Overcome the limits of multi-contaminated industrial soils bioremediation: Insights from a multi-disciplinary study.

Phytoremediation can be a promising and sustainable strategy to recovery Potentially Toxic Elements (PTEs) contaminated soils. However, at the field level, this tool can be limited by many issues. Herein, we combined native plant species with different cover type (mono and poly culture) in an in-field mesocosm experiment for the remediation of multi-contaminated soils from Bagnoli brownfield site (Southern Italy). We preliminary gain insights about the physical, chemical and biological features of the soils and subsequently induced a potential variation in the soil microbiome. We found that polyculture better respond both in terms of pollutant phytostabilization efficiency and from a stress tolerance perspective. Among plant species, Festuca achieved the best performance due to the overexpression of metal transporters able in both PTEs influx and sequestration from the cytoplasm. We achieved a site-specific bio-factory, which represents a strategy for the sustainable and relatively fast recovery of large contaminated areas.

Identification of native-metal tolerant plant species in situ: Environmental implications and functional traits.

A study was undertaken to identify suitable native plants for the phytoremediation of the second largest integrated steelworks in Italy (Bagnoli brownfield site). A phytoecological survey allowed us to identify 139 plant taxa belonging to 58 different families. The most represented families were in the decreasing order Poaceae > Fabaceae > Asteraceae > Apiaceae. The biological spectrum showed a predominance of Therophytes > Hemycriptophytes > Phanerophyte. Seventy-six sites were selected on the presence of colonist's plants and vegetation assemblage patterns. At each site, roots and leaves of the dominant plant and rhizosphere soils were sampled. Total content of metal(loid)s in soils and plant parts were determined. Agronomic soil parameters were studied. Anthropogenic sourced metal(loid)s were discriminated from geochemical ones, and plant metal(loid) accumulation and translocation efficiency were evaluated. The role of many native plant species in terms of TEs phytomanagement strategy was recognizable inside the investigated area. According to this survey of structural plant diversity, several combinations between plants and microorganisms are being further investigated to identify relevant biological system for the phytomanagement of this contaminated area.

Investigation and Assessment for an effective approach to the reclamation of Polycyclic Aromatic Hydrocarbon (PAHs) contaminated site: SIN Bagnoli, Italy.

Native plant species were screened for their remediation potential for the removal of Polycyclic Aromatic Hydrocarbons (PAHs) contaminated soil of Bagnoli brownfield site (Southern Italy). Soils at this site contain all of the PAHs congeners at concentration levels well above the contamination threshold limits established by Italian environmental legislation for residential/recreational land use, which represent the remediation target. The concentration of 13 High Molecular Weight Polycyclic Aromatic Hydrocarbons in soil rhizosphere, plants roots and plants leaves was assessed in order to evaluate native plants suitability for a gentle remediation of the study area. Analysis of soil microorganisms are provides important knowledge about bioremediation approach. Alphaproteobacteria, Betaproteobacteria, Gammaproteobacteria are the main phyla of bacteria observed in polluted soil. Functional metagenomics showed changes in dioxygenases, laccase, protocatechuate, and benzoate-degrading enzyme genes. Indolacetic acid production, siderophores release, exopolysaccharides production and ammonia production are the key for the selection of the rhizosphere bacterial population. Our data demonstrated that the natural plant-bacteria partnership is the best strategy for the remediation of a PAHs-contaminated soil.