Suitable plant species are able to accumulate heavy metals and to produce biomass useful for non-food purposes. In this study, three endemic Mediterranean plant species, Atriplex halimus, Portulaca oleracea and Medicago lupulina were grown hydroponically to assess their potential use in phytoremediation and biomass production. The experiment was carried out in a growth chamber using half strength Hoagland's solutions separately spiked with 5 concentrations of Pb and Zn (5, 10, 25, 50, and 100 mg L(-1)), and 3 concentrations of Ni (1, 2 and 5 mg L(-1)). Shoot and root biomass were determined and analyzed for their metals contents. A. halimus and M. lupulina gave high shoot biomass with relatively low metal translocation to the above ground parts. Metals uptake was a function of both metals and plant species. It is worth noting that M. lupulina was the only tested plant able to grow in treatment Pb50 and to accumulate significant amount of metal in roots. Plant metal uptake efficiency ranked as follows: A. halimus > M. lupulina > P. oleracea. Due to its high biomass production and the relatively high roots metal contents, A. halimus and M. lupulina could be successfully used in phytoremediation, and in phytostabilization, in particular.

Metals are very common contaminants in the soil. High-yielding biomass crops offer good potential for the phytoremediation of soils contaminated with heavy metals. Biomass fuel crops grown on contaminated land have several advantages as site remediation combined with bioenergy production. In this context, two energy crops, Sorghum bicolor and Carthamus tinctorius, were grown hydroponically to assess their potential use in phytoremediation of nickel (Ni), lead (Pb) and zinc (Zn) and biomass production. The experiment was carried out in a growth chamber using half-strength Hoagland's solution spiked separately with five concentrations for Ni, Pb and Zn (between 5 and 100 mg L -1 ). Shoot and root biomass were determined and analyzed for their metals contents. Results showed that the tested plants were able to uptake Ni, Pb and Zn. Furthermore, roots accumulated more metals than shoots. Ni seems to be more toxic than Zn and Pb. In fact, both species were unable to grow at Ni concentration above 10 mg L -1 . Metal toxicity ranked as follows: Ni [ Zn [ Pb. High toxicity symptoms and biomass reduction were observed at concentrations of Pb and Zn above 25 mg L -1 for both species. S. bicolor was more efficient than C. tinctorius in metal uptake due to the high biomass production and the relatively high shoot concentration of metal. S. bicolor could be successfully used in phytoremediation applications in marginal soils with moderately heavy metal contamination. However, results obtained through the hydroponic experiment need to be confirmed by field experiments.

Agricultural practices, particularly land use, inputs and soil management, have a significant impact on the carbon cycle. Good management of agricultural practices may reduce carbon emissions and increase soil carbon sequestration. In this context, organic agricultural practices may have a positive role in mitigating environmental burden. Organic olive cultivation is increasing globally, particularly in Italy, which is ranked first worldwide for both organic olive production and cultivated area. The aim of the present study was to assess the effects of agricultural practices in organic and conventional olive systems on global warming potential (GWP) from a life cycle perspective and to identify the hot spots in each system. The impacts assessed were associated with the efficiency of both systems at sequestering soil in order to calculate the net carbon flux. There was a higher environmental impact on GWP in the organic system because of higher global greenhouse gas (GHG) emissions resulting from manure fertilisation rather than the synthetic foliar fertilisers used in the conventional system. However, manure was the main reason behind the higher soil organic carbon (SOC) content and soil carbon sequestration in the organic system. Fertilisation activity was the main contributor to carbon emissions, accounting for approximately 80% of total emissions in the organic system and 45% in the conventional system. Conversely, given the similarity of other factors (land use, residues management, soil cover) that may affect soil carbon content, manure was the primary contributor to increased SOC in the organic system, resulting in a higher efficiency of carbon sequestration in the soil following the addition of soil organic matter. The contribution of the manure to increased SOC compensated for the higher carbon emission from the organic system, resulting in higher negative net carbon flux in the organic versus the conventional system (-1.7 vs -0.52tCha-1 year-1, respectively) and higher efficiency of CO2 mitigation in the organic system