Variations and Correlations Among Concentrations of Heavy Metal in the Selected Industrial Settings in Major Cities of Nigeria

Abstract

The study investigated the variation and correlations among the concentrations of heavy metals in the selected industrial settings in major cities of Nigeria. The industrial effluent samples were collected from the selected manufacturing/processing industries in Obagi Flow Station in Rivers State, Adire Kampala market in Abeokuta in Ogun State; Leather Research Institute in Zaria in Kaduna State, Berger and Dulux paints in Ikeja and Dynamics Battery Company in Ikeja in Lagos State; from which the laboratory analyses were carried out on Mercury (Hg), Lead (Pb), Cobalt (Co), Nickel (Ni), Chromium (Cr) and Cadmium (Cd) using Atomic Absorption Spectrophotometer (AAS). The industrial effluents were collected from 4 points in each station; this includes the direct effluent to the drain, the point of entry into the receiving water body,500 meters downstream the point of entry and 500meters upstream the point of entry(control). Findings revealed that The result also indicate that the nature of industrial activity influenced the level of some heavy metals in the industrial effluent. The concentration of Cr was significantly higher (p < 0.05) in the industrial effluent from the leather industry in Zaria than the concentration in the effluent from other industries. Significantly higher levels (p < 0.05) of Cd and Ni were also found in Kaduna chemical and paint industry than in the effluent water discharged from other types of industrial activities, while significantly lower levels of Pb and Co (p < 0.05) were recorded in Abeokuta. Furthermore, the concentration of Cd, Cr, Hg and Ni in the industrial effluents showed no significant difference (p<0.05) between the point of discharge and the control, while Pb and Co were significantly lower in the control. The relationship between Cobalt and Nickel in the industrial effluents showed a very high and significant correlation (r= 0.785; p<0.01). The study concluded that the concentrations of Cd, Cr, Hg and Ni in the industrial effluents showed no significant difference between the point of discharge and the control, while Pb and Co were significantly lower in the control. The significant correlations among some heavy metals are an indication that they could co-exist to generate potential combined environmental and health risks. The study recommended among others that the determination of heavy metals in aquatic organisms be carried out in the study area in order to provide possible evidence of bio-accumulation of these heavy metals in the organisms.