The role of ionic interfacial behaviors in formation of soil organic-inorganic complexes

Interactions between soil organic matter and mineral surfaces are ubiquitous. Research on soil organic-inorganic complexes has received much attention. The association of soil organic matter and mineral has been related to the stability of soil carbon pool directly, and this is of great significance to the environmental sciences and agricultural resource utilization. However, the mechanism of the formation of soil organic-inorganic complexes has far remained from perfect, and the link of interaction mechanism at the macroscopic, mesoscopic, and microscopic scales of soil have not been reasonably explained. Therefore, this paper discussed the formation of organic-inorganic composite colloids (formation theory, action mechanism and influencing factors) and the interfacial behavior of ions in this process. It systematically combed the mechanism of ions in the formation of soil organic-inorganic complexes and recalled advanced technologies of studying the interaction between soil organic and inorganic components. Finally, the paper summarized the role of ion-specific effects on the formation of soil organic-inorganic complexes. In particular, different ions with the same valence had different effects on the properties and processes of soil systems. This meant that slight differences between the number and arrangement of the outer electrons were amplified in the strong electric field near the soil surface, which enhanced effective charge of ions and coulombic force on ions by polarization. The effective charge number of ions was used to quantify the strength of ion interaction at the interface during soil colloids association. The conclusions were that soil organic-inorganic complexes improved the complex formation theory of soil organic-inorganic aggregates, provided theoretical basis for soil fertility and bioremediation, promoted environmental chemistry regarding soil organic-inorganic complexes and advanced research on particulate pollutant migration dynamics.