Heavy Metals Toxicity and Chemical Assessment of Contaminated Soils With Abattoir Waste and Effluents In Southwestern Nigeria

Abstract

Increasing human population has influenced increase Abattoir facilities contributing to the escalating volume
of abattoir generated wastes and effluents that are discharged onto the environment in southwestern Nigeria.
These wastes may contain heavy metals that are toxic to humans and animals. There is limited work-done on
these potentially harmful elements (PHE's) in abattoir wastes in Nigeria. Therefore, this work examined the
potentially harmful elements (PHE's) and chemical qualities of the soils surrounding abattoirs in Oyo, Ogun
and Lagos provinces. Nine (9) composite samples from 108 contaminated soils with abattoir wastewater were
collected randomly controlled by flaying and singeing activities before they were prepared and analyzed with
Atomic Absorption Spectrometry (AAS) in ACME laboratory Canada. The pH range between 5.1±0.1 and
6.1±0.1 in Oyo, Ogun and Lagos provinces exceeding the permissible limit (pH:6-9) signifying acidic
contaminated abattoir soils . This may likely indicate the nature of the soils and other anthropogenic materials
derived from high density areas. The temperatures recorded at all the locations exceeded the maximum
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permissible limit of FEPA (26 C). Pb (0.32mg/kg) at Ijebu-Igbo abattoirs exceeded the standard value
(0.25mg/kg) that can be attributed to flaying and singeing activities in the processing and production of animal
skin (Ponmo) that is aided by burning of woods, tyres and other materials that produce carbon and soot. Copper
contents in abattoir soils at Abule-Egba (0.45mg/kg) and Ikorodu(0.41mg/kg) indicate continuous
contamination which may cause health hazards when the limit/standard (Cu-0.50 mg/kg) is exceeded.
Chromium continuous increase in Sagamu (0.31mg/kg) beyond the FEPAstandard can cause health problems.
Pb possesses weak to moderate positive correlation indicating its non chelating, prominence and controlling
capabilities from another source in that geochemical environment. Fe and Zn correlated strongly and positive
= = with Ca, Mg, Na, K, Fe, Ni and Cd with correlation coefficient of between r 0.75 to r 0.99 specifying metals
increase. The study revealed that Pb at Ijebu-Igbo abattoirs exceeding the standard value set by the Federal
Environmental Protection Agency (FEPA/FMEnv), an indication of imminent Pb toxicity with other heavy
metals which is precarious to human health.