Source and Speciation of Arsenic in the Groundwater of the Paleoproterozoic Basement of Burkina Faso

Arsenic in drinking water causes serious health problems in many regions of the world, and Burkina Faso is not an exception. In Burkina Faso, few studies have examined the speciation of arsenic and identified its source. However, health problems linked to its presence in drinking water are evident in several regions of the country. The purpose of this study is to identify the origin and forms of arsenic in groundwater from the Paleoproterozoic basement of Burkina Faso. To this end, arsenic-contaminated water samples from boreholes in the Yadga, Oubri, and Nakambé regions were analyzed. Geological sections showed that the boreholes were drilled into shales and granitoids. The highest As concentration (98.7 μg/L) was found in the Yatenga volcanic-sedimentary shales in Ouahigouya. The results of the physicochemical parameter analyses showed that the analyzed waters are consistent with those of the basement, and the very strong correlation between conductivity and bicarbonates (0.98) reflects their natural mineralization. The strong correlations between electrical conductivity, ${\text{HCO}}_3^{？}$ , Ca²⁺, Mg²⁺, Na⁺, and As along the F1 axis indicate that the As originates from the aquifer, while the correlation between As and ${\text{SO}}_4^{2？}$ axis indicates that the arsenic originates from sulfide minerals in the mineralized basement. Furthermore, the speciation of arsenic shows that As(III) is the predominant form. Since this form is the most toxic, it exposes populations to serious health conditions such as hemolysis and kidney problems.