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  • Occupational Health and Environmental Toxicology  (3)
  • sediment  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Redox processes in recent sediments of the river Meuse, The Netherlands (2000)
    Springer
    Biogeochemistry 48 (2000), S. 217-235 
    Details
    ISSN: 1573-515X
    Keywords: diagenesis ; modelling ; organic matter ; pore water ; redox ; sediment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract Pore-water concentrations of inorganic solutes were measured at four locations in a recent sedimentation area of the river Meuse in The Netherlands. The pore-water concentration profiles were interpreted using the steady state one-dimensional reaction/transport model STEADYSED1. This model explicitly accounts for the organic matter degradation pathways and secondary redox reactions. Results show that the model reproduces the measured pore-water profiles of redox species reasonably well, although significant divergence is observed for pH. The latter is due to the absence of pH buffering by CaCO3 in the model. At all locations, methanogenesis is the major pathway of organic matter degradation below 3 cm from the sediment-water interface. However, organic matter degradation rates by methanogenesis may be overestimated, because methane ebullition is not included. Differences in profiles of redox-sensitive ions among the four locations are explained by differences in depositional conditions, in particular the sediment accumulation rate and supply of organic matter.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006268325889
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Mobilisation of Heavy Metals in Contaminated Sediments in the River Meuse, The Netherlands (1999)
    Springer
    Water, air & soil pollution 116 (1999), S. 567-586 
    Details
    ISSN: 1573-2932
    Keywords: Complexation ; diffusion ; heavymetals ; mobilisation ; sediment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Due to seasonal variation in bottom-water temperature and degradation of organic matter, the depths of the redox boundaries fluctuate in sediments of the river Meuse. This is reflected by a non-steady state behaviour of heavy metals in the surface sediments. Levels of acid-volatile sulphides suggest that dissolved concentrations of heavy metals in the anoxic pore waters are determined by their respective sulphide phases. However, complexation with dissolved organic ligands may significantly increase dissolved concentrations of heavy metals. In most sediments studied, a distinct peak in dissolved concentrations of heavy metals is measured immediately below the sediment-water interface. This concentration peak may be attributed to degradation of organic matter and oxidation of sulphides. Dissolved concentration gradients indicate that upward diffusion of heavy metals from the sediment can contribute to concentrations in the surface water, although significant effects may be confined to specific locations. In addition, it is shown that release of heavy metals as dissolved species to the surface water is negligible compared to particulate-bound fluxes of heavy metals to the sediment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1005146927718
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Increased sensitivity of the non-human primate eye to microwave radiation following ophthalmic drug pretreatment (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 13 (1992), S. 379-393 
    Details
    ISSN: 0197-8462
    Keywords: microwaves ; glaucoma drugs ; primates ; corneal endothelium ; iris ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Previous studies in our laboratory have established that pulsed microwaves at 2.45 GHz and 10 mW/cm2 are associated with production of corneal endothelial lesions and with disruption of the blood-aqueous barrier in the non-human primate eye. In the study reported here we examined ocular damage in monkeys (M. mulatta and M. fascicularis) following topical treatment with one of two ophthalmic drugs (timolol maleate and pilocarpine) that preceded exposure to pulsed microwaves. Anesthetized monkeys were sham exposed or exposed to pulsed, 2.45 GHz microwaves (10 μs, 100 pps) at average power densities of 0.2, 1, 5, 10, or 15 mW/cm2 4 h a day for 3 consecutive days (respective SARs were 0.052, 0.26, 1.3, 2.6, and 3.9 W/kg). Immediately before microwave exposure, one or both eyes were treated topically with one drop of 0.5% timolol maleate or of 2% pilocarpine. Following administration of a drug, we observed a significant reduction in the power-density threshold (from 10 to 1 mW/cm2) for induction of corneal endothelial lesions and for increased vascular permeability of the iris. Diagnostic procedures (in vivo specular microscopy and fluorescein iris angiography) were performed following each exposure protocol. In addition, increased vascular permeability was confirmed with horseradish peroxidase tracer techniques. Although we did not measure intraocular temperatures in experimental animals, the results suggest that a mechanism other than significant heating of the eye is involved. Our data indicate that pulsed microwaves at an average SAR of 0.26 W/kg, if administered after pretreatment with ophthalmic drugs, can produce significant ocular effects in the anesthetized primate. 1992 Wiley-Liss, Inc.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bem.2250130505
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Effects of 2.45-GHz microwaves on primate corneal endothelium (1985)
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 6 (1985), S. 177-188 
    Details
    ISSN: 0197-8462
    Keywords: microwave irradiation ; specular microscopy ; monkey ; corneal endothelium ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Both eyes of anesthetized cynomolgus monkeys (Macaca fascicularis) were irradiated with 2.45-GHz microwaves, either pulsed or continuous wave. In vivo corneal endothelial abnormalities were observed by specular microscopy and confirmed through histologic techniques after a 16- to 48-hour postexposure period. Pulsed microwaves with an average power density of 10 mW/cm2 (equivalent to a specific absorption rate (SAR) = 2.6 W/kg) produced these effects, while levels of 20-30 mW/cm2 (equivalent to a SAR = 5.3 to 7.8 W/kg) with continuous wave irradiation were required to produce similar changes.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bem.2250060209
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Modification of membrane fluidity in melanin-containing cells by low-level microwave radiation (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Bioelectromagnetics 13 (1992), S. 131-146 
    Details
    ISSN: 0197-8462
    Keywords: microwaves ; cell membrane ; order ; melanin ; oxygen radicals ; Life and Medical Sciences ; Occupational Health and Environmental Toxicology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: The treatment of a B16 melanoma cell line with 2.45-GHz pulsed microwaves (10 mW/cm2, 10-μs pulses at 100 pps, 1-h exposure; SAR, 0.2 W/kg) resulted in changes of membrane ordering as measured by EPR (electron paramagnetic resonance) reporter techniques. The changes reflected a shift from a more fluid-like phase to a more solid (ordered) state of the cell membrane. Exposure of artificially prepared liposomes that were reconstituted with melanin produced similar results. In contrast, neither B16 melanoma cells treated with 5-Bromo-2-Deoxyuridine (3 μg/day × 7 days) to render them amelanotic, nor liposomes prepared without melanin, exhibited the microwave-facilitated increase of ordering. Inhibition of the ordering was achieved by the use of superoxide dismutase (SOD), which strongly implicates oxygen radicals as a cause of the membrane changes. The data indicate that a significant, specific alteration of cell-membrane ordering followed microwave exposure. This alteration was unique to melanotic membranes and was due, at least in part, to the generation of oxygen radicals. © 1992 Wiley-Liss, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bem.2250130207
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    Paper (German National Licenses)
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