Controls on dissolved organic matter stabilization: sorption as a potential process
doi: 10.5455/faa.82636 PP: 21 – 46
Dissolved organic matter (DOM) can be regarded as a good indicator of a healthy soil ecosystem as it is comparatively much more responsive than total organic carbon to the environmental changes. It controls most important physical and biochemical processes both in terrestrial and aquatic ecosystems. The movement of DOM in soils could be restricted by its adsorption to surfaces of minerals available in the soils. The aim of this review is to gather and synthesize the literature on the quantity and quality as well as stabilization process of DOM in soil. Various processes have been proposed, including anion exchange, ligand exchange, cation bridging, hydrogen bonding, van der Waals forces for describing DOM-mineral associations. But still there is a challenge to describe and evaluate these mechanisms clearly and quantitatively in different soil types and ecosystems. The extent and rate of sorption of DOM depends on the mineralogy, quality of OM and soil solution. There is limited literature on the quantitative connection between mineralogy and chemical properties of adsorbed DOM, especially for the assessment of diverse DOM-mineral interactions. The reversibility of sorbed OM is also needed to be studied more considering the effect of DOM properties and changing environmental conditions. Most of the research on DOM-mineral interactions focused on the limited natural ecosystem (mainly temperate forest, grassland or stream etc.). Thus, there is still great scope to investigate the controls of DOM dynamics and stabilization in soils of different use and management, and also in different climate zones other than temperate area.
Keywords: Dissolved organic carbon, carbon flux, organic carbon stabilization, organo-mineral interaction.