[Effect of pH on copper sorption by the loess and its species].

To study the effect of pH on copper sorption and species, loess was taken as sorbent in this research, and control experiments were conducted with quartz. All the curves of sorption amount-pH showed three regions, namely, sorption amount increased slowly at low pH, then increased quickly with the rise of pH, and reached the maximum amount at high pH. Copper of sorbed, exchangeable and bound to carbonate decreased with the increase in sediment concentration at constant Cu concentration, and increased with the increase in Cu concentration at constant sediment concentration. The MINTEQA2 model results showed that the proportions of precipitates and their compositions were different for loess and quartz, and the proportions of precipitates decreased with the concentrations of loess.