P. J. Depetris is a senior researcher at Argentina’s National Council for Scientific and Technical Research (CONICET) and, concurrently, Emeritus Professor at Córdoba National University (Argentina). He has focused on surface geochemistry and his recent work has included the study of Patagonia’s rivers as sources of material transported to the southern coastal ocean, and other hydrological and climatic aspects in southern South America.A.I. Pasquini is Assistant Professor at Córdoba National University and a researcher in Argentina’s CONICET. Her recent work has been devoted to the study of natural and anthropogenic riverine geochemical processes; hydrological dynamics have also been thoroughly explored, in particular the impact of ENSO on South American freshwater systems.K.L. Lecomte is also an Assistant Professor at Córdoba National University and a researcher in Argentina’s CONICET. Her most recent work has been oriented toward the study of freshwater geochemical processes, mostly by means of modeling techniques applied to weathering and, particularly, to extremely acid rivers impacted by former mining activities.The authors belong to the scientific staff of the Centro de Investigaciones en Ciencias de la Tierra (CICTERRA) or, in English, Research Center for the Earth Sciences, one of Argentina’s leading research centers in the geosciences, jointly managed by CONICET and the Universidad Nacional de Córdoba, in Córdoba, Argentina (http://www.cicterra-conicet.gov.ar/).