Multi-isotopic regional-scale screening on drinking groundwater in Lombardy Region (Italy)

Groundwater represents the main and safest source of water that supply, for drinking purposes, numerous urban and rural communities all over the world. A deep knowledge of aquifer systems in terms of quality, vulnerability and renewability is fundamental to preserve groundwater resources. Thanks to the contribution of different members of Water Alliance in synergy with Sapienza University, during November 2019 a multi-isotopic analysis at regional scale on groundwater tapped for drinking purposes in a wide area of Lombardy Region, has been carried out. The study aimed to improve knowledge about recharge mechanisms, groundwater relative age and impact of human activities on groundwater quality Each Water Alliance supplier selected wells and springs for a total of 121 samples, catching different aquifer groups and distributed from North to South. Groundwater stable isotope analyses were performed on all the monitoring points, instead tritium, nitrogen isotopes (15N and 18O in nitrates), sulphate isotopes (34S and18O) and 13C isotope in Dissolved Inorganic Carbon (DIC), were analysed in selected monitoring wells basing on previous data and major ions concentrations results. Therefore, results confirmed the key role of multi-isotopic approach in defining aquifer recharge processes, relative groundwater age and origin of pollutants, offering a useful tool to point out local issues which can be deeply investigated by each water supplier.