Diffusion Behavior of PAHs in the Soil of Water Level Fluctuation Zone during the Dry-Wet Alternation Process in the Three Gorges Reservoir Area
The study,by using a fugacity-diffusion model,investigated the diffusion behavior of typical polycyclic aromatic hydrocarbons(PAHs)monomer phenanthrene(PHE)and pyrene(PYR)in soil in water fluctuation zone of Xiangxi Bay in the Three Gorges Reservoir Area.The results demonstrated that the concentrations of PHE and PYR in the soil gradually decreased during the dry-wet alternating processes,eventually reaching a stable state.The fugacity fraction of PHE and PYR increased gradually after two cycles of wetting and drying,with PHE having a higher fugacity fraction and a higher risk of release than PYR.Significant changes were observed in the physical and chemical properties of the soil:pH increased by approximately 11.48％and 12.30％after two inundation periods,while total organic carbon(TOC)decreased by 40.90％and 24.75％,respectively.The proportion of soil particles with a particle size of＞2～50 μm decreased by approximately 7.70％and 4.90％after two inundation periods,whereas the proportion of soil particles with a particle size rang of ≤2 μm increased by approximately 7.20％and 5.30％,respectively.The activities of catalase(CAT)andβ-glucosidase(BGL)decreased in the range of 0.14～0.07 and 67.42～43.01 μmol·h-1·g-1,respectively,due to the changes in PAHs and TOC concentrations during the dry-wet alternating process.Pearson correlation analysis revealed extremely significant positive correlations between the concentrations of PHE and PYR in the soil with TOC concentration(P＜0.01),and significant positive correlations with BGL concentration(P＜0.05)and with the proportion of soil particles with a particle size range of＞2～50 μm(P＜0.05).Conversely,a significant negative correlation was observed with the proportion of soil particles with a particle size range of ≤2 μm(P＜0.05).
the Three Gorges Reservoir Areawater level fluctuation zonedry-wet alternationpolycyclic aromatic hydrocarbonsdiffusion behavior
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