## 4 Discussion
[32] in seeds an hemp oil of Finola cultivar obtained in field trial. In the unpolluted site, Pb values in roots and stems were similar to contents observed in Site 3 whereas higher values were observed especially for leaves: in the latter case Pb did not differ between site 3 and 5. The higher value of Pb observed in the aerial parts of plants in Site 5, especially in leaves and seeds, cannot be explained by the translocation into the plants from the soil (phytoextraction), but probably was due to the atmospheric deposition. Indeed the presence of HMs from the atmosphere was confirmed by previous monitoring by the local regional environment agency [59] that reported remarkable deposition of air polluting metals as Pb and Zn. The Cd concentration in tissues of plants grown in the polluted site was higher in leaves than stems and roots. Significant lower values were observed for seeds. The Cd values detected for stems, roots and seeds (3.0-4.0 mg kg\({}^{-1}\)) were similar to those reported by [PERSON] et al. [31] and [PERSON] et al. [70] but lower than concentrations reported for _Cannabis sativa_ by others [27; 30; 71]. Except for the leaves, Cd values in tissues of plants grown in the unpolluted site were low and often below the detection limits. In general, in this study, higher values of Zn were observed in plants than for Cd and Pb. The highest concentrations of Zn relative to those of Pb were observed in the aerial parts of plants in this study, in agreement with that reported by [PERSON] et al. [29]. The Cd in soil was the pollutant contained in lowest values, while in plants the concentrations were similar to those of Pb. In contrast, the Pb values in soil were 60-80 times higher than those of Cd. The plant uptake of Cd and Pb could be limited by the low mobility in soil of those elements. The uptake of Zn, as well as their mobility, could be favoured by the biological utilization. Several factors related to plant and soil, such as genetic, edaphic or climatic factors, could be involved in the plant metal uptake and translocations [7; 15]. In this regard, to explore the capability of bioconcentration and translocation of the _Cannabis_ species, and of the cultivars, the cultivation should be monitored during several repeated experimental years in the field. The results showed _Cannabis sativa_ had a limited capacity to accumulate Cd and Pb in its biomass. The low values of these metals in marketable plant fractions, as stems, seeds, or flowers, to the exclusion of feed or food uses, make it interesting to explore the use of the biomass obtained from polluted soils for several supply chains. A more complete examination of these aspects can be carried out in the next years of the CANOPAES project activities. Among the various sectors that may be interested for the use of the biomass produced in these areas, excluding the food sector, the energy sector (for example the use in anaerobic digestion plants) could be one of the most promising [21]. The energy production by hemp could allow, at the same time, the reduction of waste and cost disposal in landfills. This study reported the first results of the CANOPAES project that aims to enhance the cultivation of hemp in soil polluted by metals in the Sardinia Region (Italy). The results obtained by the intensive soil characterization, integrated previous information, and boosted new knowledge for stakeholders interested in cultivation of metal polluted agricultural soil. By the study of pollutants in plant and soil, a close relationship between them was observed in some cases, but an unknown source of metal deposition in non-contaminated soils was also suggested. These first results could support the cultivation of industrial hemp in agricultural soils polluted by metals under semiarid climates.