In the absence of industrial pollution, the presence of As, Mo, V and U in Chasicó Lake cannot be attributed to anthropic sources. Alternatively, these trace elements originate from volcanic glass from Pampean loess (Teruggi, 1957). Weathering of sediments of Chasicó Lake and the evaporation–crystallization process could be one of the factors controlling the chemical composition of the water of the Lake (Puntoriero et al., 2014b). Further studies are required in order to analyze the geochemical processes determining the chemical composition of the Chasicó Lake