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

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 mu g/g, 8.82 mu g/g, 0.04 mu g/g, 0.006 mu g/g, and 0.048 mu g/g, respectively while in Ijero area, the mean concentration of Tl in tailings, rocks, groundwater, surface water and minewater are 9.78 mu g/g; 18.99 mu g/g; 0.004 mu g/g; 0.003 mu g/g and 0.03 mu g/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.