Abstract：Enrichment and migration of arsenic in groundwater are mainly controlled by the redox conditions in aquif er, sorption-desorption reaction on sediments and co-precipitation process of iron oxide. The immobilization process of As in aquifer with the addition of Fe ( Ⅲ) was studied by dynamic sand column experiment.Mechanism of reaction in process was explained by using SEM and EDX characterization methods. Deposition reaction kinetics results showed that cumulative deposition of Fe in the sandy aquifer media was 2. 469 g during the experiment process and the deposition rate was 50. 01%. It indicated that besides the convection-dispersion effects, the deposition was significant during the iron salts migration process in the sand aqueous medium. The migration rate of Fe ( Ⅲ) , As ( Ⅲ) and As ( V) in simulated aquifer media was 0. 0021, 0. 0108 and 0. 0091 times of groundwater flow rate, respectively. The curing rate of Fe for As ( Ⅲ) and As ( V) in the sand column was 1. 09 × 10^-3cm·h^-1and 7. 38 × 10^-4cm·h^-1. The thickness of curing arsenic band was 0. 722 cm and 0. 669 cm. The arsenic dynamic fixing quantity achieved 1. 7078 mg·g^-1and 2. 524 mg·g^-1. The results show that the physical and chemical conditions of high-arsenic aquifers can be exchanged artificially, such as through increasing the iron oxide content. Arsenic in aquifer may be fixed effectively. The release process is terminated and further migration process is prevented. Mechanism of the whole curing process depends on electrostatic and obligate adsorption between the hydrolysis products of Fe and As. The data obtained in this study is useful for in situ arsenic remediation in the future.

Keyword：arsenic;Fe (Ⅲ) ;migration rate;immobilization;adsorption;