Toxicity, uptake, potential ecological and health risks of Thallium (Tl) in environmental media around selected artisanal mining sites in Nigeria

ABSTRACT

Thallium (Tl) in environmental media poses great threat to the environment and human health. Contamination, toxicity and potential ecological and health risks of thallium associated with mining activities were studied in this paper. Results showed that the average content of Tl in tailings, rocks, groundwater, surface water and mine water in Anka area are 7.89 μg/g, 8.82 μg/g, 0.04 μg/g, 0.006 μg/g, and 0.048 μg/g, respectively while in Ijero area, the mean concentration of Tl in tailings, rocks, groundwater, surface water and minewater are 9.78 μg/g; 18.99 μg/g; 0.004 μg/g; 0.003 μg/g and 0.03 μg/g respectively. The percentage concentration of K, Ca, Na an Mg in soils of the area are 0.66, 15.37, 0.42 and 3.21 while in sediments their concentrations are 0.74, 12.61, 0.59, and 2.61. In the tailings, the percentage concentration of K, Ca, Na and Mg are 0.81, 16.68, 0.68 and 2.97 respectively. Tl concentrations from the media are mainly from artisanal mining and mineral processing of gold (Au), lead (Pb), zinc (Zn) and minerals associated with pegmatites. Single factor pollution index is greater than 1 and revealed that soils and sediments are uncontaminated by Tl while tailings and water are contaminated by it. Tl was highly available in plants of the area and the content of Tl exceeded the recommended limits. Also, the daily intake of the metal is above the recommended limit. Tl poses low to very high ecological and health risk in the area.

KEYWORDS:

• Ecological risk
• health risk
• mining
• Nigeria
• plant uptake
• Thallium

Acknowledgements

The authors are indebted to the efforts of Ma Liam and Atta Ratsool during the first author visit to the State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Science, Guiyang, China for laboratory analysis of samples. Authors appreciate the Zamfara State Ministry of Environment, the Heads of Anka, Arufu and Ijero for providing the enabling environment to carry out this research. We also appreciate the assistance of Oladoyin Ayodeji Felix and Haske Mustapha during sample collections.

Disclosure statement

The authors declare that no conflict interest exist in this study.

Additional information

Funding

This work was supported by the opening fund of the State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Science, Guiyang, China with a grant number SKLEG2017910.