Abstract: The adsorption and polymerization of dissolved silicate on minerals affect its stability in the aquatic environment. The study of silicate chemistry on mineral surfaces is theoretically and practically important to understand the polymerization behavior and effect on its stability. In this work, the adsorption kinetics of dissolved silicates on scorodite was investigated, their polymerization behavior was characterized by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), and the stability of the silicate adsorbed scorodite was analyzed. The results showed that the adsorption of silicates by scorodite could be attributed to chemical adsorption and replacement reaction. Higher amount of silicate absorbed by scorodite at pH 3 and 4 and the ATRFTIR results also indicated that the adsorbed polymeric silicates on scorodite surface showed a structure similar to silicic acid (SiO₂·xH₂O). In addition, the leaching stability test showed that the amount of arsenic leached out from silicate absorbed scorodite was decreased by 68.1%, 52.5% and 15.5% at pH 4, 6 and 8 respectively, compared with that from scorodite. The findings in this work may have important implications for further stabilizing and reserving the arsenic containing residue from the metallurgical industry to reduce their environmental risk.

Key words: manipulation experiment, foliar litter decomposition, temperate forest, snow depth