The effects of anion sorption on sorption and leaching of cadmium

The effect of chloride, sulfate, nitrate, and phosphate anions on the sorption and leaching of cadmium was examined in 2 soils (Manawatu silt loam and Egmont clay loam) which differ in their variable charge components. There was a larger sorption of cadmium in the presence of phosphate than in the presence of sulfate, nitrate, and chloride, and the difference was more pronounced in the Egmont soil. In soils, specific sorption of phosphate increases the negative charge. The increase in negative charge per unit amount of phosphate sorbed decreased with increasing phosphate sorption. The sorption of cadmium increased in response to phosphate sorption. The phosphate-induced cadmium sorption resulted from the increase in negative charge due to phosphate sorption. Column studies indicated that cadmium was less susceptible to leaching in the presence of phosphate than in the presence of nitrate.