NO3EXCESS - Nitrogen Origin, EXport and Cycling in coastal irrigatEd SettingS

Abstract:

The issue of a continuous and increasing nitrogen (N) input represents one of the main threats affecting ecosystems, having significant and non-skippable impacts on surface and groundwater quality, greenhouse gas emissions, ecosystems and finally on human health. In this view, the Nitrogen Origin, EXport and Cycling in coastal irrigatEd SettingS project (hereafter NO3EXCESS) represents a multidisciplinary plan aimed at quantifying N loads in lowland agricultural settings by considering their origin, pathways, transformations, and impacts, with the final objective to identify and adopt the most effective countermeasures to reduce them.
The study area is the Po di Volano-Sacca di Goro watershed (PV), the terminal portion of the Po River Basin and a recently reclaimed deltaic territory. This basin suffers from high nutrient loads due to anthropogenic activities, together with water resources overexploitation, saltwater encroachment along the rivers and nutrient release from peaty lenses. For all the above-mentioned reasons the Po di Volano basin represents an optimal benchmark to validate the NO3EXCESS concept, since it could be considered as a representative example of the future for irrigated lowlands.
To reach its goal, NO3EXCESS workflow will be unfold by four main activities:

• field measurements will allow to identify the main biogeochemical processes governing N cycle and to build a detailed hydrological conceptual model;
• laboratory experiments will deepen the understanding of the processes acting in the field sites and allow their quantification to close the water and N budgets;
• numerical modelling will contribute to the validation of the conceptual model via an iterative approach that will employ 2D reactive transport models and 3D groundwater flow models. This approach will provide a point-by-point estimate of the water and N species export towards the lagoon, clarifying and quantifying the contribution of groundwater to N cycle;
• finally, the review of the available information will allow to evaluate the environmental and economic feasibility of diverse remediation strategies to control eutrophication and reduce greenhouse gas emissions in lowland coastal irrigated settings, with a particular focus on the conservative management of aquatic vegetation in the canal network as a tool for NO3- mitigation.

The adoption of a holistic approach to the N mass balance at the watershed scale will be possible thanks to the involvement of a multidisciplinary consortium having distinct and complementary expertise in water ecology, biogeochemistry, hydrogeology, hydrogeochemistry, soil science, stratigraphy, and numerical modelling.