Solid-state 19F NMR investigation of hexafluorobenzene sorption to soil organic matter

Solid-state F-19 NMR observation of the sorptive uptake of hexafluorobenzene (HFB) by two peat samples gives direct spectroscopic evidence for the existence of dual-mode sorption to soil organic matter. The sorption process is shown to be rapid, with all applied HFB sorbed within a few hours. Extractable lipids compete for high energy sorption sites in the organic matter, and their removal increases the amount of rigidly sorbed, immobile species formed. Soil lipids enhance the sorption capacity of the solid-state dissolution domain of the organic matter. This dissolution domain is responsible for partitioning in the dual-mode phenomenon. Removal of the lipids decreases the partitioning capacity of the soil organic matter.