Variability of As levels of the phreatic and thermal aquifers in the geographic space of the southern Pampean region (Argentina)
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Abstract
The semiarid area of Bahía Blanca -SW pampean region-, was recently affected by an intense drought causing an unusual lowering of water storage in Paso de Las Piedras dam (minimun: 154.1 m asl). Although the emergency state is over, population without access to tapped water utilizes the phreatic and the thermal aquiphers. In both them water quality (CAA, OMS, EPA) was evaluated determining As, F, B and V. Arsenic (18-500 µg L-1) reached maximun levels in Gral. D. Cerri and Villa Aeropuerto, associated to high F (2,500-3,500 µg L-1). In the sector of Los Chañares, urbanization without connection to public water network, salinity was high. B was <300 µg L-1 in solely 3% of the sampled waters at the NE of Bahía Blanca. V reached 50-500 µg L-1 (43% of samples), 500-1,000 µg L-1 (35%) y 1,000-2,450 µg L-1 (12%). The general trend showed increments towards the Atlantic coast and a geographic distribution of heterogeneous areas of preferential concentrations. The thermal aquifer had acceptable As, B and F for human use, a 35% of the samples had V and yielded 300-600 µg L-1 of B in some areas at the WNW.