Background contaminants values in groundwater: methodological analysis in the case study of Turin plain (NW Italy)

Background Values (BVs) of diffuse pollutants in groundwater represent a very important information for the correct comprehension of contaminant phenomena and constitute an operative tool for local authorities.The aim of the study is to highlight the Background Values (BVs) differences between the use of local or regional data in the same sector in the Piedmont plain shallow aquifer considering different chemical parameters. More specifically, chlorinated solvents and nickel were considered at a local and provincial scale in the Metropolitan City of Turin. The concentrations data of the chemicals derived from the Regional Monitoring network (RMRAS) for the Metropolitan City of Turin and from local analyzes of Regional Agency for Environmental Protection (ARPA Piemonte) in the local site.The use of the RMRAS monitoring points was resulted inappropriate to define BVs in groundwater due to the low density of monitoring wells. On the contrary, the analyzes in the local study area made it possible to understand and characterize correctly numerous specific aspects, recognizing the diffuse pollution and identifying new potential punctual contamination.In conclusion, the study made it possible to define the BVs in groundwater at a local scale and to propose possible improvements of analysis methodology.