Hydrogeochemical characterization of the main aquifer of the “Litorale Domizio-Agro Aversano NIPS” (Campania — southern Italy)

Abstract

The aim of the paper is the identification in a wide area located north of Napoli city (southern Italy) of different sectors and/or different sources of anthropogenic or natural contamination in groundwater, in order to guide more effective decontamination intervention and to establish long-term environmental measures. Local administrators and environmental agencies can follow the methods used for this first characterization and zonation of a wide region for planning more focused investigations.The area includes a large part of the “Litorale Domizio-Agro Aversano” NIPS, recognized by the Italian State as a National Interest Priority Site, where there is a need to implement characterization and remediation activities. In this area the main aquifer is located in the Volturno river plain; the intensive agriculture and the presence of numerous dumping sites (both legal and illegal), has produced widespread contamination, with many wells showing very high nitrate concentrations and point source pollution (heavy metals, hydrocarbons, pesticides) has also been noticed.Moreover, groundwater presents different kinds of “natural contamination” such as high fluoride concentration (almost everywhere >1.5mg/L) and high arsenic concentration in the zones related to volcanic formations and, in some sectors, high sulphates deriving from present and/or past hydrothermal conditions. Close to the rivers, lower nitrate content is related to reducing conditions. Low sulphate contents and high Fe and Mn contents corroborate the presence of a reducing zone.The groundwater quality in the plain is influenced mainly by groundwater subsurface flows from the carbonate aquifers and by the proximity of volcanic districts, as stressed also by the statistical analysis. Indeed, the zonation of hydrochemical facies on the basis of the statistical analysis indicates clearly the different processes occurring in the aquifer along the groundwater flow path (contaminated areas, areas with reducing conditions, areas with carbonate influence, etc.).The main results are in the proposition of a synergic use of different kinds of data for sustainable aquifer management. Indeed, it is possible to rehabilitate wide areas by means of education, legislation and long-term environmental measures, without recourse to expensive treatment processes.