Nitrate in surface (187 samples) and ground (126 samples) waters collected in Sardinia (Italy) shows a large range of concentrations: from <1 to 249 mg/L. The highest median value of nitrate occurs in groundwater samples, especially in shallow wells, and spring waters circulating in granite environments. In surface waters, nitrate generally increases as flow increases following
intense precipitation. Main sources of nitrate in the studied waters might derive from agriculture and farming
