Oil and POPs Research Group, Korea Institute of Ocean Science and Technology , Geoje 53201, Republic of Korea.
Department of Marine Environmental Sciences, Korea University of Science and Technology , Daejeon 34113, Republic of Korea.
Environ Sci Technol. 2017 Apr 18;51(8):4368-4376. doi: 10.1021/acs.est.6b06155. Epub 2017 Mar 28.
It is important to understand the fragmentation processes and mechanisms of plastic litter to predict microplastic production in the marine environment. In this study, accelerated weathering experiments were performed in the laboratory, with ultraviolet (UV) exposure for up to 12 months followed by mechanical abrasion (MA) with sand for 2 months. Fragmentation of low-density polyethylene (PE), polypropylene (PP), and expanded polystyrene (EPS) was evaluated under conditions that simulated a beach environment. PE and PP were minimally fragmented by MA without photooxidation by UV (8.7 ± 2.5 and 10.7 ± 0.7 particles/pellet, respectively). The rate of fragmentation by UV exposure duration increased more for PP than PE. A 12-month UV exposure and 2-month MA of PP and PE produced 6084 ± 1061 and 20 ± 8.3 particles/pellet, respectively. EPS pellets were susceptible to MA alone (4220 ± 33 particles/pellet), while the combination of 6 months of UV exposure followed by 2 months of MA produced 12,152 ± 3276 particles/pellet. The number of fragmented polymer particles produced by UV exposure and mechanical abrasion increased with decreasing size in all polymer types. The size-normalized abundance of the fragmented PE, PP, and EPS particles according to particle size after UV exposure and MA was predictable. Up to 76.5% of the initial EPS volume was unaccounted for in the final volume of pellet produced particle fragments, indicating that a large proportion of the particles had fragmented into undetectable submicron particles.
了解塑料垃圾的碎片化过程和机制对于预测海洋环境中的微塑料生成非常重要。本研究在实验室中进行了加速风化实验，使用紫外线（UV）照射长达 12 个月，然后使用沙子进行机械磨损（MA）2 个月。在模拟海滩环境的条件下评估了低密度聚乙烯（PE）、聚丙烯（PP）和膨胀聚苯乙烯（EPS）的碎片化情况。MA 未经过 UV 光氧化时，PE 和 PP 的碎片化程度最小（分别为 8.7 ± 2.5 和 10.7 ± 0.7 个/颗粒）。随着 UV 暴露时间的延长，PP 的碎片化速度比 PE 更快。12 个月的 UV 暴露和 2 个月的 MA 对 PP 和 PE 的处理导致分别产生 6084 ± 1061 和 20 ± 8.3 个/颗粒。EPS 颗粒仅在 MA 作用下就易碎片化（4220 ± 33 个/颗粒），而 6 个月的 UV 暴露后再进行 2 个月的 MA 处理则产生 12152 ± 3276 个/颗粒。在所有聚合物类型中，经 UV 暴露和机械磨损处理后产生的碎片化聚合物颗粒数量随聚合物粒径的减小而增加。根据 UV 暴露和 MA 后粒径的归一化大小，可预测 PE、PP 和 EPS 碎片化颗粒的丰度。在最终产生的颗粒碎片中，高达 76.5%的初始 EPS 体积无法用未被计算在内，这表明很大一部分颗粒已碎片化成为无法检测到的亚微米颗粒。
