Seasonal variability of soil metal contamination and risks in a Pb-Zn mining site, Southeastern Nigeria

This study investigates how seasonal variability influences soil metal contamination, spatial distribution, sources, and associated health and ecological risks in a Pb-Zn mining district of southeastern Nigeria. Using ICP-MS analysis, multivariate statistics, and geospatial mapping, we examined Cu, Zn, Ni, Mn, Co, Fe, Cd, Cr, and Pb across dry and wet seasons. Mean metal levels across both seasons followed the order: Fe˃Pb˃Mn˃Zn˃Cr˃Cu˃Ni˃Co˃Cd. Multivariate evaluations predicted anthropogenic sources for Pb, Cu, Cd, and Zn, and geogenic sources for Fe, Co, and Ni. While the mean concentrations of Ni and Co aligned with regulatory and background thresholds, those of Cu, Fe, Cd, Cr, and Pb exceeded them. Non-carcinogenic and carcinogenic health risks were recorded for Cr and Pb across both seasons and exposure groups. Geospatial mappings recorded minimal seasonal variations for Zn hotspots, but high variability for Fe. This study highlights how seasonal variations affect metal pollution patterns in areas affected by artisanal mining. The findings help improve risk assessments, support efforts to protect public health, and guide policies that promote safer and more sustainable mining practices globally.