tuna specimens. Also canned tuna consumption with Hg concentrations higher than 1 μg kg(-1), strongly increased the consumer exposure. In contrast, Cd and Pb weekly intakes through consumption either of fresh tuna or canned tuna did not exceed the toxicological reference values established by WHO, and consequently there was no human health risk. A continuous surveillance system of Hg content in these fishery products is crucial for consumer protection.

  6. Dynamics of Cd, Cu and Pb added to soil through different kinds of sewage sludge.

    PubMed

    Torri, S I; Lavado, R S

    2008-01-01

    A greenhouse experiment was set up to study the distribution of Cd, Cu and Pb in three typical soils of the Pampas Region amended with sewage sludge. A sequential extraction procedure was used to obtain four operationally defined geochemical species: exchangeable, bound to organic matter, bound to carbonates, and residual. Two kinds of sewage sludge were used: pure sewage sludge and sewage sludge containing 30% DM of its own incinerated ash, at rates equivalent to a field application of 150 t DM ha(-1). Pots were maintained at 80% of field capacity through daily irrigation with distilled water. Soil samples were obtained on days 1, 60, 270 and 360, and then air-dried and passed through a 2 mm sieve for analysis. Results showed that sludge application increased the less available forms of Cd, Cu and Pb. The inorganic forms became the most prevalent forms for Cu and Pb, whereas Cd was only found in the residual fraction. The concentrations of OM-Cu and INOR-Cu in the amended soil samples were closely correlated with soil pH, whereas the chemical behavior of Cd and Pb did not depend on soil physico-chemical characteristics.

  7. Occurrence of toxic metals (Hg, Cd and Pb) in fresh and canned tuna: public health implications.

    PubMed

    Storelli, Maria M; Barone, Grazia; Cuttone, Giuseppe; Giungato, Daniele; Garofalo, Rita

    2010-11-01

    Hg, Pb and Cd levels in fresh and canned tuna were determined and assessed by comparing element levels in these samples with maximum permissible limits set by European legislation. The estimated weekly intakes by human consuming both fresh and canned tuna were also evaluated for possible consumer health risks. Among tested metals, Hg had the highest concentrations, followed by Pb and Cd either in fresh tuna or canned tuna. None of the tested samples surpassed the European regulatory limits fixed for Cd and Pb, whereas 8.9% of the tuna cans and 20% of fresh tuna samples exceeded standard for Hg. The size of tuna was a determining factor of Hg burden. A high intake of Hg surpassing the toxicological reference value established by WHO, was associated with consumption of larger size tuna specimens. Also canned tuna consumption with Hg concentrations higher than 1 μg kg(-1), strongly increased the consumer exposure. In contrast, Cd and Pb weekly intakes through consumption either of fresh tuna or canned tuna did not exceed the toxicological reference values established by WHO, and consequently there was no human health risk. A continuous surveillance system of Hg content in these fishery products is crucial for consumer protection. PMID:20728500

  8. Removal of Cd, Cr, and Pb from aqueous solution by unmodified and modified agricultural wastes.

    PubMed

    Mahmood-Ul-Hassan, Muhammad; Suthor, Vishandas; Rafique, Ejaz; Yasin, Muhammad

    2015-02-01

    The adsorption of cadmium (Cd), chromium (Cr), and lead (Pb), widely detected in wastewater, by unmodified and modified banana stalks, corn cob, and sunflower achene was explored. The three agricultural wastes were chemically modified with sodium hydroxide (NaOH), in combination with nitric acid (HNO3) and sulfuric acid (H2SO4), in order to improve their adsorptive binding capacity. The experiments were conducted as a function of contact time and initial metal ion concentrations. Of the three waste materials, corn cob had the highest adsorptive capacity for Pb than Cr and Cd. The NaOH-modified substrates had higher adsorptive capacity than the acid modified samples. The chemical treatment invariably increased the adsorption capacity between 10 and 100 %. The Langmuir maximum sorption capacity (q m) of Pb was highest (21-60 mg g(-1) of banana, 30-57 mg g(-1) of corn cob, and 23-28 mg g(-1) of sunflower achene) and that of Cd was least (4-7 mg g(-1) of banana, 14-20 mg g(-1) of corn cob, and 11-16 mg g(-1) of sunflower achene). The q m was in the order of Pb > Cr > Cd for all the three adsorbents. The results demonstrate that the agricultural waste materials used in this study could be used to remediate water polluted with heavy metals. PMID:25626568

  9. Responses of membrane protection enzyme system of tobacco leaves on Hg, Cd and Pb stresses in soil.

    PubMed

    Yan, Chong Ling; Lin, Peng; Wang, Xiao Rong

    2002-09-01

    Pot experiment was used to study the responses of membrane protection enzyme system of tobacco leaves on Hg, Cd and Pb stresses in soil. The results showed that POD activity gradually increased with increasing concetrations of Hg, Cd and Pb. CAT and SOD activity gradually decreased under three heavy metals common existing and SOD variation curve showed unimodal curve under single or two elements existing with increase of concentration of Hg, Cd and Pb. The effects of Hg, Cd and Pb in soil: three elemets together > two elements together > single element only. The effects resulted in an imbalance--activated oxygen produce and scavenge and physiological biochemical process disorder. There was a synergistic action for the effect of Hg, Cd and Pb in soil on membrane protection enzyme system in tobacco leaves.

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

    PubMed

    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. PMID:26757944

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

    PubMed

    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.

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

    PubMed

    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. PMID:26478399

  13. Optical fiber amplifiers based on PbS/CdS QDs modified by polymers.

    PubMed

    Sun, Xiaolan; Xie, Libin; Zhou, Wei; Pang, Fufei; Wang, Tingyun; Kost, Alan R; An, Zesheng

    2013-04-01

    Optical fiber amplifiers based on PbS/CdS semiconductor quantum dots (QDs) modified by an amphiphilic polymer were demonstrated. Well-defined QDs and an amphiphilic copolymer were first prepared and the amphiphilic copolymer was then used to disperse the QDs into silica sol to allow uniform and reproducible incorporation of QDs into the silica coating of the optical fibers. QD-doped silica sol was deposited on the fusion tapered fiber coupler via dip-coating. A 1550 nm semiconductor light emitting diode as the signal source and a 980 nm laser diode as the pump source were injected into the fiber coupler simultaneously. Through evanescent wave excitation, a signal gain as high as 8 dB was obtained within the wavelength range between 1450 and 1650 nm. In addition, the optical fiber amplifiers based on PbS/CdS QDs showed enhanced thermal stability when compared to amplifiers based on PbS QDs.

  14. Solution grown PbS/CdS multilayer stacks as selective absorbers

    NASA Astrophysics Data System (ADS)

    Reddy, G. B.; Dutta, V.; Pandya, D. K.; Chopra, K. L.

    1981-08-01

    Theoretical and experimental studies are reported for the design and fabrication of multilayer stacks for selective solar absorbers (25 x 25 sq cm) of PbS and CdSm made on Ni coated Cu and stainless steel, using a solution grown technique. A mathematical model is formulated using the matrix multiplication method to calculate the reflectance of the absorbers. The preparation technique involves dissociating thiourea in an alkaline solution containing Pb or Cb salts, as reported by Sharma et al. (1976) and Kaur et al. (1980). The best values of solar absorptance and thermal emittance obtained are 0.92 and 0.12, respectively, which is in close agreement with the estimated values. Coatings with as many as six alternate layers of PbS and CdS have been made.

  15. Optical fiber amplifiers based on PbS/CdS QDs modified by polymers.

    PubMed

    Sun, Xiaolan; Xie, Libin; Zhou, Wei; Pang, Fufei; Wang, Tingyun; Kost, Alan R; An, Zesheng

    2013-04-01

    Optical fiber amplifiers based on PbS/CdS semiconductor quantum dots (QDs) modified by an amphiphilic polymer were demonstrated. Well-defined QDs and an amphiphilic copolymer were first prepared and the amphiphilic copolymer was then used to disperse the QDs into silica sol to allow uniform and reproducible incorporation of QDs into the silica coating of the optical fibers. QD-doped silica sol was deposited on the fusion tapered fiber coupler via dip-coating. A 1550 nm semiconductor light emitting diode as the signal source and a 980 nm laser diode as the pump source were injected into the fiber coupler simultaneously. Through evanescent wave excitation, a signal gain as high as 8 dB was obtained within the wavelength range between 1450 and 1650 nm. In addition, the optical fiber amplifiers based on PbS/CdS QDs showed enhanced thermal stability when compared to amplifiers based on PbS QDs. PMID:23571911

  16. Fractal structures in two-metal electrodeposition systems I: Pb and Zn

    SciTech Connect

    Nakouzi, Elias; Sultan, Rabih

    2011-12-15

    Pattern formation in two-metal electrochemical deposition has been scarcely explored in the chemical literature. In this paper, we report new experiments on zinc-lead fractal co-deposition. Electrodeposits are grown in special cells at a fixed large value of the zinc ion concentration, while that of the lead ion is increased gradually. A very wide diversity of morphologies are obtained and classified. Most of the deposited domains are almost exclusively Pb or Zn. But certain regions originating at the base cathode, ranging from a short grass alley to dense, grown-up bushes or shrubs, manifest a combined Pb-Zn composition. Composition is determined using scanning electron microscopy/energy dispersive x ray measurements as well atomic absorption spectroscopy. Pb domains are characterized by shiny leaf-like and dense deposits as well as flowers with round, balloon-like corollas. The Zn zones display a greater variety of morphologies such as thick trunks and thin and fine branching, in addition to minute ''cigar flower'' structures. The various morphologies are analyzed and classified from the viewpoint of fractal nature, characterized by the box-count fractal dimension. Finally, macroscopic spatial alternation between two different characteristic morphologies is observed under certain conditions.

  17. Determination of Zn, Pb, Cu, and Hg in soils of Ekpan, Nigeria

    SciTech Connect

    Omgbu, J.A.; Kokogho, M.A. )

    1993-01-01

    The concentrations of zinc, lead, copper, and mercury in solids in Ekpan were determined in order to assess the impact of petroleum-refining activities. Twenty soil samples were collected 100 m apart (10 topsoils 0 to 15 cm and 10 bottom soils 15 to 30 cm). Sample solutions prepared were analyzed using the atomic absorption spectrophotometry technique. Results show that top-soil samples contain as much as 7.13 to 13.10 [mu]g/g Zn, 55.13 to 65.50 [mu]g/g Pb, 3.47 to 5.27 [mu]g/g Cu, and 4.00 to 6.50 [mu]g.g Hg. Bottom soil samples contain as much as 7.17 to 13.77 [mu]g/g Zn, 54.97 to 63.23 [mu]g/g Pb, 3.57 to 6.50 [mu]/g Cu, and 4.57 to 6.63 [mu]g/g Hg. The levels reported had an abundance ratio in the order Pb > Zn > Hg > Cu in the soil samples. It is recommended that appropriate measures be put in place by the companies to treat waste effluent before discharging them to the immediate environment. 8 refs., 2 tabs.

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

    USGS Publications Warehouse

    Schardt, C.; Garven, G.; Kelley, K.D.; Leach, D.L.

    2008-01-01

    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). ?? Springer-Verlag 2008.

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

    NASA Astrophysics Data System (ADS)

    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).

  20. Li-Zn-Pb multi isotopic characterization of the Loire River Basin, France

    NASA Astrophysics Data System (ADS)

    Millot, R.; Desaulty, A.; Widory, D.; Bourrain, X.

    2013-12-01

    The Loire River in France is approximately 1010 km long and drains an area of 117 800 km2. Upstream, the Loire River flows following a south to north direction from the Massif Central down to the city of Orléans, 650 km from its source. The Loire River is one of the main European riverine inputs to the Atlantic Ocean. Over time, its basin has been exposed to numerous sources of anthropogenic metal pollutions, such as metal mining, industry, agriculture and domestic inputs. The Loire River basin is thus an excellent study site to develop new isotope systematics for tracking anthropogenic sources of metal pollutions (Zn and Pb) and also to investigate Li isotope tracing that can provide key information on the nature of weathering processes at the Loire River Basin scale. Preliminary data show that Li-Zn-Pb concentrations and isotopic compositions span a wide range in river waters of the Loire River main stream and the main tributaries. There is a clear contrast between the headwaters upstream and rivers located downstream in the lowlands. In addition, one of the major tributaries within the Massif Central (the Allier River) is clearly influenced by inputs resulting from mineralizations and thermomineral waters. The results showed that, on their own, each of these isotope systematics reveals important information about the geogenic or anthropogenic origin Li-Zn-Pb. Considered together, they are however providing a more integrated understanding of the overall budgets of these elements at the scale of the Loire River Basin.

  1. Fast evolution of tropospheric Pb- and Zn-rich particles in the vicinity of a lead smelter

    NASA Astrophysics Data System (ADS)

    Choël, M.; Deboudt, K.; Flament, P.; Lecornet, G.; Perdrix, E.; Sobanska, S.

