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<p>In the Treviso province (Veneto, Italy) most of the drinking water (nearly 60 %) is supplied from wells located in the northern piedmont area, where agricultural activities are developed using chemical plant protection products (chemical PPPs). In this area the aquifer interested by the groundwater extraction is unconfined, making the subsurface water resource intrinsically vulnerable to any PPP or PPP residue (metabolite) leaching from the agricultural soil to the groundwater table, and raising concerns about the consequences of a possible groundwater contamination on the health of the local inhabitants.</p> <p>To protect the drinking water resource, in 2019 the Veneto Region provided a technical framework for the definition of the wellhead protection areas (WHPAs, Resolution 1621) in accordance with the EU directives 2000/60 and 2006/118, related to the establishment of safeguard zones for the water bodies used for drinking water supply.  In the WHPAs the use of PPPs is only allowed when accounting for the vulnerability of the groundwater and the well extracting water for human consumption. </p> <p>To define the vulnerability of wells supplying drinking water, a procedure that considers the tridimensional behavior of a possible contaminant is suggested, taking into account the mobility of the chemical species across the vadose zone, the total amount of PPPs applied on the soil, and combining the probability of contaminant infiltration with the groundwater pathlines reaching the well.</p> <p>An application has been developed in the piedmont area of the Treviso province where a geospatial analysis of the vine-specific PPPs sales data identified over 30 WHPAs potentially affected by the PPPs use. </p> <p>The 3D vulnerability assessment couples the position of the vulnerable WHPAs retrieved from the geospatial analysis with 1) the data related to the infiltration capacity of agricultural and not-agricultural unsaturated soils in the piedmont area of the Treviso province, 2) the mobility of the vine-specific PPPs, and 3) the groundwater pathlines in the superficial phreatic aquifer obtained by physically-based numerical modeling.</p> <p>This research has been funded by the contribution from the UNI-IMPRESA 2021 joint research project (Centre of Hydrology ‘Dino Tonini’ - University of Padua, Alto Trevigiano Servizi Spa, Piave Servizi Spa): Subsurface Water quality and Agricultural pracTices monitoring 2 (SWAT-2).</p>

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<p>The multidisciplinary research project SWAT - Subsurface Water quality and Agricultural pracTices monitoring - has been set up to assess pesticides contamination risks for groundwater in the hills of Prosecco in the north-east of Italy. The unconfined aquifer underneath the typical Glera grape-variety vineyards of Valdobbiadene and Conegliano is used as water supply resource for human consumption. The principal aim of the project SWAT is to obtain a thorough information on the impact of contaminants coming from agricultural practices and infiltrating in the soil of well protection areas. Based on specifically designed field experiments, a study on water and solutes infiltration process is developed to understand the movement and evolution of chemical species in the vadose zone. A one-dimensional transport model for unsaturated media (BRTSim - Maggi, 2015) is used to simulate solute infiltration and estimate the soil hydraulic parameters. Monitoring activities started in November 2018 in two experimental sites (the Settolo site in Valdobbiadene and the Colnù site in Conegliano) near supply wells surrounded by vineyards. A mixture of Bromide and Glyphosate was identically applied on two parcels of 25 m<sup>2</sup> for each experimental site to obtain information about spatial heterogeneity and to collect independently water and soil quality measurements. Porous cups, for the collection of infiltrating water, and capacitive sensors, to gauge temperature and Volumetric Water Content (VWC), were installed beneath the sectors at three depths (-0.1, -0.3, -0.7 m). In each site meteorological station provides hydrological data. At first, laboratory analysis on soil samples collected at the same depths gave a vertical distribution of the sector-specific soil texture that was used as input for Rosetta to obtain initial estimations of retention curve behaviour and the saturated hydraulic conductivity. These data allowed us to develop an open-loop simulation using the early meteorological observations as hydrological forcing. As the laboratory analysis on soil and water samples proceed and the number of in-situ measurements increases, different data windows are tested to improve the performances of the calibration procedure performed using PEST. In all tests a spin-up procedure is applied to mitigate the dependency of the results on the imposed initial data by repeating the first month of hydrological forcing three times. The results of the transport model using Rosetta parameters are already satisfactory in terms of VWC trends even if they are considerably shifted respect to the measured values. The calibration reduces the gap between model results and observations, but the behaviour seems to get worse in dry conditions. Improvements are achieved in the upper layer (-0.3 m) applying evapotranspiration along the root zone. The Bromide simulations agree with the infiltration behaviour: its movement is well represented up to -0.3 m, while at -0.7 m the observed values are overestimated. Ongoing investigations on the glyphosate dispersion process show limited infiltrating mass in the water collected samples.</p>

<p>Broad contamination of systemic herbicide glyphosate –GLP– (N-(phosphonomethyl) glycine) and its metabolite aminomethylphosphonic acid (AMPA) in soil and water has become one of the main environmental issues worldwide, raising awareness of the potential harmful effects to human health and ecosystems. Physical, chemical, and biological soil properties contribute to the complex interaction between GLP and the environment, that makes any prediction of adsorption, transport, and degradation dynamics still challenging.</p><p>Within a wide project –SWAT– that tries to link GLP and AMPA dynamics through the vadose zone with groundwater contamination, the specific goals of this work are: 1. monitoring soil and water contamination of GLP and AMPA in agricultural lands; 2. identifying the driving factors leading to site-specific soil-water contaminant interactions.</p><p>Two experimental sites were located in northeastern Italy (Conegliano and Valdobbiadene municipalities) in the winegrowing terroir of the Prosecco wine production, recently included in the UNESCO’s World Heritage List. Each site was equipped with two soil-water monitoring stations (25 m<sup>2</sup> each), multi-sensor soil probes (temperature and water content) and suction lysimeters to monitor the full soil profile. Undisturbed soil cores were also collected and later analyzed for hydraulic, physical and chemical properties down to 70 cm. After GLP field contamination on November 2018 (0.188 g m<sup>-2</sup>), soil and water were systematically sampled from each site, starting immediately after contamination and thereafter at each rain event for 6 months. Adsorption coefficients (K<sub>f</sub>) were estimated in laboratory in order to get information about GLP sorption to soil particles at different soil layers along the full soil profile. Site-specific dissipation kinetics (DT<sub>50</sub>) were also evaluated to better understand its decay rate.</p><p>First results revealed that GLP transport was highly site specific and locally affected by preferential flows when intense rainfall events occurred (12 mm h<sup>-1</sup> max rainfall intensity): GLP showed strong binding affinity to soil particles in the topsoil layer and it likely bypassed the porous matrix towards the deepest layers, where it was detected as in the surface one. The GLP dissipation dynamic was completed after 6 months of experimentation, whereas AMPA was still detected in the topsoil layer, attesting the full degradation after almost 300 days. Site-specific laboratory and field data will be integrated and further discussed to better understand the fate of glyphosate and AMPA in the vadose zone.</p>