Phytoextraction of Trace Metals (Cd, Ni and Pb) by Panicum maximum Grown on Natural Soil

This study aims to assess the effective capacity of Panicum maximum to accumulate cadmium (Cd), nickel (Ni) and lead (Pb). P. maximum observed in a greenhouse was subjected to 2 ppm of Cd, 50 ppm of Ni, 100 ppm of Pb contaminated soil and uncontaminated soil, for 120 days. Plant growth and biomass produced concentration of trace metals in soil and plant, bioaccumulation and transfer factors, location of potentially toxic elements in tissues and cells of plant have been determined. Stem length and biomass produced by P. maximum were higher on the uncontaminated soil followed respectively by those of soil-contaminated by Pb, Cd and Ni. Bioaccumulation factors of trace metals were 8.93 (Pb), 8.47 (Ni) and 3.37 (Cd). Ni was more accumulated in shoot biomass (FT > 1), while Pb and Cd were concentrated in root biomass (FT < 1). Pb is accumulated preferentially in endodermis (roots) and epidermis (leaves). As for Ni and Cd, they are concentrated in central cylinder of roots and in conductive bundles of leaves. At cellular level, Ni and Cd are mainly concentrated in intracellular compartments of leaves and roots, while Pb is strongly detected at cell walls.

Phytoaccumulation Potential of Three Endogenous Poaceae Species Grown on the Akouedo Landfill (Abidjan, Côte d’Ivoire)

The selection of adequate plant species is a prerequisite for cleaning-up trace metal contaminated-soils by phytoaccumulation which is a cost-effective and environmentally-friendly technology. The potential of Panicum maximum, Eleusine indica and Cynodon dactylon to uptake trace metals from the soil of the Akouedo landfill was investigated. The concentrations of trace metals in soil were also considered. Moreover, the accumulation of Zn, Ni, Cu, Pb and Cd was assessed based on bioconcentration factor, translocation factor. The results showed high concentration values in the soil of the abandoned and the operation site of the landfill compare to the control site. The highest concentrations of trace metals in the plant shoot were observed with P. maximum for Ni. In root biomass, Zn, Cu and Cd showed high concentrations with P. maximum, E. indica and C. dactylon. Furthermore, the highest values of bioconcentration factor (BCF) and the translocation factor (TF) for Ni, were respectively 111.98 ± 82.45 and 4.26 ± 1.75 and were recorded with P. maximum. P. maximum, suggesting that it can be considered as a Ni hyperaccumulator.

Influence of Lead and Cadmium Concentration on the Accumulation Capacity of Panicum maximum

The restoration of soils polluted by trace metals (Pb and Cd) by phytoremediation is an innovative and ecologically sustainable solution. The objective of the study was to develop a process of phytoaccumulation of trace metals (Pb and Cd) in soils with the species Panicum maximum. For this purpose, 30 buckets containing soil were used. These included six (06) buckets per dose of soil contamination by Pb and Cd (3 mg/kg and 9 mg/kg of Cd and 100 mg/kg and 300 mg/kg of Pb) and six (6) buckets containing uncontaminated soil (control). During a period of 90 days of experimentation, the concentrations of trace metals in the plant biomass and in the soils were measured. Also, the bioaccumulation (BF) and translocation (TF) factors, the mass of Pb and Cd taken up by the plant were determined. The results showed that the biomass produced was negatively influenced by increasing Pb and Cd concentration. The concentrations of Pb and Cd accumulated by P. maximum varied in the aboveground biomass from 6.48 ± 0.55 to 18.09 ± 0.71 mg/kg (Pb100);from 10.93 ± 0.38 to 23.04 ± 0.79 mg/kg (Pb300);from 0.91 ± 0.02 to 1.50 ± 0.03 mg/kg (Cd3);and from 3.05 ± 0.08 to 5.43 ± 0.09 mg/kg (Cd9) from day 30 to day 90. However, in the root biomass, trace metals (Pb and Cd) ranged from 8.09 ± 0.58 to 22.57 ± 0.86 mg/kg (Pb100);from 29.45 ± 0.49 to 62.35 ± 0.82 mg/kg (Pb300);from 0.66 ± 0.01 to 1.11 ± 0.07 mg/kg (Cd3);and from 2.22 ± 0.08 to 3, 97 ± 0.09 mg/kg (Cd9), from day 30 to day 90. Pb was concentrated in the root biomass and Cd in the aboveground biomass. Bioaccumulation factor values ranged from 0.26 ± 0.02 to 0.99 ± 0.04 (Pb100);from 0.21 ± 0.04 to 0.50 ± 0.06 (Pb300);from 0.83 ± 0.09 to 1.72 ± 0.18 (Cd3);and from 0.70 ± 0.08 to 1.54 ± 0.18 (Cd9). High concentrations of Pb and Cd show a negative effect on the accumulation potential of P. maximum.