Identifying occurrences of groundwater arsenic in Latin America: A continent-wide problem and challenge

摘要

The first reports of arsenic(As)-rich groundwater in Latin America are those of Argentina (Goyenechea, 1917; Ayerza, 1917a,b, 1918). The discoveries of As-contaminated water resources in Chile and Mexico fall about together with the first important discovery made in Asia (Taiwan) at the beginning of the 1960s. Until today, remediation of the problem was performed only in some bigger cities. The population of rural areas and those from isolated urban areas without centralized water supply systems still suffer from ingesting As-contaminated water. In Latin America, at least more than 4 million people depend on drinking water with As concentrations exceeding the WHO limit (10 μg/L). In Argentina, around 4 million people are exposed, whereas in Bolivia, Ecuador, Colombia, El Salvador, and Guatemala where As has been detected recently in drinking water; the extent of the problem still remains poorly known. Sources of As are predominantly geogenic and due to weathering of rocks and other geological processes. Arsenic mobilization into ground- and surface water is predominantly due to sulfide oxidation in areas with sulfide mineral deposits (e.g. Andes, Central America, Mexico) and des-orption of As at high pH values under oxidizing conditions (e.g., Chaco-Pampean Plain of Argentina and Uruguay). Geothermal water mixing with freshwater resources is important in many regions of the Andes as well as the active volcanic areas of Central America and Mexico. Detailed information about As occurrence in water resources of Latin America, the related health effects and experiences on remediation are described in Bundschuh et al. (2008,2009). In this paper, we will only give a short summary of the principal regions of Latin America where the water resources are contaminated by As.