Spatial distribution of heavy metal contamination indexes in soils around auto-mechanic workshop clusters in Yenagoa metropolis, Bayelsa State, Nigeria

Abstract

Heavy metals are substances of great health and environmental concern owing to their high discharge rates into the environments in recent years, toxicity as well as persistence in nature. Several anthropogenic activities have been established to induce heavy metals into man’s environment. Studies of this nature were lacking within the study area. Thus, this work centered on establishing the distributional patterns of heavy metal contamination indexes in soils within and around auto-mechanic workshop clusters in Yenagoa Metropolis, Nigeria. Soil samples were taken and analyzed from three soil layers (0 to 15 cm, 15 to 30 cm and 30 –to 45 cm), over three distances (0 meter, 50 meters and 100 meters) from the auto-mechanic workshop clusters. Pb (5.85), Cd (5.63), Ni (4.62), Hg (4.52) and Cu (3.99) all showed evidence of considerable contamination; Cr (2.4) and Mn (2.22) showed moderate contaminations while Zn (0.73), Co (1.630 and Fe (0.82) implied evidence of low contamination. Overall degree of contamination (32.42) implied very high degree of contamination while Pollution Load Index (681.22) implied progressive deterioration of soils of auto-mechanic workshop clusters in the study area. It was noticed that levels Pb, Cu, Cd, Co, Cr, Ni, Mg and Hg encountered in this study showed evidence of anthropogenic input into soils of auto-mechanic workshop clusters, as against values of Zn and Fe which showed evidence of geogenic input. The progressive contamination scenario observed in soils of the auto-mechanic workshop clusters in this work were mainly attributable to anthropogenic activities arising from unprofessional ways artisans adopted in disposal of heavy metal-bearing wastes onto soils of the study area. This calls for serious concern as progressive deterioration of soil quality stands to induce negative health and environmental effects in no distant time.