Effect of Elemental Sulphur on Uptake of Cadmium, Zinc, and Sulphur by Oilseed Rape Growing in Soil Contaminated with Zinc and Cadmium

A pot experiment was conducted to study the influence of elemental sulphur (S0) on cadmium (Cd), zinc (Zn), and sulphur (S) uptake by oilseed rape (Brassica napus L.) grown in a calcareous soil contaminated with either Cd or Zn or with both Zn and Cd together. Elemental sulphur was applied at two rates (0 and 200 mmol), Cd at two rates (0 and 20 mg), and Zn at three rates (0, 20, and 200 mg) kg−1 soil. Cadmium (as CdCl2) and Zn (as ZnCl2) were added in solution to soil prior to planting. After 10 days, S0 and fertilizer were thoroughly mixed and added to the soil. Plants were harvested after growing for 40 days in a greenhouse. Soil pH and shoot dry weight decreased significantly in response to S0 application. Addition of Zn and Cd did not influence plant growth without S0 supply. Shoot concentrations of Zn and Cd increased significantly with Zn and Cd addition as well as S0 supply. Cadmium addition did not lead to any change in shoot Zn concentration. Shoot Cd concentration decreased in the 200 mg kg−1 Zn addition treatment compared with the control but remained unchanged in all Zn treatments when S0 was applied. Shoot S concentration increased with application of S0, Zn, and Cd. Shoot Zn and Cd uptake by oilseed rape increased significantly with the Zn and Cd addition. However, shoot Zn removal did not increase significantly, and Cd removal decreased when S was applied. In conclusion, S0 acidified the soil and increased shoot concentrations of Zn and Cd, but its depressive effect on shoot biomass was so pronounced that it would not enhance phytoextraction of Cd or Zn from this soil by oilseed rape.