Summary In this work, effects of anion adsorption and pH on the electrokinetic properties of constant charge soils and variable
charge soils were studied. Yellow Brown soil and Phaeozem were used as representatives of constant charge soils, and Latosol was used as representative of variable charge soils. The results showed that the zeta Potential of Latosol
particles which had adsorbed different anions changed to negative from positive in sign with the increase in pH and an isoelectric point (IEP) occurred on all the zeta potential-PH curves. In the pH range of 3.5-8.0, the absolute value of change in seta potential of Latosol particles adsorbed different anions was of the order HPO2-4 > F- > SO2-4 > Cl- > NO3- The zeta potentials of yellow brown soil and Phaeozem particles referred as constant charge soil were always negative in sign and no IEP occurred on zeta potential-pH curves. The shape of zeta potential-PH curves varied with the soil type, the anion kind and the pH. In the pH range of 5.5- 9, the absolute value of change in zeta potential of yellow brown soil and Phaeozem which had adsorbed different anions was of the order SO2-4 > HPO2-4->F-> Cl- > NO-3