Using Chemical Modeling to Asses Water Quality in the Raigón Aquifer System in Southern Uruguay

Julia Torres^1, , Lorena Gonzatto¹, César Goso², José Luis Fernández-Turiel³, Marta Rejas³, Maite García-Vallés⁴, Carlos Kremer¹ and Eduardo Kremer¹

¹Cátedra de Química Inorgánica, DEC, Facultad de Química, Montevideo, Uruguay

²Instituto de Ciencias Geológicas, Facultad de Ciencias, Montevideo, Uruguay

³Instituto de Ciencias de la Tierra Jaume Almera, labGEOTOP, CSIC, Barcelona, España

⁴Facultat de Geologia, Universitat de Barcelona

Cite this paper:
Julia Torres, Lorena Gonzatto, César Goso, José Luis Fernández-Turiel, Marta Rejas, Maite García-Vallés, Carlos Kremer and Eduardo Kremer. Using Chemical Modeling to Asses Water Quality in the Raigón Aquifer System in Southern Uruguay. Journal of Environment Pollution and Human Health. 2015; 3(2):31-38. doi: 10.12691/jephh-3-2-2

Abstract

The Raigón aquifer is an important groundwater system in southern Uruguay. The increasing use of groundwater resources in the last decades has provoked changes in the concentration of many elements which are strongly related to anthropogenic pollution sources. Concentration levels are useful to detect changes in reservoir status but it is also necessary to analyze their chemical significance in order to make an accurate assessment of the sources of contamination and the causes of changes. In this work we use the available thermodynamic data to calculate chemical speciation on these groundwater samples. Trace elements present as anions, in particular Se and Mo, are especially focused to show the chemical modeling possibilities. Both elements form anionic species, predominantly MoO₄^2- and SeO₄^2-. Results show that these anions interact in solution and are greatly influenced by the concentration of the abundant calcium ion. Localized changes in pH can strongly affect the situation. The same is observed with the pE parameter, but only in the case of Se. Chemical speciation of trace elements is in general highly dependent on pH, pE and concentration of major elements. In consequence, for a fixed analytical total concentration, these parameters can markedly change the situation, affecting the mobility, the bioavailability and environmental fate of these elements. The strategy employed in this work can also be extended to the study of many other environmental water scenarios.

Keywords:
Raigón aquifer system groundwater chemical modeling speciation trace elements

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