Fil: Bia, Gonzalo Luis.Consejo Nacional de Investigaciones Científicas y Técnicas. Centro de Investigaciones en Ciencias de la Tierra; Argentina. ; Fil: Bia, Gonzalo Luis. Universidad Nacional de Córdoba; Argentina. ; Fil: Borgnino, Laura. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro de Investigaciones en Ciencias de la Tierra; Argentina. ; Fil: Borgnino, Laura. Universidad Nacional de Córdoba; Argentina. ; Fil: Gaiero, Diego M. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro de Investigaciones en Ciencias de la Tierra; Argentina. ; Fil: Gaiero, Diego M. Universidad Nacional de Córdoba; Argentina. ; Fil: García, Maria Gabriela. Universidad Nacional de Córdoba; Argentina. ; Fil: García, Maria Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro de Investigaciones en Ciencias de la Tierra; Argentina. ; The sources and dynamics of arsenic in fresh volcanic ashes collected during the eruptions of Hudson (1991) and Puyehue (2011) volcanos, have been studied. The chemical and mineralogical compositions of both volcanic ashes were analyzed by ICP/OES, XRD, and SEM-EDS. Batch experiments were conducted to evaluate the kinetics of the arsenic release under variable pH. Results indicate that the release is enhanced under both, acidic and alkaline conditions. Besides, the positive significant linear trend found between Fe and As concentrations in the leachates suggests that arsenopyrite or/and its alteration product scorodite is one important As-bearing phase present in the ash samples. This phase would be the main responsible of the As release under acidic conditions. At higher pH, two other mechanisms are involved: desorption from Fe(hydr)oxide coatings (at neutral to slightly alkaline conditions) and dissolution of both arsenopyrite and volcanic glass at pH higher than 9. ; Fil: Bia, Gonzalo Luis.Consejo Nacional de Investigaciones Científicas y Técnicas. Centro de Investigaciones en Ciencias de la Tierra; Argentina. ; Fil: Bia, Gonzalo Luis. Universidad ...