The potential of the model crop Brassica napus L. (rapeseed) for the phytoremediation of soils polluted with metals was investigated at laboratory scale. The first step consists in the evaluation of the seed germination and growth of the Brassica napus L. plant in a controlled environment, followed by the determination of the photosynthetic pigments content represented by chlorophyll a and b and carotenoids. The degree of metal accumulation in rapeseed has been evaluated by the bioaccumulation factor (BAC), the bioconcentration factor (BCF) and the translocation factor (TF). Phytotoxicity tests were performed in Petri dishes with filter papers moistened with metal solutions in the range of 0 to 300 mg/L Pb(II) or Cd(II). At the highest concentration of the lead and cadmium treatments (300 mg/L), B. napus L. showed the lowest germination degree (56.67% and 43.33%, respectively). According to Tukey test results, Pb(II) concentrations of up to 300 mg/L do not significantly affect the length of the hypocotyls, whereas, in the case of Cd(II), the mean of the radicle and hypocotyl lengths of the seedlings are significantly affected compared to the mean of the control. In soil pot experiments, important changes have been obtained in the pigment content, especially in the case of cadmium. For both metals and for each treatment (100 to 1500 mg/kg Pb(II) and 1 to 30 mg/kg Cd(II)), a TF < 1 indicates an ineffective metal transfer from root to shoot. Finally, rapeseed can be considered a tolerant plant and a suitable candidate for Pb(II) and Cd(II) accumulation and for the phytostabilization of contaminated soil under the experimental conditions adopted in the present study.

For the protection of human and ecological receptors from the effects of soil pollution with chemical compounds, we need to know the behavior and transport of pollutants in soil. This work investigated the Congo red (CR) acid dye sorption on three natural soils collected from central and northeastern regions of Romania, symbolized as IS-65, IS-T, and MH-13. To define the mechanism of sorption and identify the rate governing step, various diffusion models such as Weber–Morris intraparticle diffusion, Boyd, film and pores diffusion, and mass transfer analysis have been verified. The intraparticle diffusion analysis of Congo red sorption onto soils has been described by a multi-linear plots, showing that the sorption process takes place by surface sorption and intraparticle diffusion in macro, meso, and micropores. The values of intraparticle diffusion coefficient k_id increased with any rise of the initial concentration of pollutant. The results show that the values of pore diffusion coefficient (D_p) and film diffusion coefficient (D_f) are found to be from 10⁻⁸ to 10⁻¹⁰ cm² s⁻¹, indicating that film diffusion influences the sorption rate limiting step. The intraparticle diffusion analysis shows that the plots did not pass through the origin and have two distinct parts, confirming that intraparticle diffusion is not the single determining mechanism involved in the sorption of Congo red on soils IS-65, IS-T, and MH-13. The results revealed that the sorption process has a complex nature, since both external diffusion and internal diffusion are involved in the sorption of CR from solution onto the investigated soils.