Yalgado Zakaria Sawadogo¹, Telado Luc Bambara^{1, 2,}, Inoussa Zongo^{1, 3}, Karim Kaboré^{1, 4}, François Zougmoré¹

Mining is considered to be one of the most important sources of environmental pollution when it comes to heavy metals. Mining causes the release of large quantities of mercury, arsenic and other elements into the environment and naturally poses a serious threat to the environment. The objective of this study is to assess heavy metal contamination and the ecological risks of agricultural soils around a gold mine, mainly in Bissa, a village in the commune of SABCÉ. Twelve (12) soils samples were collected on the surface, in depths of 0 to 15cm. Seven heavy metals (Cr, Ni, Cu, Zn, As, Hg and Pb) were analyzed by atomic absorption spectrometry. From the concentrations of these metals and on the basis of the geochemical background described by Wedepohl and Turekian (1961); the geo-accumulation index (Igeo), the degree of contamination (DC), the pollution load index (PLI), the risk factor (RF) and the potential ecological risk index (RI) were evaluated. The results revealed that the average concentrations of metals obtained were classified in descending order Cr>Zn>Cu>As>Ni>Pb>Hg with the respective values 102.3mg/kg, 58.513mg/kg, 57.133mg/kg, 49.73mg/kg, 38.873mg/kg, 17.943mg/kg and 3.83mg/kg. Mean concentrations of Cr, Cu, As and Hg exceeded their respective geochemical background values, and only arsenic was above the WHO/FAO standard. The geo-accumulation index showed that 75% of the soil samples were heavily polluted with mercury (Hg). The potential ecological risk index showed that 75% of the soil samples presented a considerable ecological risk, and 8.33% presented a very high ecological risk.

soil, heavy metals, pollution, ecological risk, gold mine