Arsenic in Latin America: Part I

Abstract

A complete analysis on the occurrence of arsenic (As) in aquifers and several superficial water bodies in Latin America is presented, identified in 13 countries. The Chaco-Pampean plain in Argentina is the largest area affected by As contamination of groundwater. Research on the chemical and hydrogeological processes of release and mobilization of As has also been developed in Mexico, Chile, Bolivia, Peru and Nicaragua. In most of the contaminated areas, As originates from geogenic sources, mainly volcanic rocks, hydrothermal fluids and As-bearing minerals. However, anthropogenic sources are also present in certain zones, most of them coming from mining operations and, in some cases, related to agriculture. Mining is indeed the main As source in Brazil. The physicochemical characteristics of the water, such as pH and Eh, and presence of other ions, influence the mobilization of As. Hydrogeological conditions also determine the occurrence of As contamination. It has been found that the element is in the As(V) form in most locations. In all Latin American countries, more research has still to be conducted to determine As concentrations and speciation in water bodies used as drinking water source, to unravel its origin and mobilization processes.