    Dusts collected on air filters at a Pb-Zn refinery located in northern France were sampled in 1997, 1999 and 2002. The low temporal variability in major elements (Pb, Zn and S) abundances suggested chemical composition of particulate emissions was stable over time. In July 2001 and March 2002, atmospheric aerosols were sampled in the vicinity of the Pb-Zn refinery upwind and downwind from the smelters. Bulk concentrations of major elements (Al, Fe, Pb and Zn) and hydrosoluble ions (Na +, NH 4+, Mg 2+, K +, Ca 2+, Cl - NO 3- and SO 42-) were, respectively, determined by atomic absorption spectrometry and ion chromatography. Elemental and molecular individual particle analyses were, respectively, performed by automated SEM-EDX and Raman microspectrometry. Continental air masses (campaign 2001) were characterized by low Na + and high SO 42-, NO 3- and NH 4+ contents upwind from the smelters. Individual particle analysis of Pb- and Zn-rich airborne particles collected downwind from the refinery indicated elemental associations and molecular speciation were similar to those obtained at the emission: Pb compounds were mainly identified as oxides, sulfates and oxy-sulfates whereas Zn compounds were identified as sulfides. Marine air masses (campaign 2002) were characterized by high Na + contents upwind from the smelters. Individual particle analysis of Pb- and Zn-rich particles collected downwind from the refinery pointed out a systematic association with Na, not emitted by the refinery, suggesting internal mixing of marine aerosols with heavy-metals dusts emitted by the refinery. Such fast evolution of airborne particles chemical composition in the vicinity of the refinery was further proven by SEM-EDX and Raman microspectrometry mappings showing physical evolution by aggregation or coagulation of Zn- and Pb-rich particles with aged sea-salts.

  2. Analytical bond-order potential for the Cd-Zn-Te ternary system

    NASA Astrophysics Data System (ADS)

    Ward, D. K.; Zhou, X. W.; Wong, B. M.; Doty, F. P.; Zimmerman, J. A.

    2012-12-01

    Cd-Zn-Te ternary alloyed semiconductor compounds are key materials in radiation detection and photovoltaic applications. Currently, crystalline defects such as dislocations limit the performance of these materials. Atomistic simulations are a powerful method for exploring crystalline defects at a resolution unattainable by experimental techniques. To enable accurate atomistic simulations of defects in the Cd-Zn-Te systems, we develop a full Cd-Zn-Te ternary bond-order potential. This Cd-Zn-Te potential has numerous unique advantages over other potential formulations: (1) It is analytically derived from quantum mechanical theories and is therefore more likely to be transferable to environments that are not explicitly tested. (2) A variety of elemental and compound configurations (with coordination varying from 1 to 12) including small clusters, bulk lattices, defects, and surfaces are explicitly considered during parameterization. As a result, the potential captures structural and property trends close to those seen in experiments and quantum mechanical calculations and provides a good description of melting temperature, defect characteristics, and surface reconstructions. (3) Most importantly, this potential is validated to correctly predict the crystalline growth of the ground-state structures for Cd, Zn, Te elements as well as CdTe, ZnTe, and Cd1-xZnxTe compounds during highly challenging molecular dynamics vapor deposition simulations.

  3. The Adsorption and Desorption of Pb(2+) and Cd(2+) in Freeze-Thaw Treated Soils.

    PubMed

    Li, Linhui; Ma, Jincai; Xu, Meng; Li, Xu; Tao, Jiahui; Wang, Guanzhu; Yu, Jitong; Guo, Ping

    2016-01-01

    Adsorption and desorption are important processes that influence the potential toxicity and bioavailability of heavy metals in soils. However, information regarding adsorption and desorption behavior of heavy metals in soils subjected to freeze-thaw cycles is poorly understood. In the current study, the effect of freeze-thaw cycles with different freezing temperature (-15, -25, -35°C) on soil properties was investigated. Then the adsorption and desorption behavior of Pb(2+) and Cd(2+) in freeze-thaw treated soils was studied. The adsorption amounts of Pb(2+) and Cd(2+) in freeze-thaw treated soils were smaller than those in unfrozen soils (p < 0.05), due to the fact that pH, cation exchange capacity, organic matter content, free iron oxide content, and CaCO3 content in freeze-thaw treated soils were smaller than those in unfrozen soils. The adsorption amounts of Pb(2+) and Cd(2+) in soils treated with lower freezing temperatures were higher than those in soils treated with higher freezing temperatures. Desorption percentages of Pb(2+) and Cd(2+) in unfrozen soils were smaller than those in freeze-thaw treated soils (p < 0.05). The desorption percentages of Pb(2+) and Cd(2+) were smaller in soils treated with lower freezing temperatures than those in soils treated with higher freezing temperatures. The results obtained highlight the change of the adsorption and desorption behavior of typical heavy metals in freeze-thaw treated soils located in seasonal frozen soils zone in northeast China.

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

    PubMed

    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. PMID:26477581

  5. Invariant bandwidth of erbium in ZnO-PbO-tellurite glasses: Local probe/model

    SciTech Connect

    Ramamoorthy, Raj Kumar; Bhatnagar, Anil K.

    2014-04-24

    A series of [(70TeO{sub 2}−(30−x)ZnO−xPbO){sub 0.99}−(Er{sub 2}O{sub 3}){sub 0.01}; where x = 5, 10, 15 and 20] tellurite glasses, were prepared using the melt quenching technique. Crucial emission bandwidth of erbium at 1.5 μm has been derived and found to be the same for all the glasses, irrespective of PbO content. This identical bandwidth in all tellurite glasses is attributed to the presence of erbium in tellurium rich disordered environments. This result has been complemented through XANES spectra and the obtained invariant first shell of 6.5 oxygen atoms, confirm the unchanged environment in these glasses for all PbO content.

  6. Photosensitization of ZnO Crystals with Iodide-Capped PbSe Quantum Dots.

    PubMed

    King, Laurie A; Parkinson, B A

    2016-07-21

    Lead selenide (PbSe) quantum dots (QDs) are an attractive material for application in photovoltaic devices due to the ability to tune their band gap, efficient multiple exciton generation, and high extinction coefficients. However, PbSe QDs are quite unstable to oxidation in air. Recently there have been multiple studies detailing postsynthetic halide treatments to stabilize lead chalcogenide QDs. We exploit iodide-stabilized PbSe QDs in a model QD-sensitized solar cell configuration where zinc oxide (ZnO) single crystals are sensitized using cysteine as a bifunctional linker molecule. Sensitized photocurrents stable for >1 h can be measured in aqueous KI electrolyte that is usually corrosive to QDs under illumination. The spectral response of the sensitization extended out to 1700 nm, the farthest into the infrared yet observed. Hints of the existence of multiple exciton generation and collection as photocurrent, as would be expected in this system, are speculated and discussed. PMID:27398873

  7. ``Flash'' synthesis of ``giant'' Mn-doped CdS/ZnSe/ZnS nanocrystals with ZnSe layer as hole quantum-well

    NASA Astrophysics Data System (ADS)

    Xu, Ruilin; Zhang, Jiayu

    Usually, exciton-Mn energy transfer in Mn-doped CdS/ZnS nanocrystals (NCs) can readily outcompete the exciton trapping by an order of magnitude. However, with the accumulation of non-radiative defects in the giant shell during the rapid growth of the thick shell (up to ~20 monolayers in no more than 10 minutes), the photoluminescence (PL) quantum yield of this kind of ``giant'' NCs is significantly reduced by the accumulation of non-radiative defects during the rapid growth of thick shell. That is because the exciton-Mn energy transfer in Mn-doped CdS/ZnS NCs is significantly inhibited by the hole trapping as the major competing process, resulting from the insufficient hole-confinement in CdS/ZnS NCs. Accordingly ``flash'' synthesis of giant Mn-doped CdS/ZnSe/ZnS NCs with ZnSe layer as hole quantum-well is developed to suppress the inhibition. Meanwhile Mn2+ PL peak changes profoundly from ~620 nm to ~540 nm after addition of ZnSe layer. Studies are under the way to explore the relevant mechanisms.

  8. Low temperature solution-phase growth of ZnSe and ZnSe/CdSe core/shell nanowires.

    PubMed

    Petchsang, Nattasamon; Shapoval, Liubov; Vietmeyer, Felix; Yu, Yanghai; Hodak, Jose H; Tang, I-Ming; Kosel, Thomas H; Kuno, Masaru

    2011-08-01

    High quality ZnSe nanowires (NWs) and complementary ZnSe/CdSe core/shell species have been synthesized using a recently developed solution-liquid-solid (SLS) growth technique. In particular, bismuth salts as opposed to pre-synthesized Bi or Au/Bi nanoparticles have been used to grow NWs at low temperatures in solution. Resulting wires are characterized using transmission electron microscopy and possess mean ensemble diameters between 15 and 28 nm with accompanying lengths ranging from 4-10 μm. Subsequent solution-based overcoating chemistry results in ZnSe wires covered with CdSe nanocrystals. By varying the shell's growth time, different thicknesses can be obtained and range from 8 to 21 nm. More interestingly, the mean constituent CdSe nanocrystal diameter can be varied and results in size-dependent shell emission spectra.

  9. Extended defects in as-grown CdZnTe

    SciTech Connect

    Xu, L.; Bolotnikov, A.E.; Hossain, A.; Kim, K-H.; Gul, R.; Yang, G.; Camarda, G.S.; Marchini, L.; Cui, Y.; James, R.B.; Xu, Y.; Wang, T.; Jie, W.

    2010-08-01

    We characterized samples cut from different locations in as-grown CdZnTe (CZT) ingots, using Automated Infrared (IR) Transmission Microscopy and White Beam X-ray Diffraction Topography (WBXDT), to locate and identify the extended defects in them. Our goal was to define the distribution of these defects throughout the entire ingot and their effects on detectors’ performance as revealed by the pulse-height spectrum. We found the highest- and the lowest- concentration of Te inclusions, respectively, in the head and middle part of the ingot, which could serve as guidance in selecting samples. Crystals with high concentration of Te inclusions showed high leakage current and poor performance, because the accumulated charge loss around trapping centers associated with Te inclusions distorts the internal electric field, affects the carrier transport properties inside the crystal, and finally degrades the detector’s performance. In addition, other extended defects revealed by the WBXDT measurements severely reduced the detector’s performance, since they trap large numbers of electrons, leading to a low signal for the pulse-height spectrum, or none whatsoever. Finally, we fully correlated the detector’s performance with our information on the extended defects gained from both the IR- and the WBXDT-measurements.

  10. Pb(II)-promoted amide cleavage: mechanistic comparison to a Zn(II) analogue.

    PubMed

    Elton, Eric S; Zhang, Tingting; Prabhakar, Rajeev; Arif, Atta M; Berreau, Lisa M

    2013-10-01

    Two new Pb(II) complexes of the amide-appended nitrogen/sulfur epppa (N-((2-ethylthio)ethyl)-N-((6-pivaloylamido-2-pyridyl)methyl)-N-((2-pyridyl)methyl)amine) chelate ligand, [(epppa)Pb(NO3)2] (4-NO3) and [(epppa)Pb(ClO4)2] (4-ClO4), were prepared and characterized. In the solid state, 4-NO3 exhibits κ(5)-epppa chelate ligand coordination as well as the coordination of two bidentate nitrate ions. In acetonitrile, 4-NO3 is a 1:1 electrolyte with a coordinated NO3(-), whereas 4-ClO4 is a 1:2 electrolyte. Treatment of 4-ClO4 with 1 equiv Me4NOH·5H2O in CH3CN:CH3OH (3:5) results in amide methanolysis in a reaction that is akin to that previously reported for the Zn(II) analogue [(epppa)Zn](ClO4)2 (3-ClO4). (1)H NMR kinetic studies of the amide methanolysis reactions of 4-ClO4 and 3-ClO4 as a function of temperature revealed free energies of activation of 21.3 and 24.5 kcal/mol, respectively. The amide methanolysis reactions of 4-ClO4 and 3-ClO4 differ in terms of the effect of the concentration of methanol (saturation kinetics for 4-ClO4; second-order behavior for 3-ClO4), the observation of a small solvent kinetic isotope effect (SKIE) only for the reaction of the Zn(II)-containing 3-ClO4, and the properties of an initial intermediate isolated from each reaction upon treatment with Me4NOH·5H2O. These experimental results, combined with computational studies of the amide methanolysis reaction pathways of 4-ClO4 and 3-ClO4, indicate that the Zn(II)-containing 3-ClO4 initially undergoes amide deprotonation upon treatment with Me4NOH·5H2O. Subsequent amide protonation from coordinated methanol yields a structure containing a coordinated neutral amide and methoxide anion from which amide cleavage can then proceed. The rate-determining step in this pathway is either amide protonation or protonation of the leaving group. The Pb(II)-containing 4-ClO4 instead directly forms a neutral amide-containing, epppa-ligated Pb(II)-OH/Pb(II)-OCH3 equilibrium mixture upon treatment

  11. Comparative effects of Cd and Pb on biochemical response and DNA damage in the earthworm Eisenia fetida (Annelida, Oligochaeta).

