Heavy-Metal Contamination and Depth-Wise Distribution in Industrial and Auto-Mechanic Workshop Soils in Anwai, Delta State, Nigeria
DOI:
https://doi.org/10.33003/fjs-2026-1022-6090Keywords:
Heavy metal contamination, Auto-mechanic workshop, Depth-wise distribution, Asaba, Soil pollution, Contamiination factorAbstract
One of the most significant, unregulated sources of soil heavy metal pollution in developing areas is from the disposal of industrial and automotive workshop waste. Moreover, there is limited baseline information for many hotspots in Nigeria. This study evaluated the levels of copper, chromium, cadmium, lead and zinc, along with pH and electrical conductivity, in soils of three industrial / auto-mechanic workshop sites (A, B, C) and one control site (D) in Anwai, Delta State, Nigeria. It employed three independent composites per site and depth (0-30, 30-60cm). Soil pH values ranged from 6.67–8.24. The levels of the five metals were significantly elevated at industrial sites as compared to control (p < 0.001). Two-way ANOVA showed significant side effects for all metals and higher subsoil than topsoil concentrations of copper, chromium, cadmium and lead, whereas zinc showed no overall depth effect. Contamination factors relative to the control ranked cadmium (6.9–10.2, very high) above zinc and copper (about 5, considerable), lead (3.4–4.0) and chromium (2.4–3.1). At all the industrial sites, cadmium, lead and copper exceeded the Nigerian DPR (EGASPIN) soil target values, while chromium and zinc did not exceed the intervention values. The higher subsoil concentrations indicate possible vertical redistribution, which requires confirmation with groundwater and geochemical data. These results suggested site-specific, metal-specific contamination from industrial sources, notably, from cadmium. Therefore, regular soil and groundwater monitoring, analytical validation with certified reference materials, and more rigorous waste-disposal regulation are required in the Anwai area of Asaba.
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Copyright (c) 2026 Uduenevwo Francis Evuen, Augustine Chukwunedum Ogonegbu, Abigail Okezi Isoje, Emmanuel Oghenetega Okorodudu, Edith Chinyere Unoka, Oghenetega Efetobo, Eunice Amarachi Dibor
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