Groundwater nitrate contamination and agricultural land use: A grey water footprint perspective in Southern Apulia Region (Italy)

In this paper, we present a new approach based on the Grey Water Footprint (GWF) concept for the determination of groundwater nitrate contamination, with a focus on the agricultural impact in the Southern Apulia Region (Italy). The GWF assessment allows us to highlight wells where nitrate contamination is higher and for which a verification of the nature of contamination is necessary, potentially identifying certain contexts associated with risk factors present in the area. Data show higher nitrate GWF values for vineyards than for olive groves, particularly in areas used for the production of table grapes. Indeed, it is possible to observe that the Western Ionian-Tarantino arch is characterized by a high average level of the GWF indicator, area characterized by an agricultural land use (vineyards, orchards, simple arable land). Another important area is the Brindisi plain, predominantly characterized by an agricultural vocation and a related fertilizer use. The situation in the whole Salento peninsula is more heterogeneous. The results of the GWF show high values in equally distributed points with a clear frequency in the coastal areas of the Ionic arch (Eastern Tarantino and Salento). The Water Footprint methodology and in particular the GWF approach used in this study conceives a useful indicator for the agricultural policy planning processes, a criterion to establish land use management according to the status of hydrological basin and a tool for assessing the pollution monitoring programs. [Display omitted] •Agricultural land uses affect groundwater resource status in terms of nitrate contamination.•The GWF results show high values with a clear frequency in the coastal areas of the Ionic arch.•High GWF values correspond to crops requiring a significant nitrogen surplus for their cultivation.•High GWF values are signs of higher nitrogen surplus in the areas covered by vineyards.•Groundwater quality requires specific agricultural management practices and land use policies.