Perfluorooctanoic acid (PFOA) is an emerging persistent organic pollutant that threatens human health and ecosystems. However, the intricate mechanism of the change in PFOA transport behavior that interacts with Fe_xS_y minerals under groundwater-type differences is not clear. To address this knowledge gap, multi-scale experiments and multi-process reaction models were constructed to investigate the underlying mechanisms. The results showed that different groundwater (NO₃^-, Cl^--Na⁺, SO₄^2-, and HCO₃^- types) had significant effects on PFOA transport. NO₃^-, Cl^--Na⁺, SO₄^2-, and HCO₃^- decreased the retardation effect of PFOA in the Fe_xS_y media. Compared to other groundwater types, the adsorption sites of Fe_xS_y were the least occupied in the NO₃^- groundwater. This observation was supported by the least inhabition of λ in Fe_xS_y-NO₃^- interaction system, which demonstrated that more PFOA was in a high reaction zone and electrostatic repulsion was weakest. The surface tension of different ion types in groundwater provided evidence explaining the lowest inhibition in the Fe_xS_y-NO₃^- system. The 2D spatiotemporal evolution results showed that in Fe_xS_y with NO₃^- system, the pollutant flux (6.00 ×10^-5 mg·(m²·s)^-1) was minimal. The pollutant flux in the SO₄^2- groundwater system was 9.95-fold that in Fe_xS_y with the NO₃^- groundwater. These findings provide theoretical support for understanding the transport and fate of PFOA in Fe_xS_y transformations that interact with different types of groundwater.

Keywords: Groundwater types; Iron-sulfide mineral; PFOA; Transport and fate.

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全氟辛酸（PFOA）是一种新兴的持久性有机污染物，对人类健康和生态系统构成威胁。然而，PFOA与FeₓSy矿物质相互作用在不同类型地下水中其运输行为变化的复杂机制尚不清楚。为了填补这一知识空白，构建了多尺度实验和多过程反应模型来探究潜在机制。结果表明，不同类型的地下水（NO₃⁻、Cl⁻-Na⁺、SO₄²⁻ 和 HCO₃⁻）对PFOA的运输有显著影响。NO₃⁻、Cl⁻-Na⁺、SO₄²⁻ 和 HCO₃⁻ 均会降低FeₓSy介质中PFOA的滞留效应。与其他类型的地下水相比，在NO₃⁻地下水中，FeₓSy 的吸附位点占用最少。这一观察结果得到了 FeₓSy-NO₃⁻ 相互作用系统中λ抑制最小的支持，这表明更多的 PFOA 处于高反应区，并且静电排斥最弱。不同类型地下水中的离子表面张力提供了在 FeₓSy-NO₃⁻ 系统中抑制效果最低的解释依据。二维时空演化结果显示，在FeₓSy与 NO₃⁻ 地下水系统中，污染物通量（6.00 × 10⁻⁵ mg·(m²·s)⁻¹）最小。在SO₄²⁻地下水系统中的污染物通量是 FeₓSy 在NO₃⁻地下水中系统的9.95倍。这些研究结果为理解PFOA与不同类型地下水相互作用的FeₓSy转化过程中的运输和命运提供了理论支持。

关键词：地下水类型；铁硫化矿物；PFOA；运输与命运。

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