Water Air Soil Pollut (2015) 226: 302 DOI 10.1007/s11270-015-2558-4 Arsenic in African Waters: A Review Dompé Ghislain Ahoulé & Franck Lalanne & Julie Mendret & Stephan Brosillon & Amadou Hama Maïga Received: 10 April 2015 /Accepted: 27 July 2015 /Published online: 16 August 2015 # Springer International Publishing Switzerland 2015 Abstract The review of studies on arsenic in African waters. Few studies in Africa make the link between waters shows that arsenic can be found in high concen- human health problems and high levels of arsenic in trations in both surface water and groundwater. Arsenic water. Only two articles were found dealing with arsenic concentrations in African groundwater range between remediation. This shows that arsenic, which constitutes 0.02 and 1760 μgL−1, whilst the level of arsenic in a major public health issue in the world, has less interest surface water is ranged up to 10,000 μgL−1.Thishigh in Africa although high concentrations of arsenic have level of arsenic in surface water is related to mining been found in both surface water and groundwater in operations, agricultural drains, local sediments, dispos- some African countries. Most of the studies carried out al, and incineration of municipal and industrial wastes. on arsenic issues in Africa are dedicated to the charac- However, mining activities remain the main source of terization and the quantification of the pollution, but surface water pollution. They have thereby a strong studies on the risk to human health and treatment sys- impact on the concentration of arsenic in the environ- tems are limited. The arsenic issue in Africa needs ment. As for groundwater, high levels of arsenic occur special attention in order to avoid the problems experi- in natural conditions. It is due to the presence of iron enced in some areas mainly in Asia. oxides; sulphide minerals such as pyrite, arsenopyrite, and chalcopyrite; volcanic rocks; and geothermal Keywords Arsenic . Groundwater. Surface water. Africa D. G. Ahoulé (*) : F. Lalanne : A. H. Maïga Laboratory, Water, Depollution, Ecosystem and Health, International Institute for Water and Environmental Engineering, Rue de la Science 01, BP 594 Ouagadougou 01, Burkina Faso 1 Introduction e-mail: [email protected] F. Lalanne Arsenic is a ubiquitous element that can be found in e-mail: [email protected] rocks, water, air, animals, and plants. It is a metalloid A. H. Maïga which can have both inorganic and organic forms e-mail: [email protected] (Matschullat 2000). Arsenic species can be converted into different forms or transformed into insoluble com- J. Mendret : S. Brosillon European Membrane Institute, University of Montpellier 2, Place pounds in combination with other elements, such as iron Eugéne bataillon, 34095 Montpellier, Cedex 05, France and sulphur (Mandal and Suzuki 2002). Most arsenic J. Mendret compounds are odorless and tasteless and readily dis- e-mail: [email protected] solved in water, which creates an elevated health risk S. Brosillon (Wang and Mulligan 2006). Long-term exposure to e-mail: [email protected] inorganic arsenic may cause a wide range of health 302 Page 2 of 13 Water Air Soil Pollut (2015) 226: 302 effects, including skin lesions such as hyperkeratosis of arsenic in water greater than 10 μgL−1 will be and pigmentation changes and blackfoot disease, circu- considered high. latory disorders, diabetes and cancers of the bladder, lung, kidney, and liver (Smith et al. 1992; Gbaruko et al. 2010). In 1993, the World Health Organization 2 Arsenic Distribution in Water in Africa (WHO) reduced provisionally the guideline value from 50 to 10 μgL−1. Above this value, the water is consid- Generally, arsenic in Africa is found in a low concen- ered unfit for human consumption. Due to its high tration in natural water. Occurrence of arsenic in natural toxicity and widespread occurrence in the environment, water is dependent on the local geology, hydrogeology, several studies concerning source, behavior, and distri- and geochemical characteristics of the aquifer and cli- bution of arsenic in the environment as well as its matic factors as well as human activities. Arsenic con- removal technique were performed in the world. These centrations above WHO guidelines for drinking water studies have shown high levels of arsenic in water in have been recorded in different African countries many areas like parts of USA, China, Chile, Bangla- (Fig. 1). This figure shows for the first time, to our desh, Taiwan, Mexico, Argentina, Poland, Canada, knowledge, the distribution of arsenic in African waters Hungary, Japan, Ghana, and India (Amasa 1975; Chen and brings out the issue of arsenic in the African conti- et al. 1994;Karim2000; Chakraborti et al. 2002;Ning nent. The details of values of arsenic concentration in 2002; Smedley and Kinniburgh 2002; Wang and Mulli- the contaminated countries are reported in Table 1. gan 2006; He and Charlet 2013). These high levels of arsenic result