Physicochemical Conditioning of Dredged Heavy Metal-Polluted Sediment in Suspension

2004 ◽  
Vol 4 (3) ◽  
pp. 258-265 ◽  
Author(s):  
C. Löser ◽  
A. Zehnsdorf ◽  
K. Voigt ◽  
H. Seidel
Keyword(s):  
Heavy Metal ◽  
Polluted Sediment

Bioleaching of Heavy Metal Polluted Sediment: Influence of Sediment Properties (Part 2)

2006 ◽  
Vol 6 (4) ◽  
pp. 364-371 ◽  
Author(s):  
C. Löser ◽  
A. Zehnsdorf ◽  
P. Hoffmann ◽  
H. Seidel
Keyword(s):  
Heavy Metal ◽  
Sediment Properties ◽  
Polluted Sediment

Bioleaching of Heavy Metal Polluted Sediment: Influence of Temperature and Oxygen (Part 1)

2006 ◽  
Vol 6 (4) ◽  
pp. 355-363 ◽  
Author(s):  
C. Löser ◽  
A. Zehnsdorf ◽  
K. Görsch ◽  
H. Seidel
Keyword(s):  
Heavy Metal ◽  
Influence Of Temperature ◽  
Polluted Sediment

Remediation of heavy metal polluted sediment in the solid bed: Comparison of abiotic and microbial leaching

Chemosphere ◽  
2006 ◽  
Vol 65 (1) ◽  
pp. 9-16 ◽  
Author(s):  
Christian Löser ◽  
Andreas Zehnsdorf ◽  
Kati Görsch ◽  
Heinz Seidel
Keyword(s):  
Heavy Metal ◽  
Polluted Sediment ◽  
Microbial Leaching

Remediation of heavy metal polluted sediment by suspension and solid-bed leaching: Estimate of metal removal efficiency

Chemosphere ◽  
2007 ◽  
Vol 66 (9) ◽  
pp. 1699-1705 ◽  
Author(s):  
Christian Löser ◽  
Andreas Zehnsdorf ◽  
Petra Hoffmann ◽  
Heinz Seidel
Keyword(s):  
Heavy Metal ◽  
Removal Efficiency ◽  
Metal Removal ◽  
Polluted Sediment

scholarly journals Status of heavy metal in sediments of the Turag river in Bangladesh

2016 ◽  
Vol 27 (2) ◽  
pp. 78-85 ◽  
Author(s):  
KM Mohiuddin ◽  
MS Islam ◽  
S Basak ◽  
HM Abdullah ◽  
I Ahmed
Keyword(s):  
Heavy Metal ◽  
Sediment Quality ◽  
Pollution Prevention ◽  
Enrichment Factors ◽  
River Pollution ◽  
Pollution Load Index ◽  
Geochemical Background ◽  
Pollution Load ◽  
Polluted Sediment ◽  
Fe And Mn

The experiment was conducted to appraise the level of Cr, Pb, Cd, Ni, Zn, Cu, Fe and Mn contamination in 15 sediment samples of upstream of Turag river, at the Department of Agricultural Chemistry, Bangladesh Agricultural University, Mymensingh. The concentrations of Cr, Pb, Cd, Ni, Zn, Cu, Fe and Mn were 178.0, 18.3, 0.8, 155.4, 194.1, 54.8, 13679 and 5501.6 µg g-1 and the pH and EC ranged from 2.01-7.85 and 391-3910µS cm-1, respectively. Heavy metal concentrations were compared with geochemical background and standard values of previous report on the Turag and other rivers in Bangladesh. The average concentrations of Cr, Zn and Ni in sediments of the Turag are almost twice of the geochemical background i.e. average worldwide shale standard and continental upper crust. Cadmium is about three times higher than the geochemical background values.  Chromium and Ni concentration exceeded the severe effect level (SEL), where as Cd, Zn and Cu exceeded toxicity reference values (TRV). The average Enrichment Factors (EFc) for Mn, Cd, Cr and Ni reflected moderate to extremely contaminated pollution. The pollution load index (PLI) varied from 1.65 to 3.21. The geoaccumulation index (Igeo) for Mn of 11 locations and Cd for a single location were greater than 2.0, and exhibited moderately to strongly polluted sediment quality. The Igeo for Zn in two locations and Ni in one location were greater than 1.0, indicated moderately polluted sediment quality. Sediment pollution load signaled alarming condition for city dwellers and aquatic ecosystem of the Turag river. Pollution sources to be sealed immediately and continuous monitoring on pollution prevention and cleanup operation is suggested.Progressive Agriculture 27 (2): 78-85, 2016

scholarly journals pH Effect on Heavy Metal Release from a Polluted Sediment

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Yanhao Zhang ◽  
Haohan Zhang ◽  
Zhibin Zhang ◽  
Chengying Liu ◽  
Cuizhen Sun ◽  
...  
Keyword(s):  
Heavy Metal ◽  
Sequential Extraction ◽  
River Water ◽  
Ph Effect ◽  
Residual Fraction ◽  
Leaching Test ◽  
Metal Release ◽  
Polluted Sediment ◽  
Leaching Solution ◽  
Heavy Metal Release