    PubMed

    Li, Mei; Liu, Zhengtao; Xu, Yun; Cui, Yibin; Li, Dingsheng; Kong, Zhiming

    2009-02-01

    There are rising concerns about the hazardous effects of cadmium (Cd) and lead (Pb) on the environment in China. Biochemical and comet assays were conducted on the earthworm Eisenia fetida, a suitable bio-indicator organism for evaluating soil pollution after exposure to two heavy metals, Cd and Pb. Protein content increased at low Cd concentrations (p<0.05) and decreased at the highest concentration of 10 mg kg(-1), compared to control (p<0.05). Pb showed an inhibitory effect on protein content at low concentrations but demonstrated no significant effect at higher concentrations. There were no significant differences between control and treated groups at the doses of 1 and 10 mg kg(-1) Cd while at a dose of 0.1 mg kg(-1) Cd the cellulase activity was significantly increased compared to control. Cellulase activities of Pb-treated E. fetida increased in a dose dependent fashion. Results of the comet assay indicated toxicant induced DNA damage. Cd exposure caused significant differences between control and treatment groups (ANOVA, p< 0.05, p< 0.01) and a positive dose-response profile. As for Pb treatment, there were no significant differences between the groups treated with 50 and 500 mg kg(-1) of Pb and the control. Results showed that DNA damage from Cd was more serious than that from Pb. And this indicated that the earthworm was more sensitive to the effects of Cd.

  12. Unseeded growth of CdZnTe:In by THM technique

    NASA Astrophysics Data System (ADS)

    Roy, Utpal N.; Weiller, Stephen; Stein, Juergen; Gueorguiev, Andrey

    2009-08-01

    Travelling heater method (THM) has been a great success lately for the growth of large CdZnTe crystals. In this presentation, indium doped CdZnTe crystals have been grown adapting travelling heater method (THM) in vertical configuration, using three zone custom designed muffle furnace. Crystals have been grown with different ampoule diameter and size to study the grain growth. Seedless single crystalline CdZnTe:In crystals have been gown with 4 cm diameter weighing about 650 grams. Crystals have been characterized by near IR imaging, both microscopic and full wafer. The average resistivity along the length of the ingot was found to be about 109 ohm-cm. A resolution 3.2% was obtained at 662 keV. The effect of annealing of the whole wafer in Cd-Zn alloyed vapor on the resistivity and on the Te precipitations will be discussed.

  13. Low temperature solution-phase growth of ZnSe and ZnSe/CdSe core/shell nanowires

    NASA Astrophysics Data System (ADS)

    Petchsang, Nattasamon; Shapoval, Liubov; Vietmeyer, Felix; Yu, Yanghai; Hodak, Jose H.; Tang, I.-Ming; Kosel, Thomas H.; Kuno, Masaru

    2011-08-01

    High quality ZnSe nanowires (NWs) and complementary ZnSe/CdSe core/shell species have been synthesized using a recently developed solution-liquid-solid (SLS) growth technique. In particular, bismuth salts as opposed to pre-synthesized Bi or Au/Bi nanoparticles have been used to grow NWs at low temperatures in solution. Resulting wires are characterized using transmission electron microscopy and possess mean ensemble diameters between 15 and 28 nm with accompanying lengths ranging from 4-10 μm. Subsequent solution-based overcoating chemistry results in ZnSe wires covered with CdSe nanocrystals. By varying the shell's growth time, different thicknesses can be obtained and range from 8 to 21 nm. More interestingly, the mean constituent CdSe nanocrystal diameter can be varied and results in size-dependent shell emission spectra.High quality ZnSe nanowires (NWs) and complementary ZnSe/CdSe core/shell species have been synthesized using a recently developed solution-liquid-solid (SLS) growth technique. In particular, bismuth salts as opposed to pre-synthesized Bi or Au/Bi nanoparticles have been used to grow NWs at low temperatures in solution. Resulting wires are characterized using transmission electron microscopy and possess mean ensemble diameters between 15 and 28 nm with accompanying lengths ranging from 4-10 μm. Subsequent solution-based overcoating chemistry results in ZnSe wires covered with CdSe nanocrystals. By varying the shell's growth time, different thicknesses can be obtained and range from 8 to 21 nm. More interestingly, the mean constituent CdSe nanocrystal diameter can be varied and results in size-dependent shell emission spectra. Electronic supplementary information (ESI) available. See DOI: 10.1039/c1nr10176e

  14. First-Principles Study on Cd Doping in Cu2ZnSnS4 and Cu2ZnSnSe4

    NASA Astrophysics Data System (ADS)

    Maeda, Tsuyoshi; Nakamura, Satoshi; Wada, Takahiro

    2012-10-01

    To quantitatively evaluate the substitution energies of Cd atom for Cu, Zn, or Sn atom in indium-free photovoltaic semiconductors Cu2ZnSnS4 (CZTS) and Cu2ZnSnSe4 (CZTSe), first-principles pseudopotential calculations using plane-wave basis functions were performed. The substitution energies of Cd atom in kesterite-type CZTS and CZTSe were calculated in consideration of the atomic chemical potentials of the constituent elements of Cu, Zn, Sn, and the doping atom of Cd. During the chemical bath deposition (CBD) of the CdS layer on the CZTS or CZTSe layer, Cu, Zn, and Cd atoms dissolved in the ammonia aqueous solution and formed [Cu(NH3)2]+, [Zn(NH3)4]2+, and [Cd(NH3)4]2+ complex ions. Therefore, the chemical potentials of Cu, Zn, and Cd atoms in [Cu(NH3)2]+, [Zn(NH3)4]2+, and [Cd(NH3)4]2+ complex ions were calculated. We found that the substitution energies of n-type CdCu and charge-neutral CdZn in CZTS and CZTSe are smaller than that of p-type CdSn. The substitution energies of CdCu in CZTS and CZTSe are smaller than that in chalcopyrite-type CuInSe2 (CIS). However, the substitution energies of CdCu, CdZn, and CdSn are positive values. The formation energy of charge-neutral Cd doping with the Cu vacancy (CdCu + VCu) pair is a negative value and greatly smaller than those of donor-type CdCu and neutral CdZn in CZTS and CZTSe. These results indicate that the charge-neutral (CdCu + VCu) vacancy pair is easily formed during the CBD of the CdS layer on the CZTS or CZTSe layer. A small amount of n-type CdCu and neutral CdZn would also be formed.

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

    NASA Astrophysics Data System (ADS)

    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

  16. Environmental geochemistry of shale-hosted Ag-Pb-Zn massive sulfide deposits in northwest Alaska: Natural background concentrations of metals in water from mineralized areas

    USGS Publications Warehouse

    Kelley, K.D.; Taylor, C.D.

    1997-01-01

    Red Dog, Lik and Drenchwater are shale-hosted stratiform Ag-Pb-Zn massive sulfide deposits in the northwestern Brooks Range. Natural background concentrations of metals in waters from the undisturbed (unmined) Drenchwater prospect and Lik deposit were compared to pre-mining baseline studies conducted at Red Dog. The primary factors affecting water chemistry are the extent of exposure of the deposits, the grade of mineralization, the presence of carbonate reeks in the section, and the proportion of Fe-sulfide in the ore. Surface water samples from the Drenchwater prospect, which has pyrite-dominant mineralization exposed in outcrop, have pH values as low as 2.8 and high dissolved concentrations of metals including as much as 95 mg 1-1 Al, 270 mg 1-1 Fe, 8 ??1-1 Cd, 10 ??1-1 Pb, and 2600 ??1-1 Zn, with As up to 26 ??g1-1. Surface waters from the Red Dog deposit prior to mining were also acidic and metal-rich, however, dissolved metal concentrations in Red Dog waters were many times greater. The higher metal concentrations in Red Dog waters reflect the high Zn grades and the abundant sphalerite, pyrite, and galena that were present in outcrop prior to mining. In contrast, despite significant mineralization at the Lik deposit, carbonate rocks in the section buffer the system, resulting in less acidic, mostly near-neutral pH values with low concentrations of most metals except Zn.

  17. Properties of a CdZnO/ZnO multiple quantum-well light-emitting diode

    NASA Astrophysics Data System (ADS)

    Liu, Zhan-Hui; Zhang, Li-Li; Li, Qing-Fang; Zhang, Rong; Xie, Zi-Li; Xiu, Xiang-Qian; Liu, Bin

    2016-10-01

    A CdZnO/ZnO multiple quantum-well light-emitting diode (LED) structure was successfully grown by using plasma-assisted molecular beam epitaxy on a p-GaN template that had been grown by using metal-organic chemical-vapor deposition on a c-sapphire substrate. The properties of the sample were characterized by using high-resolution X-ray diffraction, transmission electron microscopy, and temperature-dependent photoluminescence measurements. The light output performance of the CdZnO/ZnO QW LED device was also investigated in detail by using I-V and electroluminescence spectral measurements. The characterization showed that our CdZnO/ZnO QW LED structure had good crystalline quality and weaker carrier localization. Owing to the heterojunction structure, the I-V curve indicated that the LED device had a higher turn-on voltage and series resistance. The EL measurement demonstrated that for our LED device's optoelectronic characteristic, the carrier-screening effect played the dominant role in the emission-energy blue-shift mechanism, and the broadening of the emission energy width was mainly ascribed to the band-filling effect. Without a special heat sinking, the L-I curve exhibited slight efficiency droop after 30 mA.

  18. Purification, growth, and characterization of Zn(x)Cd(1-x)Se crystals

    NASA Technical Reports Server (NTRS)

    Silberman, E.; Burger, A.; Chen, W.; Henderson, D. O.; Morgan, S. H.; Springer, John M.; Yao, Y.

    1989-01-01

    The purification of starting materials which were used in the growth of Zn(x)Cd(1-x)Se (x = 0.2) single crystals using the traveling solution method (TSM) is reported. Up to 13 cm long single crystals and as grown resistivities of 6 x 10(exp 12) ohm/cm could be achieved. Infrared and Raman spectra of Zn(0.2)Cd(0.8)Se are also presented and discussed.

  19. A Diffusive Gradient-in-Thin-Film Technique for Evaluation of the Bioavailability of Cd in Soil Contaminated with Cd and Pb

    PubMed Central

    Wang, Peifang; Wang, Teng; Yao, Yu; Wang, Chao; Liu, Cui; Yuan, Ye

    2016-01-01

    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. PMID:27271644

  20. A Diffusive Gradient-in-Thin-Film Technique for Evaluation of the Bioavailability of Cd in Soil Contaminated with Cd and Pb.

    PubMed

    Wang, Peifang; Wang, Teng; Yao, Yu; Wang, Chao; Liu, Cui; Yuan, Ye

    2016-06-02

    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.

  1. The Response of Metallothionein and Malondialdehyde after Exclusive and Combined Cd/Zn Exposure in the Crab Sinopotamon henanense

    PubMed Central

    Li, Yingjun; Chai, Xi; Wu, Hao; Jing, Weixin; Wang, Lan

    2013-01-01

    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. PMID:24260400

  2. Growth of high performance piezoelectric crystal Pb(Zn1/3Nb2/3)O3-PbTiO3 using PbO flux.

    PubMed

    Jin, Min; Xu, Jiayue; Shi, Minli; Wu, Xianjun; Tong, Jian

    2007-05-01

    Novel piezoelectric crystal (1-x)Pb(Zn(1/3)Nb(2/3))O(3)-xPbTiO(3) (PZNT) has attracted much attention due to its high piezoelectric properties and potential applications in medical ultrasonic devices, sonar transducers, solid state actuators. However, the applications of PZNT crystals are limited by the lack of a simple and reproducible growth technique. In this work, large size PZNT crystals were grown by the vertical Bridgman method using 50 mol% PbO as a flux. The growth conditions were optimized as mole ratio of raw materials and flux=1:1, soaking temperature 1150-1200 degrees C, soaking time 10 h, the lowering rate of the crucible 0.5 mm/h and the temperature gradient near solid-liquid interface about 50 degrees C/mm. The maximum size of as-grown PZNT crystal was about 60 mm in length. The crystal was oriented and its piezoelectric constant d(33) and coupling coefficient k(33) were measured over 2000pC/N and 0.92, respectively.

  3. Structural and opto-electrical properties of pyrolized ZnO—CdO crystalline thin films

    NASA Astrophysics Data System (ADS)

    Tanveer Karim, A. M. M.; Khan, M. K. R.; Mozibur Rahman, M.

