Influence of polluted surface water on the aquifers of the Salí river valley, Tucumán, Argentina

GARCÍA M. G; HIDALGO M. DEL V; BLESA M. A

Congreso; XXXII Congreso Internacional de Hidrogeología; 2002

Hydraulic connections between the Salí River and the aquifers developed in the river valley are not accurately defined. Surface water quality is strongly perturbed by a great load of organic matter and some trace metals. For that reason, surface water is not used for water supply, which is instead carried out by groundwater pumping. From chloride mass balance, it is estimated that 50% of deep groundwater chemical composition originates from river water. However, groundwater quality is not strongly affected by the river water ingress, because of the high tendency of the organic matter to decompose during infiltration and because of the precipitation and/or adsorption of Fe and Mn. The low phreatic water quality is not a direct consequence of the Salí River influence. The river contributes only in a 20% to the chemical composition and is probably partially responsible for the levels of organic matter and the lack of dissolved oxygen. The high concentrations of some trace metals (As, Fe and Mn) derive from the weathering of the minerals that compose the loess, where phreatic is enclosed