First evaluation of water stable isotopes data for the groundwater bodies in Campania

The oxygen (δ18O) and hydrogen (δ2H) isotope composition of 13 groundwater bodies at 52 monitoring sites was measured in the period 2010–2016 for investigating the recharge areas of the Campania Region Groundwater Bodies as defined by the Southern Italy District Water plan. The results were compared with rainwater reference values from literature taking also marine contamination and elevation effects into account. The groundwater stable istope data matched well with MWL reported in the most recent papers for Southern Italy. The quantitative evaluation of the samples spatial variability was performed with multivariate statistical analysis including cluster analysis. As a first result, mixing processes were detected for sites located near the sea and for hydrothermal springs. The influence of high elevation recharge areas was recognized for some monitoring points in mountain karst aquifers, whereas most of the wells in the alluvial plains showed rather constant values, probably due to the large recharge areas, smoothing local effects. The high correlation of groundwater δ18O and δ2H values versus elevation a.s.l. evidenced the prevalence of rainfall recharge for most GWB.