Glomalin-related soil protein reduces the sorption of polycyclic aromatic hydrocarbons by soils

Large amounts of glomalin-related soil protein (GRSP) are present in the soil; however, the impacts of GRSP on the chemical process of soil polycyclic aromatic hydrocarbons (PAHs) are far under investigation. This research sought to elucidate the sorption of phenanthrene as a representative PAH by soils, including Kandiudult, TypicPaleudalf, and Mollisols with co-existing GRSP (0-50 mg/L). The results indicated that soil sorption capacities for phenanthrene reduced significantly. Notably, GRSP changed the sorption process of phenanthrene by Kandiudult, well described as the Freundlich model. In contrast, the phenanthrene sorption isotherms were well described with the Linear model for TypicPaleudalf and Mollisols. The reduced percentage of phenanthrene sorption due to GRSP addition was 7.01%-49.21%, 23.92%-68.71%, and17.26%-66.80% for Kandiudult, TypicPaleudalf and Mollisols, respectively. It was noted that GRSP has a strong capacity for phenanthrene sorption in aqueous solutions and elevates the availability of phenanthrene for microorganisms or plants. During the sorption process, the introduction of GRSP resulted in the reduction of organic matter in soils and elevated the concentrations of dissolved organic matter in solutions, which was the primary mechanism of GRSP-reduced phenanthrene sorption by soils. The findings revealed that GRSP enrichment can increase the mobility of PAHs in contaminated soils.