Eﬀect of sulfur-perlite containing waste on clover productivity and heavy metal translocation (Cd, Pb, Zn).

<p>Soil contamination by heavy metals causes metal accumulation by plants, which leads to the degradation of plants communities and migration of toxicants with food chains to man. Therefore, the investigation of heavy metal concentration in soils of urban areas is an urgent scientific task. This study aims to examine the translocation of heavy metals from urban soils to herbs in Tyumen (Russian Federation).&#160; Soil surface layer was collected at control site, near the highway as well as from areas with metallurgical, motor building, oil refinery and battery manufactory plants in Tyumen. Meadow grass, red clover, wild vetch, chamomile and coltsfoot were collected at all examined sites. &#160;The mobile and acid-soluble heavy metal fractions in soils, as well as the heavy metal contents in plants, were determined by atomic absorption spectrophotometry. The bioconcentration factor was estimated as the ratio of the amount of heavy metals in soils to that in plants. The study was performed during three-year period from 2017 to 2019. Heavy metal concentrations in urban soils were higher than those at the control site by 20% and by up to 10 times. The greatest heavy metal accumulation in both soils and plants was found at the battery manufacturing and metallurgical plants, exceeding the control levels of Pb and Fe by 2-17 times. The Cu, Fe and Mn contents in soil were positively correlated with those in plants. Heavy metal translocation by the plants was species-specific. The percentages of the mobile heavy metal fractions decreased in the following order: Mn>Zn>Cu>Fe. Heavy metal accumulation in plants in the urban sites compared to that at the control site decreased in the following order: Fe>Zn>Cu>Mn>Pb>Cd. Coltsfoot exhibited the highest Fe, Mn, and Zn accumulation, which exceeded the control levels by 17, 5, and 3.5 times, respectively. The heavy metal bioconcentration factors, indicators of translocation, decreased in the following order: Cu>Zn>Cd>Pb>Mn>Fe. The heavy metal translocation suggests the need to relocate industrial facilities to outside the city. Future monitoring of the study area is needed to ensure its long-term ecological safety.</p>

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Complementary Z-Contrast Imaging and Digital Image Processing

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100118394 ◽

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.

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

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100181300 ◽

1990 ◽

Vol 48 (1) ◽

pp. 510-511 ◽

Cited By ~ 1

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.

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