Use of 3-D hydrologic modelling and UAV-photogrammetry to characterize the phytoextraction efficiency of poplar trees in a cadmium contaminated agricultural field.

The accumulation of non-essential heavy metals in agricultural soils and consequent environmental contamination raises concerns over their potential toxic effects on human health. Unfortunately, over the past years, the Campania Region (Southern Italy) has been subjected to illegal dumping of industrial or household waste. Particular attention is devoted toward the National Interest Priority Site (NIPS) Domitian Coast Flegreo and Agro Aversano because it is characterized by a patchy distribution of anthropogenic and geogenic pollutants. Contrary to other heavy metals, Cadmium (Cd) is of considerable environmental concern. Industrial and agricultural applications of cadmium include the production of batteries, alloys, and pigments and chemical fertilizer and pesticides[1]. Poplar is suitable to absorb and accumulate Cd in its roots and is usually used for phytoremediation of contaminated soils [1]. Nevertheless, direct determination of Cd in poplars roots is an expensive, time-consuming and destructive activity. To circumvent the drawbacks of conventional direct approach, scenario-based strategies obtained by using advanced hydrological modelling tools, like the HydroGeosphere (HGS) model, have been developed to examine both contaminants transport in groundwater and solute surficial distribution in a 3D environment. HGS model accuracy is strongly influenced by detailed information on surface topography, commonly described by a Digital Elevation Model (DEM). A high resolution DEM was generated by applying Unmanned Aerial Vehicles (UAVs)that allows to set the flight quotas by adapting the aerial photos resolution to the object under investigation, and to acquire images in flexible date [2]. All in all, UAVs reduce also time and costs in retrieving aerial data [2]. In the present work, the assessment of Cd removal made by phytoextraction of poplars is evaluated by combining the HGS model with a fine resolution DEM, generated by UAV – photogrammetry. To achieve this aim, two different scenarios have been compared: the former is characterized by bare soil (BS), while the latter considers poplar plantation (PP).