The effects of soil/sediment organic matter on mineralization, desorption, and immobilization of phenanthrene

The bioavailability, desorption profiles, and extent of immobilization of phenanthrene were assessed using three geosorbents that had been previously classified based on their relative sorption behaviors and the chemical characteristics of their associated organic matter. Contaminants sorbed to amorphous, geologically young sorbents were found to desorb at a faster rate and thus be more readily bioavailable than contaminants sorbed to geologically mature kerogens. However, the final extent of mineralization in biologically active systems was observed to be comparable for all three geosorbents tested regardless of geological age. Analysis of the geosorbents at the conclusion of the mineralization experiments implies that biological activity affects contaminant immobilization through both sequestration and transformation. Dimensional analysis of the experimental system with independent measures of phenanthrene degradation and mass transfer aided in interpretation of the mineralization data by providing a quantifiable parameter. The resulting dimensional parameter not only changes with experimental design, but also was found to change as experimental conditions changed within a single system.