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Some activities carried out in the Northern part of the province of Mendoza may affect groundwater quality: industrial effluent disposal and reuse for irrigation, fertilizer application, on-site sanitation systems, sewer leaks, etc. In this area, cut across by the Mendoza and Tunuyán rivers, two large hydro-geological units developed from Quaternary sedimentation: unconfined aquifers (area of alluvial cones) and upper water-table and underlying semiconfined and confined aquifers (where the study area is located). The objective of this paper is to identify the source of nitrate contamination in aquifers. Several physical-chemical and biological parameters were analyzed to assess groundwater quality, and isotope techniques were used to trace the origin of groundwater and the source of nitrates. Results show that nitrate contamination in semi-confined and confined aquifers does not originate in the overlying unconfined aquifer, which is affected by reuse of industrial effluents, but is caused by the horizontal groundwater flow from the greater Mendoza area contaminated by sewer leakage and on-site sanitation systems. [ABSTRACT FROM AUTHOR]

A tool for water pollution risk management is developed in this paper. It has been inspired in methods commonly used on Environmental Impact Studies, such as Importance Matrix and Risk Evaluation. The study was focus on the lower Tunuyán River irrigated zone ("oasis"), being the catchment area located on the eastern side of the Cordillera de Los Andes, Mendoza province, Argentina. The proposed method is based on the determination of the following data in each Management Unit (MU)4: 1. terrain vulnerability; 2. wastewater hazard; 3. risk categories; 4. the index priorities of risk management. For easy understanding all variables can be shown on different maps. The data generated can be analyzed from different approaches, updated through new data and knowledge of the nature of hazard (i.e.: contaminant type, discharge period, etc.) and vulnerable elements (i.e.: aquifer type, groundwater depth, strata permeability, soil quality, etc.) in relation with water pollution processes. This feature gives to this method a dynamic approach. Additionally, it is a practical tool since it allows the possibility of making a ranking of management priorities according to a gradual application of measures for water pollution risk reduction. Taking into account the worldwide glacier retreat tendency due to Global Warming and the related reduction of glacier-fed river discharges, it is essential to take water control measures as soon as possible. [ABSTRACT FROM AUTHOR]