Impacts of artisanal gold mining on soil, water and plant contamination by trace elements at Komabangou, Western Niger

Abstract

Gold mining generates trace elements in the environment that are often associated with adverse effects on human health. This study determines trace elements levels in water, soil and plants (Datura inoxia and Calotropis procera) in Komabangou area, the main artisanal gold mining site in Niger. The collected samples were pretreated before trace element analysis by inductively coupled plasma mass spectrometry (ICP-MS) for soils samples and by inductively coupled plasma optical emission spectroscopy (ICP-OES) for waters and plants samples. For soils, concentrations reached up to 555 mg kg−1 and 468 mg kg−1 for As and Zn, respectively. In waters, highest levels were observed for Zn (540 mg L−1), followed in decreasing order by Cu (7.4 mg L−1) and Al (4.27 mg L−1). As and Zn concentrations were 134 mg kg−1 and 388 mg kg−1; 49 mg kg−1 and 46 mg kg−1 respectively in leaves of Datura inoxia and Calotropis procera from gold site, whereas As and Zn, represented only 0.56 mg kg−1 and 0.48 mg kg−1; 6.40 mg kg−1 and 46 mg kg−1 respectively in leaves of control species. In fact, results obtained revealed both contaminations by trace elements of soil and water for the majority of samples taken in gold zone with an exceeding of limit values recommended by WHO in particular for As, Cr, Ni, Pb and Zn. Therefore, the establishment of a monitoring and treatment program for polluted soils and waters in this gold zone would be necessary to preserve human health.