A distributed reactivity model for sorption by soils and sediments. 12. Effects of subcritical water extraction and alterations of soil organic matter on sorption equilibria

Subcritical water extraction was used as a tool to remove the carboxylic, aliphatic, and carbohydrate types of organic carbon from a humic soil. The rates and extents of soil organic carbon removal were quantified as functions of superheated water temperature, phase, and exposure time. The experimental data suggest that superheated water effects deoxygenation/aromatization reactions of soil organic matter that mimic those of geologically slow, natural diagenesis processes. Phenanthrene sorption and desorption equilibrium isotherms far the altered soils were measured. The sorption isotherms were characterized by increasing capacity and nonlinearity with increasing degree of polar functionality removal and simulated diagenesis of the soil organic matter.