The effects of anion sorption on sorption and leaching of cadmium

The effect of chloride, sulfate, nitrate, and phosphate anions on the sorpt ion and leaching of cadmium was examined in 2 soils (Manawatu silt loam and Egmont clay loam) which direr in their variable charge components. There w as a larger sorption of cadmium in the presence of phosphate than in the pr esence of sulfate, nitrate, and chloride, and the difference was more prono unced in the Egmont soil. In soils, specific sorption of phosphate increase s the negative charge. The increase in negative charge per unit amount of p hosphate sorbed decreased with increasing phosphate sorption. The sorption of cadmium increased in response to phosphate sorption. The phosphate-induc ed cadmium sorption resulted from the increase in negative charge due to ph osphate sorption. Column studies indicated that cadmium was less susceptibl e to leaching in the presence of phosphate than in the presence of nitrate.