吕雪艳,孙媛媛,吴吉春.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[J].环境科学学报,2021,41(7):2849-2856
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
- Perfluorooctanoic acid transport in saturated farmland soil: Effects of vertical heterogeneity of soil properties and ionic strength
- 基金项目：国家自然科学基金（No.42077109，42007114）；江苏省自然科学基金青年基金（No.BK20200817）
- 吕雪艳
- 1. 南京大学地球科学与工程学院, 南京 210046;2. 南京信息工程大学水文与水资源工程学院, 南京 210044
- 孙媛媛
- 南京大学地球科学与工程学院, 南京 210046
- 吴吉春
- 南京大学地球科学与工程学院, 南京 210046
- 摘要：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PFASs，选用南京市六合区水稻土为供试土壤，系统探究了土壤垂向异质性及离子强度对PFOA在不同深度农田土壤运移行为的影响.结果表明：土壤垂向异质性显著影响PFOA在不同深度饱和土壤中运移行为，土壤深度增加使PFOA运移迟滞性显著降低，原因是土壤有机质含量随深度增加而减小，PFOA与土壤间疏水作用减弱.离子强度增加导致PFOA运移阻滞性明显增强，这是由于高离子强度使土壤与PFOA间静电斥力减弱，PFOA在土壤表面吸附和解吸量均显著增加.此外，离子强度增加，上层土壤中PFOA阻滞变化程度显著大于下层土壤，表明离子强度对PFOA运移阻滞性的影响与土壤深度有关.因此，为准确预测和评估实际农田土壤中PFOA运移行为，必须考虑到土壤垂向异质性及离子强度的耦合影响.
- Abstract：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.
