Field-scale rhyzoremediation of a contaminated soil with hexachlorocyclohexane (HCH) isomers: the potential of poplars for environmental restoration and economical sustainability

Three pre-selected poplar clones and two soil HCH degrader micro-organisms have been experimentally applied in a contaminated agricultural soil in the basin of Fiume Sacco near to Rome for its reclamation. The aim was to successfully associate soil cleaning by rhizoremediation with an economically sustainable biomass for energy production of large poplar plantations. Plants and micro-organisms were selected for the best association with bacteria to obtain 1) the maximum HCH concentration reduction in soil, 2) the minimum plant contamination with HCH, and 3) the maximum biomass production. Results showed that an association between all these traits is possible in a specific poplar clone inoculated with a selected HCH degrader bacterium. The need for a pre-remediation phase in situ to select best candidate plants and bacteria with lowest HCH accumulation in its organs is emphasized. Rhyzoremediation associated with the safe thermo-convertible biomass production is confirmed as a sustainable recovery of soils interdicted to food-agricultural activities.