Impacts of heterogeneous organic matter on phenanthrene sorption: Different soil and sediment samples

Organic petrography has been proposed as a tool for characterizing the hete rogeneous organic matter present in soil and sediment samples. A new simpli fied method is proposed as a quantitative means of interpreting observed so rption behavior for phenanthrene and different soils and sediments based on their organic petrographical characterization. This method is tested under singe solute conditions and at phenanthrene concentration of 1 mug/L. Sinc e the opaque organic matter fraction dominates the sorption process, we pro pose that by quantifying this fraction one can interpret organic content no rmalized sorption distribution coefficient (K-oc) values for a sample. Whil e this method was developed and tested for various samples within the same aquifer, in the current study the method is validated for soil and sediment samples from different sites that cover a wide range of organic matter ori gin, age, and organic content. All 10 soil and sediment samples studied had log K-oc values for the opaque particles between 5.6 and 6.8. This range o f K-oc values illustrates the heterogeneity of opaque particles between sit es and geological formations and thus the need to characterize the opaque f raction of materials on a site-by-site basis.