Origin of Arsenic in Surface Water in the Southern Extreme of the Chaco-Pampean Region, Argentina. Facts and Speculations

A. FERNÁNDEZ CIRELLI; M. PUNTORIERO; A. VOLPEDO

Florencia

Congreso; 11th International Conference on Biogeochemistry of Trace Elements (ICOBTE); 2011

ISTEB

The Chaco-Pampa Plain of central Argentina is one of the largest regions of high arsenic groundwater known. Studies of As occurrence in surface water are scarce. High values were determined in two hydrographic regions in the southern extreme of the Chaco-Pampean region: SW Endorheic Basin (ESO) and Bahía Blanca (BB). Surface and groundwater of these two areas were evaluated for As, F and V content. A significant correlation was found between As and F, both in surface and groundwater, while As and V, only showed a significant correlation in groundwater. The principal geochemical processes determining the chemical composition of surface waters were analyzed through ionic relations. A cation exchange reaction between calcium and sodium takes place in the hydrochemical evolution of groundwater through Pampean loessic sediments, with groundwater being one of the sources of surface water. Therefore, the occurrence of As and related elements in surface water may be explained by its relation with groundwater.