Monitoring and modelling the role of phytoremediation to mitigate non-point source cadmium pollution and groundwater contamination at field scale

This study evaluates the effectiveness of a phytoremediation technique developed within the framework of the EU-Life+ EcoRemed project and used to remove potentially toxic elements (PTEs) from some agricultural sites of the Campania Region in southern Italy. The methods discussed here should be viewed as a proof-of-concept and their potential is shown at the “Trentola” test site contaminated by low concentrations of cadmium. Advanced monitoring equipment together with modeling tools, based on the Richards and advective-dispersive equations. Coupling field monitoring and computer modeling is employed to estimate water flow and solute transport in the soil-vegetation-atmosphere system, with specific emphasis to assess the fate of the contaminant towards the groundwater. The role exerted by the EcoRemed phytoremediation protocol is evaluated by comparing two scenarios: 1) a bare soil only condition (BS scenario), and 2) a distributed phytoextraction activity obtained by planting poplar trees (Populus nigra spp) (PP scenario). The HYDRUS-1D code is used to model water flow and contaminant transport at soil-plant scale. The results showed the importance of using cost-effective monitoring devices to calibrate the soil parameters to properly describe the movement in the rhizosphere. Sensitivity analyses enabled specific features of the phytoextraction process to be identified. Moreover, especially with the aim of transferring the gained knowledge to public bodies and stakeholders, the scenarios based on 1-D numerical simulations should be conveniently complemented with simulations carried out at the scale of the entire field area, as shown in this study using the three-dimensional HydroGeoSphere (HGS) code.