【摘要】 传统干湿交替对土壤污染物迁移行为的研究多聚焦于淹水过程，忽略了落干过程干燥温度的影响。该研究通过野外监测与室内控制实验相结合的方法，基于土壤胶体促运移的视角，探究干燥温度对土壤胶体释放以及多环芳烃迁移的影响机制。实验结果显示：土壤胶体释放量随温度升高而增加，高温组（35℃）相对于中温组（20℃）和低温组（5℃）分别增加了9.98%和50.29%；土壤胶体对单体菲(PHE)的吸附容量随着处理温度的升高而增加，高温组相对于中温和低温组分别增加了1.52%和7.20%。胶体促进了PHE在多孔介质中的迁移，且高温处理组PHE的迁移率（65.54%）显著高于中温（61.36%）和低温组（59.43%）,Pearson相关性分析表明，PHE的迁移率与胶体Zeta电位（P<0.01）、比表面积（P<0.01）、PHE吸附容量（P<0.01）呈极显著正相关性。说明温度驱动了土壤胶体Zeta电位和比表面积的改变，从而影响其对PHE的迁移，该结果可解释消落带土壤多环芳烃季节性分布差异的原因，为气候变化背景下土壤中PAHs的归趋提供了一定的理论依据。更多还原

【Abstract】 Current research on the environmental behavior of soil colloids under alternating wet and dry conditions mainly focuses on the influence of the “wet” process mediated by water, while there is a lack of systematic understanding of the mechanism of soil structure evolution-colloid release-pollutant migration caused by temperature fluctuations during the drying process. This study, based on the differences in temperature and the distribution of polycyclic aromatic hydrocarbons(PAHs)in the soil of water-level-fluctuating zone in the Three Gorges Reservoir area during different seasons, combined field monitoring with indoor controlled experiments. Through the dry-wet alternation-soil colloid release experiment and the colloidmediated pollutant migration experiment system, it revealed the influence mechanism of seasonal temperature changes in the Three Gorges Reservoir area on the release of soil colloids in the water-level-fluctuating zone and the migration of phenanthrene(PHE), a PAH monomer. The experimental results showed that the seasonal distribution of PAHs in the water-levelfluctuating zone was significantly correlated with the soil silt and sand content(P<0.05); the cumulative release of soil colloids increased with the increase in drying temperature, and temperature affected the release of soil colloids by influencing the soil particle size composition and Zeta potential. The cumulative release of soil colloids in the high-temperature group(35 ℃)increased by 9.98% and 50.29% compared with the medium-temperature group(20 ℃) and the low-temperature group(5 ℃),respectively. Soil colloids released under different drying temperatures significantly promoted the migration of PHE in porous media. Pearson correlation analysis indicated that the migration efficiency of PHE mediated by soil colloids was extremely significantly positively correlated with the Zeta potential of soil colloids(P<0.001), and highly significantly positively correlated with the adsorption capacity of soil colloids for PHE and the specific surface area of soil colloids(P<0.01). The migration rate of PHE in the high-temperature treatment group was 65.54%, significantly higher than that in the medium-temperature group(61.36%) and the low-temperature group(59.43%). This indicates that temperature affects the release and adsorption capacity of soil colloids by regulating the structure of soil aggregates and the physicochemical properties of soil colloids, ultimately leading to different migration efficiencies of PHE mediated by soil colloids at different drying temperatures, thereby causing seasonal differences in soil PAHs. The research results provide an important theoretical basis for the environmental fate, migration and transformation, and pollution control of PAHs in soil under the background of climate change.更多还原