土壤垂向异质性及离子强度对全氟辛酸在饱和农田土壤中运移行为的影响

全氟和多氟化合物(Perfluoroalkyl and Polyfluoroalkyl Substances,PFASs)污染已对农田土壤-地下水环境构成严重威胁,掌握农田土壤中PFASs运移行为对准确评估其环境风险具有重要意义.本研究以全氟辛酸(Perfluorooctanoic Acid,PFOA)为代表性PFAS...

Perfluorooctanoic acid transport in saturated farmland soil: Effects of vertical heterogeneity of soil properties and ionic strength

The occurrences of perfluoroalkyl and polyfluoroalkyl substances (PFASs) have posed serious risks to the farmland environment. A good understanding of PFAS transport in subsurface system is of considerable interest for accurately assessing their environmental risks. In this study, perfluorooctanoic acid (PFOA) was used as a representative PFAS and the effects of vertical heterogeneity of soil properties and ionic strength on its transport were systematically investigated in a paddy soil collected from Liuhe District of Nanjing. The results showed that the vertical heterogeneity of soil properties had a significant influence on PFOA transport in the saturated soil. Smaller PFOA retardation occurred with an increase in soil depth, due to the lower content of soil organic carbon. Higher ionic strength resulted in greater retardation of PFOA because the weak electrostatic repulsions between PFOA and soil surface and hence more adsorption/desorption of PFOA. Besides, a greater effect of ionic strength on PFOA retardation in upper layer of soil was observed. Therefore, it is essential to consider the coupled effect of vertical heterogeneity of soil properties and ionic strength in assessing PFOA transport under real conditions.