Analysis of arsenic pollution in groundwater aquifers by X-ray fluorescence

The serious contamination of groundwater in the southeastern plain of the p rovince of Cordoba (Argentina), a phenomenon mentioned in the literature fo r over 80 years, has given rise to this initial hydrologic study covering a n area over 250 km(2). This study analyzes a rural area near a little town called La Francia, and is motivated by the existence of an important pollut ion with arsenic in the first-aquifer groundwater of the region. This pheno menon has been mentioned for a long time and evidenced by the high incidenc e of diseases associated with this element in the local population. By mean s of the X-ray fluorescence (XRF) technique, and using an energy-dispersive spectrometer, 50 samples of groundwater of the rural zone of La Francia fr om about 100m deep (second aquifer), were analyzed. The samples were excite d with a 3 kW X-ray tube and measured using a reflecting geometry with 45 d egrees of incident and take-off directions. Preconcentration techniques for the preparation of the samples were employed in order to obtain an adequat e signal-to-noise ratio. The As concentration in water was obtained using c alibration curves and the internal standard method for quantification. A hi gh percentage of the analyzed samples showed concentrations lesser than or equal to 0.05 mgl(-1). This value corresponds to the maximum pollutant leve l for humans. The maximum measured value reaches 3mgl(-1) in samples collec ted in perforations of first-aquifer wells and in some second-aquifer isola ted wells. (C) 2001 Elsevier Science Ltd. All rights reserved.