    2015-05-01

    A series of ZnO—CdO thin films of different molar ratios of Zn and Cd have been deposited on glass substrate at substrate temperature ˜360 °C by the spray pyrolysis technique at an ambient atmosphere. X-ray diffraction (XRD) studies confirmed the polycrystalline nature of the film and modulated crystal structures of wurtzite (ZnO) and cubic (CdO) are formed. The evaluated lattice parameters, and crystallite size are consistent with literature. Dislocation density and strain increased in the film as the grain sizes of ZnO and CdO are decreased. The band gap energy varies from 3.20 to 2.21 eV depending on the Zn/Cd ratios in the film. An incident photon intensity dependent I-V study confirmed that the films are highly photosensitive. Current increased with the increase of the intensity of the light beam. The optical conductivity and the optical constants, such as extinction coefficient, refractive index and complex dielectric constants are evaluated from transmittance and reflectance spectra of the films and these parameters are found to be sensitive to photon energy and displayed intermediate optical properties between ZnO and CdO, making it preferable for applications as the buffer and window layers in solar cells.

  4. Calcium uptake in aquatic insects: influences of phylogeny and metals (Cd and Zn).

    PubMed

    Poteat, Monica D; Buchwalter, David B

    2014-04-01

    Calcium sequestration in the hypo-osmotic freshwater environment is imperative in maintaining calcium homeostasis in freshwater aquatic organisms. This uptake process is reported to have the unintended consequence of potentially toxic heavy metal (Cd, Zn) uptake in a variety of aquatic species. However, calcium uptake remains poorly understood in aquatic insects, the dominant invertebrate faunal group in most freshwater ecosystems. Here, we examined Ca uptake and interactions with heavy metals (Cd, Zn) at low ambient Ca levels (12.5 μmol l(-1)) in 12 aquatic insect species within Ephemerellidae (mayfly) and Hydropsychidae (caddisfly), two families differentially responsive to trace metal pollution. We found Ca uptake varied 70-fold across the 12 species studied. Body mass and clade (family) were found to significantly influence both Ca uptake and adsorption (P≤0.05). Zn and Cd uptake rate constants (ku) exhibited a strong correlation (r=0.96, P<0.0001), suggesting a shared transport system. Ca uptake failed to significantly correlate with either Zn or Cd ku values. Further, neither Zn nor Cd exhibited inhibitory effects toward Ca uptake. In fact, we saw evidence of modest stimulation of Ca uptake rates in some metal treatments. This work suggests that insects generally differ from other freshwater taxa in that aqueous Ca uptake does not appear to be compromised by Cd or Zn exposure. It is important to understand the trace metal and major ion physiology of aquatic insects because of their ecological importance and widespread use as ecological indicators.

  5. Preparation, structural and linear optical properties of Zn doped CdS nanopowders

    NASA Astrophysics Data System (ADS)

    Sekhar, H.; Rakesh Kumar, Y.; Narayana Rao, D.

    2015-02-01

    A series of Zn doped cadmium sulfide (CdS:Zn) nanopowders were prepared by a simple co-precipitation method at room temperature by mixing the stoichiometric amount of reactants in a Milli Q water solvent. The composition of nanopowders was accurately adjusted by controlling the molar ratio of Cd, Zn acetate in the mixed reactants. Spectroscopic studies on as prepared nanopowders were investigated by using XRD, Raman, UV-Vis absorption, FE- SEM-EDAX and photoluminescence. Extremely broad reflections of XRD peaks of as prepared powders establish the nanometer scale dimensions and cubic structure. Doping with Zn in CdS does not lead to any structural phase transformation but introduces a decrease in the lattice constants. Two characteristics of LO phonon peaks were observed in pure and Zn doped CdS samples. Raman peaks of Zn doped CdS nanopowders shifts slightly towards higher energy side compared to the pure CdS nanopowders. Exciton-phonon confinement factor (S) varies in between 0.3-0.4. At lower wavelength excitation we observed a broad emission peak maximum centered at 404 nm is attributed to localized band edge emission.

  6. Predicting As, Cd and Pb uptake by rice and vegetables using field data from China.

    PubMed

    Zhang, Hongzhen; Luo, Yongming; Song, Jing; Zhang, Haibo; Xia, Jiaqi; Zhao, Qiguo

    2011-01-01

    Plant uptake factor (PUF), single-variable regression of natural log-transformed concentrations in rice grain/vegetables versus natural log-transformed concentrations in soil and multiple-variable regression with soil concentrations and pH, was derived, validated and compared based on the paired crop and soil data collected from studies regarding As, Cd and Pb contaminated croplands in China. Results showed that the median value of PUF did not present deterministic prediction. But after natural logarithm transformation, the PUF followed Gaussian distribution which could be useful in risk assessment. The single-variable regression models were significant for As, Cd and Pb uptake both by rice and vegetables; however, the standard errors of all the regressions were comparatively large. Soil pH as a variable was generally significant but it only contributed positively to model fit for Cd uptake. After model comparison and selection, the upper 95% prediction limits of the multiple regression model for Cd uptake by rice was recommended to calculate screening value of Cd for paddy soil based on the limit for Cd concentration in rice grain. PMID:21476343

  7. Spectral analysis of Cu(2+): B(2)O(3)--ZnO--PbO glasses.

    PubMed

    Lakshminarayana, G; Buddhudu, S

    2005-11-01

    A new series of heavy metal oxide (PbO) based zinc borate glasses in the chemical composition of (95-x)B(2)O(3)-5ZnO-xPbO (x=10, 15, 20, 25, 30, 35, 40, 45 and 50 mol%) have been prepared to verify their UV filtering performance. Both direct and indirect optical band gaps (E(opt)) have been evaluated for these glasses. For a reference glass of 45B(2)O(3)-5ZnO-50PbO, refractive indices at different wavelengths are measured and found the results satisfactorily correlated with the theoretical data upon the computation of Cauchy's constants of A=1.766029949, B=159531.024 nm(2) and C=-1.078 x 10(10) nm(4). Measurements concerning X-ray diffraction (XRD), FT-IR, differential scanning colorimeter (DSC) profiles have been carried out for this glass. The FT-IR profile has revealed that the glass has both BO(3) and BO(4) units. From DSC thermogram, glass transition temperature (T(g)), crystallization temperature (T(c)) and melting temperature (T(m)) have been located and from them, other related parameters of the glass have also been calculated. Visible absorption spectra of 45B(2)O(3)-5ZnO-(50-x)PbO-xCuO (x=0. 1, 0.2, 0.5 and 1.0 mol%) have revealed two absorption bands at around 400 nm ((2)B(1g)-->(2)E(g)) and 780 nm ((2)B(1g)-->(2)B(2g)) of Cu(2+) ions, respectively. Emission bands at 422 and 512 nm are found for the 1 mol % CuO doped glass with excitations at 306 and 332 nm.

  8. Subcellular compartmentalization of Cd and Zn in two bivalves. II. Significance of trophically available metal (TAM)

    USGS Publications Warehouse

    Wallace, W.G.; Luoma, S.N.

    2003-01-01

    This paper examines how the subcellular partitioning of Cd and Zn in the bivalves Macoma balthica and Potamocorbula amurensis may affect the trophic transfer of metal to predators. Results show that the partitioning of metals to organelles, 'enzymes' and metallothioneins (MT) comprise a subcellular compartment containing trophically available metal (TAM; i.e. metal trophically available to predators), and that because this partitioning varies with species, animal size and metal, TAM is similarly influenced. Clams from San Francisco Bay, California, were exposed for 14 d to 3.5 ??g 1-1 Cd and 20.5 ??g 1-1 Zn, including 109Cd and 65Zn as radiotracers, and were used in feeding experiments with grass shrimp Palaemon macrodatylus, or used to investigate the subcellular partitioning of metal. Grass shrimp fed Cd-contaminated P. amurensis absorbed ???60% of ingested Cd, which was in accordance with the partitioning of Cd to the bivalve's TAM compartment (i.e. Cd associated with organelles, 'enzymes' and MT); a similar relationship was found in previous studies with grass shrimp fed Cd-contaminated oligochaetes. Thus, TAM may be used as a tool to predict the trophic transfer of at least Cd. Subcellular fractionation revealed that ???34% of both the Cd and Zn accumulated by M. balthica was associated with TAM, while partitioning to TAM in P. amurensis was metal-dependent (???60% for TAM-Cd%, ???73% for TAM-Zn%). The greater TAM-Cd% of P. amurensis than M. balthica is due to preferential binding of Cd to MT and 'enzymes', while enhanced TAM-Zn% of P. amurensis results from a greater binding of Zn to organelles. TAM for most species-metal combinations was size-dependent, decreasing with increased clam size. Based on field data, it is estimated that of the 2 bivalves, P. amurensis poses the greater threat of Cd exposure to predators because of higher tissue concentrations and greater partitioning as TAM; exposure of Zn to predators would be similar between these species.

  9. Formation of ZnTe:Cu/Ti Contacts at High Temperature for CdS/CdTe Devices: Preprint

    SciTech Connect

    Gessert, T. A.; Asher, S.; Johnston, S.; Duda, A.; Young, M. R.; Moriarty, T.

    2006-05-01

    We study the performance of CdS/CdTe thin-film devices contacted with ZnTe:Cu/Ti of various thickness at a higher-than-optimum temperature of {approx}360 C. At this temperature, optimum device performance requires the same thickness of ZnTe:Cu as for similar contacts formed at a lower temperature of 320 C. C-V analysis indicates that a ZnTe:Cu layer thickness of {approx}< 0.5 mu m does not yield the degree of CdTe net acceptor concentration necessary to reduce space charge width to its optimum value for n-p device operation. The thickest ZnTe:Cu layer investigated (1 mu m) yields the highest CdTe net acceptor concentration, lowest value of Jo, and highest Voc. However, performance is limited for this device by poor fill factor. We suggest poor fill factor is due to Cu-related acceptors compensating donors in CdS.

  10. Photoluminescence of localized excitons in ZnCdO thin films grown by molecular beam epitaxy

    NASA Astrophysics Data System (ADS)

    Wu, T. Y.; Huang, Y. S.; Hu, S. Y.; Lee, Y. C.; Tiong, K. K.; Chang, C. C.; Shen, J. L.; Chou, W. C.

    2016-07-01

    We have investigated the luminescence characteristics of Zn1-xCdxO thin films with different Cd contents grown by molecular beam epitaxy system. The temperature-dependent photoluminescence (PL) and excitation power-dependent PL spectra were measured to clarify the luminescence mechanisms of the Zn1-xCdxO thin films. The peak energy of the Zn1-xCdxO thin films with increasing the Cd concentration is observed as redshift and can be fitted by the quadratic function of alloy content. The broadened full-width at half-maximum (FWHM) estimated from the 15 K PL spectra as a function of Cd content shows a larger deviation between the experimental values and theoretical curve, which indicates that experimental FWHM values are affected not only by alloy compositional disorder but also by localized excitons occupying states in the tail of the density of states. The Urbach energy determined from an analysis of the lineshape of the low-energy side of the PL spectrum and the degree of localization effect estimated from the temperature-induced S-shaped PL peak position described an increasing mean exciton-localization effects in ZnCdO films with increasing the Cd content. In addition, the PL intensity and peak position as a function of excitation power are carried out to clarify the types of radiative recombination and the effects of localized exciton in the ZnCdO films with different Cd contents.

  11. Cumulative rate and distribution of Cd and Pb in the organs of adult male Wistar rats during oral exposure.

    PubMed

    Winiarska-Mieczan, Anna

    2014-11-01

    The degree of accumulation of Cd and Pb in the brains, spleens, lungs, hearts, livers and kidneys of adult Wistar rats was compared both for separate (Cd or Pb) and combined (Cd+Pb) oral exposure. In addition, the metals were administered either with liquids or with solid feed. Rats were exposed to low doses of metals (7mg Cd and 50mg Pb/kg feed or L of distilled water) over 6 or 12 weeks. In total the organs of rats accumulated about 0.3-0.5% Cd and 0.4-0.6% Pb supplied with food or drink. The presented studies demonstrated that the distribution of Cd and Pb in the organs is affected by: the type of exposure (separate or combined), the source of metals (feed or drinks) and the duration of exposure. It was found that simultaneous exposure to low doses of Cd and Pb supplied with food is much more hazardous than exposure to such metals supplied with water.