The performance of Cd, Ni, and Cu release from river sediment at different pH was investigated by a leaching test using deionised water and river water as leachants. Visual MINTEQ geochemical software was used to model the experimental results to predict heavy metal release from sediments. The distribution and speciation of heavy metals in the sediments after leaching test were analyzed by Tessier sequential extraction. Leaching test results showed that the release amounts of Cd, Ni, and Cu are in the range of 10.2–27.3 mg·kg−1, 80.5–140.1 mg·kg−1, and 6.1–30.8 mg·kg−1, respectively, with deionised water as leachant at different pH. As far as the river water was used as the leaching solution in the test, the results show similar metal leaching contents and tendencies to that of the deionised water as leaching solution. The results of Tessier sequential extraction indicate that Cd of residual fraction easily forms obvious precipitate under the acidic condition, especially in the range of pH 0–4 with the residual of Cd over 50% of the total Cd in the sediment. The exchangeable content of Ni decreases with the increase of pH under the range of 0–5. The Fe-Mn oxide fraction of Cu in the sediments changes significantly from pH 0 to pH 9. Based on the effect of pH on the leaching of Cd, Ni, and Cu from the polluted sediment in the tests, more accurate information could be obtained to assess the risk related to metal release from sediments once it is exposed to the changed acid/alkali water conditions.

Complementary Z-Contrast Imaging and Digital Image Processing

1985 ◽  
Vol 43 ◽  
pp. 304-305
Author(s):  
K. N. Colonna ◽  
G. Oliphant
Keyword(s):  
Image Processing ◽  
Heavy Metal ◽  
Digital Image Processing ◽  
Digital Image ◽  
Biological Tissue ◽  
Biological Imaging ◽  
Tissue Preparation ◽  
Contrast Imaging ◽  
Imaging Tool ◽  
Z Contrast

Harmonious use of Z-contrast imaging and digital image processing as an analytical imaging tool was developed and demonstrated in studying the elemental constitution of human and maturing rabbit spermatozoa. Due to its analog origin (Fig. 1), the Z-contrast image offers information unique to the science of biological imaging. Despite the information and distinct advantages it offers, the potential of Z-contrast imaging is extremely limited without the application of techniques of digital image processing. For the first time in biological imaging, this study demonstrates the tremendous potential involved in the complementary use of Z-contrast imaging and digital image processing.Imaging in the Z-contrast mode is powerful for three distinct reasons, the first of which involves tissue preparation. It affords biologists the opportunity to visualize biological tissue without the use of heavy metal fixatives and stains. For years biologists have used heavy metal components to compensate for the limited electron scattering properties of biological tissue.

Recent Progress In High-Resolution Shadowing For Biological Transmission Electron Microscopy

1990 ◽  
Vol 48 (1) ◽  
pp. 510-511 ◽  
Author(s):  
Heinz Gross ◽  
Katarina Krusche ◽  
Peter Tittmann
Keyword(s):  
Heavy Metal ◽  
High Resolution ◽  
Freeze Drying ◽  
Atmospheric Conditions ◽  
Vacuum Equipment ◽  
Transmission Electron ◽  
Gas Atmosphere ◽  
Gas Molecules ◽  
Residual Gas ◽  
Backing Layer

Freeze-drying followed by heavy metal shadowing is a long established and straight forward approach to routinely study the structure of dehydrated macromolecules. Very thin specimens such as isolated membranes or single macromolecules are directly adsorbed on C-coated grids. After rapid freezing the grids are transferred into a suitable vacuum equipment for freeze-drying and heavy metal shadowing.To improve the resolution power of shadowing films we introduced shadowing at very low specimen temperature (−250°C). To routinely do that without the danger of contamination we developed in collaboration with Balzers an UHV (p≤10-9 mbar) machine (BAF500K, Fig.2). It should be mentioned here that at −250°C the specimen surface acts as effective cryopump for practically all impinging residual gas molecules from the residual gas atmosphere.Common high resolution shadowing films (Pt/C, Ta/W) have to be protected from alterations due to air contact by a relatively thick C-backing layer, when transferred via atmospheric conditions into the TEM. Such an additional C-coat contributes disturbingly to the contrast at high resolution.

Heavy Metal Tales

2008 ◽  
Vol 42 (2) ◽  
pp. 24
Author(s):  
WILLIAM G. WILKOFF
Keyword(s):  
Heavy Metal
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