Trace metals concentrations in the upper basin of río Luján (Buenos Aires, Argentina)

A. PÉREZ CARRERA; A. FERNÁNDEZ CIRELLI

Ciudad de Valencia, España

Congreso; International Congress As2008 “Arsenic in the Environment: from Nature to Humans”; 2008

International Society of Groundwater for Sustainable Development

Human activities are continuously modifying the quality of continental waters. Agriculture has been identified as a source of heavy metals via fertilizers, industrial effluents contain a wide variety of pollutants and metal concentrations in water may be also affected by municipal sewage effluents. The río Luján basin in the province of Buenos Aires, Argentina comprises a drainage area of 2690 km2 with a population of 1637576 inhabitants. This basin receives agricultural, industrial and domestic effluents and the lower basin is highly polluted. Few studies have been performed in the upper basin. In this study, trace metals concentration were determined in the mouth of río Luján (county of Mercedes) in order to determine the base line before the river is polluted. Trace metals (As, Cd, Cr, Pb, Zn, Ni and V) were determined in five sampling stations along the river by ICP-OES. Determinations were performed in duplicate with a relative error < 1.0% for all of them. Levels of Cd, Cr, Pb, Zn and Ni were under the detection limit of the method. This trace metals are characteristic of anthropic contamination. On the other hand, arsenic content ranged from 15 to 95 µg/L, and vanadium ranged from 113 to 190 µg/L. The presence of these two elements in high concentrations suggests relation with groundwater, since high arsenic groundwaters are characteristic of the pampean plains in Argentina. Therefore samples of shallow groundwater in the area were analyzed and arsenic concentration between 15 and 60 µg/L were determined. In all cases, arsenic concentration in water samples were higher than the upper limit recommended by local regulations for human drinking water (10 mg/L).