Monitoring the Efficiency of Rhazya stricta L. Plants in Phytoremediation of Heavy Metal-Contaminated Soil

Abstract

Heavy metal-contaminated soil constitutes many environmental concerns. The toxic nature of heavy metals poses serious threats to human health and the ecosystem. Decontamination of the polluted soil by phytoremediation is of fundamental importance. Vegetation is an appealing and cost-effective green technology for the large-scale phytoremediation of polluted soils. In this paper, a greenhouse experiment was carried out to test the potential of Rhazya stricta as a heavy metal phytoremediator in polluted soil. Plants were grown for three months in pots filled with soils treated with the heavy metals Cd, Pb, Cu, and Zn at rates of 10, 50, and 100 mg/kg. The bioaccumulation factor (BCF) and translocation factor (TF) were calculated to detect the ability of R. stricta to accumulate and transfer heavy metals from soil to plant organs. The results showed that under increasing levels of soil pollution, the bioconcentration of Cd and Zn heavy metals showed the highest values in plant roots followed by leaves, whereas in the case of Pb and Cu, roots showed the highest values followed by stems. Heavy metals accumulation was higher in roots than in stems and leaves. The BCF of Zn reached the highest values in roots and stems for 10 mg/kg soil treatment, followed by the BCFs of Cd, Cu, and Pb. The TF for the different heavy metal pollutants’ concentrations was less than unity, suggesting that the plants remediate pollutants by phytostabilization. The TF values ranged from higher to lower were in the order Zn > Cu > Cd > Pb. The rapid growth of R. stricta and its tolerance of heavy metals, as well as its ability to absorb and accumulate metals within the plant, recommends its use in the phytoremediation of slightly polluted soils in arid lands by limiting the heavy metals transport.

Effect of Lead and Copper on Photosynthetic Apparatus in Citrus (Citrus aurantium L.) Plants. The Role of Antioxidants in Oxidative Damage as a Response to Heavy Metal Stress

“…Heavy metals remaining in the soil play a significant role in the induction of plant stress [ 29 ]. Plants in order to resist this kind of stress developed a number of strategies including efflux pumps, sequestration in cells and in intracellular compartments, heavy metals binding into the cells and strong ligands production such as phytochelation.…”

The Accumulation Risk of Heavy Metals in Vegetables which Grown in Contaminated Soil

“…Bioconcentration factor (BCF) has been calculated as the ratio of the metal concentrations in plant roots to that in the soil according to the following equation, BCF = C harvested tissue / C soil Where C harvested tissue is the metal concentration in the plant roots and C soil is the metal concentration in the soil (22).…”

“…Translocation factor (TF) has been calculated as the ratio of the metal concentration in the shoots to that in the roots. TF = C shoot / C root Where C shoot is the metal concentration in the plant shoots (stems or leaves) and C root is the metal concentration in the plant roots (22). Cd concentration in the soil has been within the range of ND-2.98 mg/kg dry wt.…”

“…The results in accordance with Badr et al (30), they tested the ability of several native plants for HMs phytoextraction and found that all tested species accumulated higher HMs concentrations within their root tissues. This finding could be due to physiological damage of elevated HMs concentration in the roots, which consequently reduced its ability to translocate the HMs to aerial parts (22).…”

Potentiality of Azolla pinnata R. Br. for Phytoremediation of Polluted Freshwater with Crude Petroleum Oil

“…At present, phytoremediation is gaining global attention as a promising environmental restoration technology owing to its advantages over the established conventional cleanup techniques. These advantages include capital costs, reasonable remediation efficiency and lower environmental risks than conventional technologies [25][26][27][28][29][30][31]. The phytoremediation of environments containing organic pollutants has been studied by different methods using plants and microorganisms [32][33][34][35].…”