Effect of Lead Mining on the Physico-Chemical and Microbial Properties of the Soil in Anyiin Community, Logo Local Government Area Benue State, Nigeria

Abstract

This study evaluated the effects of lead mining on the physicochemical, biological properties and contamination status of soils in Anyiin Community, Benue State, Nigeria. Soil samples were collected at two depths (0–30 cm and 30–60 cm) and distances of 0 m, 200 m, and 400 m from the mining sites. Samples were analyzed for physicochemical, biological properties, heavy metals, hydrocarbons, nutrients, and microbial populations. Sampling depth significantly influenced soil pH, copper (Cu), mercury (Hg), nickel (Ni), and iron (Fe), while most parameters were not significantly affected. Soil pH reduced from 7.042 to 6.867 with depth, whereas Cu, Hg, Ni, and Fe increased significantly. The interaction between sampling distance and depth significantly affected soil properties. Most heavy metals decreased with increasing distance from the mining source. Arsenic declined from 13.10 mg/kg at 0 m to 7.35 mg/kg at 400 m, while manganese decreased from 272.50 to 112.80 mg/kg. Similar reductions occurred for other metals. Total petroleum hydrocarbons decreased from 271 to 162.50 mg/kg, while total organic carbon declined from 2.85% to 1.65%. Nutrients, oil and grease, electrical conductivity, hydrocarbon-utilizing bacteria, and total heterotrophic fungi generally decreased with distance. The findings establish that lead mining significantly influences soil quality, with contamination more noticeable near the mining area and spreading horizontally and vertically through the soil profile. Regular monitoring, mining-waste management, and reclamation of degraded areas are recommended to minimize soil contamination and environmental risks.