Index of heavy metal pollution and health risk assessment with respect to artisanal gold mining operations in Ibodi-Ijesa, Southwest Nigeria

Background

Artisanal gold mining can help reduce poverty while creating job possibilities for many low-income and unskilled workers. However, it is an activity with several detrimental societal consequences. Miners are exposed to chemical toxins that have long-term health consequences.

Objectives

This study examined soil degradation, pollution, and environmental hazards from artisanal gold mining in Ibodi-Ijesa, Osun State, Nigeria. The aim is to assess the levels of Cu, Co, Cd, Pb, As, and Ni in the study area as potential indicators of environmental concerns.

Methods

Soil samples were systematically collected from 66 distinct locations surrounding the gold mining site, at depths ranging from 0 to 15 cm, within distances of 0 to 500 m, and at intervals of 100 m. These samples underwent standard laboratory procedures for heavy metal analysis using Atomic Absorption Spectroscopy (AAS).

Results: The findings showed that copper (Cu), cobalt (Co), lead (Pb), and nickel (Ni) concentrations ranged from 80.17 to 100.11 mg.kg⁻¹, 42.11 to 50.07 mg.kg⁻¹, 30.93 to 54.00 mg.kg⁻¹, and 35.30 to 44.20 mg.kg⁻¹, respectively. Nickel (Ni), cadmium (Cd), and arsenic (As) were all below the detection limit. Although all analysed heavy metal concentrations were lower than the control samples, they outperformed the control values. The contamination index showed no distinct distribution pattern, but all values surpassed those of the control samples. Furthermore, the Health Risk Index was greater than one, indicating possible health hazards for inhabitants.

Conclusion

The study indicated that artisanal gold mining operations in Ibodi-Ijesa substantially influenced soil quality, raising heavy metal concentrations and posing health hazards to adjacent populations.