from both natural and anthropogenic oc- 2.1 Arsenic in Surface Water currences (Mandal and Suzuki 2002; Smedley and Kinniburgh 2002; Nriagu et al. 2007). The anthropo- The concentration of arsenic in natural African surface genic sources are constituted mainly by mining activi- water is very different depending on the country, and ties, fossil fuel processing, and incineration of municipal even in the same country, it depends on the area. Low and industrial wastes. As for natural sources, arsenic is concentrations of arsenic have been noticed in some areas present in sulphide ores associated with other metals like of Tanzania, Botswana, and Burkina Faso (Taylor et al. copper, lead, silver, and gold. Arsenic can be released 2005; Huntsman-Mapila et al. 2006; Ouédraogo and from these natural sources by the combined effects of Amyot 2013) whereas high concentrations were recorded mineral weathering and high-evaporation rates. It can in Ethiopia, Ghana, Morocco, other areas of Tanzania, also come from desorption of mineral oxides and reduc- Togo, and Zimbabwe (Bowell et al. 1995; Jonnalagadda tive dissolution of iron and manganese oxides in reduc- and Nenzou 1996; El Hachimi et al. 2005;Serfor-Armah ing conditions. Although all these environmental et al. 2006; Rango et al. 2010; Rezaie-Boroon et al. conditions can be found in African countries, and 2011). For example, Rango et al. (2013) indicated that that Africa harbors the world’s largest mineral there was 566 μgL−1 of arsenic in the surface water in the reserves of gold and other minerals (platinum, Rift Valley in Ethiopia. Whilst Serfor-Armah et al. (2006) diamonds, chromite, manganese, and vanadium) have reported a range of concentrations from 150 to (Economic Commission for Africa ECA 2009), 8250 μgL−1 in the surface waters in Prestea in Ghana. the existing review articles speak very little of These high levels of arsenic in the surface water are arsenic in Africa. It may be because arsenic was usually related to the mining operation (Amasa 1975; not found in a large scale in African countries or Jonnalagadda and Nenzou 1996;Serfor-Armahetal. there are very few studies on arsenic in Africa. 2006; Kusimi and Kusimi 2012). Indeed, areas devoid The aim of this paper is to build a map of arsenic of mining activities like Okavango Delta (Huntsman- distribution in African waters using existing data Mapila et al. 2006) have generally low values of andtohighlightthelackofdatacomparingtothe arsenic in the surface water, whereas in mining activity probable magnitude of the problem. It is also areas the surface waters have high levels of arsenic. important to show what the arsenic threat repre- However, Rango et al. (2010)havefoundhighlevels sents for human health in Africa and to provide an of arsenic in the surface water in the Rift Valley which overview of the methods studied to remove arsenic is devoid of mining activities. According to them, local from water in Africa. In this document, all values sediments were the main source of arsenic in water in Water Air Soil Pollut (2015) 226: 302 Page 3 of 13 302 Fig. 1 Distribution of arsenic in African waters the Ethiopian Rift Valley. Rezaie-Boroon et al. (2011) 2008 from Malawi). However, the values quoted in the have also highlighted high concentrations African literature show a very large range from 0.02 to (6460 μgL−1) of arsenic in the surface water in the 1760 μgL−1 (Table 1). In contrast to surface waters, the vicinity of Lomé and other big cities. This high con- origin of the high levels of arsenic in groundwater is centration of arsenic was due to the impact of the mainly natural. So, the high concentrations of arsenic effluents from the industrial activity as well as hazard- reported in the groundwater by Smedley et al. (2007)in ous waste dumping. Surface waters have generally a Burkina Faso (1630 μgL−1) and Kusimi and Kusimi higher level of arsenate [As (V)] than arsenite [As (2012) in Ghana (1760 μgL−1) have for origin weath- (III)]. Ahmad and Carboo (2000) who worked on ered rocks of the underlying geology and are not due to speciation of As (III) and As (V) in some Ghanaian mining activities. When considering the concentrations gold tailings observed the absence of As (III) in river- of arsenic in surface waters (0.5 to 73 μgL−1)andin bed sediments. This low value of As (III) in surface groundwaters (<0.1 to 4 μgL−1) from Tarkwa (Asante water may be attributed to the fact that As (III) has et al. 2007), or the ones in Obuasi ranging from <2 to been oxidized to As (V) by dissolved oxygen. How- 175 μgL−1 and from <2 to 64 μgL−1,respectively,in ever, Smedley et al. (1996) found some streams which surface waters and groundwater (Smedley 1996), two have high As (III) content ([As (III)]/[Astotal]>0.5), gold mining areas in Ghana, it can be noticed that probably as a result of methylation and reduction mining activities affect less the groundwaters than sur- reactions mediated by bacteria and algae.