Influence of Chloride Salinity on Cadmium uptake by Nicotiana tabacum in a Rhizofiltration System

A hydroponic trial was conducted to study the effect of chloride salinity in simulated effluent on Cd accumulation by tobacco. Leaf surface area (LSA) and root surface area (RSA) measurements were incorporated as possible determinants of Cd uptake rate by plants. Results showed that individual plant differences in Cd content were normalized when including RSA to express Cd uptake rates by plants but not including LSA. A biotic ligand model (BLM) fitted to predict Cd uptake, estimated active and almost linear uptake of the free Cd2+ ion by tobacco plants, while virtually no changes in the chloride complex (CdCl+) uptake were predicted, presumably due to a rapid saturation of the hypothetical root sorption sites at the concentrations used in this trial. Nicotiana tabacum var. K326 is evidenced to be a species potentially suitable for biological wastewater treatment using rhizofiltration at concentrations commonly found in salt-affected wastewater, with high Cd accumulation (185 to 280 mg/kgdm) regardless of water salinity and tolerance up to 80 mmol/L NaCl.