Abstract
The arsenic speciation analysis of ground water was undertaken in southern La Pampa and Buenos Aires provinces of Argentina. These regions have been reported to have high levels of arsenic in waters resulting from the layers of volcanic ash within the Chaco-Pampean plain. Forty wells were sampled adjacent to ruta 35 between San Martin (La Pampa) and San German (Buenos Aires). A field-based method utilising solid phase extraction cartridges enabled the selective retention of iAsIII, iAsV, MAV and DMAV. All fractions and a ‘total’ arsenic AsT acidified sample were analysed by ICP-MS using a collision cell. Total arsenic levels varied from 23.0 to 289.0 μg L-1, with the highest levels in La Pampa. Urban well waters from San Martin and San German were well above the World Health Organisation (WHO) guidelines for drinking water (10 μg L-1 AsT). Speciation levels varied depending on province, type of well, conductivity and redox potential (Eh); but not pH. In this study for rural wells arsenite (iAsIII) was the predominant species, whereas for urban wells in Buenos Aires it was arsenate iAsV.