THE LATIN AMERICAN ARSENIC PROBLEM: EXPERIENCES FROM TAPPING ALTERNATIVE WATER RESOURCES FOR PROBLEM MITIGATION

The arsenic (As) problem in drinking water (coming from natural pollution) is long known in Argentina, Mexico, and Chile, and has been recently discovered in Bolivia, Colombia, Costa Rica, Cuba, Ecuador, El Salvador, Guatemala, Honduras, Nicaragua, Uruguay and Venezuela. The solution of this problem, affecting about 14 million people in Latin America (based on the 0.01 mg/L limit), is a severe challenge. In this paper, some Latin American experiences of tapping alternative water resources are discussed as options to solve the problem. A successful example can be drawn from Argentina, where water with low As concentrations is transported by a canal from Salta province to Monte Quemado (Santiago del Estero province). Same procedure is successfully applied in northern Chile to supply water (after As removal) to the city of Antofagasta. Other possible future actions can be pointed out. It is planned to transport water from the Paraná river to Ricardone (Santa Fe province) and to construct a canal or pipeline from Santiago del Estero to Santa Fe. However, long pipelines for water supply may only be a sustainable option if there is no other local water source or if their treatment is too expensive. Seawater desalination —from large high-tech desalination plants to simple but state-of-art equipments powered partly by renewable energy resources for small communities— has become nowadays an alternative source. The reverse osmosis seawater desalination plant of Antofagasta city produces 52,000 m³/day. Another example is that of Taltal where a desalination plant produces 5 l/s, covering 15% of towns water consumption. Other examples in northern Chile are the Esperanza and Escondida mines. Targeting As-safe aquifers within As affected areas is another option for tapping alternative water resources. Our actually ongoing pilot project compares two representative pilot areas in Bengal Delta (Bangladesh) and Santiago del Estero (Argentina). This approach calls for installation of safe wells, and was currently proven in Bangladesh as a sustainable mitigation option, where sediment color could be used to identify As-safe aquifer zones for installation of tube wells. Initial results from NW Argentina are difficult to interpret because the conditions and sources of As to aquifers in Argentina are very different from those in Bangladesh.