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Moyo S Mujuru M McCrindle RI Mokgalaka-Matlala N 《Journal of environmental monitoring : JEM》2011,13(5):1488-1494
Samples of coal were collected from different seams at a South African coal mine and comparative leaching experiments were carried out under various pH conditions and times to investigate the leaching behavior and potential environmental impact of possibly hazardous elements such as As, Cd, Co, Cr, Mn, Ni, Pb, Th and U. The calculated leaching intensities, sequential extraction results and cumulative percentages demonstrate that the leaching behavior of the elements is strongly influenced by the pH, the leaching time and the properties and occurrences of the elements. The leached concentrations of As, Cd, Co, Cr, Mn, Ni and Pb exceeded the maximum concentrations recommended by the Environmental Protection Agency (EPA) for surface water. 相似文献
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Woody shrub encroachment severely impacts on the hydrological and erosion response of rangelands and abandoned cultivated
lands. These processes have been widely investigated at various spatial scales, using mostly field experimentation. The present
study used remote sensing to investigate spatial and temporal patterns of soil erosion and encroachment by a woody shrub species,
Pteronia
incana, in a catchment in Ngqushwa district, Eastern Cape Province, South Africa between 1998 and 2008. The extreme categories of
soil erosion and shrub encroachment were mapped with higher accuracy than the intermediate ones, particularly where lower
spatial resolution data were used. The results showed that soil erosion in the worst category increased simultaneously with
dense woody shrub encroachment on the hill slopes. This trend is related to the spatial patterning of woody shrub vegetation
that increases bare soil patches—leading to runoff connectivity and concentration of overland flow. The major changes in soil
erosion and shrub encroachment analysed during the 10-year period took place in the 5–9° slope category and on the concave
slope form. Multi-temporal analyses, based on remote sensing, can extend our understanding of the dynamics of soil erosion
and woody shrub encroachment. They may help benchmark the processes and assist in upscaling field studies. 相似文献
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