  12. CdSe/Cd(x)Zn1-xS core/shell nanocrystals: core morphology and luminescent property.

    PubMed

    Yang, Ping; Yang, Jie; Cao, Yongqiang; Ma, Qian; Zhang, Aiyu; Wang, Jianrong; Shi, Ruixia; Zhu, Yuanna

    2012-06-01

    CdSe cores with rod (an aspect ratio of 1.8, d-5 nm) and spherical (an aspect ratio of 1, d-5 nm) morphologies were fabricated by two kinds of organic approaches through adjusting growth processes. Because of large difference of size and morphology, two kinds of cores revealed different absorption spectra. However, these cores exhibited almost same photoluminescence (PL) spectra with a red-emitting PL peak of around 625 nm. This is ascribed that they have a similar size in diameter. A graded Cd(x)Zn1-xS shell of larger band gap was grown around CdSe rods and spheres using oleic acid as a capping agent. Based on the growth kinetics of CdS and ZnS, interfacial segregation was created to preferentially deposit CdS near the core, providing relaxation of the strain at the core/shell interface. For spherical CdSe cores, the homogeneous deposition of the Cd(x)Zn1-xS shell created spherical core/shell nanocrystals (NCs) with a size of 7.1 nm in diameter. In the case of using CdSe cores with rod morphology, the anisotropic aggregation behaviors of CdS monomers on CdSe rods led to the size (approximately 10 nm in diameter) of spherical CdSe/Cd(x)Zn1-xS core/shell NCs with a small difference to the length of the CdSe rod (approximately 8.9 nm). The resulting spherical core/shell NCs created by the rod and spherical cores exhibited almost same PL peak wavelength (652 and 653 nm for using rod and spherical cores, respectively), high PL efficiency up to 50%, and narrow PL spectra (36 and 28 nm of full with at half maximum of PL spectra for the core/shell NCs with CdSe spheres and rods, respectively). These core/shell NCs provide an opportunity for the study of the evolution of PL properties as the shape of semiconductor NCs.

  13. Continuous biosorption of Pb/Cu and Pb/Cd in fixed-bed column using algae Gelidium and granulated agar extraction algal waste.

    PubMed

    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. PMID:18162305

  14. Ore geology and fluid inclusion geochemistry of the Tiemurt Pb-Zn-Cu deposit, Altay, Xinjiang, China: A case study of orogenic-type Pb-Zn systems

    NASA Astrophysics Data System (ADS)

    Zhang, Li; Zheng, Yi; Chen, YanJing

    2012-04-01

    The Tiemurt Pb-Zn-Cu deposit is hosted in a Devonian volcanic-sedimentary basin of the Altay orogenic belt, and is thus interpreted to have formed by sea-floor hydrothermal exhalation in previous studies. Our investigation discovered that the deposit is not stratiform or stratabound, but structure-controlled instead. The hydrothermal ore-forming process can be divided into the early, middle and late stage, represented by pyrite-quartz, polymetallic sulfide-quartz and carbonate-quartz veinlets, respectively. The early-stage veins and contained minerals are structurally deformed and brecciated, suggesting a compressional or transpressional tectonic regime. The middle-stage veinlets intrude and infill the fissures of the early-stage assemblages, and show no deformation, suggesting a tensional shear setting. The late-stage veinlets mostly infill open-space fissures that crosscut veins and replacements formed in the earlier stages. Four types of fluid inclusions (FIs), including aqueous (type W), carbonic-aqueous (type C), pure carbonic (type PC) and solid-bearing (type S), are identified at the Tiemurt deposit. The early-stage minerals contain the C- and W-type primary FIs that are totally homogenized at temperatures of 330-390 °C with low salinities of 0.8-11.9 wt.% NaCl eqv.; whilst the late-stage quartz or calcite contains only the W-type FIs with homogenization temperatures of 118-205 °C, and salinities of 1.4-3.4 wt.% NaCl eqv. This indicates that the ore fluid system evolved from CO2-rich, probably metamorphic to CO2-poor, meteoric fluids; and that a significant CO2-escape must have occurred. All the four types of FIs can be only observed in the middle-stage minerals, and even in a microscopic domain of a crystal, representing an association trapped from a boiling fluid system. These FIs homogenize at temperatures ranging from 270 to 330 °C, with two salinity clusters of 1.9-14.5 and 37.4-42.4 wt.% NaCl eqv., respectively. This implies that metal precipitation

  15. Enhanced lateral photovoltaic effect observed in CdSe quantum dots embedded structure of Zn/CdSe/Si.

    PubMed

    Lan, Tian; Liu, Shuai; Wang, Hui

    2011-01-01

    The quantum dots (QDs) system has been intensively studied for decades owing to its huge potential for applications. In this Letter, we report a lateral photovoltaic effect (LPE) with a large sensitivity observed in CdSe QDs embedded structure of Zn/CdSe/Si. This result not only enriches applications of the QDs system but also opens a new window to study the carrier dynamics of the QDs system.

  16. Formation of ZnTe:Cu/Ti Contacts at High Temperature for CdS/CdTe Devices (Presentation)

    SciTech Connect

    Gessert, T. A.; Asher, S.; Johnston, S.; Duda, A.; Young, M. R.; Moriarty, T.

    2006-05-01

    The conclusions of this report are that Cu diffusion from a ZnTe:Cu contact causes good and bad things. The good (Cu in CdS < low 10{sup 18} cm{sup -3})--increase in CdTe N{sub A}-N{sub D} that leads to V{sub oc} and FF improvement. The bad (Cu in CdS > low 10{sup 18} cm{sup -3})--(1) possibly decreased of shunt resistance (?); (2) depletion width in CdTe can become too narrow for optimum current collection at J{sub MPP}; (3) donor reduction in CdS (significant FF loss in LIV); and (4) excessive Cu diffusion into CdS readily observed by red-light bias QE.

  17. Molecular beam epitaxial re-growth of CdTe, CdTe/CdMgTe and CdTe/CdZnTe double heterostructures on CdTe/InSb(1 0 0) substrates with As cap

    NASA Astrophysics Data System (ADS)

    Seyedmohammadi, Shahram; DiNezza, Michael J.; Liu, Shi; King, Paul; LeBlanc, Elizabeth G.; Zhao, Xin-Hao; Campbell, Calli; Myers, Thomas H.; Zhang, Yong-Hong; Malik, Roger J.

    2015-09-01

    Molecular beam epitaxial growth on CdTe substrates is challenging since the CdTe film crystalline and optical quality is limited by residual defects including threading dislocations and stacking faults. This remains an obstacle in spite of exhausting variables including pre-growth substrate preparation as well as epitaxial growth conditions including thermal oxide desorption, growth temperature, and II/VI flux ratios. We propose a new technique to re-grow structures with low defect densities and high optical and structural quality on InSb substrates. The "CdTe virtual wafer" is made by growing a thin CdTe film on an InSb(1 0 0) substrate which is then covered with a thin As cap layer to prevent oxidation of the CdTe surface. The As cap can be removed by thermal desorption at about 300 C leaving a clean CdTe surface for subsequent epitaxial growth. This method eliminates the need for chemical etching of CdTe substrates which has been found to lead to an atomically rough surface with residual Carbon and Oxygen contamination. XRD and SEM characterization show a smooth transition from the buffer CdTe to re-grown CdTe layer with identical crystalline quality as for virtual wafer. Steady-state PL and time-resolved PL from CdTe/CdMgTe double heterostructures show substantial improvement in luminescence intensity and carrier lifetime comparable to values for identical samples grown without exposure to atmosphere. We will also report on CdTe/CdZnTe double heterostructures grown on virtual wafers compared to identical structures on conventional CdTe(2 1 1)B substrates.

  18. Fluids in distal Zn-Pb-Ag skarns: Evidence from El Mochito, Honduras

    NASA Astrophysics Data System (ADS)

    Samson, I. M.; Williams-Jones, A. E.; Ault, K.; Gagnon, J. E.; Fryer, B. J.

    2009-05-01

    Zn-Pb-Ag mantos, chimneys, and skarns represent a spectrum of carbonate-hosted sulfide mineral deposits that have been collectively termed carbonate replacement deposits. Most such deposits cannot be related to plutons and, particularly for distal skarns, the role of magmatic versus other fluids (basinal brines and meteoric waters) has been uncertain. The El Mochito Zn-Pb-Ag deposit, Honduras, is an example of a large distal skarn, and comprises mantos and chimneys hosted mainly by limestones of the Early Cretaceous Tepemechin Formation. Previous isotopic studies indicate a magmatic source for the S and Pb and involvement of both magmatic and meteoric fluids in ore formation. The ore is hosted by garnet, magnetite, and pyroxene skarns, which developed sequentially from grandite- to andradite- to magnetite- and hedenbergite- rich skarns. Sphalerite and argentiferous galena occur interstitially to, or replace, the skarn minerals, with Fe- poor sphalerite (S1) principally associated with garnet skarn and Fe-rich (S2) sphalerite associated with pyroxene. Data from primary fluid inclusions show that the salinity of the mineralizing fluids decreased from ˜10-18 wt. % during the formation of garnet skarn and S1 sphalerite to ˜2-13 wt. % during pyroxene skarn formation and S2 sphalerite precipitation. Early, high-salinity fluids (˜33 wt. %) are represented by rare halite-saturated inclusions in garnet. Temperature increased from ˜ 365°C to ˜ 365°C from garnet/S1 sphalerite to pyroxene/S2 sphalerite, assuming a pressure of 500 bars. GC analyses indicate that the total concentrations of COv(2), CH4, and N2 were < 1 mole %. LA-ICPMS analyses were conducted mainly on inclusions in grandite and S1 sphalerite. The principal dissolved elements in the inclusions are Ca and Na, followed by K and Mn. The ore metals, Zn, Pb, and Ag, are present in high concentrations, with median values of 6000, 900, and 50 ppm, respectively. Element concentrations in fluid inclusions hosted

  19. Varying effect of biochar on Cd, Pb and As mobility in a multi-metal contaminated paddy soil.

    PubMed

    Yin, Daixia; Wang, Xin; Chen, Can; Peng, Bo; Tan, Changyin; Li, Hailong

    2016-06-01

    Cd, Pb and As stand as the most prominent contaminants prevailing in Chinese soils. In the present study, biochars derived from water hyacinth (BCW) and rice straw (BCR) were investigated regarding their applicability and durability in soil Cd, Pb, and As immobilization under acid precipitation. Total Cd, Pb, and As in both BCs were below the maximum allowed threshold according to biochar toxicity standard recommended by International Biochar Initiative. To evaluate BCs effect on Cd, Pb, As bioavailability and mobility, CaCl2, KH2PO4 and SPLP extractions were firstly carried out. In neutral extraction with CaCl2 and KH2PO4, significantly reduced Cd/Pb concentrations in CaCl2 extract along with elevated KH2PO4-extractable As were recorded with either BC at 2% or 5%. In SPLP with simulated acid rainwater as extractant, comparable Cd, Pb and As levels were determined in SPLP extract with 2% BCW, while slight to significant increase in SPLP-Cd, Pb or As was recorded with other treatments. Longer-term leaching column test further confirmed the high durability of 2% BCW in Cd immobilization under continuous acid exposure. In parallel, little increase in As concentrations in eluate was determined with 2% BCW compared to no-biochar control, indicating a lowered risk of As mobilization with acid input. However, remarkably higher Pb in leachate from both BCW-only control and 2% BCW-amended soils were noticed at the initial stage of acid leaching, indicating a higher acid-solubility of Pb minerals in BCW (most probably PbO) than in tested soil (PbO2, PbAs2O6). Taken together, BCW exhibited important potential for soil Cd sequestration with little effect on As mobilization under acid precipitation. But it may simultaneously load highly acid-soluble Pb minerals into soils, resulting in elevated Pb mobility upon acid exposure. Therefore, more stringent threshold for Pb content in biochar need to be put forward to secure biochar application in soils subject to anthropogenic

  20. Varying effect of biochar on Cd, Pb and As mobility in a multi-metal contaminated paddy soil.

    PubMed

    Yin, Daixia; Wang, Xin; Chen, Can; Peng, Bo; Tan, Changyin; Li, Hailong

    2016-06-01

    Cd, Pb and As stand as the most prominent contaminants prevailing in Chinese soils. In the present study, biochars derived from water hyacinth (BCW) and rice straw (BCR) were investigated regarding their applicability and durability in soil Cd, Pb, and As immobilization under acid precipitation. Total Cd, Pb, and As in both BCs were below the maximum allowed threshold according to biochar toxicity standard recommended by International Biochar Initiative. To evaluate BCs effect on Cd, Pb, As bioavailability and mobility, CaCl2, KH2PO4 and SPLP extractions were firstly carried out. In neutral extraction with CaCl2 and KH2PO4, significantly reduced Cd/Pb concentrations in CaCl2 extract along with elevated KH2PO4-extractable As were recorded with either BC at 2% or 5%. In SPLP with simulated acid rainwater as extractant, comparable Cd, Pb and As levels were determined in SPLP extract with 2% BCW, while slight to significant increase in SPLP-Cd, Pb or As was recorded with other treatments. Longer-term leaching column test further confirmed the high durability of 2% BCW in Cd immobilization under continuous acid exposure. In parallel, little increase in As concentrations in eluate was determined with 2% BCW compared to no-biochar control, indicating a lowered risk of As mobilization with acid input. However, remarkably higher Pb in leachate from both BCW-only control and 2% BCW-amended soils were noticed at the initial stage of acid leaching, indicating a higher acid-solubility of Pb minerals in BCW (most probably PbO) than in tested soil (PbO2, PbAs2O6). Taken together, BCW exhibited important potential for soil Cd sequestration with little effect on As mobilization under acid precipitation. But it may simultaneously load highly acid-soluble Pb minerals into soils, resulting in elevated Pb mobility upon acid exposure. Therefore, more stringent threshold for Pb content in biochar need to be put forward to secure biochar application in soils subject to anthropogenic

  1. Preliminary Performance of CdZnTe Imaging Detector Prototypes

    NASA Technical Reports Server (NTRS)

    Ramsey, B.; Sharma, D. P.; Meisner, J.; Gostilo, V.; Ivanov, V.; Loupilov, A.; Sokolov, A.; Sipila, H.

