Assessing Heavy Metal Accumulation Trends and Possible Sources in Soils Around Mechanic Village, Tombia, Bayelsa State, Nigeria

The present study assessed the concentration, inter-elemental relationships, and contamination status of selected heavy metals (Pb, Fe, Cd, Cr, and Mn) in surface soils collected from the Central Mechanic Village, Tombia, Yenagoa, Bayelsa State, Nigeria. Soil samples were analysed using standard procedures, and results were compared with the World Health Organization (WHO) guideline limits for heavy metals in soils. The mean concentrations (ppm) followed the order Fe (111.65 ± 26.53) > Pb (3.33 ± 1.99) > Mn (1.75 ± 0.26) > Cr (0.81 ± 0.13) > Cd (0.26 ± 0.03). All recorded values were below the WHO permissible limits, indicating an absence of acute contamination. However, the persistence and bioaccumulative potential of Pb and Cd suggest possible long-term ecological risks. Pearson correlation analysis revealed a near-perfect positive relationship between Fe and Cd (r = 0.999) and strong associations of Fe–Cr (r = 0.91) and Cd–Cr (r = 0.89), suggesting a common anthropogenic origin likely linked to mechanical activities, metal scraps, and waste lubricants. Conversely, a very strong negative correlation between Pb and Mn (r = − 0.97) indicates contrasting geochemical pathways and sources, with Pb largely anthropogenic and Mn predominantly lithogenic. The relatively low metal concentrations compared with other Nigerian mechanic environments may be attributed to the site’s shorter operational history and hydrological dilution in the Niger Delta setting. Although current contamination levels are minimal, the cumulative nature of heavy metals necessitates periodic monitoring and implementation of soil management strategies to prevent progressive accumulation and potential ecological degradation.