NATURE BASED SOLUTIONS FOR RESTORING A MULTI-CONTAMINATED SOIL: A MICROCOSM STUDY WITH BRASSICA NAPUS

Over the years, many plant species have been studied to find the ones that can best be used in PlantAssisted BioRemediation (PABR) techniques. The PABR has established itself as one of the most ecosustainable and effective methods to recovery contaminated areas, thanks to the processes promoted by the interactions established between root system and soil rhizosphere microorganisms (Ancona et al. 2022). Plant species belonging to the Brassicaceae family are the most studied for the recovery of contaminated areas. The interest is due to their capability to be moderate tolerant to the contaminants present in the environment and to phytoextract pollutants (especially heavy metals), accumulating them in their epigeal tissues (Belouchrani et al. 2016; Angelova et al. 2017). Among these, the use of Brassica napus L. has been particularly thorough also due to the possibility of reusing its biomass for the production of secondary valuable products, such as oil for biofuel and ethanol (Park et al. 2012; Dhiman et al. 2016). To enhance the efficiency of PABR, the addition of organic amendments was extensively tested. In fact, it was studied that organic matters, such as compost or biochar, are useful to improve soil chemical-physical and microbiological properties and, consequently, to stimulate the pollutants' degradation or extraction (Ancona et al. 2022). In the present study, three series of soil microcosms have been performed at greenhouse scale. Brassica napus L. was growth in a soil historically contaminated by polychlorobyphenils (PCBs) and heavy metals (HMs). Compost and biochar were tested as amendments (10% and 2.5%, respectively). Three conditions were set up, each with and without plant, as control (Fig.1): contaminated soil, contaminated soil + compost, contaminated soil + biochar. At each sampling times (0, 60 and 90 days) each condition was analysed in triplicate. Chemical-physical analyses (pH, electric conductivity, available phosphorus, organic carbon), microbiological and molecular analyses (microbial abundance, community structure and dehydrogenase activity) and contaminants analyses (PCBs, HMs) were carried out on soil at the different sampling times. To evaluate the uptake, contaminants were also investigated in plant tissues (roots, stem, leaves and flowers).