Quantification of Heavy Metals in Soil and Water Samples from Major Abattoirs Located in Ibadan, Oyo State, Nigeria

Abstract

The release of toxic waste materials into the environment poses serious harm that contributes to various diseases. This study assessed the heavy metal contents of soil and water samples collected from residential areas surrounding two major abattoirs in Akinyele and Oranyan, Ibadan, Nigeria. Samples were collected from identified spots in residential areas closest to each abattoir and control samples were taken from different locations. The soil samples were air-dried, ground, sieved and digested with aqua regia. Heavy metals namely Manganese (Mn), Iron (Fe), Zinc (Zn), Cadmium (Cd), Copper (Cu), and Lead (Pb) were determined using atomic absorption spectrophotometer (AAS). Data was analyzed using SPSS 19.0 and results were reported in mean±SD. Results from water analysis were in the order Fe>Mn>Zn>Cu and Fe>Zn>Mn>Cu while it was Fe>Zn>Pb>Cu>Mn>Cd and Fe>Zn>Mn> Cu>Pb>Cd in soil samples from Akinyele and Oranyan respectively. All the heavy metals were significantly higher than at the control site and above permissible limits of WHO/SON. The concentration of Fe was highest in the soil and water samples from both locations. The Fe level from Oranyan was higher than that from Akinyele abattoir. The Cd and Pb were below detectable limit from both abattoirs.  A strong positive correlation (r =0.9598 for water samples and r =0.9965 for soil samples) showed that abattoir wastes were the source of pollution. There was no significant relationship across the sampling sites. Activities within the two abattoirs impact negatively on the environment which could have harmful consequences on biodiversity including humans.