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  • 1
    ISSN: 1432-0495
    Keywords: Key words Heavy metals ; Base metals ; Smelter ; Anthropogenic contamination ; Chemical partitioning ; Soil ; Particulate emissions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract  Trace element geochemistry of humus (〈0.425 mm) and till (〈0.002 mm) collected in the Flin Flon-Snow Lake area, northern Manitoba and Saskatchewan, provides a regional context for assessing smelter contamination in the environment. The area includes a Cu-Zn smelter known to discharge As, Cd, Cu, Fe, Hg, Pb, and Zn. In this study, sequential extraction analyses, scanning electron microscopy and x-ray diffraction analyses were used on a suite of samples to determine: (1) the chemical and physical characteristics of heavy metals in surficial sediments related to distance from the smelter, (2) criteria for assessing the relative contribution of these metals from natural and anthropogenic sources, and (3) the potential of these metals for remobilization in the environment. Humus geochemistry reflects the anthropogenic and natural component of heavy metal concentrations. Smelter-related elements show anomalously high values adjacent to the smelter, decreasing with distance until background values are reached at 70–104 km, depending on the element. In humus, Zn is associated primarily with labile phases; Hg with non-labile phases. Adjacent to the smelter, high proportions and concentrations of Zn and Hg in non-labile phases, indicative of smelter-derived particulates, are confirmed by SEM examination. The particles occur as spheres, irregular grains, and with organics. With increasing distance from the smelter, the geochemical response to bedrock composition is more obvious than the anthropogenic input. Till geochemistry reflects the natural variation imposed by bedrock composition. At highly contaminated sites (〈3 km from the smelter), increased percentages of smelter-related elements in labile phases suggests heavy metals are leached from humus to the underlying sediment.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Archives of toxicology 45 (1980), S. 53-59 
    ISSN: 1432-0738
    Keywords: 2-Acetylaminofluorene ; Dimethylnitrosamine ; 4-Nitroquinoline-1-Oxide ; Isolated rat liver cells ; DNA-repair ; Salmonella typhimurium ; Mutagenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Isolated rat liver cells are able to metabolize 2-acetylaminofluorene (2-AAF) to reactive species, capable of producing mutagenic effects in Salmonella typhimurium TA 1538 and evoking unscheduled DNA synthesis within the hepatocytes. Indications are presented, that these genotoxic effects are caused by different reactive metabolites. Mutagenesis could be blocked almost completely by paraoxon, an inhibitor of the de-acetylation reaction, whereas induction of DNA excision repair was prevented by antagonizing the sulfation reaction by means of salicylamide.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-0738
    Keywords: Benzidine ; 2-Aminofluorene ; 2-Acetylaminofluorene ; Dimethylnitrosamine ; Diethylnitrosamine ; Isoniazid ; Cyclophosphamide ; Ethanol-induction ; Cytochrome P-450 ; N-acetylation ; Isolated rat hepatocytes ; Mutagenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effects of ethanol-feeding to rats, over a 6-week period, on the activation of genotoxic compounds of different chemical classes, requiring metabolic conversion to exert their mutagenic activity, were studied in isolated rat hepatocytes. The influence of such treatment on cytochrome P-450 content and N-acetylation in isolated hepatocytes was also investigated. Benzidine (BZ), dimethylnitrosamine (DMN), diethylnitrosamine (DEN), isoniazid (INH) and cyclophosphamide (CP) were more effectively activated to products mutagenic towards Salmonella typhimurium by hepatocytes from ethanol-pretreated rats than by hepatocytes from controls. The mutagenic potency of 2-aminofluorene (2-AF) and 2-acetylaminofluorene (2-AAF) was not influenced by ethanol pretreatment. Ethanol consumption was found to be associated with increased cytochrome P-450 content and enhanced N-acetylation in the isolated hepatocytes. Our results support the hypothesis that an alteration of the hepatic drug-metabolizing system may be responsible for the ethanol-induced increase in susceptibility to certain genotoxic compounds.
    Type of Medium: Electronic Resource
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