Publisher: Chemical Society of Nigeria

Determination of Pb, Cd, Cu and Zn Concentrations In Soil of An Abandoned City Market In Minna, Nigeria

J. O. Jacob, S. O. Salihu, Y. B. Paiko, M. A. Mahammad
KEYWORDS: heavy metals, soil, contamination, city market, Minna


Concentrations lead, cadmium, copper and zinc were determined in soil samples from a large portion of land in the central area of Minna, North-central Nigeria. The land was formerly used as the city central market. The area was divided into 20 zones from which composite samples of surface soil were collected for analysis. Control samples were also collected at a distance of 500 m from the area. Samples were digested using a 3:1 mixture of concentrated HNO3 and HClO4 acids. Recovery test on the method of digestion gave % recoveries > 95 % while in the analysis of reference materials of soil, t-test results (at 95 % confidence interval) showed that statistically there exists no significant difference between certified and obtained values. Digests were analysed using a flame atomic absorption spectrophotometer. Mean concentration of the heavy metals (µg/g dry weight) in the soil samples were Pb; 115 ± 11, Cd; 2.8 ± 1.2, Cu; 132 ± 12 and Zn; 322 ± 43. Pollution load index (PLI) values revealed that the abandoned market soil is generally more polluted with these metals due to commercial activities. The mean concentrations of the metals in soil samples were generally higher than the WHO maximum permissive limits, except for Cd. This calls for concern because of possible contamination of sources of domestic water of adjourning residential areas due to run-off and leaching. Also the area might later be utilized for other purposes posing the risk of human exposure.

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