PDF(Pubmed)
Abstract：
The photodegradation of macroplastics in the marine environment remains poorly understood. Here, we investigated the weathering of commercially available plastics (tabs 1.3 × 4.4 × 0.16 cm), including high-density polyethylene, low-density polyethylene, polypropylene, polystyrene, and polycarbonate, in seawater under laboratory-simulated ultraviolet A radiation for 3-9 months, equivalent to 25-75 years of natural sunlight exposure without considering other confounding factors. After the exposure, the physical integrity and thermal stability of the tabs remained relatively intact, suggesting that the bulk polymer chains were not severely altered despite strong irradiation, likely due to their low specific surface area. In contrast, the surface layer (∼1 μm) of the tabs was highly oxidized and eroded after 9 months of accelerated weathering. Several antioxidant additives were identified in the plastics through low temperature pyrolysis coupled with gas chromatography/mass spectrometry (Pyr-GC/MS) analysis. The Pyr-GC/MS results also revealed many new oxygen-containing compounds formed during photodegradation, and these compounds indicated the dominance of chain scission reactions during weathering. These findings highlight the strong resistance of industrial macroplastics to weathering, emphasizing the need for a broader range of plastics with varying properties and sizes to accurately estimate plastic degradation in the marine environment.
摘要：
对海洋环境中大型塑料的光降解仍知之甚少。这里,我们调查了市售塑料的风化(标签1.3×4.4×0.16厘米)，包括高密度聚乙烯,低密度聚乙烯，聚丙烯,聚苯乙烯,和聚碳酸酯，在实验室模拟紫外线A辐射下的海水中3-9个月，相当于25-75年的自然阳光照射，而不考虑其他混杂因素。曝光后,标签的物理完整性和热稳定性保持相对完整，这表明，尽管有强烈的辐射，本体聚合物链并没有严重改变，可能是由于它们的比表面积低。相比之下,经过9个月的加速风化后，接头的表面层（〜1μm）被高度氧化和侵蚀。通过低温热解和气相色谱/质谱（Pyr-GC/MS）分析，确定了塑料中的几种抗氧化添加剂。Pyr-GC/MS结果还揭示了光降解过程中形成的许多新的含氧化合物，这些化合物表明了风化过程中断链反应的优势。这些发现突出了工业大型塑料对风化的强大抵抗力，强调需要更广泛的具有不同性质和尺寸的塑料，以准确估计海洋环境中的塑料降解。
