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  • 1995-1999  (456)
  • 1996  (456)
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  • 1995-1999  (456)
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  • 1
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Severe soil contamination is often encountered at wood-impregnation plants due to spills, dripping and deposition of sludge associated with dissolved salts of copper, chromium and arsenic (CCA). Soil samples from a CCA-plant in southern Norway were analysed via a factorial extraction design to investigate mobilisation of contaminated soils. Various concentrations of organic acids, sea-salts, and pH showed that contaminants were not stable, and could be mobilised to the aqueous phase. To further investigate mobilisation of impregnation salts, soil solution collectors were installed at various depths at the site. Concentrations varied considerably. Hydrological changes revealed elevated levels of dissolved salts, which agree with the factorial experiment. Soil chemical processes (not total solid-phase concentrations) dominated the mobilisation and subsequent leaching. Soil solutions were tested for changes in toxicity by chemical analysis and degree of inhibition of luminescence in Vibrio fisheri (Microtox). Changes in toxicity corresponded to changes in soil solution.
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  • 2
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The clay mineral montmorillonite has been tested as modifier for the carbon paste electrode with a novel electrode modification technique. The differential pulse voltammetric determination of copper(II) by means of this modified carbon paste electrode has been studied. A detection limit of 4×10-8 mol/l has been achieved after 10 min preconcentration under open circuit conditions with subsequent anodic stripping voltammetry. The calibration curve for Cu(II) is linear in the range of 4×10-8–8×10-7 mol/l. Pb interferes in a 10-fold molar and Cd and Hg in a 100-fold molar excess. The interference by humic ligands is significant.
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  • 3
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract An Energy-dispersive Miniprobe Multielement Analyzer (EMMA) was designed and constructed for sensitive, rapid, and non-destructive analysis of trace elements (As, Cr, Cu, Fe, Ga, Ge, Hf, Mn, Ni, Pb, Rb, Se, Sr, Th, Y, U, Zn) in small (e.g. 50 μm) samples such as individual mineral grains from rocks. An alternative configuration of the EMMA instrument is described here for use with larger samples such as powders of coal, soil, sediments, and plant materials. To minimize heterogeneity problems, a larger X-ray beam size (0.1 × 6 mm) was used by installing a different collimator, and the sample holder rotated 25 times per minute. Using this approach, Rb, Sr, Cu, Zn and Pb were measured in peat samples collected from bogs in Switzerland and northern Scotland. The detection limit for Pb, for example, is approximately 0.3 μg/g which is one order of magnitude better than conventional XRF analyzers. For comparison, Pb was also measured in acid digests of the same samples using GFAAS. The Pb results obtained using EMMA are comparable to the GFAAS data for the continental peat samples. However, in the Cl-rich samples from the maritime bogs, the GFAAS signal was strongly suppressed, and an accurate comparison of the two methods was not possible. The EMMA technique, therefore, has three advantages over conventional GFAAS: first, no sample dissolution is required; second, several elements of interest are determined simultaneously; and third, the EMMA technique is not subject to matrix interferences.
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  • 4
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Possibilities to increase the sensitivity of stripping analysis by optimising the hydrodynamic conditions of the solution during the deposition and rest period are evaluated. Rotation rates as high as 13 000 rpm can be applied during the deposition step at a mercury film rotating disc electrode for Zn, Cd, Pb, In and Tl determinations when 10–20 mg/l of Hg2+ for the renewal of the mercury film is added. Because of the extreme sensitivity on the properties of the mercury film in the case of Ga only 4000–5000 rpm are recommended. The highest stirring efficiencies using a magnetic stirrer are equivalent to 2500–3000 rpm when a rotating disc electrode is used. The effect of the duration of the rest period is not significant for square wave stripping voltammetry, however, analytical signals can be increased 10 and more times when potentiometric stripping analysis is applied.
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  • 5
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The classical Rothamsted Experiments allow to contribute to current research. The heavy metal content of soil and hay samples have been measured with ICP-AES from a control and a fertilized plot of the Park Grass Experiment. Today a difference of 1.2 can be observed in the pH levels of the control and fertilized plots; the pH level of the control plot has decreased about 1.0, that of the fertilized plot about 2.2 as a result of 150 years of acid deposition and fertilization. The changes in the pH levels has caused many changes in the heavy metal content of the top layer of the soil. Using different extraction methods (e.g., ammonium acetate, EDTA, and sequential analysis), the heavy metal content of different fractions have been estimated. In the control plot, the Zn, Cd and Pb content increased. In the fertilized plot, the Pb and Cd contents have also increased because of atmospheric deposition and small amounts of lead in the fertilizer. The available form of Cd and Pb increased in both the control and the fertilized plots.
