Characteristics of Heavy Metal Migration In Farmland

Compared with water and air pollution, soil pollution is highly concealed, has poor self-purification ability, and has high risks associated with accumulation. Characteristics of heavy metal migration directly affect the quality of the environment, and comparative studies utilizing column leaching and natural leaching experiments have rarely been performed. In this study, we used farmland soil samples from Xiba Town in the Wutongqiao district to determine the differences in leaching characteristics between column leaching and natural leaching tests. The results indicate the following. (1)The release of heavy metals in soil is divided into two stages: the first stage is a rapid release period, while the leaching solution has an extremely low heavy metal concentrations during the second stage. The cumulative amount released during the second stage exhibits regular fluctuations, while the heavy metal release rate is consistent with the heavy metal adsorption properties of the soil. (2) The release and accumulation of heavy metals in the soil are influenced by many factors that may interact with each other, which leads to low correlations between the cumulative heavy metals released in the column leaching and natural leaching tests. Simulating natural heavy metal migration trends using the column leaching test is effective to some extent, but there are significant differences between the accumulation sites and accumulated amounts. This study provides a theoretical basis for improving the remediation of soil contaminated by heavy metals.