Assessment of aquifer contamination from on-site sanitation systems and effluent reuse in the North of Mendoza province

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 Tunuyan rivers, two large hydro-geological units developed from Quaternary sedimentation: unconfined aquifers (area of alluvial cones) and upper water-table and underlying semi-confined 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.