Assessment of Heavy Metal Contamination from Auto Mechanic Workshops in Abuja, Nigeria

Abstract

Abstract

This study investigated the effects of auto mechanic workshop activities on soil quality within three municipal area councils of Abuja, Federal Capital Territory (FCT), Nigeria — namely, Abuja Municipal Area Council (AMAC), Gwagwalada, and Kuje. The research aimed to assess the extent of heavy metal contamination and determine its impact on soil physicochemical properties and vegetation health. Soil samples were collected from fifteen selected mechanic workshops and nearby agricultural lands serving as control sites at depths of 0–10 cm and 10–30 cm. Laboratory analyses were conducted using Atomic Absorption Spectrophotometry (AAS) for heavy metals and core-cutter methods for bulk density. Parameters such as pH, nitrogen, carbon, and cation exchange capacity (CEC) were measured. Results revealed that workshop soils exhibited significantly higher concentrations of heavy metals—particularly zinc (152.22 ± 46.08 mg/kg), lead, and cadmium—compared to the control sites (0.55 ± 0.13 mg/kg). The mechanic workshop soils also showed increased bulk density, reduced porosity, and altered pH values. The Pollution Load Index (PLI) of 5.02 and Contamination Factor (Cf) of 5.0 confirmed considerable pollution levels, while vegetation cover was drastically reduced. These findings demonstrate that mechanic activities degrade soil quality and pose ecological risks. It is recommended that designated zones be established for automobile repair operations, with strict environmental monitoring and eco-friendly waste management practices.