The Effect of Heavy Metal Concentration on the Soil of Odagbo Area, Kogi State Nigeria

Abstract

The study is aimed at evaluating the effect of coal mining on the soil of Odagbo area, Kogi State, Nigeria. Twenty-eight (28) soil samples were collected each in the wet and dry seasons where twenty-one of the samples were from a mining site while seven samples were from the control site at depths of 0, 0.5, 1.0, 1.5, 2.0, 2.5 and 3.0 m respectively. The heavy metal concentration of the samples were determined using Flame Atomic Absorption Spectrophotometer (FAAS). Standard pollution indices such as I-geo and Pollution Indices were deployed to assess the level of heavy metal contamination in the soil. The result showed the order of dominance of the heavy metals monitored as Fe>Ni>Zn>Mn>Cr>Pb>Cd>Cu>Co. The mean concentration levels of all the heavy metals were lower than mean background values except Cu and Fe during the dry season. The results of the study revealed that the soil of the Odagbo is polluted by all the tested heavy metals based on the calculated PI and I-geo for the heavy metals. The PI was mostly 1≤ PI ≤ 2(moderate pollution) for all the depths except for the elevated case of copper thus indicating practically low to moderate contamination. The I-geo was mostly less than 0 at all the depths except for the elevated cases of copper, iron and zinc during the dry season and Copper and Iron during the wet season thus indicating uncontaminated condition. In conclusion, the data obtained from the study demonstrated that the distribution of metal concentration in the study area when compared to the control site was largely influenced by anthropogenic activities particular from the coal mining site.

Keywords

• soil heavy metal
• pollution index
• geo-accumulation index
• contamination