Assessment of Potentially Toxic Metals from Mine Tailings and Waste Rocks Around Mining Areas of Oshiri-Ishiagu Region, Southeastern Nigeria

Potentially toxic metals concentration and pollution in mining areas have become a major environmental concern. Predicting the toxic metals (Pb, Cd, Ni, Co, Zn, Mn, Fe, and Cu) in waste rocks and mine tailings in the study area is important in establishing environmental policies and potential pollution sources. The mine tailings and waste-rock samples were geochemically analyzed using Atomic Absorption Spectrophotometer to identify distribution of the potentially toxic metal concentrations (in mg/kg). Data obtained were standardized and assessed using risk factors namely; index of geoaccumulation, contamination, and enrichment factors to define parameters that caused the toxic metal partitions in mine tailings and waste rocks. Geochemical evaluation indicates the potentially toxic metals concentrations in the following trends: Mn > Zn > Cu > Pb > Co > Ni and Zn > Mn > Fe > Pb > Cu > Co for waste rocks and mine tailings, respectively. Results of the analysis show that Co, Cu, Mn, and Ni have values of the index of geoaccumulation (Igeo) ranging from unpolluted to moderate pollution levels in waste rocks and mine tailings; indicating insignificant contribution to contamination in the area. The index of geoaccumulation for Fe in mine tailings which ranges from 1.94 to 2.04 indicates moderate to strong pollution in tailings but devoid of significant pollution in waste rocks with values less than 0.14. However, Cd recorded the highest pollution level with maximum Igeo values of 6.81 in waste rocks and 3.83 in mine tailings. Meanwhile, some mine sites have values of pollution load index (PLI) less than 1; indicating areas around the mine province that are still unpolluted. Notwithstanding, enrichment in most of the environments produced conduits through which natural biospheric sources, such as air, water, and soil, could deteriorate. The outcome of this study would, therefore, establish a database for future environmental risk assessment of the region.