Influence of nano‐Al ₂ O ₃ on the migration of heavy metal Cr in the unsaturated soil

Chromium(VI), a kind of migratory heavy metal pollutant, does not only accumulate in the soil in huge amount, but it can also migrate to the deep layer soil and even contaminate the groundwater. The migration pattern of water in the unsaturated silt loam is studied. Then the dynamic leaching characteristic of Cr(VI) is observed. Finally, through the indoor soil column leaching experiment, the influence of adding nano‐aluminium oxide (Al ₂ O ₃ ) into the soil column on the migration of Cr(VI) in the silt loam is analysed. In unsaturated silt loam, water in it apparently affects the Cr migration. The deeper the soil layer is, the lower the Cr(VI) concentration is. With the drip irrigation going on, the Cr(VI) concentration in the soil increases constantly until it fundamentally reaches the saturated adsorbance of the soil. With nano‐Al ₂ O ₃ added into the column, the migratory rate of Cr(VI) in the soil decrease obviously, which is probably because of the space steric effect and adsorption characteristics of nano‐Al ₂ O ₃ . Therefore, nano‐Al ₂ O ₃ can be utilised as a preferable material to reduce the migration rate of Cr(VI) of soil and groundwater. The research results can supply the theoretical basis to the research of heavy metal pollution in the unsaturated soil.