Areal and vertical distribution of nitrate concentration in Piedmont plain aquifers (North-Western Italy)

Abstract

Several areas in Piedmont plain (North-Western Italy) are characterized by nitrate concentrations higher than 50 mg/L, the maximum nitrate concentration accepted by Italian law. The Piedmont plain sector is the most important water reservoir of the Piedmont Region, due to its size, the characteristics of its deposits and the possibility of recharge. In the Piedmont plain groundwater, the origin of nitrate contamination is due to the increasing amount of synthetic nitrogenous fertilizers and organic manure used for agricultural purposes but also to septic tank effluents input. Univariate and bivariate statistics and concentration maps were used to describe the distribution of nitrate in Piedmont plain, both in shallow and in deep aquifers, to highlight the variation of nitrate levels from year 2000 to 2012 and to analyse the relation of nitrate versus well depth. The purpose is to create the basis for future investigations and insights about the nitrate sources and the attenuation processes in aquifers.