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  • 1
    ISSN: 1432-0495
    Keywords: Key words Agrochemical ; Heavy metal contamination ; Natural enrichment ; PFA
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Present concentrations and distributions of heavy metals through profiles, surface soil, and stream sediment samples in the Hunchun area, north-eastern China, were investigated to determine the elemental background values. This study also aims to characterize potentially toxic materials such as pulverized fly ash (PFA) from power stations or ash and slag from coal used domestically in urban areas, agrochemicals applied inappropriately, and urban sewage sludges from Hunchun City, as well as to ascertain the possibility of natural enrichment through site characterization by mineralogical and geochemical investigation. The distribution of contaminants in the alluvial soils (fluvisol) of this area has been influenced by several interacting factors. The parent alluvial materials from weathered products of amphiboles have made coatings such as ferrihydrite, goethite, and hematite. This natural inheritance factor is supported by the fact that the concentrations of weak acid-extractable (plant-available) heavy metals are very low, except for Fe and Mn. However, in agricultural soils and adjacent stream sediments, an anthropogenic input of Cd, Pb, Ni and Cr by agrochemicals is strongly suggested. Also, F contamination by coal combustion and the dissolution of F-bearing minerals could cause some future problems. Wide distribution and significantly high concentrations of Cd, Fe, Mn, and F in soils throughout the combination of pollutants originating from lithogenic and the anthropogenic sources pose potential problems in utilizing water resources.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Geophysical journal international 108 (1992), S. 0 
    ISSN: 1365-246X
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: The conventional image-formation technique of high-resolution SAR synthetic aperture radar (SAR) data has utilized correlation in the range-Doppler domain. An alternative, more recent approach, in the SAR image-formation algorithm exploits downward extrapolation of the wavefield in the f-k domain to perform not only azimuth compression but also simultaneous range-curvature corrections, with improved quality of the final image.In this paper, a new approach to SAR data processing, based on the inverse scattering and the Kirchhoff approximation, is described and tested. The complex backscattering coefficient can also be estimated by this new approach provided the surface scattering is dominant. The final inversion formula is designed to exploit f-k domain computation in an analogous manner to seismic Born inversion. Digital simulations using one- and multiple-point target models are presented to demonstrate the performance of the proposed method.
    Type of Medium: Electronic Resource
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