Metal cation leaching affects soil aggregate stability via altering soil internal forces governed by specific ion effects during dry-wet cycles

Research hypothesis
We hypothesised that metal cation leaching induced by dry-wet cycles can affect soil internal force, thereby reducing aggregate stability, and specific ion effects playing critical roles throughout.

In this study, both drainage and non-drainage conditions were employed to elucidate the mechanisms of metal cation leaching on soil aggregate stability via altering soil internal forces during dry-wet cycles. Overall, our findings indicate that soil aggregate stability decreased as the metal cation are leached during dry-wet cycles. Specifically, metal cation leaching reduces the quantity of metal cations adsorbed onto soil colloid surfaces, thereby enhancing the net force between soil particles and consequently decreasing aggregate stability during dry-wet cycles. Repeated dry-wet cycles lead to the stabilization of metal cation leaching and the net forces of soil internal forces, which directly govern soil aggregate stability. Additionally, significant specific ion effects on soil aggregate stability were observed during dry-wet cycles, mediated by cationic non-classical polarization that alters soil internal forces. In summary, metal cation leaching affects soil internal force, thereby reducing aggregate stability during dry-wet cycles, with specific ion effects playing critical roles throughout.