water Article Assessing Natural Background Levels in the Groundwater Bodies of the Apulia Region (Southern Italy) Rita Masciale 1 , Stefano Amalfitano 2 , Eleonora Frollini 2 , Stefano Ghergo 2, Marco Melita 2 , Daniele Parrone 2,* , Elisabetta Preziosi 2 , Michele Vurro 1, Annamaria Zoppini 2 and Giuseppe Passarella 1 1 Water Research Institute, National Research Council (IRSA-CNR), 70132 Bari, Italy;
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[email protected] Abstract: Defining natural background levels (NBL) of geochemical parameters in groundwater is a key element for establishing threshold values and assessing the environmental state of groundwater bodies (GWBs). In the Apulia region (Italy), carbonate sequences and clastic sediments host the 29 regional GWBs. In this study, we applied the Italian guidelines for the assessment of the NBLs, implementing the EU Water Framework Directive, in a south-European region characterized by the typical Mediterranean climatic and hydrologic features. Inorganic compounds were analyzed at GWB scale using groundwater quality data measured half-yearly from 1995 to 2018 in the regional groundwater monitoring network (341 wells and 20 springs). Nitrates, chloride, sulfate, boron, iron, manganese and sporadically fluorides, boron, selenium, arsenic, exceed the national standards, likely Citation: Masciale, R.; Amalfitano, S.; due to salt contamination along the coast, agricultural practices or natural reasons.