The impact of different root exudate components on phenanthrene availability in soil

Abstract

This study investigated the impact of different root exudate components (RECs) on the availability of phenanthrene as a representative of polycyclic aromatic hydrocarbons (PAHs) in soil (TypicPaleudalfs) using laboratory batch assays. Six typical RECs were compared including citric acid, oxalic acid, malic acid, alanine, serine, and fructose. An n-butanol extraction procedure and a sorption experiment were used to predict the availability of phenanthrene in soil. We found that both the n-butanol extraction and sorption process increased the availability of phenanthrene with increasing REC concentrations. The availability of phenanthrene in soil with various treatments decreased in the following order: organic acids (citric acid > oxalic acid > malic acid) > amino acids (alanine > serine) > fructose treatments. The mechanism of REC-influenced availability of PAH in soil is discussed based on the observed metal dissolution, soil organic matter reduction, and dissolved organic matter release from soil solids.