农业农村部环境保护科研监测所土壤有机污染生物消减团队探讨酞酸酯污染条件下纳米塑料官能团对其在饱和含水介质中迁移的影响机制，相关成果发表于Chemosphere（IF = 7.086）。

Highlights

•PSNPs−NH₂ transport was hindered in GT and GT-DEHP-coated columns.

•GT and GT-DEHP decelerated the transport of PSNPs−COOH more than that of PSNPs.

•Deposition of PSNPs−NH₂ was largely due to its sensitivity to chemical heterogeneity.

•Quantum chemical computation was applied to study NPs transport for the first time.

•Ligand exchange caused greater deposition of PSNPs−COOH than that of PSNPs.

Abstract

The production and degradation of plastic remains can result in nanoplastics (NPs) formation. However, insufficient information regarding the environmental behaviors of NPs impedes comprehensive assessment of their significant threats. In this study, the transport behavior of unmodified NPs (PSNPs), carboxyl-modified NPs (PSNPs−COOH), and amino-modified NPs (PSNPs−NH₂) was investigated using column experiments in the presence and absence of goethite (GT) and diethylhexyl phthalate (DEHP). Quantum chemical computation was performed to reveal the transport mechanisms. The results showed that GT decreased the transport of NPs and the presence of DEHP decreased it further. Van der Waals forces and small electrostatic interactions coexisted between the PSNPs and GT and caused deposition. Ligand exchange caused greater deposition of PSNPs−COOH on GT-coated sand than that of PSNPs. Although hydrogen bonding existed between the DEHP and NPs with functional groups, an increase in the positive charge and chemical heterogeneity of the collector was the main reason for DEHP promoting the deposition of NPs. Because of low absolute negative zeta potential values, PSNPs−NH₂ was sensitive to chemical heterogeneity, and thus fully deposited (over 96.9%) in GT and GT-DEHP-coated columns. Generally, the deposition of NPs due to chemical heterogeneity was more significant than that due to the formation of chemical bonds and van der Waals, electrostatic, and hydrogen interactions. Our results highlight that the surface charge and functional groups significantly influence the transport behaviors of NPs and elucidate the fate of NPs in the terrestrial environment.

  土壤中塑料残留物破碎和降解会导致纳米塑料污染。对于酞酸酯等污染物共存条件下纳米塑料环境行为认识的不足影响了对其环境危害的评估。本研究通过柱实验考察了聚苯乙烯纳米塑料（PSNPs）、羧基聚苯乙烯纳米塑料（PSNPs−COOH）和氨基聚苯乙烯纳米塑料（PSNPs−NH₂）在针铁矿（GT）和典型酞酸酯DEHP包被砂质饱和含水介质中迁移行为，并利用量子化学计算揭示了其迁移机理。结果表明，GT可不同程度降低三种纳米塑料的迁移能力，DEHP的存在进一步阻滞纳米塑料的迁移。PSNPs与GT之间存在范德华力和静电相互作用，导致了PSNPs在迁移过程中的沉积。PSNPs−COOH与GT间的配体交换作用使其沉积量大于PSNPs。虽然DEHP与纳米塑料间可形成氢键，但砂表面正电荷和化学异质性的增加是DEHP促进纳米塑料沉积的主要原因。由于PSNPs−NH₂的负zeta电位绝对值较低，因此对化学异质性相对敏感，在GT和GT-DEHP包被的砂柱中完全沉积（沉积率超过96.9%）。相比配位键、范德华力、静电作用和氢键作用，含水介质表面的化学异质性可能更容易导致纳米塑料迁移过程中的沉积。本研究揭示了GT和GT-DEHP对不同官能团纳米塑料迁移行为的影响，对评估纳米塑料在土壤生态环境中的危害起到支撑作用。