Contamination status and potential ecological risk assessment of soil heavy metals at central magazine, Wa, North-Western Ghana

The growing environmental concern due to anthropogenic activities at Central Magazine, Wa (WM), makes it a potential hotspot for soil heavy metal (HM) contamination and associated health risks to nearby workers and residents. Given the lack of documentation in the area, this study aimed to assess soil HM contamination levels in soils resulting from vehicle servicing activities at Central Magazine, Wa, integrating contamination indices, ecological risk evaluation, and physicochemical characterisation to provide a more holistic environmental risk profile. Thirty-one soil samples were collected and grouped into three composites based on workshop operational characteristics: auto BAG (12), auto SET (14), and auto LEG (5). A control sample (WM-BSS) was also included. EDXRF was used to determine HM concentrations. The mean cumulative HM loads (mg/kg) were highest in WM-BAG (49,489.00), followed by WM-LEG (44,907.50), WM-SET (41,801.66), and WM-BSS (25,646.69). Contamination was assessed using enrichment factor (EF), contamination factor (CF), contamination load index (CLI), geo-accumulation index (I_-geo), and ecological risk indices. Concentrations across the operational sites exceeded those at the control site, indicating significant anthropogenic influence. Positive I_-geo values and EF > 1.5 for Pb, Zn, Cu, and Mn confirmed substantial anthropogenic contamination, while consistently elevated CLI values (1.35-1.57) across all sites indicated a progressive deterioration in soil quality. Only WM-BAG soil showed high ecological risk due to elevated Pb levels, while WM-SET and WM-LEG soils posed low risk. This study provides essential data for ecological risk assessment and supports policy formulation for sustainable waste and soil contamination management in auto-industrial zones.