CONICET | Buscador de Institutos y Recursos Humanos

In this study, chemical and isotopic techniques were used to the elucidation of the possible origin of the salinization of waters and soils in an area located in the SO of the Comodoro Rivadavia city, Chubut, where a forest receives irrigation reused water from domestic effluents. It is also boundary by zones of petroleum activities located in the West. Samples from superficial channels (M1 a M6) and phreathic samples (F1 a F3) were taken. In addition, soil samples surrounding these sites were analyzed. X Ray Diffraction Analysis (XRDA) and Scanning Electron Microscope (SEM) revealed the major presence of sodium salts (thenardite). Waters were classified in two groups: sodium bicarbonate (M3, M5, M6 and F3) and the rest are sodium sulfate chloride. Sodium is the dominant cation in the 100% of the samples and sulfate is the dominant anion in the 67% of the cases. The isotopic composition (2H y 18O) of the samples M3, M5, M6 and F3 are similar to aqueduct water. M1 and M2 are depleted and they can, probably be, a mixture between rain/snow and groundwater provide by the lower aquitard or local flow or a mixture with waters from petroleum industry. M4 is the most enriched and it could probably be related with regional flow and saline lakes associated. F1 and F2 are the most depleted and their values are related to groundwater from Chenque Formation. Finally, it was performed a statistical Principal Component Analyzes (PCA). A new record of isotopic composition including surface waters and groundwater will allow corroborating dilution mechanisms from marine soils, evaporation processes and anthropical influence. In addition new determinations like strontium and radium isotopes will allow supporting salinization mechanisms.