Diffuse contamination of surface and ground waters resulting from the green revolution since 1950’s represents a major threat to the long-term sustainability of water resources worldwide. Nutrients budgets, calculated in a wide array of river basins, have shown that a high amount of nutrients can be retained or lost within the watershed, where site-specific characteristics contribute to define their fate. In the Lombardy plain (North Italy) the uneven distribution of nitrates in groundwater, not fully matched to any of the civil, industrial and agricultural sources, suggests that local features and processes (e.g. depth of water table, land use, denitrification etc.) play a key role in preserving or removing nutrients.
In this framework, the INTEGRON project, funded by the CARIPLO Foundation (Grant number: 2015-0263), aims at evaluating the role of groundwater as a temporary or permanent sink or as a source in nutrient mass balances at the catchment scale in two key sub-basins of Po River, the Adda and the Ticino.
An innovative and integrated approach is proposed, considering both surface and groundwater, combining hydrogeology and biogeochemistry and targeting both N and P species. This includes: (i) the calculation of the nutrient surplus and the load exported by rivers at the closing section to quantify the amount retained within the basin; (ii) the groundwater dating to infer the residence time of nutrients; (iii) the estimate of the amount of nutrients exchanged between surface and ground waters and the identification of processes occurring at the interface; (iv) the investigation of the factors promoting the retention or removal of nutrients (e.g. denitrification, P adsorption); (v) a socio- hydrogeological analysis to identify key-actors in the implementation of new management practices.