State Environmental Protection Key Laboratory of All Material Fluxes in River Ecosystems, College of Environmental Sciences and Engineering, Peking University, Beijing, 100871, PR China.
State Environmental Protection Key Laboratory of All Material Fluxes in River Ecosystems, College of Environmental Sciences and Engineering, Peking University, Beijing, 100871, PR China.
Environ Pollut. 2023 Aug 15;331(Pt 2):121862. doi: 10.1016/j.envpol.2023.121862. Epub 2023 May 21.
The fate and transport behavior of microplastics (MPs), emerging colloidal contaminant ubiquitous in natural environments, would be greatly affected by other copresent pollutants. PFOA (emerging surfactant pollutant) would interact with MPs after encounter with them in natural environments, which could alter the transport behavior of both pollutants. Relevant knowledge is still lacking, affecting accurate prediction the fate and distribution of these two emerging contaminants in natural porous media. The cotransport behavior of different surface charged MPs (negatively/positively charged, CMPs/AMPs) with PFOA (three concentrations ranging from 0.1 to 10 mg/L) in porous media in both 10 and 50 mM NaCl solutions thus was investigated in the present study. We found PFOA inhibited CMPs transport in porous media, while enhanced AMPs transport. The mechanisms leading to the altered transport of CMPs/AMPs caused by PFOA were found to be different. The decreased electrostatic repulsion between CMPs-sand induced by the decreased CMPs negative zeta potentials via the adsorption of PFOA led to the inhibited transport of CMPs in CMPs-PFOA suspension. The enhanced electrostatic repulsion between AMPs-sand due to the decreased positive charge of AMPs via the adsorption of PFOA together with steric repulsion induced by suspended PFOA resulted in the increased transport of AMPs in AMPs-PFOA suspension. Meanwhile, we found that the adsorption onto MPs surfaces also impacted the transport of PFOA. Due to the lower mobility of MPs than PFOA, the presence of MPs despite their surface charge decreased the transport of PFOA of all examined concentrations in quartz sand columns. This study demonstrates that when MPs and PFOA are co-existing in environments, their interaction with each other will alter the fate and transport behavior of both pollutants in porous media and the alteration is highly correlated with the amount of PFOA adsorbed onto MPs and original surface properties of MPs.
微塑料（MPs）是一种新兴的胶体污染物，在自然环境中普遍存在，其归宿和迁移行为将受到其他共存污染物的极大影响。全氟辛酸（PFOA，一种新兴的表面活性剂污染物）在自然环境中遇到 MPs 后会与之相互作用，从而改变这两种污染物的迁移行为。由于相关知识的缺乏，这会影响到对这两种新兴污染物在自然多孔介质中归宿和分布的准确预测。本研究因此考察了不同表面带电 MPs（带负电/正电，CMPs/AMPs）与 PFOA（三个浓度范围为 0.1 到 10mg/L）在 10 和 50mM NaCl 溶液中在多孔介质中的共迁移行为。结果发现，PFOA 抑制了多孔介质中 CMPs 的迁移，而增强了 AMPs 的迁移。发现 PFOA 导致 CMPs/AMPs 迁移行为改变的机制是不同的。由于 PFOA 的吸附导致 CMPs 负 ζ 电位降低，从而减少了 CMPs-砂之间的静电排斥，导致 CMPs-PFOA 悬浮液中 CMPs 的迁移受到抑制。由于 PFOA 的吸附导致 AMPs 的正电荷减少，以及悬浮的 PFOA 引起的空间排斥，使得 AMPs-砂之间的静电排斥增强，导致 AMPs-PFOA 悬浮液中 AMPs 的迁移增加。同时，我们发现 MPs 表面的吸附也会影响 PFOA 的迁移。由于 MPs 的迁移性低于 PFOA，尽管 MPs 带电荷，但它们的存在会降低所有考察浓度的 PFOA 在石英砂柱中的迁移。本研究表明，当 MPs 和 PFOA 同时存在于环境中时，它们之间的相互作用会改变这两种污染物在多孔介质中的归宿和迁移行为，这种改变与吸附到 MPs 上的 PFOA 量以及 MPs 的原始表面性质高度相关。
