| Adsorption-desorption of inorganic mercury（HgCl2） and Methyl mercury（MeHg） in four different soils and the effects of pH on the adsorption were studied using batch equilibration techniques. The results showed that the adsorption-desorption isotherms of HgCl2 and MeHg in soils were fitted by the Freundlich empirical equation（r>0.98）. The adsorption coefficients Kf of HgCl2 in paddy soil, red soil, yellow brown soil, shajiang black soil were 122.25, 86.60, 70.95, 76.60, respectively; The Kf values of MeHg were 55.99, 45.00, 41.94, 40.43, respectively. The soils had the great adsorption capacity for HgCl2 and MeHg, and soil adsorption for HgCl2 was stronger than that for MeHg. The adsorption of HgCl2 and MeHg in soils increased with increase in the organic matter contents of the soil. The changes of soil initial pH could influence the adsorption of HgCl2, and the largest amount of adsorption took place under neutral conditions, but it had little effect on the adsorption of MeHg. The desorption of HgCl2 and MeHg from soils showed significant hysteresis effects which was indicated by the higher adsorption slope（1/nads） compared to the desorption slope（1/nads）. Soils that adsorbed more mercury also desorbed less mercury. |