    1999-01-01

    The promise of good energy and spatial resolution coupled with high efficiency and near-room-temperature operation has fuelled a large International effort to develop Cadmium-Zinc-Telluride (CdZnTe) for the hard-x-ray region. We present here preliminary results from our development of small-pixel imaging arrays fabricated on 5x5x1-mm and 5x5x2-mm spectroscopy and discriminator-grade material. Each array has 16 (4x4) 0.65-mm gold readout pads on a 0.75-mm pitch, with each pad connected to a discrete preamplifier via a pulse-welded gold wire. Each array is mounted on a 3-stage Peltier cooler and housed in an ion-pump-evacuated housing which also contains a hybrid micro-assembly for the 16 channels of electronics. We have investigated the energy resolution and approximate photopeak efficiency for each pixel at several energies and have used an ultra-fine beam x-ray generator to probe the performance at the pixel boundaries. Both arrays gave similar results, and at an optimum temperature of -20 C we achieved between 2 and 3% FWHM energy resolution at 60 keV and around 15% at 5.9 keV. We found that all the charge was contained within 1 pixel until very close to the pixels edge, where it would start to be shared with its neighbor. Even between pixels, all the charge would be appropriately shared with no apparently loss of efficiency or resolution. Full details of these measurements will be presented, together with their implications for future imaging-spectroscopy applications.

  2. Dual emission in asymmetric "giant" PbS/CdS/CdS core/shell/shell quantum dots.

    PubMed

    Zhao, Haiguang; Sirigu, Gianluca; Parisini, Andrea; Camellini, Andrea; Nicotra, Giuseppe; Rosei, Federico; Morandi, Vittorio; Zavelani-Rossi, Margherita; Vomiero, Alberto

    2016-02-21

    Semiconducting nanocrystals optically active in the infrared region of the electromagnetic spectrum enable exciting avenues in fundamental research and novel applications compatible with the infrared transparency windows of biosystems such as chemical and biological optical sensing, including nanoscale thermometry. In this context, quantum dots (QDs) with double color emission may represent ultra-accurate and self-calibrating nanosystems. We present the synthesis of giant core/shell/shell asymmetric QDs having a PbS/CdS zinc blende (Zb)/CdS wurtzite (Wz) structure with double color emission close to the near-infrared (NIR) region. We show that the double emission depends on the excitation condition and analyze the electron-hole distribution responsible for the independent and simultaneous radiative exciton recombination in the PbS core and in the CdS Wz shell, respectively. These results highlight the importance of the driving force leading to preferential crystal growth in asymmetric QDs, and provide a pathway for the rational control of the synthesis of double color emitting giant QDs, leading to the effective exploitation of visible/NIR transparency windows. PMID:26837955

  3. Impaired leaf CO2 diffusion mediates Cd-induced inhibition of photosynthesis in the Zn/Cd hyperaccumulator Picris divaricata.

    PubMed

    Tang, Lu; Ying, Rong-Rong; Jiang, Dan; Zeng, Xiao-Wen; Morel, Jean-Louis; Tang, Ye-Tao; Qiu, Rong-Liang

    2013-12-01

    Mechanisms of cadmium (Cd)-induced inhibition of photosynthesis in the Zn/Cd hyperaccumulator Picris divaricata were investigated using photosynthesis limitation analysis. P. divaricata seedlings were grown in nutrient solution containing 0, 5, 10, 25, 50, or 75 μM Cd for 2 weeks. Total limitations to photosynthesis (TL) increased from 0% at 5 μM Cd to 68.8% at 75 μM Cd. CO2 diffusional limitation (DL) made the largest contribution to TL, accounting for 93-98% of TL in the three highest Cd treatments, compared to just 2-7% of TL attributable to biochemical limitation (BL). Microscopic imaging revealed significantly decreased stomatal density and mesophyll thickness in the three highest Cd treatments. Chlorophyll fluorescence parameters related to photosynthetic biochemistry (Fv/Fm, NPQ, ΦPSII, and qP) were not significantly decreased by increased Cd supply. Our results suggest that increased DL in leaves is the main cause of Cd-induced inhibition of photosynthesis in P. divaricata, possibly due to suppressed function of mesophyll and stomata. Analysis of chlorophyll fluorescence showed that Cd supply had little effect on photochemistry parameters, suggesting that the PSII reaction centers are not a main target of Cd inhibition of photosynthesis in P. divaricata. PMID:24077231

  4. Impaired leaf CO2 diffusion mediates Cd-induced inhibition of photosynthesis in the Zn/Cd hyperaccumulator Picris divaricata.

    PubMed

    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.

  5. Locating Pb2+ and Zn2+ in Zinc Finger-Like Peptides Using Mass Spectrometry

    NASA Astrophysics Data System (ADS)

    Banu, Laura; Blagojevic, Voislav; Bohme, Diethard K.

    2013-10-01

    The binding preferences of Pb2+and Zn2+ in doubly charged complexes with zinc finger-like 12-residue peptides (Pep), [Mn(Pep-2(n-1)H)]2+ have been explored using tandem mass spectrometry. The peptides were synthesized strategically by blocking the N-terminus with an acetyl group and with four cysteine and/or histidine residues in positions 2, 5, 8, and 11, arranged in different motifs: CCHH, CHCH, and CCCC. The MS2 spectra of the Pb2+ and Zn2+ complexes show multiple losses of water and a single methane loss and these provide a sensitive method for locating the metal dication and so elucidating its coordination. The elimination of a methane molecule indicated the position of the metal at the Cys2 residue. Whereas lead was observed to preferentially bind to cysteine residues, zinc was found to primarily bind to histidine residues and secondarily to cysteine residues. Preferential binding of lead to cysteine is preserved in the complexes with more than one Pb2+. Key to the mechanism of the loss of water and methane is the metal dication withdrawing electrons from the proximal amidic nitrogen. This acidic nitrogen loses its hydrogen to an amidic oxygen situated four atoms away leading to formation of a five-member ring and the elimination of water.

  6. Elucidation of Two Giants: Challenges to Thick-shell Synthesis in CdSe/ZnSe and ZnSe/CdS Core/Shell Quantum Dots

    SciTech Connect

    Acharya, Krishna P.; Nguyen, Hue M.; Paulite, Melissa; Piryatinski, Andrei; Zhang, Jun; Casson, Joanna Lee; Xu, Hongwu; Htoon, Han; Hollingsworth, Jennifer Ann

    2015-03-06

    Core/thick-shell "giant" quantum dots (gQDs) possessing type II electronic structures exhibit suppressed blinking and diminished nonradiative Auger recombination. Here we investigate CdSe/ZnSe and ZnSe/CdS as potential new gQDs. We show theoretically and experimentally that both can exhibit partial or complete spatial separation of an excited-state electron–hole pair (i.e., type II behavior). However, we reveal that thick-shell growth is challenged by competing processes: alloying and cation exchange. We demonstrate that these can be largely avoided by choice of shelling conditions (e.g., time, temperature, and QD core identity). The resulting CdSe/ZnSe gQDs exhibit unusual single-QD properties, principally emitting from dim gray states but having high two-exciton (biexciton) emission efficiencies, whereas ZnSe/CdS gQDs show characteristic gQD blinking suppression, though only if shelling is accompanied by partial cation exchange.

  7. Elucidation of Two Giants: Challenges to Thick-shell Synthesis in CdSe/ZnSe and ZnSe/CdS Core/Shell Quantum Dots

    DOE PAGES

    Acharya, Krishna P.; Nguyen, Hue M.; Paulite, Melissa; Piryatinski, Andrei; Zhang, Jun; Casson, Joanna Lee; Xu, Hongwu; Htoon, Han; Hollingsworth, Jennifer Ann

    2015-03-06

    Core/thick-shell "giant" quantum dots (gQDs) possessing type II electronic structures exhibit suppressed blinking and diminished nonradiative Auger recombination. Here we investigate CdSe/ZnSe and ZnSe/CdS as potential new gQDs. We show theoretically and experimentally that both can exhibit partial or complete spatial separation of an excited-state electron–hole pair (i.e., type II behavior). However, we reveal that thick-shell growth is challenged by competing processes: alloying and cation exchange. We demonstrate that these can be largely avoided by choice of shelling conditions (e.g., time, temperature, and QD core identity). The resulting CdSe/ZnSe gQDs exhibit unusual single-QD properties, principally emitting from dim gray statesmore » but having high two-exciton (biexciton) emission efficiencies, whereas ZnSe/CdS gQDs show characteristic gQD blinking suppression, though only if shelling is accompanied by partial cation exchange.« less

  8. Cd{sup 2+} versus Zn{sup 2+} uptake by the ZIP8 HCO{sub 3}{sup -}-dependent symporter: Kinetics, electrogenicity and trafficking

    SciTech Connect

    Liu Zhiwei; Li Hong; Soleimani, Manoocher; Girijashanker, Kuppuswami; Reed, Jodie M.; He Lei; Dalton, Timothy P.; Nebert, Daniel W.

    2008-01-25

    The mouse Slc39a8 gene encodes the ZIP8 transporter, which has been shown to be a divalent cation/HCO{sub 3}{sup -} symporter. Using ZIP8 cRNA-injected Xenopus oocyte cultures, we show herein that: [a] ZIP8-mediated cadmium (Cd{sup 2+}) and zinc (Zn{sup 2+}) uptake have V{sub max} values of 1.8 {+-} 0.08 and 1.0 {+-} 0.08 pmol/oocyte/h, and K{sub m} values of 0.48 {+-} 0.08 and 0.26 {+-} 0.09 {mu}M, respectively; [b] ZIP8-mediated Cd{sup 2+} uptake is most inhibited by Zn{sup 2+}, second-best inhibited by Cu{sup 2+}, Pb{sup 2+} and Hg{sup 2+}, and not inhibited by Mn{sup 2+} or Fe{sup 2+}; and [c] electrogenicity studies demonstrate an influx of two HCO{sub 3}{sup -} anions per one Cd{sup 2+} (or one Zn{sup 2+}) cation, i.e. electroneutral complexes. Using Madin-Darby canine kidney (MDCK) polarized epithelial cells retrovirally infected with ZIP8 cDNA and tagged with hemagglutinin at the C-terminus, we show that-similar to ZIP4-the ZIP8 eight-transmembrane protein is largely internalized during Zn{sup 2+} homeostasis, but moves predominantly to the cell surface membrane (trafficking) under conditions of Zn{sup 2+} depletion.

  9. Phytoextraction of Cd and Zn as single or mixed pollutants from soil by rape (Brassica napus).

    PubMed

    Cojocaru, Paula; Gusiatin, Zygmunt Mariusz; Cretescu, Igor

    2016-06-01

    This paper analyses the capacity of the rape (Brassica napus) to extract Cd and Zn from the soil and the effect of these metals on the morphometric parameters of the plant (length, weight, surface area, fractal dimension of leaves). Rape plants were mostly affected by the combined toxicity of the Cd and Zn mixture that caused a significant reduction in the rate of seed germination, the plant biomass quantity and the fractal dimension. In the case of Cd soil pollution, the bioaccumulation factor (BAF), bioaccumulation coefficient (BAC) as well as the heavy metal root-to-stalk translocation factor (TF) were determined. The results showed that B. napus had a great potential as a cadmium hyperaccumulator but not as an accumulator of Zn or Cd + Zn mixture. The efficiency of phytoextraction rape was 0.8-1.22 % for a soil heavily polluted with cadmium. PMID:26884243

  10. CdS/PbSe heterojunction for high temperature mid-infrared photovoltaic detector applications

    SciTech Connect

    Weng, Binbin E-mail: shi@ou.edu; Qiu, Jijun; Zhao, Lihua; Chang, Caleb; Shi, Zhisheng E-mail: shi@ou.edu

    2014-03-24

    n-CdS/p-PbSe heterojunction is investigated. A thin CdS film is deposited by chemical bath deposition on top of epitaxial PbSe film by molecular beam epitaxy on Silicon. Current-voltage measurements demonstrate very good junction characteristics with rectifying ratio of ∼178 and ideality factor of 1.79 at 300 K. Detectors made with such structure exhibit mid-infrared spectral photoresponse at room temperature. The peak responsivity R{sub λ} and specific detectivity D{sup *} are 0.055 A/W and 5.482 × 10{sup 8} cm·Hz{sup 1/2}/W at λ = 4.7 μm under zero-bias photovoltaic mode. Temperature-dependent photoresponse measurements show abnormal intensity variation below ∼200 K. Possible reasons for this phenomenon are also discussed.

