Abstract
This study aims to estimate critical concentrations of cadmium (Cd) and lead (Pb) in the soil which negatively affect growth of Eucalyptus camaldulensis Dehnh. seedlings, and to estimate some phytoextraction parameters for heavy metals (HM) from the soil to evaluate efficiency of seedlings in their potential use in phytotechnology to improve the environment with phytoremediation. Eucalyptus seedlings were treated with Cd concentrations 0, 25, 55, 85, and 110 mg kg-1 dry soil as CdCl2, and Pb concentrations 0, 125, 250, 450, and 550 mg kg-1 dry soil as PbCl2, and the experiment was designed using the completely randomized design (CRD) as a two-factor factorial experiments and the data were analyzed using SAS system. Results showed that the highest percentage decrease in dry weight of stems, leaves and roots were 55, 68.6, and 67.2%, respectively, at the interaction (110 Cd and 550 Pb) mg kg-1 dry soil compared with control, and Cd concentrations in stems, leaves and roots ranged between (0.375-372.167), (0.417-128.167) and (0.583-162.083) mg kg-1, respectively and Pb concentrations in stems, leaves and roots ranged between (9.583-62.375), (10.042-20.417) and (2.875-73.500) mg kg-1. It was found that values of translocation factor (TF), biological accumulation coefficient (BAC), bioconcentration factor (BCF) and concentration index (CI) for Cd ranged between (0.611-4.239), (1.333-28.790), (0.383- 16.840) and (1-490.812) respectively, and values of TF, BAC, BCF, and CI of Pb ranged between (0.275-5.702), (0.769-4.246), (0.295-7.539) and (1-3.833) respectively, and tolerance index (TI) values ranged between (0.370-1). We concluded that Eucalyptus seedlings are suitable for phytoextraction applications within phytoremediation processes of soils contaminated with Cd and Pb.
Highlights
Environmental pollution is the presence in the environment of any pollutant substance in the environment in quantities that directly or indirectly, alone, or by the interaction with others, harms public health or causes the ecosystems to disrupt or stop them from performing their normal role in the ecosystem, and the soil is contaminated by containing a substance or substances in high concentrations that threaten human, animal or plant health or disturb the natural standards of surface and groundwater
Where a study was conducted on Poplar hybrids in Serbia for Populus deltoides for clone (B-81) and Populus × euramericana for clone (Pannonia) on the possibility of phytoremediation of soils contaminated with Cd using, which were treated with a concentration of Cd 8.14 mg kg-1 dry soil, the study showed that the decrease in biomass production was significantly greater in Pannonia than in B-81 [42]
The direct effect of high concentrations of heavy metals caused no significant difference was observed with the cellular stress, which resulted in inhibition of value 59.433 g at the interaction (550 Pb and zero Cd) mg kg-1, and the values of this study root growth that resulted from inhibition of root cell division and reduced nutrient absorption outperformed the results reported by Nofal et that affected the dry mass of the roots [54]
Summary
Environmental pollution is the presence in the environment of any pollutant substance in the environment in quantities that directly or indirectly, alone, or by the interaction with others, harms public health or causes the ecosystems to disrupt or stop them from performing their normal role in the ecosystem, and the soil is contaminated by containing a substance or substances in high concentrations that threaten human, animal or plant health or disturb the natural standards of surface and groundwater. Heavy metals are considered the most dangerous pollutants to the environment of living organisms, resulting from the remnants of technologies created to serve humanity such as mining, factories, electric power stations, agricultural pesticides, hospitals, sewage waste, human consumption waste, means of transportation, and the mineral origin of the earth's crust [5, 57]. They affect proteins and enzymes, some of which are genotoxic and carcinogenic substances that affect the chemical composition of DNA, as well as inhibit the process of genetic reproduction. Studied Alkhatib et al [4] the effects of Pb on growth rate, physiological and biochemical characteristics in Leucaena leucocephala seedlings, as the results showed that the effect of Pb led to a decrease in growth rate of seedlings treated with concentrations 300, 500 and 700 μM, whereas Pb concentrations of 25, 50 and 100 μM did not show any toxic effect on seedlings
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