Concentration of some metallic pollutants in the Zambian environment : determination of cadmium, copper, lead and zinc in soils on and in vegetation around Kabwe

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Date
2011-04-25
Authors
Tembo, Backson
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Abstract
Environmental pollution has reached alarming proportions in Zambia. Mining and industrial activities have been responsible for water, soil, plant and air pollution. The principal objectives of this study were to determine the extent of pollution of soil and vegetation by cadmium, copper, lead and zinc and to determine the probable source of this pollution in Kabwe area. The metal contents of the soil and plant samples in Kabwe area and some farms near Lusaka were determined by atomic absorption spectrophotometry. The uptake of heavy metals by some food plants was also investigated. This was done by a comparison of the available heavy metal levels in the soils with the concentration of these metals in plants growing on these soils. The food crops investigated included maize, cabbage, rape, soyabean, tomato, banana, pawpaw, mango, groundnuts, wheat, cauliflower, carrots, onion and others. The results of analyses ranged between trace-28mg/kg Cd, 0.2-61 mg/kg Cu, 0.1-758mg/kg Pb and 0.4-234mg/Kg Zn for soil samples and between 0.1-7.3mg/kg Cd, 2.0-44mg/kg Cu, 0.8-1060mg/kg Pb and 1.9-2390mg/kg Zn for plant samples. This study showed that in Kabwe the probable source of environmental pollution is the mine. This was confirmed by the correlation coefficients(r) between soil metal content and plant metal content and distance, and between soil metal content and plant metal content. The concentration of pollutants decreased with increase in distance but was still high at a distance of 22km west of Kabwe in the direction of the prevailing wind. Plants growing near the smelter contained higher amounts of these metals than those far away. Elevated metal concentrations were partly the result of uptake via the root and partly a result of aerial deposition of metal enriched dust.
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Pollution , Pollutants
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