Can't tell a book by its cover: disjointed groundwater contamination and land use in an alluvial aquifer of Northern Italy

Abstract

In the Po plain, intensive agriculture is supported by large irrigation volumes and use of fertilizers. We analysed the effects of different land uses in a sector of the Mincio River on groundwater hydrochemical characteristics and hypothesized local regulation of NO3- contamination. In the unconfined coarse-grained alluvial aquifer, hydraulic heads were measured monthly in 17 wells from May 2019 to December 2019, to trace how the aquifer recharge and manure spreading influence groundwater physico-chemical parameters and quantity. The experimental site was divided into two different zones on the left and right bank characterized by different land use. Although these dissimilarities concern different irrigation and fertilization practices, we measured in both areas nitrate (NO3-) contamination in groundwater, with concentrations exceeding legislative limits by a factor of 2. Our results suggest that NO3- contamination in this area is not only driven by specific land use and related agricultural practice; rather, other local factors intrinsic to the local aquifer and groundwater characteristics play an important role. Presented results on groundwater quality and quantity provide useful information to increase knowledge on local N dynamics and to the administrations regulating fertilizer use in this area, already reported as Nitrate Vulnerable Zones (NVZ).