  11. Analysis of Cu Diffusion in ZnTe-Based Contacts for Thin-Film CdS/CdTe Solar Cells

    SciTech Connect

    Narayanswamy, C.; Gessert, T. A. and Asher, S. E.

    1998-10-27

    Ohmic contacts to thin-film CdS/CdTe photovoltaic devices have been formed using a two-layer contact interface of undoped ZnTe (ZnTe) and Cu-doped ZnTe (ZnTe:Cu), followed by Ni or Ti as an outer metallization. Secondary ion mass spectroscopy (SIMS) is used to study Cu diffusion within this back-contact structure, and also, to monitor Cu diffusion from the contact into the CdTe. When Ni metallization is used, the ZnTe:Cu layer becomes increasingly depleted of Cu, and Ni diffusion into the ZnTe:Cu increases as the contact deposition temperature increases from 100 C to 300 C. Cu depletion is not observed when Ni is replaced with Ti. Diffusion of Cu from the ZnTe:Cu layer into the ZnTe layer also increases with contact deposition temperature, and produces a buildup of Cu at the ZnTe/CdTe interface. High-mass resolution SIMS indicates that, although Cu levels in the CdTe remain low, Cu diffusion from the contact proceeds into the CdTe layer and toward the CdTe/CdS junction region.

  12. Bioavailability of Cd, Cr, and Zn to bivalves in south San Francisco Bay

    SciTech Connect

    Lee, B.G.; Luoma, S.N.; Geen, A. van

    1995-12-31

    The bioavailability of Cd, Cr, and Zn to benthic bivalves (Potamocorbular amurensis and Macoma balthica) is affected by the type of natural particles the animals ingest, and the concentration and speciation of dissolved metals. During a spring phytoplankton bloom in south San Francisco Bay dissolved Cd and Zn concentrations decreased to about half of pre-bloom concentrations. The concentrations of particulate Cd and Zn concentrations increased due to preferential uptake of these metals by phytoplankton. Assimilation of Cd was more efficient when clams ate pure phytoplankton (80% for M. balthica and 29% for P. amurensis) than when they were exposed to inorganic-dominated particles. M. balthica and P. amurensis assimilated 72% and 42% of Zn associated with the particles during the bloom. Assimilation of Cr was low (<6%) and particle type had little effect on its availability. Accumulation of Cd via the dissolved route was low in high salinity waters (15 ppt). Metal bioaccumulation in the bivalves was modeled using the experimentally determined physiological parameters. The results were compared to metal concentrations in clams from the Bay. The model suggested that the clams accumulated Cd and Zn at higher rates during the phytoplankton bloom, although dissolved metal concentrations in the water column were reduced.

  13. Relationship between the cathodoluminescence emission and resistivity in In doped CdZnTe crystals

    SciTech Connect

    Rodriguez-Fernandez, J.; Carcelen, V.; Dieguez, E.; Hidalgo, P.; Piqueras, J.; Vijayan, N.; Sochinskii, N. V.; Perez, J. M.

    2009-08-15

    Cadmium zinc telluride, CdZnTe, bulk single crystals doped with 10{sup 19} at./cm{sup 3} of indium in the initial melt were grown by vertical Bridgman technique. The samples were investigated by energy dispersive spectroscopy, cathodoluminiscence (CL), and current-voltage behavior at room temperature. The results shows that Cd and Te vacancy concentration depend on the indium and zinc concentrations. CL measurements indicate a relationship between radiative centers associated to Cd and Te vacancies and resistivity values.

  14. Chemical immobilization of Pb, Cu, and Cd by phosphate materials and calcium carbonate in contaminated soils.

    PubMed

    Huang, Guoyong; Su, Xiaojuan; Rizwan, Muhammad Shahid; Zhu, Yifei; Hu, Hongqing

    2016-08-01

    Soil contamination with toxic metals has increasingly become a global concern over the past few decades. Phosphate and carbonate compounds are good passivation materials for Pb immobilization, while the effect of phosphate and carbonate on the immobilization of multiple heavy metals (Pb, Cu, and Cd) in contaminated soils was seldom investigated. In this study, bone meal (BM), phosphate rock (PR), oxalic acid-activated phosphate rock (APR), super phosphate (SP), and calcium carbonate (CC) were added to the contaminated soils to evaluate the effect of phosphate materials and calcium carbonate on the immobilization of Pb, Cu, and Cd. The results showed that the pH of the treated soils increased 1.3-2.7, except SP which decreased 0.5 at most. Compared to the control treatment, all phosphates and calcium carbonate added to the polluted soils increased the fraction of residual metals, and the application of APR, PR, BM, and CC significantly reduced exchangeable and carbonate-bound fraction metals. PR and APR were the most effective for the immobilization of Pb, Cu, and Cd in the soils among these materials. Moreover, the concentrations of all metals in the toxicity characteristic leaching procedure (TCLP) leachate decreased with increasing amounts of amendments, and the concentrations of Pb in the TCLP leachate for soils treated with PR and APR were below the nonhazardous regulatory limit of 5 mg L(-1) (US Environmental Protection Agency). Based on our results, phosphate rock and oxalic acid-activated phosphate rock are effective in the immobilization of multiple metals by reducing their mobility in the co-contaminated soils. PMID:27197655

  15. Chemical immobilization of Pb, Cu, and Cd by phosphate materials and calcium carbonate in contaminated soils.

    PubMed

    Huang, Guoyong; Su, Xiaojuan; Rizwan, Muhammad Shahid; Zhu, Yifei; Hu, Hongqing

    2016-08-01

    Soil contamination with toxic metals has increasingly become a global concern over the past few decades. Phosphate and carbonate compounds are good passivation materials for Pb immobilization, while the effect of phosphate and carbonate on the immobilization of multiple heavy metals (Pb, Cu, and Cd) in contaminated soils was seldom investigated. In this study, bone meal (BM), phosphate rock (PR), oxalic acid-activated phosphate rock (APR), super phosphate (SP), and calcium carbonate (CC) were added to the contaminated soils to evaluate the effect of phosphate materials and calcium carbonate on the immobilization of Pb, Cu, and Cd. The results showed that the pH of the treated soils increased 1.3-2.7, except SP which decreased 0.5 at most. Compared to the control treatment, all phosphates and calcium carbonate added to the polluted soils increased the fraction of residual metals, and the application of APR, PR, BM, and CC significantly reduced exchangeable and carbonate-bound fraction metals. PR and APR were the most effective for the immobilization of Pb, Cu, and Cd in the soils among these materials. Moreover, the concentrations of all metals in the toxicity characteristic leaching procedure (TCLP) leachate decreased with increasing amounts of amendments, and the concentrations of Pb in the TCLP leachate for soils treated with PR and APR were below the nonhazardous regulatory limit of 5 mg L(-1) (US Environmental Protection Agency). Based on our results, phosphate rock and oxalic acid-activated phosphate rock are effective in the immobilization of multiple metals by reducing their mobility in the co-contaminated soils.

  16. Field evaluation of the effectiveness of three industrial by-products as organic amendments for phytostabilization of a Pb/Zn mine tailings.

    PubMed

    Yang, Shengxiang; Cao, Jianbing; Li, Fengmei; Peng, Xizhu; Peng, Qingjing; Yang, Zhihui; Chai, Liyuan

    2016-01-01

    Although the potential of industrial by-products as organic amendments for phytostabilization has long been recognized, most of the previous studies addressing this issue have been laboratory-based. In this study, a field trial was conducted to evaluate the effectiveness of three industrial by-products [sweet sorghum vinasse (SSV), medicinal herb residues (MHR) and spent mushroom compost (SMC)] as organic amendments for phytostabilization of abandoned Pb/Zn mine tailings. Our results showed the following: (i) when compared to the control tailings, the mean concentrations of diethylene-triamine-pentaacetic acid (DTPA)-extractable Cd, Cu, Pb and Zn in SSV, MHR and SMC treatments decreased by 20.8-28.0%, 41.6-49.1%, 17.7-22.7% and 9.5-14.7%, respectively; (ii) the mean values of organic C, ammonium-N and available P in SSV, MHR and SMC treatments increased by 1.7-2.8, 10.8-14.9 and 3.9-5.1 times as compared with the mine tailings; and (iii) the addition of SSV, MHR and SMC significantly enhanced soil respiration and microbial biomass being 1.5-1.8 and 1.3-1.6 fold higher than those in the control tailings. There were no significant differences in soil biochemical properties among the plots amended with these by-products, suggesting that they were almost equally effective in improving the biochemical conditions of the tailings. In addition, the application of these amendments promoted seed germination, seedling growth, and consequently increased the vegetation cover and its biomass. Moreover, concentrations of Cd, Cu, Pb and Zn in above-ground parts of the plants were below the toxicity limit levels for animals. The results obtained in this field study confirmed that the three organic-rich industrial by-products could be used as amendments for phytostabilization of some types of mine tailings. PMID:26611119

  17. Bioaccessibility of Cd and Pb in tailings from a zinc smelting in Brazil: implications for human health.

    PubMed

    Ono, F B; Penido, E S; Tappero, R; Sparks, D; Guilherme, L R G

    2016-10-01

    Soils and wastes enriched with heavy metals may present ecological and human health risks. A considerable number of mining areas exist in Brazil, where high levels of metals have been found. However, studies of bioaccessibility of metals in soils/tailings from these areas are scarce, despite their potential informational contribution concerning exposure risks of residents near these areas. This study evaluated tailings collected from four sites of a zinc smelting area located in Brazil with aims to: (1) evaluate the presence of metals of potential concern; (2) investigate Cd and Pb bioaccessibility; and (3) determine the desorption kinetics of Cd and Pb. High concentrations of total Cd and Pb (up to 1743 mg Cd kg(-1) and 8675 mg Pb kg(-1)) and great variability were found in the tailings, indicating the importance of adequate planning for their final disposal, in order to avoid contamination in the surrounding environment. Cadmium and Pb bioaccessibility percentages in the intestinal phase were less than 47 and 4 %, respectively, which represents significant fractions not available for absorption in the intestinal tract. However, this material has to be monitored since its bioaccessibility may increase with eventual physicochemical changes, releasing Cd and Pb. Desorption kinetics experiments revealed that Pb in the samples remained in less labile fractions, whereas Cd was found in more labile fractions, which is in accordance with the bioaccessibility results.

  18. Competitive adsorption of Pb2+ and Cd2+ on magnetic modified sugarcane bagasse prepared by two simple steps

    NASA Astrophysics Data System (ADS)

    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.

  19. Multiple site study of recent atmospheric metal (Pb, Zn and Cu) deposition in the NW Iberian Peninsula using peat cores.

    PubMed

    Olid, Carolina; Garcia-Orellana, Jordi; Martínez-Cortizas, Antonio; Masqué, Pere; Peiteado-Varela, Eva; Sanchez-Cabeza, Joan-Albert

    2010-10-15

    In order to estimate atmospheric metal deposition in Southern Europe since the beginning of the Industrial Period (~1850 AD), concentration profiles of Pb, Zn and Cu were determined in four (210)Pb-dated peat cores from ombrotrophic bogs in Serra do Xistral (Galicia, NW Iberian Peninsula). Maximum metal concentrations varied by a factor of 1.8 for Pb and Zn (70 to 128μgg(-1) and 128 to 231μgg(-1), respectively) and 3.5 for Cu (11 to 37μgg(-1)). The cumulative metal inventories of each core varied by a factor of 3 for all analysed metals (132 to 329μgcm(-2) for Pb, 198 to 625μgcm(-2) for Zn and 22 to 69μgcm(-2) for Cu), suggesting differences in net accumulation rates among peatlands. Although results suggest that mean deposition rates vary within the studied area, the enhanced (210)Pb accumulation and the interpretation of the inventory ratios ((210)Pb/Pb, Zn/Pb and Cu/Pb) in two bogs indicated that either a record perturbation or post-depositional redistribution effects must be considered. After correction, Pb, Zn and Cu profiles showed increasing concentrations and atmospheric fluxes since the mid-XX(th) century to maximum values in the second half of the XX(th) century. For Pb, maximum fluxes were observed in 1955-1962 and ranged from 16 to 22mgm(-2)yr(-1) (mean of 18±1mgm(-2)yr(-1)), two orders of magnitude higher than in the pre-industrial period. Peaks in Pb fluxes in Serra do Xistral before the period of maximum consumption of leaded petrol in Europe (1970s-1980s) suggest the dominance of local pollutant sources in the area (i.e. coal mining and burning). More recent peaks were observed for Zn and Cu, with fluxes ranging from 32 to 52mgm(-2)yr(-1) in 1989-1996, and from 4 to 9mgm(-2)yr(-1) in 1994-2001, respectively. Our results underline the importance of multi-core studies to assess both the integrity and reliability of peat records, and the degree of homogeneity in bog accumulation. We show the usefulness of using the excess (210)Pb inventory to

