Pollution indices and health risk due to mercury in the Buhemba artisanal and small-scale gold mine of Tanzania

Mercury Pollution and Health Risk in Buhemba

Abstract

This study assessed mercury (Hg) contamination and associated ecological risks in soils from the Buhemba artisanal and small-scale gold mining (ASGM) area in Tanzania. Soil samples (n =40) were collected from depths of 0-20 cm and 20-40 cm and analyzed using Energy Dispersive X-Ray Fluorescence (ED-XRF) utilizing the XOPOS 4R0138 instrument. The findings revealed that the average total Hg levels in mining soil were 23.58 mg/kg at a depth of 0-20 cm and 7.30 mg/ kg at 20-40 cm—exceeding national and international limits. The contamination/pollution factor and geo-accumulation index were 78.60 and 3.97 at 0-20 cm, and 24.33 and 2.28 at 20-40 cm. Additionally, the prospective ecological risk index and risk quotient were respectively 3143.73 and 589.45 at 0 20 cm, and 973.15 and 182.47 at 20-40 cm. Hg concentrations in Buhemba ASGM soils ranged (1.23–41.25 mg/kg). Pollution indices (CF ≥16; I-geo 3–4; ER ≥320; RI ≥600; RQ ≥1) confirmed severe Hg contamination. The significant difference of (p < 0.05) was revealed between soil depths and a positive relationship between Hg level and risk indices. These results suggest that ASGM activities are the primary source of pollution. On the other hand, analytical limitations and the use of international background values may lead to uncertainties. This work highlights considerable potential human health and ecological risks, underscoring the need for remediation plans and reinforced environmental management. Carrying out Hg remediation plans and soil improvement technologies are immediately needed. Community-based interventions and strengthened regulatory oversight are also recommended.