Influence of PAH speciation in soils on vegetative uptake of PAHs using successive extraction

Polycyclic aromatic hydrocarbon (PAH) speciation in soils and the relationship between PAH speciation in soils and the accumulation of PAHs in vegetables have rarely been reported. In this study, the organic solvent extractable PAHs in soils, PAHs that bind to endogenetic soil humus, soil properties, and PAHs in B. chinensis were comprehensively studied. Mobile fulvic acid (FA) and crude humin preferred adsorbing 3-ring and 4-ring PAHs whereas stable humic acid (HA) preferred adsorbing 5-ring PAHs. The PAH speciation in soils was in the order of organic solvent extractable PAHs (59.08%)>humin-bound PAHs (26.20%)>FA-bound PAHs (10.03%)>HA-bound PAHs (4.68%). The relative amounts of FA-bound PAHs versus HA-bound PAHs were linked to soil type. FA-bound PAHs and humin mineral-bound PAHs had a positive correlation with fine particles and were preferentially accumulated in B. chinensis. Other speciation was preferentially retained in soils and adsorbed onto the surface of and within coarse particles. The PAHs in vegetables were ideally forecasted using solvent extractable PAHs, FA-bound PAHs, and soil properties (silt, moisture, and pH). The FA-bound PAHs were more soluble in water and can be easily taken up by plants together with water and nutrients.