Characteristics of heavy metal migration in farmland

Compared with water and air pollution, soil pollution is highly concealed, has poor self-purification ability, and poses 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 of the Wutongqiao District to determine the differences in leaching characteristics between column leaching and natural leaching tests. The results indicated that the heavy metals were released in two stages, a rapid release followed by a slow release stage. The cumulative amount released during the second stage exhibited regular fluctuations, while the heavy metal release rate was consistent with the heavy metal adsorption properties of the soil. In addition, the release and accumulation of heavy metals in the soil were influenced by many factors that may interact with each other, which could lead to low correlations between the cumulative heavy metals released during the column leaching and natural leaching tests. Simulating natural heavy metal migration trends using the column leaching test was effective to some extent, but there were significant differences between the accumulation sites and accumulated amounts. This study provides a theoretical basis for improving the remediation of soils contaminated by heavy metals.