The isotopic composition of nitrates from underground and surficial waters of Italy: a valuable tool for benefiting in the fight against pollution

Abstract

A review of isotopic data of nitrates in groundwater mainly from wells located in northern and central Italy has been carried out. A subordinate number of data refers to surface waters from the Po plain area. Most of the sampling areas, that are located in the proximity of important human settlements, are devoted to intensive agriculture and, thus, isotopic data indicate that the nitrogen source is mainly represented by mineralized synthetic fertilizers. A subordinate source is composed of either the soil organic fraction and animal manure used as a fertilizer. Only for a few water samples, the origin from sewage seep is suggested. Denitrification can occur in many aquifers, contributing to abate significantly nitrate concentrations in waters. Lastly, the absence of isotopic data for the waters from uppermost Regions of southern Italy and Sicily represents a major handicap in the fight against nitrate pollution, making the maps of nitrate risk in those areas not fully useful.