Numerous studies have focused on the interaction between microplastics (MPs) and phenanthrene (PHE) in aquatic environments. However, the intricate roles of aquatic humic substances (HS), which vary with environmental conditions, in influencing PHE-MP interactions are not yet fully understood. This study investigates the variable and environmentally sensitive roles of HS in modifying the interactions between PHE and polyethylene (PE) MPs under laboratory-simulated aquatic conditions with varying solution chemistry, including pH, HS types, HS concentrations, and ionic strength. Our findings show that the presence of HS significantly reduces the adsorption of PHE onto both pristine and aged PE MPs, with a more pronounced reduction observed in aged PEs. This effect is highlighted by a notable decrease in the partitioning coefficient (K) of PHE, which falls from 2.60 × 10 to 1.30 × 10 L/kg on MPs in the presence of HS. The study also demonstrates that alterations in the net charge of HS solutions are crucial in modifying PHE distribution onto PEs. An initial decrease in K values at higher pH levels is reversed when HS is introduced. Furthermore, an increase in HS concentrations is associated with lower K values. In conditions of higher ionic strength, the retention of PHE by HS is intensified, likely due to an enhanced salting-out effect. This research highlights the significant role of aquatic HS in modulating the distribution of PHE in MP-polluted waters, which is highly influenced by various solution chemistry factors. The findings are vital for understanding the fate of PHE in MP-contaminated aquatic environments and can contribute to refining predictive models that consider diverse solution chemistry scenarios.

中文翻译：

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水生腐殖质对微塑料污染的水生系统中菲分布的环境条件依赖性影响

许多研究都集中在水生环境中微塑料 (MP) 和菲 (PHE) 之间的相互作用。然而，水生腐殖质 (HS) 在影响 PHE-MP 相互作用方面的复杂作用尚未完全了解，该作用随环境条件而变化。本研究调查了在实验室模拟的水生条件下，在不同溶液化学（包括 pH、HS 类型、HS 浓度和离子强度）下，H2S 在改变 PHE 和聚乙烯 (PE) MP 之间相互作用方面的可变和环境敏感作用。我们的研究结果表明，H2S 的存在显着降低了原始 PE MP 和老化 PE MP 上的 PHE 吸附，其中在老化 PE MP 中观察到更明显的降低。这种效应通过 PHE 的分配系数 (K) 显着降低而得到凸显，在 HS 存在下，PHE 的分配系数 (K) 从 2.60 × 10 L/kg 降至 1.30 × 10 L/kg。该研究还表明，HS 溶液净电荷的变化对于改变 PHE 在 PE 上的分布至关重要。当引入 H2S 时，K 值在较高 pH 水平下的初始下降会逆转。此外，HS 浓度的增加与较低的 K 值相关。在离子强度较高的条件下，HS 对 PHE 的保留会增强，这可能是由于盐析效应增强。这项研究强调了水生 H2S 在调节 MP 污染水中 PHE 分布方面的重要作用，而这种作用受各种溶液化学因素的影响很大。这些发现对于了解 MP 污染的水生环境中 PHE 的命运至关重要，并且有助于完善考虑不同溶液化学场景的预测模型。