Arsenic in Africa: potential sources, spatial variability, and the state of the art for arsenic removal using locally available materials

During the past two decades, several studies on arsenic (As) occurrence in the environment, particularly in surface and groundwater systems have reported high levels of As in many African countries. Arsenic concentrations up to 10,000 μg/L have been reported in surface water systems, caused by anthropogenic activities such as mining, industrial effluents, and municipal solid waste disposals. Similarly, concentrations up to 1760 μg/L have been reported in many groundwater systems which account for approximately 60% of drinking water demand in rural Africa. Naturally, As is mobilized in groundwater systems through weathering processes and dissolution of As bearing minerals such as sulfides (pyrite, arsenopyrite, and chalcopyrite), iron oxides, other mineralized granitic and gneissic rocks, and climate change factors triggering As release in groundwater. Recently, public health studies in some African countries such as Tanzania and Ethiopia have reported high levels of As in human tissues such as toenails as well as in urine among pregnant women exposed to As contaminated groundwater, respectively. In urine, concentrations up to 150 μg/L were reported among pregnant women depending on As contaminated drinking water within Geita gold mining areas in the north-western part of Tanzania. However, the studies on As occurrence, and mobilization in African water systems, as well as related health effects are limited, due to the lack of awareness. The current study aims to gather information on the occurrence of As in different environmental compartments, its spatial variability, public health problems and the potential remediation options of As in water sources. The study also aims at creating awareness of As contamination in Africa and its removal using locally available materials.