In order to investigate the effects of pH and organic matter content on cadmium adsorption and exchangeable cations desorption in soils, the adsorption isotherms of cadmium and the desorption isotherms of calcium and magnesium on four New Jersey soils at four pH values were plotted, and the cadmium partition coefficients (Kd) were also calculated. The slopes of cadmium adsorption isotherms dramatically increased with increasing solution pH. Judging from Langmuir adsorption equations, the maximum adsorption quantities (b) of cadmium at high pH values were much greater than those at low pH values for the same soil. The partition coefficients increased greatly with increasing solution pH. The slopes of regression equations between partition coefficients and pH values were steep in the order of the organic matter content of the soils. The correlation coefficients (r^2) between partition coefficient and organic matter content for 1 × 10 exp (-4) M increased from 0.3027 at pH 4.0 to 0.9964 at pH 8.5 and from 0.2093 at pH 4.0 to 0.9657 at pH 8.5 for 2×10 exp(-4) M Cd (NO3)2. The desorption quantities of calcium and magnesium decreased with increasing solution pH and increased with increasing cadmium adsorption.

• Byoung-Yoon PARK(Dept. of Environmental Health, Catholic University of Taegu-Hyosung) | 박병윤
• Hyung-Moo SHIN(Dept. of Environmental Engineering, Kyungsung University) | 신현무