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  • 6
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Concentration of 25 trace metals in mosses (Hylocomium splendens, Pleurozium schreberi and Hypnum cupressiforme) are compared with bulk deposition freights (Bergerhoff method) at 3 sites in Switzerland, one on the plateau, a second in the northern prealps and a third in the southern alps. The three moss species are interchangeable and the atmospheric background deposition can be estimated with sufficient accuracy for Ag, Al, As, Cd, Ce, Co, Cr, Cu, Fe, Ga, Ge, La, Li, Mo, Nb, Ni, Pb, Th, Ti, U, V, W, Y, Zn. For Hg this study does not give definite results. No seasonal differences in moss concentrations from spring to autumn can be shown.
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  • 7
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Equilibrium diffusion chambers (“peepers”) have been constructed to collect anoxic pore waters in bogs without degassing and/or oxidizing the samples. These samplers have been constructed of Plexiglass, either as a long board with a series of sampling chambers for close interval analyses near the surface of a bog, or as single chambers inserted at greater depths (1 to 6 m). Prior to installation, the chambers have been filled with deaerated, deionized water, and have been covered by a 0.2 μm membrane filter; this membrane allows the dissolved constituents in the waters to equilibrate with the deionized water in the chamber by diffusion. The samplers have been allowed to equilibrate in the bog for 4 to 6 weeks. Thereafter, they have been withdrawn into N2-filled glove bags. Individual chambers have been sampled in the field by inserting a syringe through the glove bag; these syringes have been used immediately upon the arrival in the lab to analyze volatile and redox-sensitive species by ion chromatography. The effectiveness of this sampling approach has been demonstrated by measuring the concentrations of the dominant volatile acids in these waters (H2CO3) and two redox sensitive species (Fe2+ and HS–). The procedure described here should be applicable also to trace metal speciation studies, provided that appropriate checks are made for all possible sources of contamination.
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  • 8
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The chromium and nickel uptake of ryegrass has been examined in pot experiments in extremely different soils, poor sandy and fertile black chernozem. The effect of calcium carbonate doses and nitrogen supply on heavy metal uptake of the plant has been studied for chromium and nickel loadings (0–100 mg/kg Cr3+ or Ni2+) applied as inorganic salts. The ability to uptake Cr3+ and Ni2+ differs significantly and is highly affected by the characteristics of soils, and depends on the metal investigated. The heavy metal uptake of the plant differs significantly in acid, colloid deficient sandy soils; while artificial chromium contamination did not modify the dry-matter production in the pots in either soil, a large quantity of nickel reduced the yields significantly. Nitrogen application did not change significantly the uptake of heavy metals. Lime application reduced the Ni2+ uptake of plants considerably, especially in sandy soil. In case of a calcium carbonate addition the dry-matter production of the plant was not affected by nickel. In chernozem soil the effect of lime application – i.e., the reduction of nickel uptake – was of a lesser degree. The significantly lesser Cr3+ uptake was further limited by a calcium carbonate application for both soils studied. A graphic presentation of these effects is given.
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  • 9
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The determination of heavy metals in concentrations less than 10-6 mol/L by ion chromatography with conductivity detection requires a preconcentration step. Therefore, a special electrochemical equipment and method was developed for the on-line preconcentration of the divalent metals Ni, Co, Zn and Cd and their subsequent ion chromatographic determination. The loop of the injection valve of an ion chromatograph was replaced by an electrochemical flow-through-cell with a gold working electrode, a platinum auxiliary electrode and a silver/silver sulphate reference electrode. The preconcentration step consists of the deposition of the reduced metals on the electrode surface during a continuous pumping of the sample solution through the cell. After switching of the mobile phase through the cell, the analytes are injected after their reoxidation directly into the mobile phase. A new preconcentration step is simultaneously possible during the actual chromatographic run. An effective separation of the analytes from the matrix is also possible with the proposed system. A maximum of metal ion accumulation was obtained after 120 min in the galvanostatic mode on a gold tube electrode. The detection limits for Co(II), Ni(II), Zn(II) and Cd(II) were improved by a factor of 7.7, 10.4, 11.2, 14.0, respectively, and were in the 0.1 μmol/L concentration range with a RSD of 2–6%. The accumulation of metal ions was disturbed in the presence of Cr(III).
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  • 10
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Trace metals and nutrients were monitored voltammetrically and spectrophotometrically during a one-year period (1992/93) in the filtered fraction of coastal surface seawaters sampled with a monthly frequency at 6 different sites in the Gulf of Trieste (Northern Adriatic Sea), to evaluate the degree of pollution in an area receiving industrial, agricultural and urban wastes. The sites devoted to hatcheries of edible mussels are of particular interest. A multivariate statistical analysis of the collected concentration data by the principal component method allows to identify the sources and typology of pollution, and to discriminate between the quality of waters at the different sampling sites. The coastal waters in the Gulf of Trieste seem to be comparable to, or better than, waters of analogous areas in the Mediterranean Sea.
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