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Groundwater contaminated with arsenic and fluoride in the Argentine pampean plain

Abstract:

The phreatic aquifer of the Los Jagueeles basin is made up principally of Quaternary loessic sediments. It has sodium bicarbonate (high and middle basin) and sodium sulfate (lower basin) water, with fluoride and arsenic concentrations that exceed the permissible limits for human consumption. The major contents of fluoride and arsenic are found in the middle basin, where the predominance of loess, bicarbonate waters, and the highest Na super(+)/Ca super(++) index values coincide. The fluoride is derived from the main components of loess, with anion exchange being the most important release mechanism. Arsenic is derived from the alteration of volcanic glass and, although it is generally related to reducing conditions, it occurs in the basin under oxidizing conditions. In this paper, some appropriate techniques to lower the concentrations of fluoride and arsenic are suggested.