Microplastics, especially aged microplastics can become vectors of metals from environment to organisms with potential negative effects on food chain. However, a few studies focused on the bioavailability of adsorbed metals and most studies related to aged microplastics used artificial method that cannot entirely reflect actual aging processes. In this study, virgin polystyrene was aged by ozone (PS-O₃), solar simulator (PS-SS) and lake (PS-lake) to investigate adsorption of Cu by virgin, artificially and naturally aged microplastics and subsequent release in simulated gastrointestinal fluids (SGF). Characterization results show carbonyl was formed in PS-O₃ and PS-SS, and the oxidation degree was PS-O₃ > PS-SS > PS-lake. However, Cu adsorption capacity followed this order PS-lake (158 μg g⁻¹) > PS-SS (117 μg g⁻¹) > PS-O₃ (65 μg g⁻¹) > PS-virgin (0). PS-O₃ showed highest Cu adsorption capacity at 0.5 h (71 μg g⁻¹), but it dropped dramatically later (10 μg g⁻¹, 120 h), because PS-O₃ could break up and the adsorbed Cu released in solutions subsequently. For PS-lake, precipitation of metallic oxides contributes to the accumulation of Cu. The addition of dissolved organic matter (DOM) could occupy adsorption sites on PS and compete with Cu, but also can attach PS and adsorb Cu due to its rich functional groups. The simultaneous ingestion of microplastics with food suggested that adsorbed Cu is solubilized mostly from aged PS to SGF.

中文翻译：

---

自然和人工老化的聚苯乙烯微塑料对铜的吸附以及随后在模拟胃肠液中的释放

微塑料，特别是老化的微塑料可以成为金属从环境到生物体的载体，对食物链产生潜在的负面影响。然而，少数研究侧重于吸附金属的生物利用度，大多数与老化微塑料相关的研究采用人工方法，不能完全反映实际的老化过程。在本研究中，原始聚苯乙烯通过臭氧 (PS-O ₃ )、太阳模拟器 (PS-SS) 和湖 (PS-lake) 进行老化，以研究原始、人工和自然老化微塑料对铜的吸附以及随后在模拟胃肠道中的释放液体（SGF）。_{表征结果表明，PS-O 3}和PS-SS均形成羰基，氧化程度为PS-O ₃ > PS-SS > PS-lake。然而，Cu吸附容量遵循以下顺序：PS-lake (158 μg g ^-1 ) > PS-SS (117 μg g ^-1 ) > PS-O ₃ (65 μg g ^-1 ) > PS-virgin (0)。PS-O ₃在 0.5 h 时表现出最高的 Cu 吸附容量（71 μg g ^-1），但随后急剧下降（10 μg g ^-1， 120 h），因为 PS-O ₃会分解，吸附的 Cu 释放出来。随后的解决方案。对于PS-lake，金属氧化物的沉淀有助于Cu的积累。添加溶解有机物(DOM)不仅可以占据PS上的吸附位点并与Cu竞争，而且由于其丰富的官能团也可以附着PS并吸附Cu。微塑料与食物的同时摄入表明，吸附的铜主要从老化的 PS 溶解到 SGF 中。