  20. Geological, rare earth elemental and isotopic constraints on the origin of the Banbanqiao Zn-Pb deposit, southwest China

    NASA Astrophysics Data System (ADS)

    Li, Bo; Zhou, Jia-Xi; Huang, Zhi-Long; Yan, Zai-Fei; Bao, Guang-Ping; Sun, Hai-Rui

    2015-11-01

    The newly discovered Banbanqiao Zn-Pb deposit in the southeastern part of the Sichuan-Yunnan-Guizhou (SYG) Pb-Zn metallogenic province is located on the western Yangtze Block, southwest China. Ore bodies of the Banbanqiao deposit are stratiform type, host in dolomitic limestone and dolostone of the Lower Carboniferous Dapu Formation and occur within the NNE-trending Banbanqiao anticline. More than 1.5 million tones (Mt) Zn-Pb ores at grades of 0.26-10.32 wt.% Pb and 0.81-28.8 wt.% Zn have been controlled until now. δ13CPDB and δ18OSMOW values of calcite separates range from -2.8‰ to -0.7‰ (average -1.1‰) and +14.1‰ to +17.0‰ (average +15.5‰), respectively. The δ13CPDB values are similar to those of marine carbonate rocks, but higher than those of mantle and significantly different from those of sedimentary organic matter. However, the δ18OSMOW values are among those of mantle, marine carbonate rocks and sedimentary organic matter. δ34SCDT values of sulfide separates range from +3.2‰ to +9.9‰ (average +6.5‰), unlike mantle-derived sulfur (0 ± 3‰), whilst lower than evaporites (+22‰ to +28‰) within host strata. 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb values of country shale and dolostone whole-rock samples are 18.47, 15.66 and 38.70, and 18.44-18.60, 15.66-15.85 and 38.70-39.14, respectively. Sulfide separates have 206Pb/204Pb, 207Pb/204Pb and 208Pb/204Pb values ranging from 18.03 to 18.73, 15.65 to 15.78 and 38.15 to 39.14, respectively. These Pb isotopic data indicate a clearly crustal source of Pb in the plot of 207Pb/204Pb vs. 206Pb/204Pb. Total REE (ΣREE) contents of country shale and dolostone whole-rock samples are 2.63 ppm and 0.72-86.2 ppm with δEu values are 2.79 and 0.34-0.70, respectively. Pyrite, sphalerite, galena and calcite samples have ΣREE contents of 5.3-36.4 ppm, 0.29-3.39 ppm, 0.52 ppm and 22.0-41.1 ppm, respectively, and δEu values of 0.64-0.86, 0.94-2.86, 0.32 and 0.21-0.45, respectively. These rare earth

  1. Phonon dynamics of Zn(Mg,Cd)O alloy nanostructures and their phase segregation

    NASA Astrophysics Data System (ADS)

    Ghosh, Manoranjan; Dilawar, Nita; Bandyopadhyay, A. K.; Raychaudhuri, A. K.

    2009-10-01

    In this paper we report phonon dynamics in chemically synthesized Zn1-xMgxO (0≤x≤0.07) and Zn1-yCdyO (0≤y≤0.03) alloy nanostructures of sizes ˜10 nm using nonresonant Raman and Fourier transformed infrared spectroscopy. Substitution by Mg makes the unit cell compact while Cd substitution leads to unit cell expansion. On alloying, both A1 (LO) and E1 (LO) mode of wurtzite ZnO show blueshift for Zn1-xMgxO and redshift for Zn1-yCdyO alloy nanostructures due to mass defect and volume change induced by the impurity atoms. Significant shift has been observed in E1 (LO) mode for Zn1-xMgxO (73 cm-1 for x=0.07) and Zn1-yCdyO (17 cm-1 for y =0.03) nanostructures. The variation in Zn(Mg,Cd)-O bond length determined from the blue- (red-) shift of IR bands on alloying with Mg (Cd) is consistent with their respective ionic sizes and the structural changes predicted by x-ray diffraction study. However, on progressive alloying one can detect phase segregation (due to presence of interstitial Mg and Cd ions) in the alloy nanostructures for relatively higher Mg and Cd concentrations. This is confirmed by the gradual absence of the characteristic IR and Raman bands of wurtzite ZnO near 400-600 cm-1 as well as by x-ray and TEM studies.

  2. Determination of Cd, Cr and Pb in phosphate fertilizers by laser-induced breakdown spectroscopy

    NASA Astrophysics Data System (ADS)

    Nunes, Lidiane Cristina; de Carvalho, Gabriel Gustinelli Arantes; Santos, Dario; Krug, Francisco José

    2014-07-01

    A validated method for quantitative determination of Cd, Cr, and Pb in phosphate fertilizers by laser-induced breakdown spectroscopy (LIBS) is presented. Laboratory samples were comminuted and homogenized by cryogenic or planetary ball milling, pressed into pellets and analyzed by LIBS. The experimental setup was designed by using a Q-switched Nd:YAG at 1064 nm with 10 Hz repetition rate, and the intensity signals from Cd II 214.441 nm, Cr II 267.716 nm and Pb II 220.353 nm emission lines were measured by using a spectrometer furnished with an intensified charge-coupled device. LIBS parameters (laser fluence, lens-to-sample distance, delay time, integration time gate, number of sites and number of laser pulses per site) were chosen after univariate experiments with a pellet of NIST SRM 695 (Trace Elements in Multi-Nutrient Fertilizer). Calibration and validation were carried out with 30 fertilizer samples from single superphosphate, triple superphosphate, monoammonium phosphate, and NPK mixtures. Good results were obtained by using 30 pulses of 50 J cm- 2 (750 μm spot size), 2.0 μs delay time and 5.0 μs integration time gate. No significant differences between Cd, Cr, and Pb mass fractions determined by the proposed LIBS method and by ICP OES after microwave-assisted acid digestion (AOAC 2006.03 Official Method) were found at 95% confidence level. The limits of detection of 1 mg kg- 1 Cd, 2 mg kg- 1 Cr and 15 mg kg- 1 Pb and the precision (coefficients of variation of results ranging from 2% to 15%) indicate that the proposed LIBS method can be recommended for the determination of these analytes in phosphate fertilizers.

  3. [Immobilization remediation of Cd and Pb contaminated soil: remediation potential and soil environmental quality].

    PubMed

    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.

  4. [Immobilization remediation of Cd and Pb contaminated soil: remediation potential and soil environmental quality].

    PubMed

    Sun, Yue-Bing; Wang, Peng-Chao; Xu, Ying-Ming; Sun, Yang; Qin, Xu; Zhao, Li-Jie; Wang, Lin; Liang, Xue-Feng

    2014-12-01

    A pot experiment was conducted to investigate the immobilization remediation effects of sepiolite on soils artificially combined contamination by Cd and Pb using a set of various pH and speciation of Cd and Pb in soil, heavy metal concentration in Oryza sativa L., and soil enzyme activity and microbial quantity. Results showed that the addition of sepiolite increased the soil pH, and the exchangeable fraction of heavy metals was converted into Fe-Mn oxide, organic and residual forms, the concentration of exchangeable form of Cd and Pb reduced by 1.4% - 72.9% and 11.8% - 51.4%, respectively, when compared with the control. The contents of heavy metals decreased with increasing sepiolite, with the maximal Cd reduction of 39.8%, 36.4%, 55.2% and 32.4%, respectively, and 22.1%, 54.6%, 43.5% and 17.8% for Pb, respectively, in the stems, leaves, brown rice and husk in contrast to CK. The addition of sepiolite could improve the soil environmental quality, the catalase and urease activities and the amount of bacteria and actinomycete were increased to some extents. Although the fungi number and invertase activity were inhibited compared with the control group, it was not significantly different (P > 0.05). The significant correlation between pH, available heavy metal content, urease and invertase activities and heavy metal concentration in the plants indicated that these parameters could be used to evaluate the effectiveness of stabilization remediation of heavy metal contaminated soil. PMID:25826946

  5. Cancer Cell Targeting Using Folic Acid/Anti-HER2 Antibody Conjugated Fluorescent CdSe/CdS/ZnS-Mercaptopropionic Acid and CdTe-Mercaptosuccinic Acid Quantum Dots.

    PubMed

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

    2016-01-01

    CdSe/CdS/ZnS and CdTe quantum dots (QDs) were synthesized by successive ion layer adsorption and reaction (SILAR) technique and direct aqueous synthesis respectively using thiol stabilizers. Synthesized CdSe/CdS/ZnS and CdTe QDs stabilized with 3-mercaptopropionic acid (MPA) and mercaptosuccinic acid (MSA) were used as fluorescent labels after conjugation with folic acid (FA) and anti-HER2 antibodies. Photoluminescence quantum yield of folated CdSe/CdS/ZnS-MPA and CdTe-MSA QDs was 59% and 77% than that of non-folated hydrophilic QDs. The folate receptor-mediated delivery of folic acid-conjugated CdTe-MSA and CdSe/CdS/ZnS-MPA QDs showed higher cellular internalization as observed by confocal laser scanning microscopic studies. Folated and non-folated CdTe-MSA QDs were highly toxic and exhibited only 10% cell viability as compared to > 80% cell viability with CdSe/CdS/ZnS-MPA QDs over the concentration ranging from 3.38 to 50 pmoles. Immunohistochemistry (IHC) results of human breast cancer tissue samples showed positive results with anti-HER2 antibody conjugated CdSe/CdS/ZnS-MPA QDs with better sensitivity and specificity as compared to conventional IHC analysis using diaminobenzedene staining. PMID:27398438

  6. Single and joint effects of Zn and Cd on Porcellio scaber (Crustacea, Isopoda) exposed to artificially contaminated food.

    PubMed

    Zidar, Primoz; Van Gestel, Cornelis A M; Strus, Jasna

    2009-11-01

    This study aimed at determining effects of Zn, Cd and their equitoxic mixtures on metal assimilation and food consumption of the terrestrial isopod Porcellio scaber, in relation to metal availability in the food. Cd was four times less water-extractable than Zn. Cd or Zn extractability was affected neither by metal concentration nor by the presence of the other metal. In single metal exposures, assimilation efficiency (AE) was up to five times higher for Cd than for Zn. In a mixture, AE of Cd significantly increased at low mixture concentrations and decreased at high mixture concentrations. AE of Zn significantly increased at intermediate mixture concentrations. Effects of the Zn and Cd mixture on food consumption were additive (28-day EC(50,total)=1.10TU; EC(50,water-extractable)=1.18TU) when based on total and water-extractable concentrations but antagonistic when related to internal metal concentrations in the isopods (EC(50,internal)=1.40TU).

  7. Ultrasonic semi-solid coating soldering 6061 aluminum alloys with Sn-Pb-Zn alloys.

    PubMed

    Yu, Xin-ye; Xing, Wen-qing; Ding, Min

    2016-07-01

    In this paper, 6061 aluminum alloys were soldered without a flux by the ultrasonic semi-solid coating soldering at a low temperature. According to the analyses, it could be obtained that the following results. The effect of ultrasound on the coating which promoted processes of metallurgical reaction between the components of the solder and 6061 aluminum alloys due to the thermal effect. Al2Zn3 was obtained near the interface. When the solder was in semi-solid state, the connection was completed. Ultimately, the interlayer mainly composed of three kinds of microstructure zones: α-Pb solid solution phases, β-Sn phases and Sn-Pb eutectic phases. The strength of the joints was improved significantly with the minimum shear strength approaching 101MPa.

  8. Ultrasonic semi-solid coating soldering 6061 aluminum alloys with Sn-Pb-Zn alloys.

    PubMed

    Yu, Xin-ye; Xing, Wen-qing; Ding, Min

    2016-07-01

    In this paper, 6061 aluminum alloys were soldered without a flux by the ultrasonic semi-solid coating soldering at a low temperature. According to the analyses, it could be obtained that the following results. The effect of ultrasound on the coating which promoted processes of metallurgical reaction between the components of the solder and 6061 aluminum alloys due to the thermal effect. Al2Zn3 was obtained near the interface. When the solder was in semi-solid state, the connection was completed. Ultimately, the interlayer mainly composed of three kinds of microstructure zones: α-Pb solid solution phases, β-Sn phases and Sn-Pb eutectic phases. The strength of the joints was improved significantly with the minimum shear strength approaching 101MPa. PMID:26964943

  9. Growth of CdZnTe Crystals for Radiation Detector Applications by Directional Solidification

    NASA Technical Reports Server (NTRS)

    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

  10. Paleomagnetic Age for the World-class Century Zn-Pb-Ag Deposit, Australia

    NASA Astrophysics Data System (ADS)

    Kawasaki, K.; Symons, D. T.; Dawborn, T.

    2009-05-01

    Paleomagnetic results are reported for the Century Zn-Pb-Ag SEDEX deposit in northwestern Queensland, Australia. The stratiform mineralization occurs in fine parallel lamellae in ˜1595 Ma siderite-rich siltstones and black shales of the upper Lawn Hill Formation in the Proterozoic McNam