论文部分内容阅读
Interactions between anions and cations are important for understanding the behaviors of chemical pollutants and their potential risks in the environment.Here we prepared soil aggregates of a yellow paddy soil from the Taihu Lake region,and investigated the effects of phosphate (P) pretreatment on adsorption-desorption of Cu2+ of soil aggregates,free iron oxyhydrates-removed soil aggregates,goethite,and kaolinite with batch adsorption method.The results showed that Cu2+ adsorption was reduced on the aggregates pretreated with low concentrations of P,and promoted with high concentrations of P,showing a V-shaped change.Compared with the untreated aggregates,the adsorption capacity of Cu2+ was reduced when P application rates were lower than 260,220,130 and 110 mg/kg for coarse,clay,silt and fine sand fractions,respectively.On the contrary,the adsorption capacity of Cu2+ was higher on P-pretreated soil aggregates than on the control ones when P application rates were greater than those values.However,the desorption of Cu2+ was enhanced at low levels of P,but suppressed at high levels of P,displaying an inverted V-shaped change over P adsorption.The Cu2+ adsorption by the aggregate particles with and without P pretreatments was well described by the Freundlich equation.Similar results were obtained on P-pretreated goethite.However,such P effects on Cu2+ adsorption-desorption were not observed on kaolinite and free iron oxyhydrates-removed soil aggregates.The present results indicate that goethite is one of the main soil substances responsible for the P-induced promotion and inhibition of Cu2+ adsorption.