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Cd and Hg phytoremediation from soil using Miscanthus x giganteus

Chemical and physical treatments of contaminated arable soil can be useful in reclaiming almost all soil functions in ecosystem, except as a substrate for plant growth. There is a need for less expensive technologies which could remediate soil, without affecting fertility. Such method is phytoremediation, which uses plants that can remove, stabilize or degrade heavy metals in soil. The aim of this paper was to study the cadmium and mercury phytocharacteristics (bioavailability) from soil polluted with different levels of metals using Miscanthus x giganteus in terms of biomass quality and quantity. The use of bioenergy plants as an innovative strategy in phytotechnology gives additional benefits, like mitigation and adaptation to climate change, except soil remediation. Rhizomes from three years old M. x giganteus were planted in March 2014 and 3 vegetative years were studied. Experiment was set up as a randomized complete block design and the treatments varied in concentrations of Cd (0, 10 and 100 mg/kg soil) and Hg (0, 2 and 20 mg/kg soil) added to the soil. Soil has silt loam texture, acid pH value (pHKCl=5.12) and was weakly humic (SOM=2.26 %) with CEC of 18.4 cmol+/kg. Macronutrient content were very weak and weak, for available P (26 mgkg-1) and K (74 mgkg-1) and good supply in total N (0.12 %). Yield values ranged from 6.3 (L1+SS and L2) tDM/ha observed in 2017 up to 15.5 (C) tDM/ha in 2015 and were significantly different between treatments and years. Cadmium mass ratio in plants varied from 45 µg/kg (C, 2015) up to 6758 µg/kg (L2, 2016), Hg varied from 8.7 µg/kg (C and L1) measured 2015 up to 108.9 µg/kg (L2) observed 2016 and values between treatments and years were significantly different. M. x giganteus can accumulate and remove very modest content (up to maximal) 49 g Cd/ha per year (observed on L2 2016) and 0.79 g Hg/ha per year (revealed on L2 2016) in aboveground biomass. Finally, it can be concluded, due to obtain data that Miscanthus, as a valuable energy crop, is a potential candidate for the process of phytostabilization and biomass production on soils contaminated with Cd and Hg.

pollution, agricultural soils, heavy metals, phytostabilization

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