Cadmium uptake by coconut palm and its sorption on soil in ionic medium

Mohotti, Anoma Janaki; Nadheesha Fathima, Muhammed Khalid; Priyantha,  Namal

Cadmium uptake by coconut palm and its sorption on soil in ionic medium

2021

Mohotti, Anoma Janaki | Nadheesha Fathima, Muhammed Khalid | Priyantha, Namal

Uptake of cadmium investigated from a solution of Cd(II) in 0.010 M KNO3 by coconut palm grown in soil, regularly supplied with different phosphate fertilizer sources, namely, triple super phosphate (TSP), imported rock phosphate (IRP), and Eppawala rock phosphate (ERP) for 17 years, indicates that the Cd levels of the soil with different treatments were less, at equilibrium state under laboratory conditions, than the maximum permissible limit of 0.05 mg/kg for agricultural soils. Further, coconut palm is found to uptake Cd from soil and translocate to leaf. The optimum equilibrium condition of soil with ionic solution was achieved after optimizing the parameters, such as shaking time, settling time, initial concentration and solution pH under laboratory conditions. The optimum values obtained are 6.0 h, 1.0 h, 0.70 mgL-1 and 5 – 7, respectively. Adsorption isotherm analysis depicts that multilayer sorption of Cd(II) on soil is more probable as the results of adsorption equilibrium are better fitted with the Freundlich model than the Langmuir model. This phenomenon highlights the fact that Cd in soil solution easily gets replenished upon sorption of Cd by the coconut palm.

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