Analysis of Heavy Metal Distribution in Soils Around Lead-Zinc Mining Areas in Ebonyi State, South East Nigeria

Lead-zinc mining in Ebonyi State, South East Nigeria, has intensified in recent years, raising concerns about heavy metal soil contamination in areas adjacent to ore processing sites and tailings storage facilities. This study analyses the spatial distribution of heavy metals in soils surrounding lead-zinc mining operations in the Enyigba mining district of Ebonyi State. Systematic soil sampling was conducted at four depths (0 to 10, 10 to 20, 20 to 30, and 30 to 40 centimetres) across a grid of 45 sample points. Samples were digested and analysed for lead, zinc, cadmium, and copper concentrations by flame atomic absorption spectrometry. Geostatistical interpolation was used to produce spatial distribution maps. Results reveal lead concentrations exceeding the Dutch Target and Intervention values at approximately 60 percent of sampling points in the immediate mine vicinity, with contamination decreasing logarithmically with distance. Vertical profiles show downward migration of zinc and cadmium into subsurface horizons, indicating ongoing leaching through the soil profile. The geo-accumulation index classifies the majority of near-mine soils as moderately to heavily contaminated for lead. Health risk calculations for child exposure pathways identify soil ingestion as the dominant route of concern. Recommendations include topsoil containment at processing sites and health screening for children in the three nearest communities. Keywords: heavy metals, lead-zinc mining, Ebonyi State, soil contamination, Enyigba.