Assessment of Potentially Harmful Elements (PHEs) in Farm Soils Near Abandoned Tin–Columbite Mine Sites, Jos, Barkin Ladi, North-Central Nigeria

Abstract

An assessment of potentially harmful elements (PHEs) in farm soils around abandoned tin–columbite mine sites in Jos and Barkin Ladi, north-central Nigeria, was conducted to evaluate contamination levels and potential environmental risks. Thirty-three composite soil samples and four control samples were collected from cultivated farmlands and analyzed using Inductively Coupled Plasma–Mass Spectrometry (ICP–MS). Pollution assessment was conducted using the Index of Geo-accumulation (Igeo) and Contamination Factor (CF). The results indicate elevated concentrations of several trace elements, particularly Pb, Ba, Ce, Zn, and Mn, reflecting both lithological influence and anthropogenic contamination associated with historical mining activities. Lead concentrations exceeded background levels in all sampled soils, while silver showed localized anomalous enrichment. Geo-accumulation and contamination factor analyses revealed that most elements were in the unpolluted to moderately contaminated range, whereas Ag and Ba showed very high contamination levels. Chromium and nickel largely reflected geogenic contributions from the parent rocks. The study demonstrates that abandoned mining activities continue to influence the geochemical quality of agricultural soils within the study area. The enrichment of toxic elements such as Pb, Ba, As, and Ag raises concerns regarding long-term soil quality, crop contamination, and human exposure through the food chain. Continuous environmental monitoring, improved irrigation management, and remediation of contaminated mine sites are therefore recommended to support sustainable agriculture and protect public health.