Distribution and Biodegradation of Nonextractable Polycyclic Aromatic Hydrocarbons in Particle-Size Aggregates of Field-Contaminated Soils

Adsorption on soil organic matter (SOM) and physical entrapment are the main mechanisms of nonextractable residue (NER) formation of polycyclic aromatic hydrocarbons (PAHs) in soil. Due to the SOM characteristics and pore structure in particle-size aggregates being different, the environmental fates of PAH NERs should be different as well. It’s valuable to understand the distribution and biodegradation of PAH NERs in soil particle-size aggregates. Three field-contaminated soils (Phaeozems, Anthrosols, and Calcareous soil) were separated into four particle-size aggregates (coarse sand, fine sand, coarse silt, and fine silt). The contents, compositions, and biodegradation of parent PAH NERs in particle-size aggregates were studied. Moreover, the effects of soil physico-chemical properties on the distribution and biodegradation of PAH NERs in particle-size aggregates were analyzed. The percentages of PAH NERs to total PAHs in particle-size aggregates were in the range of 6.7–9.8