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