Abstract: A three-dimensional model of predicting arsenic in water and sediment was constructed to scientifically evaluate the influence of arsenic on Zongtongka Reservoir after reservoir formation. The adsorption equilibrium of sediment on arsenic after reservoir impoundment was analyzed through isothermal adsorption test. The Guoduo Reservoir which is of similar hydrological and water quality conditions with Zongtongka Reservoir verified the model parameters and simulated the three-dimensional distribution of arsenic in different water periods after the Zongtongka Reservoir was impounded. Results revealed that after water storage, the sediment concentration and arsenic concentration of the reservoir both declined along the stream. Sediment concentration in wet season is larger than that in dry season, and sediment concentration in front of the dam in the surface is obviously smaller than that in the bottom; while arsenic concentration in wet season is smaller than that in dry season, and when the arsenic concentration in tributary is large, shore pollution zone will be formed. Arsenic concentration in front of the dam shows a significant increase from the surface layer to the bottom layer.

Key words: arsenic, partition coefficient, isothermal adsorption experiment, temporal and spatial distribution, Zongtongka Reservoir